Thermal Insulation Performance Test And Application Evaluation Of Heating Pipe Network

Steam heating pipe network is a heating system composed of heat source,transmission and distribution pipe network and heat users.The efficient,safe and economic operation of the pipe network is an important topic of high concern for heating engineering.In this paper,taking the long-distance steam pipeline insulation as the research object,the field steam insulation pipeline test,the temperature distribution test and numerical simulation calculation of different insulation structures,the thermal insulation,aging,compression,bending and high temperature resistance test of different insulation materials and protective layers,and the test and analysis of heat loss and heat transfer resistance of directly buried steam pipeline are carried out,and the research conclusions are as follows:1.In the field project,the thermal insulation layer of the steam pipeline in the straight pipe section,elbow and special-shaped parts is uneven in thickness,overlap and leakage,the temperature field on the surface of the steam pipeline is uneven,and there are many hot spots on the surface of the thermal insulation layer.Therefore,the standardized construction and maintenance of the thermal insulation and protective layer should be paid great attention to.2.The alumina magnesia material used for the field direct pouring repair of the thermal insulation layer has good environmental protection performance.It can replace the alumina silicate needle blanket and add a proper amount of alumina silicate fiber.The bending resistance and compression resistance of the alumina magnesia test block are obviously improved,but the strength of the test block after drying is small and fragile.It can be used for a long time under 350 ?,but it can not withstand 600 ?.3.UPVC outer protective layer has strong resistance to stampede,good corrosion resistance,and the overall color of outdoor placement becomes even and light for a long time."Rubber plastic + UPVC outer sheath" has low cost and good heat preservation effect.In the heat preservation project of steam pipe network,"aluminum silicate + glass wool + rubber plastic + UPVC outer sheath" structure is recommended.4.From high to low,the thermal insulation effect of thermal insulation materials is: nano nano,nano,Morgan ceramic fiber blanket,aluminum silicate fiber needleblanket.When the heat preservation effect of the pipeline is good,the heat flux density of the heat dissipation of the steam pipeline does not increase with the rise of the steam temperature,and the outer surface temperature of the outermost layer of the insulation structure can reach the national standard.5.The direct buried pipeline has the development prospect and the application value in the heating steam pipe network project.The temperature distribution of the insulation layer and the soil layer of the directly buried soil pipe is obtained,which can determine the thermal conductivity of the insulation layer material,the comprehensive equivalent thermal conductivity of the insulation layer and the heat flow density of the pipe heat dissipation.The heat transfer shape factor of directly buried pipe is related to the geometry of the pipe cylinder,and the heat transfer rate of the heat conduction of the directly buried pipe and the eccentrically insulated pipe can be calculated.6.Soil characteristic is the most important factor in the design of directly buried pipeline network.The soil thermal resistance decreases with the increase of soil thermal conductivity,increases with the increase of buried depth,and decreases with the increase of outer diameter of pipe insulation layer.The effect of pipe depth on soil thermal resistance is only 1% of soil thermal conductivity.