基于Aspen Plus的一步法煤制天然气工艺优化研究

Simulation of coal to gas via a one-step process with Aspen Plus software

选取宁夏梅花井(MH)煤作为研究对象,运用Aspen Plus软件模拟计算了一步法煤制天然气工艺,讨论了气化温度、气化压力、气化剂以及钙基吸收剂对气化产物分布的影响。结果表明,煤水蒸气气化制天然气的适宜条件为:T=600℃,P=5~6MPa,n(H2O)/n(C)=2。n(Ca)/n(C)=0.5时水蒸气的加入量由n(H2O)/n(C)=2降为1.1,1mol C的甲烷产量由0.42mol增加至0.49mol。加入H2且n(H2)/n(H2O)为0.1时,1mol C的甲烷产量增至最大值0.60mol,此时能量转化率为91.2%。以此优化的工况参数进行了固定床煤水蒸气气化实验研究,发现甲烷产率及能量转化率基本与模拟结果一致。所得结果可为煤制天然气的工艺优化提供指导。

The MH coal of Ningxia was selected as the research target. The process simulation software Aspen Plus was used to simulate and calculate the process of producing natural gas from coal via one-step method. The effects of gasification temperature,pressure, gasification agent and calcium-based sorbent on the composition of product gas were studied. The results show that the suitable operation conditions for the production of synthetic natural gas from coal steam gasification are 600℃, 5 MPa and H2O/C molar ratio of 2. At the Ca/C molar ratio of 0.5, when H2O/C molar ratio decreased from 2 to 1.1, the methane output of 1 mol carbon increased from 0.42 to 0.49 mol. When H2 was added and the molar ratio of H2 to H2O was 0.1, the methane output of 1 mol carbon increased to a maximum value of 0.61 mol, and the energy conversion rate reached 91.2%. Experimental study on steam gasification of coal in the fixed bed was carried out under the optimized operation parameters, and it was found that the methane output and energy conversion rate were basically consistent with the simulation results. The results obtained can provide guidance for the process optimization of coal-to-natural gas production.