Research On Optimized Operation Techniques Of West-East Gas Pipeline Project ?

With the development of long-distance natural gas pipelines,reducing energy consumption of gas transportation has become a burning question,so the optimization of natural gas pipeline operation is now under urgent attention from its operators.Due to the energy gas transportation needs mainly come from compressor stations,the energy reduction at compressor stations can make a big difference to the whole energy consumption of gas pipelines.On the premise of satisfying customer needs and guaranteeing the safety of pipeline transportation,the key point of pipeline administration and management is finding the proper way of setting compressor configuration and making optimum operational programs to reduce energy consumption.Based on the above reasons,the method to introduce optimization technique into long-distance natural gas pipelines and control pipeline operational process scientifically has become the main issue of natural gas transportation.In order to solve this problem,the existing optimized mathematical models and their features and limitations have been analyzed at two approaches(the optimization of compressor configuration and the optimization of pipeline),including algorithm,calculating examples and application effects on the basis of a large number of documents.This thesis is aimed at operational optimized problem of West-East Gas Pipeline Project I(WEPP I).According to the actual situation of main line compressor stations,optimization models of compressor station configuration and pipeline have been built,and calculation algorithm is also been discussed which is analyzed with engineering project later.The main results and conclusions obtained are as follows:(1)Domestic and foreign literature research about the latest study of compressor performance,the optimize model of compressor configuration and natural gas pipeline has been done.Some scholars have focused on the optimization of compressor configuration,but the lack of systematic pattern to generalize this optimization.There is space for further optimization of long-distance natural gas pipelines.And basic parameters and operational aspect of WEPP I have been analyzed;(2)The differences between design performance and practical performance of compressor are analyzed by multi-transform algorithms,coefficients of performance fitting formulas are calculated after conversion.Multiple nonlinear fitting is been done by MATLAB,take pressure head as example,error of fitting result is around 1%which is acceptable in engineering practice;(3)The optimization model of compressor configuration has been built.The objective function is the minimum energy consumption of compressor station;optimization variable is the flow of every single compressor;the constraints are state equation of gas,flow constraint,pressure constraint,strength constraint,compressor speed constraint.Calculation method has been determined by analyzing model features.Use PCL500-4 and PCL400 as examples to test optimization method.Results show that:compressor unit of same type can average the flow directly;but compressor unit of different type must optimize the flow distribution.The example reduce station power 837.2kW and gas consumption reduction is 0.96×104Nm3/d;(4)Known conditions including:pipeline length,diamer,wall thickness,elevation,location of compressor stations,limitations of outbound temperature and pressure,friction loss,parameters of gas source,minimal pressure at pipe endpoint,atmospheric temperature and soil temperature along the pipeline,heat transfer coeffient,hydraulic parameters and thermal parameters can be calculated..The optimization model of gas pipeline has been built.The objective function is the minimum energy consumption of the whole pipeline;optimization variable are outlet pressures of compressor stations and on-off state of each compressor;the constraints are flow constraint,pressure constraint,strength constraint,pressure drop equation,flow equilibrium equation,compressor power constraint;(5)Accroding to the model features,Dynamic Programming has been chosen to solve the model.Based on the optimization model of compressor sonfiguration and pipeline,DP model of gas pipeline has been built.And a living example has been calculated by Matlab.And the optimization results of WEPP I shows that the pressure drop reduction of prioritization scheme are 3.20MPa and 6.64 MPa respectively;the energy consumption reduction of prioritization scheme are 7515.25 tce and 10746.67 tce respectively;the production unit consumption reduction of prioritization scheme are 16.24 kgce/(107Nm3·km)and 20.63 kgce/(1O7Nm3·km);the energy dissipation ratio reduction are 0.32%and 0.43%.The rusults prove that the optimization method this thesis proposed is effective.