Abstract:

Biogas and the associated gas produced by CO₂ flooding oil recovery contain large amount of CO₂. In order to reduce the energy consumption of high CO₂-content natural gas liquefaction process, a natural gas liquefaction system that uses activated methyldiethanolamine (MDEA) to remove CO₂ is proposed, and the waste heat of exhaust from the gas turbine driving the compressors in the liquefaction plant is utilized in the regeneration process of the absorbent. The HYSYS software is used to simulate the system and analyze the key parameters of the decarbonization process. The results show that waste heat of gas turbine exhaust can provide all the heat load for the regeneration system with a CO₂ content not exceeding 10% in feed gas. Even if the CO₂ is up to 30%, it can also provide nearly 50% regenerative heat load. Furthermore, when the CO₂ content in feed gas is 1% — 30%, the specific power consumption of the system is 0.577 — 0.611 kW·h/kg.

Key words: carbon dioxide, liquefaction, natural gas, activated MDEA, waste heat utilization

摘要：

沼气以及CO₂驱采油的伴生气中都含有大量的CO₂。为降低高含CO₂天然气液化的能耗，提出了活化甲基二乙醇胺（MDEA）法脱除CO₂的天然气液化系统，将液化厂中驱动压缩机的燃气轮机烟气余热用于吸收剂的再生过程，实现能耗的降低。采用HYSYS软件对系统进行了模拟研究并对脱碳过程的关键参数进行了分析。结果表明，CO₂含量不超过10%时，脱碳再生的热耗可全部由烟气余热提供，CO₂含量为30%时，烟气余热可提供接近50%的再生热耗；CO₂含量为1%～30%时，系统的比功耗为0.577～0.611 kW·h/kg。

关键词: CO₂, 液化, 天然气, 活化甲基二乙醇胺, 余热利用