Final Report Summary - SULFREE (Tyre Recycling Pyrolysis for producing oil with less than 0.2% sulphur content, low cost sulphur impregnated carbon for reducing mercury air emissions, with simultaneous elemental)
Executive Summary:
PUBLISHABLE SUMMARY
The Sulfree project sets out to convert low-value rubber crumb into high value products, including activated carbon and low-sulphur pyrolysis oils. Sulfree is a novel end of life tyre recycling process that employs microwave pyrolysis technology. Pyrolysis is thermal decomposition of organic materials in the absence of oxygen. Tyres due to their high carbon content are ideal candidates. Pyrolysis of end of life tyres results in a gas, a liquid (oil) and a solid carbon char (carbon black) fraction.
The major novelty of the project is the development of a complete desulphurisation process that reduces the sulphur content of the pyrolysis oils and gas, with sulphur recovery. This enables the sale of the pyrolysis oils as light sweet crude oil, currently sold at $90/bbl and estimated to reach by 2020 $125/bbl.
A working Sulfree rig was produced this was then used for optimising the process. During the process oil is continually condensing from the vapours produced during the pyrolysis process and collected. After five dispenses the excess hot carbon is ejected from the pyrolysis chamber and via a screw conveyor and is cooled and collected ready for dispensing. This screw conveyor and carbon cooling process is computer controlled via a dedicated computer programme.
The key measures of pyrolysis success are production of ‘dry’ carbon (i.e. fully-pyrolysed solid material that does not contain any pyrolysis oil) and recovery of the maximum yield of condensable pyrolysis oil. Both of these outputs are strongly affected by the pyrolysis temperature and the residence time in the pyrolysis chamber, along with the inertness of the atmosphere inside the pyrolysis zone, the mixing regime adopted and how the carbon and oil are cooled outside of the pyrolysis chamber.
The optimum temperature to achieve full pyrolysis of rubber crumb without unnecessary ‘over-heating’ was previously determined using thermogravimetric analysis and found to be 450 °C. This was therefore set as the target temperature for the reactor.
After each trial, the pyrolysis oil was recovered and the total volume determined. It was found that, for our system, the relationship between oil volume produced and degree of pyrolysis was almost linear (e.g. 85% pyrolysis of the crumb generated 85% of the theoretical maximum of pyrolysis oil) Changing operating parameters inside our chamber had very little impact on oil production and, as the most valuable component of our system is the carbon and not the pyrolysis oil, this production rate was not optimised further.
The design of the mixing blades ensures the walls of the chamber are kept clean, as the constant movement of the blades inside the chamber stops material building up on the walls. This is a significant advantage over many typical pyrolysis units. A second significant advantage of the Sulfree system is the lack of formation of waxes, which is a common problem in wholly thermal pyrolysis systems. It appears that microwave pyrolysis of rubber crumb significantly reduces the production of waxes, although the reason for this is unclear.
Energy and mass balance calculations have been carried out and the calculations estimate that the total cost of pyrolysis and oil treatment for 1 kilogram of crumb at steady state would therefore be 1 kilogram of crumb at steady state could be €1.62 (worst case scenario) or €0.17 at 90% efficiency of energy recovery from hydrogen.
During the project the following successes were achieved:
• Successful pyrolysis of rubber crumb using microwave technology
• One step “carbon black” production
• Modular design.
• Overall system designs for all sub-units to allow scale-up and installation at commercial end-user sites
• High efficiency process.
• Instant heating
• Internal reactor conveyance system
• Self cleaning
• Stop/start – semi continuous
• Low odour (clean process), low tar production
• Fine carbon black particle size
• Production of “carbon black” and “low sulphur oil” with significant resale value to make the system commercially viable
• Identification of a suitable HDS catalyst to remove sulphur from pyrolysis oil
• Optimised HDS process for the recovery of sulphur-rich gas and low-sulphur oil
The proof of concept for the Sulfree project has proved that this technology is now ready for progressing to the commercialisation of the process. All the SME partners have agreed an exploitation strategy.
A video of the working plant has is available for viewing on the Sulfree project website www.sulfree.eu
Project Context and Objectives:
SULFREE is a novel end of life tyre recycling process that employs microwave pyrolysis technology. Pyrolysis is thermal decomposition of organic materials in the absence of oxygen. Tyres due to their high carbon content are ideal candidates. Pyrolysis of end of life tyres (ELT) results in a gas (syn-gas), a liquid (oil) and a solid carbon char (carbon black) fraction.
An end of life tyre (ELT) is defined as a tyre that can no longer be used on vehicles and cannot be re-treaded anymore. All tyres (passenger cars, trucks and airplanes, two wheel and off-road vehicles) result in ELT. The bulk of ELTs results from car and truck tyres. ELT are classified as non-hazardous waste (75/442/EEC, Directive 91/156/EC).
Every year approximately 1.5 billion new tyres are sold worldwide and just as many are categorized as end of life. Despite an increase in the service life of tyres, these volumes are constantly rising due to the growing number of vehicles and increasing traffic worldwide. In Europe, in 2011 3.3 million tonnes of used tyres were generated. Of those, 173 tonnes were reused, 122 tonnes were exported, 286 tonnes were re-treaded and 2.7 million tonnes of ELT remained on the EU market for recovery and recycling, a 2.2% increase compared with 2009 and a fivefold increase over the last 17 tears. The annual cost for the management of ELTs is €600 million. There are also in the EU 5.7 million tonnes of old stockpiles (historic stockpiles) of used tyres that have been illegally dumped or stockpiled in landfills.
The main drive for the recycling and recovery of end of life tyres is the current EU legislation, with which all EU member states must comply. Legislation restricts the landfill of tyres and tyre waste and is an important factor that drives the industry to recycle tyres. However, despite the ban on landfilling (whole and shredded tyres), there are still the old tyre stockpiles. The legislative imperative for end of life tyre (ELT) recycling is defined by the following EU directives. The Directive on the Landfill of Waste (1999/31/EC) banned the landfill of certain whole and shredded tyres effective July 2003 (for whole tyres) and July 2006 (for shredded tyres. The End-of-Life Vehicle (ELV) Directive (2000/53/EC) sets a target of 95% recovery/reuse by 2015 for vehicles below 3.5 tonnes and indirectly setting targets for a part of ELT in the EU (10% of total ELT arise from ELV as defined by 2000/53/EC). To achieve these ambitious targets, ELV processors require the tyres to be recycled.
World tyre demand is forecasted to rise 4.7 percent per year through 2015 to 3.3 billion units, despite the current economic uncertainty. Global car tyre sales are expected to increase from 290 million passenger car tyre sales in 2010 to 400 million units by 2020 and replacement car tyre sales from 760 million units in 2010 to 1.2 billion units by 2020. The large motor vehicle tire market will accelerate its growth through 2015, advancing to 1.9 billion units. The Asia/Pacific region is by far the largest market for tires, accounting for over half of global tire consumption8.
This increased demand will result in a directly analogous, significant increase in the number of ELT in the EU and USA but also in new and emerging markets (e.g. China, India). Currently, the global output for ELT is 1.5 billion (2011), and will rise as high as 3 billion in 2015.
ELT derived products are typically of low value and do not take advantage of the fact that tyres consist of valuable resources (rubber – carbon, oil, steel, sulphur) and are also themselves a valuable commodity. The average price for a passenger tyre ranges from €60 to €300 and according to industry experts, the cost to produce a tyre is: 30% raw materials, 30% CAPEX (expenditures creating future benefits overhead, environmental cost), 30% labour and 10% profit.
The SULFREE process is the following. The steel content of the tyre is removed before shredding and the tyres are cleaned if needed (e.g. to remove residual chorine); this is standard procedure for the tyre crumb providers. The steel is removed before shredding and pyrolysis to improve the quality of the steel and to extend the operational lifetime of the tyre shredding machinery. The machinery and the crumb will be provided by one of the SME partners, as this is a mature area where no R&D efforts will be applied. The tyre crumb is fed at a rate of 125 kg/h (1000 tyres/day) to the pyrolysis chamber via a mixer and screw feeding system; this design enables the constant mixing of the tyre crumb. The microwave heating system operates at 600°C to pyrolyse the crumb to gas, oil and carbon char. The pyrolysis products are then separated and the oil and gas are cooled and combined to a vapour and are fed to the fixed bed reactor at a temperature of 250°C. The vapour undergoes hydrodesulphurisation (HDS) in the fixed bed reactor, using specially selected catalysts that will be identified during the R&D activity. Following this, the vapour is condensed and the oil with less than 0.2 % sulphur is recovered. The gas, now rich in hydrogen sulphide (H2S), is cooled down to 44°C and is passed through a monoethalomine (MEA) stripper to hold the H2S. The elemental sulphur is then recovered using the Claus process (recovery rate at least 95%). The gas then can be burned to cover the heat and energy requirements of the process. The carbon char is inputted to the activation chamber at a temperature of 400°C and at a rate of 35kg/h, where it is activated using steam, in a low oxygen environment.
The major novelty of the project is the development of a complete desulphurisation process that reduces the sulphur content of the pyrolysis oils and syn-gas, with sulphur recovery. This enables the sale of the pyrolysis oils as light sweet crude oil, currently sold at $90/bbl and estimated to reach by 2020 $125/bbl.
The aim is to produce from ELT (a) oil with low sulphur content (less than 0.2%) suitable for use as sweet crude oil and in accordance with EU regulations (b) high quality sulphur-impregnated activated carbon (S-AC) that can be used in high value applications (e.g reduce mercury emissions), (c) elemental sulphur and (d) steel recovered from the tyre before pyrolysis.
The pyrolysis sulphur rich carbon black is activated to high quality sulphur-impregnated activated carbon using a one-step procedure, thereby increasing the carbon black’s commercial value: typical prices for S-AC are €7.00 - €12.00/kg.
An additional novelty is the process’s energy management. Pyrolysis, desulphurisation and steam activation are all energy intensive. By integrating them and using waste heat from the system and the sulphur-low syn-gas, the energy requirements can be fulfilled internally by at least 60%. This large energy saving results in significant cost savings.
The SULFREE plant will have an input capacity of 1,000 tyres per day, equivalent to 125 kg/h, with a 90% material recovery. The following table summarizes the outputs versus the average end of life tyre composition, which is the process’s raw material.
To successfully achieve the SULFREE process and produce the desired end products, the following scientific and technological objectives are set.
Scientific
1. Numerical modelling of the pyrolysis process to optimize conditions and yields. Fully characterize pyrolysis oils produced under different operating conditions and produce a parametric model, with attention to the remaining sulphur fractions. Selection of best suited desulphurization method based on the characterization of pyrolysis oils.
2. Understand how process parameters and fixed bed reactor size affect effectiveness. How to successfully construct an FBR at a smaller size while retaining required temperature and pressure to ensure optimal H2S formation.
3. Enhance our understanding of H2S removal from the gas stream using MEA (Monoethanolamine): initial H2S concentration, heat, pressure and steam requirements, effectiveness, MEA regeneration
4. Enhance our understanding of how operating conditions (e.g. concentration, contact time, reaction temperature, number of stages) affect the Claus process for recovering 95% of elemental sulphur, from the resulting acid gases after MEA treatment.
5. Enhance our understanding of how to control microwave processing conditions such as energy input, wave scattering, and pulse duration and how moisture conditions and degree of reaction effect microwave heating.
6. Enhance our understanding of how operating conditions during manufacture affect final S-AC quality; surface area of the activated carbon, mechanical properties, Hg absorption kinetics, Hg absorption capacity and knock on effects on final disposal or reactivation.
7. Enhance our understanding of the total energy requirements of the process and use waste heat and the syn-gas for fulfilling them in-situ, at least by 60 – 70%.
Technological
1. Input capacity of 1000 tyres per day (125 kg/h)
2. Oil with sulphur content less than 0.2% (sweet crude oil type) and a yield rate of 40% per tonne of tyres processed.
3. S-AC with an Hg capacity of 1.5mg/g able to achieve at least a 93% reduction of Hg in ratio’s of 9 mg S-AC/m3 flue gas and a yield rate of 36% per tonne of tyres processed.
4. A yield rate of 12% steel per tonne of tyres processed.
5. A yield rate of 1.4% of elemental sulphur per tonne of tyres processed.
Their successful realisation will result in the development and manufacturing of: (a) the pyrolysis chamber with a combined microwave heating unit and mixer and screw design for inputting the tyre crumb, (b) the one-step carbon black steam activation unit, (c) the fixed bed reactor for HDS of the pyrolysis oil, (d) the MEA stripper for removing the H2S from the gas, with sulphur recovery, (e) the heat exchange and energy recovery unit and (f) the automation system and control software for the SULFREE plant. Their successful integration will result in the complete SULFREE plant, capable of meeting the technological objectives, which is the integration objective.
Project Results:
The Sulfree project sets out to convert low-value rubber crumb into high value products, including activated carbon and low-sulphur pyrolysis oils. Sulfree is a novel end of life tyre recycling process that employs microwave pyrolysis technology. Pyrolysis is thermal decomposition of organic materials in the absence of oxygen. Tyres due to their high carbon content are ideal candidates. Pyrolysis of end of life tyres results in a gas, a liquid (oil) and a solid carbon char (carbon black) fraction.
The major novelty of the project is the development of a complete desulphurisation process that reduces the sulphur content of the pyrolysis oils and gas, with sulphur recovery. This enables the sale of the pyrolysis oils as light sweet crude oil, currently sold at $90/bbl and estimated to reach by 2020 $125/bbl.
Work Package 1 “Development of Pyrolysis Unit”
The first task was to fully specify the microwave chamber design and the microwave heating system in order to achieve a sufficient heating rate to process up to 125 kg/h tyre crumb at up to 600 °C. The size of the chamber was largely governed by the former, while the microwave energy input was controlled by the latter. Due to the high heat of the system and corrosive nature of the vapour, 316 stainless steel was chosen as the construction material. Consideration was given to materials of construction for the microwave windows and the microwave power required achieving the necessary heating. Computational calculations showed that 600 °C could be achieved using 10 kW of microwave power delivered over 25 minutes. Five 2 kW magnetrons were therefore specified. Using these figures and considerations, the processing chamber and microwave heating systems were designed to achieve a minimum processing throughput of 1 kg/min rubber crumb, or 60 kg/h. The final design has been fully reported in “Deliverable 1.1 Complete specification of microwave pyrolysis unit”
Considerable thought was given to the internal mixing and conveying system within the chamber, as calculations showed good mixing would be critical to achieve full pyrolysis of the rubber crumb. A number of designs were considered and rated on their complexity of manufacture, ease of use and control and overall suitability to the system. Once the design was selected, further consideration was given to seals, bearings and motors, all of which were specified to complete the design.
The most cost-effective method of producing an inert atmosphere is to use nitrogen gas. A system was therefore developed to introduce nitrogen gas into the chamber at specific inlet ports to optimise rubber pyrolysis and also protect key components of the system from heat and carbon char; the motor chamber was cooled with a constant flow of nitrogen in order to protect the motor itself; the ceramic windows installed ahead of the magnetrons were flushed with nitrogen to generate a curtain of gas to help to resist the deposition of carbon onto the windows to stop microwave absorption and cracking of the ceramic; the infra-red temperature sensors were also flushed with nitrogen, again to stop the build-up of soot on the sensors and the generation of false readings; the inlet hopper was flushed with nitrogen to stop oxygen ingress into the system. The constant positive pressure of nitrogen within the system ensures oxygen ingress into the pyrolysis zone cannot occur. This design also removed the requirement for an airlock system, making the unit simpler to construct, operate and maintain.
Having completed the design specification for the chamber, the unit construction began.
Work Package 2 “Identification of optimal pyrolysis processing conditions”
In order to limit the number of optimisation experiments required for the pyrolysis system, detailed lab-scale pyrolysis experiments using rubber crumb in thermogravimetric analysis were undertaken to determine the optimum pyrolysis temperature. These experiments showed that complete pyrolysis of the rubber could be achieved at 450 °C, meaning that the prototype rig could operate at a lower temperature than the 600 °C originally planned. This had a number of benefits, including a lower energy requirement for the system and, in theory, faster processing times and thus throughput rates. By setting 450 °C as the processing temperature, the number of optimisation variables was also reduced, making the Design of Experiments (DoE) process easier. The main variables were therefore identified as:
• Rubber crumb size
• Temperature ramp rate
• Temperature hold time
Having set up the DoE plan the next challenge was to operate the pyrolysis system.
Work Package 3 “Development of vapour processing unit and activation chamber”
The original plan for the vapour processing unit was a vapour compressor that could take the hot gas directly from the pyrolysis chamber and compress it for injection into the hydrodesulphurisation (HDS) unit. Much research was carried out to find a suitable, commercially-available system, but it became apparent that the original plan would not be viable within the Sulfree project. To begin with, most commercial compressors could not operate at the outlet gas temperature specified and, of those that could; they would be operating at their temperature limit. Also, in order to achieve the pressure required for the HDS unit, a two-stage compressor was required.
The carbon activation chamber and steam injection systems were fitted directly to the bottom outlet of the pyrolysis chamber.
Work Package 4 “Development of fixed-bed reactor”
Catalytic hydrotreating (HDT) is a technique used extensively in the petroleum industry to remove impurities, such as sulfur, nitrogen, oxygen, polynuclear aromatics, and metal-containing compounds (mainly vanadium and nickel). Depending on the nature of the feedstock and the amount and type of the different impurities, specific hydro-treating processes have been developed. The reactions occurring during hydrotreating are hydrodesulfurisation (HDS), hydrodenitrogenation (HDN), hydrodeoxygenation (HDO), hydrodearomatisation (HDA), hydrodemetallisation (HDM), and hydrodeasphaltenisation (HDAs). Concurrently, the average molecular weight of the oil is lowered as a consequence of hydrocracking (HDC) reactions, which can happen without a substantial loss in liquid product yield, as in the HDT of light distillates, or with moderate or severe reduction of molecular weight, such as in the case of heavy feeds.
The severity of reaction conditions depends on the type of feed and on the product quality desired. In general, the higher the boiling point of the feed, the higher the reaction severity.
Hydrotreating processes are mainly conducted on the oil fractions (i.e. after the separation of crude oil to its derivatives such as gasoline, kerosene, heavy and light gas oil and other oil fraction), and not on the full crude oil. This means that a large part of the contaminants, such as sulfur, nitrogen, metals, aromatics and asphaltenes will be deposited at the bottom of the atmospheric and vacuum distillation column. Hydrotreating of each section separately is fairly easy. However, the crude oil hydrotreating process is regarded as a large and difficult challenge since crude oil contains many compounds and complex structures, in addition to multiple phases. In addition, crude oil hydrotreating in the presence of the asphaltenes containing a large component of sulfur and metals (which poison the active sites of the catalyst) is one of the more difficult and important problems.
The main sulfur components of liquid fuels are thiols, sulfides, thiophene and alkylthiophenes, tetrahydrothiophene, thiophenols and benzothiophene. Alkylthiophenes include three and four carbon atom-substituted thiophenes (C3- and C4-thiophenes), thiophene sulfur represents a large fraction of the total sulfur content in light fuels (60 wt% and over). The sulfur compounds in the naphtha fraction, obtained from waste tyre pyrolysis, have previously been reported to be composed of methyl-, dimethyl- and ethylthiophene, trimethyl- and isopropylthiophene, and tert-butylthiophene including benzothiazole. The rates of desulfurisation of thiophene, tetrahydrothiophene and n-butanethiol over various catalysts including alumina-supported cobalt–molybdenum have been investigated in the literature, disclosing that the reactivities of thiophene and tetrahydrothiophene were similar while that of n-butanethiol was much higher (15–40 times). The identification and quantification of these sulfur compounds are not via conventional analysis and they are even more difficult to study when the chemical matrix is very complex and largely unknown, as for pyrolysis oils.
The HDT process is generally carried out in fixed beds (FBRs), moving beds (MBRs), expanded or ebullated beds (EBRs), and slurry bed (SBRs) reactors. The principle of operation of these three groups of reactors is very similar, but they differ in some technical details. Figure 1 below shows schematic representations of the reactors used for catalytic hydrotreating.
Figure 1: Schematic of hydrotreating processes
FBR reactors are utilised mainly for hydrotreating of light feeds, such as naphtha and middle distillates, but they are also used for hydrotreating of heavier feeds, such as petroleum residues. However, when the feed contains large amounts of metals and other impurities (e.g. asphaltenes), the use of FBRs has to be examined carefully, according to the catalyst cycle life. Alternatively, MBR and EBR reactors have demonstrated reliable operation with difficult feeds, such as vacuum residues. When hydrotreating petroleum feeds, the life of the catalyst is crucial to retaining its activity and selectivity. Depending on the feed, the catalyst life may vary on the order of months or years. It is then clear that the timescale of deactivation influences the choice of reactor.
Sulfur compounds present in naphtha are generally easy to remove. That is the reason that only an HDS catalyst is required for sulfur removal in naphtha. However, when processing straight-run gas oil (SRGO), the refractory sulfur compounds are more difficult to remove, making deep HDS for ultra-low sulfur diesel (ULSD) production difficult to achieve. In addition, most of the time, SRGO is blended with light cycle oil (LCO) from catalytic cracking units (FCC), and both are fed to the hydrotreater. Apart from sulfur, LCO also contains high amounts of nitrogen and aromatics, which make the hydrotreating even more difficult, since they either compete for catalytic active sites or consume large amounts of hydrogen. To address this problem, multi-bed systems with different catalysts have been proposed. Also, hydrogen is introduced between the beds as a quench because the reaction is exothermic. The heat released in light feed HDT is relatively low, so that quenching is not necessary and HDT units are designed with just one reactor containing a single catalyst bed. However, for heavier feeds, multiple catalyst beds with cooling in between are used. Multi-bed configurations with a hydrogen quench system are usually employed for hydrotreating of FCC feeds (a blend of heavy atmospheric gas oil and light and heavy vacuum gas oils) and heavier feedstocks.
The bench-scale reactor used in the Sulfree project is an automatic, computerised high-pressure catalytic reactor which includes the valves and process layout inside a hot box to avoid possible condensation of volatile products, while also preheating the reactants efficiently. This equipment has been designed as a universal basic unit that can be modified.
The basic unit includes the reactor (up to 1000 ºC) and valves inside the hot box, 3 mass flow controllers (MFCs), a micro-regulation pressure control system (up to 100 bar +/-0.1 standard), a high-pressure liquid/gas separator with the lowest dead volume available and all common elements designed to work in continuous mode. A six-way valve makes it possible to bypass the reactor before reaction starts, while stabilisation and feed analysis are taking place.
The main characteristics of the equipment are:
• Maximum working pressure 100 bar.
• All layout inside hot box made of SS304 with hot air convector. Maximum recommended temperature 200ºC ± 1ºC. Stable full system temperature avoids cool or hot points on overall layout system.
• Reactor furnace in SS304, with radiant ceramic fibre heaters. Maximum temperature 1100ºC ± 2ºC. Very low thermal inertia (no overshoot) and good temperature distribution.
• Standard Autoclave Engineers tubular micro-reactor in SS316, I.D. = 9.1 mm, L = 300 mm, max. recommended SS316 temperature 650 ºC @ 100 bar or 800 ºC @ 1 bar. Porous plate: 20-40 microns. An analogue reactor in Hastelloys allows increasing the max. working temperature up to 800 °C @ 100 bar or 1200 °C at lower pressure.
• Thermocouple Φ= 1.5 mm, Incoloy, directly inside catalyst bed, without thermowell, for fast response (0.2 sec).
• VICI-Valco 6-port/2-position valves, 280 ºC@100 bar VALCO special HT+HP design, to bypass reactor.
• 3 Modbus mass flow controllers, Hi-Tec Bronkhorst, precision 1% FS, repeatability 0.1%, with process compatible elastomers. DIGITAL Modbus communications. Mass flow controllers are for pure hydrogen (used in HDS process), one for H2S/H2 mixture (used in pre-sulfiding of the catalyst) and one for nitrogen (for purging).
• Shut-off valves and check-valves (Kalrez elastomer) for each MFC, and turbulent flow gas mixer.
• Condenser/separator for liquids based on thermoelectric effect (0 to 60 ºC controlled temperature) without external chiller. Patented all-in-one system with very low dead volume.
• Liquid level micro-sensor on the L/G HP separator, based on the capacitive effect of dielectric liquids, from hydrocarbon range (ε=1.1) to water range (ε=80). Dead volume less than 1 cm3
• Filters at reactor inlet and outlet (low dead volume and high surface capacity) to prevent particles in the system.
• 1/8” SS316 1.5 m heated transfer line to GC, 150 ºC-300 ºC temperature-controlled.
• micro-GC for on-line gas phase analysis.
• Power management for temperature control using advanced phase angle proportional control devices that allow faster and more stable temperature control without overshooting.
• The equipment has several independent safety levels: automatic switch-off in the event of any trouble with liquid level, pressure or temperature, providing a security system separate from the PC. User can specify and define the functions for alarm actions and interlocks, configuring and programming them by touch screen or computer.
A commercial hydrodesulphurisation unit was used that could 0.6kg of vapour per hour, generating oil with less than 0.2% sulphur. This unit was initially trialled with a sample of pyrolysis oil that was obtained from a local supplier and found to be suitable for further trials. The throughput is a maximum of 1kg per hour (well above the required 0.6kg of vapour per hour) and the first trial with non-specific pyrolysis oil generated desulphurised oil with less than 0.2% sulfur with only minor optimisation.
WP5: Development of unit for hydrogen sulphide removal and elemental sulphur recovery
The Sulfree system constitutes a highly innovative system which redefines the tyre recycling process. Through a sophisticated chemical process, the designed plant is able to pyrolyse the crumb rubber retrieving high-quality oil as well as steam activated carbon while re-using a significant amount of energy produced thereby achieving high energy efficiency. Figure 2 illustrates the high-level architecture of the system highlighting the hydrogen sulphide removal and Claus units.
Figure 2: High-level overview of the Sulfree process
The hydrogen sulphide removal (amine) and Claus units are responsible for recovering the sulphur contained in the tyre crumb and yielding it as a product in its elemental form.The off-gases of the hydrotreater of the Sulfree plant will be processed in the amine unit for removal of H2S. The sweetened gas product of the amine unit may be recycled via a compressor to the hydrotreater, in order to save expensive hydrogen, or burnt to generate heat. The sour gas effluent of the amine unit (mainly H2S), is fed to the Claus unit, where it is converted to elemental sulfur.
Theoretical mass balance calculations were carried out in order to understand energy flows for each of the streams into the amine and Claus units. The figures for the amine stripper stage were determined by experiment in the HDS stage and reported previously. Using these figures, it is possible to calculate the mass balances for material flows into the Claus unit.
The mass balance data proved that the bulk of the gas that enters the amine unit post-HDS is hydrogen that has not been used in the reduction process. The amine unit strips out the hydrogen sulphide, allowing the remaining gas to be returned to the HDS process for recycling. A percentage of this hydrogen is extracted by the amine however, which enters the Claus unit and is burned during the recovery of sulphur.
Using data from the HDS stage of the Sulfree process, mass flows have been determined for a range of species into the amine stripper unit and calculated for inputs into the Claus unit. These mass flows have been converted into energy flows for the amine and Claus units, showing a considerable positive energy balance for these two systems when they are combined. This energy could be recovered and used in the rest of the Sulfree system to achieve steam activation of the carbon black and pre-heating of input streams to the HDS and pyrolysis chamber.
WP6: Assessment of energy use and recovery
A significant amount of study was already given to energy flows in the amine and Claus units as, whilst amine extraction of hydrogen sulphide (H2S) requires energy to regenerate the amine, huge quantities of heat are generated in the combustion of H2S to generate elemental sulphur along with the production of super-heated steam. These calculations suggest that the majority of the energy demands of both the steam activation of carbon black and the regeneration of the absorbing amine in the stripper unit could be covered by the combustion of extracted H2S. These basic calculations have allowed us therefore to focus on the energy demands of pyrolysis and hydrodesulphurisation (HDS) to suggest how energy efficient the whole Sulfree process could be.
Calculations show that the energy produced by the Claus units, combined with recoverable energy from cooling units around the system should be sufficient to cover the energy demands of the amine and steam activation units in the Sulfree system. This therefore leaves the pyrolysis unit and the HDS unit consuming energy. Working on the basis that these units have reached steady-state operation at optimum conditions, calculations have been carried out to show that the total heat energy demands for the two processes are between 15.52 and 1.65 kWh, depending on whether heat energy is recovered from process hydrogen. The majority of this energy is required to heat the hydrogen for HDS, with only a small component coming from the energy demands of pyrolysis. Also, the calculations do not consider the need to pressurise the pyrolysis oil, which will increase the overall energy cost associated with HDS. With such a large variation in energy demands, the calculations show it would be critical to recover heat from the spent hydrogen in order for HDS to be commercially viable as part of the Sulfree system.
The heat demanded in the various pieces of equipment will be delivered in the form of 3.5 bars saturated steam, (saturation temperature = 148oC).
➢ The steam will be generated in the heat exchangers of the Claus units, by cooling the thermal stage off-gas.
➢ The balance steam will be created by a dedicated boiler, which will be fed by the sweetened gas of the amine unit and natural gas.
• The steam will be utilized in:
o The reboiler of the amine regenerator,
o The interheater exchangers of the Claus unit’s catalytic stages and
o The carbon activation subunit.
The sweetened gas from the amine unit flows to the fuel gas drum, together with the incondensable gaseous products of the pyrolysis reactor.
The pressure of the drum is kept steady by a split range pressure controller that regulates both the valve of the make-up natural gas and that of the vent to safe location valve. In case of excessive pressure rise, the pressure vessel will be protected by the dedicated pressure relief valve.
The fuel gas product of the drum flows under flow control to the Claus unit thermal stage and to the boiler of the plant. A separate gas flow controller has been provided to support future users. Especially for the boiler, the set point of the fuel gas flow controller is reset by the pressure controller output of the unit’s steam drum.
The steam produced by the Claus unit’s process gas coolers enters the steam drum. The pressure of the steam drum is kept constant by its split range pressure controller. The controller may lower excessive steam pressure, by venting steam to safe location, or increase pressure, by cascading a higher fuel gas flow set point to the firing controller of the boiler.
The drum’s steam is consumed in the reboiler of the amine regenerator and the interheaters of the two catalytic Claus stages, under temperature control.
Steam is also provided under flow control to the carbon activation subunit of the pyrolysis reactor.
In case the pressure of the steam drum increases excessively, the dedicated pressure relief valve will vent steam to safe location, protecting the pressure vessel.
The objective of the previously described control system is the minimization of the energy cost of the pyrolysis, amine and Claus units. This scope is achieved by utilizing preferentially the steam produced as a by-product of the Claus unit and using the boiler only to close the steam mass balance.
At the same time, the fuel gas produced in the plant is used preferentially in the boiler to produce steam and imported natural gas is used only to close the heat balance.
Thus, heat is transferred from the equipment with a surplus, in the form of saturated steam, to the equipment with a deficit. In the same time, natural gas import is minimized in favour of the self-produced fuel gas.
The control system described is based on classical PID control and traditional advanced control, (split range and cascade control). Thus it can be seamlessly integrated in the basic control software implemented for the whole Sulfree project plant, in the same PLC.
From the energy and mass balance calculations that have been carried out and the calculations estimate that the total cost of pyrolysis and oil treatment for 1 kilogram of crumb at steady state would therefore be 1 kilogram of crumb at steady state could be €1.62 (worst case scenario) or €0.17 at 90% efficiency of energy recovery from hydrogen.
WP7: Development of process and supervisory control system
The Sulfree project sets out to convert low-value rubber crumb into high value products, including activated carbon and low-sulphur pyrolysis oils. However, in order to convert the output vapours and carbon from the pyrolysis process into valuable products, the carbon must be steam-activated, and the pyrolysis oils must undergo hydrodesulphurisation to produce a low-sulphur oil.
Hence, the whole process is constituted of six units mostly in series and specifically:
1. Pyrolysis unit
2. Steam activation unit
3. Hydrodesulphurization unit
4. Hydrogen Sulphide removal
5. Elemental sulphur recovery
Gas and liquid treatment, constituted by units 3, 4 and 5 is a critical point. The plant schemes for the whole process including all the plant units were defined in the form of P&IDs.
The Sulfree system completely redefines the tyre recycling process. Through a sophisticated chemical process, the designed plant is able to pyrolyse the crumb rubber retrieving high quality oil as well as steam activated carbon while re-using a significant amount of energy produced thereby achieving high energy efficiency. Figure 2 illustrates the high-level architecture of the system highlighting the pyrolysis unit whose control forms the bases of the optimal controller described in this deliverable report. The H2S removal and Claus units are also highlighted as their control is also part of the optimal controller due to the great impact of their operation on the system’s overall productivity and running cost.
The Hydrogen-sulphide removal and Claus units are responsible for recovering the sulphur contained in the tyre crumb and yielding it as a product in its elemental form. The off-gases of the hydrotreater of the Sulfree plant will be processed in the amine unit for removal of H2S. The sweetened gas product of the amine unit may be recycled via a compressor to the hydrotreater, in order to save expensive hydrogen, or burnt to generate heat. The sour gas effluent of the amine unit (mainly H2S), will be fed to the Claus unit, where it will be converted to elemental sulfur.
Each of the Sulfree units is controlled by a local controller which is based on traditional PID control techniques. The local controllers are responsible for keeping the individual units operating around specific desired values. On top of the local controllers, an energy efficiency controller is used to jointly optimise the operation of the amine and Claus unit operation in order to locally achieve maximum energy efficiency for the Sulfur Recovery subsystem.
Finally, the optimal operation of the entire plant is ensured by the optimal controller lying on the top layer of the Sulfree control architecture. The overall Sulfree plant consists of multiple different components. Each of these components is controlled by a local controller which is based on traditional PID control techniques. The local controllers are responsible for keeping the individual units operating around specific desired values.
However, the optimal operation of the entire plant requires that all the individual process parameters are jointly optimised. This means that the optimal controller encompasses both the sulfur recovery process as well as the pyrolysis system. The latter lies at the core of the Sulfree plant and its operation parameters are critical as they greatly impact the yield of the plant with respect to the various products (sulphur, carbon and oil) as well as the energy consumption.
As a consequence, in order to ensure optimal operation, a two-layer control architecture is employed. The bottom layer is responsible for maintaining the operation parameters of each unit at the desired values while the top layer adjusts these values in order to achieve maximum efficiency with respect to a specific objective function.
The energy efficiency controller described above emerges as an intermediate control layer; it jointly optimises the operation of the amine and Claus unit operation in order to locally achieve maximum energy efficiency. It is therefore integrated in the overall control architecture as a layer in between the local controllers and the global optimal controller as illustrated in Figure 3. Note that only the pyrolysis, H2S removal and Claus units are considered as they have the highest impact in the Sulfree plant’s operation.
Figure 3: Overall Sulfree Control Architecture
WP8: Prototype operation and optimisation
The individual units were integrated together to provide the working Sulfree rig (Figure 4).
Figure 4: The working Sulfree rig
The pyrolysis process has been run at the facilities of HERI. During the process oil is continually condensing from the vapours produced during the pyrolysis process and is collected (Figures 5 and 6) and sent for testing.
Figure 5: Oil condensed and flowing Figure 6: Oil being collected in collection bottle
After five dispenses the excess hot carbon is ejected from the pyrolysis chamber and via a screw conveyor and is cooled and collected ready for dispensing. This screw conveyor and carbon cooling process is computer controlled via a dedicated computer programme (Figure 7).
Figure 7: Computer control process for screw conveyor and carbon cooling process.
Carbon has also been collected and sent for testing to determine its BET value.
A video of the working plant has is available for viewing on the Sulfree project website www.sulfree.eu
The key measures of pyrolysis success are production of ‘dry’ carbon (i.e. fully-pyrolysed solid material that does not contain any pyrolysis oil) and recovery of the maximum yield of condensable pyrolysis oil. Both of these outputs are strongly affected by the pyrolysis temperature and the residence time in the pyrolysis chamber, along with the inertness of the atmosphere inside the pyrolysis zone, the mixing regime adopted and how the carbon and oil are cooled outside of the pyrolysis chamber.
The optimum temperature to achieve full pyrolysis of rubber crumb without unnecessary ‘over-heating’ was previously determined using thermogravimetric analysis (TGA, Figure 5) and found to be 450 °C. This was therefore set as the target temperature for the reactor.
Building on from the results earlier in the project, the temperature of 450 °C was therefore aimed for using microwave power. It is important to achieve this temperature as quickly as possible inside the pyrolysis zone, in order to achieve full pyrolysis of the rubber and minimise the production of non-condensable gas. The microwave power input was therefore adjusted over a range from 50% to 90% of full power and the resulting temperature profiles recorded. These first trials demonstrated that, at 50% of full power, the temperature of 5kg of crumb inside the chamber could not be raised to 450 °C within the target residence time of 25 minutes. Raising the input power to 75% of maximum allowed us to achieve the target temperature, but this took over 20 minutes and the recovered rubber after treatment was not fully pyrolysed. Raising the power again to 90% of maximum allowed us to heat the rubber crumb to 450 °C within 20 minutes, therefore providing a hold time of 5 minutes in the final heated zone. The recovered material after treatment at this temperature was 75% pyrolysed on average.
Figure 5: TGA trace for pyrolysis of rubber crumb at various temperatures
To improve this degree of pyrolysis without increasing the hold time or energy input, the mixing regime was investigated. The first trials had minimal mixing, with only one mix after 3 minutes heating and a mix while the material was being moved between heated zones. A range of mixing trials were carried out and the recovered carbon material analysed for completeness of pyrolysis. It was found that, although mixing had only a small effect on pyrolysis efficiency, 85% pyrolysis could be achieved if the material was mixed every minute, along with being mixed during transfer between microwave zones. This is not particularly surprising, as mixing ensures that material that is not exposed to microwave energy (as it is within the bulk material or outside of the microwave treatment window) is moved and exposed to the energy.
It was suggested that increasing the power output of the magnetrons still further to 95% of total power would drive the pyrolysis to completion. However, trials at this power output led to significant problems with the rig, as the magnetrons consistently overheated and cut out. Damage was also caused to the power boards of the magnetrons.
After each trial, the pyrolysis oil was recovered and the total volume determined. It was found that, for our system, the relationship between oil volume produced and degree of pyrolysis was almost linear (e.g. 85% pyrolysis of the crumb generated 85% of the theoretical maximum of pyrolysis oil) Changing operating parameters inside our chamber had very little impact on oil production and, as the most valuable component of our system is the carbon and not the pyrolysis oil, this production rate was not optimised further.
Although we could not achieve complete pyrolysis of 5kg of feed crumb within 25 minutes as we originally hoped (1kg/min throughput), slowing the process down to 40 minutes (0.625kg/min) allowed us to achieve over 95% pyrolysis of the input carbon. This is a suitable level to use in the carbon activation stage, as the heat used in the activation process will complete the pyrolysis without major detriment.
Analysis of the recovered carbon showed it to have a BET adsorption volume of 60 m3/g as recovered after pyrolysis. The entry grade for activated carbon is around 400 m3/g. To obtain carbon with a relatively high adsorption capacity after pyrolysis was also unexpected and suggests that further activation should lead to high-quality activated carbon.
Once the operating parameters to achieve optimum pyrolysis had been determined, consideration was given to the optimum operation of the rig itself. This included parameters such as inert gas flow rate into each section of the rig, flow of cooling water and consideration of cleaning regimes.
The flow rate of inert gas to purge the system and protect the microwave windows and thermal sensors from soot was supplied from the same feed. The percentage of flow to each section of the rig was therefore investigated to minimise total gas input whilst ensuring the temperature sensors and microwave windows were kept soot-free (thus reducing total operating costs.) It was determined by experiment that a flow rate of 5 litres/minute total flow across the microwave windows (i.e. 1l/min across each individual window) and a total flow of 3 litres per minute across the thermal sensors protected these components from soot; even after numerous runs in the chamber the sensors and windows showed only minimal soot contamination at these flow rates. A total gas flow of 20l/min into the chamber was therefore used to purge the system and keep it inert. It may be possible to reduce this value still further, but this flow rate is already low and unlikely to have a significant impact on operating costs.
Cooling water was supplied from a chiller unit, which controlled the temperature at 8 °C and a flow rate of 60l/min. This water was used to keep the condenser/coalescer system cool and ensure recovery of pyrolysis oil. Analysis of the non-condensable gas from the system showed that no further pyrolysis oil could be condensed, indicating that the chiller was operating efficiently. As the chiller water was taken from a bulk feed, this temperature and flow rate was not adjusted.
Finally, considering cleaning requirements, the rig was opened up to inspect the internal surfaces, stirring blades and valves. Surprisingly, even after prolonged use, the inside of the chamber and paddles remained free of soot or waxes and, as described above, the windows and sensors remained relatively soot-free.
We believe it is the design of the mixing blades that ensures the walls of the chamber are kept clean, as the constant movement of the blades inside the chamber stops material building up on the walls. This is a significant advantage over many typical pyrolysis units. A second significant advantage of the Sulfree system is that lack of formation of waxes, which is a common problem in wholly thermal pyrolysis systems. It appears that microwave pyrolysis of rubber crumb significantly reduces the production of waxes, although the reason for this is unclear.
After numerous teething troubles with the pyrolysis unit, complete pyrolysis of rubber crumb has been achieved but at a slightly lower throughput rate than originally planned. This is mainly down to issues with the magnetrons used in the process. We are confident that, with modification of these units, the throughput of rubber crumb in the Sulfree process could be increased. Recovered carbon is free from pyrolysis oil and has a BET gas adsorption capacity of 60 m3/g without further steam/chemical activation.
For the pyrolysis oil, the goal to produce an oil with less than 0.2% of sulphur has been achieved and exceeded in all the tests. The produced pyrolysis oil has properties typical of a light fuel oil for heating or industrial applications. Our HDS unit can process 0.6kg of vapour per hour as originally specified.
After extensively testing at the RTD performer’s site (HERI), the Sulfree rig (Figure 4) should have been shipped to Crumb’s facilities at Dromiskin, Co. Louth and installed where it would undergo extensive trials in a real-world setting by all partners and will be fully optimised to consistently obtain low-sulphur pyrolysis oil (sulphur < 0.2% by mass) and activated carbon that meets the specifications (Hg capacity of 1.5mg/g 93% reduction of Hg in ratios of 9 mg S-AC/m3 flue gas).
However, the facility at Dromiskin, Co. Louth is being decommissioned hence it was not possible to install any new plant or equipment on this site, whereas the new facility at Drogheda, Co. Louth is being commissioned and although plant and equipment can be moved and installed from the original facility no new plant or equipment can be installed until the facility has been inspected and an operating licence has been issued by the council and Health and Safety officials.
The consortium partners therefore agreed to keep the Sulfree rig at the RTD performer’s site (HERI) where further optimisation took place and there was also the opportunity for any partners to visit to carry out further trials if they wished. The consortium believe that this has had no detrimental effect on the project.
The proof of concept for the Sulfree project has proved that this technology is now ready for progressing to the commercialisation of the process and during the project the following successes were achieved:
• Successful pyrolysis of rubber crumb using microwave technology
• One step “carbon black” production
• Modular design.
• Overall system designs for all sub-units to allow scale-up and installation at commercial end-user sites
• High efficiency process.
• Instant heating
• Internal reactor conveyance system
• Self-cleaning
• Stop/start – semi continuous
• Low odour (clean process), low tar production
• Fine carbon black particle size
• Production of “carbon black” and “low sulphur oil” with significant resale value to make the system commercially viable
• Identification of a suitable HDS catalyst to remove sulphur from pyrolysis oil
• Optimised HDS process for the recovery of sulphur-rich gas and low-sulphur oil
Potential Impact:
There are 4200 EU companies active in tyre and rubber activities, with an employment of 360,000 and total turnover €43bn per year. The recycling and waste treatment sector in the EU has a turnover of €227 billion, corresponding to 2.2% of EU GDP, including waste treatment (€52 billion) and recycling (€24 billion, over 500,000 jobs). The recycling sector includes over 60,000 companies, of which 97% are SMEs and the EU has one third of the world share of eco-industries and a 50% share of the world market in waste and recycling industries. The EU has a range of regulatory measures dealing with waste, a strategic approach to waste and resources, legislation regulating waste treatment and management of specific waste streams (end-of-life tyres, end-of-life vehicles, biowaste, electrical and electronic equipment). European legislation plays a strong role in driving development and markets. Current ELT recovery and recycling methods achieve very high recovery rates (96%) but do not address the resource efficiency challenge; neither do they recover the valuable materials from which a tyre is made of. The products of current ELT recycling methods are low value and no microwave pyrolysis ELT plants are in operation.
Regarding long-term economic viability, the partners have several options: the process plant can be sold “as is”, components of the process can be individually sold or the individual products (oil, sulphur, S-AC, steel) can be sold. The consortium SMEs have decided that given (a) the lack of commercialised operational microwave pyrolysis plants despite intense interest, (b) the very diverse and wide applications of oil, sulphur and steel, (c) the potential of using the SULFREE system for pyrolysis of organic waste, they will promote the SULFREE technology to tyre recycling and tyre manufacturing as a complete ELT recycling process with valuable output products; oil and sulphur are an important component of tyres and S-AC is essential for reducing mercury emissions.
Additionally, the patented Carbon Activation Chamber, Fixed-bed HDS Reactor, H2S removal unit and sulphur retrieval unit and the Heat Exchange System will be promoted to Chemical Processing SMEs, active recycling. It is worth noting that since the Fixed Bed Reactor and the H2S and sulphur removal unit will be on a much smaller scale than those used in the refining and petrochemical industry and these sectors will not be targeted. The tyre sector and chemical processing sector are the first tier markets.
Benefits at the European and international level are: increased competitiveness in global tyre recycling markets by improving recycling rate and quality of output and by employing a novel technology, strengthen the EU’s position as the leader in tyre recycling. Furthermore reduced mercury emissions and control cost, increased competitiveness of tyre industry by reclaiming materials and lessening reliance on imports, increased use of biomass derived biofuel. There is also significant market potential outside the EU. In the USA every year more than 4.6 million tonnes of
ELT are recovered for recycling and annual mercury emissions are 232 tonnes. Since 2005, the “Clean Air Act” (US Environmental Protection Agency) is in effect, which legislates that by 2018 coal fired plants will have a cap of 15 tonnes/year mercury emissions. The US’s annual estimated cost damage due to mercury emissions is $580 million. The successful development of SULFREE technology would significantly improve the competitive position of European technology. The benefits for SME manufacturers and suppliers are vast. Once a European capability is established, EU companies may be offered the opportunity to expand into the North American, Chinese and Asia/Pacific markets, by selling and licensing the technology into those markets. SULFREE contributes to several EU policies: EC Directive 1999/31 (ban landfilled tyres), End of Life Vehicle Directive 200/52/EC, European Mercury Strategy, Renewable Energy Directive 2009/28/EC,
Directive 2003/30/EC “On the promotion of the use of biofuels or other renew-able fuels for transport”.
To further illustrate benefits of SULFREE for the end user, a commercial review was undertaken that considers small and large scale processes and those found in literature, under certain assumptions. The review clearly shows the commercial viability and improved profitability of SULFREE. Existing pyrolysis processes have their potential restricted by the high sulphur content of the pyrolysis oils, which is a major limitation. Refineries will often not accept such high sulphur content oils or offer a substantially lower price in view of additional costs for sulphur removal.
The economic impact of SULFREE is considered for the 4 years after project completion. It is expected that the overall financial savings generated from the successful implementation of
SULFREE will offer increased business opportunities for the participating SMEs and the EU recycling, tyre and biomass industry. The potential savings provide a strong incentive to use the research and SME developed technology on an international basis.
The prototypes will be fully commercialised within 12 months of project completion and the SMEs will have direct economic benefits. The total project investment is approximately €1.5 million with an additional €0.5 million for commercialization after the project’s end. The economic impact is calculated for the 4 years after project completion, based on the benefits presented above and for: annual inflation rate 2.8%, gross profit margin 50% (high-tech), 1 new job position per €120k.
Initial results and economic assessments are indicating that the Sulfree project has 2 potential income streams. The pyrolysis unit developed by HERI and the steam activation unit developed by Mervilab can produced both steam activated carbon black (Income €4 per KG for medium quality and €7 per KG high quality) and sulphur rich unrefined oil (approx. $55 per barrel) the extra units (Claus and amine stripper) would only give extra income in the form of $80 per barrel for refined oil, however the additional costs for these 2 units have been shown to only be attractive to larger SMEs with the return on investment timescales too long for smaller industrial companies.
Dissemination
A project website was created for the Sulfree process and can be found at www.sulfree.eu
One scientific publication was produced: Casos de éxito: Mervilab; Infoactis; Issue 25 (Abril-May-June 2014)
Even though no project workshop has been organised for Sulfree, Autico and Crumb attended an event from EU LIFE project DEPOTEC, a thermal pyrolysis solution for waste tyres, in November 2015. There were good opportunities for networking as the event attracted over 60 delegates.
Three conferences were attended:
Ecomondo. November 2014 in Rimini, Italy plus a poster ‘The SULFREE process’.
ACHEMA. June 2015 in Frankfurt, Germany
AMPERE. September 2015 in Krakow, Poland
Apart from conferences and the workshop there has been no direct contact with interest groups
A video of the Sulfree process has been made and is available for viewing on the project website www.sulfree.eu
Exploitation
The proof of concept for the Sulfree project has proved that this technology is now ready for progressing to the commercialisation of the process and during the project the following successes were achieved:
• Successful pyrolysis of rubber crumb using microwave technology
• One step “carbon black” production
• Modular design.
• Overall system designs for all sub-units to allow scale-up and installation at commercial end-user sites
• High efficiency process.
• Instant heating
• Internal reactor conveyance system
• Self-cleaning
• Stop/start – semi continuous
• Low odour (clean process), low tar production
• Fine carbon black particle size
• Production of “carbon black” and “low sulphur oil” with significant resale value to make the system commercially viable
• Identification of a suitable HDS catalyst to remove sulphur from pyrolysis oil
• Optimised HDS process for the recovery of sulphur-rich gas and low-sulphur oil
All partners in the consortium agreed to share the IP allowing each partner to develop their own exploitation strategy. The exploitation agreement was discussed and finalised at the final project meeting in Drogheda, Co. Louth, Ireland on the 23/24th February. The agreement that has been signed by all the SME partners is as follows:
Background
At the final project meeting in Drogheda, Co. Louth, Ireland on the 23/24th February 2016 three different exploitation routes were discussed by the Consortium. These three are;
1. To maintain development momentum by some of the SMEs applying for a Horizon 2020 “Fast Track to Innovation” follow-on Project, 2 years in duration, min. of 3 countries, 5 partners max. Consortium needs to be Industrial and capable of launching on the market, directly or indirectly via say further licensing.
2. To Form a Joint Venture Company, to enable all the SME rights to be united in one Commercial vehicle. The JV would establish a detailed business plan and be able to license the developed technology or raise funds via VCs/Banks etc. to exploit.
3. To agree further to the Consortium Agreement Clauses detailing each SME partner’s Sulfree Earnt Rights, which each partner is free to exploit the entire Sulfree Technology / Process / Results for themselves, on a non-exclusive basis, but with full rights to sub-license to third parties.
Discussions
After lengthy discussions on the three routes to exploitation above, the SME partners present (Crumb Rubber Ireland, Autico Ltd, Fricke und Mallah Microwave Technology GMBH, Material Y Equipos De Vidrio De Laboratorio SA, Note; WLB not present) decided on balance to accept exploitation route 3, i.e.
To agree further to the Consortium Agreement Clauses detailing each SME partner’s Sulfree Earnt Rights, which each partner is free to exploit the entire Sulfree Technology / Process / Results for themselves, on a non-exclusive basis, but with full rights to sub-license to third parties.
WLB have been separately informed of these discussions by e-mail.
Agreement of Sulfree SMEs
Hence it is agreed further to the signed Sulfree Consortium Agreement by signature below that each SME Partner will transfer all of their Sulfree Earnt Rights, Sulfree Intellectual Property (IP) and Sulfree IP Rights (IPRs) into a ‘common pool’ to unite the ownership of the IP and IPRs, so that each SME partner can be granted from this a non-exclusive, perpetual, worldwide, royalty free licence to exploit the Sulfree Technology / Process / Results (from the FP7 Sulfree Project No. 605246) for themselves, on a non-exclusive basis, as they wish. This agreement does give any SME partner the right to transfer their licence to other 3rd parties. Furthermore, the perpetual duration of this license is dependent on the SME partner carrying out (and evidencing) reasonable efforts to exploit the Sulfree Technology / Process / Results during a period of 2 years after the project end date. If the SME partner does not make efforts to exploit then their licence will expire 2 years after the end date of the Sulfree EC FP7 Project (i.e. 29 Feb 2016 plus 2 years).
For the avoidance of doubt, any party undertaking further development (i.e. further to this license scope) of the Sulfree Technology will fully own solely all rights to such further developments.
This agreement has been signed by all the relevant partners.
List of Websites:
Website www.sulfree.eu
Consortium:
The UK Health & Environment Research Institute. (Coordinator)
Contact: Simon Fawcett
Email: s.fawcett@pertechnology.com
Autico Ltd
Contact: Kevin Poole
Email: kevin.poole@autico.co.uk
Crumb Rubber Ireland Ltd
Contact: Leo Kerley
Email: leo@crumbrubber.ie
Fricke und Mallah Microwave Technology GMBH
Contact: Brais Vila
Email: b.vila@microwaveheating.net
WLB LIMITED
Contact: Marianna Vari
Email: mvari@wlbltd.eu
Innora Proigmena Technologika Systimata Kai Ypiresies Anonymi Etaireia
Contact: Vasilis Papadimitriou
Email: papadimitriou@innora.gr
Azienda Speciale Innovhub - Stazioni Sperimentali Per L'Industria
Contact: Gabriela Migliavacca
Email: migliavacca@ssc.it
Material Y Equipos De Vidrio De Laboratorio SA
Contact: Andres Del Alamo
Email: andres@mervilab.com
PUBLISHABLE SUMMARY
The Sulfree project sets out to convert low-value rubber crumb into high value products, including activated carbon and low-sulphur pyrolysis oils. Sulfree is a novel end of life tyre recycling process that employs microwave pyrolysis technology. Pyrolysis is thermal decomposition of organic materials in the absence of oxygen. Tyres due to their high carbon content are ideal candidates. Pyrolysis of end of life tyres results in a gas, a liquid (oil) and a solid carbon char (carbon black) fraction.
The major novelty of the project is the development of a complete desulphurisation process that reduces the sulphur content of the pyrolysis oils and gas, with sulphur recovery. This enables the sale of the pyrolysis oils as light sweet crude oil, currently sold at $90/bbl and estimated to reach by 2020 $125/bbl.
A working Sulfree rig was produced this was then used for optimising the process. During the process oil is continually condensing from the vapours produced during the pyrolysis process and collected. After five dispenses the excess hot carbon is ejected from the pyrolysis chamber and via a screw conveyor and is cooled and collected ready for dispensing. This screw conveyor and carbon cooling process is computer controlled via a dedicated computer programme.
The key measures of pyrolysis success are production of ‘dry’ carbon (i.e. fully-pyrolysed solid material that does not contain any pyrolysis oil) and recovery of the maximum yield of condensable pyrolysis oil. Both of these outputs are strongly affected by the pyrolysis temperature and the residence time in the pyrolysis chamber, along with the inertness of the atmosphere inside the pyrolysis zone, the mixing regime adopted and how the carbon and oil are cooled outside of the pyrolysis chamber.
The optimum temperature to achieve full pyrolysis of rubber crumb without unnecessary ‘over-heating’ was previously determined using thermogravimetric analysis and found to be 450 °C. This was therefore set as the target temperature for the reactor.
After each trial, the pyrolysis oil was recovered and the total volume determined. It was found that, for our system, the relationship between oil volume produced and degree of pyrolysis was almost linear (e.g. 85% pyrolysis of the crumb generated 85% of the theoretical maximum of pyrolysis oil) Changing operating parameters inside our chamber had very little impact on oil production and, as the most valuable component of our system is the carbon and not the pyrolysis oil, this production rate was not optimised further.
The design of the mixing blades ensures the walls of the chamber are kept clean, as the constant movement of the blades inside the chamber stops material building up on the walls. This is a significant advantage over many typical pyrolysis units. A second significant advantage of the Sulfree system is the lack of formation of waxes, which is a common problem in wholly thermal pyrolysis systems. It appears that microwave pyrolysis of rubber crumb significantly reduces the production of waxes, although the reason for this is unclear.
Energy and mass balance calculations have been carried out and the calculations estimate that the total cost of pyrolysis and oil treatment for 1 kilogram of crumb at steady state would therefore be 1 kilogram of crumb at steady state could be €1.62 (worst case scenario) or €0.17 at 90% efficiency of energy recovery from hydrogen.
During the project the following successes were achieved:
• Successful pyrolysis of rubber crumb using microwave technology
• One step “carbon black” production
• Modular design.
• Overall system designs for all sub-units to allow scale-up and installation at commercial end-user sites
• High efficiency process.
• Instant heating
• Internal reactor conveyance system
• Self cleaning
• Stop/start – semi continuous
• Low odour (clean process), low tar production
• Fine carbon black particle size
• Production of “carbon black” and “low sulphur oil” with significant resale value to make the system commercially viable
• Identification of a suitable HDS catalyst to remove sulphur from pyrolysis oil
• Optimised HDS process for the recovery of sulphur-rich gas and low-sulphur oil
The proof of concept for the Sulfree project has proved that this technology is now ready for progressing to the commercialisation of the process. All the SME partners have agreed an exploitation strategy.
A video of the working plant has is available for viewing on the Sulfree project website www.sulfree.eu
Project Context and Objectives:
SULFREE is a novel end of life tyre recycling process that employs microwave pyrolysis technology. Pyrolysis is thermal decomposition of organic materials in the absence of oxygen. Tyres due to their high carbon content are ideal candidates. Pyrolysis of end of life tyres (ELT) results in a gas (syn-gas), a liquid (oil) and a solid carbon char (carbon black) fraction.
An end of life tyre (ELT) is defined as a tyre that can no longer be used on vehicles and cannot be re-treaded anymore. All tyres (passenger cars, trucks and airplanes, two wheel and off-road vehicles) result in ELT. The bulk of ELTs results from car and truck tyres. ELT are classified as non-hazardous waste (75/442/EEC, Directive 91/156/EC).
Every year approximately 1.5 billion new tyres are sold worldwide and just as many are categorized as end of life. Despite an increase in the service life of tyres, these volumes are constantly rising due to the growing number of vehicles and increasing traffic worldwide. In Europe, in 2011 3.3 million tonnes of used tyres were generated. Of those, 173 tonnes were reused, 122 tonnes were exported, 286 tonnes were re-treaded and 2.7 million tonnes of ELT remained on the EU market for recovery and recycling, a 2.2% increase compared with 2009 and a fivefold increase over the last 17 tears. The annual cost for the management of ELTs is €600 million. There are also in the EU 5.7 million tonnes of old stockpiles (historic stockpiles) of used tyres that have been illegally dumped or stockpiled in landfills.
The main drive for the recycling and recovery of end of life tyres is the current EU legislation, with which all EU member states must comply. Legislation restricts the landfill of tyres and tyre waste and is an important factor that drives the industry to recycle tyres. However, despite the ban on landfilling (whole and shredded tyres), there are still the old tyre stockpiles. The legislative imperative for end of life tyre (ELT) recycling is defined by the following EU directives. The Directive on the Landfill of Waste (1999/31/EC) banned the landfill of certain whole and shredded tyres effective July 2003 (for whole tyres) and July 2006 (for shredded tyres. The End-of-Life Vehicle (ELV) Directive (2000/53/EC) sets a target of 95% recovery/reuse by 2015 for vehicles below 3.5 tonnes and indirectly setting targets for a part of ELT in the EU (10% of total ELT arise from ELV as defined by 2000/53/EC). To achieve these ambitious targets, ELV processors require the tyres to be recycled.
World tyre demand is forecasted to rise 4.7 percent per year through 2015 to 3.3 billion units, despite the current economic uncertainty. Global car tyre sales are expected to increase from 290 million passenger car tyre sales in 2010 to 400 million units by 2020 and replacement car tyre sales from 760 million units in 2010 to 1.2 billion units by 2020. The large motor vehicle tire market will accelerate its growth through 2015, advancing to 1.9 billion units. The Asia/Pacific region is by far the largest market for tires, accounting for over half of global tire consumption8.
This increased demand will result in a directly analogous, significant increase in the number of ELT in the EU and USA but also in new and emerging markets (e.g. China, India). Currently, the global output for ELT is 1.5 billion (2011), and will rise as high as 3 billion in 2015.
ELT derived products are typically of low value and do not take advantage of the fact that tyres consist of valuable resources (rubber – carbon, oil, steel, sulphur) and are also themselves a valuable commodity. The average price for a passenger tyre ranges from €60 to €300 and according to industry experts, the cost to produce a tyre is: 30% raw materials, 30% CAPEX (expenditures creating future benefits overhead, environmental cost), 30% labour and 10% profit.
The SULFREE process is the following. The steel content of the tyre is removed before shredding and the tyres are cleaned if needed (e.g. to remove residual chorine); this is standard procedure for the tyre crumb providers. The steel is removed before shredding and pyrolysis to improve the quality of the steel and to extend the operational lifetime of the tyre shredding machinery. The machinery and the crumb will be provided by one of the SME partners, as this is a mature area where no R&D efforts will be applied. The tyre crumb is fed at a rate of 125 kg/h (1000 tyres/day) to the pyrolysis chamber via a mixer and screw feeding system; this design enables the constant mixing of the tyre crumb. The microwave heating system operates at 600°C to pyrolyse the crumb to gas, oil and carbon char. The pyrolysis products are then separated and the oil and gas are cooled and combined to a vapour and are fed to the fixed bed reactor at a temperature of 250°C. The vapour undergoes hydrodesulphurisation (HDS) in the fixed bed reactor, using specially selected catalysts that will be identified during the R&D activity. Following this, the vapour is condensed and the oil with less than 0.2 % sulphur is recovered. The gas, now rich in hydrogen sulphide (H2S), is cooled down to 44°C and is passed through a monoethalomine (MEA) stripper to hold the H2S. The elemental sulphur is then recovered using the Claus process (recovery rate at least 95%). The gas then can be burned to cover the heat and energy requirements of the process. The carbon char is inputted to the activation chamber at a temperature of 400°C and at a rate of 35kg/h, where it is activated using steam, in a low oxygen environment.
The major novelty of the project is the development of a complete desulphurisation process that reduces the sulphur content of the pyrolysis oils and syn-gas, with sulphur recovery. This enables the sale of the pyrolysis oils as light sweet crude oil, currently sold at $90/bbl and estimated to reach by 2020 $125/bbl.
The aim is to produce from ELT (a) oil with low sulphur content (less than 0.2%) suitable for use as sweet crude oil and in accordance with EU regulations (b) high quality sulphur-impregnated activated carbon (S-AC) that can be used in high value applications (e.g reduce mercury emissions), (c) elemental sulphur and (d) steel recovered from the tyre before pyrolysis.
The pyrolysis sulphur rich carbon black is activated to high quality sulphur-impregnated activated carbon using a one-step procedure, thereby increasing the carbon black’s commercial value: typical prices for S-AC are €7.00 - €12.00/kg.
An additional novelty is the process’s energy management. Pyrolysis, desulphurisation and steam activation are all energy intensive. By integrating them and using waste heat from the system and the sulphur-low syn-gas, the energy requirements can be fulfilled internally by at least 60%. This large energy saving results in significant cost savings.
The SULFREE plant will have an input capacity of 1,000 tyres per day, equivalent to 125 kg/h, with a 90% material recovery. The following table summarizes the outputs versus the average end of life tyre composition, which is the process’s raw material.
To successfully achieve the SULFREE process and produce the desired end products, the following scientific and technological objectives are set.
Scientific
1. Numerical modelling of the pyrolysis process to optimize conditions and yields. Fully characterize pyrolysis oils produced under different operating conditions and produce a parametric model, with attention to the remaining sulphur fractions. Selection of best suited desulphurization method based on the characterization of pyrolysis oils.
2. Understand how process parameters and fixed bed reactor size affect effectiveness. How to successfully construct an FBR at a smaller size while retaining required temperature and pressure to ensure optimal H2S formation.
3. Enhance our understanding of H2S removal from the gas stream using MEA (Monoethanolamine): initial H2S concentration, heat, pressure and steam requirements, effectiveness, MEA regeneration
4. Enhance our understanding of how operating conditions (e.g. concentration, contact time, reaction temperature, number of stages) affect the Claus process for recovering 95% of elemental sulphur, from the resulting acid gases after MEA treatment.
5. Enhance our understanding of how to control microwave processing conditions such as energy input, wave scattering, and pulse duration and how moisture conditions and degree of reaction effect microwave heating.
6. Enhance our understanding of how operating conditions during manufacture affect final S-AC quality; surface area of the activated carbon, mechanical properties, Hg absorption kinetics, Hg absorption capacity and knock on effects on final disposal or reactivation.
7. Enhance our understanding of the total energy requirements of the process and use waste heat and the syn-gas for fulfilling them in-situ, at least by 60 – 70%.
Technological
1. Input capacity of 1000 tyres per day (125 kg/h)
2. Oil with sulphur content less than 0.2% (sweet crude oil type) and a yield rate of 40% per tonne of tyres processed.
3. S-AC with an Hg capacity of 1.5mg/g able to achieve at least a 93% reduction of Hg in ratio’s of 9 mg S-AC/m3 flue gas and a yield rate of 36% per tonne of tyres processed.
4. A yield rate of 12% steel per tonne of tyres processed.
5. A yield rate of 1.4% of elemental sulphur per tonne of tyres processed.
Their successful realisation will result in the development and manufacturing of: (a) the pyrolysis chamber with a combined microwave heating unit and mixer and screw design for inputting the tyre crumb, (b) the one-step carbon black steam activation unit, (c) the fixed bed reactor for HDS of the pyrolysis oil, (d) the MEA stripper for removing the H2S from the gas, with sulphur recovery, (e) the heat exchange and energy recovery unit and (f) the automation system and control software for the SULFREE plant. Their successful integration will result in the complete SULFREE plant, capable of meeting the technological objectives, which is the integration objective.
Project Results:
The Sulfree project sets out to convert low-value rubber crumb into high value products, including activated carbon and low-sulphur pyrolysis oils. Sulfree is a novel end of life tyre recycling process that employs microwave pyrolysis technology. Pyrolysis is thermal decomposition of organic materials in the absence of oxygen. Tyres due to their high carbon content are ideal candidates. Pyrolysis of end of life tyres results in a gas, a liquid (oil) and a solid carbon char (carbon black) fraction.
The major novelty of the project is the development of a complete desulphurisation process that reduces the sulphur content of the pyrolysis oils and gas, with sulphur recovery. This enables the sale of the pyrolysis oils as light sweet crude oil, currently sold at $90/bbl and estimated to reach by 2020 $125/bbl.
Work Package 1 “Development of Pyrolysis Unit”
The first task was to fully specify the microwave chamber design and the microwave heating system in order to achieve a sufficient heating rate to process up to 125 kg/h tyre crumb at up to 600 °C. The size of the chamber was largely governed by the former, while the microwave energy input was controlled by the latter. Due to the high heat of the system and corrosive nature of the vapour, 316 stainless steel was chosen as the construction material. Consideration was given to materials of construction for the microwave windows and the microwave power required achieving the necessary heating. Computational calculations showed that 600 °C could be achieved using 10 kW of microwave power delivered over 25 minutes. Five 2 kW magnetrons were therefore specified. Using these figures and considerations, the processing chamber and microwave heating systems were designed to achieve a minimum processing throughput of 1 kg/min rubber crumb, or 60 kg/h. The final design has been fully reported in “Deliverable 1.1 Complete specification of microwave pyrolysis unit”
Considerable thought was given to the internal mixing and conveying system within the chamber, as calculations showed good mixing would be critical to achieve full pyrolysis of the rubber crumb. A number of designs were considered and rated on their complexity of manufacture, ease of use and control and overall suitability to the system. Once the design was selected, further consideration was given to seals, bearings and motors, all of which were specified to complete the design.
The most cost-effective method of producing an inert atmosphere is to use nitrogen gas. A system was therefore developed to introduce nitrogen gas into the chamber at specific inlet ports to optimise rubber pyrolysis and also protect key components of the system from heat and carbon char; the motor chamber was cooled with a constant flow of nitrogen in order to protect the motor itself; the ceramic windows installed ahead of the magnetrons were flushed with nitrogen to generate a curtain of gas to help to resist the deposition of carbon onto the windows to stop microwave absorption and cracking of the ceramic; the infra-red temperature sensors were also flushed with nitrogen, again to stop the build-up of soot on the sensors and the generation of false readings; the inlet hopper was flushed with nitrogen to stop oxygen ingress into the system. The constant positive pressure of nitrogen within the system ensures oxygen ingress into the pyrolysis zone cannot occur. This design also removed the requirement for an airlock system, making the unit simpler to construct, operate and maintain.
Having completed the design specification for the chamber, the unit construction began.
Work Package 2 “Identification of optimal pyrolysis processing conditions”
In order to limit the number of optimisation experiments required for the pyrolysis system, detailed lab-scale pyrolysis experiments using rubber crumb in thermogravimetric analysis were undertaken to determine the optimum pyrolysis temperature. These experiments showed that complete pyrolysis of the rubber could be achieved at 450 °C, meaning that the prototype rig could operate at a lower temperature than the 600 °C originally planned. This had a number of benefits, including a lower energy requirement for the system and, in theory, faster processing times and thus throughput rates. By setting 450 °C as the processing temperature, the number of optimisation variables was also reduced, making the Design of Experiments (DoE) process easier. The main variables were therefore identified as:
• Rubber crumb size
• Temperature ramp rate
• Temperature hold time
Having set up the DoE plan the next challenge was to operate the pyrolysis system.
Work Package 3 “Development of vapour processing unit and activation chamber”
The original plan for the vapour processing unit was a vapour compressor that could take the hot gas directly from the pyrolysis chamber and compress it for injection into the hydrodesulphurisation (HDS) unit. Much research was carried out to find a suitable, commercially-available system, but it became apparent that the original plan would not be viable within the Sulfree project. To begin with, most commercial compressors could not operate at the outlet gas temperature specified and, of those that could; they would be operating at their temperature limit. Also, in order to achieve the pressure required for the HDS unit, a two-stage compressor was required.
The carbon activation chamber and steam injection systems were fitted directly to the bottom outlet of the pyrolysis chamber.
Work Package 4 “Development of fixed-bed reactor”
Catalytic hydrotreating (HDT) is a technique used extensively in the petroleum industry to remove impurities, such as sulfur, nitrogen, oxygen, polynuclear aromatics, and metal-containing compounds (mainly vanadium and nickel). Depending on the nature of the feedstock and the amount and type of the different impurities, specific hydro-treating processes have been developed. The reactions occurring during hydrotreating are hydrodesulfurisation (HDS), hydrodenitrogenation (HDN), hydrodeoxygenation (HDO), hydrodearomatisation (HDA), hydrodemetallisation (HDM), and hydrodeasphaltenisation (HDAs). Concurrently, the average molecular weight of the oil is lowered as a consequence of hydrocracking (HDC) reactions, which can happen without a substantial loss in liquid product yield, as in the HDT of light distillates, or with moderate or severe reduction of molecular weight, such as in the case of heavy feeds.
The severity of reaction conditions depends on the type of feed and on the product quality desired. In general, the higher the boiling point of the feed, the higher the reaction severity.
Hydrotreating processes are mainly conducted on the oil fractions (i.e. after the separation of crude oil to its derivatives such as gasoline, kerosene, heavy and light gas oil and other oil fraction), and not on the full crude oil. This means that a large part of the contaminants, such as sulfur, nitrogen, metals, aromatics and asphaltenes will be deposited at the bottom of the atmospheric and vacuum distillation column. Hydrotreating of each section separately is fairly easy. However, the crude oil hydrotreating process is regarded as a large and difficult challenge since crude oil contains many compounds and complex structures, in addition to multiple phases. In addition, crude oil hydrotreating in the presence of the asphaltenes containing a large component of sulfur and metals (which poison the active sites of the catalyst) is one of the more difficult and important problems.
The main sulfur components of liquid fuels are thiols, sulfides, thiophene and alkylthiophenes, tetrahydrothiophene, thiophenols and benzothiophene. Alkylthiophenes include three and four carbon atom-substituted thiophenes (C3- and C4-thiophenes), thiophene sulfur represents a large fraction of the total sulfur content in light fuels (60 wt% and over). The sulfur compounds in the naphtha fraction, obtained from waste tyre pyrolysis, have previously been reported to be composed of methyl-, dimethyl- and ethylthiophene, trimethyl- and isopropylthiophene, and tert-butylthiophene including benzothiazole. The rates of desulfurisation of thiophene, tetrahydrothiophene and n-butanethiol over various catalysts including alumina-supported cobalt–molybdenum have been investigated in the literature, disclosing that the reactivities of thiophene and tetrahydrothiophene were similar while that of n-butanethiol was much higher (15–40 times). The identification and quantification of these sulfur compounds are not via conventional analysis and they are even more difficult to study when the chemical matrix is very complex and largely unknown, as for pyrolysis oils.
The HDT process is generally carried out in fixed beds (FBRs), moving beds (MBRs), expanded or ebullated beds (EBRs), and slurry bed (SBRs) reactors. The principle of operation of these three groups of reactors is very similar, but they differ in some technical details. Figure 1 below shows schematic representations of the reactors used for catalytic hydrotreating.
Figure 1: Schematic of hydrotreating processes
FBR reactors are utilised mainly for hydrotreating of light feeds, such as naphtha and middle distillates, but they are also used for hydrotreating of heavier feeds, such as petroleum residues. However, when the feed contains large amounts of metals and other impurities (e.g. asphaltenes), the use of FBRs has to be examined carefully, according to the catalyst cycle life. Alternatively, MBR and EBR reactors have demonstrated reliable operation with difficult feeds, such as vacuum residues. When hydrotreating petroleum feeds, the life of the catalyst is crucial to retaining its activity and selectivity. Depending on the feed, the catalyst life may vary on the order of months or years. It is then clear that the timescale of deactivation influences the choice of reactor.
Sulfur compounds present in naphtha are generally easy to remove. That is the reason that only an HDS catalyst is required for sulfur removal in naphtha. However, when processing straight-run gas oil (SRGO), the refractory sulfur compounds are more difficult to remove, making deep HDS for ultra-low sulfur diesel (ULSD) production difficult to achieve. In addition, most of the time, SRGO is blended with light cycle oil (LCO) from catalytic cracking units (FCC), and both are fed to the hydrotreater. Apart from sulfur, LCO also contains high amounts of nitrogen and aromatics, which make the hydrotreating even more difficult, since they either compete for catalytic active sites or consume large amounts of hydrogen. To address this problem, multi-bed systems with different catalysts have been proposed. Also, hydrogen is introduced between the beds as a quench because the reaction is exothermic. The heat released in light feed HDT is relatively low, so that quenching is not necessary and HDT units are designed with just one reactor containing a single catalyst bed. However, for heavier feeds, multiple catalyst beds with cooling in between are used. Multi-bed configurations with a hydrogen quench system are usually employed for hydrotreating of FCC feeds (a blend of heavy atmospheric gas oil and light and heavy vacuum gas oils) and heavier feedstocks.
The bench-scale reactor used in the Sulfree project is an automatic, computerised high-pressure catalytic reactor which includes the valves and process layout inside a hot box to avoid possible condensation of volatile products, while also preheating the reactants efficiently. This equipment has been designed as a universal basic unit that can be modified.
The basic unit includes the reactor (up to 1000 ºC) and valves inside the hot box, 3 mass flow controllers (MFCs), a micro-regulation pressure control system (up to 100 bar +/-0.1 standard), a high-pressure liquid/gas separator with the lowest dead volume available and all common elements designed to work in continuous mode. A six-way valve makes it possible to bypass the reactor before reaction starts, while stabilisation and feed analysis are taking place.
The main characteristics of the equipment are:
• Maximum working pressure 100 bar.
• All layout inside hot box made of SS304 with hot air convector. Maximum recommended temperature 200ºC ± 1ºC. Stable full system temperature avoids cool or hot points on overall layout system.
• Reactor furnace in SS304, with radiant ceramic fibre heaters. Maximum temperature 1100ºC ± 2ºC. Very low thermal inertia (no overshoot) and good temperature distribution.
• Standard Autoclave Engineers tubular micro-reactor in SS316, I.D. = 9.1 mm, L = 300 mm, max. recommended SS316 temperature 650 ºC @ 100 bar or 800 ºC @ 1 bar. Porous plate: 20-40 microns. An analogue reactor in Hastelloys allows increasing the max. working temperature up to 800 °C @ 100 bar or 1200 °C at lower pressure.
• Thermocouple Φ= 1.5 mm, Incoloy, directly inside catalyst bed, without thermowell, for fast response (0.2 sec).
• VICI-Valco 6-port/2-position valves, 280 ºC@100 bar VALCO special HT+HP design, to bypass reactor.
• 3 Modbus mass flow controllers, Hi-Tec Bronkhorst, precision 1% FS, repeatability 0.1%, with process compatible elastomers. DIGITAL Modbus communications. Mass flow controllers are for pure hydrogen (used in HDS process), one for H2S/H2 mixture (used in pre-sulfiding of the catalyst) and one for nitrogen (for purging).
• Shut-off valves and check-valves (Kalrez elastomer) for each MFC, and turbulent flow gas mixer.
• Condenser/separator for liquids based on thermoelectric effect (0 to 60 ºC controlled temperature) without external chiller. Patented all-in-one system with very low dead volume.
• Liquid level micro-sensor on the L/G HP separator, based on the capacitive effect of dielectric liquids, from hydrocarbon range (ε=1.1) to water range (ε=80). Dead volume less than 1 cm3
• Filters at reactor inlet and outlet (low dead volume and high surface capacity) to prevent particles in the system.
• 1/8” SS316 1.5 m heated transfer line to GC, 150 ºC-300 ºC temperature-controlled.
• micro-GC for on-line gas phase analysis.
• Power management for temperature control using advanced phase angle proportional control devices that allow faster and more stable temperature control without overshooting.
• The equipment has several independent safety levels: automatic switch-off in the event of any trouble with liquid level, pressure or temperature, providing a security system separate from the PC. User can specify and define the functions for alarm actions and interlocks, configuring and programming them by touch screen or computer.
A commercial hydrodesulphurisation unit was used that could 0.6kg of vapour per hour, generating oil with less than 0.2% sulphur. This unit was initially trialled with a sample of pyrolysis oil that was obtained from a local supplier and found to be suitable for further trials. The throughput is a maximum of 1kg per hour (well above the required 0.6kg of vapour per hour) and the first trial with non-specific pyrolysis oil generated desulphurised oil with less than 0.2% sulfur with only minor optimisation.
WP5: Development of unit for hydrogen sulphide removal and elemental sulphur recovery
The Sulfree system constitutes a highly innovative system which redefines the tyre recycling process. Through a sophisticated chemical process, the designed plant is able to pyrolyse the crumb rubber retrieving high-quality oil as well as steam activated carbon while re-using a significant amount of energy produced thereby achieving high energy efficiency. Figure 2 illustrates the high-level architecture of the system highlighting the hydrogen sulphide removal and Claus units.
Figure 2: High-level overview of the Sulfree process
The hydrogen sulphide removal (amine) and Claus units are responsible for recovering the sulphur contained in the tyre crumb and yielding it as a product in its elemental form.The off-gases of the hydrotreater of the Sulfree plant will be processed in the amine unit for removal of H2S. The sweetened gas product of the amine unit may be recycled via a compressor to the hydrotreater, in order to save expensive hydrogen, or burnt to generate heat. The sour gas effluent of the amine unit (mainly H2S), is fed to the Claus unit, where it is converted to elemental sulfur.
Theoretical mass balance calculations were carried out in order to understand energy flows for each of the streams into the amine and Claus units. The figures for the amine stripper stage were determined by experiment in the HDS stage and reported previously. Using these figures, it is possible to calculate the mass balances for material flows into the Claus unit.
The mass balance data proved that the bulk of the gas that enters the amine unit post-HDS is hydrogen that has not been used in the reduction process. The amine unit strips out the hydrogen sulphide, allowing the remaining gas to be returned to the HDS process for recycling. A percentage of this hydrogen is extracted by the amine however, which enters the Claus unit and is burned during the recovery of sulphur.
Using data from the HDS stage of the Sulfree process, mass flows have been determined for a range of species into the amine stripper unit and calculated for inputs into the Claus unit. These mass flows have been converted into energy flows for the amine and Claus units, showing a considerable positive energy balance for these two systems when they are combined. This energy could be recovered and used in the rest of the Sulfree system to achieve steam activation of the carbon black and pre-heating of input streams to the HDS and pyrolysis chamber.
WP6: Assessment of energy use and recovery
A significant amount of study was already given to energy flows in the amine and Claus units as, whilst amine extraction of hydrogen sulphide (H2S) requires energy to regenerate the amine, huge quantities of heat are generated in the combustion of H2S to generate elemental sulphur along with the production of super-heated steam. These calculations suggest that the majority of the energy demands of both the steam activation of carbon black and the regeneration of the absorbing amine in the stripper unit could be covered by the combustion of extracted H2S. These basic calculations have allowed us therefore to focus on the energy demands of pyrolysis and hydrodesulphurisation (HDS) to suggest how energy efficient the whole Sulfree process could be.
Calculations show that the energy produced by the Claus units, combined with recoverable energy from cooling units around the system should be sufficient to cover the energy demands of the amine and steam activation units in the Sulfree system. This therefore leaves the pyrolysis unit and the HDS unit consuming energy. Working on the basis that these units have reached steady-state operation at optimum conditions, calculations have been carried out to show that the total heat energy demands for the two processes are between 15.52 and 1.65 kWh, depending on whether heat energy is recovered from process hydrogen. The majority of this energy is required to heat the hydrogen for HDS, with only a small component coming from the energy demands of pyrolysis. Also, the calculations do not consider the need to pressurise the pyrolysis oil, which will increase the overall energy cost associated with HDS. With such a large variation in energy demands, the calculations show it would be critical to recover heat from the spent hydrogen in order for HDS to be commercially viable as part of the Sulfree system.
The heat demanded in the various pieces of equipment will be delivered in the form of 3.5 bars saturated steam, (saturation temperature = 148oC).
➢ The steam will be generated in the heat exchangers of the Claus units, by cooling the thermal stage off-gas.
➢ The balance steam will be created by a dedicated boiler, which will be fed by the sweetened gas of the amine unit and natural gas.
• The steam will be utilized in:
o The reboiler of the amine regenerator,
o The interheater exchangers of the Claus unit’s catalytic stages and
o The carbon activation subunit.
The sweetened gas from the amine unit flows to the fuel gas drum, together with the incondensable gaseous products of the pyrolysis reactor.
The pressure of the drum is kept steady by a split range pressure controller that regulates both the valve of the make-up natural gas and that of the vent to safe location valve. In case of excessive pressure rise, the pressure vessel will be protected by the dedicated pressure relief valve.
The fuel gas product of the drum flows under flow control to the Claus unit thermal stage and to the boiler of the plant. A separate gas flow controller has been provided to support future users. Especially for the boiler, the set point of the fuel gas flow controller is reset by the pressure controller output of the unit’s steam drum.
The steam produced by the Claus unit’s process gas coolers enters the steam drum. The pressure of the steam drum is kept constant by its split range pressure controller. The controller may lower excessive steam pressure, by venting steam to safe location, or increase pressure, by cascading a higher fuel gas flow set point to the firing controller of the boiler.
The drum’s steam is consumed in the reboiler of the amine regenerator and the interheaters of the two catalytic Claus stages, under temperature control.
Steam is also provided under flow control to the carbon activation subunit of the pyrolysis reactor.
In case the pressure of the steam drum increases excessively, the dedicated pressure relief valve will vent steam to safe location, protecting the pressure vessel.
The objective of the previously described control system is the minimization of the energy cost of the pyrolysis, amine and Claus units. This scope is achieved by utilizing preferentially the steam produced as a by-product of the Claus unit and using the boiler only to close the steam mass balance.
At the same time, the fuel gas produced in the plant is used preferentially in the boiler to produce steam and imported natural gas is used only to close the heat balance.
Thus, heat is transferred from the equipment with a surplus, in the form of saturated steam, to the equipment with a deficit. In the same time, natural gas import is minimized in favour of the self-produced fuel gas.
The control system described is based on classical PID control and traditional advanced control, (split range and cascade control). Thus it can be seamlessly integrated in the basic control software implemented for the whole Sulfree project plant, in the same PLC.
From the energy and mass balance calculations that have been carried out and the calculations estimate that the total cost of pyrolysis and oil treatment for 1 kilogram of crumb at steady state would therefore be 1 kilogram of crumb at steady state could be €1.62 (worst case scenario) or €0.17 at 90% efficiency of energy recovery from hydrogen.
WP7: Development of process and supervisory control system
The Sulfree project sets out to convert low-value rubber crumb into high value products, including activated carbon and low-sulphur pyrolysis oils. However, in order to convert the output vapours and carbon from the pyrolysis process into valuable products, the carbon must be steam-activated, and the pyrolysis oils must undergo hydrodesulphurisation to produce a low-sulphur oil.
Hence, the whole process is constituted of six units mostly in series and specifically:
1. Pyrolysis unit
2. Steam activation unit
3. Hydrodesulphurization unit
4. Hydrogen Sulphide removal
5. Elemental sulphur recovery
Gas and liquid treatment, constituted by units 3, 4 and 5 is a critical point. The plant schemes for the whole process including all the plant units were defined in the form of P&IDs.
The Sulfree system completely redefines the tyre recycling process. Through a sophisticated chemical process, the designed plant is able to pyrolyse the crumb rubber retrieving high quality oil as well as steam activated carbon while re-using a significant amount of energy produced thereby achieving high energy efficiency. Figure 2 illustrates the high-level architecture of the system highlighting the pyrolysis unit whose control forms the bases of the optimal controller described in this deliverable report. The H2S removal and Claus units are also highlighted as their control is also part of the optimal controller due to the great impact of their operation on the system’s overall productivity and running cost.
The Hydrogen-sulphide removal and Claus units are responsible for recovering the sulphur contained in the tyre crumb and yielding it as a product in its elemental form. The off-gases of the hydrotreater of the Sulfree plant will be processed in the amine unit for removal of H2S. The sweetened gas product of the amine unit may be recycled via a compressor to the hydrotreater, in order to save expensive hydrogen, or burnt to generate heat. The sour gas effluent of the amine unit (mainly H2S), will be fed to the Claus unit, where it will be converted to elemental sulfur.
Each of the Sulfree units is controlled by a local controller which is based on traditional PID control techniques. The local controllers are responsible for keeping the individual units operating around specific desired values. On top of the local controllers, an energy efficiency controller is used to jointly optimise the operation of the amine and Claus unit operation in order to locally achieve maximum energy efficiency for the Sulfur Recovery subsystem.
Finally, the optimal operation of the entire plant is ensured by the optimal controller lying on the top layer of the Sulfree control architecture. The overall Sulfree plant consists of multiple different components. Each of these components is controlled by a local controller which is based on traditional PID control techniques. The local controllers are responsible for keeping the individual units operating around specific desired values.
However, the optimal operation of the entire plant requires that all the individual process parameters are jointly optimised. This means that the optimal controller encompasses both the sulfur recovery process as well as the pyrolysis system. The latter lies at the core of the Sulfree plant and its operation parameters are critical as they greatly impact the yield of the plant with respect to the various products (sulphur, carbon and oil) as well as the energy consumption.
As a consequence, in order to ensure optimal operation, a two-layer control architecture is employed. The bottom layer is responsible for maintaining the operation parameters of each unit at the desired values while the top layer adjusts these values in order to achieve maximum efficiency with respect to a specific objective function.
The energy efficiency controller described above emerges as an intermediate control layer; it jointly optimises the operation of the amine and Claus unit operation in order to locally achieve maximum energy efficiency. It is therefore integrated in the overall control architecture as a layer in between the local controllers and the global optimal controller as illustrated in Figure 3. Note that only the pyrolysis, H2S removal and Claus units are considered as they have the highest impact in the Sulfree plant’s operation.
Figure 3: Overall Sulfree Control Architecture
WP8: Prototype operation and optimisation
The individual units were integrated together to provide the working Sulfree rig (Figure 4).
Figure 4: The working Sulfree rig
The pyrolysis process has been run at the facilities of HERI. During the process oil is continually condensing from the vapours produced during the pyrolysis process and is collected (Figures 5 and 6) and sent for testing.
Figure 5: Oil condensed and flowing Figure 6: Oil being collected in collection bottle
After five dispenses the excess hot carbon is ejected from the pyrolysis chamber and via a screw conveyor and is cooled and collected ready for dispensing. This screw conveyor and carbon cooling process is computer controlled via a dedicated computer programme (Figure 7).
Figure 7: Computer control process for screw conveyor and carbon cooling process.
Carbon has also been collected and sent for testing to determine its BET value.
A video of the working plant has is available for viewing on the Sulfree project website www.sulfree.eu
The key measures of pyrolysis success are production of ‘dry’ carbon (i.e. fully-pyrolysed solid material that does not contain any pyrolysis oil) and recovery of the maximum yield of condensable pyrolysis oil. Both of these outputs are strongly affected by the pyrolysis temperature and the residence time in the pyrolysis chamber, along with the inertness of the atmosphere inside the pyrolysis zone, the mixing regime adopted and how the carbon and oil are cooled outside of the pyrolysis chamber.
The optimum temperature to achieve full pyrolysis of rubber crumb without unnecessary ‘over-heating’ was previously determined using thermogravimetric analysis (TGA, Figure 5) and found to be 450 °C. This was therefore set as the target temperature for the reactor.
Building on from the results earlier in the project, the temperature of 450 °C was therefore aimed for using microwave power. It is important to achieve this temperature as quickly as possible inside the pyrolysis zone, in order to achieve full pyrolysis of the rubber and minimise the production of non-condensable gas. The microwave power input was therefore adjusted over a range from 50% to 90% of full power and the resulting temperature profiles recorded. These first trials demonstrated that, at 50% of full power, the temperature of 5kg of crumb inside the chamber could not be raised to 450 °C within the target residence time of 25 minutes. Raising the input power to 75% of maximum allowed us to achieve the target temperature, but this took over 20 minutes and the recovered rubber after treatment was not fully pyrolysed. Raising the power again to 90% of maximum allowed us to heat the rubber crumb to 450 °C within 20 minutes, therefore providing a hold time of 5 minutes in the final heated zone. The recovered material after treatment at this temperature was 75% pyrolysed on average.
Figure 5: TGA trace for pyrolysis of rubber crumb at various temperatures
To improve this degree of pyrolysis without increasing the hold time or energy input, the mixing regime was investigated. The first trials had minimal mixing, with only one mix after 3 minutes heating and a mix while the material was being moved between heated zones. A range of mixing trials were carried out and the recovered carbon material analysed for completeness of pyrolysis. It was found that, although mixing had only a small effect on pyrolysis efficiency, 85% pyrolysis could be achieved if the material was mixed every minute, along with being mixed during transfer between microwave zones. This is not particularly surprising, as mixing ensures that material that is not exposed to microwave energy (as it is within the bulk material or outside of the microwave treatment window) is moved and exposed to the energy.
It was suggested that increasing the power output of the magnetrons still further to 95% of total power would drive the pyrolysis to completion. However, trials at this power output led to significant problems with the rig, as the magnetrons consistently overheated and cut out. Damage was also caused to the power boards of the magnetrons.
After each trial, the pyrolysis oil was recovered and the total volume determined. It was found that, for our system, the relationship between oil volume produced and degree of pyrolysis was almost linear (e.g. 85% pyrolysis of the crumb generated 85% of the theoretical maximum of pyrolysis oil) Changing operating parameters inside our chamber had very little impact on oil production and, as the most valuable component of our system is the carbon and not the pyrolysis oil, this production rate was not optimised further.
Although we could not achieve complete pyrolysis of 5kg of feed crumb within 25 minutes as we originally hoped (1kg/min throughput), slowing the process down to 40 minutes (0.625kg/min) allowed us to achieve over 95% pyrolysis of the input carbon. This is a suitable level to use in the carbon activation stage, as the heat used in the activation process will complete the pyrolysis without major detriment.
Analysis of the recovered carbon showed it to have a BET adsorption volume of 60 m3/g as recovered after pyrolysis. The entry grade for activated carbon is around 400 m3/g. To obtain carbon with a relatively high adsorption capacity after pyrolysis was also unexpected and suggests that further activation should lead to high-quality activated carbon.
Once the operating parameters to achieve optimum pyrolysis had been determined, consideration was given to the optimum operation of the rig itself. This included parameters such as inert gas flow rate into each section of the rig, flow of cooling water and consideration of cleaning regimes.
The flow rate of inert gas to purge the system and protect the microwave windows and thermal sensors from soot was supplied from the same feed. The percentage of flow to each section of the rig was therefore investigated to minimise total gas input whilst ensuring the temperature sensors and microwave windows were kept soot-free (thus reducing total operating costs.) It was determined by experiment that a flow rate of 5 litres/minute total flow across the microwave windows (i.e. 1l/min across each individual window) and a total flow of 3 litres per minute across the thermal sensors protected these components from soot; even after numerous runs in the chamber the sensors and windows showed only minimal soot contamination at these flow rates. A total gas flow of 20l/min into the chamber was therefore used to purge the system and keep it inert. It may be possible to reduce this value still further, but this flow rate is already low and unlikely to have a significant impact on operating costs.
Cooling water was supplied from a chiller unit, which controlled the temperature at 8 °C and a flow rate of 60l/min. This water was used to keep the condenser/coalescer system cool and ensure recovery of pyrolysis oil. Analysis of the non-condensable gas from the system showed that no further pyrolysis oil could be condensed, indicating that the chiller was operating efficiently. As the chiller water was taken from a bulk feed, this temperature and flow rate was not adjusted.
Finally, considering cleaning requirements, the rig was opened up to inspect the internal surfaces, stirring blades and valves. Surprisingly, even after prolonged use, the inside of the chamber and paddles remained free of soot or waxes and, as described above, the windows and sensors remained relatively soot-free.
We believe it is the design of the mixing blades that ensures the walls of the chamber are kept clean, as the constant movement of the blades inside the chamber stops material building up on the walls. This is a significant advantage over many typical pyrolysis units. A second significant advantage of the Sulfree system is that lack of formation of waxes, which is a common problem in wholly thermal pyrolysis systems. It appears that microwave pyrolysis of rubber crumb significantly reduces the production of waxes, although the reason for this is unclear.
After numerous teething troubles with the pyrolysis unit, complete pyrolysis of rubber crumb has been achieved but at a slightly lower throughput rate than originally planned. This is mainly down to issues with the magnetrons used in the process. We are confident that, with modification of these units, the throughput of rubber crumb in the Sulfree process could be increased. Recovered carbon is free from pyrolysis oil and has a BET gas adsorption capacity of 60 m3/g without further steam/chemical activation.
For the pyrolysis oil, the goal to produce an oil with less than 0.2% of sulphur has been achieved and exceeded in all the tests. The produced pyrolysis oil has properties typical of a light fuel oil for heating or industrial applications. Our HDS unit can process 0.6kg of vapour per hour as originally specified.
After extensively testing at the RTD performer’s site (HERI), the Sulfree rig (Figure 4) should have been shipped to Crumb’s facilities at Dromiskin, Co. Louth and installed where it would undergo extensive trials in a real-world setting by all partners and will be fully optimised to consistently obtain low-sulphur pyrolysis oil (sulphur < 0.2% by mass) and activated carbon that meets the specifications (Hg capacity of 1.5mg/g 93% reduction of Hg in ratios of 9 mg S-AC/m3 flue gas).
However, the facility at Dromiskin, Co. Louth is being decommissioned hence it was not possible to install any new plant or equipment on this site, whereas the new facility at Drogheda, Co. Louth is being commissioned and although plant and equipment can be moved and installed from the original facility no new plant or equipment can be installed until the facility has been inspected and an operating licence has been issued by the council and Health and Safety officials.
The consortium partners therefore agreed to keep the Sulfree rig at the RTD performer’s site (HERI) where further optimisation took place and there was also the opportunity for any partners to visit to carry out further trials if they wished. The consortium believe that this has had no detrimental effect on the project.
The proof of concept for the Sulfree project has proved that this technology is now ready for progressing to the commercialisation of the process and during the project the following successes were achieved:
• Successful pyrolysis of rubber crumb using microwave technology
• One step “carbon black” production
• Modular design.
• Overall system designs for all sub-units to allow scale-up and installation at commercial end-user sites
• High efficiency process.
• Instant heating
• Internal reactor conveyance system
• Self-cleaning
• Stop/start – semi continuous
• Low odour (clean process), low tar production
• Fine carbon black particle size
• Production of “carbon black” and “low sulphur oil” with significant resale value to make the system commercially viable
• Identification of a suitable HDS catalyst to remove sulphur from pyrolysis oil
• Optimised HDS process for the recovery of sulphur-rich gas and low-sulphur oil
Potential Impact:
There are 4200 EU companies active in tyre and rubber activities, with an employment of 360,000 and total turnover €43bn per year. The recycling and waste treatment sector in the EU has a turnover of €227 billion, corresponding to 2.2% of EU GDP, including waste treatment (€52 billion) and recycling (€24 billion, over 500,000 jobs). The recycling sector includes over 60,000 companies, of which 97% are SMEs and the EU has one third of the world share of eco-industries and a 50% share of the world market in waste and recycling industries. The EU has a range of regulatory measures dealing with waste, a strategic approach to waste and resources, legislation regulating waste treatment and management of specific waste streams (end-of-life tyres, end-of-life vehicles, biowaste, electrical and electronic equipment). European legislation plays a strong role in driving development and markets. Current ELT recovery and recycling methods achieve very high recovery rates (96%) but do not address the resource efficiency challenge; neither do they recover the valuable materials from which a tyre is made of. The products of current ELT recycling methods are low value and no microwave pyrolysis ELT plants are in operation.
Regarding long-term economic viability, the partners have several options: the process plant can be sold “as is”, components of the process can be individually sold or the individual products (oil, sulphur, S-AC, steel) can be sold. The consortium SMEs have decided that given (a) the lack of commercialised operational microwave pyrolysis plants despite intense interest, (b) the very diverse and wide applications of oil, sulphur and steel, (c) the potential of using the SULFREE system for pyrolysis of organic waste, they will promote the SULFREE technology to tyre recycling and tyre manufacturing as a complete ELT recycling process with valuable output products; oil and sulphur are an important component of tyres and S-AC is essential for reducing mercury emissions.
Additionally, the patented Carbon Activation Chamber, Fixed-bed HDS Reactor, H2S removal unit and sulphur retrieval unit and the Heat Exchange System will be promoted to Chemical Processing SMEs, active recycling. It is worth noting that since the Fixed Bed Reactor and the H2S and sulphur removal unit will be on a much smaller scale than those used in the refining and petrochemical industry and these sectors will not be targeted. The tyre sector and chemical processing sector are the first tier markets.
Benefits at the European and international level are: increased competitiveness in global tyre recycling markets by improving recycling rate and quality of output and by employing a novel technology, strengthen the EU’s position as the leader in tyre recycling. Furthermore reduced mercury emissions and control cost, increased competitiveness of tyre industry by reclaiming materials and lessening reliance on imports, increased use of biomass derived biofuel. There is also significant market potential outside the EU. In the USA every year more than 4.6 million tonnes of
ELT are recovered for recycling and annual mercury emissions are 232 tonnes. Since 2005, the “Clean Air Act” (US Environmental Protection Agency) is in effect, which legislates that by 2018 coal fired plants will have a cap of 15 tonnes/year mercury emissions. The US’s annual estimated cost damage due to mercury emissions is $580 million. The successful development of SULFREE technology would significantly improve the competitive position of European technology. The benefits for SME manufacturers and suppliers are vast. Once a European capability is established, EU companies may be offered the opportunity to expand into the North American, Chinese and Asia/Pacific markets, by selling and licensing the technology into those markets. SULFREE contributes to several EU policies: EC Directive 1999/31 (ban landfilled tyres), End of Life Vehicle Directive 200/52/EC, European Mercury Strategy, Renewable Energy Directive 2009/28/EC,
Directive 2003/30/EC “On the promotion of the use of biofuels or other renew-able fuels for transport”.
To further illustrate benefits of SULFREE for the end user, a commercial review was undertaken that considers small and large scale processes and those found in literature, under certain assumptions. The review clearly shows the commercial viability and improved profitability of SULFREE. Existing pyrolysis processes have their potential restricted by the high sulphur content of the pyrolysis oils, which is a major limitation. Refineries will often not accept such high sulphur content oils or offer a substantially lower price in view of additional costs for sulphur removal.
The economic impact of SULFREE is considered for the 4 years after project completion. It is expected that the overall financial savings generated from the successful implementation of
SULFREE will offer increased business opportunities for the participating SMEs and the EU recycling, tyre and biomass industry. The potential savings provide a strong incentive to use the research and SME developed technology on an international basis.
The prototypes will be fully commercialised within 12 months of project completion and the SMEs will have direct economic benefits. The total project investment is approximately €1.5 million with an additional €0.5 million for commercialization after the project’s end. The economic impact is calculated for the 4 years after project completion, based on the benefits presented above and for: annual inflation rate 2.8%, gross profit margin 50% (high-tech), 1 new job position per €120k.
Initial results and economic assessments are indicating that the Sulfree project has 2 potential income streams. The pyrolysis unit developed by HERI and the steam activation unit developed by Mervilab can produced both steam activated carbon black (Income €4 per KG for medium quality and €7 per KG high quality) and sulphur rich unrefined oil (approx. $55 per barrel) the extra units (Claus and amine stripper) would only give extra income in the form of $80 per barrel for refined oil, however the additional costs for these 2 units have been shown to only be attractive to larger SMEs with the return on investment timescales too long for smaller industrial companies.
Dissemination
A project website was created for the Sulfree process and can be found at www.sulfree.eu
One scientific publication was produced: Casos de éxito: Mervilab; Infoactis; Issue 25 (Abril-May-June 2014)
Even though no project workshop has been organised for Sulfree, Autico and Crumb attended an event from EU LIFE project DEPOTEC, a thermal pyrolysis solution for waste tyres, in November 2015. There were good opportunities for networking as the event attracted over 60 delegates.
Three conferences were attended:
Ecomondo. November 2014 in Rimini, Italy plus a poster ‘The SULFREE process’.
ACHEMA. June 2015 in Frankfurt, Germany
AMPERE. September 2015 in Krakow, Poland
Apart from conferences and the workshop there has been no direct contact with interest groups
A video of the Sulfree process has been made and is available for viewing on the project website www.sulfree.eu
Exploitation
The proof of concept for the Sulfree project has proved that this technology is now ready for progressing to the commercialisation of the process and during the project the following successes were achieved:
• Successful pyrolysis of rubber crumb using microwave technology
• One step “carbon black” production
• Modular design.
• Overall system designs for all sub-units to allow scale-up and installation at commercial end-user sites
• High efficiency process.
• Instant heating
• Internal reactor conveyance system
• Self-cleaning
• Stop/start – semi continuous
• Low odour (clean process), low tar production
• Fine carbon black particle size
• Production of “carbon black” and “low sulphur oil” with significant resale value to make the system commercially viable
• Identification of a suitable HDS catalyst to remove sulphur from pyrolysis oil
• Optimised HDS process for the recovery of sulphur-rich gas and low-sulphur oil
All partners in the consortium agreed to share the IP allowing each partner to develop their own exploitation strategy. The exploitation agreement was discussed and finalised at the final project meeting in Drogheda, Co. Louth, Ireland on the 23/24th February. The agreement that has been signed by all the SME partners is as follows:
Background
At the final project meeting in Drogheda, Co. Louth, Ireland on the 23/24th February 2016 three different exploitation routes were discussed by the Consortium. These three are;
1. To maintain development momentum by some of the SMEs applying for a Horizon 2020 “Fast Track to Innovation” follow-on Project, 2 years in duration, min. of 3 countries, 5 partners max. Consortium needs to be Industrial and capable of launching on the market, directly or indirectly via say further licensing.
2. To Form a Joint Venture Company, to enable all the SME rights to be united in one Commercial vehicle. The JV would establish a detailed business plan and be able to license the developed technology or raise funds via VCs/Banks etc. to exploit.
3. To agree further to the Consortium Agreement Clauses detailing each SME partner’s Sulfree Earnt Rights, which each partner is free to exploit the entire Sulfree Technology / Process / Results for themselves, on a non-exclusive basis, but with full rights to sub-license to third parties.
Discussions
After lengthy discussions on the three routes to exploitation above, the SME partners present (Crumb Rubber Ireland, Autico Ltd, Fricke und Mallah Microwave Technology GMBH, Material Y Equipos De Vidrio De Laboratorio SA, Note; WLB not present) decided on balance to accept exploitation route 3, i.e.
To agree further to the Consortium Agreement Clauses detailing each SME partner’s Sulfree Earnt Rights, which each partner is free to exploit the entire Sulfree Technology / Process / Results for themselves, on a non-exclusive basis, but with full rights to sub-license to third parties.
WLB have been separately informed of these discussions by e-mail.
Agreement of Sulfree SMEs
Hence it is agreed further to the signed Sulfree Consortium Agreement by signature below that each SME Partner will transfer all of their Sulfree Earnt Rights, Sulfree Intellectual Property (IP) and Sulfree IP Rights (IPRs) into a ‘common pool’ to unite the ownership of the IP and IPRs, so that each SME partner can be granted from this a non-exclusive, perpetual, worldwide, royalty free licence to exploit the Sulfree Technology / Process / Results (from the FP7 Sulfree Project No. 605246) for themselves, on a non-exclusive basis, as they wish. This agreement does give any SME partner the right to transfer their licence to other 3rd parties. Furthermore, the perpetual duration of this license is dependent on the SME partner carrying out (and evidencing) reasonable efforts to exploit the Sulfree Technology / Process / Results during a period of 2 years after the project end date. If the SME partner does not make efforts to exploit then their licence will expire 2 years after the end date of the Sulfree EC FP7 Project (i.e. 29 Feb 2016 plus 2 years).
For the avoidance of doubt, any party undertaking further development (i.e. further to this license scope) of the Sulfree Technology will fully own solely all rights to such further developments.
This agreement has been signed by all the relevant partners.
List of Websites:
Website www.sulfree.eu
Consortium:
The UK Health & Environment Research Institute. (Coordinator)
Contact: Simon Fawcett
Email: s.fawcett@pertechnology.com
Autico Ltd
Contact: Kevin Poole
Email: kevin.poole@autico.co.uk
Crumb Rubber Ireland Ltd
Contact: Leo Kerley
Email: leo@crumbrubber.ie
Fricke und Mallah Microwave Technology GMBH
Contact: Brais Vila
Email: b.vila@microwaveheating.net
WLB LIMITED
Contact: Marianna Vari
Email: mvari@wlbltd.eu
Innora Proigmena Technologika Systimata Kai Ypiresies Anonymi Etaireia
Contact: Vasilis Papadimitriou
Email: papadimitriou@innora.gr
Azienda Speciale Innovhub - Stazioni Sperimentali Per L'Industria
Contact: Gabriela Migliavacca
Email: migliavacca@ssc.it
Material Y Equipos De Vidrio De Laboratorio SA
Contact: Andres Del Alamo
Email: andres@mervilab.com
