反渗透海水淡化系统中膜组件的清洗策略

Cleaning strategy of membrane modules in reverse osmosis seawater desalination system

反渗透海水淡化法中膜组件的定期清洗是防治膜污染的主要措施之一.膜清洗可将膜表面的污染物去除,达到恢复透水量的目的.在保证产水量的情况下,选择恰当的清洗策略和清洗时机可使清洗次数最合理,清洗费用最低.以规划期内总操作费用最小为目标,提出了新的污染模型,给出了清洗的判据,将清洗策略问题表达为一个混合整数非线性规划(MINLP).对一个实例进行计算,给出了该例中的反渗透系统在5年规划期内的最优清洗策略和清洗时机.结果证明这种数学规划方法对于寿命为3～5年的膜组件的清洗维护是有效的.

In the reverse osmosis desalination process, regular cleaning is one of main measures to prevent and control membrane fouling and scaling. Cleaning can eliminate surface contamination of membrane and recover the water flux. On condition that the water production is ensured, optimal cleaning frequency and minimum cleaning cost could be obtained by choosing the appropriate cleaning strategy and time. This paper presents a new fouling model and the criterion of cleaning. The mathematical formulation of the optimum design is a mixed-integer non-linear programming (MINLP) problem, which targets at the minimum total operation cost during the whole projection period. One example is solved and the corresponding optimal time and cleaning strategy is obtained during the five-year projection period, which illustrates the effectiveness of the new method for the optimal maintenance of the 3-5 years life-span membrane modules.