含蜡热油管道低输量时结蜡对能耗的影响

结蜡现象对含蜡热油管道的运行能耗存在着两个方面的影响。其正面影响是管道结蜡层的存在 ,将降低管道总传热系数 ,使热力费用减少 ;负面影响是结蜡层会使管道的通流截面积减小 ,摩阻增大 ,所耗动力费用增加。特别是当管道长期处于低输量、偏离经济流速运行时 ,结蜡层的存在会对管道的热能及压能消耗产生更为显著的影响。为探讨结蜡层对管道运行经济性的影响规律 ,通过对比低输量下有无结蜡层时的管道能耗费用 ,并以节省的能耗费用最大为目标 ,建立了求解管道低输量运行时的经济结蜡厚度的数学模型。算例的计算结果表明 ,当管道输量低于设计值时 ,都对应着一个经济结蜡厚度 ,使得管道运行的能耗费用最省 ;同时在一定输量范围内 ,当输量下降的幅度越大时 ,其经济结蜡厚度亦随之增加 ,并且所节省的能耗费用亦越多。此模型为确定热油管道低输量时的经济结蜡厚度及经济清蜡方案提供了一定的理论依据

The Effect of Wax Deposition on the Energy Depleting for Waxy Hot Oil Pipelinein Low Throughput Rate

The wax deposition affects energy depleting of transportation on two aspects in waxy hot oil pipeline. The positive effect is that the total heat transfer coefficient of the pipeline will decrease, thus the heating power cost will decrease too. The negative effect is that the effective cross-sectional area of the pipeline will become smaller, then the friction loss and power cost will increase. The wax deposition obviously affects on the heat energy and kinetic energy depletion particularly when the pipeline runs at a low throughput rate in a long time. To study the effective rules of the economic transportation in pipeline, through comparing the energy depleting with wax deposition and without wax deposition a mathematical model for resolving the economic wax deposition thickness when the pipeline transporting in low flow rate was established, in which the maximum driving energy depleting was taken as object. The results show when the flow rate is lower than the designed flow rate, there is an economic wax deposition thickness with which the energy depleting is the lowest. And with the flow rate is lowing, the economic wax deposition thickness is increasing and the saved energy depleting is rising. This model provides a theoretical basis for determining the economic wax deposition thickness and making plan to clear wax when paraffin is transported in hot oil pipeline in low throughput rate.