两级膜法海淡系统的能耗及回收率模拟研究

Investigation of Optimization Strategies on Energy Consumption Reduction and Water Recovery Enhancement in Design of a Two-phases SWRO Desalination System

膜法海水淡化系统设计的关键是有效降低系统能耗并提高回收率。试验建立了两级膜法海水淡化系统的数学模型,通过对该模型的计算分析,研究了能量回收装置、二级反渗透浓水回流措施及一、二级反渗透工况运行参数对系统比能耗和回收率的影响。结果表明,采用能量回收装置回收一级反渗透高压浓盐水的高压能极大降低系统比能耗,采取二级反渗透浓水回流至一级反渗透进水增压泵前的措施可有效提高系统回收率;当设置能量回收装置并采取回流措施时,系统比能耗的低值范围主要分布在一级反渗透回收率的低值区和二级反渗透回收率的高值区,而系统回收率的高值范围主要分布在一、二级反渗透回收率的高值区。当开展膜法海淡系统设计时,可采用提出的数模分析方法,在综合评判系统比能耗和系统回收率的基础上,确定系统优化策略,以求膜法海淡生产经营效益的最大化。

The attention to SWRO desalination system designing is always focused on the energy consumption reduction and the water recovery increase. This study established a mathematical model for a two-phases SWRO desalination system. The computational analysis of the mathematical model was carried out to estimate the effects of the energy recovery device, the brine circulation of secondary reverse osmosis, and the operating parameters of the primary and secondary reverse osmosis on the general specific energy consumption and water recovery. The results indicated that the general specific energy consumption was significantly decreased when utilizing an energy recovery device to recover the high pressure energy from the brine of the primary reverse osmosis. The general water recovery was increased as well when cir- culating the brine from the secondary reverse osmosis to the entrance of the primary reverse osmosis. Low general specific energy consumption was obtained at the low water recovery phase of the primary reverse osmosis and the high water recovery phase of the secondary reverse osmosis. High general water recovery was obtained at the high water recovery phases of both the primary and the secondary reverse osmosis. When designing the SWRO desalination system, it is recommended to utilize the proposed mathematical model to estimate various types of SWRO desalination system strategies. The balance of the general specific energy consumption and water recovery can be incorporated into the preparation of the optimization strategies of SWRO desalination system, to achieve the best benefit in production and operation.