基于深冷—膜分离的天然气蒸发气联合提氦流程模拟与效果对比  

Simulation and effect comparison of LNG-BOG combined helium extraction processes based on cryogenic-membrane separation

作　　者：张丽萍 巨永林[1] ZHANG Liping;JU Yonglin(Institute of Refrigeration and Cryogenics,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学制冷与低温工程研究所

出　　处：《天然气工业》2023年第8期170-182,共13页Natural Gas Industry

摘　　要：为保障氦气作为军工、医疗、科研等领域发展的重要应用要素,应充分利用含氦资源,从提氦技术及流程的改进、创新等方面实现低能耗、高效率的自主提氦。为此,以液化天然气蒸发气(LNG-BOG)为原料气,基于某一正在运行的BOG提氦液化工艺流程,提出了BOG深冷—膜分离—PSA法与深冷—两级膜分离法2种改进流程,采用Aspen Hysys建立了流程模型,分析了深冷塔塔板数等流程参数对关键设备的影响情况,最后综合分析了以上3种流程氦气产品浓度、回收率及能耗情况。研究结果表明:(1)当深冷塔总塔板数从3增加到4或5时,再沸器功率增加、冷凝器功率降低较为显著,而当总塔板数大于5时,塔板数变化对对冷凝器和再沸器功率、塔顶出口气体流量及氦浓度这4个指标的影响不大;(2)随着进料塔板位置下移,再沸器和冷凝器功率均下降,当进料位置接近冷凝器或再沸器时,功率受进料位置变化影响更大;(3)当级切或膜渗透侧浓度一定时,膜面积越大,对应膜渗透侧氦浓度或级切越大,且膜面积越小,渗透侧氦浓度受级切的影响越显著。结论认为,改进的深冷—膜分离—PSA法提氦流程和深冷—两级膜分离法提氦流程的氦气产品浓度分别可达99.9964%和99.9996%,回收率分别为99.57%和98.07%,能耗分别为6.6820 kWh/m^(3)和6.7863 kWh/m^(3),均较原BOG提氦液化流程有一定优势;深冷—膜分离—PSA法提氦流程综合提氦效果优于深冷—两级膜分离法提氦流程。In order to ensure the role of helium gas as an important application element in the fields of war industry,medical treatment and scientific research,it is necessary to make full use of helium bearing resources and realize independent helium extraction with low energy consumption and high efficiency based on the improvement and innovation of helium extraction technologies and processes.Taking the boil-off gas of liquefied natural gas(LNG-BOG)as the feed gas,this paper proposes two improved processes based on one running BOG helium extraction and liquefaction process,namely BOG cryogenic-membrane separation-PSA process and cryogenic-two-stage membrane separation process.Then,a process model is established by using Aspen Hysys,and the influences of the process parameters(e.g.the number of the trays of cryogenic column)on the key equipment are analyzed.Finally,the concentration,recovery rate and energy consumption of the helium gas product in the above three processes are comprehensively analyzed.And the following research results are obtained.First,when the total number of the trays of cryogenic column is increased from 3 to 4 or 5,the power of the reboiler increases while the power of the condenser decreases greatly.When the total number of the trays is over 5,its change has less influence on the powers of condenser and reboiler,the gas flow rate at the outlet of the column top and the helium concentration.Second,as the feed tray moves downwards,the powers of condenser and reboiler decrease.When the inlet point gets close to the condenser or the reboiler,its positional change has greater effect on the powers.Third,when the stage cut or the helium concentration on the permeable side the membrane is constant,the larger the membrane area is,the greater the helium concentration on the permeable side of the corresponding membrane or the stage cut is.With the decrease of the membrane area,the influence of the stage cut on the helium concentration on the permeable side increases.In conclusion,the cryogenic-membrane separ

关 键 词：液化天然气 蒸发气 氦气 深冷 膜分离 变压吸附 Aspen Hysys MATLAB 能耗 

分 类 号：TQ116.41[化学工程—无机化工] TQ028.8