United States Environmental Protection Agency Research and Development Risk Reduction Engineering Laboratory Cincinnati, OH 45268 EPA/600/S-92/047 October 1992 ENVIRONMENTAL RESEARCH BRIEF Waste Reduction Activities and Options for a Manufacturer of Commercial Refrigeration Units Kevin Gashlin and Daniel J. Watts* Abstract The U.S. Environmental Protection Agency (EPA) funded a project with the New Jersey Department of Environmental Protection and Energy (NJDEPE) to assist in conducting waste minimization as- sessments at 30 small- to medium-sized businesses in the state of New Jersey. One of the sites selected was a facility that manufac- tures commercial refrigeration units. The manufacturing operations include design, metal working, metal finishing, and bbwing of poly- urethane foam into panel jacketing for insulation purposes. A site visit was made in 1990 during which several opportunities for waste minimization were identified. Options identified included new tech- niques to reduce CFC emissions from foam manufacture, new foam production cleaning techniques to reduce methylene chloride usage, improved painting techniques to reduce VOC emissbns, and reduc- tion of solvent wastes from general cleaning procedures. Imple- mentation of the identified waste minimization opportunities was not part of the program. Percent waste reduction, net annual savings, implementation costs and payback periods were estimated. This Research Brief was developed by the Principal Investiga- tors and EPA's Risk Reduction Engineering Laboratory in Cin- cinnati, OH, to announce key findings of this completed as- sessment. Introduction The environmental issues facing industry today have expanded considerably beyond traditional concerns. Wastewater, air emissions, potential soil and groundwater contamination, solid waste disposal, and employee health and safety have become increasingly important concerns. The management and dis- posal of hazardous substances, including both process-related * New Jersey Institute of Technology, Newark, NJ 07102 wastes and residues from waste treatment, receive significant attention because of regulation and economics. As environmental issues have become more complex, the strategies for waste management and control have become more systematic and integrated. The positive role of waste minimization and pollution preventbn within industrial operations at each stage of product life is recognized throughout the world. An ideal goal is to manufacture products while generat- ing the least amount of waste possible. The Hazardous Waste Advisement Program (HWAP) of the Division of Hazardous Waste Management, NJDEPE, is pursu- ing the goals of waste minimization awareness and program implementation in the state. HWAP, with the help of an EPA grant from the Risk Reduction Engineering Laboratory, con- ducted an Assessment of Reduction and Recycling Opportuni- ties for Hazardous Waste (ARROW) project. ARROW was designed to assess waste minimization potential across a broad range of New Jersey industries. The project targeted 30 sites to perform waste minimization assessments following the approach outlined in EPA's Waste Minimization Opportunity Assessment Manual (EPA/625/7-88/003). Under contract to NJDEPE, the Hazardous Substance Management Research Center at the New Jersey Institute of Technology (NJIT) as- sisted in conducting the assessments. This research brief presents an assessment of the manufacturing of commercial refrigeration units (1 of the 30 assessments performed) and provides recommendations for waste minimization options re- sulting from the assessment. Methodology of Assessments The assessment process was coordinated by a team of techni- cal staff from NJIT with experience in process operations, basic chemistry, and environmental concerns and needs. Be- Printed on Recycled Paper ------- cause the EPA waste minimization manual is designed to be primarily applied by the in-house staff of the facility, the degree of involvement of the NJIT team varied according to the ease with which the facility staff could apply the manual. In some cases, NJIT's role was to provide advice. In others, NJIT conducted essentially the entire evaluation. The goal of the project was to encourage participation in the assessment process by management and staff at the facility. To do this, the participants were encouraged to proceed through the organizational steps outlined in the manual. These steps can be summarized as follows: • Obtaining corporate commitment to a waste minimization initiative • Organizing a task force or similar group to carry out the assessment • Developing a policy statement regarding waste minimiza- tion for issuance by corporate management • Establishing tentative waste reduction goals to be achieved by the program • Identifying waste-generating sites and processes • Conducting a detailed site inspection • Developing a list of options which may lead to the waste reduction goal • Formally analyzing the feasibility of the various options • Measuring the effectiveness of the options and continuing the assessment. Not every facility was able to follow these steps as presented. In each case, however, the identification of waste-generating sites and processes, detailed site inspections, and development of options was carried out. Frequently, it was necessary for a high degree of involvement by NJIT to accomplish these steps. Two common reasons for needing outside participation were a shortage of technical staff within the company and a need to develop an agenda for technical action before corporate com- mitment and policy statements could be obtained. It was not a goal of the ARROW project to participate in the feasibility analysis or implementation steps. However, NJIT offered to provide advice for feasibility analysis if requested. In each case, the NJIT team made several site visits to the facility. Initially, visits were made to explain the EPA manual and to encourage the facility through the organizational stages. If delays and complications developed, the team offered assis- tance in the technical review, inspections, and option develop- ment. No sampling or laboratory analysis was undertaken as part of these assessments. Facility Background The facility is a manufacturer of commercial refrigeration units typically used for food storage and sale. The manufacturing process involves creation of the metal framework and surfaces of the final unit, priming and painting of the unit, installation of the refrigeration components, and blowing in polyurethane foam which hardens into rigid insulation. The facility is located in an urban area and employs 200-300 people. Manufacturing Processes The production process for the refrigeration units can be divided into three general sections—sheet metal cutting and forming, metal coating and curing, and blowing of foam insulation. Each of the steps results in the creation of different types of waste. The sheet metal cutting and forming step involves cutting, punching, and molding to form the desired shape for the unit. While this portion of the manufacturing process does not directly result in significant quantities of waste (particularly because care is taken in laying out metal pieces to minimize any waste from that source) the machinery used to accomplish the metal cutting and forming does require maintenance. This machinery care results in the generation of about 1,400 gal of waste lubricating oil each year. This oil comes from the engine and gear box oil changes. The cut and formed metal is finished in three stages, all of which are required to provide the type and quality of finish desired by the manufacturer. The first step is degreasing of the metal surface using a hot caustic cleaner. The degreasing is necessary to remove the anti-oxidant protective oils which are applied to the sheet metal to prevent corrosion between the sheet metal manufacture and the time it is used. The second step is priming the metal using zinc phosphate. The zinc facilitates the retention of the finish coat to the metal surface. The finishing coat is a high solid, solvent-based paint. The color of the paint applied varies depending upon customer request. This variability results in frequent color changes on the manufacturing line. The paint is sprayed on using an electrostatic system reported to be approximately 81% effi- cient. When necessary the paint is thinned using isobutylcarbitol. Equipment is cleaned as required by the color changes. Xylol is used to clean pumps and other auxiliary equipment, and toluol is used to clean the hoses leading to the spray system from the paint reservoir. The insulating polyurethane foam is produced at the facility by combining a polyol, diphenylmethane diisocyanate, and trichlorofluoromethane (R-11). While the exact formulation is proprietary, it is known that the R-11 represents about 10% of the mix. In addition, another chlorofluorocarbon, R-12, is used to blow the mixture into the steel panel jacketing. R-11 is encased in the cured solid structure of the mixture and, because of its heat transfer characteristics, helps provide the insulating characteristics of the mixture. According to the supplier of the chemicals used for generation of the polyurethane foam, about 40% of the R-11 and R-12 used in the process escapes into the air during the manufacture and curing phases and cannot be reduced significantly without development of new foaming technology. The foam mixture cures very rapidly. The residual mix adhering to the foam blowing equipment would also cure and harden within a few minutes thereby ruining the equipment. To prevent this from occurring, the equipment is cleaned with 0.5 to 1.0 gal of methylene chloride after each unit is insulated. About 13,000 Ib of the washing mixture is generated annually. Emis- sions of methylene chloride to the air from evaporation have not been quantified. Existing Waste Management Activities The company has already invested in equipment which is designed to improve efficiency and help prevent pollution. The acquisition of the electrostatic painting equipment demonstrates the interest by the company in improving the efficiency of the paint transfer process and in reducing the proportion of the material which is wasted. ------- The waste lubricating oil from maintenance and repai; of the machinery used in metal cutting and shaping is collected and sent offsite for disposal. The annual volume of oil is about 1,400 gal. The oil changes generally occur at regularly sched- uled intervals. The waste stream from the degreasing operation has an an- nual volume of about 2900 Ib and is also sent offsile for treatment. The waste streams from the coating operations are somewhat more complex. Excess primer and solids from surface smoothing are captured in water and then filtered out before the bulk of the water is sent to the sewerage authority for treatment. Information about the volume of water from this use could not be obtained The quantity of the filtered solids represents about 500 Ib/yr. This appeared to be too small an amount to lead to consideration of metal >eoovery activities. The finish coat process uses a paint which ha? a high solids content and is solvent-based. The high solids means that the solvent content is relatively low (2.1-2.8 Ib/gal). Performance require- ments will not allow the substitute use of a water-based paint at this time. There is not a substitute product available which will albw the manufacturer to maintain the quality of the finish coat of the p-oduct. As indicated previously, the paint is sprayed on using an electro- static system. When the painting equipment is cleaned, xyloi B used to clean the pumps and other auxiliary equipment and toluo is used to clean the hoses leading to the spray system from the paint reservoir. The two solvent wastes are combined, accumulated in drums and disposed of as hazardous waste. About 18,000 gai of this waste is generated annually. The insulating foam production operation generates a waste stream from the cleaning of the generation and blowing equipment. About 13,000 Ib of the methylene chloride washings are generate annu- ally and are sent offsite for disposal as hazardous waste. Waste Minimization Opportunities The type of waste currently generated by the facility, the sojrce of the waste, the quantity of the waste and the annual treatment and disposal costs are given in Table 1. This particular facility presents a challenge in terms of describing and presenting opportunities for waste minimization. For example, the production of the polyurethane insulating foam results in a measurable waste stream only in terms of clean up solvents. On the other hand, there is a process related air emission of a CFC which is thought to be of significant environ- mental concern. The available technological alternatives present some difficulties. Similarly, some improvements in the painting pro- cess will require significant capital investment in equipment which Table 1. Summary of Current Waste Generation Waste Generated Waste Oil Water/Hydrocarbon Mixture Zinc Containing Solids Hydrocarbon Mixture (Toluol and Xytol) Methylene Chloride Solution Source of Waste Repair and maintenance of meta' cutting and forming equipment Hot caustic degreasing operation Residues and smoothing solids from priming operation Equipment cleaning from spray painting Cleaning of polyurethane foam generation system cannot be easily quantified presently based upon the information currently available. Table 2 shows the opportunities for waste minimization recom- mended for the facility. The type of waste, the minimization opportu- nity, the possible waste reduction and associated savings, and the implementation cost along with the payback time are given in the table. The quantities of waste currently generated at the facility and possible waste reduction depend on the level of activity of the facility. All values should be considered in that context. It should be noted that the economic savings of the minimization opportunity, in most cases, results from the need for less raw material and from reduced present and future costs associated with waste treatment and disposal. It should also be noted that the savings given for each opportunity reflect the savings achievable when implementing each waste minimization opportunity indepen- dently and do not reflect duplication of savings that would result when the opportunities are implemented in a package. The cost savings are calculated both in terms of avoided costs of waste disposal and recovery of any value of raw material used again. Also, no equipment depreciation is factored into the calculations. There are some commercially available alternatives to the present insulating foam process. The insulating process requires a gas for two purposes, one to generate foaming during the polymerization process and another to force the foam, prior to hardening, into the area where insulation is required. The CFC's that are presently being used do this job well. The relatively low boiling point leads to the foaming as a result of vaporization caused by the heat of reaction of the polymerization. Some of the CFC is entrained in the foam and contributes to the insulation performance of the product. The use of other materials may result in loss of this added boost to the insulating characteristics of the foam. One of the available alternative technologies uses a hydrochlorofluorocarbon (HCFC) as the blowing agent. This class of materials has reduced impact on the upper atmosphere as compared to CFC's. The propulsion gas used in this system is nitrogen. Another alternative uses a proprietary composition and mixing approach which appears to use nitrogen as both blowing and propulsion agent. The cost of raw materials and equipment for this application is approximately the same as the currently used CFC technology. However, the insulation effective- ness of the resulting foam is only about 95% that of the existing foam material. This means that either the refrigeration units need to be redesigned to allow incorporation of an increased thickness of insulation or that the units will be in operation for longer periods. Either way more energy will be used because additional units may Annual Quantity Generated 1,400 gal 2,900lb 500 Ib 18,000 gal 13.000 Ib Annual Waste Management Costs $600 3200 250 22,000 16,000 ------- Table 2. Summary of Recommended Waste Minimization Opportunities Minimization Opportunity Annual Waste Reduction Waste Stream Reduced Quantity Percent Net Implementation Payback Annual Savings Cost Years Waste Oil Hydrocarbon Mixture Methylene Chloride Solution Change to synthetic formula to lengthen time between oil changes Keep separate the xylol and toluol streams. Acquire onsite distillation capability. Reuse Change to less hazardous solvent cleaning system available from the vendor of the polyurethane components. The newer solvent can be filtered and reused, reducing the need to purchase and dispose of cleaning solvent. 700 gal 14,400 gal 13,000 Ib 50 80 100 $850 31,000 $2,800 20,000 3.3 0.6 19,400 5,000 0.25 (This option is somewhat more complex in the determination of savings and payback period. While all of the methylene chloride waste stream will be eliminated, another waste stream will be established. However, without some site experience, it is difficult to estimate the volume. If we assume an 80% reduction in the volume because of recycling and assume that disposal costs and chemical costs are the same as with methylene chloride, then the annual savings are $ 15,800 and the pay back period will be 0.3 yr. There will also be another waste stream resulting from the filtration of solids from the recycled solvent. Management costs for that stream will also reduce the net savings.) ' Savings result from reduced raw material and treatment and disposal costs when implementing each minimization opportunity independently. be required to refrigerate the same volume of material or the refrigeration equipment will run bnger. It is difficult to determine, at this level of analysis, which choice is more environmentally favor- able. However, the rapid escalation of CFG taxes and the impending ban on production and use of the materials will require a change at this facility. It appeared that the electrostatic paint system which had been installed needed some additional adjustments in order to operate at its maximum high transfer efficiency. For some painting operations, portions of the spray were directed at areas where there was not metal to be painted resulting in a bss of the paint and increased VOC burdens. It is suggested that the number of spray nozzles be increased resulting in more precise control of the area being covered by paint. In addition, use of an optical recognition and control system could result in more savings. Discussions with the manufacturer of the painting system and with suppliers of optical control systems will be necessary to determine if this is feasible and to obtain a cost estimate. Other coating alternatives should continue to be investigated. It is likely that none of them would be acceptable at present because of performance requirements. On the other hand, progress in broaden- ing the technology of coating materials should be monitored. The goal of such changes is to reduce the level of VOC and associated hazardous waste streams. Powder coating virtually eliminates sol- vent, and any overspray is simply swept up and reused. The capital costs are comparable to those of the electrostatic spray system just acquired by the company. Another emerging technology utilizes supercritical carbon dioxide as the carrier for the solids in coatings. The coating system requires special equipment for production of the supercritical carbon dioxide. Generally, up to 70% of the volatile solvents can be replaced resulting in VOC reductions of the same amount. Additionally, it is reported that superior atomization occurs using this technology relative to solvent systems, resulting in fewer spraying defects. Regulatory Implications Changes in regulatory emphasis can be expected to have an impact on the manufacturing process at this facility. Particularly, the im- pending ban on production and use of most CFC's will cause a change in the production of the insulating foam. The technical and chemical details of this change are largely out of the hands of the company. They will acquire the equipment and supplies from some- one else. In terms of the volume of waste generated at the facility, it is not clear whether this impending change will have a net positive or negative effect. It may take larger quantities of some solvent to clean the required equipment for example. The point is that regulatory changes do not always albw uniform movement to waste reduction. This is particularly true when cross media transfers of waste genera- tion are considered. A change in a process such as this which has air emissions and may require a change in an air permit may be delayed while the air permitting process considers and approves (or disapproves) the application for a change. This facility will also be impacted by the increased regulatory scrutiny on methylene chbride. There are some alternatives available for this solvent which is used for cleaning purposes at this facility. It is not clear however, without some field trials whether the net effect on waste generatbn will be positive or negative. Methylene chloride is a particularly good solvent for the cleaning application here. This Research Brief summarizes a part of the work done under cooperative Agreement No. CR-815165 by the New Jersey Institute of Technology under the sponsorship of the New Jersey Department of Environmental Protection and Energy and the U.S. Environmental Protection Agency. The EPA Project Officer was Mary Ann Curran. She can be reached at: Pollution Prevention Research Branch Risk Reduction Engineering Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 ' Mention of trade names or commercial products does not constitute endorsement or recommendation for use. •&U.S. GOVERNMENT PRINTING OFFICE: 1994 - 5SO-067/ttOI93 ------- |