EFFECTS OF TEMPERATURE, PRESSURE, AND CARRIER GAS ON THE CRACKING OF COAL-TAR OVER A CHAR-DOLOMITE MIXTURE AND CALCINED DOLOMITE IN A FIXED-BED REACTOR

A distillation fraction of a coal-derived liquid (tar) was cracked ove r a char-dolomite mixture, calcined dolomite, and silicon carbide in a fixed-bed reactor. The char-dolomite mixture (FWC) was produced from Pittsburgh No. 8 coal and dolomite in a Foster Wheeler carbonizer. The experiments were conducted under nitrogen and simulated coal gas (SCG ), which was a mixture of CO, CO2, H2S, CH4, N-2, and steam, at 1 and 17 atm. The conversion over these materials under nitrogen was much hi gher at 17 atm than at 1 atm. At higher pressures, tar molecules were trapped in the pores of the bed material and underwent secondary react ions, resulting in the formation of excess char. However, when nitroge n was replaced by SCG, the reactions that induce char formation were s uppressed, thus increasing the yield of gaseous products. The analysis of the gaseous products and the spent bed materials for organic and i norganic carbons suggested that the product distribution can be altere d by changing the carrier gas, temperature, and pressure.