论文总字数：24339字

摘 要

焦炭是很多行业的主要原料。在炼焦过程中，大量的热量是通过烟道废气直接排往大气，不仅浪费了能源，还污染了环境。目前，对于这些大量的余热余能，其回收利用率相当低，因而存在着巨大的回收潜力。本设计“8万Nm³/h焦炉竖烟道烟气余热锅炉设计”正是基于这样的现实背景，设计一台余热锅炉以回收焦炉排放烟气的余热，生产出0.8MPa(g)的蒸汽以作生产工艺之用，达到节能减排和提高能源利用率的目的。

焦炉烟道废气余热回收利用需解决以下问题，焦炉烟道废气成分复杂，含硫量较高，由于省煤器在烟气出口处管壁温度常常低于露点，容易产生低温气体露点腐蚀。另外，在余热回收时如果烟气侧阻力过大可能会影响焦炉生产、破坏焦炉的压力操作。烟气中灰分较多，容易在管壁上形成积灰，从而影响传热效果。汽包相对于锅炉的位置选取要合理，以免出现循环停滞和循环倒流的问题。

在设计计算过程中，首先根据热平衡方程、烟气和水的进、出口温度、压力、流量等原始参数，计算出传热量；然后通过选择翅片管和径向热管规格及其结构参数，计算出总传热系数，最后确定翅片管和径向热管的数量及其排布方式。在烟气温度低于或接近露点腐蚀温度的省煤器上采用径向热管作为换热单元，在烟气温度高于露点腐蚀温度的蒸发器区域采用翅片管。这样设计能够在提高换热系数的同时解决金属结构的低温腐蚀问题。合理选择烟气工况流速，对传热管进行合理排布，使烟气侧的阻力降达到要求，不影响焦炉生产、破坏焦炉的压力操作。在合理选择烟气工况的同时对翅片间距进行合理选取，保证烟气的自清灰能力。余热锅炉采用自然循环，以传热量最大的首组翅片管束作为传热量的依据，在计算过程中选取合适的循环倍率和循环回路高度，计算出回路的流动阻力和运动压头，保证锅炉自然循环回路运行正常。

本课题的设计主要参照《废热锅炉设计》、压力容器设计手册和换热器设计手册。在烟气的流动压力降以及水动力循环等各项指标满足设计的前提下，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，设计出了本余热锅炉的施工总图、汽包和换热器主体图以及主要的零部件图。同时对汽包、传热管等材料进行强度校核，验证其是否满足工作环境强度要求。本次设计结果满足任务书的设计要求，在安全性和经济性及环保要求方面均合格。

关键词： 余热锅炉 热管省煤器 自然循环 焦炉烟气

The design of 80000 Nm³/h coke oven flue gas waste heat boiler with vertical flue gas path

Abstract

Coke is the main raw material in many industries. In the coking process, a large amount of heat through the flue gas is directly discharged to the atmosphere. This is not only waste energy, but also environment pollution. Currently, for this large number of waste heat and energy, its recycling rate is quite low, so there is a huge recovery potential. This design of 80000Nm³/h coke oven flue gas waste heat boiler with vertical flue gas path is based on the realistic background to produce steam with 0.8MPa (g) pressure for the production, and to achieve the purpose of energy conservation, reduce emission and improve the energy utilization.

Following problems must be solved in the use of coke oven flue gas waste heat recovery. The coke oven flue gas was complex and with higher sulfur content. The economizer in outlet of flue gas path is with the low tube wall temperature always and below the dew point of the flue gas. So it should be paid much more attention on the low-temperature dew point corrosion problems. In addition, if the resistance of flue gas was too large, the coke oven production and operation were destructed when the waste heat recovering. There was much ash in the flue gas. So it could form ash accumulation on the heat transfer surface of the tube wall and affect the heat transfer effect if it was treated not unsuitably. The position of the drum relative to the boiler should be reasonable to avoid the problem of the stagnation and flow backward for circular circulation

In the process of design, the first was that heat transfer was calculated which based on the heat balance equation, the inlet and outlet temperature, pressure, flow and other original parameters of the flue gas and water. Then, the total heat transfer coefficient was calculated by choosing fin tube and heat pipe specifications and its structure parameters. Finally, the number and arrangement of fin tubes and heat pipes are determined. Thermal pipe as heat exchange unit was adopted for economizer in the flue gas temperature below or close to the dew point corrosion temperature; fin tube was adopted for evaporator region in the flue gas temperature higher than the dew point corrosion temperature. The heat transfer coefficient could be improved while the problem for the low temperature corrosion of metal structures could be solved under the design. Flow rate condition of gas and heat transfer tubes has been arranged for reasonable, the gas side pressure drop have been to meet the requirements, not affection the production of coke oven and destruction of coke oven operation pressure. The fin distance have been chosen reasonably while reasonably chosen the flue gas operating condition so as to ensure the dust removing ability of the flue gas. Natural circulation was adopted for waste heat boiler, the heat of the first group of finned tube bundle as a basis for heat transfer, chosen proper circulation ratio and loop height in the calculation, the flow resistance and pressure head of circuit was calculate to ensure boiler natural circulation loop operating normally.

In this thesis, "waste heat boiler design", pressure vessel design manual and heat exchanger design manual was referenced. Under the premise of the indicators in the flue gas flow pressure drop and hydrodynamic circulation which was satisfied for the design, considered various factors, chosen the applicable and reasonable form of economic structure for structural design, and the same time meeting the manufacture, repair, assembly, transportation and maintenance requirements, a general view of the waste heat boiler construction, the drum and the heat exchanger and the main body parts diagram in Fig has been designed. While the intensity of the drum, heat transfer tube and other materials has been checked, and whether it could satisfy the working environment strength requirements. The design results meet the requirements of the mission statement, and its safety, environmental protection and environmental requirements were qualified.

Key words: Heat Pipe Economizer, Natural Cycle, Waste Heat Boiler, Coke Oven Flue Gas

目 录

摘 要 I

Abstract III

第一章 绪论 1

1.1 我国工业余热资源及其利用现状 1

1.2 焦炉烟气余热回收 3

1.2.1 焦炉烟气 3

1.2.2 烟气余热回收中的换热器 3

1.2.3 焦炉烟道烟气余热回收装置的工艺布置 4

1.3 余热回收中的换热原理 5

1.3.1 普通传热管的换热效率 5

1.3.2 热管换热效率 6

1.4 热管的基本特性及应用 8

1.4.1 热管的基本特性 8

1.4.2 热管的应用 8

1.5 课题的必要性和意义 9

第二章 8万N/h焦炉竖烟道烟气余热锅炉的设计 10

2.1 设计要求 10

2.2 余热锅炉设计中要考虑的问题 10

第三章 热力计算及结构设计 11

3.1 原始参数 11

3.2 烟气侧定性温度及参数 12

3.3 蒸发器设计 14

3.3.1 翅片管参数 14

3.3.2 确定迎风面积及迎风面管排数 15

3.3.3 求总传热系数 15

3.3.4 所需翅片管数及排列 17

3.3.5 通过蒸发器的压力降 17

3.4 离散型算法计算第一排翅片管 18

3.5 省煤器设计 19

3.5.1 热管参数 21

3.5.2 确定迎风面积及迎风面管排数 21

3.5.3 求总传热系数 22

3.5.4 所需热管管数及排列 24

3.5.5 通过省煤器的压力降 25

3.6 余热锅炉的结构设计 26

3.6.1 传热器本体结构设计 26

3.6.2 壳体结构设计 26

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