Energy Audits in Meat Processing Operations

ENERGY AUDlTS IN MEAT PROCESSING OP€RATlONS

by Jay S. Marks and Martin R. Okos*

Nearly everyone at this meeting would be classified Btu’s per pound. The tenn “typical plant” illustrates as an expert. Generally that would be considered one of the problems that currently exist. Much of the good. However, the difficulty comes when you talk work in the past has had to deal with overall aver- to experts in the energy field. If you pick a dozen ex- ages for plants, or with overall industry averages. A perts in energy and ask about the level of the current limited amount of energy data has been available on energy crisis, you will get twelve different answers. specific products or on specific unit operations. This Despite this uncertainty, you would probably all agree situation led to Piirdue’s interest in energy usage in that the energy situation is important to your group. meat packing. The Agricultural Engineering depart- In dealing with food production, energy is a signifi- ment is conducting a project for the Department of cant factor, and will become more so. Energy, involving monitoring of two typical meat plants on a unit by unit basis. From these data can With the rising energy costs, the experts will gen- be compiled energy usage on a product by product erally agree on two facts: 1. energy costs are going to basis also. This will be desirable basic information, go up and 2. spot problems will be in certain areas and relatively easy to adjust for specific plant types where energy sources will be in short supply. and sizes. Plant Sizes Vary The procedure used for this project was to gather all data directly from in-plant measurements. The ini- The meat packing industry should be very con- tial step was to review the actual plant operation steps cerned about any potential energy shortage. Approxi- to estimate energy flow rates. Energy balances were mately 90 trillion Btu’s are used annually in this calculated from these data to check the estimates. country in meat processing, in order to produce 31 From these estimates, the types and sizes of metering billion pounds of meat product. One difficulty in and monitoring equipment were selected. evaluating these data is the great diversity of plant sizes and types. For instance, 2/3 of the plants have Problems developed when the initial metering in- less than 20 employees and produce about 4% of the stallations were made. Actual measurements showed total U.S. meat products. Only 6% of the plants employ the original estimates to be in error by as much as over 250 people each, but the output of these plants 300%. Unfortunately, this variance indicates that stand- make up 60% of the total production, ard engineering techniques cannot be safely used for accurate estimates of energy flows in meat plants. Type of Products Vary Too many variables and too many unknowns are pres- ent. These estimates are adequate for equipment se- In addition to a great variety of plant sizes, con- lection, however. siderable variance in the type of products are found. Estimates of energy usage run from 750 Btu’s per Significant problems were encountered with the pound for fresh cuts of meat to as much as 12,000 original metering equipment. If individual plants or Btu’s for sausage. This great diversity still adds up to individual researchers start a metering program, this a high energy use for meat packing. This in turn will likely be a difficult area. means much expense, and much difficulty if the need- The original turbine meters selected were adver- ed energy cannot be obtained. tized and sold for use with steam. However, typical operating life in the plants was on the order of one “T y p iwZ Plants” Stud iecl hour. Condensate in the steam lines would destroy Typical plants use an average of 1,ooO to 5,000 the turbines almost immediately. Vortex shedding meters were selected to replace the turbine meters. “J. MARKS The measurement equipment found to be satisfac- Department of Agricultural Engineering, Purtlire tory for the Purdue study included Neptune/Eastech Uniuersity, \Vest Lafuyette, IN 47907 vortex shedding flow meters for gas and for steam. For water, Mead turbine flow meters: were selected Reciprocal Meat Conference Proceedings, Volume 32, 1979. where continuous monitoring was required. In many

- 50- AMERICAN MEAT SCIENCE ASSOCIATION cases, Rockwell totalizing meters were satisfactory TABLE 1 where daily total water flow would suffice. These meters were also used on glycol measurement for refrigeration streams. Temperatures were measured with . RTD's (resistance temperature devices). All of the SI'UN. III.CF.II, Sl:Al.ll inforvation was transmitted by wire to a central mul- U tXA 1R tiplexer. The multiplexer converted the data from I.VISCER,\TE analog to digital form, and fed the data to a small 81'1.1I. IIACKS Atill computer. 1'UI.I. IARD 111 1\11 lAlll E The data collection required an exceptional amount 8II~IUI.K of cooperation from the individual plants. The exten- CHILL CARCASS sive wiring installation caused interference with main- tenance and production schedules. In addition, the in- KILL FLOOR BASIS: 1.0 POUND CHILLED CARCASS stallation had to fit meat plant sanitation require- ments.

Abut 40% of the vortex shedding meters were in- sanitation. In some cases, sanitation covers more than operative as received. This was unfortunately typi- one processing activity. This is because these activi- cal of much of the instrumentation purchased for this ties take place in the same general area, and the project. Four of the five multiplex units did not func- sanitation usage covers that whole physical area. tion properly when first delivered. Generally the mi- Steam is a major energy factor on the kill floor, pri- crocomputers functioned well. marily due to use of steam to heat the scald tank. The The use of microcomputers was not necessary to large gas use shown is for the direct flame singeing the data collection, but greatly extended the amount used. As expected, refrigeration usage is high due to of data that could be obtained. the carcass chilling. Once the full instrumentation was available, stu- Figure 1 is the flow chart for bacon processing by dents from Purdue spent the summer in the plants the batch method. supervising the installation of the equipment and This flow chart is typical of these drawn for each calibrating the system. process. Each step in the process is laid out. Then for Also during this time the electrical data were col- each step the steam, electricity, gas, water and refrig- lected. Electrical measurements were made with port- eration flow in and out were totaled. These totals able Amprobe recorders. Many more points could be were then used to generate the summary tables shown measured this way than with fixed installations. Many in this paper. Table 2 is the energy use summary table typical motors in the plant were selected and moni- for batch processing of bacon. tored through full operating cycles. Note the large amount of gas used for smoking and All of the other data, which was fed to the micro- refrigeration used for chilling. A considerable amount computer, were collected over a several month pe- of steam is used for sanitation in this process. riod. The microcomputer operated unattended, re- Frankfurters involved a more extensive evaluation cording processed data onto a floppy disc. The data than bacon. The flow chart in Figure 2 demonstrates could then be picked up on a weekly basis. this fact. In a smoke house there are many energy The various problems encountered with the measurement equipment did not prevent obtaining high quality data, but they did make obtaining these data relatively difficult. The data for the individual unit operations were 18 used to calculate the energy usage totals for process SH 214 steps. For example, Table 1 shows the information 0.4 for the kill floor. 11 The data in Table 1 have been grouped into sec- I.! tions of "stun" through "chill." Note that the steam BACON usage is divided into two categories: process and BASIS: 1.0 POUND BACON PACKED -511 - AMERICAN MEAT SCIENCE ASSOCIATION BACON PROCESSING

BELLIES 1.04 X

239.4 BTU REF: CURE AREA 5.28 WH

- 124. I BTU AIR b 274.3 BTU GAS * SMOKl NG f BTU AIR 13.97 W H c

0.11 WH * HOT SKIN

\I * 0.07 # SKIN 66.9 8TU REF.-

~ BRINE CHILL 1.37 WH .

"*0.80 BTu WH REF' e-J BLAST CHILL

10.3 BTU REF. 1.14 WH

80.9 BTU REF.- 21.2 WH PACKAGING c

PACKAGED BACON 1.00 #

FIGURE 1 AMERICAN MEAT SCIENCE ASSOCIATION flows to measure. Table 3 shows the results of these Table 6 gives comparable data for inedible trim measurements. rendering. Huge amounts of energy are uscd in this process. The cooking step uses very large amounts of Approximately 25 percent more energy is used per steam. In this process, the sanitation needs are high pound of frankfurters as compared to bacon. Frank- also. Steam is used at high levels for wash-down hot furters require more steam for sanitation and more water. refrigeration, but slightly less gas. It is relatively ex- pensive to produce frankfurters in terms of energy Because preliminary estimates indicated that sani- consump tion. tation energy needs would be significant, particular attention was given to this area. Plant personnel gave At the second plant, the frankfurter production was guidance as to which wash-down stations were typi- done in a continuous process. Data from this opera- cal. The wash-down stations were of the steam-water tion gave a comparison to the batch process. Table 4 mix type. Both steam and water on the selected sta- shows the data. tions were metered, generally with totalizing meters. The major difference noted in the comparison be- This information enabled calculating the average tween batch and continuous frankfurter production wash-down energy usage. The students in the plant was that much more energy was used for continuous during the summer verified that the selected stations production. The increased energy usage was the trade- were representative. off for reduced labor usage. This type of trade-off Hair hydrolyzing also uses large quantities of en- must be carefully evaluated, especially in considera- ergy, as shown in Table 7. This is not surprising, since tion of a new plant. Research is needed on methods hair is a very low density product. Energy figures on of operating labor-efficient processes without greatly the basis of Btu's per pound of dry hair are leveraged increasing energy consumption. by the low density. Various rendering processes were examined. It was The next table deals with process efficiencies. A found that rendering was a very high consumer of problem arises when efficiency is discussed. Several energy. Table 5 shows data for edible rendering. As shown in Table 5, very large quantities of steam are used in the lard processing in edible rendering. TABLE 5 This is the major energy usage in the process. Other I 1 forms of energy are used at considerably lower levels. OPERATION

CRlND AND LOAD 12.h TABLE 3 COOK

~ COOK I LOAD AND SANITATION __.sr PROCESS CENTRIFUCE BTU .__ SEPARATE AND 77 t-- STORAGE SANITATION

EDIBLE RENDERING SMl1Il: 4.6 BASIS: 1.0 POUND OF LARD

COOL ANU CII1I.L 16

PPEL AND PI\(.K 21 1.0 ... TABLE 6 F RANKF U RTER PROCESS1 NG BASIS: 1.0 POUND FRANKS PACKED

PREBREAK 48 TABLE 4 CWK 96

1 I3 PERCOLATION I FXPlIIbR(CW) 1 '4

__ _- CONTINUOUS VS. BATCH FRANKFURTER PRODUCTION INEDIBLE RENDERING (INEDIBLE TRIM) BASIS: 1.0 POUND FRANKS PACKED BASIS: 1.0 POUND GREASE (1.43 POUNDS CRAX)

- 53 - AMERICAN MEAT SCIENCE ASSOCIATION FRANKFURTER PROCESSING

1.98 WH RAW MEATS 69.4 BTU- REF.4 COOLER A ------r------1I I I I lo." # I I m I I 1.78 WH GRIND I I I I I I I I I 2.16 WH SCALE I 1 I I I 0.38 rY INGR +3O0F . 323.7 BTU REF4 I I 76.8 BTU ST 250°F, *OOoF-13.2 BTU COND. I 7.26 WH - 7 0.81 WH BLEND -34.8 BTU LOSS I - I I I I 1.10 # 6OoF I -1 I I I I 16.92 W H F EMULSIFY I I I I 0.02 # CASINGS I I =.65*F I I I I 0.94 WH w STUFF I I I I I I 1700~ I

FIGURE 2 AMERICAN MEAT SCIENCE ASSOCIATION FRANKFURTER PROCESSING ( Cont.)

97 DE, 100-175 DB 124 BTU AIR t 79 % 6.36 WH - 80-'30w!- 317.7 BTU AIR 183.7 BTU GAS2= SMOKE e 0.0039 # COND. 4.58 BTU ST TOOF* loooF t 1.74 # WATER

1.02# 8OoF

WH LINK COOLER 42.4 BTU7 REF I

I I I4.3t3 WH - PACKAGE I L ------I

FRANKS 7 i I.OO#

. J 2.49 U WATER OVERALL FRANK 204.6 BTU ST. - PROCESSING SANITATION -c AMERICAN MEAT SCIENCE ASSOCIATION

definitions for efficiency can legitimately be used, and next step was then to evaluate various methods of en- each may be useful for different purposes. Efficiency ergy conservation. Basically these fall into two cate- in this case is chosen to compare energy that actually gories: 1. Recovery of energy now being lost and 2. goes into the product to the energy supplied to that Process or equipment modification to reduce energy processing operation. This definition is useful in eval- usage. uating plant efficiency, but will give low numbers. Hog singeing gives a good example of where en- For example, most of the energy supplied to a smoke ergy recovery can be effective. Most of the waste heat house is vented to the atmosphere. However, this goes out the vent stack. The quantity of heat dnd venting is used as one means of controlling the hu- temperature of the exhaust are suitable for recovery midity in the smoke house. using an air to water heat exchanger. The recovered The definition of energy used here gives an insight heat can be used for several purposes. Hot water for into the fact that the potential for energy reduction clean up is an obvious choice. Another potential use is large. The numbers in Table 8 demonstrate this. is to supply hot water for the scald tank. The physical However, these numbers are not representative of the location of the scald tank is usually close to the singe- actual degree of potential. In many cases, the best ing operation. available technology will not give anywhere near 1OG% efficiency. Recovery of heat from the smoke house exhaust is a similar opportunity. Nearly any process that dis- One important consideration in evaluating the data charges waste heat can be examined in terms of po- in Table 8 is that the efficiencies are based on energy tential heat recovery. cklivered to the process. This does not take into ac- count that steam generating efficiency is usually be- A heat pump is one means of transferring heat from low 85%.Nor are the losses in a typical distribution a waste stream to a process use. Three methods of system included. producing hot water for sanitation were evaluated. Table 9 shows the results. The basic information collected described what energy is being used, and what potentials exist. The Refrigeration equipment in a meat processing plant usually discharges the heat to the atmosphere. Recov- ering this heat is an efficient means of providing hot TABLE 7 sanitation water. A heat pump is efficient for 140"F, but its efficiency decreases rapidly as water temperature increases. WAI'EK PIJUNUS

. An example of alternate process equipment is modification of a smoke house. Table 10 shows the total energy used for a conventional batch house as measured by the Purdue project, energy calculated for a closed loop batch house, and energy calculated for

2.1 an "ideal" continuous system. This last system would . use warm water from the water shower to heat in- INEDIBLE RENDERING (HAIR) coming frankfurters and a heat pump for additional BASIS: 1.0 POUND DRIED HYDROLYZED HAIR heat recovery. This may not be a feasible system, but demonstrates the potential that should exist. TABLE 8

TABLE 9 ENERGY ENEKCY SUPPLIED USED I EFFICIENCY ...... HI.U/LR [I r1'lI.H

HESHOD PO'? 310 bJ 202 ~r lr? n.illon.; ~ --. - ~. ._ . 1,itm 07 6% IIEFRIGERATION 590 132 22% HEAT KECOVEKY $2.81 1.1RO 162 121 IIEAT PUMP b,HOO hlu 1 oz (7S°F sO,Ircc.) 5 I. I(, 11.700 670 6Z S'L'IA\l BOII.I:R $5.110 9,oflo 1,288 14% ~__...... HOT WATER COSTS PROCESSING ENERGY EFFICIENCIES (140DF1Water) -56- AMERICAN MEAT SCIENCE ASSOCIATION

TABLE 10 to skinning. Many more variables must of course be considered. PER POUND OF PRODUCT TYPE BTU FINAL A major result of the Purdue study is a determina- CONVEN'TIONAL 342 -1tion of those process areas where the most potential CI.OSED I.00P 194 exists for energy conservation and reduction. Much of the basic data are applicable to various sized and IUWL 131 type plants. These data then will reduce the amount SMOKE HOUSE COMPARISONS of actual measurement that must be done at an individual plant. In addition, these data will signifi- cantly reduce the potential for error in selecting and Another example of a modified process is skinning sizing measuring equipment. versus scalding of pork. The Purdue Animal Science Department has estimated a 98% reduction in energy Each plant will have better tools to evaluate their for this step by changing from scalding and singeing own savings potential.

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