CHAPTER XXV 

 ECONOMIC OPERATION OF CREAMERY 



Inasmuch as it is impossible within the hmited space of this 

 work to enter upon a detailed discussion of the \'arious principles 

 and practices of operating boilers, engines, mechanical refrig- 

 erators, and other creamery machinery, only a few of the chief 

 factors common to creamery practice and affecting economic 

 operation shall be discussed here. For more complete informa- 

 tion students are referred to works treating specialh' of these 

 phases. 



Firing the Boiler. — Much fuel can be wasted or saved accord- 

 ing to the completeness with which the combustion occurs. 

 This again depends upon the manner of firing, upon the regula- 

 tion of the draught, and upon the kind of boiler. The fire 

 on the grates should never be too thick nor should too much 

 coal be loaded on the fire at any one time. A thin, even fire 

 permits of a more complete combustion than is possible when 

 clinkers and cinders are allowed to accumulate on the bottom of 

 the fire and a heap of unburned coal on top. By this latter 

 method of firing, the grates are likely to be injured. 



To get the most heat from the coal the draught should be 

 regulated. The combustible part of the coal is of two kinds: 

 first, the fixed carbon, and second, the volatile matter. The 

 former is the coke or the part of coal which is seen on the grates 

 as a mass of glowing fire. The latter consists of the gases which 

 pass off when a certain temperature is reached, and which, when 

 mixed with a certain amount of air at a given temperature, will 

 burn. The hea\y black trail of smoke seen rising from chimney's 

 is partially wasted coal. If the grates are choked with a thick 

 fire, no air can pass through, and the volatile parts of coal pass 

 off without being burned. 



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