scholarly journals Numerical Analysis of the Characteristics of Gas Explosion Process in Natural Gas Compartment of Utility Tunnel Using FLACS

2019 ◽  
Vol 12 (1) ◽  
pp. 153 ◽  
Author(s):  
Zexu Li ◽  
Jiansong Wu ◽  
Mingyu Liu ◽  
Yuntao Li ◽  
Qiuju Ma
Keyword(s):  
Natural Gas ◽  
Gas Explosion ◽  
Rapid Urbanization ◽  
Flame Acceleration ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Urban Safety ◽  
Fire And Explosion ◽  
Utility Tunnel ◽  
Urbanization In China

With the rapid urbanization in China, directly buried municipal pipelines have been gradually replaced by urban utility tunnels due to a serious shortage of urban underground spaces and weak disaster prevention of traditional municipal pipelines. The urban utility tunnels normally contain electricity pipelines, natural gas pipelines, heat pipelines, sewer pipelines, etc. If a natural gas pipeline leaks, a fire and explosion might occur and lead to serious consequences. In this study, the characteristics of gas explosion in a natural gas compartment of urban utility tunnel are investigated based on FLACS (Flame Acceleration Simulator) simulations. The results revealed that the flame profile undergoes two unstable flame stages. When the ignition position is set at the middle area (100.25, 1.2, 1.4 m) of the 200 m-long natural gas compartment, the maximum overpressure of the gas explosion in the 200 m-long natural gas compartment is 25.17 bar, which is the largest maximum overpressure under all gas explosion simulation setups. It is also found that the length of the natural gas compartment and different ignition positions have slight effects on the maximum overpressure. This study could provide technical support for structural strength design and division of the fireproofing area of the natural gas compartment in the utility tunnel, which is of great significance to improve urban safety during sustainable development.

Steady State Performance Simulation of Natural Gas Pipeline Driven by Compressor Stations

2016 ◽  
Author(s):  
S. M. Suleiman ◽  
Y. G. Li
Keyword(s):  
Steady State ◽  
Natural Gas ◽  
Flow Rate ◽  
Operating Conditions ◽  
Simulation Approach ◽  
Gas Pipelines ◽  
Performance Simulation ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Pumping Stations

Natural gas pipeline plays an important role in transporting natural gas over a long distance. Its performance and operating behavior are affected by many factors, such as ambient conditions, natural gas flow rate, operation and control of compressor pumping stations, etc. Better understanding of the performance and behavior of an integrated pipeline-compressor system used for gas transmission will be beneficial to both design and operation of natural gas pipelines. This paper introduces a novel steady-state thermodynamic performance simulation approach for natural gas pipelines based on fundamental thermodynamics with the inclusion of the coupling between a pipeline and compressor pumping stations. A pipeline resistance model, a compressor performance model characterized by an empirical compressor map and a pipeline control schedule for the operation of an integrated pipeline-compressor system are included in the simulation approach. The novel approach presented in this paper allows the analysis of the thermodynamic coupling between compressors and pipes and the off-design performance analysis of the integrated pipeline-compressor system. The introduced simulation approach has been applied to the performance simulation of a typical model pipeline driven by multiple centrifugal compressor pumping stations. It is assumed in the pipeline control schedule that the total pressure at the inlet of compressor stations is kept constant when pipeline operating condition changes. Such pipeline operating conditions include varying ambient temperature and varying natural gas volumetric flow rate. The performance behavior of the pipeline corresponding to the change of operating conditions has been successfully simulated. The introduced pipeline performance simulation approach is generic and can be applied to different pipeline-compressor systems.

scholarly journals Options of Natural Gas Pipeline Reassignment for Hydrogen: Cost Assessment for a Germany Case Study

2019 ◽  
Author(s):  
Simonas Cerniauskas ◽  
Antonio Jose Chavez Junco ◽  
Thomas Grube ◽  
Martin Robinius ◽  
Detlef Stolten
Keyword(s):  
Natural Gas ◽  
Energy System ◽  
Gas Pipeline ◽  
Cost Functions ◽  
Pipeline System ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
System P ◽  
Availability Constraints ◽  
Hydrogen Supply

The uncertain role of the natural gas infrastructure in the decarbonized energy system and the limitations of hydrogen blending raise the question of whether natural gas pipelines can be economically utilized for the transport of hydrogen. To investigate this question, this study derives cost functions for the selected pipeline reassignment methods. By applying geospatial hydrogen supply chain modeling, the technical and economic potential of natural gas pipeline reassignment during a hydrogen market introduction is assessed.The results of this study show a technically viable potential of more than 80% of the analyzed representative German pipeline network. By comparing the derived pipeline cost functions it could be derived that pipeline reassignment can reduce the hydrogen transmission costs by more than 60%. Finally, a countrywide analysis of pipeline availability constraints for the year 2030 shows a cost reduction of the transmission system by 30% in comparison to a newly built hydrogen pipeline system.

scholarly journals Process of Natural Gas Explosion in Linked Vessels with Three Structures Obtained Using Numerical Simulation

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 52 ◽  
Author(s):  
Qiuhong Wang ◽  
Yilin Sun ◽  
Xin Li ◽  
Chi-Min Shu ◽  
Zhirong Wang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Time Pressure ◽  
Combustion Products ◽  
Gas Explosion ◽  
Spherical Vessel ◽  
Flame Acceleration ◽  
Physical Experiments ◽  
Gas Explosions ◽  
Simulation Results

Combinations of spherical vessels and pipes are frequently employed in industries. Scholars have primarily studied gas explosions in closed vessels and pipes. However, knowledge of combined spherical vessel and pipe systems is limited. Therefore, a flame acceleration simulator was implemented with computational fluid dynamics software and was employed to conduct natural gas explosions in three structures, including a single spherical vessel, a single spherical vessel with a pipe connected to it, and a big spherical vessel connected to a small spherical vessel with a pipe. These simulations reflected physical experiments conducted by at Nanjing Tech University. By changing the sizes of vessels, lengths of pipes, and ignition positions in linked vessels, we obtained relevant laws for the time, pressure, temperature, and concentrations of combustion products. Moreover, the processes of natural gas explosions in different structures were obtained from simulation results. Simulation results agreed strongly with corresponding experimental data, validating the reliability of simulation.

Reliability Calculation Method for Natural Gas Pipelines with Girth Weld Defects Identified through In-Line Inspection

2019 ◽  
Vol 795 ◽  
pp. 225-232 ◽  
Author(s):  
Ming Fei Li ◽  
Jian Chen ◽  
Zheng Qiang Lei ◽  
Hong Long Zheng ◽  
Zai Rong Li
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Plastic Material ◽  
Pipeline System ◽  
Long Distance ◽  
Weld Defects ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
The Monte Carlo Method ◽  
Reliability Assessments

To introduce a method for reliability analysis of China's large-scale natural gas pipeline system, one should first have a method to calculate the reliability of pipe segments, compressors, valves, and other factors. This article models the rules prescribed in BS7910-2013, a guide to methods for assessing the acceptability of flaws in metallic structures, and combines pipeline reliability assessments from CSA Z662-2015 to present a method (based on the Monte Carlo method) to calculate the failure probability/reliability of long-distance pipelines containing a large number of girth weld defects. The method involves the destruction of plastic material, brittle fracture failure analysis, consideration of the division of units by using pipeline area classes for calculation, and reliability index analysis. The results of a magnetic flux leakage (MFL) in-line inspection (ILI) of a defective girth weld from a section of a pipeline in China are used to demonstrate how to determine the reliability of the entire pipeline.

The Reliability-Based Assessment of an In-Service X80 Natural Gas Pipeline in China

2014 ◽  
Author(s):  
Kai Wen ◽  
Jing Gong ◽  
Boyuan Zhao ◽  
Wenwei Zhang ◽  
Zhenyong Zhang
Keyword(s):  
Monte Carlo ◽  
Natural Gas ◽  
Reliability Analysis ◽  
Limit State ◽  
Gas Pipeline ◽  
Industrial Practice ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
State Models ◽  
Basic Input

Guidelines for the application of reliability-based design and assessment to natural gas pipelines were developed under PRCI sponsorship in 2005. The methodology underlying these guidelines has since been adopted as a non-mandatory Annex in the CSA Z662 standard (Annex O). Following the code in CSA Z662 Annex O, the reliability analysis of an in-service X80 pipeline in North-West China is performed using Monte Carlo technique. In this paper, the distributions of basic input parameters such as loadings, material property is derived based on the data collected from industrial practice. And the analysis of limit states, such as yielding of the defect-free pipeline, bursting of the defect-free pipeline, local buckling due to restrained thermal expansion and excessive plastic deformation, is proceeded based on these distributions. The core of reliability analysis lies in the selection and correction of limit state functions. The modification and extension of limit state models is very significant to accurately calculate probability of failure of different natural gas pipelines, so the limit state models are refined to adapt to the specific work conditions in China. A Monte Carlo reliability analysis framework capable of incorporating the data of industrial practice and limit state models has been developed and applied to the evaluation of the X80 natural gas pipeline, then a practical approximation is developed by using Monte Carlo simulation results. A practical example of an in-service X80 natural gas pipeline is presented to illustrate the availability of the reliability analysis. Furthermore, results generated by different basic input parameters in a limit state function are compared. The sensitivity analysis shows the degree of influence of various basic parameters.

Multi-Factor and Polymorphism Failure Probability Calculation for Natural Gas Pipelines

2013 ◽  
Vol 401-403 ◽  
pp. 2170-2174 ◽  
Author(s):  
Ya Ping Yang ◽  
Yong Mei Hao ◽  
Zhi Xiang Xing
Keyword(s):  
Natural Gas ◽  
Bayesian Network ◽  
Calculation Model ◽  
Gas Pipelines ◽  
Single Factor ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Quantitative Calculation ◽  
Failure State ◽  
Probability Calculation

A Bayesian network quantitative calculation model for urban natural gas pipelines was established by using the unique logic of a Bayesian network in handling complicated risk systems. By using a natural gas pipeline as an example, failure situations such as single factor polymorphism, double factor polymorphism, and multi-factor polymorphism of a pipeline were quantitatively calculated to obtain the probability of top events and the structural importance of basic factors. The proposed method not only reflects clearly the effects of different factors but also predicts the failure state of urban natural gas pipelines comprehensively and accurately. The results of the proposed method can serve as a significant reference for the risk management and fault processing of city natural gas pipelines.

scholarly journals An Investigation into the Volumetric Flow Rate Requirement of Hydrogen Transportation in Existing Natural Gas Pipelines and Its Safety Implications

Gases ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 156-179
Author(s):  
Abubakar Jibrin Abbas ◽  
Hossein Hassani ◽  
Martin Burby ◽  
Idoko Job John
Keyword(s):  
Natural Gas ◽  
Flow Rate ◽  
Compressibility Factor ◽  
Volumetric Flow Rate ◽  
Gas Pipeline ◽  
Internal Erosion ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Wide Range

As an alternative to the construction of new infrastructure, repurposing existing natural gas pipelines for hydrogen transportation has been identified as a low-cost strategy for substituting natural gas with hydrogen in the wake of the energy transition. In line with that, a 342 km, 36″ natural gas pipeline was used in this study to simulate some technical implications of delivering the same amount of energy with different blends of natural gas and hydrogen, and with 100% hydrogen. Preliminary findings from the study confirmed that a three-fold increase in volumetric flow rate would be required of hydrogen to deliver an equivalent amount of energy as natural gas. The effects of flowing hydrogen at this rate in an existing natural gas pipeline on two flow parameters (the compressibility factor and the velocity gradient) which are crucial to the safety of the pipeline were investigated. The compressibility factor behaviour revealed the presence of a wide range of values as the proportions of hydrogen and natural gas in the blends changed, signifying disparate flow behaviours and consequent varying flow challenges. The velocity profiles showed that hydrogen can be transported in natural gas pipelines via blending with natural gas by up to 40% of hydrogen in the blend without exceeding the erosional velocity limits of the pipeline. However, when the proportion of hydrogen reached 60%, the erosional velocity limit was reached at 290 km, so that beyond this distance, the pipeline would be subject to internal erosion. The use of compressor stations was shown to be effective in remedying this challenge. This study provides more insights into the volumetric and safety considerations of adopting existing natural gas pipelines for the transportation of hydrogen and blends of hydrogen and natural gas.

scholarly journals Analysis of Stresses on Buried Natural Gas Pipeline Subjected to Ground Subsidence

1998 ◽  
Author(s):  
Hyoung-Sik Kim ◽  
Woo-Sik Kim ◽  
In-Wan Bang ◽  
Kyu Hwan Oh
Keyword(s):  
Natural Gas ◽  
Gas Pipeline ◽  
Ground Subsidence ◽  
Safety Criterion ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Main Pipelines ◽  
Stress And Deformation ◽  
Buried Gas Pipeline ◽  
Allowable Settlement

This study was initiated to examine the stress and deformation characteristics of the pipelines which were subjected to various environmental conditions in order to confirm their integrity. As the part of them, this paper presents the analysis results for the effect of ground subsidence combined with main loads on buried natural gas pipelines. The ground subsidence which can occur for buried gas pipeline has been classified to the three cases. Finite element method was used to analyze the effect of ground subsidence on pipeline of 26 inch (0.660 m) and 30 inch (0.762 m) diameter used as high pressure (70 Kgf/cm2(686.4 Pascal)) main pipelines. This paper shows the result of stress analysis for the pipelines subjected to those three case ground subsidence. Comparing these results with safety criterion of KOGAS (0.9 σ y), maximum allowable settlement and loads have been calculated.

scholarly journals Analysis of a model of a natural gas pipeline—a transfer function approach

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Luke Baker ◽  
Dieter Armbruster ◽  
Anna Scaglione ◽  
Rodrigo B Platte
Keyword(s):  
Steady State ◽  
Natural Gas ◽  
Transmission Lines ◽  
Electrical Circuit ◽  
Gas Pipelines ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Linear Partial Differential Equations ◽  
Electric Transmission Lines ◽  
Dependent Flow

Abstract A framework for natural gas pipelines is developed in a context similar to the theory of electric transmission lines. The system of semi-linear partial differential equations describing the time-dependent flow of natural gas is linearized around the steady-state flow. Additional approximations lead to a constant coefficient linear system that is equivalent to an electrical circuit that is analytically solvable and admits an ABCD matrix representation of input and output. The sinusoidal steady-state operation of natural gas pipelines is analysed including the distortion of waves. It is shown that the timing of the propagation of phases and other events is accurately represented in the approximation. The quantitative accuracy for flux and gas density of the approximation depending on different operating scenarios and depending on the frequency of the disturbances is documented.

Numerical Simulation of Hydrate Transport in Natural Gas Pipeline

1998 ◽  
Vol 120 (1) ◽  
pp. 20-26 ◽  
Author(s):  
S. O. Ibraheem ◽  
M. A. Adewumi ◽  
J. L. Savidge
Keyword(s):  
Natural Gas ◽  
Fluid Model ◽  
Hydrate Formation ◽  
Higher Order ◽  
Solid Particles ◽  
Natural Gas Pipelines ◽  
Natural Gas Pipeline ◽  
Offshore Production ◽  
Two Fluid Model ◽  
Viable Approach

Accurate modeling of hydrate transportation in natural gas pipelines is becoming increasingly important in the design and operation of offshore production facilities. The dynamics involved in the formation of hydrate particles and in its transportation are governed by the multiphase hydrodynamics equations ensuing from the balance of mass, momentum, and energy. In this study, a two-fluid model is solved to characterize particulate transportation. The numerical algorithm employed is stable and robust and it is based on higher-order schemes. This is necessary since the governing equations describing the simultaneous flow of gas and solid particles are hyperbolic and, thus, admit discontinuities. Specialized higher-order schemes provide a viable approach for efficient frontal tracking of continuity waves in particular. Several simulation experiments that can facilitate thorough understanding of the design and maintenance of pipelines susceptible to hydrate formation are presented.

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