论文总字数：22681字

摘 要

我国是煤炭生产大国，近几年来，随着国家环保和节能要求的提高，小型土法炼焦已逐渐被大型机械化焦炉和热回收焦炉所代替。综合利用能源、降低生产能耗、提高企业经济效益已成为焦化行业不断发展追求的目标。因此，利用焦炉排出的高温烟气生产饱和蒸汽和过热蒸汽的余热锅炉技术为该行业实现能源综合利用、降低生产能耗提供了有效的途径。设计一台余热锅炉以回收焦炉排放烟气的余热，生产出0.7MPa(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通常会遇到以下问题，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 100000 Nm³/h the coke oven flue gas waste heat boiler with vertical flue path

Abstract

Our country is the largest producer of coal. In recent years, small indigenous coking has gradually been replaced by large-scale mechanized coke oven and heat recovery coke oven with the improvement of national environmental protection and energy conservation requirements. Comprehensive utilization of energy, reducing energy consumption and improving economic benefit of enterprises have become the target of the continuous development of coking industry. Therefore, the coke oven exhausting high temperature flue gas can be used produce saturated steam or superheated steam with the waste heat boiler technology for the industry to realize comprehensive utilization of energy, and provides an effective way to reduce the energy consumption of production. In this thesis, a waste heat boiler to recover the waste heat of coke oven flue gas,was designed to produce 0.7MPa (g) steam for the production process, to achieve energy-saving emission reduction and improve the energy utilization rate of the purpose.

Following problems must be solved in the use of coke oven flue gas waste heat recovery. The coke oven flue gas composition was complex, higher sulfur content; the tube wall temperature of the economizer at the outlet of the flue gas flow path was often below the dew point and easy to be corrupted. If the flue gas flow resistance was too large, the coke oven production and operation was destructed under the condition of waste heat recovery. There was more ash in the flue gas and could form ash accumulation on the wall surface to affect the heat transfer effect, if the flue gas velocity was not suitable. 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 and calculation, at first the heat transfer balance was calculated out 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 were determined. The heat pipe as heat exchange element was adopted in the economizer 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 conditions. Flow rate condition of gas and heat transfer tubes has been arranged reasonably, the pressure drop of the flue gas should be met the requirements, and not affected the production of coke oven operation. The fin gap distance should be chosen reasonably to ensure the dusty flue gas. Natural circulation was adopted for the waste heat boiler. The heat transfer rate of the first group of finned tube bundle was the calculation basis to choose proper circulation ratio and loop height. The flow resistance of the water-steam circuit was calculated to meet the boiler natural circulation loop operating normally.

In this thesis, “waste heat boiler design”, “pressure vessel design manual” and “heat exchanger design manual” were referenced. Under the premises 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 drawing have been designed. The intensity of the drum, heat transfer tube and other materials has been checked. 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 焦炉烟气余热分析 1

1.1.1 焦化厂节能现状 1

1.1.2 焦炉烟道气的组成 2

1.2 焦炉烟道废气的换热工艺 2

1.2.1 现有烟道废气换热工艺 2

1.2.2 烟道废气换热新工艺 3

1.3 余热锅炉分类及主要部件 3

1.3.1余热锅炉的结构形式 3

1.3.2余热锅炉的蒸发器 4

1.3.3余热锅炉的省煤器 4

1.4 焦炉烟道余热锅炉工艺系统 5

1.4.1余热锅炉工艺流程图 5

1.4.2 余热锅炉的设计可行性 5

1.4.3翅片管水管锅炉与热管换热器相结合的换热新工艺 5

1.5 小结 6

第二章 10万Nm³/h焦炉水平烟道烟气余热锅炉的设计 7

第三章 热力计算及结构设计 8

3.1 原始参数 8

3.2 烟气侧定性温度及参数 9

3.3 蒸发器设计 11

3.3.1 翅片管参数 11

3.3.2 确定迎风面积及迎风面管排数B 12

3.3.3 求总传热系数U_H 12

3.3.4 所需翅片管数及排列 14

3.3.5 通过蒸发器的压力降 14

3.4 离散型算法计算第一排翅片管 15

3.5 省煤器设计 16

3.5.1热管参数 18

3.5.2确定迎风面积及迎风面管排数B 18

3.5.3求总传热系数U_H 19

3.5.4所需翅片管数及排列 21

3.5.5通过蒸发器的压力降 22

3.6 余热锅炉的结构设计 23

3.6.1 传热器本体结构设计 23

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