Study On Thermal Insulation Materials And Thickness Of Heating Pipeline In Pipe Gallery

With the rapid economic development,the process of industrialization and urbanization has accelerated,and the people's requirements for the urban environment have gradually increased,which has further promoted the construction of underground comprehensive pipe corridors.At the same time,along with the continuous upgrading of the consumption structure and the increase in energy demand,resource and environmental issues have become one of the bottlenecks restricting China's economic and social development.The energy saving and emission reduction situation is grave and the task is arduous.After entering 2014,the government vigorously promoted the development of comprehensive pipeline projects.However,the heating pipes laid in the gallery still technically remain on the basis of the laying of trenches,and there are relatively few relevant studies.In urban heating projects,pipe insulation is an important part of energy conservation.Appropriate insulation materials and appropriate insulation thickness are the key to ensure the energy-saving effect of heating pipes.However,there is no special study on the heat preservation of integrated emerging pipelines.However,there is no special study on the heat preservation of integrated emerging pipelines.The current regulations concerning the integrated pipeline corridors and the heating pipelines adopt high density polyethylene outer sheathed rigid polyurethane foam prefabricated direct buried thermal insulation tubes.However,the prefabricated insulation pipe insulation materials and insulation enclosures do not meet the requirements of the comprehensive pipe gallery fire protection specifications.1)The paper selects the traditional thermal insulation material and new thermal insulation material suitable for thermal insulation of pipeline heating pipelines.The thermal characteristics of these thermal insulation materials are analyzed.The method for calculating the thickness of the insulation layer in the relevant current specifications is combed and analyzed and compared in depth.2)The paper proposes a calculation method suitable for the insulation thickness of the integrated pipe gallery heating pipe,which is equivalent to the insulation thickness method.Compared with buried heating pipes(directly buried prefabricated insulation pipe heating pipes),the thermal insulation pipe of the prefabricated insulation pipe in the pipe gallery was destroyed in its integrity when installed,and the thermal insulation performance was affected.In order to avoid recurrence of the large amount of heat generated by conventional trenches,the thermal insulation of the heating pipes of the gallery should be improved,at least to maintain the insulation level of the direct-buried heating pipeline.The thickness of the insulation layer means: The insulation thickness of other insulation materials when the heat dissipation per unit area of the heating pipe of the pipe gallery is equal to that of the direct-buried heating pipe(high-density polyethylene outer pipe rigid polyurethane foam pre-cast buried pipe).The calculations of the insulation thickness of flame-retardant polyurethanes and aerogel blankets in the major cities in the country are provided for the reference of the heating pipelines of the pipe gallery.3)The paper conducted an economic and technical comparison of four different types of insulation materials.It was concluded that when the heating pipes of the gallery are made of new insulation materials whose thermal conductivity is not greater than that of flame-retardant rigid polyurethanes,the heat loss of the economic thickness of the insulating layer is greater than the heat loss of the thickness of the insulating layer,and the heat loss from the heating pipe of the pipe gallery reproduces the bad heat loss of the pipe trench pipe.Therefore,for the new thermal insulation material whose thermal conductivity is not greater than that of the flame-retardant rigid polyurethane,the thermal insulation layer should use a considerable thickness of the thermal insulation layer.On the contrary,the economical thickness is still suitable for the heat-insulating material whose thermal conductivity is larger than that of the flame-retardant rigid polyurethane.4)According to the prices of insulation materials provided by manufacturers,economic analysis shows that the annual cost of aerogel insulation felt as the insulation material is the highest,which is 1.9 times that of flame-retardant rigid polyurethane and 5.4 times that of glass wool.And 6.8 times of rock wool;The cost of flame-retardant rigid polyurethane is middle,and the annual cost of rock wool insulation layer is the smallest.The annual cost of glass wool insulation layer is similar to that of rock wool,which is slightly larger than the annual cost of rock wool insulation layer.