Measurement Features Of Axially-Installed Near Infrared Detector Gas-Liquid Two-Phase Flow

Gas-liquid two-phase,as the most common state in the nature,widely exists especially in petroleum,chemical,pipeline transport,nuclear reactors,and other fields,so the accurate measurement on the related parameters of gas-liquid two-phase flow is particularly significant.At present,near infrared absorption spectroscopy is mainly used for the measurement of phase density,and differential pressure technology is mainly adopted for flow measurement.Axially-installed near infrared sensor can effectively make the light sent out by near infrared emission device only be received by the corresponding probe,improve the measurement accuracy,reduce data redundancy,and enhance data validity.In measuring devices,pressure ports are increased to each variable diameter,and the differential values are extracted for flow measurement.The paper targets at gas-liquid two-phase flow measurement system,measuring device,pressure acquisition and storage system,optical signal acquisition as well as the establishment and calibration of processing system in axially-installed near infrared detector gas-liquid two-phase measurement system,and aims to ensure test results are effective and reliable.The relevant tests of single-phase water(0m3/h ~10m3/h)and single-phase gas(0m3/h ~30m3/h)were conducted in the testing system,and accurate measurement model was obtained.The relative error of single-phase water between measurement model and the actual value was within 1.25%,and the repeatability error was within 0.39%.Besides,the relative error of single-phase gas between measurement model and the actual value was within 1.5%,and the repeatability error was within 0.3%.On the basis of single-phase measurement,gas-liquid two-phase flow test was carried out.Phase density and flow of two-phase flow were respectively measured through voltage signal and differential pressure signal.In the two-phase test,water test range was 0.4 m3/h ~10 m3/h,and gas test range was 0.12 m3/h ~0.6 m3/h.in addition,65 operating points within the scope of the test were selected for testing,and phase density and flow measurement model was obtained.The relative error of phase density measurement model of slug flow and bubble flow respectively obtained according to the flow pattern was within 3%.At the same time,the calculation model applicable to both slug flow and bubble flow was established,and the model error was within 5%.Based on the known phase density,for the flow measurement model established through differential pressure signal and phase density,bubble flow total flow model error was within 6%;liquid-phase flow error was within 10%;the gas-phase flow error was within 20%.Slug flow total flow model error was within 1.6%;liquid-phase flow error was within 6%;the gas-phase flow error was within 10%.Axially-installed near infrared detector gas-liquid two-phase flow measurement system achieves the on-line measurement of dual parameters,namely phase density and flow,and it provides a new way of thinking for subsequent gas-liquid two-phase measurement.