Study On Thickness Optimization And Economy Of Insulation Layer For Directly Buried Steam Pipeline

For rational design of directly buried steam pipeline insulation layer thickness,improve the economic benefit of thermal insulation layer,this paper puts forward a kind of based on life cycle cost theory,a new method for the optimization of directly buried steam pipeline insulation layer thickness and the economy has carried on the comparative analysis of different insulation scheme,for the thickness of the insulation layer directly buried steam pipeline design and scheme selection provides a theoretical basis and reference.The main research contents and conclusions of this paper are as follows:（1）A one-dimensional simplified model for calculating heat loss of directly buried steam pipelines was established by using the virtual heat source method,and the results of the one-dimensional simplified model were verified by using the two-dimensional numerical model.The results show that the relative error of the one-dimensional simplified model is less than 5%,and the calculation accuracy meets the requirements of this study.（2）Based on the P₁-P₂ method,the life cycle cost model of directly buried steam pipeline was established,the economic thickness optimization method of single insulation layer and composite insulation layer was proposed,and the calculation formula of economic evaluation parameters such as the economic benefit of insulation layer and the payback period of investment was deduced.（3）According to the characteristics of thermal insulation materials,three thermal insulation schemes are selected to compare and analyze the total cost,economic thickness,economic benefits and investment payback period of their life cycle.The results show that the composite insulation layer composed of Si O₂ aerogel felt and high temperature resistant glass wool exhibits the best economic performance at 250℃.At the same time,the sensitivity analysis results show that the thermal price,thermal conductivity coefficient of thermal insulation material,price of thermal insulation material and inflation rate are the key factors affecting the economic efficiency of thermal insulation layer.（4）To increase the thickness of economic rationality of the method used in the high temperature steam pipe,according to the heat preservation material properties and specification requirements,will limit the composite thermal insulation layer thickness of interface between temperature and economic method,puts forward the limit temperature insulation layer thickness of insulation layer between the interface optimization method,and comparative analysis of different thickness of insulation layer scheme of total life cycle cost,economic,economic efficiency and the payback period of investment.The results show that the composite insulation layer composed of Si O₂ aerogel felt and high temperature resistant glass wool exhibits the best economy at 350℃ medium temperature.