The Research Of The Key Technology Of Energy Measurement Of Double Gas Source Station Based On CFD

Energy measurement of natural gas can reflect its use value scientifically and reasonably and it has already taken the leading position in the international measurement of natural gas.At present,China is speeding up the transformation process of natural gas from volume measurement to energy measurement and has had the technical basis and conditions for the implementation of energy measurement.According to the basic principle of energy measurement of natural gas and existing research results,this thesis studied some key technologies of natural gas energy measurement from two aspects of volume measurement and calorific value determination for a double source distribution station in Sichuan Province to ensure its accuracy bsaed on the technological parameters and combined with the fluid analysis software.The specific studies are as follows:(1)According to the working principle of ultrasonic flowmeter,taking DANIEL 3400 type ultrasonic flowmeter as an example,the thesis used the method of line integral for channel node speed to calculate the average speed of each channel line based on CFD(Fluent)results and then get the volume flow in order to reflect the working condition of ultrasonic flowmeter.By comparing and analyzing three common turbulence models and solving algorithms,the standard κ-ε model and SIMPLE algorithm were used to solve the problem.According to the verification process of ultrasonic flowmeter of a transmission station in Sichuan Province,the geometric model was established and proceeded analogue simulation and by comparing with the experimental data,the feasibility of the CFD method was verified.Based on CFD method,the nearest installation positions of ultrasonic flowmeter in order to guarantee its accuracy were studied when elbow spoilers with different arrangement forms exist in its upstream.It was obtained that the recommended installation positions of the DANIEL 3400 type ultrasonic flowmeter in the downstream of seven different arrangement forms of elbow spoiler under three kinds of pipe diameters.(2)From the perspective of mixing condition of different component of natural gas in pipeline,based on the process parameters of a double gas source transmission station in Sichuan Province,the nearest position in pipeline when the natural gas with different components mix uniformly was explored using CFD method in order to ensure the accuracy of calorific value determination of double gas source distribution stations.Two kinds of mixed gas models,which are common in engineering,were established,namely collecting pipeline model and T tube model and it was determined that the mixing quality of collecting pipeline model is better than T tube model by analogue simulation.Aimed at the collecting pipeline model,this thesis analyzed the influence of inlet velocity,collecting pipe diameter and length on the quality of the gas mixture in the downstream straight pipe and obtained the the nearest position in pipeline when the natural gas with different components mix uniformly.(3)Based on the method of CFD,the volume measurement process and calorific value determination process were optimized respectively in order to effectively reduce the space of the two measurement uints and improve the accuracy of measurement.The optimization results have an important reference significance for the accurate implementation of natural gas energy measurement for double gas source distribution stations.