2 and 3-phase flow

Multiphase flow occurs when two or more phases are flowing along a closed or open pipe. The phases may be gas, liquid or solid and two and three phase flow are common (as well as multiple component flow due to immiscibility in the liquids more that one liquid phase may exist). Hence in the “fluid” flowing down the pipe the phases may be fully mixed, fully separated and anything in between depending on the nature and densities of the phases, the degree of turbulence induced in the mixture and the physical geometry of the pipe.

Add to this the boundary layer effect at the pipe walls and it is a very complex measurement challenge.

Knowing process flow conditions can be used to manage downstream processes. It would be highly beneficial to measure the flow of each phase in the pipe, ideally mass and volume, and the degree of mixing within the pipe. This is not possible from within the pipe as the very act of measurement disturbs the flow; hence it has to be from outside the pipe.

Most of the current research and measurement systems rely on flow regime pre-determination, assumption or computational models.

There is a well defined need in knowing with certainty process conditions to improve efficiency and quality as well as reducing processing costs. It would be highly beneficial to measure the flow of each phase in the pipe, ideally mass, volume, phase inversion and the degree of mixing within the pipe.

Oil & gas companies are particularly interested in knowing which flow regimes (stratified, bubble flows, etc) they are working under at a certain time of their process. There is also growing academic and industrial interest in oil sands research where once again visibility is reduced due to stainless steel equipment or opaque material (sand in heavy oil). Additionally there is a need to learn more about wet gas flow behavior to improve understanding of meter performance.

Organizations from the mining and environmental sectors are involved in water based slurry research looking at the concentration, settlement and velocity of solids transported down a pipe by the liquid phase. This also provides a better understanding of corrosion effects.

Applications:

• Multiphase Flow Measurement
• Two phase/Three phase
• Solid/Liquid/Gas
• Lab/Pilot/Production
• Research/Process Monitoring
• Process Development

From the early 1980’s the petrochemical sector has invested in process tomography to provide information on multi-phase flows.  As noted above, this is an extremely challenging measurement objective and it is only recently that significant advances in software, sensors and instrumentation technology have led to process benefits.

Flow processes may involve a variety of phases or components in the gas, liquid or solid phase and are complex in their nature. Electrical tomography techniques provide the capability for flow visualisation, regardless of material opacity, to enhance

the understanding of such complex flow processes.

ITS instrumentation can be used to visualise a range of multiphase systems including:

• Liquid-liquid
• Solid-liquid
• Gas-liquid

Water-air flow:

Multiple modalities (of capacitance and resistance tomography) have been fused to provide information on two and three phase flow. Resistance tomography provides data on water / oil-gas components and capacitance provides data on water-oil / gas components.  By taking data contemporaneously, full three phase flow information can be provided, such as air/oil/water.

• At a simpler level of instrumentation, robust sensors have been deployed in marine applications (in deserts / beaches) to provide information on solids flowing during dredging applications
• In addition, advances in cross-correlation have combined with advances in very high speed data collection to provide the cornerstones for mass flow measurement.

Process tomography can provide information on:

• Volume fractions
• Relative concentrations
• Monitor phase inversion 

Key benefits include:

• Determine flow conditions

• Monitor phase inversion

• Investigates flow rates of multi-component flow

• Characterise flow regimes

• Accurate measurement of multiphase flow

Register to access our "Flow" case studies available from the Download section on the right.

Publications:

Hua Li, Wang, Mi, Ying-Xiang, Wu and Lucas, Gary (2008) Volume Flow Rate Measurement in Vertical Oil in-water Pipe Flow using Electrical Impedance Tomography and a Local Probe, 11th Int. Conf. on Multiphase Flow in Industrial Plants, Palermo, Italy

Giguére, R., Fradette, L., Mignon, D. and Tanguy, P.A. (2008) Characterisation of slurry flow regime transitions by ERT, Chemical Engineering Research and Design, Vol. 86, pp 989-996 Giguére, R., Fradette, L., Mignon, D. and Tanguy, P.A. (2008) ERT algorithms for quantitative concentration measurement of multiphase flows, Chemical Engineering Journal, Vol. 141, pp 305-317

Henningsson, M., Regner, M., Ostergren, K., Tragardh, C. and Dejmek, P. (2007) CFD simulation and ERT visualization of the displacement of yoghurt by water on industrial scale, Journal of Food Engineering, Vol.80, No. 1, pp 166-175

Pullum, L, Graham, L, Rudman, M and Hamilton, R (2005) High concentration suspension monitoring,Minerals Engineering, 19, 471-477

Wu, Y., Li, H., Wang, M. and Williams, R.A. (2005) Characterisation of air-water two-phase vertical flow using electrical resistance imaging, The Canadian Journal of Chemical Engineering, Vol. 83, February 2005

Wang, M. (2005) Impedance mapping of particulate multiphase flows, Flow Measurement and Instrumentation, Vol. 16 Henningsson, M., Östergren, K. & Dejmek, P. (2005) Plug flow of yoghurt in piping as determined by cross correlated dual-plane electrical resistance Tomography, Journal of Food Engineering

Wang, M., Jones, T.F. and Williams, R.A. (2003) Visualisation of asymmetric solids distribution in horizontal swirling flows using electrical resistance tomography, Trans IChemE, Volume 81, Part A, pp854-861

Graham L, Hamilton R, Rudman M, Strode P and Pullum L (2002) Coarse solids concentration profiles in laminar pipe flow, Hydrotransport 15, Banff, Canada, June 2002

White RB, Simic K and Strode PR (2001) The combined use of flow visualisation, electrical resistance Tomography and computational fluid dynamic modelling to study mixing in a pipe, 2nd World Congress of Industrial Process Tomography, Hannover, Germany, 29-31st August 2001

Qiu, C, Hoyle, BS and Podd FJW (2007) Engineering and application of a dual-modality process tomography system, Flow Measurement and Instrumentation, Vol. 18, 247-254

Qiu, CH, Bagatin, R, Palmery, S and Bolton GT (2007) On-line visualization of asymmetric multi-phase flow in an industrial flow loop using electrical tomographic techniques, Proceedings of the 5th World Congress onIndustrial Process Tomography, Bergen, Norway, 3-6 September 2007

For more information about this paper, please contact ITS.

In the Press:

• Petroindustry News - Annual Buyers Guide 2010 - An Oil Company Used Dual-modality ECT and ERT to Study the Flow of Multiphase Oil-water-gas Systems Reducing Energy Costs and Improving Plant Yields
• The Chemical Engineer Feb 2009 - Seeing is believing
• Japanese Journal of Multiphase Flow vol 23 N1- 2009 - (in Japanese)
• Engineering Talk - Oct 2008 - Tomography System captures speedy flow - z8000
• Flowcontrolnetwork.com - Aug 2007 - Considering Multiphase Flow

If you would like to receive a copy of an article, please contact ITS