Performance Analysis Of Energy Recovery From The Reduction Of Natural Gas Pressure

In the process of reducing the pressure of natural gas through the throttle valve,the temperature of natural gas will be too low due to the Joule Thomson effect of natural gas,so it is necessary to use a heating device to raise the temperature,which not only wastes the pressure energy,but also causes energy consumption.Therefore,in natural gas pressure reduction stations or user terminals that require pressure adjustment,an expander can be used to replace the throttle valve,and the pressure energy during the pressure reduction process of natural gas can be converted into mechanical energy for power generation and supply to users who need electricity.If the existing pressure reduction process is improved,not only a large amount of potential energy can be effectively recovered,but also actual economic benefits can be produced.This article aims to analyze the benefits of two typical pressure energy application scenarios of natural gas pipelines——the TT storage and distribution station in A city and the CS data center energy station in B city,so as to guide the improvement and optimization of actual projects.The main research content and research methods are as follows:(1)Using Aspen PLUS to carry out system modeling for typical natural gas pipeline pressure energy application scenarios.In the the TT station,the pure natural gas pipeline pressure energy system(NGPE),the natural gas pipeline pressure energy system combined Organic Rankine Cycle(NGPE/ORC)and the natural gas pressure energy system combined Kalina cycle(NGPE/KC)are proposed.Meanwhile,in the CS data center energy station,natural gas pipeline pressure energy system combined the distributed energy system and carbon dioxide capture system(NGPE/DES/CCS)and the natural gas pipeline pressure energy system combined the distributed energy system(NGPE/DES)are proposed.In the Aspen PLUS software,the pressure energy of the natural gas pipeline is modeled and simulated based on the survey results,and the sensitivity of the relevant parameters affecting the pressure energy of the natural gas pipeline is analyzed.(2)According to the five natural gas pipeline pressure energy utilization processes proposed in this paper,a corresponding benefit evaluation model is proposed.The benefit evaluation model includes energy and exergy analysis,environmental analysis and economic analysis.The "fuel-product" analysis method is used to analyze the exergy and economy,and the Sima Pro software is used to evaluate the environmental effects on the system from production to operation.The specific conclusions obtained in this paper are as follows:(1)In the pressure energy recovery of the natural gas pipeline in TT station,the NGPE system has the highest exergy efficiency and thermal efficiency,while its power generation and cooling costs are the lowest,and it has relatively the smallest impact on the environment.The three pressure energy utilization systems all change significantly with the seasons.The exergy efficiency of NGPE/ORC system and NGPE/KC system fluctuate with the change of seasons,and reach the maximum in July,while the exergy efficiency of NGPE system has a trough in May and September.(2)Although the cooling capacity and power generation in the NGPE/DES/CCS system are smaller than those of the NGPE/DES system,it still meets the needs of the distributed energy supply system,and 1858kg/h of liquid carbon dioxide with a purity of 99.9% can be captured in the system.The exergy efficiency of the NGPE/DES/CCS system is higher than that of the NGPE/DES system.The overall environmental benefit of the NGPE/DES/CCS system is significantly better than that of the NGPE/DES system.