Abstract: By comparing the corrosion of operating crude gas preheaters of the shift units matching different coal gasification processes, this paper analyzes the process conditions and material selection of various crude gas preheaters based on such factors as the medium characteristics and material selection requirements of different crude gas preheaters. It is finally concluded that the direct corrosion cause of the crude gas preheaters of the shift units matching different coal gasification processes is that the operating temperature of the crude gas is lower than the dew point temperature of the superheated high-temperature transform gas with which it is exchanged. As a result, the high-temperature transform gas is instantly chilled below the dew point temperature at the wall of the heat exchange tube, and thus dew point corrosion occurs.

Key words: waste boiler gasification of pulve-rized coal, change, untreated gases preheater, corrosion