H PI 



MEGASS AS FUEL. 



the carrier <? which conveys it to the furnaces. The carriers are formed entirely 

 of metal and are driven at a speed of from six to eight feet per minute, the 

 megass remaining in the secherie from 15 to 20 minutes ; the flue gases enter 

 at d and leave through the smoke stacks at/; at g are shown doors for cleaning 

 up the megass which falls to the ground, and at e a door gives access to the 

 interior in case of accidents. Three engines are required, one to drive the fan, 

 one to drive the carriers in the secherie, and one for the cross-carrier from the 

 secherie to the furnaces. On an average as many as 15 to 20 labourers are 

 required, chiefly for the purpose of sweeping up and carrying to the furnaces 

 the megass which falls down. The megass in the secherie is liable to ignite, 

 and will invariably do so if the temperature of the waste gases exceeds 550F. 

 There is a very considerable and undeterminable mechanical loss due to the 

 finer light and dry particles of megass being carried away ; and finally the 

 megass in the furnaces is so fine that it falls through the furnace bars, and is 

 liable to be swept through the flues unburnt. 



Another design to 

 the same end is shown 

 in the Huillard 7 Drier in 

 Fig. 225 (PLATE XX.), 

 The economy of these 

 devices can be shown 

 by the following cal- 

 culations. 



In Mauritius the 

 writer found that megass 

 entering a secherie with 

 50 per cent, of moisture 

 would leave containing 

 only 35 per cent. ; this 

 amount of water corresponds very closely with the evaporation of half the 

 original moisture. In a calculation of heat lost in flue gases in a previous 

 paragraph 565 B.T.U. per Ib. of megass were found to be carried away in the 

 associated water ; a saving of half of this would be 282 B.T.U., reducing the 

 heat carried away in flue gases to 1393 B.T.U., and expressed as a percentage 

 on the total heat of megass the loss in flue gases will now be 30 A per cent, 

 as compared with 36-6 per cent, as previously calculated. 



Value of Megass as compared with other Fuels. The 



relative value of megass, wood and coal is often required, as fuel statistics are 

 generally based on the coal value of the fuel burnt. There is no constant fuel 

 value for either megass or coal, and any factor adopted depends on the local 

 conditions ; coal, depending on its quality and the skill used in firing, may 

 give from 7 to 12 Ibs. of steam per Ib. consumed. On an average from 4 to 5 



Q 



Q 



Q 



FIG. 224. 



419 



