Energy and Exergy Analysis of Gasifier-Based Coal-to-Fuel Systems

Abstract

National energy security concerns related to liquid transportation fuels 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 of these technologies such as financial, construction, operation, and technical risks. The purpose of this study is to investigate the performance features of coal-to-fuel systems based on different gasification technologies. The target products are the Fischer–Tropsch synthetic crude and synthetic natural gas. Two types of entrained-flow gasifier-based coal-to-fuel systems are simulated and their performance features are discussed. One is a single-stage water quench cooling entrained-flow gasifier, and another one is a two-stage syngas cooling 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.