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浙江大学学报(工学版)
Journal of ZheJiang University (Engineering Science)  2021, Vol. 55 Issue (10): 1960-1967    DOI: 10.3785/j.issn.1008-973X.2021.10.018
    
Experimental study on preheating pulverized coal air flow by heat exchanger using thermal oil
Zhen-ya LAI1(),Rui MAO2,Yuan LI2,Ping-an ZHANG2,Xue-sen DU2,Hao ZHOU1,*()
1. State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China
2. Rundian Energy Science and Technology Limited Company, Zhengzhou 450052, China
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Abstract  

A novel technology of pre-heating the pulverized coal air flow before the pulverized coal entering the combustion chamber was proposed to reduce the cooling effect of the primary air on the furnace and accelerate the combustion of the pulverized coal. A shell-and-tube heat exchanger with finned plate that used heat transfer oil to preheat pulverized coal air flow was designed. A pilot scale test bench was constructed to experimentally analyze the effects of oil temperature, oil mass flow, air temperature, air speed, and coal-air mass ratio on the heat transfer characteristics of the system and the resistance characteristics of the test bench. The experimental results verified the technical feasibility of the heat exchanger using heat transfer oil to preheat the primary pulverized coal air flow. The proposed preheating technology had practical significance for environmental protection and energy saving. The experimental results showed that the heat transfer oil at 190 ℃ could preheat the pulverized coal air flow from 58. 4 ℃ to above 113 ℃ when the coal-air mass ratio was 0.15. The proposed preheating process was beneficial to improve the ignition performance of the pulverized coal air flow and promote the low-load stable combustion of the pulverized coal boiler.

Key words： utility boiler      pulverized coal      preheat      heat exchanger      ignition characteristics     
Received: 18 November 2020      Published: 27 October 2021
CLC:  TK 16  
Fund:  国家自然科学基金创新研究群体资助项目（51621005）
Corresponding Authors: Hao ZHOU     E-mail: lzywyyx2015@163.com;zhouhao@cmee.zju.edu.cn
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Zhen-ya LAI
Rui MAO
Yuan LI
Ping-an ZHANG
Xue-sen DU
Hao ZHOU
Cite this article:

Zhen-ya LAI,Rui MAO,Yuan LI,Ping-an ZHANG,Xue-sen DU,Hao ZHOU. Experimental study on preheating pulverized coal air flow by heat exchanger using thermal oil. Journal of ZheJiang University (Engineering Science), 2021, 55(10): 1960-1967.

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https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2021.10.018     OR     https://www.zjujournals.com/eng/Y2021/V55/I10/1960


导热油换热器预热煤粉气流的试验研究

提出在煤粉进入燃烧室之前对煤粉气流进行预热处理的新型工艺，减轻一次风对炉膛的冷却效应，加速煤粉燃烧. 设计采用导热油预热煤粉气流的带翅板管壳式换热器，搭建中试规模试验台，通过实验研究油温、油质量流量、风温、风速、煤风质量比对系统换热特性及试验台阻力特性的影响. 试验结果验证了该换热器采用导热油来预热一次风煤粉气流的技术可行性，提出的新型预热工艺具有环保节能的现实意义. 试验结果表明，当煤风质量比为0.15时，190 ℃的导热油可以将煤粉气流从58.4 ℃预热到113 ℃以上. 提出的预热工艺有利于改善煤粉气流的着火性能，促进煤粉锅炉的低负荷稳燃.


关键词： 电站锅炉,  煤粉,  预热,  换热器,  着火特性 
Fig.1 Schematic diagram of heat exchanger
Fig.2 Schematic diagram of pilot test system
工况 tin，air /℃ vair /(m·s?1) tin，oil /℃ qm /(t·h?1) R
1 60 22.8 190 0.6 0
2 60 22.8 190 1.4 0
3 60 22.8 190 2.2 0
4 60 22.8 165 1.4 0
5 60 22.8 215 1.4 0
6 60 22.8 270 1.4 0
7 40 13.3 190 1.4 0
8 40 18.4 190 1.4 0
9 40 23.9 190 1.4 0
10 40 22.0 190 1.4 0
11 60 22.0 190 1.4 0
12 80 22.0 190 1.4 0
13 60 22.5 190 1.4 0
14 60 22.5 190 1.4 0.15
15 60 22.5 190 1.4 0.25
Tab.1 Experimental conditions of preheating pulverized coal air flow
材料 tin /℃ ρ /(kg·m?3) cp /(J·kg?1·K?1) λ/(W·m?1·K?1)
导热油 165 769 2505 0.1107
导热油 190 751 2590 0.1078
导热油 215 735 2690 0.1049
导热油 270 691 2860 0.0985
煤粉 60 1400 1130 0.0650
20号钢 — 7850 465 48
Tab.2 Physical properties of materials
Fig.3 Internal structure and thermocouple position number of heat exchanger
Fig.4 Heat transfer homogeneity of heat exchanger
Fig.5 Effect of inlet oil temperature on axial air temperature profile
Fig.6 Effect of inlet oil temperature on heat transfer characteristics of heat exchanger
Fig.7 Effect of oil mass flow rate on axial air temperature profile
Fig.8 Effect of oil mass flow rate on heat transfer characteristics of heat exchanger
Fig.9 Effect of inlet air temperature on axial air temperature profile
Fig.10 Effect of inlet air temperature on heat transfer characteristics of heat exchanger
Fig.11 Effect of inlet air velocity on air axial temperature profile
Fig.12 Effect of inlet air velocity on heat transfer characteristics of heat exchanger
Fig.13 Effect of coal-air mass ratio on axial air temperature profile
Fig.14 Effect of coal-air mass ratio on heat transfer characteristics of heat exchanger
Fig.15 Resistance characteristics of heat exchanger
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