4-1 



BULLETIN" 74*7, U. S. DEPARTMENT OF AGRICULTURE. 



largest and one that can be reduced only slightly by careful firing 

 and by stopping all air leaks in the setting, firing doors, doorframes, 

 and other places. Even in the case of a well constructed and main- 

 tained boiler setting, 10 pounds of coal per horsepower capacity of 

 boiler will be required for raising steam. With poorly constructed 

 and maintained settings this quantity of coal will be exceeded. 

 . The loss of small particles of unburned coal which fall through the 

 openings in the grate bars and are removed with the ashes may be 

 reduced by more careful firing. The coal is broken up and falls 

 through into the ash pit on account of stirring the fuel bed with the 

 firing tools. If proper attention is given to the fire it is not neces- 

 sary to stir up the fuel bed, and the percentage of unburned coal in 

 the ashes will thus be reduced. While it is impracticable to eliminate 

 this loss entirely, careful firing will greatly reduce it. 



AgAT KZ QUmED TO FIAISE ST^AM* £27Z 

 LOST IN AS.HSS . /K 



r tosrfl-/?jcM T/ow in Boiuen /toon. *t.z% 



| LOST THROUO.H Inf coMPL gTF co»tmi°s T roN ■, 1% 



L.I3SS IN 'CHIMNCY TOMANT.+IIV DKAFT. /P/;* 



£OS3 DUE TO HSAT/IVG / TO/ST-z y/Tf J/VCOAL.. 1% 



trans mission f-ftOM £nGit/1£ TO MACHIHenY^O LZ % 



HCAT C ONSUMED BY £/YGj/fy£ IN USEFUL WORK, SJ7. 



HCATINC* mtl-K FPU SEPARATION. I.SZ 

 HCATI/VO. STn/TTe/t MIL K , O.^ f 



Fig. 14. 



ATAT/NSt WAS* WMTgB ■ Jl** X 

 STSAItlMG. AND QltYINO, CANS,ZJ>T. 



hsat RE-ra AiNmainiexH/tusT.&xx 

 l HGAT nCTVKNep T OBOILSK in reeo wATens.an 



—Graphic illustration of the possible distribution of heat energy in a creamery 

 making 500,000 pounds of butter annually from pasteurized cream. 



The quantity of heat radiated from the setting, uptakes, breeching, 

 and from the exposed positions of the boiler itself depends, of course, 

 on the arrangement of the particular plant, and while it is given in 

 the table at 4 per cent, it is often considerably more. While some 

 loss by radiation is unavoidable, the greater portion can be prevented 

 through insulating the exposed surfaces. Efficient insulation not 

 only conserves the heat but reduces the temperature in the boiler 

 room, increases the draft, and when applied to iron surfaces prolongs 

 their life. The insulation of the uptake and breeching may be effected 

 by applying asbestos or magnesia blocks held in position and covered 

 with a half-inch coat of asbestos or magnesia plaster. The walls of 

 the boiler setting should be made amply thick to begin with, and 

 should have a 2-inch space constructed in the wall. The United 

 States Bureau of Mines, through exhaustive experiments, has proved 

 that a wall with an air space will lose more heat than one of the same 

 thickness constructed of solid masonry. The air space, however, is 

 valuable in reducing the liability to crack. It should be filled with 



