An object of the present invention improves the heat exchange efficiency in the heat exchanger is to effectively gasified gasification feedstock.
Cold-side flow path 36 of the gasification raw material flows, and a gasification raw material to heating, a counter-flow heat exchanger 30 comprising a hot side flow path 37 which treated water in a supercritical state is introduced, counter-flow heat discharging the warm gas raw material in the exchanger 30, by heating and pressing gasified in the supercritical state, and the gasification reactor 50 to discharge the treated water in a supercritical state, from the gasification reactor 50 the has been treated water to a gasification system 100 configured to include a process water passage 55 leading to countercurrent heat exchanger 30, the gas is introduced raw material to the low temperature side flow path 36, it introduced gas raw material was removed from the middle of the low-temperature side flow path 36, to heat the extracted gas raw material, the heated gas raw material, and an external heating means 35 to return to the middle position of the material downstream of the take-out position.