保温体表面温度差异的分析

Analysis of the Difference of Surface Temperature of Thermal Insulation

某电厂2×125 MW机组保温热态验收过程中,发现一根直径相同的管道,在主保温层厚度相同的情况下,保护层采用铝板的表面温度要高于保护层为抹面层表面温度5~7℃,如何降低保护层外表面温度成为验证保温效果好坏的标准。针对该现象,对铝板和抹面层的表面温度和散热损失的关系进行了分析,发现因2种材料热辐射黑度不同,表面传热系数存在较大的差异。表面温度高的铝板保护层散热损失小,表面温度低的抹面保护层散热损失大。通过对《火力发电厂保温油漆设计规程》金属护壳和抹面材料的表面传热系数进行符合性研究,及现场实测对比,证实保温体表面温度跟保护层的散热损失和散热系数有着密切关系,所以,相同的保温厚度,要想降低表面温度,仅需改变保护层的材质即可实现。

During the thermal acceptance of a 2×125 MW unit of a power plant,a pipe with the same diameter was found.Under the same thickness of the main insulation layer,the surface temperature of the aluminum plate used in the protective layer was higher than that of the coating layer.The surface temperature of the layer is 5 to 7℃.How to reduce the temperature of the outer surface of the protective layer has become the standard to verify the good or bad insulation effect.In view of this phenomenon,the relationship between the surface temperature of the aluminum plate and the coating layer and the loss of heat dissipation is analyzed,and it is found that the thermal radiation blackness of the two materials is different.The surface heat transfer coefficient is quite different.High surface temperature aluminum protective layer heat loss is small,low surface temperature coating heat loss is large.The surface heat transfer coefficient of metal shell and matte material in thermal power plant is studied in accordance with the design rules of thermal insulation paint,and the field measurements are compared to confirm that the surface temperature of thermal insulation body is closely related to the heat dissipation loss and heat dissipation coefficient of the protective layer.Therefore,the same thermal insulation thickness,to reduce the surface temperature,then,only need to change the material of the protective layer can be achieved.