464 



CHAPTER XXIII 



4, A bagasse of low apparent specific gravity. 



All these causes combined in one cane would be sufficient to account for 

 the actually observed results, although any one might not be of itself of 

 sufficient magnitude to be detected in the routine control ; and, further, the 

 trouble might be accentuated by the objectionable combinations causing 

 an imperfect combustion in the bagasse. 



Furnaces employed in Bagasse Combustion. — The main principle from 

 which the various designs of bagasse furnaces have been developed is the 

 complete combustion of the fuel before the hot gases impinge upon the boiler 

 surface. This end has been obtained by external furnaces, large combustion 

 chambers, arrangements of arches, check walls and baffles designed to cause 

 the gases both to mix and to pass over surfaces of incandescent brickwork, 

 and by the use of waste radiant heat to partially dry the bagasse before 

 combustion begins. These principles seem to have been first clearly enun- 

 ciated by Marie (patent 1017 of [1881), and to have been put into practice 

 by him. In the Figures below are collected a number of typical designs. 



Fig. 277 



Fig. 275 shows a furnace and setting devised by Abel.^^ whose name 

 is usually attached to this design. The bagasse enters at a and falls 

 on to the step grate h. The combustion chamber is formed by the inclined 

 arch k, acting in combination with the check wall e, and beyond this there is 

 formed a supplementary chamber. The storage platform for bagasse is 

 at i i, and this platform enclosed a chamber k whence hot air may pass into 

 the supplementary combustion chamber with the idea of completing any 

 imperfect combustion. Air also enters the furnace through the passage /. 

 The path of the gases is underneath, back through the tubes and out along 

 the side. This type of furnace is largely used in Demerara, where it" was 

 developed. 



Fig. 276 shows a type much simpler than the foregoing, and which 

 is used extensively in the Hawaiian Islands. Here the gases travel under- 

 neath and along the sides and back through the tubes to the main flue. 



The type that has been evolved in Java is shown in Fig. 277. It is 

 noticeable for the steeply inclined grate and for the overhanging arch, a, 

 at the upper portion of the grate and for the baffle, h, running in a reversed 

 direction. In some cases in Java a supplementary furnace is used, with 



