Process Synthesis and Optimization of Synthetic Natural Gas (SNG) Plant

Abstract

Synthetic natural gas via coal gasification is an effective alternative for increasing natural gas demands and price. This thesis addresses the conceptual design of synthetic natural gas (SNG) plant to produce the gas with the specification of pipeline natural gas. The first objective of this study is establishing feasible design to satisfy product specification under given design basis. To achieve this purpose, process screening by literature review is carried out and possible four cases are suggested. The results of process simulation by Aspen Plus indicate the Rectisol process and adiabatic methanation reactors in series with recycle are the selected option to satisfy the given condition. From this proposed design, engineering deliverables including process flow diagram, heat and material balance are generated. The results of sensitivity analysis help the optimizing process parameters for a gasifier and methanation reactors.The second objective is the heat recovery by heat pinch analysis. It is shown that steam generation from hot process streams is the effective way to reduce plant operating cost. Aspen Energy analyzer is utilized to organize heat exchanger network.