水电盐联产海水淡化系统优化设计的研究

Seawater desalination has become an important technology to solve the scarce of fresh water resources in the world. But the high energy cost and environmental effect of the concentrated seawater are two defects, which is the main bottle-neck and restrict the popularization and application of desalination technology. So it is important to research the integration technology of desalination, power and salt production for decreasing energy cost and guaranteeing seawater resource to be continuously utilized. In this project, the process system engineering theory and method is adopted and the desalination, power and salt production are considered as a mutually supporting system. The thermodynamic model of seawater solution is presented to calculate the brine phase equilibrium and explore the precipitation laws of electrolyte salts. The separation system synthesis strategy and method of electrolyte salts is proposed. The optimization model of integration system of desalination, power and salt production is developed by investigating the transitive regulation and coupling features of the energy transfer and mass transfer for the integration system. Based on the T-H diagram, the energy utilization, energy conversion and the technological process are synthetically considered to achieve the best match of energy utilization for the integrated system. Subsequently, the energy integration strategy and the optimal design method of integrated system of desalination, power and salts production are obtained to guide the optimal design of desalination system.

海水淡化被公认为是解决淡水资源短缺的有效途径，但其存在能耗大、淡水成本高以及浓盐水排放对环境产生污染的缺陷，并已成为制约海水淡化技术推广应用的主要瓶颈。因此，开展水、电、盐联产的海水淡化技术研究对降低能耗、减少污染以及保障水资源可持续利用都具有重要意义。本课题运用过程系统工程的理论和方法，将水、电、盐的生产看作一个相互支持的系统，从热力学出发，研究浓盐水相平衡计算的热力学模型，探求电解质盐类的析出规律，提出复杂电解质体系盐类分离的过程综合策略和方法；分析海水淡化、发电和制盐过程能量传递、质量传递的规律和耦合特性，建立水电盐联产海水淡化集成系统的优化模型；以T-H图为基础，综合考虑能量的利用、转换环节和工艺过程，实现水电盐联产系统能量利用的最佳匹配，在此基础上提出水电盐联产海水淡化系统能量集成策略和优化设计方法，为海水淡化集成系统的设计提供理论指导。

本课题建立了水盐多电解质体系气液平衡、固液平衡的分析、测定方法，提出了两种活度系统模型，该模型不仅表达简单、所需参数少，而且具有较高的精度和预测性，为海水淡化浓盐水的分离提供的理论基础。研究了水盐体系的溶解动力学,建立了两个动力学模型，提出了水盐体系分离的图解综合法；开展了海水淡化能量回收器的研究，获得了结构参数、操作条件等参数对能量回收器效率的影响规律，为能量回收器的设计开发提供了技术支持；研究了污垢析晶过程的影响因素及变化规律，为海水淡化系统的设计、工艺条件优化以及过程控制提供了理论指导。开展了海水淡化系统及水电盐联产系统的优化研究，提出了逐步优化的能量综合策略，应用该策略开展了海水淡化系统、浓盐水分离过程综合、水电盐联产系统的优化设计和计划调度工作。