466 



CHAPTER XXIII 



The grates themselves are either flat bar, step grate, or flat grates. 

 The first-mentioned type has almost disappeared. Sections of forms of 

 step grates are shown in Fig. 282. The type on the extreme right comes 

 from Java, and eliminates one d fficulty of the step grate, namely a tendency 

 for the bagasse to feed forward unevenly. 



I 



I 



^mmm^ 



V////y///////////////A^^\^\\\<s^>///////////y 



Fig. 280 



Besides the grate proper, an ntegral portion of the furnace is the ash grate 

 ind cated in the above sketches at the lower portion of the inclined portion. 

 Frequently a large air space is left between these two elements both for the 

 admission of air and for the removal of clinker. In other designs the ash 

 grate is made so as to allow of pivoting to aid in clinker removal. 



The flat grate shown in Fig. 280 is intended to be used with forced draught, 

 and may, of course, be applied to any other type of furnace and boiler. 



Fig. 281 



A point wherein considerable difference in practice exists is the ratio 

 of openings between fire bars to total area of grate. Generally the area is 

 approximately evenly divided between bar and opening, but examples may 

 be found with either twice as great as the other. 



All schemes now used in the stoking or firing of bagasse ma}'^ be referred 

 back to Fryer and Alliott's patent (284 of 1883), other essential principles of 



