CANE SUGAR. 



The heat carried away in the flue gases is then 



Carbon dioxide .. <. .. '939 X '22 (550 84) = 96 B.T.U. 

 Oxygen in excess air . . . . -683 X '22 (550 84) = 71 ,, 



Nitrogen 4*792 X '24 (550 84) =536 



Associated water .. ., ^. .. '45 Xl256 = 565 ,, 

 Combined water \. .. '324x1256= 407 ,, 



Total .. 1675 



The total heat generated by the megass on combustion is, following on 

 a previous paragraph, 8350X'55 = 4582B.T.U. So that in this case the 

 percentage loss in flue gases is 36-6 per cent., leaving 63'4 per cent., or 2905 

 B.T.U. available for making steam. 



As an extreme instance of economical working let the flue gases (due to 

 the use, say, of a fuel economizer) leave at 350 F., and let the excess of air 

 be 50 per cent. Then the heat earned away in flue gases calculated on 

 similar lines as in the case above is 



Carbon dioxide '939 X '22 (350 84) = 55 B.T.U. 



Oxygen in excess air . . . . -341 X '22 (350 84) = 40 ,, 

 Nitrogen .. .... .. 3*694 X '24 (350 84) = 236 ,, 



Associated water -45 X 1160 =522 



Combined water . -324 X 1160= 375 



Total 1228 



In this case, then, the total loss in flue gases is 26*9 per cent, of the heat 

 value of the megass, and 3349 B.T.U. are left available for raising steam. 



In addition, however, there are the losses in unburnt fuel, in hot ashes, 

 and in radiation, the exact magnitude of which it is impossible to estimate. 

 Probably these losses account for 5 per cent, to 10 per cent, of the total value 

 of the megass ; estimating them at the latter figure, in the first instance 

 2440 B.T.U., and in the latter case 2891 B.T.U. will form steam. The 

 evaporation of one Ib. of water from and at 212 F. requires 966 B.T.U., so 

 that referred to this temperature and pressure, 2-55 Ibs. of steam in the one 

 case, and 2 '99 Ibs. in the second would be obtained. 



As compared with coal firing the very great losses due to the associated 

 and combined water met with in the combustion of megass and other low 

 grade fuels should be noticed. 



Consumption of Steam in Proportion to Available 

 Fuel. In " Sugar and the Sugar Cane" the writer was at pains to calculate 

 the heat required to treat the juice obtained from various types of canes, 

 containing different amounts of sugar and fibre, both wet and dry crushed, and 

 also crushed with the addition of maceration water, in order to see how far the 

 megass would serve as fuel. The heat value of the megass was calculated 



414 



