Performance analysis of an ejector for flare gas recovery
TL;DR: In this article, a numerical analysis was performed to evaluate the performance of an ejector for flare gas recovery application, and the role of setback distance on the location of jet breakup was presented.
Abstract: The simplicity, reliability and cost-effectiveness of ejector-based technologies have paved way to recover low-pressure gases which are normally flared by the oil companies. In this study, a numerical analysis was performed to evaluate the performance of an ejector for flare gas recovery application. Initially water was used as the primary fluid and air as the secondary fluid. The analysis was then extended to different combinations of primary and secondary fluids, namely, water–methane, crude oil–air and crude oil–methane, respectively. The governing equations of fluid flow were solved for both liquid and gas phases. The entrainment and pressure ratio varied as the design parameters and operating conditions were changed. The role of setback distance on the location of jet breakup was presented. Primary flow rate optimization was done to find the maximum flow rate for the design as the best performance can be obtained at that flow rate. The optimum setback distance and the flow rate of the primary fluid w...
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TL;DR: In this article, the use of an integrated gas-gas ejector system instead of a compressor is proposed and studied technically and economically in a typical oil refinery plant, with an investment cost of 4.84 $M and accepted payback period of 2 years and the recovery of approximately 90% flare gas volume during normal operation.
23 citations
TL;DR: In this paper , a pneumatic shooting technology consisting mainly of a nozzle, shell and acceleration tube was designed, and the response-surface methodology of structure parameters and CFD simulation technology was adopted in this work.
Abstract: In rice–wheat rotation areas of China, traditional wheat seeders have severe blockage, low working efficiency and poor seeding quality. In this study, a pneumatic shooting technology was designed, consisting mainly of a nozzle, shell and acceleration tube. To improve the sowing depth of the pneumatic shooting device, the response-surface methodology of structure parameters and CFD simulation technology was adopted in this work. The effects of working pressure, acceleration-tube diameter and throat distance on the steady airflow length (SAL) and steady airflow velocity (SAV) were studied by airflow field analysis, and the response-surface method was introduced to obtain the optimal parameter combination of the pneumatic shooting device for wheat. The optimal parameter combination was working pressure 686 kPa, acceleration tube diameter 8 mm and throat distance 20 mm. The simulation result showed that the optimized device of pneumatic shooting performs faster and has more stable airflow field characteristics in comparison to the initial device. The field test demonstrated that the optimized device has about 68% higher seeding depth than the initial device. The average field-seeding depth of the optimized device was 19.95 mm, which is about 68% higher than the initial device. The emergence rate for the optimized device was about 88.7% without obvious reduction. CFD and response-surface methods positively affect the optimization of pneumatic wheat-shooting devices, and the significance was also confirmed.
7 citations
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TL;DR: In this article, an improved analytical treatment is developed which makes possible the satisfactory prediction of the liquid velocity distribution in two-phase bubble flow, and the agreement between the measured velocity profiles and those calculated is quite close especially in the core region of a duct.
530 citations
TL;DR: In this article, the role of streamwise vortex structures in the near-field (x/d < 10) evolution of a round jet is examined, and it is shown that the efficiency of the streamwise vorticity in entraining fluid increases relative to that of the azimuthal Vorticity.
Abstract: The role of streamwise vortex structures in the near-field (x/d < 10) evolution of a round jet is examined. In free shear layers the streamwise vorticity develops into Bernal-Roshko structures which are streamwise vortex pairs. Similar structures are shown to exist in round jets. These structures, which evolve and amplify in the braid region between primary vortical structures, are shown to drastically alter the entrainment process in the near field and to increase the rate at which fluid is entrained into the jet. As the flow evolves downstream, the efficiency of the streamwise vorticity in entraining fluid increases relative to that of the azimuthal vorticity. Beyond the end of the potential core regime, the entrainment process is mainly controlled by streamwise vorticity. These processes are identified via flow visualization and confirmed by detailed global entrainment measurements.
477 citations
"Performance analysis of an ejector ..." refers background in this paper
...Experimental studies were undertaken by Sene (1988), Zhu, Oguz, and Prosperetti (2000), Liepmann and Gharib (1992), Capone, Soldati, and Romano (2013), Tafreshi and Pourdeyhimi (2003) and Morozumi and Fukai (2004) to understand the underlying mechanism of this entrainment....
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TL;DR: In this article, an Eulerian multidimensional two-fluid model for a cylindrical two-phase dispersed particle jet is proposed and compared with experimental data, where the averaged conservation equations of mass and momentum are solved for each phase and the turbulent kinetic energy equation is solved for the continuous phase.
144 citations
"Performance analysis of an ejector ..." refers methods in this paper
...The Bertodano model (De Bertodano, 1998) with a dispersion coefficient of 0.1 and the Sato enhanced eddy viscosity model (Sato & Sekoguchi, 1975) were used to model this effect....
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...The turbulent dispersion force, derived by De Bertodano (1998), is represented by FTD ¼ 2CTDrl k7al: ð4Þ The governing equations for the turbulent kinetic energy ‘k’ and turbulent dissipation rate ‘1’ are 7· al rlulkl 2 ml þ mtl skRNG 7k ¼ alðG2 rlal1Þ; ð5Þ 7·ðalrlul1Þ ¼ 7· al ml þ mtl s1RNG 71 þ…...
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...The turbulent dispersion force, derived by De Bertodano (1998), is represented by...
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TL;DR: In this paper, it is shown that, provided the nozzle from which the jet issues is properly contoured, an undisturbed jet does not entrap air even at relatively high Reynolds numbers.
Abstract: The process by which a liquid jet falling into a liquid pool entrains air is studied experimentally and theoretically. It is shown that, provided the nozzle from which the jet issues is properly contoured, an undisturbed jet does not entrap air even at relatively high Reynolds numbers. When surface disturbances are generated on the jet by a rapid increase of the liquid flow rate, on the other hand, large air cavities are formed. Their collapse under the action of gravity causes the entrapment of bubbles in the liquid. This sequence of events is recorded with a CCD and a high-speed camera. A boundary-integral method is used to simulate the process numerically with results in good agreement with the observations. An unexpected nding is that the role of the jet is not simply that of conveying the disturbance to the pool surface. Rather, both the observed energy budget and the simulations imply the presence of a mechanism by which part of the jet energy is used in creating the cavity. A hypothesis on the nature of this mechanism is presented.
122 citations
"Performance analysis of an ejector ..." refers background in this paper
...Experimental studies were undertaken by Sene (1988), Zhu, Oguz, and Prosperetti (2000), Liepmann and Gharib (1992), Capone, Soldati, and Romano (2013), Tafreshi and Pourdeyhimi (2003) and Morozumi and Fukai (2004) to understand the underlying mechanism of this entrainment....
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TL;DR: In this paper, the authors described a theoretical and experimental study of the mechanisms by which plunging jets entrain air followed other workers, it is proposed that the mechanism of air entrainment undergoes a qualitative change as the jet impact velocity (U i ) is increased.
105 citations
"Performance analysis of an ejector ..." refers background in this paper
...Experimental studies were undertaken by Sene (1988), Zhu, Oguz, and Prosperetti (2000), Liepmann and Gharib (1992), Capone, Soldati, and Romano (2013), Tafreshi and Pourdeyhimi (2003) and Morozumi and Fukai (2004) to understand the underlying mechanism of this entrainment....
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