低氮燃烧模式下燃煤锅炉水冷壁沉积物与腐蚀层成分分析  

Compositional analysis of deposits and corrosive layer on water-walls inside a coal-fired boiler under low-NO_(x) combustion mode

作　　者：王毅斌[1] 王萌 谭厚章[1] 张思聪 张晓东 杨祖旺 WANG Yibin;WANG Meng;TAN Houzhang;ZHANG Sicong;ZHANG Xiaodong;YANG Zuwang(School of Energy and Power Engineering,Xi′an Jiaotong University,Xi′an 710049,China;China Energy Investment Corporation Branch Company of Yuci Power Generation,Jinzhong 030600,China;Xi′an GeRui Power Science and Technology Co.,Ltd.,Xi′an 710049,China)

机构地区：[1]西安交通大学能源与动力工程学院,陕西西安710049 [2]国家能源集团榆次发电分公司,山西晋中030600 [3]西安格瑞电力科技有限公司,陕西西安710049

出　　处：《洁净煤技术》2021年第5期204-211,共8页Clean Coal Technology

基　　金：国家自然科学基金资助项目(51876162,51906198)。

摘　　要：低氮燃烧改造后煤粉炉内最上层燃烧器同燃尽风喷口之间区域水冷壁附近的还原性气氛变强,管壁发生硫化型高温腐蚀的风险骤增。以一台330 MW四角切圆煤粉锅炉为对象,取样收集炉内多处水冷壁区域进行了灰渣与腐蚀层元素与矿物相表征,分析炉内水冷壁结焦的原因以及管壁高温腐蚀机制。结果表明,不同位置水冷壁所黏附熔渣中Si和Al元素均主要以莫来石(Al_(6)Si_(2)O_(13))和硅线石(Al_(2)SiO_(5))形式存在,提高了灰颗粒的熔融温度;而Fe元素主要以Fe_(2)O_(3)存在,其富集度显著高于碱金属或碱土金属。B层和F层燃烧器水冷壁所在高度区域黏附层状沉积物中高度富集S、Zn元素及少量Pb元素,Zn元素质量分数高达20%,主要以PbS、ZnS和ZnAl_(1.04)S_(2.13)的形式存在。F层燃烧器高度收集灰渣表面所附着的浮灰中仍含有约7%未燃尽碳,说明该区域旋转气流存在刷墙行为;灰样由Si、Al、Fe、C、S和Zn元素构成,主要以莫来石、赤铁矿、硫化物形式存在。管壁硫化氢腐蚀层以Fe_(1-x)S、Fe_(7)S_(8)、Fe_(9)S_(10)和Fe_(3)O_(4)为主,还含有少量PbS和PbO_(1.57)。腐蚀层中Fe_(1-x)S存在多种晶型结构,可能源于当地不同的H_(2)S分压和温度。黏附灰渣中的含Zn和Pb组分主要通过气化-冷凝和所黏附未燃尽碳颗粒释放析出2种方式富集,而富硅铝酸盐和富铁颗粒则主要是通过惯性撞击和热泳沉积的方式发生黏附。The reducing atmosphere at these regions between the top burner and the SOFA nozzle becomes stronger after the low-NO_(x) combustion retrofit for a coal-fired boiler.Under this condition,the risk in high-temperature corrosion on water-walls increases sharply.Taking a 330 MW Tangentially Pulverized coal boiler as the object,samples were collected from water-walls surface at different position.The ash and corrosion layer were characterized by elements and minerals,and the causes of slagging on the water-cooled wall in the furnace and the high-temperature corrosion mechanism of pipe wall were analyzed.The results show that Si and Al elements in slags adhered to the water wall at different positions mainly exist as Al_(6)Si_(2)O_(13)and Al_(2)SiO_(5),which increase the fusion temperature of ash particles.Fe element mainly exists in Fe_(2)O_(3) and its enrichment is significantly higher than alkali or alkali earth metals.S and Zn elements and a small amount of Pb element are highly enriched in the layered deposits on water-walls which are located at the central height of B and F layer of burner.The content of Zn element is as high as 20%,mainly in the form of PbS,ZnS and ZnAl_(1.04)S_(2.13).The fly ashes deposited on the surface of slags collected at the central height of F layer burner still contains about 7%unburnt carbon,which indicates that swirling flue gas may scour the water-walls.These fly ashes are mainly composed of Si,Al,Fe,C,S and Zn elements,mainly in the form of mullite,hematite and sulfides.The corrosive layer on the water-wall is mainly Fe_(1-x)S,Fe_(7)S_(8),Fe_(9)S_(10)and Fe_(3)O_(4),and contains a small amount of PbS and PbO_(1.57).The formation of Fe_(1-x)S with varied crystal structure may be attributed to the difference in the local H_(2)S partial pressure and temperature.Zn and Pb containing species are enriched in layered deposits via vaporization-condensation and the release from unburnt carbon particles adhered on depositing surfaces.While silicoaluminate-rich and iron-rich ash particles stic

关 键 词：燃煤锅炉 低氮燃烧 结渣 硫化氢 高温腐蚀 成分分析 

分 类 号：TK16[动力工程及工程热物理—热能工程]