热泵多效膜蒸馏系统的研究

发布时间：2018-05-24 06:49

  本文选题：膜蒸馏 + 热泵　； 参考：《天津科技大学》2016年硕士论文

【摘要】：膜蒸馏技术是一项将蒸馏与膜分离技术相结合的新技术,具有常压中低温操作、设备简单等优点,在中高浓度废水处理、超纯水制备、热敏性料液浓缩等方面均可广泛应用。膜蒸馏过程需要外界同时提供冷热能对其冷凝液侧冷却、料液侧加热,基于热泵系统可以同时提供冷热能的特点,将膜蒸馏技术与热泵相结合,为解决单效膜蒸馏系统能耗大的问题,本文将热泵与多效膜蒸馏技术集合为热泵多效膜蒸馏系统,并对其性能随不同参数的变化规律进行研究。针对四种膜蒸馏技术:直接接触式膜蒸馏(DCMD)、气隙式膜蒸馏(AGMD)、气扫式膜蒸馏(SGMD)、真空式膜蒸馏(VMD)。建立了各自的物理模型,给出了膜通量和造水比的理论方程,并以膜通量、造水比为评价指标,对其随料液温度、膜冷热侧温差、膜孔径、膜壁厚度的变化规律进行了计算对比,结果表明,相同条件下VMD膜通量和造水比最高,但投资偏大;AGMD和SGMD造水比较高但膜通量偏低;DCMD结构简单,膜通量较大、适宜条件下造水比也较高,具有较强的综合优势。以DCMD为基础,构建了热泵两效膜蒸馏系统的物理模型和数学模型,编制了计算软件,对产水率、造水比、热泵制热量和热泵制热系数等性能指标随料液温度、膜组件膜面积和液体流速的变化规律进行了计算研究。结果表明,在一定范围内,系统在料液温度较低时,产水率、造水比等随着料液温度近似呈线性增大,当料液温度达到70℃后,产水率、造水比等继续增大,但增幅减小;一定范围内,系统产水率、造水比等随着膜面积的增大而增大,但增幅越来越小;一定范围内,系统在料液温度较高、膜面积较大时运行最好。以上述工作为指导,以热敏料液低温浓缩为背景,研制了热泵两效膜蒸馏实验装置,研究了系统工作时的工况调整方法和性能指标变化规律,结果表明,采用辅冷器可显著改进装置的工况调整效果,产水率、造水比、热泵制热量和热泵制热系数等变化规律与理论模型计算结果基本一致,低温工况热泵性能良好,但膜组件的造水比和膜通量较低。
[Abstract]:Membrane distillation is a new technology which combines distillation with membrane separation technology. It has the advantages of normal pressure, medium and low temperature operation, simple equipment and so on. It can be widely used in the treatment of medium and high concentration wastewater, the preparation of ultra-pure water, and the concentration of thermosensitive material liquid. In the process of membrane distillation, the heat and cold energy is provided simultaneously to cool the condensate side and the material side is heated. Based on the characteristics that the heat pump system can provide the heat and cold energy simultaneously, the membrane distillation technology is combined with the heat pump. In order to solve the problem of high energy consumption of single-effect membrane distillation system, the heat pump and multi-effect membrane distillation technology are combined into heat pump multi-effect membrane distillation system in this paper, and its performance changes with different parameters are studied. There are four kinds of membrane distillation technologies: direct contact membrane distillation, air gap membrane distillation, air sweep membrane distillation and vacuum membrane distillation. Their physical models were established and the theoretical equations of membrane flux and water ratio were given. The membrane flux and the ratio of water to water were taken as the evaluation indexes, and the membrane pore size was determined with the temperature of the liquid, the temperature difference of the cold and hot side of the membrane, and the pore size of the membrane. The results show that the membrane flux and water ratio of VMD are the highest under the same conditions, but the investment is higher than that of SGMD, but the structure of membrane flux is simple and the flux of membrane is larger. The ratio of water to water is also high under suitable conditions, and has strong comprehensive advantages. Based on DCMD, the physical model and mathematical model of two-effect membrane distillation system of heat pump are constructed. The calculation software is developed to calculate the performance of heat pump, such as water yield, ratio of water to water, heat capacity of heat pump and heat coefficient of heat pump, etc. The changes of membrane area and liquid velocity of membrane assembly were calculated and studied. The results show that, in a certain range, the water yield and the ratio of water to water increase linearly with the temperature of the feed liquid at a lower temperature. When the temperature reaches 70 鈩，

本文编号：1928098