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Biomass heatpipe reformer (BIOHPR)

Deliverables

Gasification tests of cotton residues in a gasifier have been done in order to investigate the product gas composition and to select appropriate bed materials. The results obtained so far are very promising. The experiments have shown clearly that it is possible to obtain a high quality product gas from cotton residues. Two kinds of experiments were done, one with air and one with water steam. Both gasification applications have shown that the production of hydrogen rich gases is possible. Olivine proved a very good quality bed inventory for cotton residues gasification. No problems of ash sintering and agglomerations were observed at temperatures up to 900 degrees Celsius. So gasification of cotton residues can be appropriate for small-scale applications.
The Control and visualisation system as well as plant valves, controllers, transmitters… are manufactured out of standardized industrial control components. (For example SIEMENS SIMATIC….) This is a cost effective, market available and safe to operate solution. The visualisation system is PC based and connected to control system. Via modem/telephone or Internet a remote control and visualisation as well program modifications are possible.
The Biomass Heatpipe Reformer is a newly developed gasification system, which enables to produce medium calorific, hydrogen rich fuel gases from any biomass or waste. Its design focuses on small-scale combined heat and power systems (CHP-systems) with hot gas cleaning and microturbines. Hot gas cleaning is the simplest measure to solve the tar problem but it demands the application of microturbines or high temperature fuel cells. Hot gas cleaning will not only avoid the condensation of tars it will also allow to reduce the dimensions of any gasifier. Accepting higher tar concentrations allows reducing the height of the reactor and reduces the necessity for costly catalysts. The required heating values for microturbines and fuel cells are only achievable by means of allothermal gasification in fluidised bed gasifiers. The new concept – indirectly heating of a gasifier by means of high temperature heat pipes - improves the performance of allothermal gasifiers significantly and will therefore be a key technology basic for small-scale CHP systems with integrated gasification.
Feeding of any kind of feedstock into a kind of fluidised bed reactor usually requires especially at enhanced pressure levels - costly feeding systems with screw-feeders, lock hopper systems and security installations. They are usually not only costly but also fault-prone systems. The feeding System used for the BioHPR prototypes uses a very simple physical effect and allows feed fuel particles directly into the fluidised bed trough a simple gravity chute. The physical effect ensures that the particles enter the fluidised bed at the bottom level and allows even controlling the feeding rate. The system may be used with any fluidised bed gasification or combustion system.
The Biomass Heatpipe Reformer is a newly developed gasification system, which enables the production of medium calorific and hydrogen rich fuel gases from any biomass or waste. The potentials for the gasification are depending on competitive usage, on growth conditions, on harvesting conditions and on local distribution of usable ground. These facts differ from country to country. At the moment there is missing a satisfactory working gasification system in the market, especially for small-scale applications. A substantial potential for the gasification of biomass via BioHPR technology could be found. The transportation costs of the biomass is a critical factor to be considered. That’s why application at site, where the biomass comes up are most interesting. The BioHPR with an adapted size is a promising option for an integrated concept for decentralised energetic use of otherwise not usable materials for heat and power production. Different industrial segments that are of special interest for the BioHPR technology could be defined. It was also found, when the available literature data from fermentation and gasification processes was studied, that biomass with a high total organic content (TOC) is the most interesting input product for syngas production as compared to the alternative biogas production via fermentation. The data clearly show two regions, the biogas region and the gasification region. Materials that have more than 60%TOC seem to be better for gasification.
Aspects of the hot gas cleaning system for large-scale applications of the bioHPR reactor concept were investigated with the aim to outline the solution of this problem rather than provide a complete solution. Product gas contaminants and their concentrations limits prior to utilisation are discussed. Data form literature along data from BioHPR prototypes are presented. A short review of hot gas cleaning methods is presented for each contaminant category, specifically, for particles, alkalis, tars and acidic compounds. Exact thermodynamic calculations of the product gas composition and phase equilibrium are performed with proprietary process simulation software to identify the temperature window within which the cleaning should take place. The results can be used as a guideline for designing a large-scale gas cleaning system. The investigation indicates that to achieve alkali removal (<1ppmv) through hot gas filtration the product gas has to be cooled below 600°C. To avoid tar condensation temperatures must be kept above 200°C. Industrial gas turbine’s maximum fuel inlet temperature is set at 600°C. Thus, to investigate appropriate sorbents to hot remove the rest of the contaminants (H2S and COS, HCl, HCN and NH3), or to directly feed the product gas to the turbine, we should operate at temperatures from 600°C down to 200°C.
The biomass potential in the 10 newly elected countries (alphabetically: Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia) was quantified. Bulgaria, Romania, and Turkey were also included in the overview. The potential was estimated by terms of annual dry available quantities (tn/yr) and amounts of thermal energy (GWhth) that could annually be saved from conventional primary energy sources. The calculation methodology was described in detail, In the case of crops residues the term availability was introduced as the percentage of crop residue that can be utilized for electricity generation, considering other possible uses of these residues. Data collected for each country: - Location, - Population, - Climate, - Gross domestic product and use, - Electricity production and consumption; - Biomass energy potential in GWhth/year for each kind of resource; - Overall biomass energy potential. Most of the NAS countries could well replace part of the conventional sources with biofuels to produce about 10% of the electricity currently produced. Specifically to the BioHPR concept, and any other small-scale gasification technology, agricultural and forestry residues should be considered first. MSW fuelled applications require sorting and processing of wastes prior to energetic utilization and a far more complex gas cleaning integrated system that suits better to large-scale applications.
The equipment for filling and closing the heat pipes consists of: - Port ampulla device; - Ampulla breaking device; - Electric oven; - Heatpipe closing device; - Vacuum installation. The glass ampulla with the required sodium quantity is introduced in the port ampulla device. A manual device has the role to break the ampulla. The electric oven is used to heat the pipe to 850ºC.The closing device consists of a hydraulic vice. The jaws of the vice are connected to high current and low voltage, they have also a proximity sensor to open and close the circuit. The technology for filling heatpipes with sodium consists of the following main stages: - Insertion of the sodium ampulla; - Electric heating of the heatpipe; - Vacuum generation; - Heating of the port-ampulla device, until sodium melting occurs; - Breaking of the sodium ampulla; - Closing, cutting and welding of the filling edge. The technology and installation have been tested and used for manufacturing the sodium-filled heatpipes for prototype B of the biomass reformer. In this stage it involves mostly manual work, but it can be further improved, especially in the heating stages. Productivity can also be improved.
This report contains the basic engineering of the first possible applications of BIOHPR-CHP in Greece. Two major agricultural residues are considered for the biomass fuel of the application, namely cotton residues (for which BioHPR was originally intended) and olive husks. The proposed scheme focuses on the application of a CHP unit of 60kWel next to a centrifugal olive oil extraction unit. There are about 2,700 similar units in Greece. Other European countries with such units are Spain and Italy. In the proposed scheme part of the CHP’ s heat is used to partly evaporate and thus minimize the toxic and presently unsolved problem of the wastewater stream of centrifugal olive oil unit. The CHP scheme’ s planning is presented analytically together with detailed energy and mass balances. According to the capital cost estimation given by the coordinator (presently 3000Euros/kWe) the economics of such a venture are presented. Nevertheless the application of a CHP system that provides electricity, heat and minimizes the olive oil producing unit wastewater to be treated could make the difference. An integrated BioHPR-CHP with wastewater minimization could then appear an economic option.
As a result of the research work a hot gas filtration unit was constructed and built which is - Usable up to 350°C, - Usable for the filtration of tar containing gas, pyrolyse gas, - It is well cleanable with back flush gas stream, - It is constructed for the removal of high particle loads, - Well adjustable to the working conditions, to the appropriate gas. The laboratory scale unit is provided with Bekiflow HG type metal filter cartridges of NV Bekaert SA and uses Bekaert�s buck flush cleaning system. It is built for cleaning hot pyrolyse gas before the gas enters a mickroturbine - but it may be used at similar surcumstances as well.
The IKE experimental set-up for investigations of hydrogen diffusion through metal walls at high temperatures and under moderate pressures enables reliable measurements of the hydrogen diffusion rate. Due to the construction of the set-up systematic measurement campaigns under different experimental conditions with different test-specimen can be carried out generating a large data-basis, which can be statistically analysed. A special focus of the experiments is the influence of coatings, like plasma sprayed coatings on the hydrogen diffusion at high temperatures. Experimental results show that by means of thin wall coating ZrO2.Y2O3 the hydrogen diffusion is reduced compared to an untreated wall (reference material INCONEL 600). A further reduction of hydrogen diffusion is possible by means of oxidation.
Pyrolysis-gas can be burnt in the amended gas-turbine at continuous operation. Tar condensation problem can avoid with heated intake section, fittings and application with adequate discharging points. Fuel supply control system has to have high operation speed which fits to the gas-turbine operation. Only recuperated gas-turbine can be applied which gives enough high air temperature at fire chamber inlet, which is necessary for complete burning of very lean gas mixtures. Some modification at injectors can be necessary to resist to short flames, in order to avoid any damage and keep up operation for long term. Emission data can be kept in acceptable range. Gas turbine operation is sensitive for fuel pressure. For acceptable operation and controllability fuel has to have at least 1-2 bar higher inlet pressure over the fire chamber pressure value. As leaner the fuel-gas as higher pressure difference is needed.
The biomass potential in the newly associated countries is estimated in view of the BioHPR application market study context. The main energetic use of the solid biomass potential considered is electricity generation as this is the main purpose of BioHPR utility. The main aim is to illustrate the present and possibly economically achievable potential for the accession countries. The study includes the following main topics: - Heat production; - Co-generation of heat and power; - Bioethanol production; - Biodiesel production; - Charcoal production; - Costs of bioenergy utilisation; - Long-term development potential in Europe; - Main types of biomass resources; - Key advantages of biomass; - Applications of small scale biomass gasification; - Business opportunities in some of NAS countries.
The design of Prototype a heat pipe reformer has been developed to an extent that the manufacturing drawings could be derived directly by the manufacturer LFT. The objective of Prototype A was to validate the heat pipe reformer concept as such. The highly integrated version of the reformer with char filter included in the reformer has been developed as Prototype B mostly by LTK. As one of the leading developers of steam gasification processes for biomass and fossil fuels, we could contribute to the project with a wealth deal of experience with respect to process technology, pressurised reactors, materials suitable for high temperature environments with reducing atmosphere. Particular challenges were in the design of the passage of the heat pipes through the separating plate between atmospheric combustor and pressurised gasifier including the insulation of the separating plate against heat loss and the design of a steam cap system to allow the heat pipes to ventilate hydrogen that has come inside through diffusion. The profit for DMT is in keeping track of the development of biomass gasification on a basic scientific level and particularly the participation in the development of a biomass gasification technology with prospect of widespread decentralised application. By the end of June 2004, in the context of restructuring and getting closer to its roots of technical services in the field of coal mining, DMT has given up biomass-to-energy activities completely. The persons charged with biomass gasification inside DMT, belong to a small management buy-out company now.
A way to analyse the product gas, is to use the Raman Spectroscopy. The light source, which was used in this project, was a pulsed laser beam at the wavelength of 532nm. This method can be used in every gasification system and has the advantage that it is an on-line application. This enables to observe the quality of the gas and to fix parameters like the temperature of the gasifier or its pressure, so that the heating value of the product gas becomes as high as possible. Another very important signal that can be received with a Raman Spectroscopy set- up system is the strong fluorescence signal of the tars that are in the product gas. This on-line signal can help to reduce the tars in the gas and to optimise their content in it. The main advantage of this technology compared to commonly used measurement methods is the availability of on-line data of different species and the tar content, which can be measured simultaneously.

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