134 MANAGEMENT OF DAIRY PLANTS 



reduce many fuel losses in the boiler room and often throughout 

 the entire factory. 



Creamery boiler losses in a small creamery are estimated by 

 Bowen 1 as averaging about 50 per cent of the theoretical effi- 

 ciency. For a steam plant operated under most economical 

 conditions the following estimate is furnished: 



Loss due to unconsumed particles of coal falling through grate 2% 



Loss due to incomplete combustion 2% 



Loss due to heat being carried away in stack gases 23% 



Radiation and other losses 8% 



Total boiler losses 35% 



Such losses will further reduce the amount of steam pro- 

 duced from a pound of coal, so instead of having n pounds of 

 steam produced this figure is reduced to 



ii X or 7.15 pounds of steam, which is being finally pro- 

 100 



duced from a pound of coal when considering the second esti- 

 mate. The theoretical efficiency obtained from the coal in this 

 case is 65 per cent. Under the small creamery conditions where 

 we figure on a 50 per cent efficiency the amount of steam pro- 

 duced from a pound of coal is n X -^ = 5-5 pounds. 



100 



Losses of Heat When Converting It Into Mechanical 

 Work. Heat is converted into power through the steam en- 

 gine. The amount of power produced is spoken of in terms of 

 horse power. One horse power corresponds to 33,000 foot 

 pounds 2 per minute; 778 foot pounds correspond to one British 

 thermal unit. The amount of heat therefore required to pro- 

 duce one horse-power hour is equal to 



33,000 X 60 _ 2>545 R T v 



It is estimated that a good engine will require from 15 to 30 



1 Circular 209, B. A. I., 1913. 



2 A foot pound is the power required to raise one pound one foot per minute. 



