中文摘要：

膜污染是导致反渗透海水淡化（seawater reverse osmosis,SWRO）系统操作成本增加和产水性能下降的重要因素。为了降低系统运行操作成本,本文针对卷式SWRO系统提出了一种新的膜清洗与更换策略优化方法。首先,根据反渗透和膜污染过程机理建立了膜污染情况下的SWRO系统性能模型;然后将生产过程中的总操作费用与膜清洗和更换规划联系起来,建立了以系统日均操作费用最低为目标、以膜清洗次数、膜清洗和更换时间等为寻优变量、以开放式方程模型为约束的优化命题,并通过联立求解等技术使得原本复杂的优化命题可快速方便地求解;在此基础上对SWRO系统进行了实例研究和分析。优化求解结果表明：（1）本优化策略可以大幅降低系统操作费用,并同时获得最佳膜清洗和更换时间以及膜清洗次数;（2）进料海水温度对最优膜清洗和更换策略影响很大,固定周期的膜更换策略并不合适。另外本优化方法还可得到不同条件下最优操作费用组成、以及最优目标下最优操作压力和操作流量曲线等信息,对优化SWRO系统运行和深入分析系统内部状态变化具有重要意义。

英文摘要：

Membrane fouling is a key factor for the increase of operation cost and the decrease of product performance of the seawater reverse osmosis （SWRO） system. In this work, a strategy of new membrane cleaning and replacing schedule for spiral-wound SWRO system was proposed to reduce the operation cost. First, according to the solution-diffusion principle and membrane fouling characteristics, the SWRO performance model considering membrane fouling was established. Then, the total operation cost was integrated with membrane cleaning and replacing schedule to establish the optimization problem, which set minimizing the daily operation cost of the system as an objective, membrane cleaning frequency, cleaning time and replacing time as optimization variables, and the open equations as constraints. And the finite-element-based simultaneous method was applied to solve the complex optimization problem efficiently. After the case study and analysis of the SWRO system, the optimization results showed that the proposed optimization strategy can significantly reduce the operational cost, while obtaining the optimal membrane cleaning frequency and the cleaning and replacing time. It was found that the feed seawater temperature had an important effect on the membrane cleaning and replacing schedule as well as total operational cost, and thus it was not suitable to fix the membrane replacement interval. In addition, the proposed method can obtain the profile of optimal operational pressure and flow rate as well as internal status and performance of the system under different operation conditions, which was of great significance to optimize the operation of the system and the further study on the inner status of the system.