Experimental study of Zn-Sn based liquid metal carbon gasification

Liquid metal gasification is a clean energy technology to convert solid carbon material into gaseous fuels. Be- cause of its capability to convert various types of fuels,the air separation sub-system is no longer required. Liquid met- al gasification is a promising technology to fulfill the demand of distributed gaseous fuel supplement. During its opera- tion,liquid metal in the gasifier is oxidized to metal oxide,and then carbon material (e. g. coal,coke,biomass,munici- pal waste etc. ) is fed to the gasifier to reduce the metal oxide and produce CO rich gas. In order to increase the CO content in product gas,the oxide of active metal such as zinc oxide ( ZnO) is introduced into gasifier to promote CO production rate. The temperature programmed experiments in the present study have shown that the oxygen transfer from zinc oxide to carbon is rate determining step in the whole gasification process. Therefore,alkaline metal carbonate is introduced into the system to accelerate the oxygen ion transfer inside bed material. The alkaline metal carbonate melts at a given temperature,and builds oxygen ion transport pathways between zinc oxide and carbon. In the present study,sodium carbonate ( Na2 CO3 ) and potassium carbonate ( K2 CO3 ) were tested and Na2 CO3 ,as one process a higher oxygen ion conductivity achieved a higher gasification performance than Na2 CO3 did. A mixture made of Na2 CO3 and K2 CO3 ,which possess a melting point of nearly 720 ℃ ,was also tested in the present study,and by melt- ing and building oxygen transport pathways in bed material,carbon gasification reaction was triggered at a lower temperature.