闭式热泵膜蒸馏电镀废水系统的热力性能分析

Thermal performance analysis of closed heat pump membrane distillation electroplating wastewater system

为了可以对电镀废水中的金属盐类和水实现高效的资源化回收,且相较于常规蒸发法处理废水更加节能,提出了闭式热泵膜蒸馏电镀废水系统。该系统将膜蒸馏技术与闭式热泵进行耦合,基于质量和能量守恒原理编写膜蒸馏自定义模型,在与实验数据进行对比验证后,通过Aspen Plus仿真平台建立流程来模拟工作情况。通过改变关键操作参数,得到以下结果:进料速度会引起系统功耗的大幅度增加而对于膜蒸馏的潜热的影响较小,因此进料速度对于系统造水比(GOR)影响最大。蒸发温度对于系统的能效比(COP)有着较大的影响,且COP随着蒸发温度的提升而上升,在不同蒸发温度下,系统GOR的下降趋势随进料温度升高先缓再陡。进料浓度对于系统产量比(YRO)有着重要作用,YRO随进料浓度上升而上升;当处在较低的蒸发温度下,不同浓度下的GOR在低进料温度时值较为接近。

Electroplating wastewater is one of the extremely harmful sewages, which must be pretreated before being discharged. The evaporation method can be used to pretreat the electroplating waste water and recover it waste resources, but its shortcomings of high energy consumption limit its use. Through coupling a closed heat pump cycle and the membrane distillation process, a novel electroplating wastewater treatment system is proposed in this work to pretreat the electroplating wastewater, the metal salts is recovered and the energy consumption is low. Based on the Aspen Plus simulation platform, the proposed system model is built. After verifying the key components model with the experimental data, the key operating parameters influences on the overall thermodynamic performance of the system have been investigated, and the following results are obtained. Increasing the feed rate caused a substantial increase in the power consumption of the system, but impacted little on the latent heat of the distillation membrane, so the feed rate had the greatest impact on the gain water ratio(GOR) of the system. Due to the increase in processing flow, the yield ratio(YRO) of the system increased slightly, but the feed rate showed almost no effect on the coefficient of performance(COP) of the system.The evaporation temperature had a great influence on the COP of the system, and the COP increased with the increase of the evaporation temperature. The downward trend of the system GOR decreased slowly and then steeply with the feed temperature increase. The GOR of the system was affected by the evaporation temperature and increased as the evaporation temperature was increased. YRO was affected by the combination of evaporation temperature and system power consumption, and showed different trends at high and low feed temperatures. The feed concentration played an important role in the YRO. YRO increased as the feed concentration was increased. The GOR at different concentrations was closer at the low feed temperature. Therefore, these results can provide significant references for the further implementation and optimization of the proposed system.