Scrubbing of Syngas from MSW Pyrolysis-Volatile Re-forming Process with the Co-produced Oil to Remove Tar and Particulates

Synthetic gas from municipal solid waste (MSW) pyrolysis or gasification is usually contaminated with tar, and its economical removal is still pursued. In this research, the volatile compounds from pyrolysis of MSW were re-formed by passing through a hot char bed to be converted into synthetic gas and re-formed pyrolysis oil (RMPO). Then RMPO was used as absorbent to remove the tar and particulates from the synthetic gas, and its performance was compared with that of soybean oil. To prevent the evaporation of light compounds during the absorption process, RMPO left from distillation at 80 and 98 degrees C, respectively, was used as absorbent. The mechanism for tar carrying in the synthetic gas after RMPO absorption was also explored. Research results showed that at 15 degrees C both RMPO and soybean oil had high absorption efficiencies of 97.13% and 98.08% for the tar and 97.36% and 98.58% for particulates, respectively, while at 45 degrees C the removal efficiencies of the two oils for the tar decreased but the removal efficiencies for particulates remained almost the same. In addition, it had been found that the evaporation of compounds with low boiling points from RMPO was the main reason for its low tar absorption efficiency and the lower temperature was recommended. The RMPO left from distillation showed much higher tar removal efficiency; especially after distillation at 98 degrees C, the remaining RMPO behaved the same as soybean oil; and its absorption efficiency for the typical light compounds including benzene, toluene, xylene, styrene, phenol, and indene reached 100%. This research shows that RMPO can be used as an alternative to vegetable oil for cheap tar and particulates removal from synthetic gas.