哌嗪活化N-甲基二乙醇胺半贫液脱碳工艺配方优选及参数优化

哌嗪(PZ)活化N-甲基二乙醇胺(MDEA)半贫液脱碳工艺是高含碳天然气预处理能耗高问题的解决途径之一。针对某天然气处理陆上终端采用的PZ活化MDEA半贫液脱碳工艺(设计天然气处理能力为8×109 m3/a，原料气中CO2体积分数为35%)，采用吸收再生实验方法对系统中存在的贫液、半贫液吸收CO2性能以及富液解吸CO2性能进行考察，优选适用于半贫液脱碳工艺的胺液配方，并采用HYSYS软件建立半贫液工艺模型，对筛选出较优工艺配方下的工艺参数进行优化。结果表明：随着总胺浓度增加，贫液、半贫液吸收CO2性能及富液解吸CO2性能先增加后减小，较优总胺质量分数为40%；总胺质量分数一定时，随PZ添加量增加，贫液及半贫液吸收CO2性能先增加后减小，解吸CO2相对再生能耗先增加后降低，PZ较优添加质量分数为3%，之后随着PZ添加量的增加，解吸CO2相对再生能耗又缓慢升高，较优胺液配比(质量分数)为37%MDEA+3%PZ；模拟得到较优工艺参数为再沸器温度386.15 K，贫液吸收温度323.15 K，贫液循环量253 m3/h、半贫液循环量1147 m3/h。

Formula and Process and Parameters Optimization of PZ-Activated MDEA Semi-Lean Solution Decarburization Process

Piperazine (PZ) activated N-methyldiethanolamine(MDEA) semi-lean solution decarburization process is one of the solutions to the problem of high energy consumption in high carbon natural gas pretreatment. Here, aiming at the semi-lean solution decarburization process (Designed capacity of natural gas is 8×109 m3/a, and the CO2 volume fraction in raw gas is 35%) was used at a natural gas treatment onshore terminal, the absorption and regeneration experiments were carried out to investigate the CO2 absorption performance of lean and semi-lean solution, and the desorption performance of rich solution. Subsequently, the amine solution formula for the semi-lean liquid decarburization process was optimized. Lastly, the semi-lean process model was established by using HYSYS software, in order to optimize the process parameters under the optimal process formulation. The results show that with the increase of total amine concentration, the CO2 absorption and desorption performance of lean and semi-lean liquids increases first and then decreases, and the optimal total amine mass fraction is 40%. When the total amine concentration is constant, the absorption performance of lean and semi-lean liquids increases first and then decreases, and the relative regeneration energy consumption from rich liquor increases first and then decreases, with a optimum dosage of 3%. With the increase of PZ addition, the relative regeneration energy consumption increases slowly, and the optimum ammonia liquid ratio (mass fraction) is 37% MDEA+3% PZ. Lastly, the optimum process parameters are obtained by the simulation: Reboiler temperature is 386.15 K, lean liquid absorption temperature is 323.15 K, lean liquid circulation volume is 253 m3/h and semi-lean liquid circulation volume is 1147 m3/h.