Reducing tar yield in gasification of paper-reject sludge by using a hot-gas cleaning system

A new tar destruction technology has been developed by integrating in-situ catalytic gasification and a hot-gas cleaning system in the catalytic gasification of paper-reject sludge. Experimental results indicated that the tar yield in syngas decreased significantly from 13.64 to 10.76 g/m3, when increasing the zeolite addition during in-situ catalytic gasification. When the syngas passed through the hot-gas cleaning system, the tar concentration measured from downstream was approximately 0.22 g/m3. The hot-gas cleaning system used in this research seems to have played a significant role in reducing tar concentration of the syngas. The major tar speciation identified after hot-gas cleaning system was 1-ring or 2-ring hydrocarbons, which included benzene, toluene, xylene, styrene and naphthalene. In summary, the energy yield efficiency of syngas will be enhanced due to the tar reduction and transformation. The syngas seems to be appropriate to use as a fuel in gas engines for electricity generation.

► An integrated technique for in-situ catalytic gasification and hot-gas cleaning has been well-developed. ► The overall tar concentration decreased significantly from 13.64 to 0.22 g/m3. ► The technique showed a good destruction efficiency of tar with high-ring hydrocarbons. ► The energy yield efficiency can significantly enhance due to tar transformation in gasification.