Research On Temperature Distribution Characteristics And Improvement For Thermal Insulation Of Thermal Power Pipelines With Large Cross-sectional Area

In order to improve the efficiency of power generation and guarantee the safety, insulation is always required to be wrapped around the thermal power pipelines in power plant. Economic thickness method is the most popular method used for designing insulation of heat pipes. However, an evident deviation exists between the practical heat loss and the designed heat loss under the influence of the sink of material. In this article we investigated the horizontal circular pipelines that suffers a lot from the difference of the local heat leakage, theoretical results indicate that deformation of the insulation material under the influence of the gravity and natural convection around the pipeline are the two main reasons that lead to the nonuniform temperature distribution around the pipes among all the other possible reasons. CFD simulation and experiment are applied to test the influence of the two factors above, the results show that a 10% falling rate of deformation of the insulation material exists in the experiment, which plays an important role in the difference of 90 W/m2 in local heat flux, and along with the change of local thermal boundary layer caused by natural convection, the deformation has also brought a 12K difference in the local temperature distribution around the pipeline. To solve the problem,two solutions are suggested, of which the first is to change the local insulation thickness so that the local thermal resistance presents an uniform distribution around the pipeline after the falling of the insulation material occurs with a good performance of energy saving and difficulties in construction. The other method takes the deformation and natural convection into consideration while calculating the economic thickness of insulation, the method is easy to realize.