Behavior and pressure drop of an upwardly two-phase flow through multi-hole orifices

Abstract

Experimental results on hydrodynamic behavior and pressure drop of two-phase mixture flowing upwardly in a pipe containing single- and/or multi-hole orifice plate are presented. It was found from the measurement of the void fraction upstream and downstream the orifices that the flow behavior is significantly affected by the layout of the orifice plate used and the flow starts to recover after approximately 7 D downstream the orifice. Furthermore, increasing orifice holes number results in decreasing the slip ratio. The standard deviation of the void fraction was used to identify the flow pattern before and after the orifices and found that the critical threshold transition occurred at a standard deviation of 0.2. The flow homogenization necessitates a minimum value of the liquid superficial velocity to occur, and the position where it takes place depends on this velocity and on the orifice holes number. It was also inferred from the two-phase pressure drop data across the orifices that three different flow regimes, where the transition between bubbly-to-slug and slug-to-churn flow, can be identified. An assessment of the predicted two-phase flow multiplier using some previous models dedicated to single-hole orifice was achieved; and found that the model proposed by Simpson et al. is the most reliable one. Single-phase pressure drop was also measured and compared with correlations from literature.

Theoretical study and experimental measurement of the gas liquid two-phase flow through a vertical Venturi meter

“…Figure 1 shows the experimental test rig. It is the same experimental test facility as that used previously by Zeghloul et al 31,32 The experiments were carried out by drawing tap water from the tank towards water flowmeters (rotameters) using a centrifugal pump from SAER ELETTROPOMPE. The latter was able to provide a total mass flow rate up to 40 m 3 /h.…”

“…Both air and water are mixed in the mixing unit and generate the air-water two-phase flow mixture. Details on the mixer unit are presented in the previous work of Zeghloul et al 32,33 Downstream the mixer, the air-water two-phase flow mixture flows through the Venturi in the vertical test section, then through a 90 bend, then a horizontal pipe section, and then a vertical 90 bend, then lastly to a vertical separating tank. The water flowed down through the bottom of the tank under the effect of gravity then recirculated again and the air is released into the atmosphere.…”

“…It is the same experimental test facility as that used previously by Zeghloul et al. 31,32…”

Study of the pressure drop in dust scrubber affected by liquid flowability

“…Research has shown that the results of gas-liquid two-phase studies can help significantly improve scrubber performance and ease the facility upsizing process. 14,15…”

“…Research has shown that the results of gas-liquid two-phase studies can help significantly improve scrubber performance and ease the facility upsizing process. 14,15 Additionally, studying the pressure drop will contribute to a better understanding of the energy consumption of dust scrubbers. Because the self-excited dust scrubber is a differential pressure (throttling) device, the primary portion of the energy (pressure drop) is consumed during the throttling process at the choke.…”