ETHYL ALCOHOL FROM WOOD WASTE. 67 



POWER REQUIREMENTS. 



The steam load of the plant will be distributed about as follows : 



Per cent. 



Pumps — boiler, fire, general water supply, beer, alcohol 20 



Digesters 30 



Hogs and shredders 20 



General power for driving conveyors, digesters, etc 15 



Distillation and rectification, (including all exhaust steam not used for heating 



boiler- feed and extraction water) 15 



100 



A large supply of pure, cool water is also necessary. It should be 

 pure for boiler and extraction purposes, and cool for use in cooling 

 and condensing. The disposal of the beer-still slop requires atten- 

 tion, because it contains a large amount of pentose carbohydrate and 

 dead yeast; the latter of which is highly nitrogenous. However, 

 the slop does not putrefy on standing and will maintain a nearly 

 sterile condition for a long time. 



COSTS. 



As outlined before, the commercial production of alcohol by this 

 process, with two exceptions, has not been a success. If such a 

 yield is assumed, however, as that obtained at the Forest Products 

 Laboratory, and if the necessary manufacturing losses are allowed, 

 as for instance, the extraction loss in the sludge of the settled juice, 

 and the distillation and rectification losses (which, combined, should 

 not be over 20 per cent of the total product), a yield of about 20 

 gallons a dry ton is obtained. Assuming this yield, and a location 

 in which the supply of waste will be uniform and constant for a 

 period of 20 years, and in which plenty of good water may be had, 

 with a supply of sulphuric acid and lime reasonably nearby, the cost 

 of a gallon of 190-proof alcohol from wood in a properly designed and 

 constructed plant having a capacity of 2,500 or 3,000 gallons a day, 

 is estimated to be as follows: 



Yeast nutrients $0. 015 to $0. 020 



Repairs and materials (exclusive of fuel and wood). 030 to . 040 



Labor 015 to .030 



Wood and fuel 020 to .020 



Interest at 7 per cent 019 to . 020 



Depreciation at 10 per cent 023 to . 035 



Overhead, taxes, etc. . 015 to . 030 



Total. 137 to .195 



In the above table wood has been valued at 40 cents a cord, 1,800 

 pounds of dry wood being considered to be a cord. This wood should 

 consist of sawdust and hogged refuse, but should not contain over 

 10 per cent of bark, as the yield of sugars and alcohol from bark is 



