Lift Gas Flow Rate Research Articles

The Influence of Determining Factors on the Parameters of Gas-lift Operation of Flooded Gas Wells

The development of gas deposits at the final stage is usually complicated by watering production wells. With the advent of water in the formation product, the gas production rate decreases due to the decrease in the gas-saturated thickness of the reservoirs and the increase in pressure loss during movement of the liquid-gas mixture in the wellbore and flow lines as compared to the movement of gas only. Well operation is gradually becoming unstable, periodic with the subsequent cessation of natural flowing. The methods of operation of flooded wells are characterized. The use of the gas-lift method for the operation of flooded gas wells in depleted gas fields is justified. The effect of tubing diameter, wellhead pressure and water factor on the parameters of gas-lift operation of flooded wells is investigated. The research is carried out using the improved technique proposed by the authors and the PipeSim program for hypothetical (simulated) well conditions. The studies performed are presented in the form of graphical dependences of the production rate of reservoir gas, the minimum required gas production rate for the liquid to be taken from the bottom of the well to the surface, lift gas flow rate and bottomhole pressure on wellhead pressure, diameter of tubing and water factor. The research results indicate a significant coincidence of the values ​​of the calculated parameters of the gas-lift operation of the watered well according to the proposed methods and the PipeSim program. Using the research results, it is possible to select the optimal diameter of the tubing string and evaluate the value of formation gas flow rate and gas-lift flow rates for various values ​​of water factor and wellhead pressure.

Effect of gas-lift on liquefied petroleum gas (LPG) product yield: A case study of Chinarevskoe gas treatment unit (Kazakhstan)

More than expected increase of LPG yield was observed at the gas treatment unit after continuous gas-lift start up on Chinarevskoe oil field in western Kazakhstan. This paper studies the influence of gas-lift gas on fluid composition changes at separator conditions, and further, on LPG yield at the gas treatment unit. Gas-lift well operation and process plants simulations were carried out using Aspen HYSYS software and matched with real data from the field. Process simulation at constant separator pressure, varying temperatures, gas-lift gas flow rates and water cut indicated increase in LPG yield up to 4%. It was proofed that the increase of LPG yield did not come from propane and butanes from the gas-lift gas. It was concluded that increase of LPG yield is the consequence of mass transfer of components dissolved in oil, liquid, to the vapor phase, i. e. stripping of oil components by gas-lift gas as stripping medium took place. The amount of stripped components, and resulting LPG yield increase, at constant separator pressure on oil treatment plant depended on gas lift gas flow rate, temperatures and gas-lift gas composition. Presence of water had low impact on amounts of hydrocarbon components stripped from oil.

Cold Model-Based Investigations to Study the Effects of Operational and Nonoperational Parameters on the Ruhrstahl–Heraeus Degassing Process

The circulation rate of steel is known to play a vital role in the superlative performance of the Ruhrstahl–Heraeus (RH) degasser. Numerous experiments were conducted on a physical model for the RH degassing process, which was established at IEHK, RWTH-Aachen University. The model was developed with a scale ratio of 1:3 to study the RH process. This study is conducted to show the effects of operational and nonoperational parameters on the circulation rate of liquid water in the model. The effects of lift gas flow rate, submerged depth of snorkels, water level in vessel, etc. on the circulation rate are studied. The mixing characteristics are studied with the help of current conductivity experiments for different lift gas flow rates and water levels in the vacuum vessel. Finally, the relationship between dimensionless numbers is derived with the help of the experimental data obtained from the cold model.

Water Model on Fine Inclusion Removal by Bubble Flotation in RH Refining Process

With the development of socio-economic and science and technology, People are more strict to the requirement of steel quality. A physical model was established according to the “similarity theory” to simulate the real 180t RH-TB vacuum refining device. Liquid steel is simulated by Nacl solution, Fine inclusions is simulated by high density polypropylene less than 0.04mm in diameter. The influence regularity of treatment time, lift gas flow rate and method of addition, the amount and time of NaHCO3 addition on the inclusions removal rate have been discussed, the optimal values for each influence factor have been found and can be used in optimizing the refining technology.

Water Modeling Study on Removal of Inclusions in RH Degasser

A physical model was established according to the similarity theory to simulate the real 175t RH-TB vacuum refining device. Liquid steel is simulated by Nacl solution, the air is approximate argon and polypropylene simulate inclusions. The influence regularity of treatment time ,lift gas flow rate and submersion depth of snorkels on the inclusions removal rate have been discussed, the optimal values for each influence factor have been found and can be used in optimizing the refining technology.

Physical Simulation of Inclusions Removal in 180t RH Degasser

As one of the important refining equipments between steelmaking and continuous casting, RH vacuum refining plays an important role in removing the inclusions in the molten steel.RH can improve steel quality largely and meet the demand of mass production of high additional value. On the base of the similarity principle, a water model was developed to study the influence factors of inclusion removal in the molten steel of 180 tons RH vacuum refining device.Liquid steel is simulated by Nacl solution, the air is approximate argon, polypropylene simulate inclusions and NaHCO3 simulate composite particles. The influence regularity of lift gas flow rate, submersion depth of snorkels and the input amount of NaHCO3 on the inclusions removal rate have been discussed and the optimal values for each influence factor have been found.

Physical model of fluid flow characteristics in RH-TOP vacuum refining process

To understand the characteristic of circulation flow rate in 250-t RH-TOP vacuum refining process, the l:4 water model test was established through the bubble behavior and gas holdup in the up-leg to investigate the effects of different processes and equipment parameters on the RH circulation flow rate. With the increases of lifting gas flow rate, lifting bubble travel, and the internal diameter of the up-leg, and the decrease of nozzle diameter, the work done by bubble floatage and the circulation flow rate increase. The expression of circulation flow rate was derived from the regression analysis of experiment data. Meanwhile, the influences of vacuum chamber pressure and nozzle blockage situation on the circulation flow rate were discussed in detail by the bubble behavior and gas holdup in the up-leg. It is necessary to maintain a certain vacuum chamber liquid level in the molten steel circulation flow. Compared with a nozzle with symmetrical blockage in the up-leg, when a nozzle with non-symmetrical blockage is applied, the lifting gas distribution is non-uniform, causing a great effect on the molten steel circulation flow and making the circulation flow drop largely.

Numerical Modeling of Fluid Flow in RH Vacuum Refining Process

In this paper, the internal flow field of RH degasser was studied by numerical simulation. The range of the reasonable gas-inlet velocity which is related to the lift gas flow rate was obtained, then the results of two different gas-inlet velocities which are the reasonable velocity and the unreasonable velocity were chosen to be analyzed. Many vortexes and some differences of the flow fields were found in the RH degasser with the two different velocities. Through these results the development of the flow field could be got and it is valuable for the production in factory.

The Mixing Characteristics of Powder Injected through Top Lance in RH Degasser

With the increasing demand for high quality steel, various secondary refining techniques have been developed in the past decades. RH powder top blowing process (RH-PTB) is practiced in industry to decrease the impurity content of steel in a more economical way. In the present work, based on similarity theory, RH powder top blowing process was simulated by water model, and the effects of operating parameters on mixing time were investigated. The results show that the injected powder had a negligible effect on mixing time in RH-PTB, and the mixing time increases with top lance gas flowrate and decreases with lifting gas flowrate of up-leg. It was found that the mixing time was no longer decreasing as the lifting gas flowrate was over 15 L/min. Moreover, the height of top lance has some effect on mixing time in the reactor, and it should be adjusted to specific circumstances for purposes.

Water Model Study on Circulation Rate Influenced by Snorkel, Nozzle and Blowing Parameters in RH Refining

A water model of 1/4 linear scale for 210t RH has been established. RH circulation flow rate is measured by a velocimeter. The influences of lifting gas flow rate, snorkel inner diameter, injection depth and nozzle inner diameter on circulation rate were discussed. The dimension correlation has been calculated for the prediction of circulation rate. The results showed that the formula of circulation rate is 5.434×10-6G0.356·D1.254·d -0.106·H 0.821. The best nozzles inner diameter in terms of circulation rate was 3mm.

Simulation of Inclusions Removal Influenced by Snorkel and Blowing Parameters in RH Refining

In this paper the influence of snorkel length and snorkel inner diameter and lifting gas flow rate on inclusion removal rate are discussed. It is found that inclusion removal rate varies greatly with snorkel length and snorkel inner diameter. Prolonging the snorkel length is benefited for inclusions removal in RH and inclusion remove time is enhanced, but inclusion remove rate is decreased when snorkel inner diameter is reduced. There is a best lifting gas flow rate for inclusion removal.

Periodic flow characteristics during RH vacuum circulation refining

The circulation period of RH vacuum refining was studied to promote the refining efficiency. The influences of the lift gas flow rate and submersion depth of snorkels on the circulation period, and the relationship between mixing time and circulation flow were discussed. The effects of the lift gas flow rate and submersion depth on the degassing rate in one circulation period were studied by water modeling. The results show that the circulation period is shortened by increasing the lift gas flow rate. The circulation period is the shortest when the submersion depth of snorkels is 560 mm. The whole ladle can be mixed thoroughly after three times of circulation. Increasing the lift gas flow rate can enhance the degassing rate of RH circulation.

Numerical Simulation of the Multiphase Flow in the Rheinsahl–Heraeus (RH) System

Knowledge of gas–liquid multiphase flow behavior in the Rheinsahl–Heraeus (RH) system is of great significance to clarify the circulation flow rate, decarburization, and inclusion removal with a reliable description. Thus, based on the separate model of injecting gas behavior, a novel mathematical model of multiphase flow has been developed to give the distribution of gas holdup in the RH system. The numerical results show that the predicted circulation flow rates, the predicted flow velocities, and the predicted mixing times agree with the measured results in a water model and that the predicted tracer concentration curve agrees with the results obtained in an actual RH system. With a lower lifting gas flow rate, the rising gas bubbles are concentrated near the wall; with a higher lifting gas flow rate, gas bubbles can reach the center of the up-snorkel. A critical lifting gas flow rate is used to obtain the maximum circulation flow rate.

Mass Transfer Characteristics between Molten Steel and Particles under Conditions of RH-PB(IJ) Refining Process

The mass transfer characteristics between liquid steel and powder particles in RH-PB(IJ) refining process have been investigated on a water model of 1/4 linear scale for a 150 t multifunction RH degasser. Sodium chloride powder with analytical purity has been utilized as the flux for injection. The mass transfer coefficient (k) of solute (NaCl) in the liquid has been determined under the conditions of the RH-PB(IJ) process. The effects of the main technological and structural parameters on the characteristics have been examined. It may be concluded from the results that, under the conditions of the present work, the mass transfer coefficient in the liquid increases with increasing the lifting gas flow rate, with increasing the inner diameter of the upsnorkel, with increasing the circulation rate of the liquid, and with increasing the particle size of powdered flux, and decreases with an increase in the inner diameter of the downsnorkel. Its value is in the range of (3.392×10−5–2.661×10−4) m/s. The corresponding dimensionless relationships for the mass transfer coefficient in the range were obtained. Taking the relative velocity of the particles to the liquid into account, the mass transfer in the liquid may be characterized bySh=2+0.0285(Res)3/4Sc1/3Considering the energy dissipation caused by the fluctuation in the velocity of the liquid in turbulent flow, the following dimensionless relationship has been reached:Sh=2+0.0285(εsldp4/vl3)1/4Sc1/3When the mass transfer is regarded as that between rigid bubbles and molten steel, it may be characterized by:Sh=2+0.00731[Res0.48Sc0.339(g1/3dp/D2/3)0.072]1.455In comparison with the mass transfers coefficient in the molten steel between the powder particles and the liquid in RH-PTB process, that in the conditions of RH-PB(IJ) refining is smaller, being about 1/4–1/3 of the former, but the both have a similar feature and pattern.

Study on flow and mixing characteristics of molten steel in RH and RH-KTB refining processes

The flow and mixing characteristics of molten steel during the vacuum circulation refining, including RH(Ruhrstahl-Heraeus) and RH-KTB(Ruhrstahl-Heraeus-Kawasaki top blowing) processes, were investigated on a 1/5 linear scale water model of a 90 t multifunction RH degasser. The circulation rate was directly and more accurately determined, using a new method by which the more reliable results can be obtained. The fluid flow pattern and flow field in the ladle were demonstrated, observed and analyzed. The mixing time of liquid in the ladle was measured using electrical conductivity method. The residence time distribution in the RH model was obtained by tracer response technique. The influence of the main technological and geometric factors, including the gas top blowing (KTB) operation, was examined. The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula: Q lp=0.0333Q g 0.26 D u 0.69 D d 0.80 (t/min), where Q g - the lifting gas flow rate (NL/min); D u and D d - the inner diameters of the up and down-snorkels (cm), respectively. The maximum value of circulation rate of molten steel in the case of the 30 cm diameters either of the up-and down-snorkels for the RH degasser (the “saturated” rate) is approximately 31 t/min. The corresponding gas flow rate is 900 NL/min. Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing characteristics of the RH process under the conditions of the present work. There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process. A liquid-liquid two-phase flow is formed between the descending stream from the down-snorkel and the liquid around the stream. All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining. The correlation between the mixing time and the stirring energy density is τ m∞e −0.50 for the RH degasser. The mixing time rapidly shortens with an increase in the lifting gas flowrate. At a same gas flow rate, the mixing times with the up-and down-snorkel diameters either of 6 and 7 cm are essentially same. The 30 cm diameters either of the up-and down-snorkels for the RH degasser would be reasonable. The concentration-time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser.

Dynamic model for on-line observation of the current process state during RH degassing

Based on the principles of thermodynamics and reaction kinetics, a dynamic model for the vacuum circulation (RH) process was developed. It comprises decarburisation, oxygen removal, dehydrogenation, denitrogenation and the course of steel temperature. The process model was validated by comparison of simulation results with measured process data from the RH/1 plant of Voest Alpine Stahl Linz (VASL). At this plant, it is used for on-line observation of the contents of carbon, oxygen, hydrogen and nitrogen as well as the steel temperature. Based on cyclically measured values of vessel pressure, lift gas flow rate as well as waste gas flow rate and composition, the current heat status is calculated reliably. The accuracy of the carbon balance with measured waste gas values was improved remarkably by a model-based correction calculation. The on-line process observation system provides the operator with valuable information on the progress of vacuum treatment.

Mass transfer characteristics between molten steel and particles in RH–PTB refining

The mass transfer characteristics between powder particles and liquid steel in RH–PTB (powder top blowing) refining have been investigated on a ⅕ scale water model of a 90 t RH degasser. Sodium chloride powder of analytical purity has been used as the flux for blowing, and the mass transfer coefficient of solute (NaCl) in the liquid has been determined under the conditions of the RH–PTB process. The influence of the main technological and structural parameters on the mass transfer rate has been examined. The results have shown that, under the conditions of the present work, the mass transfer coefficient in the liquid increases with increasing lifting gas flowrate, with increasing inner diameter of the upsnorkel, with increasing circulation rate of the liquid, and with increasing particle size of powdered flux. On the other hand, mass transfer in the liquid decreases with an increase in the inner diameter of the downsnorkel. Its value is in the range (1·36–7·30) × 10−4 m s−1. The following dimensionless relationships, correspondingly, have been obtained for the mass transfer coefficient in the range:Sh = 2 + 0·073Re0·777s Sc1/3Sh = 2 + 0·073(ϵ1sd4p/ν3l)0·259 Sc1/3When the mass transfer is treated as that between rigid bubbles and molten steel, it may be characterised bySh = 2 + 0·026[Re0·48s Sc0·339(g1/3dp/D2/3p)0·072]1·455