456 CHAPTER XXIII 



50 per cent. 75 per cent. 100 



excess. excess. per cent. 



Due to Carbon Carbon dioxide . . 1-70 i -70 i -70 



Due to Hydrogen Water .. .. 0-58 0-58 0-58 



Introduced with, air Water .. .. 0-08 o -10 o-n 



Nitrogen . . . . 6-45 7-51 8 -59 



Oxygen . . . . o -65 o -97 i- -30 



To reduce these figures to a pound of mill bagasse containing 55 per cent, 

 dry matter and 45 per cent, water, all that is necessary is to multiply by 

 O'55 and to add 0-45 Ib. to the water, whence the following results are 

 obtained in terms of a pound of mill bagasse : 



POUNDS, PER POUND OF BAGASSE 



50 per cent. 75 per cent. 100 per cent, 



excess air. excess air. excess. 



Carbon dioxide . . . . o -94 o -94 o -94 



Water .. . o -81 0-82 0-83 



Nitrogen .... - . 3 '55 4 ^3 4 *7 2 



Oxygen 0-36 0-53 0-71 



At a temperature of o C. and 760 mm. pressure, the volumes of I Ib. 

 carbon dioxide, water vapour, nitrogen, and oxygen, are respectively 8-1, 

 19-8, 12-8, 11-2 cu.ft. At a temperature of 273C.or 523F., which may 

 be taken as representative of that prevailing in flue gases, these volumes 

 are doubled. The volumes of the products of combustion of i Ib. of mill 

 bagasse may then be estimated : 



CUBIC FEET. 



50 per cent. 75 per cent. 100 per cent. 



excess air. excess air. excess air. 



Carbon dioxide ... ..18-2 18-2 18-2 



Water . . . . . . . . 32 ! 32-5 32 .7 



Nitrogen . . . . . . 90 -9 105 -8 121 -o 



Oxygen 8-7 11-9 15-9 



Total . . 149 -9 168-4 187 -8 



These results may be used to compute the required diameter of chimneys 

 or areas of flues. Engineering practice allows a velocity of 20 ft. to 30 ft. 

 per second to the waste gases. It is also customary to take the effective 

 diameter of a chimney as four inches less than the actual diameter. 



Temperature reached in Combustion of Bagasse. One pound of dry 

 bagasse of the typical composition affords on combustion 8,350 B.T.U. 

 with the exact quantity of air for combustion. If the latter is at 32 F., the 

 temperature of combustion T will be found from the following equation : 

 8350 = 0-58 [180 + 970 + 0-48 (T 212)] + T (1-7 X 0-217) + T 

 (0-06 X 0*48) -f- T (4-30 X 0-244), whence T = 4410. 



If the air is at t F. instead of 32 F., the temperature reached will be 

 T + (t- 32). 



In this equation the latent heat of steanl is taken as 970, and the specific 

 heats of steam, nitrogen, and carbon dioxide, as 0-48, 0-24 and 0-22. 



