Exergetic analysis of coal gasification processes

In this study, the efficiency and economics of the Synthane Gasification process are evaluated and discussed. The efficiency of the Synthane process was determined using the exergy analysis (availability) approach to process evaluation. The exergy analysis utilizes both the first and second laws of thermodynamics to determine the efficiency of a process, and is very useful in determining the causes of inefficiency. In order to accurately apply the exergy analysis, it is essential that the absolute enthalpy and entropy values of each stream be determined. In this study, methods for predicting the enthalpy and entropy of coal, char, tar, and ash, as a function of temperature and material composition previously developed were used. A computer simulation of the Synthane process was developed which allowed for the effect of changes in plant operating parameters on both the efficiency and economics. The simulation included a three-section model of the Synthane fluidized bed gasifier.