35 th Gas-Lift Workshop Houston, Texas, USA February 6 10, 2012 Gas-liquid flow optimization with a Bubble Breaker device Hendy T. Rodrigues, Petr. Eng. Petrobras Research Center Feb. 6-10, 2012 2012 Gas-Lift Workshop 1
Petrobras R&D Center, Rio de Janeiro Feb. 6-10, 2012 2012 Gas-Lift Workshop 2
Introduction Bubble breaker was first presented by Shell engineers (Schrama and Fernandes, 2005): Experimental and field tests Objective is to break the bubbles into smaller diameters, or change the flow pattern
Motivation Smaller bubbles reduce hidrostatic pressure drop and delay the transition to slug flow (Guet et. al., 2003)
Motivation Lower rise velocity Greater void fraction lower hidrostatic pressure gradient. ρ = ρ α + ρ 1 G L ( α ) α = Q G A V G
Motivation Bubble rise velocity increases with bubble diamenter. D~1,5mm D~17mm (Celata et. al., 2007) (Parkinson et. al., 2008) (Tomiyama et. al., 2002) (Nguyen et. al., 1998)
Experiments This work presents experimental results to evaluate the device: Pressure measurements: At four locations along the pipe. Ratio of Pressure Gradients before and after the bubble breaker. R=(Press. Grad. After)/(Press. Grad. Before) Detailed videos: high-speed camera.
Experimental facilities
Bubble breaker 3 different geometries: 1 plate with orifices and 2 Venturi
Test conditions Test conditions: 1000 Q L = 6 21 L/min Q G = 9 90 L/min Air and water QL (L/min) 100 Disperse bubbles 10 Slug 1 1 10 100 1000 QG (L/min)
Videos Dispersed bubbles One elongated bubble Slug flow
Pressure loss results 1.0 0.8 QL=6 L/min Orifícios 8x3mm Venturi 8,5mm Venturi 6mm 1.0 0.8 QL=12 L/min Orifícios 8x3mm Venturi 8,5mm Venturi 6mm P (kgf/cm2) 0.6 0.4 P (kgf/cm2) 0.6 0.4 0.2 0.2 0.0 0 20 40 60 80 0.0 0 20 40 60 80 QG local (l/min) QG local (l/min) 1.0 0.8 QL=16,8 L/min Orifícios 8x3mm Venturi 8,5mm Venturi 6mm 1.0 0.8 QL=21 L/min Orifícios 8x3mm Venturi 8,5mm Venturi 6mm P (kgf/cm2) 0.6 0.4 P (kgf/cm2) 0.6 0.4 0.2 0.2 0.0 0 20 40 60 80 QG local (l/min) 0.0 0 20 40 60 80 QG local (l/min)
Pressure gradients ratio 1.6 1.6 QL=6 L/min QL=12 L/min 1.4 1.4 1.2 1.2 1.0 0.8 Orifícios 8x3mm Venturi 8,5mm Venturi 6mm 0.6 0 20 40 60 80 QG local (l/min) 1.6 1.4 QL=21 L/min Orifícios 8x3mm Venturi 8,5mm Venturi 6mm 1.2 R R R 1.0 0.8 Orifícios 8x3mm Venturi 8,5mm Venturi 6mm 0.6 0 20 40 60 80 QG local (l/min) 1.6 1.4 QL=16,8 L/min Orifícios 8x3mm Venturi 8,5mm Venturi 6mm 1.2 R 1.0 1.0 0.8 0.8 0.6 0.6 0 20 40 60 80 0 20 40 60 80 QG local (l/min) QG local (l/min) Values of R lower than 1 indicates that the Bubble Breaker is effective!
Results Bubble breaker is more effective at the Disperse Bubbles flow pattern (higher liquid flow rates). Geometry should be studied for each application. Reduction in the Pressure Gradients must be compared to local pressure drop. Next works: Different geometries to enhance bubble breaking while reducing local pressure drop.
References 1 Schrama, E. and Fernandes, R. The bubble breaker: breaking up slug flow into dispersed bubbly flow using a passive mechanical device. BHR Group 2005 Multiphase Production Technology 12 2 Guet, S., Ooms, G., Oliemans, R. V. A. and Mudde, R. F. Bubble Injector Effect on the Gaslift Efficiency AIChE Journal, Vol. 49, No. 9, 2003. 3 Celata, G. P., D Annibale, F., Di Marco, P., Memoli, G. and Tomiyama, A. Measurements of rising velocity of a small bubble in a stagnant fluid in one- and two-component systems Exp. Thermal and Fluid Sciences, Vol. 31, 2007. 4 Parkinson, L., Sedev, R., Fornasiero, D. and Ralston, J. The terminal rise velocity of 10 100 μm diameter bubbles in water Journal of Colloid and Interface Science, Vol. 322, 2008. 5 Tomiyama, A., Celata, G. P., Hosokawa, S. and Yoshida, S. Terminal velocity of single bubbles in surface tension force dominant regime Int. J. of Multiphase Flow, Vol. 28, 2002. 6 Nguyen, A. V. Prediction of Bubble Terminal Velocities in Contaminated Water AIChE Journal, Vol. 44, No. 1, 1998.
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