洁净煤技术

2019, (05) 106-111

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循环流化床锅炉翼形墙过热器/再热器变形分析
Deformation analysis of wing wall superheater/reheaterin a circulating fluidized bed boiler

黄智;郭学茂;李军;张缦;
HUANG Zhi,GUO Xuemao,LI Jun,ZHANG Man

摘要(Abstract):

翼形墙过热器/再热器是循环流化床锅炉的重要部件之一,位于炉膛上部,通常前墙引入、炉顶穿出,其温度与水冷壁不同,导致热态运行的膨胀量不同。翼形墙受热面进出口与水冷壁连接密封,因此膨胀系统设计具有重要意义,设计不当会导致翼形墙受热面弯曲变形,影响安全性,膨胀设计中膨胀量的计算是关键。笔者建立了循环流化床炉膛中翼形墙受热面壁温的计算模型,计算了不同负荷下稳态最高壁温,发现最高壁温没有出现在满负荷下,而是在60%左右负荷下。但实践表明,据此设计,仍存在翼形墙受热面弯曲变形,表明稳态最高壁温不是翼形墙受热面壁温最高工况。笔者研究了最大膨胀量的发生工况,提出翼形墙过热器/再热器的最大膨胀量发生在极热态启动过程中,因此建议循环流化床锅炉翼形墙过热器/再热器的膨胀量应按极热态启动工况予以计算,建议该工况的计算条件为:压力为20%额定压力,温度为计算压力下的饱和温度,蒸汽流量为锅炉最大连续蒸发量的15%。据此进行膨胀设计的循环流化床锅炉应用实践表明,采用极热态启动的壁温计算膨胀量进行膨胀系统的设计,可解决循环流化床锅炉翼形墙过热器/再热器变形问题。
The wing wall superheater /reheater located in the upper furnace is one of the important components of the circulating fluidized bed (CFB) boiler,which generally enters the furnace from the front wall and exits from the furnace roof. The tube metal temperature of the wing wall is different from that of the water wall,which results in the different expansion in thermal operation. The inlet and outlet of wing wall are sealed and connected with the water wall and therefore,the design of the expansion system is of great significance. The improper design may lead to the deformation of the heating surface of the wing wall due to their expanding difference,which results in lower safety. The expansion calculation is the key process in the design of the expansion system. In this study,the model of the tube wall temperature of the wing wall in the CFB boiler was suggested and the maximum tube wall temperatures under different loads were calculated. It is found that under 60% rather than 100% of the rated load,the tube wall temperature reached the maximum. However,the engineering practice shows that if the wing wall is designed according to this results,the wing wall deformation of the heating surface still happens in the tubes,which indicates that the maximum tube wall temperature predicted in steady state is not the highest working condition of the heating surface of the wing wall. Then the load of the maximum expansion was analyzed. Consequently,it was proposed that the maximum expansion of the wing wall superheater /reheater happened in the extreme hot start-up. Therefore,it was suggested that the maximum expansion of the wing wall superheater /reheater should be calculated under the working condition of the extreme hot start-up. A specific working condition is recommended:the 20% of the rated pressure,the saturation temperature under calculation pressure and the 15% of the steam flow rate under the boiler maximum continuous rating (BMCR). The practice of the CFB boiler,of which the expansion is designed according to the above,shows that the design of expansion system by calculating wall temperature of extreme hot start-up can solve the problem of the deformation of the wing wall superheater /reheater in the CFB boiler.

关键词(KeyWords): 循环流化床锅炉;翼形墙;过热器/再热器变形;最大膨胀量;极热态启动
circulating fluidized bed boiler;wing wall;superheater/reheater deformation;maximum expansion;extreme hot start-up

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作者(Author): 黄智;郭学茂;李军;张缦;
HUANG Zhi,GUO Xuemao,LI Jun,ZHANG Man

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