VEGETABLE AND FRUIT DEHYDRATION 



19 



erating difficulties due to lack of equipment and limited floor space. 

 Dehydration plants should be balanced units, and the costs of various 

 parts will be low or high in accordance with the circumstances affect- 

 ing each particular machine, operation, or floor-space requirement. 



These costs must be considered as only very rough estimates since 

 they cannot possibly include all items. Even a plant that has been 

 completely engineered before construction may present the owner 

 with additional cost items before it is finished. Conditions vary 

 throughout the country, and these variations materially affect any 

 attempt to arrive at generalizations regarding costs. 



Handling Capacities and Utility Requirements 



The capacities per unit of time at various points along the proc- 

 essing line of a 50-ton plant are shown in table 4. Data are given for 

 seven vegetables important in the present program. Such tables are 

 of assistance in estimating labor requirements and equipment sizes for 

 each operation. 



Facilities must be available to provide approximately the quantities 

 of heat, power, and water indicated in table 5. The figures in this 

 table allow for the differences in consumption of utilities under various 

 operating conditions. The indicated demand load for electric power 

 is really total connected load. The average operating load will usually 

 be smaller. 



Table 5. 



Approximate utility requirements for dehydration plants of various 



sizes 



Utility and application 



Requirements per hour for plant of— 



100-ton 



50-ton 



25-ton 



Water: 



Potatoes and sweetpotatoes gallons-. 



Carrots, beets, rutabagas, and onions do 



Cabbage do 



Electricity: 



Demand load kilowatts. _ 



Fuel: 



Dehydrator: 



Direct heat _. _ . .millions B. t. u. L. 



10, 000-20, 000 



8, 000-16, 000 



2, 400-4, 000 



150-250 



15-20 



30-50 



20-30 



4-8 



100-200 

 500-700 



5, 000-10, 000 

 4, 000-8, 000 

 1, 200-2, 000 



80-125 



7H-10 



15-25 



10-15 



2-4 



50-100 

 250-350 



2, 500-5, 000 



2, 000-4, 000 



600-1,000 



50-70 

 3^-5 



Indirect heat . do. i 



Steam heat do. 1 



Blancher * and incidental do. 1 



Boiler capacity: 



8-13 

 5-8 

 1-2 



25-50 



Dehydrator do. ' 



125-175 



1 The lower limits of heat requirement and boiler capacity for the dehydrator are considerably larger than 

 needed for some vegetables under good operating conditions. On riced potatoes, for example, the mini- 

 mum heat requirement may be less than two-thirds of that indicated. 



2 Low limit is based on continuous-type blancher. If batch-type blancher is used, the ^blanching steam 

 demand will be higher. 



The quantity of heat required varies widely with different methods 

 of air heating and from one vegetable to another. The necessary size 

 of steam plant, even on the same operating procedure, varies with boiler 

 efficiency and care exercised in avoiding steam waste. The lower 

 limits of heat and steam requirement for the dehydrator are consid- 

 erably higher than the actual operating usage for some vegetables 

 under good operating conditions. They allow a margin of safety 

 adequate to permit full-capacity operation at all times, even under bad- 

 atmospheric conditions. Many operators will not find it necessary to 

 have such a large amount of surplus heating capacity. 



