Simulation And Optimization Of The Natural Gas Long Distance Transmission Pipeline Network

Natural gas is one of the most clean and efficient mineral energy and it has been an important development goal in the world energy structure optimization at present.Pipeline transmission is the main way of natural gas long distance transportation and plays an important role in the national economy development.However,friction loss,control unit loss and swerve loss happens frequently during pipe transmission,which results in great energy loss.In order to reduce the energy consumption of natural gas pipeline transmission,chemical process simulation software-Aspen Plus and HYSYS was used to build rigorous simulation model of natural gas long distance transmission pipeline network.Considering the problem encountered by Aspen Plus and HYSYS in the optimization of natural gas pipeline network,this paper proposed a new method which integrated HYSYS with Isight-multidisciplinary integration software through two different ways.Therefore,the simulation and optimization model of natural gas pipeline network was built.The model was used to optimize the operation parameters of natural gas pipeline network.The main work of this paper is as follows.(1)The rigorous simulation model of natural gas pipeline network was built and the feasibility of the model was validated.BWRS thermodynamic method was used in the simulation and the influence of natural gas consumed by compressor station on pipeline network was also taken into account,Calculator and Adjust module was used to calculate and change the amount of natural gas into the compressor station.The objective function of the optimization is energy consumption of compressor stations.The manipulated variables are node flow,pressure and compressor speed.The constraint conditions are compressor performance parameters,node flow and pressure,pipe allowable pressure.As a result,the mathematical optimization model of natural gas pipeline network was built.(2)Aspen was integrated with Isight-multidisciplinary integration software through two different ways.Therefore,the simulation and optimization model of natural gas pipeline network was built based on the integration.The model was used to optimize the operation parameters of natural gas pipeline network,different algorithms and pressure calculation methods were used to get the best operation scheme,which reduced the energy consumption of network and demonstrated the feasibility of the approach proposed.The results of different integration methods were compared.(3)What the optimization results showed are as follow: The optimization schemes from different algorithms are basically same,but SQP has faster calculation speed and better result.The optimization results of HYSYS,compared with Aspen Plus,are basically same for simple pipe network but slightly different for cycle pipe network.The rate of fuel consumption for simple pipe network was 5.78 kg/s,which is reduced by 24.2 % Compared with reference.The amount of fuel gas consumption is 0.96 % of the total gas delivery,which reduces the fuel gas consumption by 36 % compared with the average level.Relative to the optimal solution which neglects the consumption of natural gas,the one in the paper makes compressor station energy consumption reduce by 2120 kW and the rate of fuel consumption by 2.2 %.The rate of fuel consumption for cycle pipe network was 7.33 kg/s,which takes 1.2 % of the total gas delivery and reduces the fuel gas consumption by 20 % compared with the average level.Relative to the optimal solution which neglects the consumption of natural gas,the optimal result makes compressor station energy consumption reduce by 1772.6 kW and the rate of fuel consumption by 4.8 %.The method proposed by this paper which integrated Aspen with Isight can also be widely used by other chemical engineering process and has an important practical value.