Experimental Study On Mercury Speciation During Coal Pyrolysis And Gasification

Mercury is mainly released to the atmosphere in coal conversion, which cause certainharm for atmosphere environment and human health. Along with the enhancement ofpeople environmental protection consciousness and increasing strict of the environmentalprotection laws，mercury should be strictly controlled. In order to effectively and maturelycontrol mercury, we have to get a fully understanding on mercury release behavior duringcoal conversion.This paper mainly adopt experiment method to analyse mercury behavior in differentpyrolysis and gasification atmosphere.The paper studies mercury behavior in the process of pyrolysis in N₂atmosphere.Study found that temperature is one of the main factors on mercury release. The higher thetemperature is, the higher the release quantity of mercury. Resident time have littleinfluence on release quantity and formation distribution of mercury.The paper studies mercury behavior in the process of pyrolysis in H₂O/N₂atmosphere.Study found that when coal pyrolysis and gasification temperature is low, the increase ofthe content of water vapor have little influence on mercury behavior.But at hightemperature, such as800℃and1000℃, with the increase of the content of water vapor,mercury’s release quantity will increase. water vapor promote the mercury conversion fromelemental mercury to divalent mercury.The paper studies mercury behavior in the process of pyrolysis in H₂O/CO₂atmosphere. Study found that when coal pyrolysis and gasification temperature is low, theincrease of the content of water vapor （the reduce of the content of CO₂） have littleinfluence on mercury behavior. But at high temperature, such as800℃and1000℃, withthe increase of the content of water vapor（the reduce of the content of CO₂）, mercury’srelease quantity will decrease. When the gasification temperature is high, compared withwater vapor, carbon dioxide is more useful to promote the release of mercury.