STEAM BOILERS 149 



desired pressure and to burn the fuel with economy. Different 

 fuels require different handling and hence only general rules 

 can be given; much will depend on the skill and judgment of 

 the attendant, who must himself discover in each case by 

 actual trial the best method to pursue. The fires must be 

 cleaned at intervals; the time and method of cleaning depend 

 on conditions such as the nature of the fuel, the rapidity with 

 which it is being consumed, the style of grate in use, and the 

 construction of the furnace. Here much is left to the choice 

 and judgment of the attendant, who should readily discover 

 what is best to be done in any particular case. 



Cleaning of Fires. There are two methods employed in 

 cleaning the fires: first, that of cleaning the front half and then 

 the rear half; second, that of cleaning one side of the fire and 

 then the other side. In the first method, previous to cleaning, 

 green fuel is thrown on and allowed to burn partly until it 

 glows over the entire surface. The new and glowing fuel is 

 then pushed to the back of the furnace with a hoe, leaving 

 nothing on the front half of the grate but the ashes and clinkers, 

 which are then pulled out, leaving the front end of the grate 

 entirely bare. The new fire which had been pushed back is 

 now drawn forwards and spread over the bare half of the grate. 

 The ashes and clinkers that are on the rear half of the grate 

 are then pulled over the top of the front half of the fire 

 and out through the furnace door; this leaves the rear half 

 of the grate bare, which must be covered by pushing back 

 some of the new front fire. The clean fire having been 

 spread evenly, some new fuel must be spread over the entire 

 surface. 



The second method referred to is substantially the same in 

 principle as that just described, with the difference that the 

 fire is pushed to one side instead of to one end of the furnace, 

 as in the first method described. The condition of the fires 

 themselves and the nature of the service of the plant will 

 determine just how often and at what time the cleaning of 

 fires should take place. In general, the fires in stationary 

 boilers require cleaning at intervals of from 8 to 12 hr. Fires 

 require cleaning more often when fqrced draft is used than when 

 working with natural draft. 



