Interaction of fluid dynamic factors in the migration and accumulation of natural gas

2002 ◽  
Vol 47 (14) ◽  
pp. 1207-1211 ◽  
Author(s):  
Yan Song ◽  
Xinyu Xia ◽  
Zhenliang Wang ◽  
Yi Wang ◽  
Shengbiao Hu
Keyword(s):  
Natural Gas ◽  
Fluid Dynamic ◽  
Dynamic Factors

scholarly journals Assessment of Cascading Accidents of Frostbite, Fire, and Explosion Caused by Liquefied Natural Gas Leakage

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Chengjun Yue ◽  
Li Chen ◽  
Hengbo Xiang ◽  
Linfeng Xu ◽  
Shigang Yang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Natural Gas ◽  
Fluid Dynamic ◽  
Liquefied Natural Gas ◽  
Toxic Substances ◽  
Origin And Evolution ◽  
Gas Leakage ◽  
Wind Speeds ◽  
Vapor Cloud ◽  
Computational Fluid Dynamic Software

Liquefied natural gas (LNG) leaks often lead to cascading accident disasters, including vapor cloud release, explosion, fire, and toxic gas release. The origin and evolution of each accidental disaster must be considered when assessing safety. This paper discusses the safety assessment project of an LNG gas storage station in Xuzhou, China. Multiple conceivable disasters due to the leakage of LNG storage tanks are simulated and analyzed using the computational fluid dynamic software FLACS. We studied different wind speeds interacting with the flammable vapor cloud area and creating frostbite in areas of low temperature. Diffusion simulations of vapor cloud explosion (VCE), thermal radiation, and the distribution of toxic substances were performed. The overpressure-impulse criterion was used to calculate the influence range of VCE. Heat flux, heat dose, and heat flux-heat dose criteria were used to calculate the safe distance for personnel in the event of fire. Based on the calculation results of the three latter criteria, this paper recommends using the heat flux criterion to evaluate fire accidents. The danger zone of each accident was compared. VCE accidents yielded the largest area.

Fluid dynamic factors in tracheal pressure measurement

1981 ◽  
Vol 51 (1) ◽  
pp. 218-225 ◽  
Author(s):  
H. K. Chang ◽  
J. P. Mortola
Keyword(s):  
Endotracheal Tube ◽  
Pressure Measurement ◽  
Fluid Dynamic ◽  
Theoretical Explanation ◽  
Apparent Paradox ◽  
Cross Sectional ◽  
Tracheal Cannula ◽  
Dynamic Factors ◽  
Tracheal Pressure

Because tracheal pressure measurement generally involves the use of a cannula or an endotracheal tube, fluid dynamic factors may cause a considerable artifact. We present a theoretical explanation of the observed apparent paradox in which the resistance of a tracheal cannula or an endotracheal tube is isolation was found to exceed the resistance of the airways plus the cannula or the tube in situ. By estimating the viscous dissipation and the kinetic energy change in a conduit with sudden variation of cross-sectional area, a predictive model is derived. The predictions are verified by a series of in vitro experiments with both steady and oscillatory flows. The experiments showed that the pressure recorded from the sidearm of a tracheal cannula or endotracheal tube contains an error which, in general, increased with the mean Reynolds' number of the through flow and also depends on the diameter ratio between the trachea and the tube or cannula, the position of the pressure tap, and the frequency of ventilation. When feasible, direct measurement with a needle in the trachea is suggested as a way to avoid the possible artifacts arising from the use fo a side tap of the cannula. Theoretical considerations, as well as in vitro and animal experiments, indicate that adding a properly chosen expansion to the tracheal cannula makes it possible to alter inspiratory and expiratory pressures selectively. This device may prove useful in control of breathing studies.

Hydrogen Combustion Within a Gas Turbine Reheat Combustor

2012 ◽  
Author(s):  
Madhavan Poyyapakkam ◽  
John Wood ◽  
Steven Mayers ◽  
Andrea Ciani ◽  
Felix Guethe ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Natural Gas ◽  
Gas Turbine ◽  
Dynamic Properties ◽  
Fluid Dynamic ◽  
Fold Increase ◽  
Inlet Temperature ◽  
Turbine Performance ◽  
Auto Ignition ◽  
Operating Window

This paper describes a novel lean premixed reheat burner technology suitable for Hydrogen-rich fuels. The inlet temperature for such a combustor is very high and reaction of the fuel/oxidant mixture is initiated through auto-ignition, the delay time for which reduces significantly for Hydrogen-rich fuels in comparison to natural gases. Therefore the residence time available for premixing within the burner is reduced. The new reheat burner concept has been optimized to allow rapid fuel/oxidant mixing, to have a high flashback margin and to limit the pressure drop penalty. The performance of the burner is described, initially in terms of its fluid dynamic properties and then its combustion characteristics. The latter are based upon full-scale high-pressure tests, where results are shown for two variants of the concept, one with a pressure drop comparable to today’s natural gas burners, and the other with a two-fold increase in pressure drop. Both burners indicated that Low NOx emissions, comparable to today’s natural gas burners, were feasible at reheat engine conditions (ca. 20 Bars and ca. 1000C inlet temperature). The higher pressure drop variant allowed a wider operating window. However the achievement of the lower pressure drop burner shows that the targeted Hydrogen-rich fuel (70/30 H2/N2 by volume) can be used within a reheat combustor without any penalty on gas turbine performance.

Autoignition of Hydrogen / Natural Gas / Nitrogen Fuel Mixtures at Reheat Combustor Operating Conditions

2012 ◽  
Author(s):  
Julia Fleck ◽  
Peter Griebel ◽  
Manfred Aigner ◽  
Adam M. Steinberg
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Volume Fraction ◽  
Fluid Dynamic ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Mixing Zone ◽  
Fuel Injector ◽  
Jet Penetration ◽  
Penetration Depths

Previous autoignition studies at conditions relevant to reheat combustor operation have indicated that the presence of relatively small amounts of natural gas (NG) in H2/N2 fuel significantly changes the autoignition behavior. The present study further elucidates the influence of NG on autoignition, kernel propagation, and subsequent flame stabilization at conditions that are relevant for the practical operation of gas turbine reheat combustors (p = 15 bar, Tinlet > 1000 K, hot flue gas, appropriate residence times). The experimental investigation was carried out in a generic, optically accessible reheat combustor. Autoignition events in the mixing zone were recorded by a high-speed camera at frame rates of up to 30,000 fps. This paper describes the autoignition behavior as the H2 volume fraction is increased (decreasing NG) in a H2/NG/N2 fuel mixture for two different jet penetration depths. Additionally, the subsequent flame stabilization phenomena and the structure of the stabilized flame are discussed. The results reveal that autoignition kernels occurred even for the lowest H2 fuel fraction, but they did not initiate a stable flame in the mixing zone. Increasing the H2 volume fraction decreased the distance between the initial position of the autoignition kernels and the fuel injector, finally leading to flame stabilization. The occurrence of autoignition kernels at lower H2 volume fractions (H2/(H2+NG) < 85%) was not found to be significantly influenced by the fluid dynamic and mixing field differences related to the different jet penetration depths. In contrast, autoignition leading to flame stabilization was found to depend on jet penetration; flame stabilization occurred at lower H2 fractions for the higher jet penetration depth (H2/(H2+NG) ≈ 89 compared to H2/(H2+NG) ≈ 95 vol. %).

Design and Performance of High-Pressure Blowoff Silencers

1971 ◽  
Vol 93 (2) ◽  
pp. 695-702 ◽  
Author(s):  
Cecil R. Sparks ◽  
D. E. Lindgren
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Field Data ◽  
Fluid Dynamic ◽  
Gas Pipeline ◽  
Noise Generation ◽  
Test Results ◽  
Natural Gas Pipeline ◽  
And Performance

Through the application of fluid dynamic and acoustic theory, the noise generation of a high pressure blowoff can be approximated. The effects of silencer configurations can likewise be predicted through the application of pertinent field data taken to define performance of the silencer components. This paper describes recent test results and their application to improved silencer design for natural gas pipeline applications.

Evaluation of “Marching Algorithms” in the Analysis of Multiphase Flow in Natural Gas Pipelines

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Luis F. Ayala ◽  
Doruk Alp
Keyword(s):  
Natural Gas ◽  
Multiphase Flow ◽  
Fluid Dynamic ◽  
Standard Technique ◽  
Rate Of Change ◽  
Entire Length ◽  
Governing Equations ◽  
Two Phase ◽  
Natural Gas Pipelines ◽  
Common Technique

Marching algorithms are the rule rather than the exception in the determination of pressure distribution in long multiphase-flow pipes, both for the case of pipelines and wellbores. This type of computational protocol is the basis for most two-phase-flow software and it is presented by textbooks as the standard technique used in steady state two-phase analysis. Marching algorithms acknowledge the fact that the rate of change of common fluid flow parameters (such as pressure, temperature, and phase velocities) is not constant but varies along the pipe axis while performing the integration of the governing equations by dividing the entire length into small pipe segments. In the marching algorithm, governing equations are solved for small single sections of pipe, one section at a time. Calculated outlet conditions for a particular segment are then propagated to the next segment as its prescribed inlet condition. Calculation continues in a “marching” fashion until the entire length of the pipe has been integrated. In this work, several examples are shown where this procedure might no longer accurately represent the physics of the flow for the case of natural gas flows with retrograde condensation. The implications related to the use of this common technique are studied, highlighting its potential lack of compliance with the actual physics of the flow for selected examples. This paper concludes by suggesting remedies to these problems, supported by results, showing considerable improvement in fulfilling the actual constraints imposed by the set of simultaneous fluid dynamic continuum equations governing the flow.

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