循环流化床锅炉屏式受热面变形原因分析及治理策略

Deformation Analysis and Treatment Strategy of Platen Heating Surface of CFB Boiler

为了掌握循环流化床(CFB)锅炉屏式受热面变形原因和治理因其导致的受热面爆管泄漏等问题,在探讨分析设备结构特征、工质流动特性、传热效果影响等基础上,结合国内现役CFB锅炉存在的屏式受热面变形问题,得到了工质流量不均匀、工质流量与热负荷不匹配、传热效果差异等是导致屏式受热面产生较大热偏差的主要原因,由此进一步诱发屏式受热面出现应力偏差造成了管屏变形现象,而屏式受热面竖直方向膨胀受阻也会导致不可逆的管屏变形。提出了屏式受热面“割管+分屏+扩径”管屏改造措施以减小管屏热偏差,“双吊架+密封改进”膨胀改造措施以实现管屏自由膨胀;从运行管理角度提出了CFB锅炉启动阶段运行控制技术措施,以减小该阶段屏式受热面的壁温偏差和热应力等。治理措施已取得良好实践改造效果,能有效解决屏式受热面的变形严重问题,具有普遍推广性。

In order to grasp the cause of the deformation of the platen heating surface of the CFB boiler and solve the problem of leakage of the heating surface caused by the deformation, the structural characteristics of the equipment, the flow characteristics of the working fluid and the effect of heat transfer are discussed and analysed. Combined with the deformation of the screen heating surface existing in the domestic CFB boiler, it is found that the uneven working medium flow, the mismatch between working medium flow and heat load, and the difference of heat transfer effect are the main reasons for the large thermal deviation of the platen heating surface, which further induces the stress deviation of the platen heating surface, resulting in the deformation of the tube platen, and the blocked vertical expansion of the platen heating surface will also lead to the irreversible deformation of the tube platen.This paper puts forward the transformation measures of “pipe cutting + split screen + diameter expansion” of the platen heating surface to reduce the thermal deviation of the small platen, and the expansion transformation measures of “double hanger + seal improvement” to realize the free expansion of the platen, and puts forward the operation control technical measures in the start-up stage of CFB boiler from the perspective of operation management, so as to reduce the wall temperature deviation and thermal stress of the platen heating surface at this stage. The deformation treatment measures of the CFB type boiler’s platen heating surface have achieved good practice and transformation effect, which can effectively solve the serious deformation problem of the screen heating surface, and is universally popularized.