The area of the heat recovery network has a significant impact on the economic performance of the coal-to-SNG process. This paper proposes a superstructure of the methanation unit, and the number of the methanator, recycle gas extraction position (RGEXP), as well as the operating conditions, are optimized. Simultaneous optimization and heat integration are performed along with the area targeting to weigh against the operating cost and capital cost of the coal-to-SNG process. Area cost is evaluated by assuming vertical heat transfer between cold and hot composite curves. A sequential method is used to provide initial values for the simultaneous model. Results show that Case7 (2) has the best economic performance, which has 7 methanators and recycled gas is extracted from the 2nd methanator. The total annual cost of Case7 (2) can be reduced by 10.36 MM$·a⁻¹, and exergy efficiency can be also improved by 0.77% compared with an industrial plant.

热回收网络的面积对煤制SNG工艺的经济性能有重大影响。本文提出了甲烷化装置的上部结构，并优化了甲烷化器的数量，循环气提取位置（RGEXP）以及操作条件。同时进行优化和热集成以及目标区域，以权衡煤制SNG工艺的运营成本和资本成本。通过假定冷热复合曲线之间的垂直传热来评估面积成本。顺序方法用于为同时模型提供初始值。结果表明，Case7（2）具有最佳的经济性能，它具有7个甲烷化器，并且从第二个甲烷化器中提取了回收气体。Case7（2）的年度总成本可以减少10。^-1，并且与工业设备相比，能效效率也可以提高0.77％。