Measurement Of Gas-Liquid Two-Phase Flow By Long Throat Venturi Tube And Near Infrared Spectroscopy Technology

Gas-liquid two-phase is one of the most common two-phase system and it's widely found in many fields,such as daily life,military affairs,environment,and energy.The study of gas-liquid two-phase has great academic and engineering value.The research status of gas-liquid two phase flow is studied in this paper.By combining near infrared spectroscopy with differential pressure to measure flow rate,A new structure of the near infrared system located in the position of the venturi tube of long throat is proposed.By combining NIR spectroscopy with differential pressure measurement,the combination of near-infrared information and differential pressure information is more close and effective.Meanwhile,the detail design of measurement system is optimized,and the accuracy of measurement is improved.A single-phase water flow range of 0-11m~3/h was measured by using the new device,the outflow coefficient of the device was obtained by fitting,and the relative error of the single-phase water flow was within±1.47%.The experimental research of the gas-liquid two phase flow under the bubbly flow condition when water flow in the range of 8-11m~3/h and gas flow in the range of 0.12-0.6m~3/h,and under the slug flow condition when water flow in the range of 0.4-3m~3/h and the range of gas flow rate of 0.12-0.6m~3/h were studied by the new measuring device.The flow model was rationally constructed according to the characteristics of the typical flow pattern.The influence of gas-liquid two-phase interface on near-infrared measurement results was analyzed and the phase fraction measurement model was established.The flow measurement model suitable for this device is obtained by a reasonable correction of the classic flow measurement model.The new measuring device has a good measurement effect on the gas-liquid two-phase flow,and has a small measurement error.The measurement error under the bubbly flow condition of the liquid volume fraction and the gas volume fraction was within±0.52%and±10%,respectively.The relative error of total flow measurement was within±1.01%.The relative error of the volume flow measurement obtained by the combined measurement of the estimated liquid flow rate and estimated gas flow rate are less than 1.08%and 14.29%,respectively;the measurement error under slug flow condition of the liquid volume fraction and gas volume fraction were within±4.85%and±21.61%,respectively.The relative error of total flow measurement was within±4.26%.The relative error of the volume flow measurement obtained by the combined measurement of the liquid flow rate and gas flow rate are less than±4.46%and±23.34%,respectively.The experimental results show that the design of the new device is reasonable and the measurement accuracy is high.The paper makes a targeted analysis of the two-phase interface,and proposes improvement ideas for follow-up experimental research.