Powder fuel combustion apparatus and combustion method

Abstract

The invention provides a combustion apparatus and a combustion method capable of ashing matter to be combusted inside a combustion chamber efficiently without providing a device such as an unburned combustibles measurement device and without varying the direction of injection of air into the combustion chamber. The powder fuel combustion apparatus 1 includes a fuel supply device 10, a primary combustion chamber 20, a secondary combustion chamber 50, an air supply/ash discharge device 32, and a cyclone dust collector 60. An inclined portion 23a is formed at a bottom portion 23 of the primary combustion chamber 20, and the inclined portion 23a includes bottom portion air supply ports 31 and an air supply/ash discharge device 32. The air supply/ash discharge device 32 includes a bottom portion air injection nozzle 34 and an ash delivery device 35. The bottom portion air injection nozzle 34 has upper and lower ends opened, and a plurality of injection ports 34a through which air is injected are formed on a side surface. During combustion of the powder fuel F, air having a strong wind pressure is injected through the bottom portion air injection nozzle 34 either regularly or irregularly to agitate the powder fuel F and achieve a good combustion state.

1 . A combustion apparatus for combusting a powder fuel, comprising:
 a primary combustion chamber configured to combust the powder fuel in an interior thereof, and a secondary combustion chamber configured to combust a combustion gas discharged from the primary combustion chamber,   wherein the primary combustion chamber comprises a fuel supply device configured to supply the powder fuel to an interior thereof, a primary air supply port configured to supply air to an interior thereof, and an ignition burner configured to ignite the powder fuel in an interior thereof,   wherein a bottom portion of the primary combustion chamber comprises an inclined portion inclined to narrow toward a lower direction, a bottom portion air supply port configured to supply air to an interior thereof, an ash outlet provided at a lower position of the inclined portion, and a bottom portion air injection nozzle having a tubular shape and arranged in a vertical direction, the bottom portion air injection nozzle comprising openings formed on an upper end and a lower end thereof, the lower end positioned toward the ash outlet, and having air supplied to an interior thereof,   wherein the secondary combustion chamber comprises a secondary burner configured to heat an interior thereof and ignite a combustion gas discharged from the primary combustion chamber, and a secondary air supply port configured to supply combustion air to an interior thereof,   a primary air supply device configured to supply air to the primary air supply port and the bottom portion air supply port, an injection air supply device configured to supply air to the bottom portion air injection nozzle, and a secondary air supply device configured to supply air to the secondary air supply port, and   a controller configured to control operation of the fuel supply device, the ignition burner, the secondary burner, the primary air supply device, the injection air supply device, and the secondary air supply device,   wherein the controller is configured to   accumulate a predetermined amount of the powder fuel in the primary combustion chamber by the fuel supply device,   ignite the powder fuel being accumulated using the ignition burner and activate the secondary burner to heat the interior of the secondary combustion chamber,   upon performing gasification combustion of the powder fuel being accumulated, activate the primary air supply device and the injection air supply device to supply an amount of air that is smaller than an amount of air necessary for complete combustion of the powder fuel being accumulated through the primary air supply port, the bottom portion air supply port, and the bottom portion air injection nozzle to generate flammable gas inside the primary combustion chamber,   upon performing direct combustion of the powder fuel being accumulated, activate the primary air supply device and the injection air supply device to supply an amount of air necessary for direct combustion of the powder fuel into the primary combustion chamber through the primary air supply port, the bottom portion air supply port, and the bottom portion air injection nozzle, and activate the fuel supply device to supply the powder fuel into the primary combustion chamber to combust the powder fuel and activate the fuel supply device as a burner, and   upon performing gasification combustion of the powder fuel being accumulated and performing direct combustion of the powder fuel being accumulated, activate the secondary air supply device to supply an amount of secondary combustion air necessary for complete combustion of the flammable gas through the secondary air supply port to combust the flammable gas.   
     
     
         2 . The powder fuel combustion apparatus according to  claim 1 ,
 wherein, upon performing ember combustion and ashing of the powder fuel in the primary combustion chamber, supply of fuel by the fuel supply device is stopped, and supply of air from the bottom portion air injection nozzle is also stopped.   
     
     
         3 . The powder fuel combustion apparatus according to  claim 1  or  2 ,
 wherein, upon performing gasification combustion of the powder fuel being accumulated and upon performing direct combustion of the powder fuel being accumulated, the controller is configured to control the injection air supply device so as to inject air by an amount of injection capable of agitating the powder fuel either regularly or irregularly through the bottom portion air injection nozzle. 
 
     
     
         4 . The powder fuel combustion apparatus according to any one of  claims 1  through  3 ,
 wherein the fuel supply device comprises a fuel hopper through which the powder fuel is loaded, a hopper injection nozzle arranged in a vertical direction in the fuel hopper to inject air at least to a lower direction thereof, a hopper air supply device configured to supply air to the hopper injection nozzle, a fuel delivery device arranged at a lower direction of the hopper injection nozzle and delivering the powder fuel to the lower direction, a mixing pipe in which the powder fuel and air are mixed, and a fuel blower configured to supply air to the mixing pipe, and 
 upon supplying the powder fuel to the primary combustion chamber, the controller is configured to activate the fuel blower and also activate the fuel delivery device, mix the powder fuel and air supplied from the fuel blower in an interior of the mixing pipe and supply the powder fuel from the mixing pipe to the primary combustion chamber, and activate the hopper air supply device at a predetermined timing to inject air through the hopper injection nozzle. 
 
     
     
         5 . A combustion method of combusting a powder fuel by a powder fuel combustion apparatus, comprising:
 a fuel charging step, an igniting step, a gasification combustion step, a direct combustion step, and an ember-ashing step,   wherein the powder fuel combustion apparatus comprises   a primary combustion chamber configured to combust the powder fuel in an interior thereof, and a secondary combustion chamber configured to combust a gas discharged from the primary combustion chamber,   wherein the primary combustion chamber comprises a fuel supply device configured to supply the powder fuel to an interior thereof, a primary air supply port configured to supply air to an interior thereof, and an ignition burner configured to ignite the powder fuel in an interior thereof,   wherein a bottom portion of the primary combustion chamber comprises an inclined portion inclined to narrow toward a lower direction, a bottom portion air supply port configured to supply air to an interior thereof, an ash outlet provided to a lower position of the inclined portion, and a bottom portion air injection nozzle having a tubular shape and arranged in a vertical direction, the bottom portion air injection nozzle comprising openings formed on an upper end and a lower end thereof, the lower end positioned toward the ash outlet, and having air supplied to an interior thereof,   wherein the secondary combustion chamber comprises a secondary burner configured to heat an interior thereof, and a secondary air supply port configured to supply combustion air to an interior thereof,   a primary air supply device configured to supply air to the primary air supply port and the bottom portion air supply port, an injection air supply device configured to supply air to the bottom portion air injection nozzle, and a secondary air supply device configured to supply air to the secondary air supply port, and   a controller configured to control operation of the fuel supply device, the ignition burner, the secondary burner, the primary air supply device, the injection air supply device, and the secondary air supply device,   wherein the controller is configured to   accumulate a predetermined amount of the powder fuel to the primary combustion chamber by the fuel supply device in the fuel charging step,   heat the interior of the secondary combustion chamber by the secondary burner, and after the interior of the secondary combustion chamber has reached a predetermined temperature, ignite the powder fuel being accumulated using the ignition burner in the igniting step,   supply an amount of air that is smaller than an amount of air necessary for complete combustion of the powder fuel being accumulated through the primary air supply port, the bottom portion air supply port, and the bottom portion air injection nozzle to generate flammable gas in the primary combustion chamber, introduce the flammable gas to the secondary combustion chamber, and perform complete combustion of the flammable gas by supplying air for secondary combustion through the secondary air supply port in the gasification combustion step,   activate the primary air supply device and the injection air supply device to supply an amount of air necessary for direct combustion of the powder fuel into the primary combustion chamber through the primary air supply port, the bottom portion air supply port, and the bottom portion air injection nozzle, activate the fuel supply device to supply the powder fuel into the primary combustion chamber and perform combustion of the powder fuel to activate the fuel supply device as a burner, introduce combustion gas discharged from the primary combustion chamber to the secondary combustion chamber, and perform complete combustion of the combustion gas by supplying air for secondary combustion through the secondary air supply port in the direct combustion step, and   stop supply of fuel by the fuel supply device and perform ember combustion and ashing of the powder fuel remaining in the primary combustion chamber in the ember-ashing step.   
     
     
         6 . The powder fuel combustion method according to  claim 5 ,
 wherein, in the ember-ashing step, supply of air from the bottom portion air injection nozzle is stopped.   
     
     
         7 . The powder fuel combustion method according to  5  or  6 ,
 wherein, in the gasification combustion step and the direct combustion step, the controller is configured to control the injection air supply device so that air is injected by an amount of injection capable of agitating the powder fuel to the bottom portion air injection nozzle either regularly or irregularly. 
 
     
     
         8 . The powder fuel combustion method according to any one of  claims 5  to  7 ,
 wherein the fuel supply device comprises a fuel hopper through which the powder fuel is loaded, a hopper injection nozzle arranged in a vertical direction in the fuel hopper to inject air at least to a lower direction thereof, a hopper air supply device configured to supply air to the hopper injection nozzle, a fuel delivery device arranged at a lower direction of the hopper injection nozzle and delivering the powder fuel to the lower direction, a mixing pipe in which the powder fuel and air are mixed, and a fuel blower configured to supply air to the mixing pipe, and 
 in the fuel charging step and the direct combustion step, the controller is configured to activate the fuel blower and also activate the fuel delivery device, mix the powder fuel and air supplied from the fuel blower in an interior of the mixing pipe and supply the powder fuel from the mixing pipe to the primary combustion chamber, and activate the hopper air supply device at a predetermined timing to inject air through the hopper injection nozzle.