Method and system for recovering high-purity co2 from gasification gas

摘要

To provide a method and a system for recovering CO2 from gasification gas, the method and the system being capable of preventing the recovered CO2 from being contaminated with COS, without repeating cooling and heating operations and without increasing the steam consumption, even when the CO2 recovery ratio is changed in recovering CO2 from gasification gas. Gasification gas being produced in a gasifier 10 and containing CO, CO2, COS and H2S is subjected to dust removal in a scrubber 20. Then, a part of the gas is subjected to a CO shift reaction, in which CO is converted into CO2, in a CO shift reactor 30. Another part of the gasification gas is not subjected to the CO shift reaction by means of a bypass 34, and is mixed with the gas after the CO shift reaction. Thereby, the temperature of the mixture gas is set at 180°C to 300°C, and COS in the mixture gas is converted into H2S in a COS converter 40. The H2S is absorbed and removed by a H2S absorption apparatus 50. Then, CO2 is absorbed and removed by a CO2 absorb apparatus.