Influence law study of temperature on low rank coal pyrolysis products distribution and quality with inner-rotatory moving bed reactor

The yield and characteristic of pyrolysis products of low rank coal are closely related to the reactor type and process conditions such as pyrolsis temperature,and further also influence development and extension of downstream processing chain,which attracts more attention during the R&D of new pyrolysis technology.In order to obtain the optimal pyrolysis process conditions to meet the requirements of subsequent large-scale utilization of pyrolysis products，a continuous experimental equipment of an inner-rotatory moving bed reactor with processing capacity of 1 kg/h,was used to research the influence of temperature on the pyrolysis products yield and quality of Shenmu coal，and the characterization of products,including the combustibility,grindability and stability of semicokes,yield and components distribution of coal tar and so on.The results showed that the yields of semicoke were from 68.53% to 78.62% under conditions of pyrolysis temperature at 500～800 ℃ and pyrolysis time 150 min,coal tar yield reached the max value 7.52% at 650 ℃ with increasing pyrolysis temperature.The volatile component of semicokes fluctuated less than 1 percentage point during continuous tests,meanwhile,ignition performance were at the levels of high or medium combustible with the ignition temperature of 562.1～730.5 ℃.Hardgrove grindability index of semicokes increased at first and then decreased with increasing pyrolysis temperature.The pyrolysis temperature of 600～700 ℃ was suitable condition for the new technology to produce semicokes that satisfied the quality requirements of large-scale power plant boiler and blast furnace injection,and obtained a higher tar yield at the same time.Quality of coal tar could be controlled by reducing the temperature rise using the method of stratified temperature distribution.When the bottom temperature of the reactor was 650 ℃ and the temperature of the middle and upper parts is 450～550 ℃, the lowest content of heavy components (>360 ℃ fraction) in tar was 25.68%, which is conducive to further distillation and hydrogenation. When the temperature of middle and upper part was higher than 550 ℃, the secondary reaction of volatiles would be intensified, which led to the decrease of light components.