Computer Simulation of Gas Composition Produced by Underground Coal Gasification

A computer simulation program which calculates chemical equilibrium state of CO, CO2, O2, H2O, H2, CH4 and N2 under arbitral temperature and pressure was made. It shows that CH4 component is large when the temperature is low. On the contrary CO and H2 components are large when the temperature is high. Pressure also gives a certain effect on the gas composition, but it is not so significant compared to the temperature. Then another computer simulation program which calculates the change of the gas components of the flow through the cavity of underground coal gasification (UCG) was made. It shows that the component of the produced gas changes widely according to the thermal condition of UCG cavity. The calculated product gas showed almost same calorific value with the reported calorific value of actual UCG product gas.