AN EXPERIMENTAL ANALISYS OF ORIFICE PLATE WET GAS METER BY THIRD PRESSURE TAPPING FOR LIQUID LOADING ESTIMATION
Name: RENAN FÁVARO CALIMAN
Type: MSc dissertation
Publication date: 18/07/2022
Advisor:
Name |
Role |
|---|---|
| ROGÉRIO RAMOS | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| MARCIO FERREIRA MARTINS | Internal Examiner * |
| ROGÉRIO RAMOS | Advisor * |
Summary: Wet gas flows are very common in many industrial processes, manly in oil industries. On those, flow measurement is based in differential pressure devices at least on 40% of the cases, being the orifice plate the most used one, reaching US$ 21 billion in natural gas measurement at UK industry according to Reader-Harris, Forsyth, and Boussouara (2021). However, in case of two-phase applications, the liquid loading causes a positive bias on the pressure differential readings, due to phases interactions called over-reading and resulting in an erroneous gas flow rate prediction up to 50%. Through decades apart, many authors proposed correlations to estimate and correct this overestimation for different differential pressure devices, such as orifice plates, venturi tubes and inverted cones, but all needed some liquid content information, which real time estimation is a engineering challenge. To overcome this barrier, industry has been developing an all in on two-phase wet gas flow meters (WGFMs), with liquid loading estimation and over-reading (OR) correction on the same meter. In 2012, ISO TR 11583 (2012) released a methodology to wet gas measurement based on orifice plates or Venturi, using the pressure loss ratio (PLR) technique to liquid content relationship limited by 6D 3rd pressure tap, high pressure levels and low gas wetness. Aiming to investigate this methodology, this work relied on a gas-liquid flow circuit, located at the Research Group for Studies on Oil&Gas Flow and Measurement (NEMOG, in Portuguese), located at Federal University of Espírito Santo, Vitória, Brazil, to promote an air-water flow at 1.3 and 5 barg pressure line (density ratio - DR equal to 0.0025, 0.0048 and 0.0071), 360 kg/h air mass flow rate (Gas Froude number FRg equal to 0.74, 0.90 and 1.29) and Lockhart-Martinelli parameter XLM equal to 0.15 ,0.22 and 0.30 levels. With this data, the most relevant orifice plate OR correlations were tested, considering ISO TR 11583 (2012) proposal and new data fitted equations are proposed for 6D, 20D and 144D third tap distances. Finally, a new methodology is proposed by combining ISO TR 11583 (2012) and Petalas and Aziz (1998) two-phase pressure drop model.
Key words: Wet gas, orifice plate, over-reading, pressure loss ratio, Lockhart-Martinelli
