2 and 3-phase flow

Multiphase flow occurs when two or more discrete phases are flowing in a closed pipe or mixing in a vessel. In the case of mixing and reactions in a vessel, these are dealt with under Mixing.  The phases may be gas, liquid or solid and two and three phase flow are common (as well as multiple component flow) In addition, different immiscible liquids or solids can also be present in multiple phase flows. 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 and the degree of turbulence in the mixture.

Add to this the boundary layer effect at the pipe walls and understanding multiphase flows represents a very challenging field.

Knowing flow conditions can help manage downstream processes.It is highly beneficial to measure the flow of each phase in a pipe, ideally mass and velocity, as well as the extent of mixing. This is not possible from within the pipe as the act of measurement disturbs the flow; hence sensors need to be non-intrusive.

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

There is a well definedneed in knowing with certainty process conditions to improve efficiency and qualityas well as reducing processing costs. Key process features include measuring flow of each phase in the pipe, extent of mixing / separation and phase inversion 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.  Particularly as visibility is reduced due to stainless steel equipment and opaque materials (sand in heavy oil). Additionally there is a need to learn more about wet gas flow behavior to improve understanding of meter performance and deal with waxing and similar phenomena.

Organizations from the mining and environmental sectors are also 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 and erosion effects.

Applications:

• Multiphase Flow Measurement (such as gas / oil / water)
• Two phase/Three phase
• Solid/Liquid/Gas (including heterogeneous catalysis)
• 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. These are complex in their nature.

Electrical tomography techniques provides 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 through the difference in electrical properties of each phase.  The technology has been successfully deployed on:

• Liquid-liquid flows
• Solid-liquid flows
• Gas-liquid flows
• Three phase flows of oil / water / gas

Water-air flow on inclined flow loop:

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 and non-conductive components (oil / gas) and capacitance provides data on water-oil / gas components by selecting appropriate thresholds.  By taking data contemporaneously, full three phase flow information can be provided, such as gas/oil/water.

ITS has designed both capacitance and resistance tomography sensors to operate high pressure pipes (up to 200bar) and explosive atmospheres.

• 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 temporal and spatial information on::

• Volume fractions and relative concentrations
• Flow state
• 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