Chemical Structure and Properties of Heat Treated Coal in the Early State of Carbonization (VII)

Abstract

Japanese original coals and heat treated coals were employed as samples for high vacuum pyrolysis and following results were obtained.1. The effect of temperature was studied for Yubari coal. The yields of the distillates and gaseous products increased with increasing temperature. The ultimate analysis of distill-ates shows that the carbon content is approximately equal to that of original coal, but the hydrogen content (about 8%) is 2% higher than that of the original coal.2. The effect of coal rank was examined with various kinds of coals, at the fixed heating temperature (500°C). The yields of distillates and gaseous products were found to be proportional to the hydrogen content and oxygen content of original coal, respectively. This suggests that each yield is influenced strongly by hydrogen or oxygen content. And in all kinds of coals, the hydrogen content of distillate is higher than that of original coal. The oxygen content of distillate is almost same with that of the residual coal, but is less than that of original coal.The hydrogen distribution to distillate increases almost linearly with increase in hy-drogen content of original coal, while the hydrogen distribution to residual coal and gaseous products remains constant, irrespective of thehydrogen content of original coal. The oxygen distribution to gaseous products changes under the influence of the oxygen content of original coal, but those to distillate and residual coal remains constent.3. The high vacuum pyrolysis of heat treated caol was performed under the identical condition (500°C) and the effect of heat treatment temperature was investigated. The yields of distillates and gaseous products generally decrease with increasing heat treatment temperature, though there are some exceptions. In heat treated coals, the yield of distillate also decrease curvilinearly with a decrease in hydrogen content of coal samples. However, on the contrary to original coals, the yields of gaseous products decrease rapidly with decreasing oxygen content in heat treated coals. When the atomic composition of distillate is expressed on the H/C-O*/C diagram, O*/C of distillate remains nearly constant apart from heat treatment temperature, and also agrees with O*/C of residual coal.