Effects of Heating Rate and Coal Type on Gas Evolution during Coal Pyrolysis

摘要

In order to get a decisive conclusion on the effect of the heating rate on gas evolution behaviour during coal pyrolysis, the pyrolysis of coal was systematically investigated in thermo-balance using six coals which have different carbon contents ranging from 81 to 88 (wt percent, daf). The heating rate was ranged from 3 deg C/ min to 300 deg C/min. The evolution rates of CH_4, C_2H_4, C_2H_6, H_2, CO and CO_2 were measured. As the heating rate increased, the maximum weight decrease rate and the maximum gas evolution rate were shifted to higher temperatures. The gas and coke yields were decreased and the liquid yield was increased with an increase in the heating rate.Six coals were heated at constant temperatures ranging from 360 deg C to 500 deg C for 180 min. The ultimate volatile matter content at each holding temperature was decided. It was found that the ultimate volatile matter content depended on the coal rank at lower temperatures and a large amount of gas was evolved from low rank coals at a temperature as low as 400 deg C.