12 



BULLETIN 1£l, U. S. DEPARTMENT' OP AGRICULTURE. 



sufficient distance between the fuel bed and the boiler shell to allow 

 for their complete expansion and ignition before coming into con- 

 tact with the boiler shell. Soft coal usually contains a large pro- 

 portion of volatile matter; consequently it needs considerably more 

 space between the fuel bed and the boiler than anthracite. 



The radiation losses from' the sides* of the furnace and combus- 

 tion chamber are comparatively small in any well-set boiler and as 

 the combustible gases rise a considerable distance before losing any 

 appreciable heat the, distance between the grate bars and the boiler 

 shell should be increased over that generally used in setting boilers. 

 This dimension depends on the kind of coal burned, the rate of burn- 

 ing, and upon other factors, all of which should be known in order 



Table 2. — Dimensions of setthrgs for 







a 

 3 



3 



Walls. 





Spacing shell 



to— 









go 



^ 



Front. 

















. - 





wis 















^ 



"g 



^ 





o 



o 

 cd 



to 



>- a 



CD'r- 



o 2 



CD +3 



yi cd 



■9 



CD 



s 



1 



M 



o 



C3 







o 



a 



a 

 to 



2 



o 



a 



+3 



'8 



CD 



-n 

 § 



p 



CD 



o 



a 

 P 



M 

 o 



C3 



1 



03 



CD 

 S 



CD 

 & 

 O 



a 



CD 

 H 



CD 

 "S 



CD 



■3 



CJ 



.3 



"3 

 % 



CD 



3 



*E 

 o 



<B 



a 



si 



u . 



c 





 OsA 



ii % 



_ o 



A 



" 



M" 



ffl 



o 



h 



ffl 



M 



5 



K 



CO 



O 



a) 



A 



B 





c 



D 



Di 



E 



F 



H 



I 



J 



K 



L 



30 



8 



12.2 



21 



9 



13 



13 



84 



50 



16 



9 



28 



2 



32 



8 



12.5 



21 



9 



13 



13 



86 



50 



16 



9 



28 



2 



32 



10 



15.6 



21 



9 



13 



13 



86 



50 



16 



9 



28 



2 



36 



8 



15.9 



21 



9 



13 



17 



94 



54 



16 



9 



30 



3 



30 



10 



19.8 



21 



9 



13 



17 



94 



54 



16 



9 



30 



3 



36 



12 



23.7 



21 



9 



13 



17 



94 



54 



16 



9 



30 



3 



36 



14 



27.6 



21 



9 



13 



17 



94 



54 



16 



9 



30 



3 



36 



16 



31.5 



21 



9 



13 



17 



94 



54 



16 



9 



30 



3 



40 



10 



26.6 



25 



9 



17 



17 



100 



56 



18 



10 



32 



3 



40 



12 



32.1 



25 



9 



17 



17 



100 



56 



18 



10 



32 



3 



40 



14 



37.4 



25 



9 



17 



17 



100 



56 



18 



10 



32 



3 



40 



16 



42.5 



25 



9 



17 



17 



100 



56 



18 



10 



32 



3 



42 



12 



33.4 



25 



9 



17 



17 



102 



56 



18 



10 



32 



3 



42 



14 



39.2 



25 



9 



17 



17 



102 



56 



18 



10 



32 



3 



42 



16 



44.6 



25 



9 



17 



17 



102 



56 



18 



10 



. 32 



3 



44 



12 



36.7 



25 



13 



17 



21 



106 



58 



18 



10 



32 



4 



44 



14 



43.0 



25 



13 



17 



21 



106 



58 



18 



10 



32 



4 



44 



16 



49.0 



25 



13 



17 



21 



106 



58 



18 



10 



32 



4 



44 



18 



55.0 



25 



13 



17 



21 



106 



58 



18 



10 



32 



4 



48 



12 



43.0 



25 



17 



21 



21 



112 



60 



18 



10 



34 



4 



48 



14 



50.2 



25 



17 



21 



21 



112 



60 



18 



10 



34 



4 



•48 



16 



57.3 



25 



17 



21 



21 



112 



60 



18 



10 



34 



4 



48 



is 



64.8 



25 



17 



21 



21 



112 



60 



18 



10 



34 



4 



54 



12 



52.7 



29 



17 



21 



25 



122 



64 



20 



12 



36 



4 



54 



14 



61.8 



29 



17 



21 



25 



122 



64 



20 



12 



30 



4 



54 



16 



70. 5 



29 



17 



21 



25 



122 



64 



20 



12 



36 



4 



54 



18 



79.3 



29 



17 



21 



25 



122 



64 



20 



12 



36 



4 



60 



12 



62.7 



29 



21 



25 



25 



128 



64 



24 



12 



36 



4 



60 



14 



73.0 



29 



21 



25 



25 



126 



62 



24 



12 



36 



4 



60 



16 



83.3 



29 



21 



25 



25 



126 



62 



24 



12 



36 



4 



60 



is 



g3.6 



29 



21 



25 



25 



126 



62 



24 



12 



36 



4 



60 



20 



104.8 



29 



21 



25 



25 



126 



62 



24 



12 



36 



4 



