A Model To Calculate the Theoretical Critical Flow Rate Through Venturi Gas Lift Valves

SPE Journal ◽  
2010 ◽  
Vol 16 (01) ◽  
pp. 134-147 ◽  
Author(s):  
Alcino R. Almeida
Keyword(s):  
Heat Capacity ◽  
Natural Gas ◽  
Flow Rate ◽  
Ideal Gas ◽  
Isobaric Heat Capacity ◽  
Critical Conditions ◽  
Critical Flow ◽  
Critical Flow Rate ◽  
Gas Lift ◽  
The Ideal

Summary A model to calculate the theoretical critical flow rate of nitrogen (N2) or natural gas through a Venturi gas lift valve is described herein. This new model considers real-gas effects not only in density calculations but also in other thermodynamic properties that are relevant during gas isentropic evolution. For the properties of N2, the Bennedict, Webb, and Rubin (BWR) equation of state and an accurate correlation for the ideal-gas isobaric heat capacity were used. For natural gas, the Dranchuk and Abou-Kassem equation, which reproduces the well-known Standing and Katz chart, was used, and, for the ideal-gas isobaric heat capacity, it was assumed that the natural gas was a mixture of methane and ethane only, their individual ideal-gas heat capacity being calculated by updated correlations. To validate the use of the proposed equations of state, a comparison of calculated with experimental or reference data on properties of N2 and natural gas (including pure methane and some relevant mixtures) was performed with very good results for N2 and for natural-gas compositions usual in gas lift operations (dry gas with very small amounts of contaminants). For natural gas with moderate amounts of N2 and carbon dioxide (CO2), accurate results were obtained after correction of critical conditions and of ideal heat capacity. The model was also compared with other theoretical models found in the literature, which use compositional approaches for natural gas, with excellent results. Some experimental results obtained with commercial Venturi valves manufactured in Brazil are also presented.

Calculation of the Theoretical Critical Flow Rate of Saturated Steam

1982 ◽  
Vol 104 (1) ◽  
pp. 211-214
Author(s):  
J. W. Murdock
Keyword(s):  
Flow Rate ◽  
Critical Pressure ◽  
Theoretical Method ◽  
Ideal Gas ◽  
Saturated Steam ◽  
Critical Flow ◽  
Maximum Deviation ◽  
Average Deviation ◽  
Flow Rates ◽  
Critical Flow Rate

This paper is concerned with the computation of the theoretical critical flow of dry saturated steam through passages over a range of 1 psia (7 kPa) to the critical pressure of 3208.2 psia (22.12 MPa). Two computational methods are used: a theoretical method using ideal gas relations, and a flow maximization method using actual saturated steam properties. An equation is developed and based on the theoretical equation that yields flow rates that have an average deviation of 0.1 percent and a maximum deviation of 0.3 percent from the flow rate found by flow maximization. It is also demonstrated that Napier’s equation currently recommended by PTC 25.3-1976 “Safety and Relief Valves” is unsatisfactory for the calculation of theoretical critical flow rates.

scholarly journals Role of Shearing Dispersion and Stripping in Wax Deposition in Crude Oil Pipelines

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4325
Author(s):  
Zhihua Wang ◽  
Yunfei Xu ◽  
Yi Zhao ◽  
Zhimin Li ◽  
Yang Liu ◽  
...  
Keyword(s):  
Crude Oil ◽  
Flow Rate ◽  
Critical Flow ◽  
Wax Deposition ◽  
Dominant Effect ◽  
Critical Flow Rate ◽  
Oil Pipelines ◽  
Oil Flow ◽  
Shearing Mechanism

Wax deposition during crude oil transmission can cause a series of negative effects and lead to problems associated with pipeline safety. A considerable number of previous works have investigated the wax deposition mechanism, inhibition technology, and remediation methods. However, studies on the shearing mechanism of wax deposition have focused largely on the characterization of this phenomena. The role of the shearing mechanism on wax deposition has not been completely clarified. This mechanism can be divided into the shearing dispersion effect caused by radial migration of wax particles and the shearing stripping effect caused by hydrodynamic scouring. From the perspective of energy analysis, a novel wax deposition model was proposed that considered the flow parameters of waxy crude oil in pipelines instead of its rheological parameters. Considering the two effects of shearing dispersion and shearing stripping coexist, with either one of them being the dominant mechanism, a shearing dispersion flux model and a shearing stripping model were established. Furthermore, a quantitative method to distinguish between the roles of shearing dispersion and shearing stripping in wax deposition was developed. The results indicated that the shearing mechanism can contribute an average of approximately 10% and a maximum of nearly 30% to the wax deposition process. With an increase in the oil flow rate, the effect of the shearing mechanism on wax deposition is enhanced, and its contribution was demonstrated to be negative; shear stripping was observed to be the dominant mechanism. A critical flow rate was observed when the dominant effect changes. When the oil flow rate is lower than the critical flow rate, the shearing dispersion effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. When the oil flow rate is higher than the critical flow rate, the shearing stripping effect is the dominant effect; its contribution rate increases with an increase in the oil flow temperature. This understanding can be used to design operational parameters of the actual crude oil pipelines and address the potential flow assurance problems. The results of this study are of great significance for understanding the wax deposition theory of crude oil and accelerating the development of petroleum industry pipelines.

A NUMERICAL STUDY OF FLUID INJECTION AND MIXING UNDER NEAR-CRITICAL CONDITIONS

2012 ◽  
Vol 19 ◽  
pp. 39-49 ◽  
Author(s):  
HUA-GUANG LI ◽  
XI-YUN LU ◽  
VIGOR YANG
Keyword(s):  
Reynolds Number ◽  
Shear Layer ◽  
Numerical Study ◽  
Ideal Gas ◽  
Critical Conditions ◽  
Reference Case ◽  
Nitrogen Injection ◽  
Volume Dilatation ◽  
High Reynolds ◽  
The Ideal

Nitrogen injection under conditions in close vicinity of liquid-gas critical point is studied through numerical simulation. The thermodynamic and transport properties of fluid exhibit anomalies in the near-critical fluid regime. These anomalies can cause distinctive effects on heat transfer and hydrodynamics. To focus on the influence of the highly variable properties and avoid the difficulties encountered in modeling high Reynolds number flows, a relatively low injection Reynolds number is adopted. A reference case with the same configuration and Reynolds number is also simulated in the ideal gas regime. Full conservation laws, real-fluid thermodynamic and transport phenomena are accommodated in the model. The obtained results reveal that the flow features of the near-critical fluid jet are significantly different from the ideal gas case. The near-critical fluid jet spreads faster and mixes better with the ambient fluid compared to the ideal gas jet. It is also identified that vortex pairing process develops faster in the near-critical case than in the ideal gas case. Detailed analysis of data at different streamwise positions including both flat shear layer region and fully developed vortex region reveals the effect of volume dilatation and baroclinic torque plays an important role in the near-critical fluid case. The volume dilatation effect disturbs the shear layer and makes it more unstable. The volume dilatation and baroclinic effects strengthen the vorticity and stimulate the vortex rolling up and pairing process.

Numerical Simulation of Vibration of Composite Pipelines Conveying Pulsating Fluid

2019 ◽  
Vol 11 (09) ◽  
pp. 1950090 ◽  
Author(s):  
B. A. Khudayarov ◽  
KH. M. Komilova ◽  
F. ZH. Turaev
Keyword(s):  
Internal Pressure ◽  
Galerkin Method ◽  
Flow Rate ◽  
Pulsating Flow ◽  
Integral Model ◽  
Rheological Parameters ◽  
Critical Flow ◽  
Critical Flow Rate ◽  
Weakly Singular ◽  
Pulsating Fluid

Vibration problems of pipelines made of composite materials conveying pulsating flow of gas and fluid are investigated in the paper. A dynamic model of motion of pipelines conveying pulsating fluid flow supported by a Hetenyi’s base is developed taking into account the viscosity properties of the structure material, axial forces, internal pressure and Winkler’s viscoelastic base. To describe the processes of viscoelastic material strain, the Boltzmann–Volterra integral model with weakly singular hereditary kernels is used. Using the Bubnov–Galerkin method, the problem is reduced to the study of a system of ordinary integro-differential equations (IDE). A computational algorithm is developed based on the elimination of the features of IDE with weakly singular kernels, followed by the use of quadrature formulas. The effect of rheological parameters of the pipeline material, flow rate and base parameters on the vibration of a viscoelastic pipeline conveying pulsating fluid is analyzed. The convergence analysis of the approximate solution of the Bubnov–Galerkin method is carried out. It was revealed that the viscosity parameters of the material and the pipeline base lead to a significant change in the critical flow rate. It was stated that an increase in excitation coefficient of pulsating flow and the parameter of internal pressure leads to a decrease in the critical flow rate. It is shown that an increase in the singularity parameter, the Winkler base parameter, the rigidity parameter of the continuous base layer and the Reynolds number increases the critical flow rate.

Effect of Non-Condensible Gas on the Subcooled Water Critical Flow in a Safety Valve

2002 ◽  
Author(s):  
Se Won Kim ◽  
Sang Kyoon Lee ◽  
Hee Cheon No
Keyword(s):  
Flow Rate ◽  
Critical Pressure ◽  
Safety Valve ◽  
Pressure Ratio ◽  
Water Flow Rate ◽  
Critical Flow ◽  
Inlet Temperature ◽  
Nitrogen Gas ◽  
Critical Flow Rate ◽  
Subcooled Water

The effect of non-condensable gas on the subcooled water critical flow in a safety valve is investigated experimentally at various subcoolings with 3 different disk lifts. To evaluate its effect on the critical pressure ratio and critical flow rate, three parameters are considered: the ratios of outlet pressure to inlet pressure, the subcooling to inlet temperature, and the gas volumetric flow to water volumetric flow are 0.15–0.23, 0.07–0.12, and 0–0.8, respectively. It turns out that the critical pressure ratio is mainly dependent on the subcooling, and its dependency on the gas fraction and the pressure drop is relatively small. When the ratio of nitrogen gas volumetric flow to water volumetric flow becomes lower than 20%, the subcooled water critical flow rate is decreased about 10% compare to the water flow rate of without non-condensable gas. However, it maintains a constant value after the ratio of gas volumetric flow to water volumetric flow becomes higher than 20%. The subcooled water critical flow correlation, which considers subcooling, disc lift, backpressure, and non-condensable gas, shows good agreement with the total present experimental data with the root mean square error 8.17%.

Critical flow rate of anode fuel exhaust in a PEM fuel cell system

2006 ◽  
Vol 156 (2) ◽  
pp. 512-519 ◽  
Author(s):  
Wenhua H. Zhu ◽  
Robert U. Payne ◽  
Bruce J. Tatarchuk
Keyword(s):  
Fuel Cell ◽  
Flow Rate ◽  
Pem Fuel Cell ◽  
Cell System ◽  
Critical Flow ◽  
Fuel Cell System ◽  
Critical Flow Rate
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