Method And Apparatus For Implementing Gasification By Combining Circulating Fluidized Bed And Pyrolysis Bed

Abstract

The present disclosure provides a method and an apparatus for implementing gasification by combining a circulating fluidized bed and a pyrolysis bed. The method and the apparatus may be applied to raw coal for generating coal gas with a high raw coal gasification rate while producing no pollutants, such as tar, during gasification. The apparatus includes a circulating fluidized bed gasification furnace and a pyrolysis bed gasification furnace. In the circulating fluidized bed gasification furnace, raw coal is converted to coal gas along with carbon-containing fly ash and semicoke, with the latter two separated from the coal gas using a cyclone separator and a deposition chamber. The semicoke is further processed by the pyrolysis bed gasification furnace to generate more coal gas, whereas the carbon-containing fly ash is sent back to the circulating fluidized bed gasification furnace for further combustion.

1 . A gasification apparatus, comprising:
 a circulating fluidized bed gasification furnace;   a cyclone separator;   a deposition chamber;   a conveyor;   a high-temperature air pipe;   a vapor pipe;   an oxygen pipe;   a fly ash pipe;   a slag pan; and   a gas distribution body,   wherein:
 the circulating fluidized bed gasification furnace is configured to receive raw coal through a coal conveying pipe, 
 an upper portion of the circulating fluidized bed gasification furnace is in communication with an upper portion of the cyclone separator via a first coal gas pipe, 
 a top portion of the cyclone separator is in communication with a top portion of the deposition chamber via a second coal gas pipe, 
 the upper portion of the circulating fluidized bed gasification furnace forms a gasification furnace chamber, 
 a gas distributor is disposed in a middle portion of the circulating fluidized bed gasification furnace, 
 a lower portion of the circulating fluidized bed gasification furnace forms a first mixture gas distribution chamber, 
 the cyclone separator comprises a central cylinder disposed within the upper portion of the cyclone separator, 
 a bottom portion of the cyclone separator is floatingly disposed on the slag pan, 
 a watertight seal is disposed between the slag pan and the bottom portion of the cyclone separator, 
 the gas distribution body is disposed in the bottom portion of the cyclone separator and located on the slag pan, 
 a second mixture gas distribution chamber is formed between the slag pan and a lower portion of the gas distribution body, 
 a lower portion of an inner cavity of the cyclone separator, the gas distribution body, and the second mixture gas distribution chamber located below the gas distribution body collectively form a pyrolysis bed gasification furnace, 
 an oblique guide plate is disposed in an upper portion of the deposition chamber, 
 the conveyor is disposed under a bottom portion of the deposition chamber and is connected to the fly ash pipe, 
 the high-temperature air pipe, the vapor pipe, the oxygen pipe, and the fly ash pipe are in communication with the first mixture gas distribution chamber formed by the lower portion of the circulating fluidized bed gasification furnace, and 
 the high-temperature air pipe, the vapor pipe, and the oxygen pipe are in communication with the second mixture gas distribution chamber located below the lower portion of the gas distribution body. 
   
     
     
         2 . The gasification apparatus of  claim 1 , wherein the oblique guide plate is obliquely disposed in the deposition chamber. 
     
     
         3 . The gasification apparatus of  claim 1 , wherein the gas distribution body is cone-shaped. 
     
     
         4 . The gasification apparatus of  claim 1 , wherein a top portion of the central cylinder of the cyclone separator is in communication with the top portion of the deposition chamber via the second coal gas pipe. 
     
     
         5 . A gasification method, comprising:
 combusting, fluidizing, and gasifying raw coal in an environment having a temperature between 900° C. and 1200° C. in a circulating fluidized bed gasification furnace to generate coal gas, carbon-containing fly ash and semicoke;   feeding the carbon-containing fly ash, the semicoke and the coal gas into an upper portion of a cyclone separator, wherein the semicoke is separated;   introducing the separated semicoke into a pyrolysis bed gasification furnace;   introducing a gasification agent into a bottom portion of the pyrolysis bed gasification furnace;   combusting the separated semicoke in the pyrolysis bed gasification furnace for pyrolysis and gasification;   introducing coal gas generated in the pyrolysis bed gasification furnace, the coal gas generated in the circulating fluidized bed gasification furnace, and the carbon-containing fly ash generated in the circulating fluidized bed gasification furnace into a deposition chamber through a central cylinder of the cyclone separator;   discharging coal slag into a slag pan located at the bottom portion of the pyrolysis bed gasification furnace;   introducing the carbon-containing fly ash deposited in the deposition chamber into a first mixture gas distribution chamber located at a bottom portion of the circulating fluidized bed gasification furnace via a conveyor and a fly ash pipe; and   introducing the carbon-containing fly ash into the circulating fluidized bed gasification furnace to heat along with the gasification agent for circulating gasification and combustion.   
     
     
         6 . The gasification method of claim  45 , wherein the gasification agent introduced into the bottom portion of the pyrolysis bed gasification furnace is a mixed gas of air and water vapor, and wherein the semicoke is combusted and pyrolyzed in the pyrolysis bed gasification furnace. 
     
     
         7 . The gasification method of claim  45 , wherein the gasification agent introduced into the bottom portion of the circulating fluidized bed gasification furnace is a mixed gas of air, water vapor and oxygen, and wherein the raw coal is combusted and pyrolyzed in the circulating fluidized bed gasification furnace. 
     
     
         8 . The gasification method of claim  45 , wherein the gasification agent introduced into the bottom portion of the pyrolysis bed gasification furnace is a mixed gas of air, water vapor and oxygen, and wherein the semicoke is combusted and pyrolyzed in the pyrolysis bed gasification furnace. 
     
     
         9 . A gasification apparatus, comprising:
 a circulating fluidized bed gasification furnace; and   a pyrolysis bed gasification furnace,   wherein:
 the circulating fluidized bed gasification furnace comprises a coal conveying pipe capable of conveying raw coal to the circulating fluidized bed gasification furnace, 
 a first gasification agent is introduced into a bottom portion of the circulating fluidized bed gasification furnace, 
 the raw coal is fluidizedly combusted and pyrolyzed in the circulating fluidized bed gasification furnace to generate coal gas, carbon-containing fly ash, and semicoke, 
 an upper portion of the pyrolysis bed gasification furnace is in communication with an upper portion of the circulating fluidized bed gasification furnace via a coal gas pipe, 
 a coal gas outlet is disposed on the upper portion of the pyrolysis bed gasification furnace, 
 the coal gas, the carbon-containing fly ash, and the semicoke generated in the circulating fluidized bed gasification furnace are configured to enter the pyrolysis bed gasification furnace via the coal gas pipe, 
 the semicoke is configured to drop to a bottom portion of the pyrolysis bed gasification furnace, 
 a second gasification agent is introduced into the bottom portion of the pyrolysis bed gasification furnace, 
 the semicoke is combusted in the pyrolysis bed gasification furnace to be further pyrolyzed and gasified to generate coal gas, and 
 coal slag is discharged to a slag pan located at the bottom portion of the pyrolysis bed gasification furnace. 
   
     
     
         10 . The gasification apparatus of  claim 9 , wherein:
 the upper portion of the circulating fluidized bed gasification furnace forms a gasification furnace chamber,   a gas distributor is disposed in a middle portion of the circulating fluidized bed gasification furnace,   a lower portion of the circulating fluidized bed gasification furnace forms a first mixture gas distribution chamber,   the first gasification agent is introduced into the first mixture gas distribution chamber,   a bottom portion of a furnace body of the pyrolysis bed gasification furnace is floatingly disposed on the slag pan,   a watertight seal is disposed between the slag pan and the bottom portion of the furnace body of the pyrolysis bed gasification furnace,   a gas distribution body is disposed in the bottom portion of the furnace body of the pyrolysis bed gasification furnace and located on the slag pan,   a second mixture gas distribution chamber is formed between the slag pan and a lower portion of the gas distribution body, and   the second gasification agent is introduced into the second mixture gas distribution chamber.   
     
     
         11 . The gasification apparatus of  claim 10 , further comprising:
 a deposition chamber;   a conveyor;   a high-temperature air pipe;   a vapor pipe;   an oxygen pipe; and   a fly ash pipe,   wherein:
 a top portion of the pyrolysis bed gasification furnace is in communication with a top portion of the deposition chamber via a coal gas pipe, 
 an oblique guide plate is disposed in an upper portion of the deposition chamber, 
 the conveyor is disposed below a bottom portion of the deposition chamber and connected to the fly ash pipe, 
 the high-temperature air pipe, the vapor pipe, the oxygen pipe and the fly ash pipe are in communication with the first mixture gas distribution chamber, and 
 the high-temperature air pipe, the vapor pipe and the oxygen pipe are in communication with the second mixture gas distribution chamber.