Effect of inherent moisture in collie coal during pyrolysis due to in-situ steam gasification

The influences of inherent moisture in Collie coal during pyrolysis has been studied using a series of Collie coal samples, including the raw coal, dilute acid-washed coal, and demineralized coal samples of both pulverized fuel and millimeter sizes. Coal without drying (moisture content ∼ 20%) and dried coal (moisture < 1%) were pyrolyzed under various conditions in a fixed-bed reactor, a drop-tube/fixed-bed reactor, and a fluidized-bed reactor. Measurement of char reactivity in air was carried out using a thermogravimetric analyzer. The results demonstrated that inherent moisture in Collie coal had a significant influence on the char yield and reactivity, depending on the pyrolysis conditions. Under slow-heating conditions in the fixed-bed reactor, moisture was swept out of the reactor during the long heating process, leading to little influence on char yield and reactivity. However, under fast-heating conditions with continuous coal feeding in the drop-tube/fixed-bed or fluidized-bed reactor, significan...