论文总字数：29748字

摘 要

传统机械压汽蒸馏技术，采用金属制蒸发冷凝器和预热器。考虑到装置的作用对象是具有一定无机盐含量的地下水，对金属有一定的腐蚀性，因此具有良好耐腐蚀性能的玻璃制预热器在本文被提出。对于使用玻璃制换热器取代传统的金属制预热器的优势，还体现在性能上：由于采用真空玻璃管作为换热器的壳，换热器的保温性能更佳；以及透明且耐高温的高硼硅玻璃，能为后期将太阳能引入到预热器内给系统补充能量的方案提供可能性。从经济角度分析：金属的密度大，单位重量价格高，单位换热面积的价格也高。近期直通式全玻璃耐高温真空管刚被研制成功，价格相对金属材料更为低廉，使得本预热器采用玻璃管壳式换热器具备了可行性。因此，机械压汽蒸馏系统中的金属换热器可以被玻璃制换热器所取代。

本文主要对采用玻璃管壳式预热器替代传统的板式换热器的可行性进行了讨论并给出了设计方案。已有的机械压汽蒸馏系统中预热器采用的是逆流式板式换热器，能将冷流体的温度升高至与热流体最高温度温差不超过5 的水平。而本文中，是根据现有的玻璃管材料的特殊尺寸进行设计，采用的是顺流式管壳式换热器。首先对于给定规格的材料设计出给定排布形式的预热器，并对其进行热力预算，比较其在特定工况下的换热系数与传统的金属制管壳式换热器换热系数，然后在不同的蒸发温度对其进行数值计算，给出了该预热器在稳定运行下各处温度的数值解。此外讨论了由于原水含盐量较低可以实现浓盐水零排放的处理方法，还引入太阳能作为加热能源用于辅助加热。

关键词：地下水净化；机械压汽蒸馏；管壳式预热器；玻璃；

Abstract

The traditional mechanical vapor distillation technology uses a metal evaporative condenser and preheater. Considering that the object of the device is groundwater with a certain inorganic salt content, it has certain corrosiveness to the metal, so a glass preheater with good corrosion resistance is proposed in this paper. The advantages of using a glass heat exchanger instead of a conventional metal preheater are also reflected in the performance: due to the use of a vacuum glass tube as the shell of the heat exchanger, the heat exchanger has better insulation properties; and is transparent and resistant to high temperatures. The high borosilicate glass can provide the possibility of later introducing solar energy into the preheater to recharge the system. From the economic point of view, the density of metal is high, the price per unit weight is high, and the price per unit of heat transfer area is also high. Recently, the straight-through all-glass high-temperature resistant vacuum tube has been successfully developed, and the price is relatively low compared with metal materials, making it possible to use a glass shell-and-tube heat exchanger in this preheater. Therefore, metal heat exchangers in mechanical vapor distillation systems can be replaced by glass heat exchangers.

This article mainly discusses the feasibility of replacing the traditional plate heat exchanger with a glass shell-and-tube preheater and presents the design scheme. The existing preheater in the mechanical vapor distillation system uses a counterflow plate heat exchanger, which can raise the temperature of the cold fluid to a level that does not exceed 5°C from the maximum temperature of the hot fluid. In this paper, the design is based on the special size of the existing glass tube material, and the forward flow shell-and-tube heat exchanger is used. First, a given arrangement of preheaters is designed for a given material and a thermal budget is made to compare the heat transfer coefficient of the preheater with that of a conventional metal shell-and-tube heat exchanger under specific conditions. The coefficient is then numerically calculated at different evaporation temperatures, and the numerical solution of the temperature of the preheater at various temperatures is given. In addition, the treatment method for zero discharge of concentrated brine due to the low salt content of raw water is discussed, and solar energy is also introduced as a heating energy source for auxiliary heating.

KEY WORDS: Groundwater purification; mechanical vapor compression; shell and tube preheater; glass;

目录

摘要 I

Abstract II

符号表 iii

第一章 引言 4

1.1中国苦咸水问题概述 4

1.2苦咸水淡化技术概述 5

1.2机械压汽蒸馏法的应用 6

第二章 预热器的设计 8

2.1 机械压汽蒸馏技术运行原理 8

2.2全玻璃管壳式预热器的采用方案 9

2.3预热器热力初参数的确定 10

2.4换热器部件设计 11

2.4.1换热管 11

2.4.2换热管 12

2.4.3壳体及导流结构 12

2.4.4膨胀节 12

2.4.5管箱 13

2.4.6防冲板 13

2.4.7防短路结构 13

2.4.8 防结垢 13

第三章 预热器的热力数值解 15

3.1 热力计算 15

3.2 热力分析 16

3.3 污垢热阻的考虑 20

第四章 浓盐水和太阳能的讨论 21

4.1 浓盐水的零排放 21

4.2 太阳能辅助加热 22

致谢 24

参考文献 25

符号表

第一章 引言

1.1中国苦咸水问题概述

我国淡水资源贫乏和用水情况紧张的严峻形势已是社会公认的事实。目前，国家和社会层面的解决办法主要有：1、积极争取外调淡水资源；2、节约用水；3、以及污水（包括海水，高盐分地下水）净化利用等。

外调淡水资源需要政府协调各全社会的资源来统筹兼顾，具有初投资高，工期长的缺点。随着社会的发展，水资源的持续开发使得调水的可行性，因调水距离变远，工程难度提高而降低，城市供水的成本不断地提高。调水工程由于成本过高，大都只适用于东部发达地区的城市圈，对于缺水的西部地区和中国广大农村地区则完全不适用。

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