面向烟道气脱碳的集成微孔膜组件内吸收/解吸过程耦合与传质强化研究

High efficiency capture of CO2 from flue gas of coal-fired power plant is an important route for clean and efficient coal utilization. Currently applied chemical absorption method has advantages such as strong capability of CO2 removal plus high purification degree. Unfortunately at the same time this method suffers from low absorption/desorption efficiency, high energy consumption and investment requirement. This urges to put the development of a better efficient and energy-saving CO2 removal technology on the menu. In view of this, this project will aim at investigation of coupled absorption/desorption behavior of CO2 in an integrated membrane module (absorption and desorption can be realized in single module), and mass transfer/ coupling principle will also be systematically studied. The main research contents include: (1) PEEK and PEI blend will be co-melting spun first, and then through selective removal of PEI by chemical reaction micro-porous structure of PEEK membrane will be formed and tuned to be suitable for absorption/desorption process; (2) CO2 permeation through absorption porous fiber/absorbent layer/desorption porous fiber in the integrated membrane module to realize a coupled absorption/desorption effect will be systematically studied and the mass transfer model will be established; (3) The optimized match between coupled absorption/desorption behavior and process parameters/mass transfer path will be studied, and solvent capability will also be purposely improved. As a result effective manipulation and mass transfer intensification for CO2 absorption/desorption process will be realized.

燃煤电厂烟道气中CO2的高效捕集是煤炭清洁高效利用的重要途径。采用化学吸收法具有脱碳能力强、净化度高等优点，但该过程固有的吸收/解吸效率低、能耗及成本高等缺点尚未得到有效解决，因此研究开发节能高效的新型脱碳过程具有重要意义。鉴于此，本项目拟通过考察烟道气中CO2在集成微孔膜组件（单组件内同步完成CO2的吸收/解吸）内的吸收/解吸耦合行为，对该过程的传质规律进行系统研究。研究内容主要包括：（1）聚醚醚酮与聚醚酰亚胺共混熔融纺丝，再通过选择性反应去除聚醚酰亚胺以形成并调控膜的微孔结构，使之适于吸收/解吸过程；（2）探索集成微孔膜组件内CO2通过吸收微孔膜/吸收剂层/解吸微孔膜间的传递实现吸收/解吸耦合过程的传递特性与建立传质模型；（3）通过集成微孔膜组件内CO2的吸收/解吸行为与工艺参数、传质通道之间的优化匹配以强化传质，辅以吸收剂性能调控，实现对烟道气中CO2的选择性高效脱除。

燃煤电厂烟道气是我国温室气体CO2排放的主源之一，开发出节能高效的烟道气脱碳技术是关系到我国双碳目标顺利实施的关键所在。烟道气压力低且所含的CO2浓度低，使得烟道气脱碳成为极具挑战性的技术难题。本项目采用微孔膜与吸收过程耦合技术进行烟道气脱碳研究，通过微孔膜为气液两相提供更多传质面积，以期大幅度提高吸收效率。首先采用PEEK/PEI双组分共融，然后PEI单组份化学去除的膜内成孔方法，在国内率先开发出适用于膜吸收过程的纳米级聚醚醚酮微孔膜，优化纺丝条件下PEEK微孔膜的气体渗透速率在室温下可达到～2000.0 GPU；同时其纳米级孔径（～20 nm)、超细直径(<0.5 mm)以及表面疏水化改性手段，为PEEK微孔膜应用于膜吸收法烟道气脱碳过程提供了较好的技术条件。采用所制备的纳米级聚醚醚酮微孔膜结合不同吸收剂，通过膜吸收对烟道气中CO2进行了脱除研究：当采用80%[Bmim][DCA]-20%PAMAM以物理吸收模式对烟道气进行脱碳时，受限于较低的CO2分压，吸收过程在优化条件下可以实现5.8%的放空气CO2含量及61.4%的CO2脱除率；当采用MDEA吸收剂促进CO2吸收后，膜吸收过程可在优化条件下实现对烟道气90%以上CO2脱除率，吸收剂再生后解吸气体中CO2浓度超过95%；采用水作为吸收剂以逆流模式开展膜吸收烟道气脱碳，优化条件下脱碳率可稳定在95%以上；同时采用自开发的聚酰亚胺膜对烟道气脱碳进行了研究，在优化运行条件下可以实现70%以上的CO2脱除率及40%以上的CO2富集浓度。对比两种脱碳技术，膜分离法对烟道气压力要求更高，其分离过程无需吸收剂再生；膜吸收法在脱碳效果方面具备更加明显的优势。从拓展PEEK膜的应用领域出发，开展了基于该膜的膜蒸馏过程研究，结果证明其可以稳定高效地应用于高含盐量水的处理。以上工作为我国烟道气脱碳领域提供技术储备与支撑，有利于助力我国双碳目标的顺利实现。