CFD simulation of flow through an orifice plate by using open source codes

Abstract EN

On the ground that the orifice plate is relatively inexpensive, requires very little maintenance and only calibrated during the occasion of plant turnaround, the orifice plate has turned to be in a real prevalent use in gas industry.

Inaccuracy of measurement in fiscal metering stations may highly be accounted to be the most vital factor for mischarges in natural gas industry in Libya.

A very trivial error in measurement can add up a fast escalating financial burden to the custodian transactions.

The unaccounted gas quantity transferred annually via orifice plates in Libya, could be estimated in an extent of multi-million dollars.

As the oil and gas wealth is the solely source of income to Libya, every effort now is being exerted to improve the accuracy of existing orifice metering facilities.

Discharge coefficient has become pivotal in current researches undertaken in this regard.

Hence, increasing the knowledge of the flow field in a typical orifice meter has been found to be imperative.

In this paper, flow phenomena for air passing through an orifice meter, were numerically analyzed with a complete package of open CFD source codes.

The simulation gave important information about the effect of flow parameters on the discharge coefficient for three different tappings locations representing flange tappings and D&D/2 tappings compared with vena contracta tappings.

Predicted discharge coefficients were paralleled also with discharge coefficients estimated by ISO 5167.

This study provided an applicable platform for a comparison of the flow through an orifice meter whose pipe diameter varying from 2, 4 and 6in, beta ratio of 0.15, 0.5 and 0.75 and Reynolds number of 18400, 54700 and 91100.

The results highlighted that the discharge coefficients were highly responsive to the variation of flow conditions and under all cases, the discharge coefficients for D&D/2 tappings were very close to that of vena contracta tappings which were believed as an ideal arrangement.

Also, the over-generalized statement articulating that the commercial codes were more accurate and less complex than the open source codes, might not be supported anymore