Simulation of pyrolysis and gasification of sub-bituminous coal using aspen plus

The purpose of this study is to simulate the process of pyrolysis and gasification of subbituminous coal. Simulation of this process was done in order to transform the coal into synthesis gas. This was done by using pyrolysis and gasification process. Gasification is a process where thermochemical reactions takes place. The coal was transformed by partial oxidation into synthetic gases. In the simulation by using Aspen Plus, the main syngas formed is carbon monoxide, hydrogen and carbon dioxide. These gas are used in electricity generation as a fuel to the turbines. In this project, the rigorous model that was used to simulate the pyrolysis and gasification process is R-Yield and R-Gibbs respectively. R-Gibbs model are used to determine the equilibrium composition of the expected products which involves various kinds of chemical reactions. R-Yield model was used to simulate the decomposition yield of the coal based from the ultimate analysis and proximate analysis obtained from references. The R-Yield model was simulated with the help of FORTRAN code which is needed to calculate the amount of yield. A study on the effect of the temperature of the gasifier and the air-fuel ratio on the amount of syngas produced was studied. The temperature was varied from 900⁰C to 2000⁰C and the air ration was varied from 9000kg/hr to 30000kg/hr. A solid-gas separator was used to simulate the separation of the ashes obtained from the pyrolysis process. The main concern of the process is the cleaning of the gas. The results obtained shows that the cyclone which was used for the solid-gas separation was successfully separated with an efficiency as high as 95%.. The efficiency of the cyclone mainly depends on the PSD (particle size distribution) of the coal.