低温多效海水淡化系统模拟分析-化学工程专业论文.docxVIP

摘 要 低温多效海水淡化技术可高效利用低品位热源，对预处理要求低，生产的淡 水水质高，同时因低温运行减少了系统结垢和腐蚀的风险，作为主要海水淡化方 法之一，得到越来越广泛的应用。随着低温多效海水淡化工程的建设，对其过程 的模拟分析与设计方法就变得十分必要。本文针对平流和逆流流程低温多效蒸馏 海水淡化系统，建立蒸发器等相关物料及能量等数学模型，构建了分析及设计方 法，为低温多效海水淡化工程应用奠定了基础。 论文建立了海水相关物性参数关系式，并根据工程实际数据回归得到蒸汽压 缩喷射器的相关模型，从整体和各组成部分建立了物料平衡方程、能量平衡方程 和传热方程等数学模型，为解决高度非线性方程而采用牛顿迭代法，借助 MATLAB 编程软件，编制并确定系统模拟计算的源程序。并通过调整系统操作 变量，如系统效数、第一效加热蒸汽温度、进料海水盐度等，得到系统各性能参 数的变化规律。进一步将模型用于 25000t/d 逆流低温多效蒸馏海水淡化系统， 10000t/d 平流低温多效蒸馏海水淡化系统，计算结果和工程实际吻合。 从系统有效能出发，分别建立了系统?模型、?损失模型以及能量品位相关 模型。通过对 10000t/d 4 效平流流程和 25000t/d 14 效逆流流程多效蒸馏海水淡 化系统进行有效能分析，得出两系统的?利用率均不足 20%；系统最大?损失均 发生于蒸汽压缩喷射器处，分别占系统总?损失的 49%和 47%；系统各效?损 失基本相当。采用图像?分析法（Exergy Utilization Diagram, EUD），将系统各 部分?损失情况用图形的形式直观表现出来。为系统降低能耗指明了方向，有利 于进一步降低海水淡化成本。 关键词：低温多效蒸馏，海水淡化，模拟分析，图像?分析 ABSTRACT Low-Temperature Multi-effect Distillation (LT-MED) is one of the main desalination methods. In LT-MED system, low-grade heat can be effectively utilized, requirements on the pretreatment of the feed water are easy to be satisfiyied, and the produced freshwater is of good quality. Besides, the problems of scaling and fouling are greatly alleviated because of the low operating temperature, therefore, LT-MED are being applied more and more widely. With a large number of LT-MED projects being under construction, it is indispensable to develop approaches to design, simulate, and analyse the system. In this paper, with the parallel feed and counter-current feed LT-MED systems as the subject, the relevant relations of physical properties as well as various mathematical models were been established, and the means of analysis and simulation were built, which laid a foundation for the engineering application of LT-MED technology. In the paper, the corresponding relations of seawater physical properties were erected, and according to the field datas, the regression equations of steam jet-ejector were confirmed. Meanwhile, as for the whole system and each subsystem, the mathematical models, such as material balance equations, energy