VIBRATORY SPIRAL
BLANCHER-COOLER
EXECUTIVE SUMMARY
U.S. ENVIRONMENTAL PROTECTION AGENCY
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
CINCINNATI-
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INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
VIBRATORY SPIRAL
BLANCHER-COOLER
EXECUTIVE SUMMARY
by
John L. Bomben, J.S. Hudson, W.C. Dietrich,
E.L. Durkee, D.F- Farkas
Western Regional Research Center
Science and Education Administration
U.S. Department of Agriculture
Berkeley, California 94710
and
Richard Rand, J.W. Farquhar
American Frozen Food Institute
McLean, Virginia 22101
Grant No. S-803312
Project Officer
Donald L. Wilson
Food and Wood Products Branch
Industrial Pollution Control Division
Cincinnati, Ohio 45268
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DISCLAIMER
This Executive Summary has been reviewed by the Industrial
Environmental Research Laboratory-Cincinnati, U.S. Environmental
Protection Agency, and approved for publication. Approval does
not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
The Executive Summary is published with the intent of pro-
viding quick and concise information on the results and findings
of'this project. - In this context, revjew has been kept to a mini
mum. The Final Report has been published under the same title as
an ORD Series 2 report (600/2-78-206).
ACKNOWLEDGEMENT
The Executive Summary Report was prepared by SCS Engineers,
Long Beach, California, under Contract No. 68-03-2578. The EPA
Project Officer on the original grant was Harold W. Thompson.
For further information on this project, contact the Food and
Wood Products Branch, Industrial Pollution Control Division,
Industrial Environmental Research Laboratory, Cincinnati, Ohio.
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VIBRATORY SPIRAL
BLANCHER-COOLER
- EXECUTIVE SUMMARY -
SIGNIFICANCE
The frozen food industry, faced with increasing water
pollution control and energy costs, evaluated a unique vege-
table blanching and cooling unit called a vibratory spiral
blancher-cool er. The study indicated that the unit could
significantly-reduce hydraulic and organic wasteloads when
compared to the conventional water blanching, flume cooling
process. In addition, a doubling o-f current combined costs of
utilities and waste treatment would place operating costs on a
par with conventional blanching.
The results indicated that a variety of vegetables,
including snap beans, lima beans, broccoli, brussels sprouts,
and cauliflower, could be processed through the unit. Full
production for the latter three vegetables, however, would have
to be accompanied by several design modifications.
No attempt was made in the cost estimate calculations to
account for the loss of vegetable weight attributable to the
air cooling section of the unit.
T •
If frozen vegetables are valued at $440/kkg ($0.20/lb), a
2 percent loss of yield resulting from air cooling as compared
to flume cooling would add the equivalent of $8.80/kkg to the
cost of blanching and cooling since frozen vegetables are
marketed by weight. Such a large penalty for air cooling can-
not be economically justified. A standard other than weight
for marketing frozen vegetables (e.g., number of vegetables per
package or total solids per package) would be required to take
full advantage of the wastewater reduction possible with air
cooling. One should also note that at a price of $440/kkg for
frozen vegetables, the entire cost of blanching and cooling is
less than 2 percent of the cost of production. The small
impact of blanching and cooling on the total cost of production
gives the processor little economic incentive for capital
investment in new blanchers or coolers.
HIGHLIGHTS OF PROJECT FINDINGS
Linked with federal legislative requirements to reduce
wastewater effluent and the increasing cost of energy, the
prototype of a new bl ancher-cool er for the vegetable freezing
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industry recently underwent testing under actual plant proces-
sing conditions. The new unit (vibratory spiral blancher-
cooler) was developed from previous pilot plant work which
indicated the unit could simultaneously reduce wasteloads
and conserve energy.
Snap beans and lima beans were tested over two processing
seasons; a few brief experimental runs with brussels sprouts,
cauliflower, and broccoli were done during one season.
The unit met almost all design projections for snap beans
and lima beans, reducing both volume and organic content of
wastewater, showing an energy efficiency 17 times greater than
conventional steam blanching equipment, and producing a product
that was equal to, or in some cases, of better quality than
conventionally processed product.
The operating costs of the vibratory spiral blancher-
cooler were higher than those of a conventional water blancher
flume-cooler system. If utility costs were to double, however,
the operating costs of the two systems would be equal.
The prototype unit was large enough to represent a typical
full-scale production unit, so no further larger scale testing
is required; designs for units 5 to 10 times the capacity are
available. Processing vegetables other than snap beans and
lima beans would require some equipment modification.
The project indicated that the system could also be used
in processing vegetables for canning, where cooling after
blanching is not required; the blanching effluent might have
use as a.canning brine, thus further reducing wasteloads.
CAPSULE PROJECT SUMMARY
The prototype of a newly-designed-type blancher-cooler for
the vegetable processing and freezing industry was tested under
actual plant conditions. The objectives were:
• To measure the system's overall effectiveness in
reducing wasteloads and energy consumption
0 To evaluate the system's vibratory conveyor on a
variety of vegetables.
Some of the more important features incorporated in the
design were:
• Use of steam blancher condensate as a spray during air
cooling to reduce wasteloads from both blanching and
cooling operations
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• Use of air cooling to replace conventional water or
flume cooling to reduce the organic wasteload produced
by the leaching of solids
• Flexibility to transport blanched vegetables through an
inclined or declined (up-flow or down-flow) vibratory
spiral conveyor during the cooling operation.
• Incorporation of Individual Quick Blanching (IQB) tech-
niques to provide additional means of reducing the
overall size of the blancher.
The unit consisted of six sections: feeder, heater,
holder, cooler, air blower with filter, and condensate spray
system. Figure 1 presents a simplified schematic of the
design.
The prototype was operated in two modes. In 1975, vege-
tables were conveyed upward through the cooling spiral; in
1976, product was conveyed downward through the cooling spiral.
The down-flow arrangement was necessary since the vibratory
conveyor could not successfully move the vegetables upward.
The prototype vibratory blancher-cooler was based on
earlier work done at the Western Regional-Research Center, U.S.
Department of Agriculture, Berkeley, California, and was manu-
factured by the Rexnord Corporation. The prototype unit was
installed at Patterson Frozen Foods, Patterson, California, and
was evaluated from August 1975 to January 1977.
Results of the Study
Table 1 presents a summary of energy use and costs (total
capital and annual O&M) for the prototype unit and four other
blanching techniques. Each technique was evaluated for snap
beans at a capacity of 4.5 kkg/hr (5 T/hr) with a 2.0 min
blanch time. The data indicated the following:
• The steam efficiency of the blancher was 85 percent, or
17 times better than the measured efficiency of a con-
ventional steam blancher.
.•? -
• Total investment costs for a vibratory spiral blancher
were approximately four times those of a conventional
water blancher ($82,000 vs $20,000). The addition of
air cooling to the vibratory spiral blancher increased
the investment costs by $92,000 or 53 percent of the
total capital Investment; the addition of flume cool-
ing to the conventional water blancher increased capi-
tal investment costs by $80,000 (29 percent).
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RAW
VEGETABLES
FEEDER
STEAM
HEATER
AND HOLDER
AIR
O
EFFLUENTf
COOLER
^BLANCHED
& COOLED
VEGETABLES
CONDENSATE SPRAY SYSTEM
Figure 1. Schematic diagram of vibratory spiral blancher-cooler.
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TABLE 1. SUMMARY OF ENERGY USE AND COSTS OF FIVE BLANCHING TECHNIQUES
Blanching Techniques
Theoretical
Vibratory Blancher-Cooler
Conventional Steam Blancher
Hydrostatic Steam Blancher
Hot-Gas Blanching
Conventional Mater Blancher
Energy Use
Steam Requirements
(kg/kkg)
134
158
2,580
500
240
—
Costs
Efficiency
(«)
100
85
»
5
27
56
60
•
Total Capital
Investment Costs
(SxlOOO)
__
. . *
(82)
--
147
229
(20)*
Annual O&M
Costs
($/kkg)
__
5.50
—
9.04
8.76
4.12
Cost of blancher only shown In parentheses.
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• Although operating costs of the vibratory spiral
bllancher-cooler were higher than those of a conven-
tional water blancher flume-cooler system, doubling the
combined costs of fuel, water, and waste treatment
would make annual operating costs of the two processes
equal.
Additional results of the prototype testing on snap beans
and lima beans showed that:
• The unit, when compared to conventional water blanching
and flume cooling, reduced the hydraulic wasteload by
several orders of magnitude, and the organic wasteload
by as much as 80 percent.
• • With the product flowing through the cooler in a
downward mode, the vibratory spiral blancher-cooler
processed more than 2,000 kg/hr of snap beans and more
than 1,200 kg/hr of lima beans, far exceeding its
design capacity of 900 kg/hr. Minor equipment modifi-
cations would be required to reach full capacity with
broccoli, brussels sprouts, and cauliflower.
t The unit was easy to clean after use. Microbial counts
on products leaving the cooler were far below the
accepted normal levels in vegetable freezing plants.
• Samples of snap beans and lima beans from the prototype
unit were evaluated for taste and texture, and were
judged either as equal or superior in flavor and
texture to those processed in a conventional blancher-
cooler,
RECOMMENDATIONS
• The design changes recommended for brussels sprouts,
broccoli, and caulifl'ower need to be incorporated and
tested under actual plant conditions on a modified
prototype. ,
• The prototype unit should be tested in a canning plant
without the cooling section. The performance data
indicated that the blancher condensate be evaluated as
a potential canning brine.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
VIBRATORY SPIRAL BLANCHER-COOLER
Executive Summary
6. PERFORMING ORGANIZATION CODE
7J*t™
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