Gasification system

Abstract

A gasification system includes a countercurrent type heat exchanger that includes a low-temperature side flow channel through which a gasification feedstock flows, and a high-temperature side flow channel to which treated water in a supercritical state is introduced. The treated water raises a temperature of the gasification feedstock by exchanging heat with the gasification feedstock. The system further includes a reactor that gasifies the gasification feedstock, whose temperature has been raised by the countercurrent type heat exchanger, by heating and pressurizing the gasification feedstock to be in a supercritical state. The reactor discharges the gasification feedstock as treated water in the supercritical state. The system further includes a treated water flow channel that introduces, to the countercurrent type heat exchanger, the treated water that has been discharged from the reactor, and a feedstock introduction port that introduces the feedstock to the low-temperature side flow channel.

1 . A gasification system comprising:
 a countercurrent type heat exchanger that includes a low-temperature side flow channel through which a gasification feedstock flows, and a high-temperature side flow channel to which treated water in a supercritical state is introduced, wherein the treated water raises a temperature of the gasification feedstock by exchanging heat with the gasification feedstock;   a gasification reactor that gasifies the gasification feedstock, whose temperature has been raised by the countercurrent type heat exchanger, by heating and pressurizing the gasification feedstock to be in a supercritical state, wherein the gasification reactor discharges the gasification feedstock as treated water in the supercritical state;   a treated water flow channel that introduces, to the countercurrent type heat exchanger, the treated water that has been discharged from the gasification reactor;   a feedstock introduction port that introduces the gasification feedstock to the low-temperature side flow channel; and   an external heater that extracts, from the middle of the low-temperature side flow channel, the gasification feedstock that has been introduced by the feedstock introduction port, heats an extracted gasification feedstock, and returns a heated gasification feedstock to a middle position on a feedstock downstream side of a position in which the gasification feedstock has been extracted.   
     
     
         2 . The gasification system according to  claim 1 , wherein
 a position in which the extraction is performed is determined based on a value of specific heat at constant pressure of the gasification feedstock, and the gasification feedstock is extracted from the position that has been determined.   
     
     
         3 . The gasification system according to  claim 1 , wherein
 specific heat at constant pressure of the water at the position in which the extraction is performed is 10 kJ/kg·K or greater.   
     
     
         4 . The gasification system according to  claim 1 , wherein
 the low-temperature side flow channel includes a low-temperature zone in which a temperature of the gasification feedstock introduced by the feedstock introduction port is raised, and a high-temperature zone in which a temperature of the gasification feedstock that has passed through the low-temperature zone is raised again, and   the external heater extracts the gasification feedstock from a high temperature end of the low-temperature zone and returns the gasification feedstock to a low temperature end of the high-temperature zone.   
     
     
         5 . The gasification system according to  claim 1 , wherein
 heating by the external heater is performed in a preheater that preheats the gasification feedstock whose temperature has been raised by the countercurrent type heat exchanger.