ENERGY AND EXERGY ANALYSIS OF GASIFIER-BASED COAL-TO-FUEL SYSTEMS

Interests in coal-to-liquid (CTL) and other fuels have grown greatly in the last Couple of years with steadily increasing oil prices. National energy security concerns related to liquid transportation fuels also have revived interests in alternative liquid fuel Sources. Coal-to-fuel technologies feature high efficiency energy conversion and environmental advantages. While a number of factors are driving coal-to-fuel projects forward, there are several barriers to wide commercialization, such as financial, construction, operation, and technical risks. The purpose of this study is to investigate the performance features of CTL and other coal-to-fuel systems based on different gasification technologies. The target products are Fischer-Tropsch (F-T) crude and synthesis natural gas (SNG). Two types of entrained-flow gasifier based coal-to-fuel systems are simulated and their performance features are discussed. One is single-stage water quench (WQ) cooling entrained-flow gasifier, and another is two-stage syngas cooling (SC) entrained-flow gasifier. The conservation of energy (first law of thermodynamics) and the quality of energy (second law of thermodynamics) for the systems are both investigated. The results of exergy analysis provide insights about the potential targets for technology improvement. The features of different gasifier-based coal-to-fuel systems are discussed. The results provide information about the research and development priorities in future.