scholarly journals MODELING COMPUTATIONAL FLUID DYNAMICS OF MULTIPHASE FLOWS IN ELBOW AND T-JUNCTION OF THE MAIN GAS PIPELINE

Transport ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Yaroslav Doroshenko ◽  
Julia Doroshenko ◽  
Vasyl Zapukhliak ◽  
Lyubomyr Poberezhny ◽  
Pavlo Maruschak
Keyword(s):  
Natural Gas ◽  
Multiphase Flows ◽  
Linear Part ◽  
Erosive Wear ◽  
Gas Pipeline ◽  
Solid Particles ◽  
Ansys Fluent ◽  
Gas Main ◽  
Discrete Phase ◽  
Main Gas Pipeline

The research was performed in order to obtain the physical picture of the movement of condensed droplets and solid particles in the flow of natural gas in elbows and T-junctions of the linear part of the main gas pipeline. 3D modeling of the elbow and T-junction was performed in the linear part of the gas main, in particular, in places where a complex movement of multiphase flows occurs and changes its direction. In these places also occur swirls, collisions of discrete phases in the pipeline wall, and erosive wear of the pipe wall. Based on Lagrangian approach (Discrete Phase Model – DPM), methods of computer modeling were developed to simulate multiphase flow movement in the elbow and T-junction of the linear part of the gas main using software package ANSYS Fluent R17.0 Academic. The mathematical model is based on solving the Navier–Stokes equations, and the equations of continuity and discrete phase movement closed with Launder–Sharma (k–e) two-parameter turbulence model with appropriate initial and boundary conditions. In T-junction, we simulated gas movement in the run-pipe, and the passage of the part of flow into the branch. The simulation results were visualized in postprocessor ANSYS Fluent R17.0 Academic and ANSYS CFD-Post R17.0 Academic by building trajectories of the motion of condensed droplets and solid particles in the elbow and T-junction of the linear part of the gas main in the flow of natural gas. The trajectories were painted in colors that match the velocity and diameter of droplets and particles according to the scale of values. After studying the trajectories of discrete phases, the locations of their heavy collision with the pipeline walls were found, as well as the places of turbulence of condensed droplets and solid particles. The velocity of liquid and solid particles was determined, and the impact angles, diameters of condensed droplets and solid particles in the place of collision were found. Such results provide possibilities for a full and comprehensive investigation of erosive wear of the elbow and T-junction of the linear part of the gas main and adjacent sections of the pipeline, and for the assessment of their strength and residual life.

scholarly journals Improving the efficiency of gas pipeline cleaning by controlling the speed of the gas cleaning

2020 ◽  
pp. 29-35
Author(s):  
V. Ya Grudz ◽  
N. B. Slobodian
Keyword(s):  
High Speed ◽  
Moving Boundary ◽  
Linear Part ◽  
Initial Pressure ◽  
Gas Pipeline ◽  
Technological Scheme ◽  
Gas Pipelines ◽  
Technological Parameters ◽  
Degree Of Reduction ◽  
Main Gas Pipeline

An important aspect of improving the hydraulic efficiency of pipeline transport is its periodic cleaning with mechanical cleaning devices. Cleaning gas pipelines with cleaning pistons is a technologically complex process. It is advisable to adjust the speed of the piston to increase the efficiency of cleaning the pipeline with the crossed track profile. On the ascending and plain sections of the route, maintain a high speed of movement of the device, and on the descending it to reduce. To slow down the movement of the piston in the downstream sections of the main gas pipelines, it is proposed to change the technological scheme of the linear part. It is suggested to use a looping connection to change the flow chart. The change of the speed of movement of the treatment device when changing the technological scheme of the main gas pipeline was evaluated. The influence on the dynamics of the movement of the cleaning piston of the main parameters of the pipeline and looping, as well as the parameters of the movement of the piston itself, are investigated. A mathematical model of the process is built, on the basis of the implementation of which the regularities of the treatment device movement when changing the technological scheme of the gas pipeline are established. An equation was obtained to find the ratio of the mass flow rates of gas in the main gas pipeline before and after connecting the loop, which can be solved by the iteration method. The algorithm is developed and the program of calculation of the degree of reduction of the speed of movement of the piston is developed, depending on the kind of technological parameters and technical characteristics of the treatment device and the pipeline. Based on the calculations, the graphical dependences of the relative speed of the piston on the technological parameters and technical characteristics of the main pipeline were constructed. The authors found that the greatest effect on the degree of reduction of the speed of the piston has the length of the loop. It has been investigated that a decrease in the initial pressure and an increase in the final pressure, as well as an increase in the pressure drop at the moving boundary, lead to an improvement in the braking conditions

scholarly journals IMPROVING THE EFFICIENCY OF FUNCTIONING OF REPAIR-OPERATING UNITS IN THE SYSTEM OF MAINTENANCE AND REPAIR OF MAGISTRALS

2019 ◽  
pp. 104-115
Author(s):  
V. Y. Grudz ◽  
V. V. Grudz ◽  
V. M. Bodnar ◽  
M. S. Chernetsky
Keyword(s):  
Linear Part ◽  
Gas Pipeline ◽  
Operating Conditions ◽  
Gas Pipelines ◽  
Maintenance And Repair ◽  
Technological Structure ◽  
Optimal Technology ◽  
Main Gas Pipeline ◽  
Operating Units

The classification of failures and damages of the linear part and its separate elements is carried out, variants of technology of carrying out of preventive and repair-restoration works and modular-technological structure of repair and maintenance units are formulated. Particular attention is paid to improving the efficiency of the operation of a separate repair and maintenance unit during maintenance and repair with a known layout scheme and a certain mode of control and restoration works by choosing the optimal technology of work and rational equipment of units and crews leaving for the route. On the basis of the analysis of the technology of work execution it is shown that only a small part of the repair and maintenance measures requires the use of powerful machinery and equipment, which include the first level of priority work on the replacement of gas pipeline sections, work, damage elimination, work on elimination of significant pipeline displacements, work for restoration of soil collapse of the main gas pipeline. In addition, each type of work on the objects of the linear part requires the use of the same vehicles. The type and number of vehicles depend on the particular operating conditions, as well as on the possibility and feasibility of purchasing and operating a particular type of equipment. The method of estimation of indexes of maintenance of linear part of main gas pipelines and efficiency of functioning of repair and maintenance units during maintenance and repair is developed.

Numerical Investigation of the Effect of Solid Particles on Liquid Holdup in Stratified Wavy Gas-Liquid Flow in Natural Gas Pipelines

2014 ◽  
Author(s):  
Mahdi Jafari ◽  
Zohreh Mansoori ◽  
Majid Saffar Avval ◽  
Goodarz Ahmadi
Keyword(s):  
Liquid Phase ◽  
Natural Gas ◽  
Solid Phase ◽  
Gas Pipeline ◽  
Solid Particles ◽  
Liquid Holdup ◽  
Horizontal Pipe ◽  
Natural Gas Pipelines ◽  
Gas Liquid Flow ◽  
Liquid Flows

The effect of presence of solid particles on stratified wavy gas-liquid flows has been studied. The height of liquid phase in the natural gas pipeline is a key parameter in designing and can affect the corrosion/erosion rate. In present paper, the numerical four-way simulation of solid particles in gas-liquid wavy stratified flow has been used. The computational model is shown to be able to evaluate the effect of the particles on liquid holdup which is critical for gas pipeline design. The particles cause the liquid phase height in horizontal pipe decreases by increasing the solid phase concentration.

scholarly journals Improving the methodology for technical assessment of the linear part of main gas pipelines

2019 ◽  
pp. 102-111
Author(s):  
Aleksandr A. Razboynikov ◽  
Nikolay S. Barsukov
Keyword(s):  
Linear Part ◽  
Technical Condition ◽  
Gas Pipeline ◽  
Gas Pipelines ◽  
Partial Picture ◽  
Technical Assessment ◽  
Main Gas Pipeline

Today evaluation of the technical assessment of the linear part of main gas pipeline is one of the most important tasks of pipeline operation. However, many assessment methodologies provide only a partial picture of the technical condition and don’t take into account the conditions for pipeline laying. This article discusses the improvement of methods for technical assessment of main gas pipelines.

Method of natural gas evacuation from subject to repair area of main gas pipeline

2018 ◽  
pp. 143-157
Author(s):  
T.V. Bunko ◽  
◽  
V.V. Safonov ◽  
Z.N. Matsuk ◽  
◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Pipeline ◽  
Main Gas Pipeline

scholarly journals REGULATORY PROVISION OF SAFETY OF GAS TRANSPORT. CONSTRUKTIONAL DESIGN OF MOBILE COMPRESSOR STATIONS

2021 ◽  
pp. 13-19
Author(s):  
V. BIELIKOV ◽  
Z. MATSUK
Keyword(s):  
Natural Gas ◽  
Gas Pressure ◽  
Gas Pipeline ◽  
Industrial Safety ◽  
Technical Requirements ◽  
The World ◽  
Transportation Process ◽  
Mobile Compressor ◽  
Main Gas Pipeline ◽  
Gas Supply

Problem statement. The basis for the safety and efficiency of the main gas transportation in the world is the tightness of the gas transportation system. A component of the level of industrial safety and efficiency of gas transmission enterprises is the emissions of natural gas into the working area, the environment and the associated costs. Numerous methods of repairing pipeline gas transportation facilities, such as enhancing the bearing capacity of pipelines, repairing defects under gas pressure without interrupting the transportation process, etc., are either not devoid of risks from the point of view of industrial safety, or are energy and resource inefficient. The main type of repair that restores the operable state of the gas transmission system is the replacement of defective equipment, but it is still associated with the release of large volumes of natural gas into the environment. In the second decade of the 2000s, thanks to the rapid development of compressor technology and the invention of a sufficient number of ways to connect compressor units (stations) to main gas pipelines, without stopping the gas transportation process, gas transmission enterprises of the world had a real opportunity to evacuate gas from pipeline sections subject to repair (maintenance ) or accumulate it (control gas pressure in local areas), but the analysis of world experience in the development of gas pressure control technology in localized sections of gas pipelines allows us to assert that there are certain disparities between them in terms of operational safety and the complete absence of regulatory support for the transportation process in Ukraine gas using mobile compressor stations. With this approach to the production process, it is difficult to improve the safety and efficiency of the gas transportation process. The potential for reducing natural gas emissions from the world's gas industry reaches billions of cubic meters of natural gas per year. Purpose of the article. Development of technical requirements for mobile compressor units (stations), which will make it possible to design domestic gas compressor units (stations) capable of safely performing work on pumping natural gas from a localized section of the main gas pipeline to an existing main gas pipeline, within no more than 96 hours, without restrictions on gas supply to consumers. Conclusion. The technical requirements developed by us for mobile compressor units (stations) allow us to design domestic compressor units (stations) capable of safely performing work on pumping natural gas from a localized section of the main gas pipeline to the existing main gas pipeline, within no more than 96 hours, without restrictions on gas supply to consumers.

scholarly journals Regularities of safe control of piston compressor units of mobile compressor stations

2021 ◽  
pp. 76-81
Author(s):  
Z.N Matsuk ◽  
T.V Bunko ◽  
A.S Belikov ◽  
V.A Shalomov
Keyword(s):  
Natural Gas ◽  
Gas Pressure ◽  
Gas Pipeline ◽  
Relative Mass ◽  
Time Interval ◽  
Relative Pressure ◽  
Gas Pipelines ◽  
Mobile Compressor ◽  
Gas Pumping ◽  
Main Gas Pipeline

Purpose. Ensuring the optimal mode of gas transportation from local sections of the main gas trunkline (GT), subject to repair (maintenance) and/or shutdown, to existing main gas trunkline based on the calculation, determination, and establishment of rational values of the operating modes of mobile compressor stations during the entire time of gas pumping. Methodology. The studies are based on existing physical principles and laws that describe the effect of the properties of natural gas and the geometric parameters of pipelines through which gas is pumped on the dynamics of changes in the mass and pressure of the transported gas. The calculation of the change in the mass and pressure of the gas in the gas pipeline from which the gas is pumped is based on a number of existing theoretical and empirical dependencies included in the generally accepted methods for their calculation. Known physical relationships and mathematical models are used to carry out the calculations. Findings. The mass approach to the issue of calculating the gas transportation time is more mathematically accurate than the volumetric one. The ratio of the relative mass to the relative gas pressure in a localized section of the main gas pipeline, during the entire pumping time, is a constant value. The use of the values of the quantities obtained at the point of intersection of the graphs of changes in the relative mass and relative pressure of the gas, in the preliminary calculation of the time for pumping gas, or pressure, or mass, or the volume of gas in each time interval, makes it possible to select the optimal rate of building up/reducing gas pressure by compressor units and optimal modes of gas transportation by operating gas pipelines during the operation of mobile compressor stations. Originality. The proposed approach to calculating and determining the time of gas pumping by mobile compressor stations from local sections of the main gas pipelines subject to repair (maintenance) and/or shutdown to sections of existing main gas pipelines proves that it is advisable to establish stable patterns in the transportation of natural gas using reciprocating compressor units only after modeling in time the change in the mass and pressure of gas in the local section of the main gas pipeline from which the gas is pumped. Practical value. The proposed approach to optimizing the time of gas pumping by mobile compressor stations makes it possible to increase the level of energy and resource efficiency of gas transmission enterprises, as well as to improve the technical and economic indicators of technologies for repairing the main gas pipelines, compressor stations of main gas pipelines associated with the need to bleed gas from sections of the main (technological) pipelines subject to repair (maintenance) and/or shutdown. Optimization of gas pumping time significantly reduces the time spent by employees of gas transmission enterprises under the influence of hazardous and harmful production factors, thereby reducing the level of relevant risks. Gas emissions and associated risks are reduced by 90%.

scholarly journals CFD-based numerical simulation of cyclone separator for separating stigmas from petals of saffron

2020 ◽  
Author(s):  
Javad Nemati ◽  
Babak Beheshti ◽  
Ali Mohammad Borghei
Keyword(s):  
Separation Efficiency ◽  
Solid Phase ◽  
Equations Of Motion ◽  
Fluid Phase ◽  
Reynolds Stress Model ◽  
Continuous Phase ◽  
Solid Particles ◽  
Inlet Section ◽  
Ansys Fluent ◽  
Discrete Phase

This study numerically modeled the flow of a fluid (air) and solid particles (saffron flower) inside a cyclone using the finite volume method (FVM) in ANSYS Fluent. The continuous phase was simulated under steady state conditions, as the initial condition, using the Reynolds Stress Model (RSM) for turbulence at three constant inlet air velocities of 1.5 m/s, 2.5 m/s, and 3.5 m/s over the inlet section. One-way coupling was assumed to govern all numerical analyses. The fluid phase and particles were treated as the continuous medium (within a Eulerian framework) and discrete phase (within a Lagrangian framework), respectively. The equations governing the gas phase included the compressible Navier–Stokes and the conservation of mass. The discrete phase equations included the equations of motion for three different particles including petals, stigmas, and anthers. According to the numerical results, the cyclone separation efficiency was calculated, and the static pressure and velocity contours were plotted. The results showed the capability of the CFD-based simulation for an accurate demonstration of the behavior of the fluid–solid phase. Accordingly, it can be used to predict the efficiency of stigma separation from petals of saffron using airflow in the cyclone. According to the results, the highest cyclonic separation efficiency of 89% was achieved at an inlet air velocity of 3.5 m/s, which was very close to the experimental data.

Study of the mechanical properties of the gas pipeline metal after long-term operation in conditions of the North

2020 ◽  
Vol 86 (6) ◽  
pp. 48-54
Author(s):  
N. I. Golikov ◽  
M. M. Sidorov ◽  
I. I. Sannikov ◽  
A. K. Rodionov
Keyword(s):  
Mechanical Properties ◽  
Residual Strength ◽  
Linear Part ◽  
Full Scale ◽  
Gas Pipeline ◽  
Term Operation ◽  
The North ◽  
Full Scale Tests ◽  
Main Gas Pipeline

The residual strength and technical condition of the material of 530-mm steel pipe (14KhGS) of main gas pipeline are estimated to ensure the safety of long-term operation of pipelines in climatic conditions of the North. The mechanical properties are determined using standard methods of mechanical testing in laboratory conditions. A full-scale pressure test up to failure is used to determine the actual values of the fracture toughness and safety factor of the pipe. Full-scale tests were carried out on a test bench, a computer-measuring complex which displayed the reaction of the object to the load. A pipe fragment was cut from the linear part of the main gas pipeline and welded with spherical plugs. The outer surface of the pipe was notched along the pipe axis. The depth of the notch was calculated such that the breaking load on the ligament section at the notch site corresponded to the working pressure of the gas pipeline. No significant changes in the mechanical properties of the pipe metal were revealed in the absence of visible corrosion and deformation damage during long-term operation of the pipe in the North. Impact tests did not reveal embrittlement of the metal of the tested pipes. Full-scale tests of a pipe with an artificially applied defect made it possible to calculate the value of the critical stress intensity factor, which allowed us to estimate the residual strength of a pipe with a longitudinal crack. The value of the strength criterion of the fracture mechanics indicates the preservation of a sufficiently high viscosity of sheet metal pipes. Similar tests of the pipes (of other size and made of other materials) operating in the main gas pipelines should be continued taking into account temperature ranges and material degradation after long-term operation.

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