Numerical Investigation of Nozzle Shape Effect on Shock Wave in Natural Gas Processing

Natural gas flow contains undesirable solid particles, liquid condensation, and/or oil droplets and requires reliable removing equipment to perform filtration. Recent natural gas processing applications are demanded compactness and reliability of process equipment. Since conventional means are sophisticated in design, poor in efficiency, and continue lacking robust, a supersonic nozzle has been introduced as an alternative means to meet such demands. A 3-D Convergent-Divergent Nozzle is simulated using commercial Code for pressure ratio (NPR) varies from 1.2 to 2. Six different shapes of nozzle are numerically examined to illustrate the position of shock-wave as such spot could be considered as a benchmark of particle separation. Rectangle, triangle, circular, elliptical, pentagon, and hexagon nozzles are simulated using Fluent Code with all have same cross-sectional area. The simple one-dimensional inviscid theory does not describe the actual features of fluid flow precisely as it ignores the impact of nozzle configuration on the flow properties. CFD Simulation results, however, show that nozzle geometry influences the flow structures including location of shock wave. The CFD analysis predicts shock appearance when p01/pa>1.2 for almost all geometry and locates at the lower area ratio (Ae/At). Simulation results showed that shock wave in Elliptical nozzle has the farthest distance from the throat among the others at relatively small NPR. As NPR increases, hexagon would be the farthest. The numerical result is compared with available experimental data and has shown good agreement in terms of shock location and flow structure.

Authors:

• Esam I. Jassim
• Mohamed M. Awad

Keywords:

• CFD
• Particle Separation
• Shock wave
• Supersonic Nozzle.

References:

[1] www.experimentation-online.co.uk/article.php?id=1390
[2] Lysne D., "An Experimental Study of Hydrate Plug Dissociation by
Pressure Reduction," Ph.D. Thesis, Norwegian Institute of Technology,
University of Trondhiem, 1995
[3] Moussa Kane, Aditya Singh, and Ronny Hanssen, "Hydrates Blockage
Experience in a Deep Water Subsea Dry Gas Pipeline: Lessons
Learned", at the 2008 Offshore Technology Conference held in Houston,
Texas, U.S.A., 5-8 May 2008.
[4] Lederhos J.P., Long J.P, Sum A., Christiansen R.L., Sloan E.D.,
"Effective Kinetic Inhibitors For Natural Gas Hydrates", Chemical
Engineering Science, 51(8), 1221-1229, 1996.
[5] Sloan E.D, "Fundamental principles and applications of Natural Gas
Hydrates", Nature Publication Group, 426, 353-359, Nov. 2003.
[6] Cottrll, A. "Technique puts gas treatment in a spin," Upstream, Mar. 19,
2004, p. 48.
[7] Okimoto, F., and Brouwer, J., "Supersonic gas condition," World Oil,
August 2002.
[8] VadimAlfyorov; Lev Bagirov; Leonard Dmitriev; Vladimir Feygin;
SalavatImaev; John R. Lacey, Supersonic nozzle efficiently separates
natural gas components, Oil and Gas Journal, volume 103, issue 20,
2005.
[9] Jassim E., AbedinzadeganAbdi M., and Muzychka Y., "Computational
Fluid Dynamics Study for Flow of Natural Gas through High Pressure
Supersonic Nozzles: Part 1- Real Gas Effects and Shockwave", Journal
of Petroleum Science and Technology, Vol. 26 issue 15, 1757-1772,
2008.
[10] Jassim E., AbedinzadeganAbdi M., and Muzychka Y., "Computational
Fluid Dynamics Study for Flow of Natural Gas through High Pressure
Supersonic Nozzles: Part 2- Nozzle Geometry and Vorticity", Journal of
Petroleum Science and Technology, Vol. 26 issue (15), 1773-1785,
2008.
[11] A.A.Khan and T.R. Shembharkar: Viscous flow analysis in a convergent
divergent Nozzle, Proc. Of the Int. Conf. on Aerospace Sci. and
Technology, June 26-28 2008, Bangalore, India
[12] M.V.Raman, C.S. Kumar and S. Elangovan: An experimental and
numerical investigation of supersonic contour nozzle flow separation,
Proceeding in the Int. Conf. on Aerospace Sci. and Technology, June 26-
28 2008, Bangalore, India.
[13] H. Mzad and M. Elguerri: Theoretical and experimental investigation of
compressible flow through convergent-divergent nozzles, Advanced
Materials Research,Vol 452-453 (2012),pp 1277-1285, Switzerland.
[14] D.Papamoschou, A.Zill and A.Johnson: Supersonic flow separation in
Planar Nozzles, Shock waves, Vol. 19/3 (2008), pp. 171-183.