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
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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.
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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
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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
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