474 / 2018-12-31 12:29:41

Experimental research on thermal deviation of high temperature reheater in the single tangential Π type boiler based on radiation spectroscopy analysis(基于辐射光谱分析的单切圆Π型锅炉高温再热器热偏差试验研究)

single tangential Π type boiler; high temperature reheater; radiation spectroscopy; thermal deviation; experimental measurement(单切圆Π型锅炉；高温再热器；辐射光谱；热偏差；试验测量)

全体主题 > 锅炉

A 660MW ultra super-critical Π type boiler was employed SHENHUA bituminous coal and equipped the single corner-tangential combustion system with five floors separated over fire air (SOFA) nozzles. The nozzles of SOFA can be adjusted horizontally to decrease thermal deviation. In addition, the steam pipes between the low and high temperature reheaters are cross-connected. But the superimposed phenomenon of thermal deviation of low and high temperature reheaters was found under the high load condition, the discharge temperature deviation between the two sides of steam were more than 15℃ in high temperature reheater. In order to reveal the thermal deviation of high temperature reheater in this boiler, a probe was designed and developed to measure the visible radiation spectrums of coal dust in the high temperature reheater zone by using the servo mechanism of soot blower. The particle concentration and temperature of coal dust were obtained by the parameter fitting method based on Planck’s radiation law. The measurements results show that the burning delay of pulverized coal caused by originally equipped one-level air staged combustion system and enrichment of coal dust under the action of inertia are the main reasons of thermal deviation of high temperature reheater. And the momentum of SOFA to eliminate the rotation is insufficient in this boiler. In order to improve the thermal balance of both sides, a new type of the two-level air staged combustion system was proposed as principle of retrofit scheme. There were six floors SOFA nozzles and upper SOFA nozzles were wall-tangential arrangement.
某燃用神华煤的660MW超超临界Π型锅炉，采用四角切圆、分级送风低氮燃烧方式，为降低热偏差，5层SOFA喷口均可水平摆动，且高、低温再热器之间蒸汽左右交叉设计。在高负荷工况，高、低温再热器出现偏差叠加现象，两侧出口汽温偏差达到15℃以上。为了揭示这一规律，研发了一套测量高温再热器区域可见光辐射光谱的测量探针，利用吹灰伺服机构，采集了高温再热器区域可见光谱，分析得到飞灰辐射强度，并基于普朗克辐射定律利用参数拟合法得到颗粒浓度和温度。结果表明，煤粉颗粒由于原设计的分级送风燃烧系统所导致的燃尽延迟和颗粒在惯性作用下的单侧富集所产生的辐射换热偏差是高温再热器热偏差的主要成因，同时还存在着现有SOFA消旋动量不足问题。为此，提出了将现有一段5层SOFA喷口改为两段6层SOFA喷口、并将上层SOFA喷口以墙式切圆布置的新型燃烧系统改造原则。