高回收率低温多效工艺研究

发布时间：2018-04-21 06:56

本文选题：海水淡化 + 低温多效　；参考：《天津大学》2016年硕士论文

【摘要】：针对日产2.5万吨高回收率低温多效系统设计了四效平流、六效逆流、十效逆流和十四效逆流四种不同的工艺,分别从物料守衡、能量守衡和热量传递方面对工艺中的蒸发器、冷凝器、蒸汽喷射器以及闪蒸罐等设备建立了数学模型。经过模拟计算四种工艺的造水比分别为7.19、7.78、12.02和16.8,单位蒸发面积分别为399.7、275、420.68和674.13m~2/(kg/s),动力蒸汽的用量分别为144.84、133.83、86.63和61.99t/h。效数增加时造水比逐渐增大,动力蒸汽用量降低。在产水量一定的条件下,十四效逆流造水比最大,所需要的动力蒸汽的量最少,但同时其所需要的单位蒸发面积最大。有效能损失计算发现,四种不同的工艺的有效能的利用率均低于20%,其中蒸汽喷射器的嗾损失占有较大的比例。另外本文对操作条件对工艺性能的影响作了研究,发现工艺参数中抽汽位置、浓缩比、换热温差、进料海水盐度等因素对工艺性能的影响较大。随着抽汽位置的后移,造水比呈现出先增大后减小的规律。六效逆流时在第五效为最佳抽汽位置,十效逆流时第八效为最佳抽汽位置,十四效逆流时第十二效为最佳抽汽位置;动力蒸汽压力变大时造水比提高,单位冷却海水量降低;产品水量增大时,造水比保持不变,单位蒸发面积和动力蒸汽量随之等比例增加;进料海水盐度增大时,单位换热面积也会增大;当传热总温差增大时,动力蒸汽量增大,造水比降低,单位换热面积减少;浓缩比增大时,加热蒸汽量、抽取蒸汽量和动力蒸汽量都减少,造水比增大,单位冷却海水量增大,单位换热面积增大,进料海水量减少。研究结果可以对实际生产和过程优化以及低温多效工艺的选择提供一定的理论依据。
[Abstract]:Four different processes of four-effect advection, six-effect countercurrent, 10-effect countercurrent and 14-effect countercurrent are designed for the 25000 ton per day high recovery and low temperature multi-effect system. The evaporators in the process are operated from the aspects of material balance, energy balance and heat transfer, respectively. The mathematical model of condenser, steam ejector and flash tank is established. The water ratio of the four processes is 7.19 ~ 7.781.02 and 16.8respectively, the evaporation area is 399.7275420.68 and 674.13mg / kg 路s ~ (-1) / s ~ (-1), and the power steam consumption is 144.84133.83 ~ 86.63 and 61.99 t / h, respectively. With the increase of validity, the ratio of water to water gradually increased and the amount of dynamic steam decreased. Under the condition of constant water yield, the 14 effect countercurrent water ratio is the largest, the amount of power steam needed is the least, but the unit evaporation area is the largest at the same time. The effective loss calculation shows that the effective utilization ratio of the four different processes is lower than 20 percent, and the steam ejector has a large proportion of the loss of steam ejector. In addition, the effect of operating conditions on the process performance is studied. It is found that the extraction position, concentration ratio, heat transfer temperature difference and salinity of seawater feed have great influence on the process performance. With the backward shift of the extraction position, the water ratio increases first and then decreases. The best extraction position is in the fifth effect, the eighth effect in the ten effect countercurrent, and the optimum extraction position in the fourteen effect countercurrent, the water production ratio increases with the increase of the power steam pressure, and the unit cooling seawater volume decreases. When the water quantity of the product increases, the ratio of water to water remains constant, and the ratio of unit evaporation area to power steam quantity increases, and the unit heat exchange area also increases when the salinity of seawater is increased, and when the total heat transfer temperature difference increases, the power steam quantity increases. With the increase of concentration ratio, the amount of heating steam, the quantity of extraction steam and the quantity of dynamic steam decrease, the ratio of water to water increases, the amount of unit cooling seawater increases, the unit heat exchange area increases, and the amount of seawater in feed decreases. The results can provide some theoretical basis for practical production and process optimization as well as the selection of low temperature multi-effect process.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P747

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