论文总字数：17803字

摘 要

本设计的课题是4T/h导热油蒸发器的设计，用换热器将导热油的余热间接加热给水，产生满足生产工艺需求的热水和蒸汽。本设计采用的换热器类型为U型管式换热器，由管箱、壳体及管束等主要部件构成。这类换热器的特点是管束可以自由伸缩，不会因管壳之间的温差而产生热应力，热补偿性能好；管程为双管程，流程较长，流速较高，传热性能较好；承压能力强；管束可从壳体内抽出，便于检修和清洗，且结构简单，造价便宜。并且由于导热油的洁净度比较高，弥补了U型管式换热器换热管内清洗不便的弊端。

本设计的U型管式换热器为圆筒状卧式容器，筒内有多层盘旋管，管内为放热介质导热油的流动空间，管外与筒壳之间为吸热介质水或蒸汽的流动空间。同时发生器上装有配套的安全附件及显示仪表。发生器的热源管与有机热载体系统管网连接，并配有控制和调整阀门。当需要蒸汽或热水时，只要打开发生器热源管控制阀门，高温导热油便通过蒸发器强制循环流动，向吸热介质水或蒸汽放热，从而不断产生热水或蒸汽。通过调整控制阀门、仪表，改变导热油的流量和水与水蒸汽的流量，可得到不同压力、不同温度的饱和蒸汽。

同时本设计在结构设计中考虑到为使换热管外的汽泡顺畅地流到汽包中，本设计采用以往换热器换热管不常采用的正方形排列形式，并且为防止换热管外发生膜态沸腾，换热器筒体中只设有拉杆以及支撑板，取消了折流板。由于汽水循环采用自然循环，故热力计算过程中要选取较大的循环倍率，以严格控制上升管中的含气率，防止发生蒸汽堵塞。

另外本文还扼要介绍了U型管式换热器的特点及在工业中的应用和发展前景，详细地阐述了U型管式换热器的结构以及强度设计计算。

本设计参照GB151—2012、压力容器设计手册和换热器设计手册，综合考虑各种因素，结构设计需要选择适用合理、经济的结构形式，同时满足制造、检修、装配、运输和维修等要求；而强度计算的内容包括换热器的材料，确定主要结构尺寸，满足强度、刚度和稳定性等要求，根据设计压力确定壁厚，使得换热器有足够的腐蚀裕度，从而使的设计结果达到最优化组合。本设计结果满足任务书的设计要求，安全性和经济性及环保要求均合格。

关键词：导热油 余热回收 蒸汽发生器 U型管式换热器 自然循环

The design of evaporator for recovering heat from dowtherm oil to produce 4T/h steam

Abstract

The design of evaporator recovering waste heat from heat transfer oil to produce stem is discussed in this graduation thesis. In this design, heat exchanger was used to heat water indirectly, which can produce hot water and stem. Heat exchanger type for this design is the U type tube heat exchanger, which composed of a pipe box, shell and tube bundle and other main components. This type of heat exchanger is characterized by a bundle can be freely telescopic, so the temperature difference between the shell could not result in the thermal stress. And the performance of the thermal compensation is pretty good. Compared with other heat exchanger, this exchanger has better performance of heat transfer due to its longer tubes and higher liquid velocity. Its bundle can be extracted from the shell, so it can be conveniently maintained and cleaned. Its structure is simple and its cost is pretty cheap. And because the heat transfer oil is clean, so the defects of U type tube type heat exchanger tube’s inconveniently cleaning can be work out.

The heat exchanger is a cylindrical pressure vessel in this design, which has the multilayer spiral pipe. Flow space for the heat transfer oil is in the pipe. Flow space for the heat medium water or steam is between cylinder shell and the bundle. At the same time generator is arranged with the safety attachment and display instrument. Generator is connected with the organic heat carrier system, and equipped with controlling and adjusting valve. When the steam or hot water needs, as long as the controlling valve opened, high temperature heat transfer oil will be forced to flow through the evaporator to heat medium water or steam. Through the adjustment of controlling valves, instrumentation, the thermal oil flow and water and steam flow will be changed, so the different pressure and temperature of stem can be got.

In structural design, considering to make the bubbles smoothly flow into the drum, this design uses the heat exchanger does not often use square arrangement, which can prevent the bubble blockage. Because the steam-water cycle with natural circulation, so the steam content should be strictly controlled in the rising pipe to prevent the occurrence of vapor plug in order to avoid the accident. The drum installed at the top of the heat exchanger can make the quality of steam meets the requirements of the production process.

This paper also briefly introduces the characteristics of U type tube heat exchanger and its application in industry and the prospects for development. It also elaborates the structure and the strength calculation.

This design has a reference to GB151 - 2012, pressure vessel design manual and heat exchanger design manual. It considered various factors, such as structure design, which need to select the reasonable, economical, and satisfy structure, and the strength calculation includes heat exchanger materials, determination of main structure size, strength, stiffness and stability requirements. According to the designing pressure, the thickness of the heat exchanger was determined. And the heat exchanger’s corrosion allowance is enough, so that the design achieves the optimization combination. The design results meet the requirements of the task book, and its safety , economic and environmental requirements are qualified.

Key words: Heat transfer oil; Waste heat recovery; Steam generator; U tube heat exchanger; Natural cycle

目 录

摘 要 I

Abstract III

第一章 绪论 1

1.1课题的研究背景及目的 1

1.2导热油的定义 1

1.3导热油的分类和特点 2

1.3.1导热油的分类 2

1.3.2YD导热油的特点 2

1.4导热油的应用领域 3

1.5国内外导热油的研究进展 3

1.6 导热油锅炉 4

1.6.1导热油锅炉特性及系统流程 4

1.6.2蒸汽发生器的结构原理 4

1.6.3导热油锅炉供热系统工艺流程 5

1.7导热油蒸发器的主要特点 5

1.8课题的必要性和意义 6

第二章 4T/h 导热油蒸发器的设计 7

2.1 设计要求 7

2.2 导热油蒸发器设计中要考虑的问题 7

2.3 热力计算中遇到的问题 7

第三章 热力计算及结构设计 9

3.1 原始设计参数 9

3.2 换热器热平衡计算 9

3.2.1 传热量的计算 9

3.2.2 导热油的质量流量以及对数平均温差 10

3.2.3 导热油蒸发器的总传热系数 11

3.2.4 导热油蒸发器总传热面积 12

3.3 导热油蒸发器内阻力计算 12

3.4 自然循环回路的设计 13

3.5 导热油蒸发器的结构设计 17

3.5.1 管箱的结构设计 17

3.5.2 蒸发器筒体的设计 18

3.5.3 管板的设计 19

3.5.4 拉杆的确定 21

3.5.5 设备法兰的确定 21

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