Effect of second phase on single phase flow meters in steam quality measurement


  • M Pusayatanont
  • P Unsworth




This paper presents results from an investigation of the two phase flow, especially liquid ingas phase, in most mainly used flow meter in steam industry namely differential pressuremeter is investigated. As in general, a flowmeter is designed and employed to measure flowrate of single phase fluid. There are many types of meter available in the market characterizeby their working principles, installed conditions and measured fluid. All meters representtheir accuracies under the single phase flow condition. However, when they are working inunusual conditions especially under multiphase flow, most meters lose their accuraciessignificantly even there is small amount of second phase introduced into the system. Tounderstand the deteriorated performance of the meter under two phase flow, additional studyon the effect the second phase on the meter is required.The laboratory experiment is set up to simulate the wet steam by flowing compressed airin the 2 inch pipe. Water droplet is generated by pressurized water flowing through a nozzleand then spayed into the system in range of 25% maximum by mass fraction. The signal fromeach flowmeter is collected by digital computer and analyzed using FFT and power spectrumdensity. The results show that the presence of the second phase in the system causes highfrequency fluctuation and causes significant error on meter reading. Flow manufacturersalways add low-pass filter circuit to remove this high frequency signal, however, this papershows that the high frequency signal in specific region is useful as it can be use to estimatedthe percentage of the second phase in the main phase system.


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How to Cite

Pusayatanont, M. and Unsworth, P. (2009) “Effect of second phase on single phase flow meters in steam quality measurement”, The International Journal of Multiphysics, 3(1), pp. 73-80. doi: 10.1260/175095409787924508.