化工进展 ›› 2023, Vol. 42 ›› Issue (3): 1618-1628.DOI: 10.16085/j.issn.1000-6613.2022-0926

• 资源与环境化工 • 上一篇    下一篇

CO2捕集工艺中热再生气余热的PVDF/BN-OH平板复合膜回收特性

尚玉1,2(), 肖满1,2, 崔秋芳1,2, 涂特1,2, 晏水平1,2()   

  1. 1.华中农业大学工学院,湖北 武汉 430070
    2.农业农村部长江中下游农业装备重点实验室,湖北 武汉 430070
  • 收稿日期:2022-05-19 修回日期:2022-06-17 出版日期:2023-03-15 发布日期:2023-04-10
  • 通讯作者: 晏水平
  • 作者简介:尚玉(1997—),男,硕士研究生,研究方向为碳捕集过程中的余热回收利用。E-mail:shangyy_177@163.com
  • 基金资助:
    国家自然科学基金(51676080)

Recovery characteristics of PVDF/BN-OH flat composite membrane for waste heat of hot stripped gas in CO2 capture process

SHANG Yu1,2(), XIAO Man1,2, CUI Qiufang1,2, TU Te1,2, YAN Shuiping1,2()   

  1. 1.College of Engineering, Huazhong Agricultural University, Wuhan 430070, Hubei, China
    2.Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River, Ministry of Agriculture and Rural Affairs, Wuhan 430070, Hubei, China
  • Received:2022-05-19 Revised:2022-06-17 Online:2023-03-15 Published:2023-04-10
  • Contact: YAN Shuiping

摘要:

围绕CO2化学吸收工艺中热再生气的余热回收来开展研究。本文在CO2化学吸收系统的再生塔顶增设换热器,利用分流的冷富CO2吸收剂溶液来回收热再生气(CO2和水蒸气混合气体)中的余热,可降低CO2再生能耗,且余热回收性能越优,降耗效果越明显。采用膜换热器替代传统钢制换热器,利用余热回收过程中冷凝水的热质耦合传递,可强化余热回收性能。本文以聚偏氟乙烯(PVDF)为主体,添加羟基化氮化硼(BN-OH)共混改性,以聚酯纤维(PET)无纺布作为支撑层,制备了PVDF/BN-OH平板复合膜,并在乙醇胺(MEA)基富液分流化学吸收工艺中,探讨了复合膜的余热回收性能,同时与商业PVDF平板膜进行了对比。结果显示,与不添加BN-OH的M1膜相比,添加质量分数1%BN-OH的M3膜的平均孔径增加了约11.32%,而孔隙率仅下降了约7.14%,且依然保持亲水特性(水接触角为77.1°),同时热导率提高了约52.25%,说明M3膜具有强化热质耦合传递特性的潜能。与M1膜相比,在相同的操作参数条件下,M3膜的余热回收通量和热回收率最大可分别增加95.5%和31.6%。与具有更小厚度的商业化PVDF膜相比,M3膜的余热回收通量和热回收率最大可提高54.8%和9.6%,具有更优的余热回收特性。最后,通过拟合得出余热回收率与各试验因素之间的经验关系式。

关键词: 二氧化碳捕集, 传热, 传质, 跨膜冷凝器, 解吸

Abstract:

In this study, the waste heat recovery was concentrated from the hot stripped gas in CO2 chemical absorption process. A heat exchanger could be added on the top of CO2 stripper in the CO2 chemical absorption system to reduce the CO2 regeneration energy consumption, which was fulfilled by recovering the waste heat from the stripped gas (i.e., the mixture of water vapor and CO2) using the bypassed cold CO2-rich solvent in the heat exchanger. Generally, a better waste heat recovery performance leaded to a low CO2 regeneration energy consumption. The waste heat recovery performance could be enhanced by adopting the novel membrane heat exchanger to replace the traditional steel heat exchanger because of the coupled heat and condensate transfer in the membrane heat exchanger. A PVDF/BN-OH flat composite membrane was prepared through the blend modification method using polyvinylidene fluoride (PVDF) and hydroxylated boron nitride (BN-OH). In this composite membrane, the polyester fiber (PET) non-woven fabrics was used as the support layer. The waste heat recovery performance was experimented by using the prepared composite membrane in the monoethanolamine (MEA)-based rich-split process. Additionally, the commercial PVDF membrane was also adopted as the control. Compared with the prepared composite membrane without adding BN-OH (i.e., M1 membrane), the membrane adding 1% BN-OH (i.e., M3 membrane) achieved a higher average pore size by about 11.32%, a relatively lower porosity by about 7.14% and a higher conductivity by about 52.25%. Notably, M3 membrane still maintained the hydrophilicity with a water contact angle of 77.1°. Therefore, M3 membrane may have the potential to enhance the coupled mass and heat transfer performance. Under the same operation conditions, M3 membrane could obtain a waste heat recovery flux up to 95.5% higher than M1, and a heat recovery ratio up to 31.6% higher than those of M1 membrane. Compared to the commercial PVDF membrane with a smaller thickness, M3 membrane still had a maximum 54.8% higher waste heat recovery flux and 9.6% higher heat recovery ratio, suggesting the better waste heat recovery performance of M3 membrane. Finally, the empirical correlations between the waste heat recovery ratio and key operation parameters were proposed, which showed a high accuracy.

Key words: CO2 capture, heat transfer, mass transfer, transport membrane condenser, desorption

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