Computers chem. Engng, Vol. 18, Suppl., pp. S597-S601, 1994 Printed in Great Britain. All rights reserved
0098-1354/94 $6.00+0.00 Copyright © 1993 Pergamon Press Ltd
CAD FOR CLEANER PRODUCTION IN FOOD PROCESSING
AGNES BALINT
Department of Chemical Technology, Technical University of Budapest
1521 Budapest, Hungary
ABSTRACT
Whey processing alternatives were investigated with the help of Computer Aided Design. Mass and energy balances were calculated, units were sized, economic analyzes was conducted. With the help of profatibility methods the best alternatives were suggested.
KEYWORDS
Computer Aided Design, flowsheeting, waste processing, whey.
INDRODUCTI ON
Computer Aided Design has become an essential tool for engineering problem solving in the chemical process industries. The food industry must followthe trend to greater computerization as means of increasing productivity and minimizing waste.
Dairy processing comprises a large portion of food processing industry. Cheese is a major dairy product, whey is a byproduct of the cheese manufacturing process, with about 1 kilograms of whey produced per kilogram cheese.
WHEY PROCESS ALTERNATIVES
Whey is a potent waste in terms of its polluting strength with BOD of 45 000 mg/l, which compares wi th 300 mg/l for human sewage sent to waste treatment facilities (Jelen, 1919). The high BOD content makes disposal expensive.
Fluid whey directly from cheese production generally contains 6.5 w/w % solids. The uusual composition of whey is 0.80 % protein, 4.80 % carbohydrate, 0.25 % fat, 0.65 % ash, 93.5 % water. Lactose makes up the bulk of the sollds, comprising about 10 % of the dry matter. On the other hand, the protein content only avarages 11.5-18 % of
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dry matter but is nutritionally and functionally the most valuable part of whey components. Minerals are the fourth large component of whey and are the major factor hindering the development of new consumer products from whey (Allum, 1980 ). Whey can be processed into a variety of products e.g. Condensed Whey, Whey Protein Concentrate (WPC), Lactose, Demineralised Whey, Reduced Lactose Whey, Hydrolized Whey Syrup, Ethanol and other Fermentation Products.
Many alternatives for the disposal of whey exist, but determining the most profitable alternative for a particular situation from the myriad of existing options can be difficult task. The Computer Aided Design provides the engineer with the modelling these alternative processes and comparing them economically.
In an depth study different process combinations were conducted using PPDPACK (Preliminary Process. Design Package) to determine which whey process alternatives provide the best economic return. About PPDPACK see Hsu, 1984, Moyer, 1987, Havlik, 1989, Balint, 1989.
WPC is made with the operation steps of ultrafilteration, evaporization and drying (Process P1). Utilization of the permeate has been a major problem for WPC producers, as the permeate still has a high BOD (about 27 500 mg/l).
Utilization of permeate was investigated. In some of the alternatives products were made without chemical modification of the solid content of the whey only with concentration and powdering, in other processes with physical and chemical modifications with fermentation, ion-exchange and hydrolysis.
Process P2 produces with the help of reverse osmosis and evaporization a permate product called condensed permeate syrup. This product can be used as a lactose source for a wide variety of fermentations or as a feedstock for crystalline lactose production. Process P3 uses a fermentation system to produce ethanol from the permeate. The next process P4 is just a dried version of process P2. It is used as whey solids in a variety of dairy and baked products. Obviously crystalline lactose can be produced from the lactose rich permeate, and process for doing so constitutes process PS. Crystalline lactose is used for encapsulation of drugs in the pharmaceutical industry and for vitamins and other pill type products. The last permeate utilizing process is process P6, hydrolyzed permeate syrup. In this process, the lactose is hydrolyzed using enzyme columns to produce glucose and galactose, increasing the sweetness of the product significantly. Hydrolized permeate syrup has been used as a sweetener in some drinks, but more often is used in dry form in the baking industry.
The technologies were modelled at 5 different flowrates it means that 6*5 alternatives were investigated. Figure 1 shows the total capital investment, Figure 2 shows the annual operating cost (1 US $ = 80 Fts), Figure 3 shows the energy demand, of the processes.
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Total Capital Investment MFt 700r----------------------------------------------.
600 ··P4···
P5
600 .P.2 ............ .
PI
400 .. P~.
Pl
300
200
100
OL-------L-------L-----~------~------~~----~
o 100 200 300 400 500 600
Flowrate 1000 kg/day
Fig.l. Processes Total Capital Investment
Annual Operating Cost MFt
300.---------------------------------------------.
260 ............................................................................................................ .
200
160
100
60
P4 P5
P2
PI P3 .................. .
Pl
O~~----~------~----~~------L-------L-----~
o 100 200 300 400 500 600
Flowrate 1000 kg/day
Fig.2. Processes Annual Operating Cost
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Electrical Energy 1000 MWh/year
3
2.6
2
1.6
1
Natural Gas 1000 m3/year
360
300
260
200
160
100
60
0
Steam Demand 1000 tlyear
26
20
16
10
6
o
.P1 ~P2 C]P3 ~P4
....... ....... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... .......... :::::::::: .......... .......... .......... .......... .......... .......... ..........
'::::1 P6
Fig. 3. P1-P6 Processes Energy Uemand
OP6
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RESULTS
According to the two most important economic measures IRR ( Internal Rate of Return on Investment) and ACF (Annual Cash Flow) process P3 ( ethanol fermentation) seems to be the best alternative at any flowrate. This process has the highest IRR and ACF values, the smallest capital investment and the operating cost. Making laktose spray (P4) or edible lactose from permeate (P5) yield the worst IRR value, these processes aren't economical alternatives.
The effect of the capacity was investigated too. All technologies have a lower capacity limit that means production under this scale are relatively uneconomical. This value was found about 50 000 kg/day. Much of whey disposed comes from smaller cheese manufactures that do not have the available financial resources to produce whey byproducts. The solution should be the corporation of the different small cheese manufactures.
REFERENCES
Allum, D. : Whey -The International Scene. Journal of the Society of Dairy Tech., 33, 2, 1980. p.59-66.
Balint, A. , Okos, M. R. : Teaching Manual to PPDPACK Purdue University, West Lafayette, IN. 1989.
Havlik, S. : Food Process Modelling M. Sc. Thesis. Purdue University, IN. 1989.
Hsu, S. Y. : A Multilevel Approach for Preliminary Process Development. Ph. D.Thesis,Purdue University, IN. 1984.
Jelen, P. : Industrial Whey Processing Technology: An overview. J.Agric. Food Chem., 27, 4, 1979. p.658-661
Moyer,P.S. Computer Aided Food Process DeSign. M. Sc. Thesis, Purdue University, West Lafayette, IN. 1987.
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