ECONOMICAL USE OF FUEL IN CREAMERIES. 31 



a greater economy may be obtained by using a gas engine or an 

 electric motor that can be put into or out of service as required. 



The relative cost of coal, gasoline', or electricity delivered at the 

 factory must also be taken into account in selecting the kind of 

 power best suited for any particular plant. In some cases the factory 

 is a considerable distance from the railroad, and the inconvenience 

 and expense of getting coal to the plant may be such as to prohibit 

 the use of a steam engine. In other cases the cost of electricity may 

 be so small as to make its use profitable. By utilizing the heat in the 

 jacket water and exhaust gases of internal-combustion engines it is 

 possible in some plants to produce the necessary quantity of hot 

 water for heating, or the heat may be used to supplement that of a 

 steam boiler, thus reducing the size of the boiler. A typical arrange- 

 ment of such an equipment is illustrated in figure 9. In short, there 

 is such a wide variation in the operating conditions of creameries 

 throughout the country that it is impracticable to state in general 

 just which form of power is the most economical, as each case re- 

 quires a special study. 



UTILIZING THE EXHAUST STEAM. 



It should be the aim of any one in charge of a steam plant to 

 utilize -as much of the heat energy contained in the fuel as practic- 

 able, and there are few classes of steam plants that offer more varied 

 opportunities for the utilization of exhaust steam from the engine, 

 pumps, and other steam-driven machinery than those used in the 

 dairy industry. In plants in which steam is generated for power 

 purposes only, even with the best possible apparatus- and arrange- 

 ment, only a small portion of the heat in the coal is utilized. In the 

 dairy industry, however, where much low-temperature heating is re- 

 quired which can be accomplished through the use of exhaust steam, 

 even the smallest plants with little or no extra expense can be made 

 much more efficient than the most modern steam plant when used only 

 for the generation of power. There are dairy plants, however, that are 

 taking advantage of their opportunities to use the heat available in 

 the exhaust steam. 



In the, dairy industry large quantities of hot water are required 

 for washing apparatus and utensils, pasteurizing, boiler feed water, 

 and other puf poses around the plant. The heating is done at present 

 for the most part by live steam from the boiler, whereas the large 

 amount of exhaust steam going to waste might be used for the pur- 

 pose. 



Exhaust steam at atmospheric pressure contains between 85 and 

 90 per cent of the heat of the live steam at 70 pounds' gauge pressure. 



