The Failure Analysis And Safety Assessment Of Cracked Gasifier

Entrained-flow Gasification is widely applied in coal-based gasification due to its high adaptability to coal and grain size, high operating pressure and temperature, high carbon reaction rate and high productivity. Gasifier is the key equipment and its stable and safe operation will directly affect the safety of whole unit. The serious fracture of gasifier of some company took place during service. Therefore, it is significant to find out the damage cause and provide prevention measures.In this paper, the damaged gasifier vessel’s chemical composition, mechanical property, metallographic organization, crack appearance and breaking surface appearance were analyzed firstly. The analysis results show that the material of gasifier cylindrical part is SA516Gr.70, and the main reason of failure is due to lack of water in quench section of gasifier, which led to high cylindrical surface temperature and creep deformation. At last, the bubbled gasifier cylinder broken under the stress of high pressure.After analysis of stress by Ansys software, it was found that the material stress at bubble deformation area is still acceptable, and can meet operation requirement.Safety assessment of bubbled gasifier was conducted. The results show that gasifier is reliable to be in service to the next maintenance period under normal process condition.