ANALYSIS AND OPTIMIZATION OF A REVERSE OSMOSIS WATER PURIFICATION SYSTEM .2. OPTIMIZATION

A mathematical model of a reverse osmosis water purification system that can be used in process optimization studies and cost equations that relate the capital and operating costs to the design variables is developed in Part I of this work. In this part, the model is used to determine design and operating variables of the system, which minimize the cost of water production. Several three multistage reverse osmosis systems are considered. They are a multistage operation without the use of a flow-work exchanger and with a variable membrane area at each stage (System 1), that with equal membrane area at each stage (System 2), and a multistage operation with the use of a flow-work exchanger and with variable membrane area at each stage (System 3). In the optimization study, the recirculation rate in each stage, the brine composition leaving each stage, the ratio of membrane area to feed at each stage, and the operating pressure in each stage are controlled to arrive at a minimum water production cost. © 1969.