STUDI EKSPERIMENTAL ALIRAN SLUG SEARAH KE BAWAH PADA PIPA VERTIKAL

In oil and gas industry, slug/plug flow are generally unwanted because they can create significant pressure fluctuations, and they can also lead to gas and liquid arriving at the processing facilities unevenly, causing tanks to flood. Since gas has lower density and therefore lower heat capacity than liquid, gas cool faster, so the temperature reduction during periods of high gas content can more easily cause hydrates to form. The increased intermittent liquid velocity can also accelerate corrosion. To have a better understanding of this phenomenon, experimental investigation of downward slug/plug flow was carried out in a 0.0191 m diameter pipe and the length of pipe is 8 m with water and air as process fluid. The objective of this experimental study is understanding the characteristics of downward slug flow with measuring plug velocity, void fraction, pressure, and film thickness. The superficial velocity of gas flow is observed from 0.22 m/s to 0.55 m/s. The superficial velocity of liquid flow is observed from 0.44 m/s to 1.1 m/s. The obtained data are taken at 2 m height over the outlet using digital camera which can record visual data with the frame rate is 240 fps. The obtained visual data are processed by image processing with MATLAB to observe film thickness, plug velocity, and void fraction accurately. Two nose form of plug is observed which is affected by two factors. The velocity of the liquid and the buoyancy induced velocity of the bubble. As a result, the amplitude of pressure fluctuations on low plug velocity is more significant than on high plug velocity. The nose of the plug tends to move towards the pipe wall if there is no entrainment bubbles after the nose of the plug