Agroindustrial project analysi

COSTS OF ALTERNATIVE TECHNOLOGY 163Capacity1977 operating cost(pounds ofDryer raw 1977 Per poundvolume material installed of raw(cubic feet) daily) cost Daily material1004001,5006,00013,49023,51065.30161.000.0440.027800 12,000 45,000 290.00 0.024Capacity estimates are derived by the following assumptions:* Fifty 5-square-foot trays per 100 cubic feet, or 750 poundsper 100 feet* Loading of 3 pounds of raw material per square foot, or 15pounds per tray* Raw material contains 75 percent moisture (generally speaking,meat products contain 55-81 percent moisture, vegetablescontain 75-90 percent moisture, and fruits contain 80-95 percentmoisture), and most of this moisture is removed duringdrying at an overall drying rate of 0.2 pounds of water evaporatedper square foot hourly, or 1 pound per tray hourly* Seven hundred and fifty pounds of raw material at 75 percentmoisture contain 560 pounds of water and, at 1 pound pertray hourly,, a 1oo-cubic-foot dryer holding fifty trays will take11 hours for drying and 0.5 hour for loading and unloading* Two 12-hour cycles daily* "Raw material" refers to prepared material ready for drying.Porter 4 found that f.o.b. (free-on-board) costs of cabinet dryersin 1970 were $12 per cubic foot (dryers larger than 300 cubicfeet) to $40 per cubic foot (dryers with 100 cubic feet). Costs includedaluminized steel housing with 4 inches of insulation, circulatingfan, and an air heater. Control instruments added $200-800,trays cost $2-4 per square foot, and trucks or racks cost $200-400.Installed cost is 50-100 percent over f.o.b. cost. According to thesedata, the following tabulation can be made (1970 installed cost iscalculated at 50 percent over f.o.b.):4. Porter, "Gas-Solid Systems," pp. 20-1 to 20-121.