关键词: 半贫液工艺, 天然气脱碳, 贫液, 半贫液, 富液

Abstract: 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.

Key words: semi-lean solution process, natural gas decarburization, lean liquid, semi-lean liquid, rich liquid