煤炭地下气化采出气的脱碳工艺优化及能效分析

煤炭地下气化（underground coal gasification，UCG）产生的混合气由地下输送至地面进行集输和处理，为了以较低能 耗脱除混合气中的CO2，使净化气中CO2的摩尔分数低于3%，本文采用Aspen HYSYS软件对半贫液脱碳流程进行了敏感性分析、参数优化和流程优化，提出了一种节能降耗脱碳新工艺，并对新工艺进行了能效分析。流程模拟选用哌嗪活化的甲基二乙醇胺（PZ+MDEA+H2O）作为吸收剂，在模拟半贫液脱碳流程的基础上，对吸收剂配比、再生塔进塔温度和吸收剂循环量等关键工艺参数进行了敏感性分析。进一步，以系统总等量功最小为目标，依次对半贫液脱碳工艺进行参数和流程优化，得到了脱碳新工艺，并对比分析了新工艺与相同条件下经典醇胺法脱碳工艺的能耗变化规律。研究结果表明：运用新工艺脱碳后，净化气中CO2的摩尔分数为2.98%，满足《天然气》（GB 17820—2018）中一类天然气质量要求；新工艺消耗的系统等量功为15.03 MW，相比于同等条件下的半贫液脱碳工艺和经典醇胺法脱碳工艺分别降低了1.3%和5.5%。

Decarbonization Process Optimization and Energy Efficiency Analysis of Coal Underground Gasification Produced Gas

The mixture produced by underground coal gasification (UCG) is transported from underground to surface for gathering, transportation and treatment. In order to remove CO₂ from the mixture with low energy consumption and make the CO₂ mole fraction in the purified gas lower than 3%, sensitivity analysis, parameter optimization and process optimization of the decarbonization process of semi-lean liquid were carried out by Using Aspen HYSYS software. A new decarbonization process with energy saving and consumption reduction was proposed, and the energy efficiency of the new process was analyzed. Piperazine-activated methyl diethanolamine (PZ+MDEA+H₂O) was used as absorbent. On the basis of simulating the decarbonization process of semi-lean solution, sensitivity analysis was carried out on the key technological parameters such as the ratio of absorbent, inlet temperature of regeneration column and the amount of absorbent circulation. Furthermore, with the goal of minimizing the total equivalent work of the system, the parameters and processes of the semi-lean solution decarbonization process were optimized successively, and the new decarbonization process was obtained. The energy consumption change rule of the new process was compared with that of the classic alcohol-amine decarbonization process under the same conditions. The results show that the mole fraction of CO₂ in the purified gas is 2.98% after decarbonization with the new process, which meets the quality requirements of GB17820-2018 class I natural gas. The system equivalent work consumed by the new process is 15.03 MW, which is 1.3% and 5.5% lower than that of the semi-lean solution decarbonization process and the classic alcohol-amine decarbonization process under the same conditions.