Final Report Summary - IRECE (INDUSTRIAL RECYCLING OF CFRP BY EMULSIFICATION)
Executive Summary:
Following the successful achievements of the Clean Sky Project SUSRAC, "Sustainable Recycling of Aircraft Composites", the IRECE project, "Industrial Recycling of CFRP by Emulsification", aimed at the development of a complete plan for the industrial production of thermoplastic highly filled composites based on Polystyrene matrix and CFRP dispersed phase, following the pilot scale demonstration.
The industrial plant has to be designed starting from the following concepts:
The carbon fibre reinforced resins (CFRP), either thermoplastic or thermosetting, are ground to different sizes and emulsified in a thermoplastic matrix in order to obtain sheets or granules. The emulsification process is carried out at room temperature (hence, cost effective) using as thermoplastic matrix Expanded Polystyrene (EPS). Such material is made widely available as result of its use as loose fill packaging for fragile goods. Moreover, its lightness (30 kg per cubic meter, on average) makes its disposal highly difficult. Combining these two streams of materials, namely CFRP and polymer matrix, the industrial process aims to obtain good performing composites and, at same time, low cost, and the industrial plant must reach these targets, but also a complete evaluation of the ecology and economy of the process.
The skills of the proponent and of the chosen partner guarantee a complete definition of all the industrial variables necessary to a complete estimation of costs and impact of the innovative production.
WPs/tasks vs. DoW in % of completion:
WP1 - Feasibility in the real industrial environment of CFRP milling and sorting It is completed at 100% in all his Tasks
WP2 - Feasibility of mixing and extruding CFRP in a thermoplastic matrix in a real industrial environment It is completed at 100% in all his Tasks
WP3 - Technical and economical impact of the selected industrial technology. It is completed at 100% in all his Tasks
WP4 - Environmental Impact and Risk Assessment of the Production cycle. It is completed at 100 % in all his Tasks
WP5 - Manufacturing plan for end item top assembly. It is completed at 100 % in all his Tasks
WP6 - Dissemination and Final Report. It is completed at 100 % in all his Tasks
WP7 - Management. It is completed at 100 % in all his Tasks
Main Resources used in the Project
Most of the resources of the Coordinator and of the Partner were employed for the activation of Research and Technical Assistance Contracts. Some resources were allocated for the participation to conferences on sustainable materials.
Project Context and Objectives:
Thermoset composite materials are used in a wide range of applications in industries such as automotive and construction. Continuous carbon fibres and epoxy resins are used for critical applications in the aerospace industry. In Europe, approximately 1 million tonnes of composites are manufactured each year. Although there are many successful uses for thermoset composite materials, recycling at the end of the life cycle is a more difficult issue. However, the perceived lack of recyclability is now increasingly important and seen as a key barrier to the development or even continued use of composite materials in some markets.
CFRP (carbon fiber reinforced thermosetting plastics), such as CF/Epoxy, has been used for aerospace fields as high strength, and light weight material. It is said the next stage of CFRP is wide spread use to many other general industrial field. Key points are the cost, the reduction of the energy consumption in manufacturing, and recycling.
Concern for the environment, both in terms of limiting the use of finite resources and the need to manage waste disposal, has led to increasing pressure to recycle materials at the end of their useful life. Where it is economically cost effective to recycle, materials recycling operations are already well established and driven by economics, for instance in the metals industries.
RECYCLING OF CFRP BY THERMOSET RESIN
The problems in recycling thermoset composites are as follows.
Thermosetting polymers are cross linked and cannot be remoulded, in contrast to thermoplastics which can easily be re-melted. Some thermosetting polymers can be converted relatively easily back to their original monomer, such as polyurethane. However, the more common thermosetting resins, such as polyester and epoxy are not practical to depolymerise to their original constituents.
Composites are by their very nature mixtures of different materials: polymer, fibrous reinforcement (glass or carbon fibre) and in many cases fillers (these may be cheap mineral powders to extend the resin or have some other function, such as fire retardants). There are few standard formulations and for most applications the type and proportion of resin, reinforcement and filler are tailored to the particular end use.
Composites are often manufactured in combination with other materials. For example there may be foam cores to reduce weight and cost or metal inserts to facilitate fastening onto other components.
In addition to these specific problems, there are the other problems associated with recycling any material from end of- life components, such as the need be able to deal with contamination and the difficulty of collecting, identifying, sorting and separating the scrap material.
A number of recycling technologies have been proposed and developed for thermoset composite materials. There are fundamentally two categories of process: those that involve mechanical comminution techniques to reduce the size of the scrap to produce recyclates; and those that use thermal processes to break the scrap down into materials and energy.
ICTP-CNR has recently developed a process for the preparation of recyclable thermoplastic composite materials with high fillers charge (60 % or above), constituted by an emulsion of recycled CFRP particles and polystyrene (PS) or ABS, tied up together thanks to a binder that guarantees the homogeneity on micro and macroscopic level and the attainment and the maintenance of the mechanical properties. It is important to underline that PS, as expanded Polystyrene (EPS) and ABS are both polymers highly present in the urban and industrial plastic wastes.
CFRP parts of end-of life aircrafts were used as CFRP waste, and the process has been proven on labscale and is being tested at pilot scale. The obtained mechanical properties, thanks to the peculiar process of emulsification, are in the range of engineering composites for structural applications (elastic modulus > 12 GPa, impact resistance > 13 KJ/m2).
Dimensional reduction of the composite was carried out by the proper grinding system, in order to get small particles. Then, the so obtained granules were mixed with fluidified polymer matrices, according to a proprietary process, aiming at producing a fluid composite containing at least 50% by weight of thermoset residue.
The obtained compounded granules can be pressed into solid plates with different thickness that find application in outdoor furnishing (tiles, flooring, etc.).
On the basis of the above achievements, the present project aims at the definition of all the steps needed to bring the process from pilot scale to a industrial phase, applying all the necessary methodologies, to those of virgin materials, but with lower cost.
WPs/tasks vs. DoW in % of completion:
WP1 is completed at 100 % in all his Tasks
WP2 is completed at 100% in all his Tasks
WP3 is completed at 100% in all his Tasks
WP4 is completed at 100 % in all his Tasks
WP5 is completed at 100 % in all his Tasks
WP6 is completed at 100 % in all his Tasks
WP7 is completed at 100 % in all his Tasks
Project Results:
The realised industrial plan allow:
• the definition of all the relevant technical, economical and environmental parameters. The industrial translation of a labscale research process involves a close relation between the group of researchers and the process engineers, in order to evaluate each single step of the innovative technology in their involvements not only technical, but also economic and environmental sustainability of choices.
• the focus on the creation of value in the context of a long-term vision. The industrial plan within the planning process, is the definition of strategies to maximize the creation of value. Often short term operational requirements do not allow companies to spend time analyzing the sectoral dynamics, the behavior of the competitors and the identification of good opportunities, the introduction and continuous improvement of the process of creating strategic, but instead contribute to create opportunities where you can develop innovative strategies that enable you to create and maintain competitive advantage. The sustainability of competitive advantage can certainly be favoured by the existence and quality of the process of drawing up business plans.
• the creation of a guide for the management of the business. The industrial plan, and more specifically the Action Plan - with the definition of the actions of the timing - is an instrument which controls the main modes of operation and in particular the entry into new markets, introducing new products and services The use of new distribution channels, the expansion of thecustomer base and the retrieval of all resources - financial, human, organizational and technological - necessary to implement the strategic objectives.
• the development of a useful learning process. The process of structuring the plan becomes a learning tool that allows you to check the quality of the possible strategies and thereby reduce the risks. In fact, the preparation of the industrial plan usually involves its progressive refinement and therefore the development of later versions in an iterative process: the assumptions are incorrect, the areas of weakness and inconsistencies are corrected so gradually, while the stimuli and insights arising from evaluation of early versions of the plan are incorporated, integrating and improving the original strategic plan. Drafting and critical review of the industrial plan are a way to be prepared to explain and defend their strategic choices in relation to the financial market in order to reduce the risk that they are not adequately understood, and for that fact alone, not approved.
WP1 Activity - Feasibility in the real industrial environment of CFRP milling and sorting
The present WP aims to show the main phases of the analysis carried out on the grinding/sorting process of composite materials made of carbon fibres; the target of the IRECE project is to consider the recovery and recycling of these materials in order to produce thermoplastic materials that will be used as secondary structures and accessories within aeronautic industry and/or other kind of products for other sector of manufacturing industry.
The IRECE project represent the natural prosecution of the SUSRAC project whose outcomes allowed the development of an experimental process in laboratory. It aims to detect all the solutions necessary to make the outcomes of the experimental phase applicable to the realization of an industrial process.
1. Technological analysis
The use of composite materials is characterized by undeniable advantages linked to their intrinsic features, such as:
• Lightness;
• Solidity;
• Fatigue resistance;
• Moulding.
These characteristics made the use of composites noteworthy in several industrial fields and especially in aeronautic industry.
The spread of these materials, though bearing countless technological advantages, presents problems connected with their disposal once worn-out.
Difficulties depend on economic expenses and on the considerable space amount needed in case of disposal in dump both of production scraps and of products and by-products resulting from dismantling and demolishing of the components realized with these materials. Therefore, it is of considerable economic and environmental importance the study and the development of industrial processes apt to use these “scraps” as raw material to realize secondary and non-structural components which would be re-employed in the aeronautic industry or in other possible sectors.
The process target of the present work involves these material as “fillers” used to create composite materials with a thermoplastic matrix in order to enable their subsequent pressing and/ or moulding to realize various auxiliary components.
The high mechanic resistance of the composite materials used as primary “filler” is the characteristic that makes more difficult the process of their reclamation and recycling. They need pre-processing finalized to grinding in order to make them usable as “filler” in the next transformation processes.
The mechanic characteristics of the material make the effects of the grinding process on the conformation of the rotors of the grinder and on its blades critical.
Analyses have been conducted in order to overcome the intrinsic difficulties of this process and to facilitate maintenance services. These analyses have been directed towards grinders with staggered edged knives in order to proceed, within the same device, with subsequent cuttings by a staggered step rotor; this way the process is split in several phases performed within the same device. In fact, the eccentric assembling of the blades allows a pre-reduction of the size of the inserted materials.
On the basis of the previous preliminary directions the choice of the type of grinding devices fell on grinders with a rotor with sectored blades and not with a single blade.
The main advantage of this kind of devices consists in the arrangement of the “knives” on the rotor, which produces a gradual impact of the sectors on the counter-blades (not a single impact rotating blade – counter blade) therefore, the production being equal, the electricity consumption results even 50% less than grinders with continue rotating blades.
The typology of rotating blades belongs to the type with constant profile, therefore after the tool grinding they do not need to be regulated on the diameter, but they can be set in their housing and locked with bolts and a torque wrench. This contributes to a considerable reduction of maintenance expenses.
Rotating blades are placed to create an helix which channels the product to grind inwards during the rotation; this allows the grindings alongside the whole rotor length.
The monitoring system of the blades allows to obtain an high flexibility in the setting of the milling process; in fact, the different kinds of blades, varying in their hardness degree, permit quick adjustments depending on the specific features of the materials actually treated. In the specific case of “carbon-fibre reinforced plastic with high Tg thermoplastic matrix or thermosetting matrix” is suggested the use of highly flexible blades in order to avoid their rapid consumption and lower maintenance expenses, increasing their actual service life.
Rotating blades will be spread on the rotor so to constantly channel the product towards the centre of the device, saving this way even the sides of the device itself, which appears still intact even after many years of work.
2. Devices research
On the basis of the data stated in the previous paragraphs, in light of the information obtained by the development phases of the SUSRAC project, it has been set going the recognition of possible suppliers of devices already operating on the market and applicable to the present project, not recurring to the realization of dedicated devices. Marketing researches led to the individuation of at least three possible producers of “grinding lines” with suitable features.
The producers will not be identified by name, they are all Italian owned companies, and are:
• Producer 1;
• Producer 2;
• Producer 3.
On the basis of the information given (grinding material features, time capacity…) only two
producers have made an offer and have supplied characteristics:
• Producer 2;
• Producer 3.
Both producers have identified as devices suiting the process requirements a grinding line able to work, for the specific material treated, within a range of 1.000÷1.500 kg/h, whilst only the Producer 3 proposed also a line able to work within a range of 4.000÷5.000 kg/h.
The products proposed are based on different technologies:
• Producer 2 proposed a “two-stage” system;
• Producer 3 proposed a “one-stage” system.
Depending on the two different technologies proposed (“two-stage” and “one-stage”) it is not proper to realize a detailed compared analysis of the two line types proposed; nevertheless it is possible to compare their energy requirements on the basis of the set up electric power.
Considering the offers and the technical files attached, it follows that the set up electric powers in the analysed cases are:
• “Two-stage” line = 150 kW;
• “One-stage” line = 132 kW;
involving a clear advantage of the “one-stage” line in terms of energy engaged on the whole during a type year of the working plant.
3. Solution proposed
The preliminary energetic analyses carried out in the previous paragraphs suggest that the best solution to take, on the basis of the information and features supplied by some producers of grinding lines, is the implementation of n. 5 grinding lines with a maximum potential of 5 t/h.
This solution has undeniable advantages, not only concerning energy:
• The reduction of the obstacles on map both for “one-stage” and even more “two-stage” solution;
• Margin of extra productive capacity of about 2.250 kg/h that, projected over the whole yearly
productive cycle, allows to treat up to 33.000 t/year with a margin of the 10% compared to the initial datum of the project and without any other investments.
Considering the possible powder emission in the environment, mills will be installed in a soundproof cabin each constantly kept in depression by a system of powder demolition connected also to the grinding chambers.
Likewise the power supply chambers will be connected to the network of the dust removal systems in order to avoid any powder leakage.
WP2 - Feasibility of mixing and extruding CFRP in a thermoplastic matrix in a real industrial environment
1 - Process Data
According to the SUSRAC project that represents the origin of the present work, the transformation and re-use process of CFRP coming from aircraft dismantling, production scraps and/or other industrial sources, is based on the creation of a gel solution of EPS and emulsifier. In this solution powders and/or ground parts of CFRP are dispersed in order to produce a mixture composed, in its final configuration, by the 70% by wt of CFRP and the 30% of EPS.
This relation represents the characterization of the product; nevertheless other mixtures are possible, for instance the one with 60% of CFRP and 40% of EPS. It is evident that, reducing the CFRP percentages, the mechanical characteristics of the finished product decrease; for this reason the mixture composed by the 70% of CFRP and 30% of EPS has been chosen as the reference for the design of the plant. In this way the greatest mechanical characteristics are guaranteed for the final product.
The process consists in the solubilization of EPS in emulsifier to create a gel where it is possible to disperse the recycled fibers coming from the grinding process discussed in the WP1.
In order to reach the complete dissolution of EPS, the mixing ratio Emulsifier/EPS is assumed equal to 1.5 in the present work.
2 - Pre-design of the production cycle
The production cycle of a whole day has to be designed to handle 37.500 kg/day of CFRP coming from the grinding plant; this value has been chosen to respect the hypothesis of annual production mentioned in the previous paragraph.
Considering the following mixing ratios:
• EPS = 30% by weight of the output;
• CFRP = 70% by weight of the output;
along with the weight ratio emulsifier/EPS necessary to the formation of the gel, it is possible to proceed to the determination of the volumes needed for one work shift in the hypothesis already mentioned.
The CFRP to handle in a whole work shift is equal to 37500 kg, then the required amount of EPS is 16100 kg; for the dissolution of such a quantity of EPS, almost 24150 kg of emulsifier are necessary.
3 - Mixing system
Since the masses and the densities necessary to the process development are known, it is possible to evaluate the volumes of the materials involved in the process:
• CFRP = 37500/1500 = 25 mc;
• EPS (apparent volume) = 16100/30 = 540 mc;
• EPS (volume in dissolution) = 16100/1050 = 16 mc;
• Emulsifier = 24150/740 = 33 mc.
Since the difference between the EPS volumes (before and after the solubilization) is remarkable, the loading sequence of the reactor consists in the immersion of the whole quantity of emulsifier, followed by the introduction of EPS.
In this way EPS contributes with its intrinsic volume to the formation of the gel, decreasing
considerably the volume of the mixer.
On the basis of the data already reported, it is possible to determine the theoretical reaction volume that is 75 mc.
Considering the necessity of disposing of volumes capable of allowing future improvements, increasing the general reliability of the system and assuring a suitable agitation of the product in the mixing phase, it is considered worthwhile to divide the total quantity in n.3 reactors with a single minimum capacity of 30 mc, for a total of 90 mc.
The reactors are made of stainless steel (AISI 304) with an inner multi-blade agitator (rotors distributed on four levels at least) made of the same material. In the spaces not occupied by the helixes, fixed counter-blades are arranged (installed on the reactor plating) to create a counter-rotating action opposed to the one of the main blades. This action guarantees a total and fast mixing of the materials.
4 - Storage and supply of emulsifier
The emulsifier can be of two types: virgin, coming from the outwards, or recycled, coming from the further production phases. In both cases, the emulsifier is stored in specific tanks outside the plant. In order to guarantee correct conditions of security and conservation of emulsifier, the storage tanks are kept in overpressure by flushing with inert gas (typically nitrogen).
The transfer of the emulsifier from the storage tanks to the mixers is guaranteed by process pumps with the body in stainless steel certified ATEX. These pumps are installed outside near the storage tank area.
For the design of the storage tank area, the following hypothesis are considered:
• Recovery in the phases of mechanical pressing = 65÷70%;
• Recovery in the phase of drying in oven = 30 ÷ 25%; the process losses and/or portions of emulsifier not recoverable are within the range 5 ÷ 10%.
In a conservative hypothesis of recovery and re-use of emulsifier equal to the 90% of the required total quantity, it is possible to evaluate the amount to replenish for each production week. In light of the above mentioned assumptions, the total weekly emulsifier requirement is 165 mc/week. To guarantee this requirement, it is necessary to arrange a weekly integration of 16.5 mc in addition to the 33 mc needed for the normal operation of the production cycle.
Therefore it is required to have a total emulsifier reserve of 33 + 16.5 = 49.5 mc.
It is proposed the realization of a tank park with an overall capacity of 70 mc, able to assure the correct implementation of the production cycle for n. 2 weeks. The storage tanks of the recovered emulsifier represent the first supply source of the reactors whereas the tank of virgin emulsifier is the second source to be used only when the quantity of recycled emulsifier is finished.
The flow rate of the pumps must allow the filling of each reactor (about 11 mc) in a maximum time of 30’; hence the nominal flow rate of each pump is equal to 25 mc/h with an approximate hydraulic head of 3 bar. The transfer lines made of stainless steel (AISI 304) are realized with drawn pipes welded together. Only the couplings with the process equipment (pumps, tanks, reactors, …) are realized with flanged systems.
The replenishment of the three mixers is executed in sequence in order to reduce the instantaneous flow rate of the pumps and the filling time of each mixer; in this way it is decreased the time of the whole cycle. Furthermore, the possibility of a differential filling of the three mixers allows to reduce the starting time of the plants, from the beginning of the work shifts.
5 - Storage and supply of EPS
The correct and complete execution of the process requires a daily amount of EPS of about 16100 kg.
In order to assure a functional autonomy for n. 1 week, the storage of such material is of 80500 kg and, since the EPS apparent density is 30 kg/mc, it corresponds to a minimum storage volume of about 2700 mc of EPS.
Considering the significant dimension of the storage of this material, it is assumed the realization of a dedicated rectangular shaped warehouse with a surface of 2000 m2 where it is possible to store about 160,000 kg of EPS sufficient to guarantee the production for 2 weeks. At one end of the warehouse (the one towards the production plant), it is planned the realization of an underground loading hopper from which the pneumatic transfer system for the convoy of the EPS to the mixers originates.
The pneumatic transfer system is of mixed type: in depression in the aspiration phase from the loading hopper, and in pressure during the unloading of the material in the loading hopper of the mixer. That solution allows two actions: the containment of the aspiration of EPS volatiles from the mixer when the slide valve (located at the unloading nozzle of the cyclone separator of the EPS); the reduction of possible problems of generation of bridges in same phase.
The parts of the pneumatic transfer system, that are in contact with the product, are made of stainless steel AISI304.
The single piping lines and all the other parts installed on them to form the whole pneumatic transfer system, are interlinked guaranteeing the electrical continuity and they are connected to the ground in order to avoid the accumulation of electrostatic charges and also the dispersion to the ground of possible failure currents.
NOTE: the necessity of storage and supply of the EPS may be eliminated in the hypothesis of a sampling and emulsification of the EPS realized directly near the accumulation areas of the packaging scraps, through a mobile or fixed platform. In this way, the gel of EPS/emulsifier arrives directly to the realization plant of the compounds, ready to be mixed with the CFRP fillers.
Storage and supply of CFRP
After the grinding process illustrated in the WP1, the CFRP is conveyed to a storage system composed by vertical silos.
Since the theoretical capacity of each grinding line is 5000 kg/h and considering that the plant functionality should be guaranteed for two consecutive weeks, the storage capacity must be 375000 kg of CFRP. As a consequence the necessary storage volume is equal to 250 mc.
That total quantity is divided in n.3 silos, each of them with a capacity of about 90 mc in order to have a free space at the top that compensates the irregular distribution of the material in the filling phase.
The partition of the material in n.3 silos allows the realization of devices with moderate dimensions (ø = 3.0 m; h » 13.0 m).
The type of pneumatic transfer considered for the CFRP is the same used for the transport of EPS; the only variation is the introduction of regulations about the radii of curvature to use in the changes of direction of the transfer lines, taking account of the particular mechanical characteristics of the carried material.
Pneumatic transfer systems
The pneumatic transfer systems considered for the handling of both CFRP and EPS are conveyed to dedicated mechanical filtration systems with bag and cartridge filters for the mechanical separation of the possible suspended particles not removed by the cyclonic systems at the service of the plants.
Following the mechanical separation systems, appropriate hydraulic seals and active carbon filters are planned for the total separation of the emulsifier particles airborne in the currents. In the same way, systems of hydraulic seals and active carbon filters are considered for the air valves of the main storage tanks and of the mixers.
Production of semi-finished panels
After the supplying and mixing systems previously illustrated, the process involves the casting phase of the “filled gel” and the subsequent production of the panels that form the intermediate semi-finished product.
The production stage of the semi-finished panels is characterized by the following elementary phases:
• Dosage and casting of the “filled gel”;
• Mechanical compaction of the “filled gel” to form sheets with a narrow quantity of emulsifier;
• Stripping of the remains of emulsifier in order to form the “dry” semi-finished panel to forward to the next stage of thermoplastic formation.
It is called attention to some similarities between the production process of the semi-finished panel in EPS+CFRP and the production cycle of the paper. In fact, the “filled gel” presents, for its workability, characteristics similar to the ones of the paper. For the latter the consolidated processes involve the separation by pressing the water in which the cellulose fibers and other additives are dispersed. Instead for the EPS+CFRP the removal of emulsifier always occurs by mechanical means.
Dosage and casting of the “filled gel”
At the end of the mixing process the casting and formation phase of the semi-finished panel starts. This stage begins with the opening of the slide valve of the mixer. The transfer of the “filled gel” is conducted by a gear pump. The choice of this type of pump depends on its specific functional
characteristic that guarantees the constancy of the volumetric flow rate on varying the rpm. In fact, the volumetric flow rate is not influenced by the pressure drops of the casting circuit and also by the hydraulic head of the mixer, the density and viscosity of the obtained mixture, etc. In this way, it is possible to modify the thickness of the panel simply operating on the rotational speed of the gear pump, leaving unchanged all the other operation parameters of the production line.
The casting of the gel occurs on a metallic conveyor belt through a linear system composed by a calibrated and adjustable opening.
The “filled gel” is casted on the conveyor belt with a thickness in a range of 0.5-1.0 cm.
Mechanical compaction of the “filled gel”
After the casting station discussed in the previous paragraph, counter-rotating rollers are installed in the upper part of specific rollers of the transfer system, with distances decreasing gradually, with the function of pressers/compactors.
At that stage almost the 70% of the initial amount of emulsifier in the “filled gel” is removed by mechanical means. This phase typically involves a volume reduction within the 30% and 35% with the consequent separation of the 60÷70% of the total contained emulsifier. The removed emulsifier is recovered in dedicated basins collocated under the mechanical compaction stations in order to be later re-conveyed in the main storage tanks allowing its re-use in the next phases of the production process.
The recycling cycle of the emulsifier is considered continuous, then the volume of the recovering basins is about 3 mc with the only aim to assure a correct management of the pouring phases through pumping systems characterized by appropriate transfer times, without requesting the continuous working of the transfer pumps.
Removal of residual emulsifier
Following the process of the mechanical extraction of emulsifier, it is necessary to guarantee the total removal of the residual emulsifier from the semi-finished product in order to allow the achievement of the mechanical characteristics required for the further re-use.
The removal of residual emulsifier may be implemented by taking advantage of two characteristics of this solvent:
• High solubility in water;
• Volatility concurrent with the low boiling point.
The two processes are essentially different and are illustrated below.
Stripping of emulsifier in water
Regarding this process, some tests have been carried out to evaluate the transfer kinetics of emulsifier to water.
The tests executed on laboratory samples have underlined that the release time of emulsifier in water, in order to guarantee the almost total removal, is of about 24 h.
In the hypothesis of the considered production process , the volume of the whole material to handle for each working shift is about 15 mc divided in the following way:
• CFRP = 25 mc;
• EPS = 16 mc;
• Emulsifier = 10 mc.
In order to assure an appropriate contact surface, it is assumed that between the several layers of semi-finished product a free space of 2 cm is left to allow a correct water flow. Under the hypothesis of semi-finished panels with a thickness of 0.5 cm after the process of “mechanical compaction of the filled gel”, it is necessary to have a total volume of water equal to 200 mc and containment basins with a net useful capacity of 251 mc at least. For a more flexible process, it is planned the realization of n.3 stripping basins of emulsifier, each of them with a volume of 150 mc. The presence of the third basin is essential to guarantee the load in the unloading phase of the first busy basin.
Furthermore, that basin functions also as a buffer tank in case it is necessary to increase the permanence time of the semi-finished product in water in order to maximize the stripping of the emulsifier.
It must be highlighted that such a process involves the need of proceeding to a treatment of distillation of the water used to separate the emulsifier, which cannot enter in the environment once dissolved in water.
From laboratory tests carried out to estimate the transfer kinetics of emulsifier to water, it may be noticed that, despite the previous mechanical elimination, the total removal is achievable with a permanence time of about 24 h, confirming that the necessity of at least n.3 basins is fully justified to guarantee the continuity of the production cycle.
The exam of the results related to the transfer kinetics of emulsifier to water shows the need to consider a following drying stage in a ventilated oven at 80°C in order to assure both the removal of the residual emulsifier and the drying of the water possibly absorbed during the period of immersion in water.
From the study of the transfer kinetics of emulsifier in a convention oven at 80°C, it is possible to observe that the complete elimination of the water occurs in 1 hour time in case of the absence of the immersion cycle in water. Assuming a total cycle time (product loading, warming, drying/evaporation, cooling, product unloading) of about 2h, it is planned the installation of n.2 convection ovens with a capacity of about 10mc. In this way, it is possible to dispose the loading with an interval of 1h. This solution corresponds to a saturation at the 100% of the production capacity of the ovens, then the installation of a third oven is considered to assure a suitable reserve in order to guarantee the correct working also during ordinary and/or extra maintenance of one of the ovens.
Stripping of emulsifier in oven
Following the results of the tests executed for the evaluation of the elimination kinetics of emulsifier with hot process in a ventilated oven, it is observed that the total elimination time of the solvent is below 1h from the reaching of the temperature of 80°C inside the cell.
This result suggests the utilization, as an alternative to the cycle previously illustrated, of a cycle that completely eliminates the stripping phase of emulsifier in water, opting for the direct insertion in oven of the semi-finished product after the mechanical removal of emulsifier through calendaring.
Even in this case, the results of the laboratory tests confirm that the total removal of the residual emulsifier is achieved in about 1 hour. Considering a cycle time (product loading, pre-warming, extraction time, cooling, product unloading) of about 3h, the oven system may be replaced by n.2 ovens with a single capacity of 15 mc able to satisfy the 100% of the production capacity of the mixing systems and of the casting and mechanical calendering line of the semi-finished product.
Recovery of emulsifier from the drain
Whether considering the stripping of emulsifier in water or in oven, there are problems in the recovery of the emulsifier removed from the product. In the case of removal in water, it is necessary to proceed to the recovery through distillation, then it is essential to consider appropriate storage areas and a process to execute outside the production plant. Instead in the other case, in order to recycle the emulsifier contained in the exhaust air from the convention ovens, it is possible to realize in situ a recovery system based on an exchanger-chiller supplied on the primary circuit by chilled water at high temperature (about 15°C).
WP3 - Technical and economical impact of the selected industrial technology
The present Workpage aims to evaluate the technical and economical impact of the pre industrialisation of the recycling process of composites made of CFRP (carbon fiber reinforced polymer). There will be individuated the minimum conditions to obtain a process that is economically competitive. From a preliminary market survey, the resulting reference scenario points out the absence of suitable plants for the treatment of fuselages and other aircrafts waste. As a consequence, the companies that own aircrafts have the economical disadvantage of incurring expenses to dispose the scraps as special waste. Furthermore the disposal operations are in contrast with the national and EU waste legislation which prefers the reuse and/or the recycling of scraps.
In particular there will be analysed the costs to bear for the realisation of the industrial line and the costs and the availability of waste to treat, eventually determining a profit and loss account.
Availability and costs of disposal
The project factor used in the design of the plant is based on an a maximum annual availability of recycled CFRP equal to 30,000 ton/year, then the annual production capacity of the grinding phase is 6,000 ton/year (daily capacity of 37.5 ton/year, process efficiency equal to 80% for 220 days/year). The existing market survey allows to determine that the disposal of dismantled aircrafts costs about 200 €/ton for it is necessary to commit it to companies specialized in the treatment of special waste. Since the energy content of such materials is low (for the high amount of incombustible carbon fiber), in the current scenario the most probable destination for this material is the landfill.
Consideration and assumption for the logistic and location of the plant In order to individuate the most suitable areas for the location of the plant, it is necessary to examine the geographical sites of the needed waste matters (CFRP,EPS). In fact, one of the essential factor for the cheapness of the production chain is an economically convenient supply of CFRP and EPS.
At this proposal, Italy was assumed as the country for the logistic and location of the plant considerations.
In particular in the south of Italy, the greatest available amounts of waste CFRP are located in the fuselage production area that is Grottaglie (TA). A second supply area is Pomigliano d’Arco (NA) where is available a smaller percentage of waste CFRP coming from the Alenia Aermacchi factories.
Concerning the EPS to recover, the supply is possible through the provision of scraps of EPS, free of contaminations and/or residuals, coming from other production chains ( i.e. appliances, building, etc….). In this case the raw material is available in a wider and more distributed geographical area, although it is possible to pinpoint some areas with a greater concentration of EPS: the big commercial areas and the industrial zones where there is the production of appliances and electronic components.
Considering the specific weight of the materials to recover (CFRP and EPS) and their location areas, it is essential to locate the plant near the EPS supply areas in order to obtain an efficient and economically convenient supply chain management. In fact the EPS has a substantial transfer cost because it is very light, whereas the transfer of CFRP is less onerous thanks to its high density.
In the present case, since the daily use of EPS is 16.1 ton/day, it is necessary the recovery of large amounts of EPS (about 3,220 ton/year). Therefore the decrease of the EPS supply costs is essential.
For the above mentioned reasons, one suitable location of the recycling plant could be the Caserta area where there are several and big shopping centres and an important industrial production area.
Analysis of the costs of the plant
The plant is composed by the following equipment:
• Grinders;
• CFRP storage silos;
• Warehouse of 2000 m2 for the storage of EPS and the housing oh the production line;
• Emulsifier storage tanks;
• Mixing reactors;
• Transfer systems;
• Mechanical pressing system with recovery of emulsifier (about 70%);
• Stripping system with ventilated ovens and condensation of the emulsifier (25%).
Analysis of the operating costs
The main operating costs related to the working of the treatment plant are divided in the following way:
• Personnel costs
For the running of the recycling plant, n. 10 employees are needed with the tasks listed below:
## N. 1 Chief of Production Department, holding a degree in engineering to employ “full time” for an annual gross cost of 50,000 €/year.
## N. 2 Process Technicians, graduated from industrial technical institutes specialised in chemistry or mechanics, with a “full time” contract. A technician is employed in the control room, the other one on the production lines. The annual gross cost for each technician is equal to 35,000 €/year.
## N. 2 Workers for the loading of raw materials and the unloading of packed products at the end of the process. The contract is “full time” and the annual gross cost for each worker is 26,000 €/year.
## N. 2 Workers for the grinding phase of the CFRP, to employ “full time”. The annual gross cost for each worker is 26,000 €/year.
## N. 3 Workers for the mixing phase and the stripping of emulsifier, to employ “full time”. The annual gross cost for each worker is 26,000 €/year.
The total gross personnel cost is about 302,000 €/year.
• Costs of the materials used in the production cycle
The input materials of the plant are: emulsifier, expanded polystyrene (EPS) and CFRP.
• Management, maintenance and financial costs
An item, regarding the costs of maintenance and consumables, is considered in the operating costs. It is evaluated in percentage regarding the cost of the plant.
The item contains:
- Ordinary and extra maintenance service carried by external personnel;
- Cost of the moving of goods linked to the logistic in entrance and exit;
- Small equipments for the warehouse and the workshop.
The operating costs only consider the industrial costs; in fact the following costs are not taken into account:
the general expenses, the accounting and administrative costs, possible costs due to the management of the considered business area.
Concerning the financial costs, a coverage of the financial requirement has been hypothesized. The financial requirement is related to both the fixed capital and the working one for the year 0, necessary for the realisation and the finalizing of the plant.
Evaluation of the investment payback
Nowadays, the sale price of the product on the market is equal to 4 €/kg but, if the production of recycled
CFRP increases, this price will decrease. For this reason three hypotheses about the market price are contemplated:
- Worst: sale price 0.5 €/kg;
- Medium: sale price 1.00 €/kg;
- Best: sale price 2.00 €/kg.
The cash flows, reported in the above mentioned attachments, have been discounted at a WACC equal to the supposed financial cost, that is 4.50%.
In conclusion, in the worst hypothesis the payback period is about 4.5 years whereas in the medium and best cases is lower than 3 years.
WP4 - Environmental Impact and Risk Assessment of the Production cycle
The Workpage aims to evaluate the general environmental impact of the productive process under consideration. In particular, the environmental impact of the final product and the impact related to the settled working activity will be verified. This approach has the purpose to confirm that the process is coherent with the objectives of respect of the environment , not only in terms of the current relevant regulations but mainly referring to the environmental benefits of the whole process. The environmental analysis will allow to proceed with the evaluation of the risks of the productive process, from an economical and environmental point of view.
The analysis is composed by a systematic diagnosis that studies deeply all the relations between the productive activities of the process and the environmental and territorial reality that surrounds it.
Thank to this analysis, it is possible to reach an overall evaluation of the environmental problems connected to the activity. Therefore it represents the starting point for the identification of the objectives and the procedures to be implemented by the company.
The environmental analysis must pinpoint:
- The direct and indirect aspects ( environmental aspect: element of an activity, product or service of an organization that can interact with the environment);
- The significant impacts (environmental impact: any alteration of the environment, negative or good, total or partial, resulting from an activity, product or service of an organization).
It is composed by the following actions:
- Identification of the environmental regulations applicable to the activities conducted in a company, for the compliance check regarding prescriptions and authorizations;
- Identification of the most significant impacts on which it is necessary to focus the targets of improvement and the evaluation of the size of the environmental impacts on the territory.
In addition, the analysis also includes the examination of all the procedures and practices that will involve the company in the environmental field and the evaluation of the analysis of the environmental incidents that can happen.
Methodological approach
The environmental analysis is divided in n. 4 stages:
• STAGE 1 – General analysis: the information concerning the production site, the type of business in question and the sector environmental regulations, is gathered;
• STAGE 2 – Identification of the environmental subjects: the environmental aspects in question are identified and analysed along with their compliance with the conducted working activity and the regulations;
• STAGE 3 – Evaluation of the environmental subjects: analysis of the impact that the environmental aspects of the process have in relation to the operators and the territory where the company works.
• STAGE 4 – Conclusions: a classification of the analysed environmental aspects is carried out identifying the reference environmental indicators necessary to pursue the expected objectives of protection.
CONCLUSIONS
For each process activity, the environmental aspects in the different operating conditions have been identified. Now, for each environmental aspect, the significance of the environmental impacts is evaluated with the criteria illustrated below:
• Classification of the impacts on the process:
- Low = 1 point
- Medium = 3 points
- High = 5 points
• Significance index of the activity:
- Low < = 15 points
- 15 points < Medium < = 20 points
- High > 20 points
Risk Assessment
As defined by the current regulations about the occupational safety (Directive 99/92/CE, for Italy D. Lgs. 81/08), the aim of the risk assessment is to organise all the necessary measures for the protection of the safety and the health of the workers. Its main tasks are:
1. Identifying all the sources of danger and evaluating their possible effect on the workers;
2. Removing or at least reducing the risk factors;
3. In case of non eradicable risks, providing suitable personal protective equipment to the exposed workers;
4. Planning and realizing the necessary information and training courses about the risks;
5. Organising all the activities needed to be in compliance with the regulations.
In the present report, the measures necessary to assure the best safety conditions are analysed in relation to the characteristics of the production line for the recycling of CFRP and EPS.
The measure will be identified considering the following sections:
a) Identification of the general, specific and emergency measures of protection;
b) List of risk factors and results of the risk forecasting;
c) Improvement factors of the levels of protection during time.
- Identification of the general, specific and emergency measures of protection
In this section the following aspects are analysed: the working place, the tasks of the workers and the used equipments. The objective is to identify the measures to implement in order to prevent and reduce the risks connected to the working conditions that can cause cross dangers, not placed inside a group of specific risks.
Considering the characteristics of the process in question, the general measures to implement are:
1. Correct information and training of the workers about the possible risks that can affect them. There will be organised theoretical-practical courses that explain the right conditions of use of the equipments and the materials involved in the process;
2. Arrangement of an appropriate system of management of the tasks in the different production phases, in order to restrict the possible exposure at risk factors;
3. Correct training about how to use the personal protective equipments (PPE) and identification of a team that manage emergencies and medical aid.
The specific measures are related to the particular criticality of rooms, machines, equipments and or/systems.
- List of risk factors and results of the risk forecasting
The criteria of analysis and evaluation are ground on the objective analysis of the criticalities found by evaluating the actual probability of occurrence of an injury, or of a damage to the health and safety of the workers. This probability is related to the seriousness caused by the damage due to the occurring of the event. The scale of the probabilities of occurrence of a dangerous event and its relative damage have the same quantitative definition, in order to make homogeneous the evaluation of the risk factor.
Then, it is necessary to evaluate possible criticalities of equipments, plants, structures and every factor that can represent a source of danger.
For the assignation of the values of the probability of occurrence of a dangerous event and of its consequent damage, the following sources have been consulted: data already present and relative to the used materials and equipments; technical rules, models, current regulations.
The risks have been divided into three groups:
• CROSS AND ORGANISATIONAL RISKS: they come from the criticalities related to the organisation of the tasks, working shifts, the treadmill of the tasks with repeated mechanical actions; criticalities due to the difference of category.
• SAFETY RISKS: all the risks that can compromise the safety of workers during the execution of their tasks. Among them, the following risks are classified: fire, flood, earthquakes, machines that expose to risks of trauma, cut or general injuries, explosions, plants, work equipment.
• HEALTH RISKS: in this category there are the risks connected to the exposure at chemical and/or physical (noise, vibrations, E.M. fields, etc…), or to the healthiness of rooms, sanitary conditions, microclimate and in general all the factors that can compromise the health of workers in case of extended exposure to the above mentioned agents.
During the phase of analysis and evaluation, the exposure of single workers (belonging to the same homogeneous area) to the above listed risks have been considered; the origin of potential risks has been identified, the opportune measures of prevention and protection have been listed along with the necessary means of individual protection.
- Identification of sources of danger and risks factors
In this phase the tasks of the single workers are identified, dividing them in homogeneous areas.
An homogeneous area is the set of activities associated for similarity of situations or tasks (competence, operational tools, environmental characteristics), and for which the exposure of workers to safety, health and cross risks are ascribable to similar factors.
Technical-economical risks related to the technology involved in the process
In addition to the risks concerning the health of the workers and the protection of the environment, another analysis is considered. Starting from the results of the deliverable D3.1 (Technical and economical impact) the analysis identify, and sometimes assess, the possible technical-economical risks connected to the technologies used in the process.
In fact, some potential technological risks were already identified in the preliminary study phases of the process. Some specific “emergency plans” should be considered for each risks.
These technological risks concerns:
- The storage and securing of CFRP;
- The mixing and pressing of the mixture CFRP+EPS+Emulsifier.
As already seen, it is possible to buy and use all the machines and equipments necessary to the phases of the process, starting from the existing technologies already used in other industrial fields (i.e. chemistry, building materials, plastic components etc…).
Then, no extra-costs have been noticed and the economical risks for the realisation and use of the production line can be considered minimal.
In the same way, no high environmental risks were observed such as: decrease of energy consumption, problems of substantial abatement of the emissions into the atmosphere, production of scraps/waste, water drains, etc…. All the main environmental aspects respect the normal industrial standards considered by the EU regulations. Therefore, this condition does not determine any increases of the economical costs of realisation and management of the plant in question.
In conclusion, also in this case no extra costs have been noticed and the economical risk of the process is considered minimal.
WP5 - Manufacturing plan for end item top assembly
The activity carried out in this WP is not made available, as it is highly confidential.
After defining the industrial process and manufacturing system design (degree of integration / specialization, optimal size of the plant and determination of the production capacity, optimization of plant layout and material flow, interaction with R & D), the plan will move to the formulation of the Plan of production in which all aspects of the planning and control of production will be considered. To this scope will be analyzed:
• localization of the plant and the characteristics of the ideal site,
• methods of production and production capacity compared to the needs of sales / market,
• the planning of production (orders from customers, orders from production, execution of production, controls / reprogramming), necessary equipment, packaging
• logistics either in terms of management of material flows and of intermediate goods and finished products
• identifying the number of workers needed, the skills required and relevant training programs.
• The policy of stocks of raw materials and finished products
• The quality policy, quality control on the products and the plans for quality assurance and certification,
• Vendors needed for the supply of raw materials, identify at least the main suppliers
• All permits necessary for the construction and commissioning of the plant, in particular, environmental permits (soil, water, air, etc..) and compliance plans.
The size of the plant will be of the order of productivity of 30000 tons/year, and the final items to be produced will belong to 2 different classes:
- sheets of different thickness (from 3 to 10 mm)
- pellets (thickness 2 mm, length 4 mm)
Potential Impact:
The thermoplastic and thermosetting materials reinforced with fibers that improve the mechanical behavior have been introduced on the market long time ago for restricted applications in some industrial sectors and then spread in applications increasingly common.
These materials, as a result of industrial production processes, are, at the end of their useful life, classified as "special waste" with undeniable problems in terms of disposal. From this, the great technological advantage introduced with their use on a large scale is translated, at the end of the cycle of the useful life of the product, in a serious problem both environmentally and economically.
As part of this objective, the present research proposal aims at industrial translation of a technological process developed at the National Research Council, Institute of Chemistry and Technology of Polymers, able to allow recycling and, more specifically, the reuse of these materials.
The problem is particularly acute in the aviation industry that, among those technologically advanced industries, anticipated their use on a large scale and has been proponent of evolution in terms of chemical-mechanical formulations, and pushed more both the research and the application of lightweight materials with high mechanical properties, some of which have now reached the end of their useful life for which it is indispensable disposal "aware".
The disposal of aircraft includes a series of recovery of materials by type so that at the end of the disassembly of an aircraft you already have a clear separation of materials for their composition.
Downstream of this process of dismantling and recycling, thermoplastic materials and thermosetting materials are recovered in the form of flat and/or curved plates and / of known size and repeatable so as to make the materials suitable to be subjected to successive cycles of rework essential to make them suitable to their reuse. The process involves the re-use of such materials as filler of new polystyrene-based thermoplastic materials. The potential impact of such approach (i.e. from a thermosetting to a thermoplastic composite and the confluence of two streams of end-of-life materials) is huge, particularly for a country like Italy that imports raw materials from abroad to realize goods such as furniture or building elements.
The overall objective of the dissemination activity is to disseminate the project results among three different sectors:
-Plastic manufacturers
-Entities in charge of building activities
-Scientific community
Prepare the Final Report [month 12]
1 - INTRODUCTION
The dissemination activity of the IRECE Project was carried out through many tools, including participation to international conferences with poster and oral presentations, preparation of scientific papers, realization of a Webpage.
2 - Activity performed
2.1 - WEBSITE
The webpage of the project has been realized and is available at the address:
www.ireceproject.com
2.2 - Dissemination Activity during the whole project
Participation to the Conference “Greener Aviation”, Brussels, 12th to 14th March 2014, with an invited oral presentation delivered by Mr. Fernando Bianchetti, Alenia Aermacchi. Representatives of CNR (Mario Malinconico and Maurizio Avella) and of Rs Nova Die (Antonio De Falco, Francesca De Falco) have attended the conference.
More dissemination activities are planned and will be carried out in the course of 2014, after the completion of the project IRECE. In particular, the IRECE team is attending the next conference "European Aircraft Recycling Symposium" to be held in Stuttgart on12 - 13 November 2014.
List of Websites:
www.ireceproject.com
Contact: Dr. Mario Malinconico, Institute for Polymers, Composites and Biomaterials, Consiglio Nazionale delle Ricerche (IPCB-CNR), via Campi Flegrei, 34 - 80078 Pozzuoli, Na, Italy, tel. +390818675212, Fax +390818675230, Email: mario.malinconico@ictp.cnr.it
Following the successful achievements of the Clean Sky Project SUSRAC, "Sustainable Recycling of Aircraft Composites", the IRECE project, "Industrial Recycling of CFRP by Emulsification", aimed at the development of a complete plan for the industrial production of thermoplastic highly filled composites based on Polystyrene matrix and CFRP dispersed phase, following the pilot scale demonstration.
The industrial plant has to be designed starting from the following concepts:
The carbon fibre reinforced resins (CFRP), either thermoplastic or thermosetting, are ground to different sizes and emulsified in a thermoplastic matrix in order to obtain sheets or granules. The emulsification process is carried out at room temperature (hence, cost effective) using as thermoplastic matrix Expanded Polystyrene (EPS). Such material is made widely available as result of its use as loose fill packaging for fragile goods. Moreover, its lightness (30 kg per cubic meter, on average) makes its disposal highly difficult. Combining these two streams of materials, namely CFRP and polymer matrix, the industrial process aims to obtain good performing composites and, at same time, low cost, and the industrial plant must reach these targets, but also a complete evaluation of the ecology and economy of the process.
The skills of the proponent and of the chosen partner guarantee a complete definition of all the industrial variables necessary to a complete estimation of costs and impact of the innovative production.
WPs/tasks vs. DoW in % of completion:
WP1 - Feasibility in the real industrial environment of CFRP milling and sorting It is completed at 100% in all his Tasks
WP2 - Feasibility of mixing and extruding CFRP in a thermoplastic matrix in a real industrial environment It is completed at 100% in all his Tasks
WP3 - Technical and economical impact of the selected industrial technology. It is completed at 100% in all his Tasks
WP4 - Environmental Impact and Risk Assessment of the Production cycle. It is completed at 100 % in all his Tasks
WP5 - Manufacturing plan for end item top assembly. It is completed at 100 % in all his Tasks
WP6 - Dissemination and Final Report. It is completed at 100 % in all his Tasks
WP7 - Management. It is completed at 100 % in all his Tasks
Main Resources used in the Project
Most of the resources of the Coordinator and of the Partner were employed for the activation of Research and Technical Assistance Contracts. Some resources were allocated for the participation to conferences on sustainable materials.
Project Context and Objectives:
Thermoset composite materials are used in a wide range of applications in industries such as automotive and construction. Continuous carbon fibres and epoxy resins are used for critical applications in the aerospace industry. In Europe, approximately 1 million tonnes of composites are manufactured each year. Although there are many successful uses for thermoset composite materials, recycling at the end of the life cycle is a more difficult issue. However, the perceived lack of recyclability is now increasingly important and seen as a key barrier to the development or even continued use of composite materials in some markets.
CFRP (carbon fiber reinforced thermosetting plastics), such as CF/Epoxy, has been used for aerospace fields as high strength, and light weight material. It is said the next stage of CFRP is wide spread use to many other general industrial field. Key points are the cost, the reduction of the energy consumption in manufacturing, and recycling.
Concern for the environment, both in terms of limiting the use of finite resources and the need to manage waste disposal, has led to increasing pressure to recycle materials at the end of their useful life. Where it is economically cost effective to recycle, materials recycling operations are already well established and driven by economics, for instance in the metals industries.
RECYCLING OF CFRP BY THERMOSET RESIN
The problems in recycling thermoset composites are as follows.
Thermosetting polymers are cross linked and cannot be remoulded, in contrast to thermoplastics which can easily be re-melted. Some thermosetting polymers can be converted relatively easily back to their original monomer, such as polyurethane. However, the more common thermosetting resins, such as polyester and epoxy are not practical to depolymerise to their original constituents.
Composites are by their very nature mixtures of different materials: polymer, fibrous reinforcement (glass or carbon fibre) and in many cases fillers (these may be cheap mineral powders to extend the resin or have some other function, such as fire retardants). There are few standard formulations and for most applications the type and proportion of resin, reinforcement and filler are tailored to the particular end use.
Composites are often manufactured in combination with other materials. For example there may be foam cores to reduce weight and cost or metal inserts to facilitate fastening onto other components.
In addition to these specific problems, there are the other problems associated with recycling any material from end of- life components, such as the need be able to deal with contamination and the difficulty of collecting, identifying, sorting and separating the scrap material.
A number of recycling technologies have been proposed and developed for thermoset composite materials. There are fundamentally two categories of process: those that involve mechanical comminution techniques to reduce the size of the scrap to produce recyclates; and those that use thermal processes to break the scrap down into materials and energy.
ICTP-CNR has recently developed a process for the preparation of recyclable thermoplastic composite materials with high fillers charge (60 % or above), constituted by an emulsion of recycled CFRP particles and polystyrene (PS) or ABS, tied up together thanks to a binder that guarantees the homogeneity on micro and macroscopic level and the attainment and the maintenance of the mechanical properties. It is important to underline that PS, as expanded Polystyrene (EPS) and ABS are both polymers highly present in the urban and industrial plastic wastes.
CFRP parts of end-of life aircrafts were used as CFRP waste, and the process has been proven on labscale and is being tested at pilot scale. The obtained mechanical properties, thanks to the peculiar process of emulsification, are in the range of engineering composites for structural applications (elastic modulus > 12 GPa, impact resistance > 13 KJ/m2).
Dimensional reduction of the composite was carried out by the proper grinding system, in order to get small particles. Then, the so obtained granules were mixed with fluidified polymer matrices, according to a proprietary process, aiming at producing a fluid composite containing at least 50% by weight of thermoset residue.
The obtained compounded granules can be pressed into solid plates with different thickness that find application in outdoor furnishing (tiles, flooring, etc.).
On the basis of the above achievements, the present project aims at the definition of all the steps needed to bring the process from pilot scale to a industrial phase, applying all the necessary methodologies, to those of virgin materials, but with lower cost.
WPs/tasks vs. DoW in % of completion:
WP1 is completed at 100 % in all his Tasks
WP2 is completed at 100% in all his Tasks
WP3 is completed at 100% in all his Tasks
WP4 is completed at 100 % in all his Tasks
WP5 is completed at 100 % in all his Tasks
WP6 is completed at 100 % in all his Tasks
WP7 is completed at 100 % in all his Tasks
Project Results:
The realised industrial plan allow:
• the definition of all the relevant technical, economical and environmental parameters. The industrial translation of a labscale research process involves a close relation between the group of researchers and the process engineers, in order to evaluate each single step of the innovative technology in their involvements not only technical, but also economic and environmental sustainability of choices.
• the focus on the creation of value in the context of a long-term vision. The industrial plan within the planning process, is the definition of strategies to maximize the creation of value. Often short term operational requirements do not allow companies to spend time analyzing the sectoral dynamics, the behavior of the competitors and the identification of good opportunities, the introduction and continuous improvement of the process of creating strategic, but instead contribute to create opportunities where you can develop innovative strategies that enable you to create and maintain competitive advantage. The sustainability of competitive advantage can certainly be favoured by the existence and quality of the process of drawing up business plans.
• the creation of a guide for the management of the business. The industrial plan, and more specifically the Action Plan - with the definition of the actions of the timing - is an instrument which controls the main modes of operation and in particular the entry into new markets, introducing new products and services The use of new distribution channels, the expansion of thecustomer base and the retrieval of all resources - financial, human, organizational and technological - necessary to implement the strategic objectives.
• the development of a useful learning process. The process of structuring the plan becomes a learning tool that allows you to check the quality of the possible strategies and thereby reduce the risks. In fact, the preparation of the industrial plan usually involves its progressive refinement and therefore the development of later versions in an iterative process: the assumptions are incorrect, the areas of weakness and inconsistencies are corrected so gradually, while the stimuli and insights arising from evaluation of early versions of the plan are incorporated, integrating and improving the original strategic plan. Drafting and critical review of the industrial plan are a way to be prepared to explain and defend their strategic choices in relation to the financial market in order to reduce the risk that they are not adequately understood, and for that fact alone, not approved.
WP1 Activity - Feasibility in the real industrial environment of CFRP milling and sorting
The present WP aims to show the main phases of the analysis carried out on the grinding/sorting process of composite materials made of carbon fibres; the target of the IRECE project is to consider the recovery and recycling of these materials in order to produce thermoplastic materials that will be used as secondary structures and accessories within aeronautic industry and/or other kind of products for other sector of manufacturing industry.
The IRECE project represent the natural prosecution of the SUSRAC project whose outcomes allowed the development of an experimental process in laboratory. It aims to detect all the solutions necessary to make the outcomes of the experimental phase applicable to the realization of an industrial process.
1. Technological analysis
The use of composite materials is characterized by undeniable advantages linked to their intrinsic features, such as:
• Lightness;
• Solidity;
• Fatigue resistance;
• Moulding.
These characteristics made the use of composites noteworthy in several industrial fields and especially in aeronautic industry.
The spread of these materials, though bearing countless technological advantages, presents problems connected with their disposal once worn-out.
Difficulties depend on economic expenses and on the considerable space amount needed in case of disposal in dump both of production scraps and of products and by-products resulting from dismantling and demolishing of the components realized with these materials. Therefore, it is of considerable economic and environmental importance the study and the development of industrial processes apt to use these “scraps” as raw material to realize secondary and non-structural components which would be re-employed in the aeronautic industry or in other possible sectors.
The process target of the present work involves these material as “fillers” used to create composite materials with a thermoplastic matrix in order to enable their subsequent pressing and/ or moulding to realize various auxiliary components.
The high mechanic resistance of the composite materials used as primary “filler” is the characteristic that makes more difficult the process of their reclamation and recycling. They need pre-processing finalized to grinding in order to make them usable as “filler” in the next transformation processes.
The mechanic characteristics of the material make the effects of the grinding process on the conformation of the rotors of the grinder and on its blades critical.
Analyses have been conducted in order to overcome the intrinsic difficulties of this process and to facilitate maintenance services. These analyses have been directed towards grinders with staggered edged knives in order to proceed, within the same device, with subsequent cuttings by a staggered step rotor; this way the process is split in several phases performed within the same device. In fact, the eccentric assembling of the blades allows a pre-reduction of the size of the inserted materials.
On the basis of the previous preliminary directions the choice of the type of grinding devices fell on grinders with a rotor with sectored blades and not with a single blade.
The main advantage of this kind of devices consists in the arrangement of the “knives” on the rotor, which produces a gradual impact of the sectors on the counter-blades (not a single impact rotating blade – counter blade) therefore, the production being equal, the electricity consumption results even 50% less than grinders with continue rotating blades.
The typology of rotating blades belongs to the type with constant profile, therefore after the tool grinding they do not need to be regulated on the diameter, but they can be set in their housing and locked with bolts and a torque wrench. This contributes to a considerable reduction of maintenance expenses.
Rotating blades are placed to create an helix which channels the product to grind inwards during the rotation; this allows the grindings alongside the whole rotor length.
The monitoring system of the blades allows to obtain an high flexibility in the setting of the milling process; in fact, the different kinds of blades, varying in their hardness degree, permit quick adjustments depending on the specific features of the materials actually treated. In the specific case of “carbon-fibre reinforced plastic with high Tg thermoplastic matrix or thermosetting matrix” is suggested the use of highly flexible blades in order to avoid their rapid consumption and lower maintenance expenses, increasing their actual service life.
Rotating blades will be spread on the rotor so to constantly channel the product towards the centre of the device, saving this way even the sides of the device itself, which appears still intact even after many years of work.
2. Devices research
On the basis of the data stated in the previous paragraphs, in light of the information obtained by the development phases of the SUSRAC project, it has been set going the recognition of possible suppliers of devices already operating on the market and applicable to the present project, not recurring to the realization of dedicated devices. Marketing researches led to the individuation of at least three possible producers of “grinding lines” with suitable features.
The producers will not be identified by name, they are all Italian owned companies, and are:
• Producer 1;
• Producer 2;
• Producer 3.
On the basis of the information given (grinding material features, time capacity…) only two
producers have made an offer and have supplied characteristics:
• Producer 2;
• Producer 3.
Both producers have identified as devices suiting the process requirements a grinding line able to work, for the specific material treated, within a range of 1.000÷1.500 kg/h, whilst only the Producer 3 proposed also a line able to work within a range of 4.000÷5.000 kg/h.
The products proposed are based on different technologies:
• Producer 2 proposed a “two-stage” system;
• Producer 3 proposed a “one-stage” system.
Depending on the two different technologies proposed (“two-stage” and “one-stage”) it is not proper to realize a detailed compared analysis of the two line types proposed; nevertheless it is possible to compare their energy requirements on the basis of the set up electric power.
Considering the offers and the technical files attached, it follows that the set up electric powers in the analysed cases are:
• “Two-stage” line = 150 kW;
• “One-stage” line = 132 kW;
involving a clear advantage of the “one-stage” line in terms of energy engaged on the whole during a type year of the working plant.
3. Solution proposed
The preliminary energetic analyses carried out in the previous paragraphs suggest that the best solution to take, on the basis of the information and features supplied by some producers of grinding lines, is the implementation of n. 5 grinding lines with a maximum potential of 5 t/h.
This solution has undeniable advantages, not only concerning energy:
• The reduction of the obstacles on map both for “one-stage” and even more “two-stage” solution;
• Margin of extra productive capacity of about 2.250 kg/h that, projected over the whole yearly
productive cycle, allows to treat up to 33.000 t/year with a margin of the 10% compared to the initial datum of the project and without any other investments.
Considering the possible powder emission in the environment, mills will be installed in a soundproof cabin each constantly kept in depression by a system of powder demolition connected also to the grinding chambers.
Likewise the power supply chambers will be connected to the network of the dust removal systems in order to avoid any powder leakage.
WP2 - Feasibility of mixing and extruding CFRP in a thermoplastic matrix in a real industrial environment
1 - Process Data
According to the SUSRAC project that represents the origin of the present work, the transformation and re-use process of CFRP coming from aircraft dismantling, production scraps and/or other industrial sources, is based on the creation of a gel solution of EPS and emulsifier. In this solution powders and/or ground parts of CFRP are dispersed in order to produce a mixture composed, in its final configuration, by the 70% by wt of CFRP and the 30% of EPS.
This relation represents the characterization of the product; nevertheless other mixtures are possible, for instance the one with 60% of CFRP and 40% of EPS. It is evident that, reducing the CFRP percentages, the mechanical characteristics of the finished product decrease; for this reason the mixture composed by the 70% of CFRP and 30% of EPS has been chosen as the reference for the design of the plant. In this way the greatest mechanical characteristics are guaranteed for the final product.
The process consists in the solubilization of EPS in emulsifier to create a gel where it is possible to disperse the recycled fibers coming from the grinding process discussed in the WP1.
In order to reach the complete dissolution of EPS, the mixing ratio Emulsifier/EPS is assumed equal to 1.5 in the present work.
2 - Pre-design of the production cycle
The production cycle of a whole day has to be designed to handle 37.500 kg/day of CFRP coming from the grinding plant; this value has been chosen to respect the hypothesis of annual production mentioned in the previous paragraph.
Considering the following mixing ratios:
• EPS = 30% by weight of the output;
• CFRP = 70% by weight of the output;
along with the weight ratio emulsifier/EPS necessary to the formation of the gel, it is possible to proceed to the determination of the volumes needed for one work shift in the hypothesis already mentioned.
The CFRP to handle in a whole work shift is equal to 37500 kg, then the required amount of EPS is 16100 kg; for the dissolution of such a quantity of EPS, almost 24150 kg of emulsifier are necessary.
3 - Mixing system
Since the masses and the densities necessary to the process development are known, it is possible to evaluate the volumes of the materials involved in the process:
• CFRP = 37500/1500 = 25 mc;
• EPS (apparent volume) = 16100/30 = 540 mc;
• EPS (volume in dissolution) = 16100/1050 = 16 mc;
• Emulsifier = 24150/740 = 33 mc.
Since the difference between the EPS volumes (before and after the solubilization) is remarkable, the loading sequence of the reactor consists in the immersion of the whole quantity of emulsifier, followed by the introduction of EPS.
In this way EPS contributes with its intrinsic volume to the formation of the gel, decreasing
considerably the volume of the mixer.
On the basis of the data already reported, it is possible to determine the theoretical reaction volume that is 75 mc.
Considering the necessity of disposing of volumes capable of allowing future improvements, increasing the general reliability of the system and assuring a suitable agitation of the product in the mixing phase, it is considered worthwhile to divide the total quantity in n.3 reactors with a single minimum capacity of 30 mc, for a total of 90 mc.
The reactors are made of stainless steel (AISI 304) with an inner multi-blade agitator (rotors distributed on four levels at least) made of the same material. In the spaces not occupied by the helixes, fixed counter-blades are arranged (installed on the reactor plating) to create a counter-rotating action opposed to the one of the main blades. This action guarantees a total and fast mixing of the materials.
4 - Storage and supply of emulsifier
The emulsifier can be of two types: virgin, coming from the outwards, or recycled, coming from the further production phases. In both cases, the emulsifier is stored in specific tanks outside the plant. In order to guarantee correct conditions of security and conservation of emulsifier, the storage tanks are kept in overpressure by flushing with inert gas (typically nitrogen).
The transfer of the emulsifier from the storage tanks to the mixers is guaranteed by process pumps with the body in stainless steel certified ATEX. These pumps are installed outside near the storage tank area.
For the design of the storage tank area, the following hypothesis are considered:
• Recovery in the phases of mechanical pressing = 65÷70%;
• Recovery in the phase of drying in oven = 30 ÷ 25%; the process losses and/or portions of emulsifier not recoverable are within the range 5 ÷ 10%.
In a conservative hypothesis of recovery and re-use of emulsifier equal to the 90% of the required total quantity, it is possible to evaluate the amount to replenish for each production week. In light of the above mentioned assumptions, the total weekly emulsifier requirement is 165 mc/week. To guarantee this requirement, it is necessary to arrange a weekly integration of 16.5 mc in addition to the 33 mc needed for the normal operation of the production cycle.
Therefore it is required to have a total emulsifier reserve of 33 + 16.5 = 49.5 mc.
It is proposed the realization of a tank park with an overall capacity of 70 mc, able to assure the correct implementation of the production cycle for n. 2 weeks. The storage tanks of the recovered emulsifier represent the first supply source of the reactors whereas the tank of virgin emulsifier is the second source to be used only when the quantity of recycled emulsifier is finished.
The flow rate of the pumps must allow the filling of each reactor (about 11 mc) in a maximum time of 30’; hence the nominal flow rate of each pump is equal to 25 mc/h with an approximate hydraulic head of 3 bar. The transfer lines made of stainless steel (AISI 304) are realized with drawn pipes welded together. Only the couplings with the process equipment (pumps, tanks, reactors, …) are realized with flanged systems.
The replenishment of the three mixers is executed in sequence in order to reduce the instantaneous flow rate of the pumps and the filling time of each mixer; in this way it is decreased the time of the whole cycle. Furthermore, the possibility of a differential filling of the three mixers allows to reduce the starting time of the plants, from the beginning of the work shifts.
5 - Storage and supply of EPS
The correct and complete execution of the process requires a daily amount of EPS of about 16100 kg.
In order to assure a functional autonomy for n. 1 week, the storage of such material is of 80500 kg and, since the EPS apparent density is 30 kg/mc, it corresponds to a minimum storage volume of about 2700 mc of EPS.
Considering the significant dimension of the storage of this material, it is assumed the realization of a dedicated rectangular shaped warehouse with a surface of 2000 m2 where it is possible to store about 160,000 kg of EPS sufficient to guarantee the production for 2 weeks. At one end of the warehouse (the one towards the production plant), it is planned the realization of an underground loading hopper from which the pneumatic transfer system for the convoy of the EPS to the mixers originates.
The pneumatic transfer system is of mixed type: in depression in the aspiration phase from the loading hopper, and in pressure during the unloading of the material in the loading hopper of the mixer. That solution allows two actions: the containment of the aspiration of EPS volatiles from the mixer when the slide valve (located at the unloading nozzle of the cyclone separator of the EPS); the reduction of possible problems of generation of bridges in same phase.
The parts of the pneumatic transfer system, that are in contact with the product, are made of stainless steel AISI304.
The single piping lines and all the other parts installed on them to form the whole pneumatic transfer system, are interlinked guaranteeing the electrical continuity and they are connected to the ground in order to avoid the accumulation of electrostatic charges and also the dispersion to the ground of possible failure currents.
NOTE: the necessity of storage and supply of the EPS may be eliminated in the hypothesis of a sampling and emulsification of the EPS realized directly near the accumulation areas of the packaging scraps, through a mobile or fixed platform. In this way, the gel of EPS/emulsifier arrives directly to the realization plant of the compounds, ready to be mixed with the CFRP fillers.
Storage and supply of CFRP
After the grinding process illustrated in the WP1, the CFRP is conveyed to a storage system composed by vertical silos.
Since the theoretical capacity of each grinding line is 5000 kg/h and considering that the plant functionality should be guaranteed for two consecutive weeks, the storage capacity must be 375000 kg of CFRP. As a consequence the necessary storage volume is equal to 250 mc.
That total quantity is divided in n.3 silos, each of them with a capacity of about 90 mc in order to have a free space at the top that compensates the irregular distribution of the material in the filling phase.
The partition of the material in n.3 silos allows the realization of devices with moderate dimensions (ø = 3.0 m; h » 13.0 m).
The type of pneumatic transfer considered for the CFRP is the same used for the transport of EPS; the only variation is the introduction of regulations about the radii of curvature to use in the changes of direction of the transfer lines, taking account of the particular mechanical characteristics of the carried material.
Pneumatic transfer systems
The pneumatic transfer systems considered for the handling of both CFRP and EPS are conveyed to dedicated mechanical filtration systems with bag and cartridge filters for the mechanical separation of the possible suspended particles not removed by the cyclonic systems at the service of the plants.
Following the mechanical separation systems, appropriate hydraulic seals and active carbon filters are planned for the total separation of the emulsifier particles airborne in the currents. In the same way, systems of hydraulic seals and active carbon filters are considered for the air valves of the main storage tanks and of the mixers.
Production of semi-finished panels
After the supplying and mixing systems previously illustrated, the process involves the casting phase of the “filled gel” and the subsequent production of the panels that form the intermediate semi-finished product.
The production stage of the semi-finished panels is characterized by the following elementary phases:
• Dosage and casting of the “filled gel”;
• Mechanical compaction of the “filled gel” to form sheets with a narrow quantity of emulsifier;
• Stripping of the remains of emulsifier in order to form the “dry” semi-finished panel to forward to the next stage of thermoplastic formation.
It is called attention to some similarities between the production process of the semi-finished panel in EPS+CFRP and the production cycle of the paper. In fact, the “filled gel” presents, for its workability, characteristics similar to the ones of the paper. For the latter the consolidated processes involve the separation by pressing the water in which the cellulose fibers and other additives are dispersed. Instead for the EPS+CFRP the removal of emulsifier always occurs by mechanical means.
Dosage and casting of the “filled gel”
At the end of the mixing process the casting and formation phase of the semi-finished panel starts. This stage begins with the opening of the slide valve of the mixer. The transfer of the “filled gel” is conducted by a gear pump. The choice of this type of pump depends on its specific functional
characteristic that guarantees the constancy of the volumetric flow rate on varying the rpm. In fact, the volumetric flow rate is not influenced by the pressure drops of the casting circuit and also by the hydraulic head of the mixer, the density and viscosity of the obtained mixture, etc. In this way, it is possible to modify the thickness of the panel simply operating on the rotational speed of the gear pump, leaving unchanged all the other operation parameters of the production line.
The casting of the gel occurs on a metallic conveyor belt through a linear system composed by a calibrated and adjustable opening.
The “filled gel” is casted on the conveyor belt with a thickness in a range of 0.5-1.0 cm.
Mechanical compaction of the “filled gel”
After the casting station discussed in the previous paragraph, counter-rotating rollers are installed in the upper part of specific rollers of the transfer system, with distances decreasing gradually, with the function of pressers/compactors.
At that stage almost the 70% of the initial amount of emulsifier in the “filled gel” is removed by mechanical means. This phase typically involves a volume reduction within the 30% and 35% with the consequent separation of the 60÷70% of the total contained emulsifier. The removed emulsifier is recovered in dedicated basins collocated under the mechanical compaction stations in order to be later re-conveyed in the main storage tanks allowing its re-use in the next phases of the production process.
The recycling cycle of the emulsifier is considered continuous, then the volume of the recovering basins is about 3 mc with the only aim to assure a correct management of the pouring phases through pumping systems characterized by appropriate transfer times, without requesting the continuous working of the transfer pumps.
Removal of residual emulsifier
Following the process of the mechanical extraction of emulsifier, it is necessary to guarantee the total removal of the residual emulsifier from the semi-finished product in order to allow the achievement of the mechanical characteristics required for the further re-use.
The removal of residual emulsifier may be implemented by taking advantage of two characteristics of this solvent:
• High solubility in water;
• Volatility concurrent with the low boiling point.
The two processes are essentially different and are illustrated below.
Stripping of emulsifier in water
Regarding this process, some tests have been carried out to evaluate the transfer kinetics of emulsifier to water.
The tests executed on laboratory samples have underlined that the release time of emulsifier in water, in order to guarantee the almost total removal, is of about 24 h.
In the hypothesis of the considered production process , the volume of the whole material to handle for each working shift is about 15 mc divided in the following way:
• CFRP = 25 mc;
• EPS = 16 mc;
• Emulsifier = 10 mc.
In order to assure an appropriate contact surface, it is assumed that between the several layers of semi-finished product a free space of 2 cm is left to allow a correct water flow. Under the hypothesis of semi-finished panels with a thickness of 0.5 cm after the process of “mechanical compaction of the filled gel”, it is necessary to have a total volume of water equal to 200 mc and containment basins with a net useful capacity of 251 mc at least. For a more flexible process, it is planned the realization of n.3 stripping basins of emulsifier, each of them with a volume of 150 mc. The presence of the third basin is essential to guarantee the load in the unloading phase of the first busy basin.
Furthermore, that basin functions also as a buffer tank in case it is necessary to increase the permanence time of the semi-finished product in water in order to maximize the stripping of the emulsifier.
It must be highlighted that such a process involves the need of proceeding to a treatment of distillation of the water used to separate the emulsifier, which cannot enter in the environment once dissolved in water.
From laboratory tests carried out to estimate the transfer kinetics of emulsifier to water, it may be noticed that, despite the previous mechanical elimination, the total removal is achievable with a permanence time of about 24 h, confirming that the necessity of at least n.3 basins is fully justified to guarantee the continuity of the production cycle.
The exam of the results related to the transfer kinetics of emulsifier to water shows the need to consider a following drying stage in a ventilated oven at 80°C in order to assure both the removal of the residual emulsifier and the drying of the water possibly absorbed during the period of immersion in water.
From the study of the transfer kinetics of emulsifier in a convention oven at 80°C, it is possible to observe that the complete elimination of the water occurs in 1 hour time in case of the absence of the immersion cycle in water. Assuming a total cycle time (product loading, warming, drying/evaporation, cooling, product unloading) of about 2h, it is planned the installation of n.2 convection ovens with a capacity of about 10mc. In this way, it is possible to dispose the loading with an interval of 1h. This solution corresponds to a saturation at the 100% of the production capacity of the ovens, then the installation of a third oven is considered to assure a suitable reserve in order to guarantee the correct working also during ordinary and/or extra maintenance of one of the ovens.
Stripping of emulsifier in oven
Following the results of the tests executed for the evaluation of the elimination kinetics of emulsifier with hot process in a ventilated oven, it is observed that the total elimination time of the solvent is below 1h from the reaching of the temperature of 80°C inside the cell.
This result suggests the utilization, as an alternative to the cycle previously illustrated, of a cycle that completely eliminates the stripping phase of emulsifier in water, opting for the direct insertion in oven of the semi-finished product after the mechanical removal of emulsifier through calendaring.
Even in this case, the results of the laboratory tests confirm that the total removal of the residual emulsifier is achieved in about 1 hour. Considering a cycle time (product loading, pre-warming, extraction time, cooling, product unloading) of about 3h, the oven system may be replaced by n.2 ovens with a single capacity of 15 mc able to satisfy the 100% of the production capacity of the mixing systems and of the casting and mechanical calendering line of the semi-finished product.
Recovery of emulsifier from the drain
Whether considering the stripping of emulsifier in water or in oven, there are problems in the recovery of the emulsifier removed from the product. In the case of removal in water, it is necessary to proceed to the recovery through distillation, then it is essential to consider appropriate storage areas and a process to execute outside the production plant. Instead in the other case, in order to recycle the emulsifier contained in the exhaust air from the convention ovens, it is possible to realize in situ a recovery system based on an exchanger-chiller supplied on the primary circuit by chilled water at high temperature (about 15°C).
WP3 - Technical and economical impact of the selected industrial technology
The present Workpage aims to evaluate the technical and economical impact of the pre industrialisation of the recycling process of composites made of CFRP (carbon fiber reinforced polymer). There will be individuated the minimum conditions to obtain a process that is economically competitive. From a preliminary market survey, the resulting reference scenario points out the absence of suitable plants for the treatment of fuselages and other aircrafts waste. As a consequence, the companies that own aircrafts have the economical disadvantage of incurring expenses to dispose the scraps as special waste. Furthermore the disposal operations are in contrast with the national and EU waste legislation which prefers the reuse and/or the recycling of scraps.
In particular there will be analysed the costs to bear for the realisation of the industrial line and the costs and the availability of waste to treat, eventually determining a profit and loss account.
Availability and costs of disposal
The project factor used in the design of the plant is based on an a maximum annual availability of recycled CFRP equal to 30,000 ton/year, then the annual production capacity of the grinding phase is 6,000 ton/year (daily capacity of 37.5 ton/year, process efficiency equal to 80% for 220 days/year). The existing market survey allows to determine that the disposal of dismantled aircrafts costs about 200 €/ton for it is necessary to commit it to companies specialized in the treatment of special waste. Since the energy content of such materials is low (for the high amount of incombustible carbon fiber), in the current scenario the most probable destination for this material is the landfill.
Consideration and assumption for the logistic and location of the plant In order to individuate the most suitable areas for the location of the plant, it is necessary to examine the geographical sites of the needed waste matters (CFRP,EPS). In fact, one of the essential factor for the cheapness of the production chain is an economically convenient supply of CFRP and EPS.
At this proposal, Italy was assumed as the country for the logistic and location of the plant considerations.
In particular in the south of Italy, the greatest available amounts of waste CFRP are located in the fuselage production area that is Grottaglie (TA). A second supply area is Pomigliano d’Arco (NA) where is available a smaller percentage of waste CFRP coming from the Alenia Aermacchi factories.
Concerning the EPS to recover, the supply is possible through the provision of scraps of EPS, free of contaminations and/or residuals, coming from other production chains ( i.e. appliances, building, etc….). In this case the raw material is available in a wider and more distributed geographical area, although it is possible to pinpoint some areas with a greater concentration of EPS: the big commercial areas and the industrial zones where there is the production of appliances and electronic components.
Considering the specific weight of the materials to recover (CFRP and EPS) and their location areas, it is essential to locate the plant near the EPS supply areas in order to obtain an efficient and economically convenient supply chain management. In fact the EPS has a substantial transfer cost because it is very light, whereas the transfer of CFRP is less onerous thanks to its high density.
In the present case, since the daily use of EPS is 16.1 ton/day, it is necessary the recovery of large amounts of EPS (about 3,220 ton/year). Therefore the decrease of the EPS supply costs is essential.
For the above mentioned reasons, one suitable location of the recycling plant could be the Caserta area where there are several and big shopping centres and an important industrial production area.
Analysis of the costs of the plant
The plant is composed by the following equipment:
• Grinders;
• CFRP storage silos;
• Warehouse of 2000 m2 for the storage of EPS and the housing oh the production line;
• Emulsifier storage tanks;
• Mixing reactors;
• Transfer systems;
• Mechanical pressing system with recovery of emulsifier (about 70%);
• Stripping system with ventilated ovens and condensation of the emulsifier (25%).
Analysis of the operating costs
The main operating costs related to the working of the treatment plant are divided in the following way:
• Personnel costs
For the running of the recycling plant, n. 10 employees are needed with the tasks listed below:
## N. 1 Chief of Production Department, holding a degree in engineering to employ “full time” for an annual gross cost of 50,000 €/year.
## N. 2 Process Technicians, graduated from industrial technical institutes specialised in chemistry or mechanics, with a “full time” contract. A technician is employed in the control room, the other one on the production lines. The annual gross cost for each technician is equal to 35,000 €/year.
## N. 2 Workers for the loading of raw materials and the unloading of packed products at the end of the process. The contract is “full time” and the annual gross cost for each worker is 26,000 €/year.
## N. 2 Workers for the grinding phase of the CFRP, to employ “full time”. The annual gross cost for each worker is 26,000 €/year.
## N. 3 Workers for the mixing phase and the stripping of emulsifier, to employ “full time”. The annual gross cost for each worker is 26,000 €/year.
The total gross personnel cost is about 302,000 €/year.
• Costs of the materials used in the production cycle
The input materials of the plant are: emulsifier, expanded polystyrene (EPS) and CFRP.
• Management, maintenance and financial costs
An item, regarding the costs of maintenance and consumables, is considered in the operating costs. It is evaluated in percentage regarding the cost of the plant.
The item contains:
- Ordinary and extra maintenance service carried by external personnel;
- Cost of the moving of goods linked to the logistic in entrance and exit;
- Small equipments for the warehouse and the workshop.
The operating costs only consider the industrial costs; in fact the following costs are not taken into account:
the general expenses, the accounting and administrative costs, possible costs due to the management of the considered business area.
Concerning the financial costs, a coverage of the financial requirement has been hypothesized. The financial requirement is related to both the fixed capital and the working one for the year 0, necessary for the realisation and the finalizing of the plant.
Evaluation of the investment payback
Nowadays, the sale price of the product on the market is equal to 4 €/kg but, if the production of recycled
CFRP increases, this price will decrease. For this reason three hypotheses about the market price are contemplated:
- Worst: sale price 0.5 €/kg;
- Medium: sale price 1.00 €/kg;
- Best: sale price 2.00 €/kg.
The cash flows, reported in the above mentioned attachments, have been discounted at a WACC equal to the supposed financial cost, that is 4.50%.
In conclusion, in the worst hypothesis the payback period is about 4.5 years whereas in the medium and best cases is lower than 3 years.
WP4 - Environmental Impact and Risk Assessment of the Production cycle
The Workpage aims to evaluate the general environmental impact of the productive process under consideration. In particular, the environmental impact of the final product and the impact related to the settled working activity will be verified. This approach has the purpose to confirm that the process is coherent with the objectives of respect of the environment , not only in terms of the current relevant regulations but mainly referring to the environmental benefits of the whole process. The environmental analysis will allow to proceed with the evaluation of the risks of the productive process, from an economical and environmental point of view.
The analysis is composed by a systematic diagnosis that studies deeply all the relations between the productive activities of the process and the environmental and territorial reality that surrounds it.
Thank to this analysis, it is possible to reach an overall evaluation of the environmental problems connected to the activity. Therefore it represents the starting point for the identification of the objectives and the procedures to be implemented by the company.
The environmental analysis must pinpoint:
- The direct and indirect aspects ( environmental aspect: element of an activity, product or service of an organization that can interact with the environment);
- The significant impacts (environmental impact: any alteration of the environment, negative or good, total or partial, resulting from an activity, product or service of an organization).
It is composed by the following actions:
- Identification of the environmental regulations applicable to the activities conducted in a company, for the compliance check regarding prescriptions and authorizations;
- Identification of the most significant impacts on which it is necessary to focus the targets of improvement and the evaluation of the size of the environmental impacts on the territory.
In addition, the analysis also includes the examination of all the procedures and practices that will involve the company in the environmental field and the evaluation of the analysis of the environmental incidents that can happen.
Methodological approach
The environmental analysis is divided in n. 4 stages:
• STAGE 1 – General analysis: the information concerning the production site, the type of business in question and the sector environmental regulations, is gathered;
• STAGE 2 – Identification of the environmental subjects: the environmental aspects in question are identified and analysed along with their compliance with the conducted working activity and the regulations;
• STAGE 3 – Evaluation of the environmental subjects: analysis of the impact that the environmental aspects of the process have in relation to the operators and the territory where the company works.
• STAGE 4 – Conclusions: a classification of the analysed environmental aspects is carried out identifying the reference environmental indicators necessary to pursue the expected objectives of protection.
CONCLUSIONS
For each process activity, the environmental aspects in the different operating conditions have been identified. Now, for each environmental aspect, the significance of the environmental impacts is evaluated with the criteria illustrated below:
• Classification of the impacts on the process:
- Low = 1 point
- Medium = 3 points
- High = 5 points
• Significance index of the activity:
- Low < = 15 points
- 15 points < Medium < = 20 points
- High > 20 points
Risk Assessment
As defined by the current regulations about the occupational safety (Directive 99/92/CE, for Italy D. Lgs. 81/08), the aim of the risk assessment is to organise all the necessary measures for the protection of the safety and the health of the workers. Its main tasks are:
1. Identifying all the sources of danger and evaluating their possible effect on the workers;
2. Removing or at least reducing the risk factors;
3. In case of non eradicable risks, providing suitable personal protective equipment to the exposed workers;
4. Planning and realizing the necessary information and training courses about the risks;
5. Organising all the activities needed to be in compliance with the regulations.
In the present report, the measures necessary to assure the best safety conditions are analysed in relation to the characteristics of the production line for the recycling of CFRP and EPS.
The measure will be identified considering the following sections:
a) Identification of the general, specific and emergency measures of protection;
b) List of risk factors and results of the risk forecasting;
c) Improvement factors of the levels of protection during time.
- Identification of the general, specific and emergency measures of protection
In this section the following aspects are analysed: the working place, the tasks of the workers and the used equipments. The objective is to identify the measures to implement in order to prevent and reduce the risks connected to the working conditions that can cause cross dangers, not placed inside a group of specific risks.
Considering the characteristics of the process in question, the general measures to implement are:
1. Correct information and training of the workers about the possible risks that can affect them. There will be organised theoretical-practical courses that explain the right conditions of use of the equipments and the materials involved in the process;
2. Arrangement of an appropriate system of management of the tasks in the different production phases, in order to restrict the possible exposure at risk factors;
3. Correct training about how to use the personal protective equipments (PPE) and identification of a team that manage emergencies and medical aid.
The specific measures are related to the particular criticality of rooms, machines, equipments and or/systems.
- List of risk factors and results of the risk forecasting
The criteria of analysis and evaluation are ground on the objective analysis of the criticalities found by evaluating the actual probability of occurrence of an injury, or of a damage to the health and safety of the workers. This probability is related to the seriousness caused by the damage due to the occurring of the event. The scale of the probabilities of occurrence of a dangerous event and its relative damage have the same quantitative definition, in order to make homogeneous the evaluation of the risk factor.
Then, it is necessary to evaluate possible criticalities of equipments, plants, structures and every factor that can represent a source of danger.
For the assignation of the values of the probability of occurrence of a dangerous event and of its consequent damage, the following sources have been consulted: data already present and relative to the used materials and equipments; technical rules, models, current regulations.
The risks have been divided into three groups:
• CROSS AND ORGANISATIONAL RISKS: they come from the criticalities related to the organisation of the tasks, working shifts, the treadmill of the tasks with repeated mechanical actions; criticalities due to the difference of category.
• SAFETY RISKS: all the risks that can compromise the safety of workers during the execution of their tasks. Among them, the following risks are classified: fire, flood, earthquakes, machines that expose to risks of trauma, cut or general injuries, explosions, plants, work equipment.
• HEALTH RISKS: in this category there are the risks connected to the exposure at chemical and/or physical (noise, vibrations, E.M. fields, etc…), or to the healthiness of rooms, sanitary conditions, microclimate and in general all the factors that can compromise the health of workers in case of extended exposure to the above mentioned agents.
During the phase of analysis and evaluation, the exposure of single workers (belonging to the same homogeneous area) to the above listed risks have been considered; the origin of potential risks has been identified, the opportune measures of prevention and protection have been listed along with the necessary means of individual protection.
- Identification of sources of danger and risks factors
In this phase the tasks of the single workers are identified, dividing them in homogeneous areas.
An homogeneous area is the set of activities associated for similarity of situations or tasks (competence, operational tools, environmental characteristics), and for which the exposure of workers to safety, health and cross risks are ascribable to similar factors.
Technical-economical risks related to the technology involved in the process
In addition to the risks concerning the health of the workers and the protection of the environment, another analysis is considered. Starting from the results of the deliverable D3.1 (Technical and economical impact) the analysis identify, and sometimes assess, the possible technical-economical risks connected to the technologies used in the process.
In fact, some potential technological risks were already identified in the preliminary study phases of the process. Some specific “emergency plans” should be considered for each risks.
These technological risks concerns:
- The storage and securing of CFRP;
- The mixing and pressing of the mixture CFRP+EPS+Emulsifier.
As already seen, it is possible to buy and use all the machines and equipments necessary to the phases of the process, starting from the existing technologies already used in other industrial fields (i.e. chemistry, building materials, plastic components etc…).
Then, no extra-costs have been noticed and the economical risks for the realisation and use of the production line can be considered minimal.
In the same way, no high environmental risks were observed such as: decrease of energy consumption, problems of substantial abatement of the emissions into the atmosphere, production of scraps/waste, water drains, etc…. All the main environmental aspects respect the normal industrial standards considered by the EU regulations. Therefore, this condition does not determine any increases of the economical costs of realisation and management of the plant in question.
In conclusion, also in this case no extra costs have been noticed and the economical risk of the process is considered minimal.
WP5 - Manufacturing plan for end item top assembly
The activity carried out in this WP is not made available, as it is highly confidential.
After defining the industrial process and manufacturing system design (degree of integration / specialization, optimal size of the plant and determination of the production capacity, optimization of plant layout and material flow, interaction with R & D), the plan will move to the formulation of the Plan of production in which all aspects of the planning and control of production will be considered. To this scope will be analyzed:
• localization of the plant and the characteristics of the ideal site,
• methods of production and production capacity compared to the needs of sales / market,
• the planning of production (orders from customers, orders from production, execution of production, controls / reprogramming), necessary equipment, packaging
• logistics either in terms of management of material flows and of intermediate goods and finished products
• identifying the number of workers needed, the skills required and relevant training programs.
• The policy of stocks of raw materials and finished products
• The quality policy, quality control on the products and the plans for quality assurance and certification,
• Vendors needed for the supply of raw materials, identify at least the main suppliers
• All permits necessary for the construction and commissioning of the plant, in particular, environmental permits (soil, water, air, etc..) and compliance plans.
The size of the plant will be of the order of productivity of 30000 tons/year, and the final items to be produced will belong to 2 different classes:
- sheets of different thickness (from 3 to 10 mm)
- pellets (thickness 2 mm, length 4 mm)
Potential Impact:
The thermoplastic and thermosetting materials reinforced with fibers that improve the mechanical behavior have been introduced on the market long time ago for restricted applications in some industrial sectors and then spread in applications increasingly common.
These materials, as a result of industrial production processes, are, at the end of their useful life, classified as "special waste" with undeniable problems in terms of disposal. From this, the great technological advantage introduced with their use on a large scale is translated, at the end of the cycle of the useful life of the product, in a serious problem both environmentally and economically.
As part of this objective, the present research proposal aims at industrial translation of a technological process developed at the National Research Council, Institute of Chemistry and Technology of Polymers, able to allow recycling and, more specifically, the reuse of these materials.
The problem is particularly acute in the aviation industry that, among those technologically advanced industries, anticipated their use on a large scale and has been proponent of evolution in terms of chemical-mechanical formulations, and pushed more both the research and the application of lightweight materials with high mechanical properties, some of which have now reached the end of their useful life for which it is indispensable disposal "aware".
The disposal of aircraft includes a series of recovery of materials by type so that at the end of the disassembly of an aircraft you already have a clear separation of materials for their composition.
Downstream of this process of dismantling and recycling, thermoplastic materials and thermosetting materials are recovered in the form of flat and/or curved plates and / of known size and repeatable so as to make the materials suitable to be subjected to successive cycles of rework essential to make them suitable to their reuse. The process involves the re-use of such materials as filler of new polystyrene-based thermoplastic materials. The potential impact of such approach (i.e. from a thermosetting to a thermoplastic composite and the confluence of two streams of end-of-life materials) is huge, particularly for a country like Italy that imports raw materials from abroad to realize goods such as furniture or building elements.
The overall objective of the dissemination activity is to disseminate the project results among three different sectors:
-Plastic manufacturers
-Entities in charge of building activities
-Scientific community
Prepare the Final Report [month 12]
1 - INTRODUCTION
The dissemination activity of the IRECE Project was carried out through many tools, including participation to international conferences with poster and oral presentations, preparation of scientific papers, realization of a Webpage.
2 - Activity performed
2.1 - WEBSITE
The webpage of the project has been realized and is available at the address:
www.ireceproject.com
2.2 - Dissemination Activity during the whole project
Participation to the Conference “Greener Aviation”, Brussels, 12th to 14th March 2014, with an invited oral presentation delivered by Mr. Fernando Bianchetti, Alenia Aermacchi. Representatives of CNR (Mario Malinconico and Maurizio Avella) and of Rs Nova Die (Antonio De Falco, Francesca De Falco) have attended the conference.
More dissemination activities are planned and will be carried out in the course of 2014, after the completion of the project IRECE. In particular, the IRECE team is attending the next conference "European Aircraft Recycling Symposium" to be held in Stuttgart on12 - 13 November 2014.
List of Websites:
www.ireceproject.com
Contact: Dr. Mario Malinconico, Institute for Polymers, Composites and Biomaterials, Consiglio Nazionale delle Ricerche (IPCB-CNR), via Campi Flegrei, 34 - 80078 Pozzuoli, Na, Italy, tel. +390818675212, Fax +390818675230, Email: mario.malinconico@ictp.cnr.it