降膜蒸发传热实验研究及多效蒸发系统流程模拟

发布时间：2018-05-15 23:30

本文选题：降膜蒸发 + 液膜流动　；参考：《华东理工大学》2016年硕士论文

【摘要】：立式降膜蒸发器因其较高的传热系数,较小的传热温差等特点,获得广泛的应用。本文基于节能减排的目的,旨在开发多孔管高效降膜蒸发器。本实验的最小容许降液流率为35kg/h,设计的锯齿型和锥型布膜器都能有效成膜,减小不均匀系数芎,为传热实验提供保证。开发内烧结型表面多孔管降膜蒸发器,在热通量q=13-90kW·m-2,传热温差ΔT=2.87-9.5℃,液体Reynolds数ReL=4500-15000范围内分别以纯水和盐水为介质进行实验,并与螺旋平纹管和三头波纹管对比。结果表明：多孔管传热温差约为光滑管的1/2,降膜传热系数比光滑管提高约100%,而三头波纹管仅提高约17%,螺旋平纹管并没有特别明显的强化效果。多孔管在3%质量分数的盐水中依然保持高效的传热性能,能够应用于多效蒸发系统,实现低温差传热,减小传热面积。采用Aspen Plus软件模拟多效蒸发系统,结果表明：相比其他进料方式,平流进料方式具有较高的造水比,回收比和浓缩比,蒸发浓缩性能优势显著。对于平流进料方式,抽取部分二次蒸汽预热进口物料,优化后的系统造水比明显提高。
[Abstract]:The vertical falling film evaporator is widely used because of its high heat transfer coefficient and small heat transfer temperature difference. Based on the purpose of energy saving and emission reduction, this paper aims at developing a high efficiency falling film evaporator with porous tube. The minimum allowable drop flow rate of this experiment is 35kg/h. The designed sawtooth and cone type film distributor can effectively form the film and reduce the inhomogeneous system. In order to provide guarantee for the heat transfer experiment, the internal porous tube falling film evaporator with internal sintered surface was developed to experiment with pure water and brine in the range of heat flux q=13-90kW m-2, heat transfer temperature difference of T=2.87-9.5 C, Reynolds number ReL=4500-15000 of liquid, and compared with spiral plain tube and three bellows. For the 1/2 of the smooth tube, the heat transfer coefficient of the falling film is about 100% higher than that of the smooth tube, and the three bellows only increase by about 17%. The spiral plain tube has no special strengthening effect. The porous tube still maintains the high efficiency heat transfer performance in the salt water of 3% mass fraction. It can be applied to the multi effect evaporation system to realize the heat transfer of low temperature difference and reduce the transmission. The Aspen Plus software is used to simulate the multi effect evaporation system. The results show that compared with the other feeding methods, the flat flow feeding method has a higher water ratio, the recovery ratio and the concentration ratio, and the evaporation concentration performance advantage is significant. For the flat flow feed method, the two steam preheated imported materials are extracted and the optimized system water making ratio is significantly raised. High.

【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ021.3

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