Abstract
Sewage sludge is a stable biomass resource, but its energy utilization rate is low. Among the technologies for converting sewage sludge to energy, thermal pyrolysis and gasification is a promising pathway to generate electricity from the fuel gas produced or to convert it into hydrogen and chemical feedstocks, however, presence of small amounts of tar in the fuel gas has hindered its widespread application.
Here, the authors proposed a three-reactors circulating fluidized bed pyrolysis-gasification system with olivine, which shows catalytic activity for tar reforming, as a fluidizing medium for producing fuel gas from sewage sludge. In this paper, we report the results of gasification tests of dried sludge using a two-stage bubbling fluidized bed experimental setup developed to investigate and evaluate the effect of the type of fluidizing medium on the gasification behavior of sewage sludge.
Experimental results confirmed that the use of olivine as a fluidizing medium reduced the tar concentration by 94% and increased fuel gas recovery by approximately 1.8 times compared to silica sand, suggesting olivine as an effective fluidizing medium for a fluidized bed gasification system for energy recovery from sewage sludge.
