Vertical Pipe Research Articles

Experimental study on the effect of liquid properties on fluid behavior and liquid loading in vertical natural gas wells

Liquid loading is one of the major challenges for natural gas wells, as it can decrease and eventually cease the production of hydrocarbons. Characterizing liquid loading in gas wells and quantifying flow dynamics throughout this process is crucial. The literature shows a lack of experiments for oil-air low liquid loading flow, especially in vertical pipes. This demonstrates a lack of experimental data to comprehend the effect of liquid properties on two-phase flow behavior. In order to simulate a vertical natural gas well, oil-air tests were carried out in this work in a vertical pipe with a 0.0508-m ID (Inner-Diameter) under low liquid loading conditions. The aim of this study is to better comprehend the effect of liquid characteristics on flow behavior and the onset of liquid loading.The results of the experiments reveal that changing the liquid phase from water to oil reduces pressure loss, liquid holdup, and the surface gas velocity (vSg) at which liquid loading occurs. Liquid holdup and pressure loss of the water-air and oil-air flow with medium gas rates show notable variances within the churn flow. Additionally, compared to the minimum-pressure drop technique, the positive pressure technique offers considerably more reliable predictions for the start of liquid loading.Two models—the unified Tulsa University Fluid Flow Projects (TUFFP) and OLGA—are used to investigate the flow pattern, liquid holdup, and pressure loss predictions. The liquid film reverse, liquid droplet models, and the inflection point technique were compared to experimental data for similar liquid loading onset models by Alsanea et al. (2022). For the data in this investigation, the OLGA model and Coleman's correlation perform the best at predicting the onset of liquid loading. Given that both the unified model and OLGA use slug flow models, the results show that a separate model must be created for churn flow to accurately estimate the pressure drop and liquid holdup.

Application of moderate-temperature heat pipe instead of Ljungstrom in steam power plant: Parametric and Experimental study

The heat pipes are found as one of the promising technologies, which provide massive improvement of the energy performance in the energy systems. However, there are still some challenges in the employment of this technology in various applications, such as the ones with moderate-temperature operating conditions. The purpose of this study is the development of a moderate-temperature heat pipe on heat recovery, especially on replacing Ljungstrom in steam power plants with heat pipe heat exchangers. The temperature of the smoke passing through the Ljungstrom in the steam power plant is around 320 °C. For this purpose, 304 stainless steel vertical wickless heat pipe filled with special oil as working fluid is analyzed theoretically and experimentally. An experimental setup is fabricated, and the effects of aspect ratio, filling ratio, and exhaust temperature on the heat transfer rate and temperature distribution along the moderate-temperature wickless heat pipe are studied. Moreover, the operating limitations of the wickless heat pipe are investigated. A simple but accurate mathematical model is developed based on the equivalent thermal resistances and various physical limitations. By increasing the filling ratio of the heat pipe, the thermal performance of the system in all aspect ratios is reduced. The amount of heat transfer increased by increment of exhaust flow temperature up to 375 °C for aspect ratios of 11 and 25; however, for aspect ratio of 18, it is changed minimally. Based on the obtained results, the maximum heat transfer to cooling water, which is equal to 262.13 W, is achieved when FR and AR equal 30% and 18, consecutively. Furthermore, the average error for the equivalent thermal model is approximately 21% for a moderate-temperature wickless heat pipe, based on the assessment performed in this study.

Numerical analysis of encased granular pile with vertical hollow steel pipe

Numerical analysis of encased granular pile with vertical hollow steel pipe

Effects of liquid viscosity on interfacial and wall friction factors of swirling annular flows in a vertical pipe

Experiments of gas–liquid swirling annular flows in a vertical pipe of diameter D = 30 mm were carried out to obtain interfacial and wall friction factors, fi and fw, based on a three-fluid model. The liquid phase was two kinds of glycerol-water solutions with the kinematic viscosity νL of two or four times larger than that of water. Experimental data were obtained in two axial sections with short and long axial distances from the swirler, which corresponds to swirling and non-swirling annular flow regimes, respectively. Both the azimuthal and axial components of interfacial velocity decayed with increasing νL. The interfacial swirl number si, which is the ratio of the azimuthal component to the axial component of interfacial velocity, was not affected by νL for z*(=z/D) ≤ 3.8, where z is the axial coordinate in the test section. The mean interfacial swirl number si∗, which is the arithmetic mean of si in z* ≤ 3.8, was expressed in terms of dimensionless numbers based on the gas and liquid volumetric fluxes without νL. The interfacial friction factor decreased with increasing νL in swirling flows. The functional form of the Colebrook equation had a prospect of correlating fi in both swirling and non-swirling annular flows. The wall friction factor ratio of fw in the swirling annular flow regime to that in the non-swirling annular flow regime decreased as νL increased for si∗ > 0.33. The wall friction factor ratio was well correlated in terms of si∗ and νL.

Study on the Effective Well Depth of Single U-Shaped Vertical Buried Pipes Based on Temperature Difference Analysis.

A heat transfer model of a single U-shaped vertical buried pipe similar to an actual scenario is established, and the accuracy of the model is verified by experiments. The model is used to analyze the heat transfer performance of vertical buried pipe heat exchangers with well depths of 200, 160, 120, and 80 m. This includes the heat transfer per unit well depth, temperature change of the well wall and fluid along the pipe length, heat transfer coefficient, and section heat transfer validity. With the increase in well depth, the heat exchange per unit well depth decreases, and the proportion of heat exchange in the inlet section to the total heat exchange increases. When the well depths are 200, 160, 120, and 80 m, the last 10 m pipe sections have 30, 40.3, 53.7, and 66.4% of the heat exchange efficiencies of the initial 10 m pipe section, respectively. To obtain a reasonably effective well depth of a single U-shaped vertical buried pipe, it is necessary to comprehensively consider the heat exchange per unit well depth, the temperature difference between the well wall and the fluid, and the energy efficiency of the buried pipe section. Moreover, it should be analyzed in combination with economic factors.

Granular flow through a vertical axisymmetric pipe

Granular flow through a vertical axisymmetric pipe

Additional pressure loss coefficient of pneumatic conveying of moist-mixed materials for shotcrete based on CFD-DEM method

A systematic study of pressure loss through four common pipeline forms for pneumatic conveying of moist-mixed materials for shotcrete (horizontal straight pipes, vertical pipes, horizontal elbow, and vertical upward elbow) was conducted using CFD-DEM coupling. On-site experiments were conducted to verify the accuracy of the simulation. The research results showed that solid-gas ratio and moist-mixed materials for shotcrete have an influence on pipeline pressure loss. Furthermore, coefficients for additional pressure loss in horizontal and vertical pipes, and an equivalent horizontal length for both types of bends were established. Additionally, the spatial position and velocity of particles were examined under four conditions. The findings of this study have implications for the design and pressure loss estimation of pneumatic conveying pipelines for moist-mixed materials for shotcrete.

Investigation of particle size impact on dense particulate flows in a vertical pipe

In this work, a semi-resolved computational fluid dynamics-discrete element method is employed to study the effects of fluid–particle and particle–particle/wall interactions on particle mixing and segregation behaviors and particle dynamics with different particle sizes in a vertical pipe. There are two species of particles with the same density in the vertical pipe: d1 = 10 (species 1) and d2 = 2–7 mm (species 2), and species 2 contains both fine and coarse particles. The Stokes number Stp is introduced to characterize the effects of different particle sizes on particle dynamics. First, the particle mixing and segregation behaviors with different size ratios are qualitatively analyzed. By comparing with smaller size ratios, obvious granular plugs and stronger contact force networks occur at larger size ratios. Second, after the segregation of species 1 and 2, the differences in dynamic characteristics between fine and coarse particles are explored. The normalized autocorrelation length scale, which is the ratio of propagation length of particle velocity fluctuations and particle diameter, is significantly different from fine to coarse particles. One notable feature is that two different flow regimes are found through the radial distribution function. Furthermore, the hydrodynamic stress and collision stress are defined to study the mechanism for the differences between fine and coarse particles. The results imply that the reason for the differences is that the collision effects go beyond the hydrodynamic effects with the increase in the Stokes number.

Simulation of Halon Condensation Processes in Vertical Pipes by the VOF Method

Simulation of Halon Condensation Processes in Vertical Pipes by the VOF Method

An artificial neural network model for the prediction of entrained droplet fraction in annular gas-liquid two-phase flow in vertical pipes

An artificial neural network model for the prediction of entrained droplet fraction in annular gas-liquid two-phase flow in vertical pipes

Conveying characteristics of shrimp feed pellets in pneumatic conveying system and minimum power consumption dissipation factor

Based on the CFD-DEM coupling method, this paper explores the dilute phase pneumatic conveying characteristics of shrimp feed particles. Furthermore, an experimental platform is established to verify the accuracy of the model. The simulated pipeline structure consists of a long horizontal pipe with horizontal bends and long vertical pipe with vertical bends. The results demonstrate a non-linear relationship between the pressure drop of the vertical pipeline and the inlet wind speed. Initially, the pressure drop decreases as the inlet wind speed increases, but it eventually starts to increase. When the inlet wind speed is not less than 18 m/s, the pressure drop of the horizontal pipeline increases with an accelerated inlet wind speed. The optimal inlet wind speed for adult shrimp farming is 24 m/s, while that for juvenile shrimp farming is 21 m/s. A correlation between system energy consumption and solid-gas ratio has been constructed. The ideal solid-gas ratio for adult shrimp farming is 3.69, while that for juvenile shrimp farming is 1.9–2.75. The solid-gas ratio and particle distribution at the inlet section of the straight pipe have a significant impact on the pressure drop characteristics. Their variation with the conveying wind speed directly influences the pressure drop patterns observed in the initial section of the straight pipe. This paper’s findings offer valuable scientific and practical insights for the dilute phase pneumatic conveying of shrimp feed particles, providing guidance for effective and efficient processes in this domain.

Development of an efficient numerical model for two-phase flows in air-lift pumps and its application to deep-sea mining

Air-lift pump system has been selected as a potential application to convey the Rare-Earth mud in deep-sea mining processes due to the superior reliability and schematic simplicity. It is a major focus of current research to study the behavior and mechanism of the two-phase flow. Based on the drift flux model and modified Akawa pressure drop equation, mathematical model controlling the numerical simulation of two-phase flow within air-lift pump system is proposed and constructed. Comparison with experimental data concerning steady and unsteady two-phase flows in vertical pipes shows the high precision of the model. Combing with the robustness test results, it can be found that the present model can accurately predict the maximum flow rate of the two-phase flow at the outlet of the gas lift pump, as well as the average gas and liquid flow rates of the two-phase flow at the outlet in both steady and unsteady states. On this basis, several operation laws of the deep-sea mining airlift pump were studied. The relationship between input and output in the mining process is established and the output of the gas lift pump system is predicted. It is found that changing the position of the injected gas, the time for the two-phase flow in the vertical pipe to reach dynamic equilibrium varies equiprimordially. And changing the maximum amount of gas injected, the time required to reach dynamic equilibrium shows a symmetric relationship with the volume fraction after dynamic equilibrium. A series of laws closely related to the prediction of rare earth mud at the outlet of gas-lift pumps in deep-sea mining are investigated to be proposed for subsequent studies.

The influence of different offset modes on the drainage characteristics of a double stack drainage system in a high-rise building

To meet the functional requirements of high-rise buildings, drainage stacks usually employ an offset pipe in the structural transfer floor. At the offset point, the flow direction changes and the air pressure fluctuates, which significantly influences the drainage system capacity and water seal effectiveness. Different offset modes have different degrees of influence on drainage characteristics. To better understand the influence of different offset modes on drainage characteristics, five different test conditions in double stack building drainage systems were established and investigated. DS1 was a standard double-stack drainage system with anti-reflux H-tube joints for every two floor levels. The remaining four systems were developed from DS1 by adopting various offset pipes (or pipe joints) on the fourth floor. DS2 adopted an S-shape offset pipe joint at the offset point. DS3 adopted double S-shape offset pipe joints. DS4 adopted a 1.0-m-long horizontal offset pipe. DS5 adopted a 1.5-m-long horizontal offset pipe. The pressure fluctuations and water seal losses were chosen as the experimental parameters to determine the maximum discharge capacity according to the Standard for Capacity Test of Vertical Pipe of the Domestic Residential Drainage System CJJ/T 245. The experimental results demonstrated that the installation of offset pipes (or pipe joints) contributed to the abrupt positive pressure and severe water seal losses at the position where flow direction shifted. As the length of the offset pipe increased, the positive pressure was more severe, and maximum discharge capacity was minor. The relationships among the maximum discharge rate, pressure fluctuation limits, and water seal losses are discussed. Lastly, a nondimensional analysis was adopted to understand the relationship between water seal losses and pressure limit values under different discharge rates for current test facilities. Practical application: Pipe offset has the potential to influence a drainage system discharge capacity. As the length of the horizontal offset pipe increases, the discharge capacity will decrease. In the actual design, the length of the offset pipe section should be reduced and this study demonstrates that the application of S-shape offset pipe joints is an efficient solution.

Numerical modelling of multiphase flow hydrodynamics by CFD analysis methods in a double-elbow pipeline

Introduction. Prediction of multiphase flow patterns in pipelines of gas and oil industry is a complicated hydrodynamic process. Hydraulics of gas-liquid flows and erosion processes in pipelines with many bends in which gas, water, oil and air move are insufficiently studied. There are known studies of movement in single-phase flow conditions with one elbow, which is insufficient for design of modern pipeline systems. Therefore, there is a need for in-depth analysis of interaction of media in multiphase flow and transported sand particles. In this paper the effects of elbows on multiphase flow hydraulics and erosion of pipe sections are investigated using computational fluid dynamics (CFD) modelling tools for 100 seconds’ of process.
 
 Materials and methods. A liquid volume model (VOF) was used to simulate three-phase flow: air-water with solids in a pipe with two elbows. Turbulence effects have been accounted for with the RNG k–ε model. The model verification methods from previous studies have been used. For the numerical solution, the Ansys Fluent version 20.1 software package has been used. The results of CFD modelling of the volumetric gas content have shown a good agreement with the available experimental data.
 
 Results. The results showed that the change in the flow regime remains unchanged before the first elbow and after the se-cond elbow in the cork flow. However, for the initial churn flow regime, the flow regime varies at different segments of the flow area before and after each elbow.
 
 Conclusions. The preliminary churn flow in the upper vertical section was transformed to wavy stratified flow in the horizontal section between the two elbows and wavy annular flow in the vertical pipe after the second elbow. The flow pattern in slug flow maintained same after the first elbow, but the Taylor bubbles are lengthier in the horizontal section between the first and second elbows.

Analysis of hydrodynamic forces on freestanding risers with buoyancy cans

Free-standing hybrid risers are vertical slender steel pipes that are commonly used in the oil and gas industry. These slender structures are subjected to complex hydrodynamic loads that results in fatigue damage. The tidal forces that develop on Freestanding Risers (FSR) with buoyancy cans (BC) because of varying outer pipe dimensions are investigated in this work. The study considered riser diameters of 0.2, 0.3, 0.5 and 0.6 meters as well as buoyancy can diameters ranging from 2, 3, 5 and 6 meters. The Morison equation was used in this study to investigate the wave hydrodynamic forces. Separate assessments of the lift force are also carried out consider a water depth (d) of 30 m. The findings reveal that the pipe diameter, wave heights and the wave periods have significant impacts on the hydrodynamic forces on the riser.

UNIVERSAL HYDROGAS-DYNAMIC PATTERNS OF THE DRAINAGE ZONE OF OIL AND GAS WELLS

Large-scale experimental hydrogasodynamic studies of the flow of a two-phase gas-liquid mixture in a vertical pipeline were carried out. Based on the analysis of the results of these experimental studies, it was found that among the results obtained there are dependencies with theoretical bases by which theoretical hydrogasodynamic methods for studying multiphase flow in a vertical pipeline can be developed. The article provides a theoretical hydrogasodynamic study using dependencies describing a two-phase flow in a vertical pipeline of a round section, and it is confirmed by existing experiments. As a result of the gas-hydrodynamic study of pumping wells, in order to confirm the rational use of formation gas energy, a positive effect due to an increase in oil production rate and well process parameters, a relationship was established between well Q production rate, bottom-hole pressure of well P and production of formation gas V. Parameters can be modeled using three-term polynomials. During operation of wells in three modes (Qi, Vi or ∆Pi,Vi, where i = 1,2,3), processing of data obtained as a result of studies, indicators determined by existing research methods were obtained, and the technological mode ensuring layer-bylayer cooperation of the well system was selected.
 It is known that the motion of a two-phase flow of gas-liquid mixtures in a vertical pipe string is described on the basis of energy balance theory. The hydrogasodynamic characteristics of the drainage zone can be obtained in a real oil and gas well, as an experimental installation in the form of

Preparation of modified fly ash-based, core–shell inhibitor and its effect on suppression of Al-Mg alloy dust explosion

Dust explosions caused by energetic metals pose a significant risk to process industries, making it crucial to develop high-performance explosion inhibitors. In this study, the modified power plant solid waste fly ash (FA) was confirmed as a raw material for the preparation of core–shell inhibitors to efficiently suppress dust explosion of Al-Mg alloy. The interfacial compatibility of FA was dramatically improved by using alkali hydrothermal modification and organic modification. It formed a well-coated nano-Mg(OH)2 cladding layer on the surface of modified FA by the heterogeneous nucleation method. In a vertical combustion pipe and a 20 L spherical explosion device, the suppression effect of this novel core–shell inhibitor (FA-2@Mg(OH)2) was investigated. The experimental results showed that the addition of 60 wt% of FA-2@Mg(OH)2 reduced the maximum flame velocity (Vmax), velocity to the top of the pipe (Vtop), and average pulsation degree (Vap) by 87.9 %, 92.5 %, and 87.7 %, respectively, and the peak flame temperature (Tp) declined to 298 °C. The maximum explosion pressure (Pmax) and the maximum explosion pressure rise rate ((dp/dt)max) were reduced by 86.1 % and 92.9 %, respectively. Combining the analysis results of SEM, EDS, XRD, and TG-DSC, the suppression mechanism of FA-2@Mg(OH)2 was explained in depth, mainly from the heat absorption, coating effect, gas dilution, and radical adsorption. This work not only sheds new light on the design of dust explosion suppression functional materials but also broadens the application of industrial solid waste FA.

A comparison study of the behaviors of single-phase turbulent flow at low to moderate Reynolds numbers through a vertical pipe: 3D counters analysis

The study presented three-dimensional (3D) analysis of water's upward flowing through the vertical pipe under turbulent characteristic considerations. Both numerical constructed and improved the model of 3D for cylindrical coordinates of governing equations for incompressible turbulent flow with the Reynolds Average Navier-Stokes (RANS) model using the improved constants of the (k–ε) type. The present model is then compared with a previous study to give the feasibility of the present single-phase turbulent flow parameters. The pipe length is tested to measure how much it affected the turbulent parameters though one of the expected factors is the turbulent time scale. On the other hand, the model is numerically examined to determine the velocity profile, shear rate, and surface deformation of the water domain. While the pressure distribution, turbulent kinetic energy, and turbulent dissipation rate, these parameters are classified as the mechanic's system factors. The simulation is done with wide software used to simulate industrial is COMSOL 5.4 Multiphysics software. The results obtained increased the velocity of three inlet water velocities used ranging from (0.087, 0.105, and 0.123 m/sec) of upward flow. High fluctuation in the water flow moves along the entire pipe length and it can notice the sensitivity to any change in water properties or mechanical properties. The liquid upward flow in turbulent conditions is suffered from many characteristics such them related to liquid properties and others related to the mechanics of the application through the systems. The interaction between the fluid film (fluid boarded the pipe inner diameter) has been observed by the shear rate and liquid surface deformation

A Modified Model to Predict Liquid Loading in Horizontal Gas Wells

Abstract Liquid loading is inevitable during mature gas-well production, leading the liquids to accumulate at the bottomhole and additional pressure loss. Accurately predicting the liquid-loading initiation is crucial to gas-well production optimization. Significant efforts have been made to model liquid-loading behavior. However, few mechanistic models are capable of easily and accurately tackling the complicated non-uniform liquid-film distribution in the slanted section of horizontal wells. Based on liquid-film inversion, this study developed a simple and comprehensive model to calculate liquid-loading initiation for horizontal gas wells. First, the models for film thickness and critical velocity in the vertical pipe are developed. Then, considering the effect of inclination and velocity difference in liquid-film thickness and liquid-holdup distribution between vertical and inclined pipes, the relationship in vertical and inclined pipes between liquid holdup, liquid-film thickness, and angle correction term is established based on the liquid-holdup correlation for horizontal and inclined pipes described in the empirical model developed by Beggs and Brill, so that the thickness of the film and the corresponding critical velocity at any inclination can be calculated. Finally, the new modified model has been evaluated against both experimental and field-measured data set. In comparison to the Luo et al.’s model, the proposed model has been proven to be simple, accurate, and well-performed in predicting the liquid-accumulation initiation in horizontal wells.

High-rise buildings: A risk factor in the COVID-19 Omicron epidemic period

ObjectivesThis study aimed to investigate possible viral transmission scenarios inside a high-rise building during the Omicron phase of the COVID-19 pandemic. Study designCross-sectional study design. MethodsIn order to determine the pathogenicity of the Omicron variant of SARS-CoV-2, demographic, vaccination and clinical data were collected from COVID-19 positive cases during an outbreak in a high-rise residential building in Shenzhen, China, in early 2022. The pattern of viral transmission inside the building was determined through field investigation and engineering analysis. The results highlight the risk of Omicron infection in high-rise residential buildings. ResultsSymptoms of infection with the Omicron variant are predominantly mild. Younger age has a greater impact on the severity of disease than vaccination status. Each floor of the high-rise building investigated contained 7 apartments, numbered 01 to 07, positioned in the same layout on each floor. The drainage system included vertical pipes from the ground to the roof of the building. There were statistically significant differences in infection rates at different time points and incidence ratios between apartment numbers ending in 07 (type 07) and other apartments (P < 0.001). Households with early disease onset were concentrated in apartment type 07 and the severity of their disease was more severe. The incubation period of the outbreak was 5.21–5.31 days and the time-dependent reproduction number (Rt) was 12.08 (95% confidence interval [CI] 7.66, 18.29). Results suggest both non-contact and contact viral transmission may have contributed to the outbreak. The drainage system in the building allows aerosol regurgitation, thus indicating that the structure of the building may have led to spread of the virus from the sewage pipes. Infections in other apartments may have been as result of viral transmission in the elevators and intimate family contact. ConclusionsResults from this study suggest that Omicron transmission was likely to be via the sewage system, supplemented by contact transmission in the stairs and elevators. The environmental spread of Omicron needs to be highlighted and prevented.