Coal gasification plant and method for operating the same

Abstract

It is an object to solve a bypass line corrosion problem effectively, enable prompt supply of a fuel gas into a bypass line in the event of an emergency, and provide an inexpensive coal gasification plant. An integrated coal gasification combined cycle power generation plant includes a coal gasification furnace, a dust remover, a gas refiner, a gas turbine and the like, a main system line connecting therebetween, and a bypass line connecting between the outlet side of the coal gasification furnace in the main system line and a flare stack, wherein a dust remover bypass valve which is disposed in an upstream portion of the bypass line and which opens and closes the bypass line, a treatment gas control valve which is disposed in a downstream portion of the bypass line and which controls the flow rate, and a first inert gas input line which is disposed downstream from the dust remover bypass valve and which supplies the inert gas to the bypass line are provided.

1 . A coal gasification plant comprising:
 a coal gasification furnace for gasifying coal to produce a fuel gas;   a dust remover for removing solids in the fuel gas;   a gas refiner for removing sulfides and the like in the fuel gas and supplying the resulting gas serving as a fuel to a gas turbine;   a main system line connecting between the coal gasification furnace, the dust remover, the gas refiner, the gas turbine, and the like; and   a bypass line connecting between the outlet side of the coal gasification furnace in the main system line and a gas treatment unit,   wherein a bypass valve which is disposed in an upstream portion of the bypass line and which opens and closes the bypass line,   a treatment gas control valve which is disposed in a downstream portion of the bypass line and which controls the flow rate, and   a first inert gas input line which is disposed downstream from the bypass valve and which supplies an inert gas to the bypass line are included.   
     
     
         2 . The coal gasification plant according to  claim 1 , comprising:
 a first branch line connecting some midpoint between the dust remover and the gas refiner in the main system line and the bypass line;   a first branch bypass valve disposed in the first branch line; and   a second inert gas input line disposed downstream from the first branch bypass valve.   
     
     
         3 . The coal gasification plant according to  claim 1 , comprising:
 a second branch line connecting between the outlet portion of the gas refiner in the main system line and the bypass line;   a second branch bypass valve disposed in the second branch line; and   a third inert gas input line disposed downstream from the second branch bypass valve.   
     
     
         4 . A method for operating a coal gasification plant in which a fuel gas is produced from coal in a coal gasification furnace, solids are removed from the fuel gas in a dust remover, and desulfurization and the like are performed in a gas refiner so as to supply the fuel gas serving as a fuel to a gas turbine, the method comprising the steps of:
 discharging the fuel gas, which is allowed to flow into a bypass line branched from an outlet portion of the coal gasification furnace and connected to a gas treatment unit, from the bypass line by an inert gas supplied to the side downstream from the bypass valve disposed in the bypass line after the bypass valve is closed, on startup, and maintaining. the pressure in the bypass line nearly at the same level as the pressure of the fuel gas by the inert gas during normal operation.   
     
     
         5 . The method for operating a coal gasification plant according to  claim 4 , the method comprising the steps of:
 discharging the fuel gas, which is allowed to flow into a first branch line branched from an outlet portion of the dust remover and connected to the bypass line, from the first branch line and the bypass line by an inert gas downstream from a first branch valve disposed in the first branch line after the first branch valve is closed, on startup, and maintaining the pressure in the first branch line and the bypass line nearly at the same level as the pressure of the fuel gas by the inert gas during normal operation.   
     
     
         6 . The method for operating a coal gasification plant according to  claim 4 , the method comprising the steps of:
 discharging the fuel gas, which is allowed to flow into a second branch line branched from an outlet portion of the gas refiner and connected to the bypass line, from the second branch line and the bypass line by an inert gas supplied to the side downstream from a second branch valve disposed in the second branch line after the second branch valve is closed, on startup, and maintaining the pressure in the second branch line and the bypass line nearly at the same level as the pressure of the fuel gas by the inert gas during normal operation.