(745c) Experimental Investigation of Tar Recycling in Biomass Gasification

Tar formation is one of the major problems that hinders the development of biomass gasification process as it lowers the utilization efficiency of the syngas products and has negative effect on downstream process equipment. Extensive efforts have been made on tar control and reduction, while limited investigation have been conducted on tar recycling and reusing in biomass gasification. In this work, biomass and tar mixture at different ratios was fed to gasifiers of varied sizes to understand the impact of tar recycling on gasification. The syngas composition, tar production, ash agglomeration and reactor shut down time were studied. The experiment results show that tar recycling upgrades the syngas because of the decomposition of hydrocarbons, while lowers the syngas quality due to the extra moisture involvement in the gasification process. It is also found syngas compositions depend on the biomass/tar ratios and temperatures. The ash agglomeration problem becomes severe after the feeding of tar and makes it harder to control the reactor.