Process and apparatus for continuous dry removal of bottom ash

Abstract

Provided is a process to continuously dry remove ash from the bottom of steam boilers by discharging the ash on a high temperature resistant conveyer which is enclosed in a tight sealed envelope. Also is provided an apparatus for accomplishing this which has a steel conveyer belt constructed to withstand high temperatures and enclosed in a sealed steel box connected to the bottom of the boiler so that the conveyer continuously receives and discharges ash from the boiler.

I claim: 
     
       1. A system for continuously removing bottom ash from a .[.fire bed.]. .Iadd.fired boiler.Iaddend., said system comprising a .[.first and.]. flexible conveyor belt made of high temperature resistant material trained over a drive drum with a friction fit therebetween, a plurality of overlapping load bearing plates loosely joined to said conveyor belt for bearing the weight of a load deposited on said belt, whereby temperature caused expansion and contraction of said conveyor belt is absorbed by said plates sliding relative to each other in said overlap area, and a tightly sealed envelope means surrounding said conveyor belt in order to retain heat of said .[.fire bed.]. .Iadd.fired boiler .Iaddend.while enabling said ash to be conveyed out of a .[.furnace in which said fire bed is located.]. .Iadd.combustion chamber of said fired boiler.Iaddend.. 
     
     
       2. The system of claim 1 wherein said conveyor belt is a woven wire belt. .[.3. The system of claim 2 and means down stream of said conveyor for cyclically discharging ash from said conveyor belt while precluding an 
     
     
        escape of a significant amount of heat from said envelope means..]. 4. The system of claim .[.3 and means wherein said downstream means returns.]. .Iadd.2 including valve means, located in said envelope means, for returning .Iaddend.air to said .[.fire bed.]. .Iadd.fired boiler.Iaddend., the returned air passing over said conveyor belt in order to recapture heat from said hot ash, said heat being returned to said .[.fire bed.]. .Iadd.fired boiler .Iaddend.when said returning air reaches said .[.furnace in which said fire bed is located.]. .Iadd.combustion chamber.Iaddend.. .[.5. The system of claim 1 and means at fire bed for 
     
     
        continuously depositing hot ash on said conveyor belt..]. 6. The system of claim 1 wherein said overlapping plates form a trough .[.under said flexible.]. .Iadd.over a load bearing run of said conveyor .Iaddend.belt. 
     
     
         . The system of claim 1 wherein said conveyor belt is a woven wire belt and said loosely joined plates are connected to said woven wire belt by bolts or rivets which are free to slide and move within the weave of said 
     
     
        woven wire. 8. The system of claim 7 wherein said woven wire belt includes a plurality of cross pieces slipped into the weave of said woven wire, 
     
     
        said bolts or rivets being joined to said crosspieces. 9. The system of claim 1 .[.and a second.]. .Iadd.including a .Iaddend.guide drum, said conveyor belt being trained over said .[.second.]. guide drum, and means for adjusting .[.the.]. .Iadd.a .Iaddend.position of said .[.second.]. 
     
     
        guide drum to tension said conveyor belt. 10. The system of claim 1 .[.and.]. .Iadd.including .Iaddend.a plurality of rollers for supporting said conveyor belt and said plates, said rollers .Iadd.having ends .Iaddend.extending outwardly from said conveyor belt to an area which is much cooler than said ash, and bearing means for supporting the ends of 
     
     
        said rollers. .Iadd.11.  The system of claim 1, wherein the conveyor belt receives the ash discharged from the boiler in a first direction; and wherein the system further comprises   a cyclically activated valve, located in the envelope means downstream from an area where the ash is received onto the conveyor belt, for controlling entrance of cool air and for delivering the cool air controlled by the valve in a second direction countercurrent with respect to the first direction of ash discharge so that heat yielded to the air by the ash and by combustion of unburnt matter on the conveyor belt is returned into the boiler so as to increase its efficiency. .Iaddend.