| The comparison or optimization of gas pipeline design schemes usually takes the lowest present value of total cost as the evaluation standard,but some literatures use the lowest gas transmission cost as the evaluation standard.In recent years,some people have proposed that Q/(PF)can be used as an evaluation index and considered that the design scheme with large Q/(PF)is more economical.In order to objectively and truly reflect the economics of the gas pipeline design,it is necessary to conduct an in-depth study on the rationality of the relevant evaluation criteria.In this paper,the lowest cost of gas transmission and the lowest present value of total cost are taken as the evaluation criteria.Firstly,the relationship and difference between the present value of total cost and the cost of gas transmission are qualitatively analyzed.Then,the annual designed transmission flow rate and length of the pipelines at home and abroad were investigated.Under the premise of not changing the length of the pipeline,for the different pipelines,based on the real transmission flow rate,the design scheme of the gas pipeline is optimized after changing the design transmission flow rate within a certain range.The influences of the changes of the basic parameters such as the benchmark rate of return,the depreciation period,the length of the calculation period,the pipeline laying cost,the investment parameters of the compressor station,and the energy consumption price on the preferred results are analyzed.A comparative analysis of the optimization results based on the two evaluation criteria reveals the links and differences between the two different criteria.In addition,the Q/(PF)values are calculated for the preferred results of different pipelines,and then a sensitivity analysis of Q/(PF)is made.The results show that this index cannot be used as a direct evaluation criterion for gas pipeline design schemes,but the Q/(PF)of the preferred result usually varies within a certain range. |
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