关键词: 反渗透, 优化, 全流程, 变参数, 脱盐, 膜

Abstract: It is of significance to reduce the total operational cost of seawater reverse osmosis (SWRO) system through the system engineering approach. In this work, based on the formulation of the full flowsheet model including process equations and total operational cost equation, an operational optimization strategy with time varying parameters was proposed. First, according to the solution-diffusion principle and variable parameter characteristics of the whole system, the RO process model, storage tank model and related parameter equations were established. Then, based on full flowsheet of SWRO process and composition of operational cost, the model of total operational cost was obtained as well as the full flow sheet's cost per cubic meter water. The optimization problem was formulated with the objective function to minimize total operational cost, and with the equations and various bound constraints. And then simultaneous approach wherein the differential and algebraic variables were fully discretized leading to a large-scale nonlinear programming (NLP) problem was used for the solution technique, and interior point optimizer (IPOPT) was used as the large scale solver. A case study was then performed to demonstrate the effect of the proposed strategy; computing results demonstrated that the proposed strategy could largely reduce the total operational cost of the SWRO system. Through solutions of the optimization problem, the optimal operating pressure and flowrate curve as well as the key performance profiles were obtained under different environmental parameters. This work is of significance to improve the performance and reduce the operational cost of the SWRO system.

Key words: RO, optimization, full flowsheet, time varying parameters, desalination, membranes