Modelling and assessment of acid gas removal processes in coal-derived SNG production

Solid fuel conversion into Substitute Natural Gas (SNG) enables its use in remote heat and power applications via storage and transportation through the existing natural gas infrastructure. The product gas of an allothermal coal gasification process, requires cleaning and conditioning before the final methanation process. Catalysts' restrictions and grid requirements emerge the need of CO2-and sulfur species removal before the methanator. This paper investigates the different acid gas removal processes through a comparison of their final integration on the coal-to-SNG production chain. Among these technologies, absorption with physical (i.e. Rectisol™, Selexol™) or chemical (K2CO3, MDEA) solvents which have been implemented in various clean syngas production applications are compared for their efficiency and feasibility. The paper presents conceptual designs comparison, mass and energy analyses of the four processes integrated in the coal-to-SNG system, based on AspenPlus™ modelling.