管道双层保温经济厚度存在性分析及计算

Possibility Analysis and Calculation of Economic Thickness on Two Layer Pipeline Insulation.

为了弥补单一保温材料在抗压强度、耐高温性能、稳定性和防水性等方面的缺陷,双层保温较普遍地被应用到输油和热力管道上。在稳定传热的前提下,运用数学分析方法,按最优经济条件,即保温材料投资年分摊费用与保温后管道热损失费用之和最小的原则,对管道双层保温经济厚度存在的条件展开讨论。提出了当第一层采用保温效果好但价格贵的保温材料,而第二层采用保温效果差但价格便宜的保温材料时,双层保温经济厚度存在的必要条件是第一层保温材料的导热系数与其价格的乘积应大于第二层保温材料的导热系数与其价格的乘积;反之,则是第一层保温材料的导热系数与其价格的乘积应小于第二层保温材料的导热系数与其价格的乘积。推导出双层保温经济厚度计算公式,建立了数学模型,给出了计算程序框图。为输油及热力管道双层保温的优化设计提供了方法。

Two layer insulation has been widely used in oil and thermal pipelines so as to remedy one layer's defects in compression strength, property of high temperature resistance, stability and water proof property. Based on steady thermal conducting, through mathematic analysis and according to superior economic condition, which is refered to as minimum sum of the expense of insulation material shared by each year and the expense of heat loss of an insulated pipeline, discussion is done with the following result; The necessary requirement for the existance of the economic thickness of two layer insulation is that the product of the first layer's thermal conductivity multiplied by its cost is larger than the product of the second layer's thermal conductivity multiplied by its cost when the first layer is good in insulation effect but high in cost, yet, the second layer poor in insulation effect but low in cost. Otherwise, it should be on the contrary. In the paper, the writer gives the formula for calculating the economic thickness of two layer insulation, with the mathematic model set up together with a chart of calculating procedures, which can be a kind of method provided for design optimization of two layer insulation for oil and thermal pipelines.