Research progress and key technology of improving coal tar yield and quality by coal pyrolysis

In order to solve the key technical problems of the low yield of tar and the high heavy components content in tar(boiling points above 360 ℃),which limits the development of coal pyrolysis industry,the major influence factors on the yield and quality of tar are discussed based on the coal pyrolysis mechanism and tar production process.Some constructive methods are proposed in this paper such as change the composition and structure of volatiles by coal pretreatment,devise the new reactor to control the pyrolysis reaction of coal and the secondary reaction of volatiles,adjust synergistically the pyrolysis reaction conditions to increase field and improve the quality of tar.It is expected that the new pyrolysis technology could use the wide particle size-distributed coal and realize the improvement of coal quality through reducing the residence time of volatiles in high temperature zone,restrain the secondary reaction of volatiles,improve light tar content and decrease dust content in tar,build associate controlling methods of pyrolysis reaction conditions and tar component regulation,so as to realize enhancement of the quality of coal pyrolysis.