DRB-4Z型旋流煤粉燃烧器流场及燃烧特性数值模拟  

Numerical simulation of flow field and combustion characteristics of DRB-4Z swirl pulverized coal burner

作　　者：胡耀辉 彭志敏[2] 李永华[1] HU Yaohui;PENG Zhimin;LI Yonghua(Department of Power Engineering,North China Electric Power University,Baoding071003,China;Department of Energy and Power Engineering,Tsinghua University,Beijing100084,China)

机构地区：[1]华北电力大学动力工程系,河北保定071003 [2]清华大学能源与动力工程系,北京100084

出　　处：《洁净煤技术》2022年第6期150-158,共9页Clean Coal Technology

基　　金：国家重点研发计划资助项目(2019YFB2006002);华能集团总部科技项目基础能源科技研究专项(一)资助项目(HNKJ20-H50)。

摘　　要：目前大容量的机组普遍采用对冲式锅炉,对冲式锅炉的燃烧效果取决于燃烧器性能。为了分析DRB-4Z型旋流煤粉燃烧器流动及燃烧特性,运用Fluent软件对单只燃烧器流场分布和某单机容量1000 MW超超临界机组(采用DRB-4Z型旋流煤粉燃烧器)燃烧过程进行模拟仿真。研究了一次风风速,内、外二次风风速,旋流强度对一次风刚度、回流区位置和范围的影响。对单只燃烧器流场模拟结果表明:DRB-4Z型旋流煤粉燃烧器一次风风速与回流区范围呈反比,额定负荷下一次风风速为16 m/s时流场分布较好,低负荷时一次风风速不宜低于12 m/s,避免煤粉着火点距燃烧器出口过近,高负荷下一次风风速不宜超过20 m/s,保证煤粉在燃烧初期得到充足的热量;内、外二次风风速与回流区范围成正比;内二次风风速28 m/s、旋流强度0.75时流场分布较好,对易燃煤种内二次风叶片开度可设置为30°、旋流强度为0.52,推迟一次风与内二次风的混合降低NO_(x)生成。对难燃煤种内二次风叶片开度可设置为50°、旋流强度为1.02,保证回流区卷吸到足够的高温烟气使煤粉稳定燃烧;对锅炉燃烧过程模拟结果表明:炉膛中上层燃烧器区域温度最高,最高温度可达1900 K,主燃区处于严重缺氧状态,主燃区严重缺氧虽可降低NO_(x)生成,但还原性气体CO与H_(2)S在燃烧器出口区域大量生成,易造成水冷壁高温腐蚀。At present,hedge boilers are widely used in large capacity units,and the combustion effect of hedge boilers depends on the per⁃formance of burners.In order to analyze the flow and combustion characteristics of DRB-4Z swirl pulverized coal burner,the flow field dis⁃tribution of a single burner and the combustion process of a 1000 MW ultra supercritical unit(using DRB-4Z swirl pulverized coal burn⁃er)were simulated by Fluent software.The effects of primary air speed,internal and external secondary air speed and swirl intensity on pri⁃mary air stiffness,location and range of reflux area were studied.The flow field simulation results of a single burner show that the primary air velocity of DRB-4Z swirl pulverized coal burner is inversely proportional to the range of reflux area.When the primary air velocity is 16 m/s under rated load,the flow field distribution is better.The primary air velocity under low load should not be less than 12 m/s,so as to avoid the ignition point of pulverized coal being too close to the burner outlet,and the primary air velocity under high load should not ex⁃ceed 20 m/s,so as to ensure that pulverized coal gets sufficient heat at the initial stage of combustion,the wind speed of internal and exter⁃nal secondary air is directly proportional to the range of reflux area,when the wind speed of internal secondary air is 28 m/s and the swirl intensity is 0.75,the flow field distribution is good.For combustible coal,the opening of internal secondary air blade can be set to 30°,andthe swirl intensity is 0.52,so as to delay the mixing of primary air and internal secondary air and reduce the generation of NO_(x).For difficult coal combustion,the opening of secondary air blade in the seed can be set to 50°,and the swirl intensity is 1.02 to ensure that enough high-temperature flue gas is entrained in the reflux area to make the stable combustion of pulverized coal.The simulation results of boiler combustion process show that the temperature in the middle and upper burner area of the fu

关 键 词：旋流燃烧器 旋流强度 数值模拟 流场分布 回流区 燃烧特性 

分 类 号：TE662[石油与天然气工程—油气加工工程] S216[农业科学—农业机械化工程]