周向浓淡旋流燃烧器空气动力场的试验研究及数值模拟

国内图书分类号： TK224国际图书分类号： 621.18工学硕士学位论文周向浓淡旋流燃烧器空气动力场的试验研究及数值模拟硕士研究生：魏宏大导师：李争起教授申请学位：工学硕士学科、专业：热能工程所在单位：能源科学与工程学院答辩日期：2008年7月授予学位单位：哈尔滨工业大学Classified Index：TK224U.D.C.: 621.18A Dissertation for the Degree of M. Eng.EXPERIMENTAL STUDY AND NUMERICAL SIMULATION ON AERODYNAMIC FIELD OF TANGENTIAL BIAS SWIRL BURNERCandidate：Wei HongdaSupervisor：Prof. Li ZhengqiAcademic Degree Applied for：Master of Engineering Specialty：Thermal Energy Engineering Affiliation: School of Energy Science & Eng. Date of Defence：July, 2008Degree-Conferring-Institution：Harbin Institute of Technology哈尔滨工业大学工学硕士学位论文摘要哈尔滨锅炉厂引进英国MBEL公司(英巴)公司技术的周向浓淡旋流燃烧器，前后墙对冲布置。

在锅炉实际运行中出现了燃烧器附近水冷壁结渣的问题。

针对这个问题，结合周向浓淡旋流燃烧器的工作原理，从试验和数值模拟两方面分析产生这些问题的可能原因，建立冷态模化试验台，通过试验和数值模拟的研究，力求寻找可行性方案。

在对周向浓淡旋流燃烧器空气动力场试验结果中可以看出，中心回流区分布均不对称，原燃烧器模型当燃烧器中心风率为设计值时，中心回流区起始于燃烧器喷口内，在一次风与内二次风喷口延长线之间，煤粉易在燃烧器预混段内着火燃烧。

原燃烧器模型一次风与二次风混和过早，造成携带煤粉的一次风被旋转的中心风和二次风带动旋转，在经过预混段后进入炉膛，易被甩到水冷壁上，造成燃烧器喷口及周围水冷壁的结渣。

试验中射流扩展角最大为90°，乙二醇烟雾示踪试验表明各结构的外二次风扩展角差别不大，均在60°左右，不存在气流飞边的现象。

将内二次风喷口向炉内推进使得中心回流区逐渐变小，当推进至外二次风扩口后端时中心回流区最小，中心回流区减小则卷吸的高温烟气量也相应减小，有利于减少燃烧器喷口结渣。

从周向浓淡旋流燃烧器空气动力场模拟结果中可以得出，通过中心线回流区分布不对称的原因是一次风与燃烧器中心线偏离一定距离切向进入，切向速度沿圆周方向分布不对称，导致整个流场的分布不对称，从而产生了中心回流区分布不对称这一现象。

从原型燃烧器喷口处轴向、切向、径向速度分析可知，原型燃烧器喷口结渣的原因同样是一次风在旋转的中心风和内二次风的带动下旋转运动并不断向喷口四周扩散，造成一次风携带的颗粒被甩到燃烧器喷口和水冷壁上，从而造成结渣。

切向速度差别不大，原型燃烧器模拟的结构轴向速度衰减的最快，径向速度最大，最容易结渣，而将内二次风喷口向炉内推进,径向速度的绝对值最小，有利于减少结渣，但是不能根除结渣，模拟中同样发现不存在气流飞边的现象。

周向浓淡旋流燃烧器空气动力场试验和模拟结果分析，找到了燃烧器附近水冷壁结渣的部分原因，并提出了解决方案，在工程实践中具有一定的指导意义。

关键词旋流燃烧器；结渣；空气动力场；回流区；数值模拟- I -哈尔滨工业大学工学硕士学位论文AbstractThe circumferential bias swirl bunner(CBSB) imported from babcock UK by Harbin Boiler Company was applied in the opposed wall firing boiler and caused slagging nearby the burner. Cold model experiments and numerical simulation combined with analyse of the working principle of the CBSB was performed to explore the reasons of this problem and to search for feasible scheme.Results of the aerodynamic experiments indicate that the central recirculation zone asymmetrically distributes. When the rate of the central air equal to design value, the recirculation zone started in the spout of CBSB, between the elongation line of the primary air and the secondary air spout and the pulverized coal fired easily in the premixing segment. Therefore, the primary air and the secondary air mix in advance ,which prompt the primary air with pulverized coal to rotate with the swiveling central air and secondary air and reach the water-wall after the premixing segment. That’s the reason of slaging in the water-wall around the nozzle of burner. The most expansion angle is 90°in the experiment. It is indicated that the expansion angle of the outer secondary air had little difference in the five Structures, which is about 60°in the smoke tracing experiment. The slagging is not caused by flash. The central recirculation zone became smaller while the nozzle of inner secondary air was moved towards furnace. The least central recirculation zone can be got while the nozzle of inner secondary air was just behind the flaring of outer secondary air. The high temperature flue gas entrained by the central recirculation zone reduces with the decrease of area of the central recirculation zone which helps to reduce slagging.Results of numerical simulation of the aerodynamic field indicate that the reason of central recirculation zone unsymmetrical distribution is that the primary air is injected to the internal barrel in a tangential direction through the nozzle, and it had a certain distance deviation from the central line of the burner. Along the circumferential direction the tangential velocity distributed unsymmetrically causing the whole aerodynamic unsymmetrical distribution.According to the figures of the axial velocity, radial velocity, tangential- II -哈尔滨工业大学工学硕士学位论文velocity at the nozzle of the CBSB, the conculsion can be drawn that the reason of slagging was also the primary air with pulverized coal driven to rotate with the swiveling central air and secondary air and the pulverized coal continuously diffusing widely near the water-wall. Tangential velocity had little difference. In the Structure 1, the axial velocity was the most fast attenuation, the radial velocity was the highest, it is the easiest slagging. While the nozzle of inner secondary air was moved towards furnace, the absolute value of radial velocity reduces, which is benefital to lessen slagging, but the movement of nozzle of inner secondary air can not eradicate slagging. It was also found that the jet was not flash in the simulation.This paper studys the results of slagging through the expriments and numerical simulation of the aerodynamic field ,and puts forward solution of slagging, which has important guiding significance and application value in engineering practice.Keywords Swirl burner; Slagging;Aerodynamic field;Recirculation zone; Numerical simulation- III -哈尔滨工业大学工学硕士学位论文目录摘要 (I)Abstract (II)第1章绪论 (1)1.1 课题背景 (1)1.2 煤粉燃烧技术的研究意义 (2)1.2.1 我国的煤粉燃烧技术发展 (2)1.2.2 煤粉燃烧产生的环境问题 (4)1.2.3 煤粉燃烧产生的结渣问题 (4)1.3 旋流煤粉燃烧器的类型 (6)1.3.1 普通型旋流燃烧器 (6)1.3.2 分级型旋流燃烧器 (7)1.3.3 浓缩型旋流燃烧器 (8)1.4 课题来源及研究内容 (11)1.5 本章小结 (11)第2章 1956t/h电站锅炉概况及燃烧器工作特性 (12)2.1 1956t/h电站锅炉概况 (12)2.2 周向浓淡旋流燃烧器的结构及原理 (15)2.3 周向浓淡旋流燃烧器出现的问题 (16)2.4 本章小结 (16)第3章实验室燃烧器模型及实验系统 (17)3.1 实验系统及实验原理 (17)3.1.1 实验系统 (17)3.1.2 笛形管测量原理及其标定 (18)3.2 燃烧器模化原理 (20)3.2.1 模化原理的必要性 (20)3.2.2 几何模化 (20)3.2.3 自模化区 (21)3.2.4 动量模化 (21)3.2.5 实验模型参数的计算 (23)3.3 实验工况排定 (27)- IV -哈尔滨工业大学工学硕士学位论文3.4 本章小结 (28)第4章周向浓淡旋流燃烧器的空气动力场试验 (29)4.1 周向浓淡旋流燃烧器飘带试验分析 (29)4.2 周向浓淡旋流燃烧器烟雾示踪试验分析 (32)4.3 本章小结 (37)第5章周向浓淡旋流燃烧器空气动力场的数值模拟 (38)5.1 FLUENT软件介绍 (38)5.1.1 FLUENT软件的结构及计算流程 (38)5.1.2 FLUENT软件的求解器和边界条件 (39)5.1.3 FLUENT软件的模型 (39)5.1.4 FLUENT软件的特点 (40)5.2 FLUENT软件应用情况 (40)5.3 气相湍流模型 (41)5.3.1 微观模拟 (41)5.3.2 概率密度函数模拟 (42)5.3.3 统观模拟 (42)5.4 本文所采用的模型和条件 (42)5.4.1 本文所采用的模型 (42)5.4.2 边界条件 (45)5.4.3 工况排定 (46)5.5 周向浓淡旋流燃烧器空气动力场数值模拟分析 (47)5.5.1 周向浓淡旋流燃烧器空气动力场数值模拟与试验对比 (47)5.5.2 周向浓淡旋流燃烧器速度场分析 (49)5.6 本章小结 (53)结论 (54)参考文献 (55)攻读学位期间发表的学术论文 (60)哈尔滨工业大学硕士学位论文原创性声明 (61)哈尔滨工业大学硕士学位论文使用授权书 (62)哈尔滨工业大学硕士学位涉密论文管理 (63)致谢 (64)- V -哈尔滨工业大学工学硕士学位论文第1章绪论1.1课题背景中国是煤炭生产和消费大国，目前煤炭提供了我国一次能源的70%左右[1]，在可预见的几十年内煤炭仍是我国主要的一次能源。