Unformatted text preview: The use of Life Cycle Engineering within the design process of production facilities A business case: Different options of handling overspray at the new rear axle paint shop at DaimlerChrysler in Mettingen.
Marc Binder1 ([email protected]) Johannes Kreissig1 ([email protected]) Executive summary At DaimlerChrysler it is planned to replace the current paint shop of the rear axles by a new one. It is the goal to design the new paint shop representing the latest technology for paint shops and overspray handling and to consider ecological, technical and economic aspects from a life cycle perspective during the design process. Therefore the Life Cycle Engineering approach (LCE) has been chosen to give a broad view and compare the different options. The application of LCE within the design phase has shown that the reaction time for feedback is reasonable for designers and therefore can be applied within the planning of new production facilities. The LCE study showed that there is no direct relation between the economic results and the ecological performance of a design option. While all considered recycling systems have better economics than the considered options only allowing energy recovery of the collected overspray, there is no general preference regarding pro/contra recycling from an ecological point of view. Life Cycle Engineering (LCE) integrated in the design process LCE methodology is evaluating ecological, technical and economic aspects considering the total life cycle of processes/products. LCE studies are based on material and energy flow information needed while running the facilities or for producing products. LCE is a simulation tool analyzing weak points and show optimization potentials as well as supporting the decision making process within the design phase. As various databases hold information on ecological impacts of material- and energy production, so called ecoprofiles, and information on the economic values is available within the involved companies, time consuming research on basic materials and energies is not necessary anymore. Therefore first estimations on scenarios can be made within days to support the decision process not causing any time delay of the process.
1 PE Europe GmbH, Hauptstrae 111-113, 70771 Leinfelden-Echterdingen, www.pe-europe.com Tel.: +49 711 341817 0, Fax: +49 711 341817 25 LCE studies can be conducted within the design process and on existing facilities/products. If LCE is used within the design process optimization potentials can be shown in early stages of the design phase of facilities/products. Integration of LCE within early stages of the design ensures an efficient way of improving the ecological profile of processes and products and reducing the overall costs considering the total life cycle. Realization within the software tool GaBi42 The software tool GaBi4 is developed and designed to support LCE efficiently and in a transparent way. The design of the facilities can be modeled according to the material and energy flow. All boundary conditions, e.g. efficiencies, time of operation, climatic boundary conditions, emissions to air, water and soil etc., can be modeled as parameters. This enables the user to run simulations within different boundary conditions using the base model for all scenarios of interest. The business case - Goal and scope It is planned to replace the current paint shop for painting the rear axles at the DaimlerChrysler facilities in Mettingen by a new one. The new facilities should contain the latest technology for paint shops and overspray handling. Currently, the rear axles are painted with a solvent based paint for corrosion protection. Due the several reasons, e.g. direct VOC emissions of the paint shop, new concepts for corrosion protection have been analyzed. The new concept consists of a layer of water based paint and a layer of conservation material (also water-based). During the design phase different options for the overspray handling and for the layer of water based paint have been analyzed considering technical, ecological and economic aspects. Goal of this study was to gain knowledge on the environmental effects associated with the different concepts for handling the overspray and the different water based paint option considering the total life cycle (from production of the paint system through the application and the handling of the overspray). Additional focus has been set on the economic differences of the different design option considering also the total life cycle. The study has been conducted to meet the goal of considering the three dimensions, technology, ecology and economy, during the decision making process. 2 GaBi4 software and database for Life Cycle Engineering ( www.gabi-software.com ) Boundary conditions - description of design option for handling the overspray The functional unit of the study of the ecological part has been the painting of the rear axle with water based paint including handling of overspray, thermal post combustion (TNV) and the conditioning of supplied air etc. The boundary conditions are shown within Figure 1.
Emissions to air, soil and water Painted rear axle
Boundary conditions Conditioning of supply air if required by option for overspray handling Oversprayhandling Treatment of exhaust air Energy recovery Overspray Exhaust air of dryer Paint shop incl. dryer Production of External energy Auxilliaries Intermediates Production of paint Recycling of Overspray Rear axle, not painted Figure 1: Boundary conditions The economic analysis is focusing on the differences of the different design options and 20 years of operation. The focus of the economic part has been in the following issues: Investment costs Cost of operation (e.g. power, water, natural gas, wear parts etc.) Material costs Logistic- and storage costs Labor costs (e.g. operation, maintenance, training etc.) Labor specific equipment (e.g. protection clothes etc.) Controlling and quality assurance Transport- and storage packaging Reporting (e.g. audits etc.) Waste treatment (e.g. landfill, recycling) Waste water treatment Emissions to air (e.g. filter, TNV etc.) Area related costs (e.g. rent, overhead etc.) The paint shop has been modeled based on information provided by Sturm3 and Drr4. Information on the water based paint has been provided by Schramm coatings5. The following different options for handling the overspray have been considered and analyzed: a) ULF circulating filter b) Relac/ULF c) Relas d) Turbo Coolac ULF circulating filter ULF consists of a housing of galvanized sheet steel with integrated filter and extractor boxes, endless circulation filter fleece, drive system and "dust collector" unit. Plastic laminated strips are used to pre-filter and dry the paint mist. The core of the ULF technology is a circulating filter fleece which does not absorb the paint overspray but only catches it and conveys it to the extractor point. In the ULF a special fleece performs this task very efficiently. The relatively thin, air-permeable filter is only a transport medium, air handling capacity and air speed remain constant. The dry material is collected in a replaceable container and can be disposed of easily. Paint which adheres to the plastic laminated strips is simply peeled off like a skin. Subsequent filtering with a so-called "police filter" is often superfluous, as up to 99% of the overspray can be extracted and collected dry in one cleaning process.9
Solvent of overspray Particles Brainflash Brainflash6 Reiter7 Range & Heine8 paint component
overspray Particles of overspray Dry overspray (emissions to environment) ULF Circulating filter Exhaust air filter Dry overspray within exhaust filter Air for pneumatic cylinder Power for supply- and exhaust air ventilation Power for radial ventilation Dust collection Dry Overspray (collected within container) Figure 2: ULF system
3 4 http://www.sturm-gmbh.de http://www.durr.com 5 http://www.schramm-coatings.de 6 http://www.brainflash.at 7 http://www.reiter-oft.de 8 http://www.range-heine.de 9 http://www.brainflash.at/Webseiten/0231funktione.html Relac/ULF The Relac /ULF options is a combination of the Relac- and a ULF system. The overspray which is not collected by the Relac system is handled by the ULF system. The technical heart of the RELAC recycling system is a conveyor belt behind the workpiece. It catches the paint overspray, and deflector blades strip off the material before it dries. More than 90% of the overspray can be reclaimed immediately. Adjustment of the viscosity and addition of volatile components can be carried out during the reclamation process. The reclaimed material is filtered and blended with new paint or passed directly to the coating process. A multistage dry separation system is used to clean the exhaust air. In enclosed cabin systems, sensors monitor and control the air intake for optimum coating conditions. In the case of water-based paint systems, the plant can be operated in 90% recirculating air. When solvents are being used, the exhaust air heat can be recycled by means of plate heat exchangers.10
Recycled material Solvent of overspray Particles paint component
overspray particles Dry overspray (emissions to environment) Circulating filter Exhaust air filter Dry overspray within exhaust filter Relac ULF Power for RELAC system Air for pneumatic cylinder Power for supply- and exhaust air ventilation Power for radial ventilation Dust collection Dry overspray (collected within container) Figure 3: Relac/ULF system Relas The Relas system is, like the ULF system, a system for dry deposition and placed also behind the component which is painted. Between 70 % and 80 % of the overspray is collected by the "lamellar curtain" and will be scraped of by a metal blade. The recovered material can be either landfilled, send to energy recovery or send back to the material producer. The overspray which is not collected by the Relas system will be filtered by exhaust air filters.
10 http://www.brainflash.at/Webseiten/0211funktione.html Turbo Coolac Turbo Coolac is a wet separation system with the goal to recycle the collected overspray. The system is illustrated within Figure 4 and consists of a separation surface, a cyclone, a cold water production device, collection containers and an exhaust air ventilator (not illustrated within Figure 4). Cyclone Separation surface Cold water production device Collection container
Figure 4: Turbo Coolac To avoid that the material is drying on the separation surface, the temperature of the surface is cooled below the dew point of the cabin. This condition is created by conditioning of the cabin and cooling of the surfaces. Due to the cooling the humidity is condensing at the collection surface and the overspray reaching it stays liquid and is pouring into the collection container. The part of the overspray which is not collected by the separation surface will be handled by the cyclone. The air stream containing the overspray is aspirated by the cyclone and the particles are separated using the centrifugal force. Due to the fact that the surface of the cyclone is also cooled, the overspray condensates at the surface and can be collected by the collection containers. The collected material can be either recycled by the material producer or mixed to virgin material (adding volatile components to meet the viscose requirements). Execution of study This chapter is about who needs to been involved, the information flow within the project, effort for the participants and challenges within the project. To perform an evaluation of new design of production facilities considering the ecological and economic point of view along the total life cycle the following parties have to be involved: a) Customer, e.g. DaimlerChrysler Planning department of production facilities Environmental department Technical staff, e.g. testing if recycled material meets technical specification Purchasing b) Developing companies of different design options: Designer Sales c) Material supplier Technical staff, e.g. testing if recovered material can be recycled Sales d) LCE consultant Technical staff to conduct the study, e.g. modeling within LCE software, analysis of results, trustee of confidential information of participating companies etc. LCE studies highly depend on the cooperation of the different participating companies. Most of the participants are concerned regarding confidential information and the effort they have to put in to make the analysis successful. During the course of the project the concerns mostly disappeared due to the fact that the project partners realizes that most of the information needed is not confidential. No confidential information on the different technologies was needed to perform this study. In case confidential information on material composition was needed to perform the study, e.g. composition of paint, the LCE consultant acted as a kind of trustee. No confidential data on recipes of the paint is needed to be displayed to the other project partners, due to the fact that the ecological profile of the used material, e.g. paint, will be only one part of the overall environmental profile of a specific option. Within this study the corporation of each project partner and the willingness to provide inform has been really good. The effort everybody had to put in had been hold to a minimum as no extensive investigation to gather the information needed for creating the LCA and cost model had to be done by the participating companies. Most information was already available. The information only had to be collected from internal sources within the companies and provided to the consultant11. The following list represents the most relevant information the analysis is based on: Amount of paint needed Amount and specification of energy need for running the process Percentage of overspray Life time of wear parts / paint shop
11 PE Europe GmbH; www.pe-europe.com Efforts/benefits of scenarios handling the overspray, e.g. recycling, energy recovery Assessment of direct process emissions to environment ... Exemplary results Within this chapter the results are discussed in a qualitative way. (Options 1 to 4 do not necessarily follow the order of the description of the systems.) The analysis of the results has shown, that the impact of the different life cycle stages to different impact categories vary. It is therefore important to analyze the whole life cycle and more than one impact category. As shown within Figure 5, the operation phase of option 4 has a significant influence on the overall primary energy demand (approximately 25 %) while the operation of option 1 and 2 are negligible. Primary energy demand (PE)
100% 80% 60% 40% 20% 0% Option 1 -20% Option 2 Option 3 Option 4 energy recovery operation of paint shop material production thermal post combustion Figure 5: Primary energy demand of selected options Within Figure 6 the different share to the GWP are shown. If you compare Figure 5 and Figure 6 it can be seen, that the share of the material to the overall results are significantly different analyzing option 1 and 2. While the contribution to the overall PE of the material is approximately 35 % the share of the GWP is only approximately 25 %. Also it can be seen, that there is a benefit assigned to the energy recovery looking at PE while there is a contribution to the global warming potential. This is due to the fact, that the thermal efficiency of the energy recovery options are less than the production of thermal energy and electricity not by energy recovery. Global Warming Potential (GWP)
100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Option 1 Option 2 Option 3 Option 4 energy recovery operation of paint shop material production thermal post combustion Figure 6: Global Warming Potential of selected options Analyzing Figure 7, which illustrates different scenarios for handling the exhaust air, it can be said that the thermal treatment of the exhaust air of the paint cabin results in a significant increase of the primary energy demand. This is due to the fact that the average temperature of the cabin exhaust air was estimated with 22C and therefore and increased amount of natural gas was required to "burn" it. Primary energy demand
140% 120% 100% 80% 60% 40% 20% 0% thermal post combustion of dryer exhaust air incl. heat recovery thermal post combustion of dryer/paintcabin exhaust air incl. heat recovery no thermal post combustion; heating of circulating air by thermal energy Figure 7: Primary energy demand of different scenarios handling exhaust air Analyzing the POCP shows that the direct emissions of the solvent are dominating this impact category. Depending on the fact how many solvents will stay within the overspray, up to 80% of the POCP is related to the direct emissions of the paint shop. Within Figure 8 three different scenarios of option 3 are illustrated. The different scenarios represent different percentages of solvent emitting from the overspray within the paint cabin. "100" means all solvents will be released to the environment, while "25" means only 25 % will be emitted. If the exhaust air of the cabin would be treated by a thermal post combustion also, the POCP of the operation of the paint shop would be nearly "0" and the overall POCP would decrease significantly, see option 2. Photochemical Ozone Creation Potential (POCP)
100% 80% 60% 40% 20% 0% Option 2 -20% Option 3 "25" Option 3 "50" Option 3 "100" energy recovery operation of paint shop material production thermal post combustion Figure 8: POCP different assumptions The following conclusions can be drawn based on the analysis of the ecological part of study: Recycling options are not always the preferable options. Thermal post combustion of the dryer exhaust air makes sense if the heat will be recovered. If the photochemical ozone creation potential (POCP) is the primary focus, a thermal combustion of the exhaust air loaded with solvents makes sense in any case. The actual solvent emissions have to be measured, e.g. at pilot plants, due to the fact that they have an influence on the evaluation. A large amount of solvent emissions will have the following influence on the overall results: o o Higher photochemical ozone creation potential (POCP) if the cabin exhaust air is not treated by a thermal post combustion, or Significant increase of the primary energy demand (PE) and the other impact categories if the cabin exhaust air is treated by a thermal post combustion. Analyzing the economic part of the study, the following conclusions can be drawn: Even having higher costs for investment, the analyzed recycling option show advantages compared to the options with energy recovery of the collected overspray. The reduction of costs due to the use of recycling material is significant. The cost for landfill for the collected "paint dust" is not negligible (at least in Germany). The cost for operation do have an influence on the overall economic results and each option has different contributors within the operation phase to the overall operating cost. Therefore the operating costs should be analyzed in detail. The cost for disposal of the wear parts are negligible. The time for amortization of the higher investment costs of the recycling systems showed to be between 1 and 12 years. Should the exhaust air of the dryer be treated by a thermal post combustion and the produced heat be recovered, the additional costs due to increased gas consumption can be neglected. Should the exhaust air of the paint cabin be treated by a thermal post combustion, the increase of cost are of significance. Based on a lifetime of 20 years, recycling systems are preferable from an economic point of view compared to options which do not allow recycling of the collected paint material. Summery The application of LCE using the established LCE software GaBi 4 within the planning of facilities showed, that: a systems approach (life cycle) gives a broad view and comparison of different options from an economic and ecological point of view, the willingness of suppliers to provide information is there, the effort in time and cost is reasonable compared to the reduction potential the reaction time for feedback is reasonable for designers of facilities and therefore the LCE approach can be applied within the planning of new production facilities. The results of the study showed, that there is no direct relation between economic results and ecological performance of an option. all considering recycling systems have better economics than the options only allowing energy recovery of the collected overspray there is no general preference regarding pro/contra recycling from an ecological point of view. ...
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This note was uploaded on 08/06/2008 for the course ESM 289 taught by Professor Geyer during the Spring '07 term at UCSB.
- Spring '07