Experimental study on the two-stage purification of retorting gas in the process of pulverized coal pyrolysis

To solve the problem of separating coal dust from retorting gas in the process of pulverized coal pyrolysis,a two-stage dust removal apparatus consisting of cyclone separator and fixed granular bed filter was designed. Using the apparatus,a research on the dust removal performance of cyclone separator and fixed granular bed filter was carried out,and the effects of different factors like filter media,temperature and gas components on the dust removal perform-ance were investigated. The results indicates that the cyclone separator can remove the dust whose size is larger than 28 μm,and the granular bed filter can further remove the dust whose size is smaller than 28 μm,together contributing to an overall dust removal efficiency of 99. 89% . Meanwhile,semi-coke shows a better filtration performance than silica sand as the filter material of granular bed filter. In addition,the increase in temperature reduces the filtration efficien-cies of the cyclone separator and the granular bed filter,in particular,the granular bed filter. However,when the retor-ting gas contains tar gas,part of the tar oil will condense inside the granular bed filter,which promotes the filtration ef-ficiency of the granular bed filter to a certain extent and improves the tar quality.