A novel process design and techno-economic analysis for coal-based polygeneration process of synthetic natural gas, methanol and power

Abstract

With the development of China's economy and industry, demand for natural gas is growing, making coal to synthetic natural gas (CtSNG) a feasible alternative energy supply solution. However, in existing CtSNG projects have been found several issues, e.g., natural gas excess in the non-heating season, low economic performance, low carbon utilization ratio, as well as low energy efficiency. To tackle down the mentioned problems, two novel conceptional schemes are proposed and analyzed in this study in accordance with process modeling and simulation. A coal-based polygeneration process of synthetic natural gas, methanol and power (CtSMP) and a coal-based polygeneration process of synthetic natural gas, methanol and power for adjusted scenario (CtSMPa) are developed for different SNG and methanol outputs to adapt to the change of market demand. In addition, a comprehensive techno-economic analysis is conducted to exhibit the advantages of the proposed polygeneration processes. As compared to CtSNG, CtSMPa and CtSMP achieve an increase of 5.9% and 6.7% in carbon utilization index and in exergy efficiency of 5.5% and 3.9% respectively. Besides, the production costs decrease by 6.6% and 7.6%. Moreover, the internal rate of return increase substantially from 6.82% to 13.32% and 15.52%. In this study, an efficient method is developed to achieve peak shaving of CtSNG process, and guidelines can be supplied to further develop a coal-based polygeneration system with chemicals, energy, power and heat integrated.