Propagation of Turbulent Natural Gas/Air Flames in Tubing With 90° Bends

2003 ◽  
Vol 125 (4) ◽  
pp. 304-310
Author(s):  
Michael D. Morgan ◽  
S. A. (Raj) Mehta ◽  
T. J. Al-Himyary ◽  
R. G. (Gord) Moore
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Small Diameter ◽  
Industrial Applications ◽  
Turbulent Flames ◽  
Process Equipment ◽  
Pressure Data ◽  
Flammable Gas ◽  
Internal Volume ◽  
Temperature Responses

Anytime flammable gas mixtures are handled, there is a risk of combustion. This is particularly true in many industrial applications where space is limited and equipment is located near sources of ignition. Unfortunately, there is a lack of understanding of combustion phenomena within process equipment such as mufflers, rotating blowout preventers, liquid traps, and dry gas seal assemblies. These vessels have small internal volumes, complex internal geometries, and are connected using small diameter piping. This paper discusses the results of a parametric study which was carried out to establish the nature of combustion within such vessels and tubing. The test vessel had an internal volume of 7 in3 (115 ml) and the tubing had a nominal diameter of 0.5 in (1.27 mm). Flowing, turbulent, pre-mixed natural gas/air mixtures were used. The study did not attempt to increase turbulence using devices such as mesh screens or attempt to stabilize the flame. The results from a representative sample of 76 tests, from the 5,000+ tests that have been completed, are discussed herein. Typical pressure and temperature responses are presented and analyzed. It is demonstrated that flames can be remotely detected using only high speed pressure data. Turbulent flames were formed whose velocity was found to be linearly dependant on Reynolds number.

Ignition and Propagation of Flammable Gas Mixtures in Vessels With Small, Complex Geometries

2002 ◽  
Author(s):  
Michael D. Morgan ◽  
S. A. Mehta ◽  
T. J. Al-Himyary ◽  
R. G. Moore
Keyword(s):  
High Speed ◽  
Small Diameter ◽  
Gas Mixtures ◽  
Operating Conditions ◽  
Process Equipment ◽  
Testing System ◽  
Real Process ◽  
Small Complex ◽  
Flammable Gas ◽  
Temperature Responses

Anytime flammable gas mixtures are handled, there is a risk of combustion hazard. This is particularly true in many oilfield applications where space is limited and equipment is located near sources of ignition. Unfortunately, there is a lack of understanding of combustion phenomena within process equipment such as mufflers, rotating blowout preventers, liquid traps, and dry gas seal assemblies. These vessels have small internal volumes, complex internal geometries, and are often connected using small diameter piping. This paper discusses the results of a parametric study which was carried out to establish the nature of combustion within small diameter vessels and exhaust tubing. Flowing, pre-mixed fuel/air mixtures were used. This study has been conducted using a testing system capable of emulating real process equipment under realistic field operating conditions, for example, flow rates, back pressures, and fuel type. The results from a representative sample of 79 tests, from the 5,000+ tests that have been completed, are discussed herein. Typical pressure and temperature responses are presented and analysed. In addition, methods of detecting the presence of combustion are discussed. In particular, it is demonstrated that flames can be remotely detected and located using only high speed pressure data.

The Research of Internal Corrosion Location Prediction Technology in the Typical Pipeline Components of Natural Gas Gathering Pipeline

2014 ◽  
Vol 1052 ◽  
pp. 583-590 ◽  
Author(s):  
Hong Lian Ma ◽  
Hui Huang ◽  
Ren Yang He ◽  
Han Qiu Li ◽  
Yong Yang ◽  
...  
Keyword(s):  
Natural Gas ◽  
High Speed ◽  
Detection Efficiency ◽  
Small Diameter ◽  
Field Analysis ◽  
Corrosion Mechanism ◽  
Location Prediction ◽  
Test Results ◽  
Internal Corrosion ◽  
Actual Test

Gathering pipeline is used for transporting crude gas without purification in natural gas mine, it has short transmission distance, small diameter, pressure changes and other characteristics . In the natural gas gathering and transportation process, the carrying effect of high pressure and high speed gas, water, sand, acidic medium and other untreated impurities could induce flow corrosion in gas pipeline, pipeline components (referred to as the tube), and other ancillary facilities interior. According to the actual failure case of an acidic gas mine pipeline, based on the CO2 corrosion mechanism, internal flow field analysis of the model and the actual test results, through comparison of numerical results and actual test results, the article gives a research on corrosion location prediction technology in the typical components of natural gas gathering pipeline. The technology has an important significance to guide field inspection, improve the detection efficiency and defect detection rate, and protect the natural gas mine gathering safety.

The Structure and Propagation Mechanism of Turbulent Flames in High Speed Flow

1955 ◽  
Vol 25 (8) ◽  
pp. 377-384 ◽  
Author(s):  
MARTIN SUMMERFIELD ◽  
SYDNEY H. REITER ◽  
VICTOR KEBELY ◽  
RICHARD W. MASCOLO
Keyword(s):  
High Speed ◽  
Turbulent Flames ◽  
Propagation Mechanism ◽  
High Speed Flow ◽  
Speed Flow

scholarly journals Methane Emissions from Process Equipment at Natural Gas Production Sites in the United States: Liquid Unloadings

2014 ◽  
Vol 49 (1) ◽  
pp. 641-648 ◽  
Author(s):  
David T. Allen ◽  
David W. Sullivan ◽  
Daniel Zavala-Araiza ◽  
Adam P. Pacsi ◽  
Matthew Harrison ◽  
...  
Keyword(s):  
United States ◽  
Natural Gas ◽  
The United States ◽  
Methane Emissions ◽  
Gas Production ◽  
Process Equipment ◽  
Natural Gas Production

Comparison of PIR to PIPESAFE-Based 1% Lethality Zones for Natural Gas Pipelines

2014 ◽  
Author(s):  
Aleksandar Tomic ◽  
Shahani Kariyawasam
Keyword(s):  
Natural Gas ◽  
Small Diameter ◽  
Gas Pipeline ◽  
Accurate Estimation ◽  
Simple Relationship ◽  
Gas Pipelines ◽  
Friction Forces ◽  
Natural Gas Pipelines ◽  
Decay Factor ◽  
Outflow Rate

A lethality zone due to an ignited natural gas release is often used to characterize the consequences of a pipeline rupture. A 1% lethality zone defines a zone where the lethality to a human is greater than or equal to 1%. The boundary of the zone is defined by the distance (from the point of rupture) at which the probability of lethality is 1%. Currently in the gas pipeline industry, the most detailed and validated method for calculating this zone is embodied in the PIPESAFE software. PIPESAFE is a software tool developed by a joint industry group for undertaking quantitative risk assessments of natural gas pipelines. PIPESAFE consequence models have been verified in laboratory experiments, full scale tests, and actual failures, and have been extensively used over the past 10–15 years for quantitative risk calculations. The primary advantage of using PIPESAFE is it allows for accurate estimation of the likelihood of lethality inside the impacted zone (i.e. receptors such as structures closer to the failure are subject to appropriately higher lethality percentages). Potential Impact Radius (PIR) is defined as the zone in which the extent of property damage and serious or fatal injury would be expected to be significant. It corresponds to the 1% lethality zone for a natural gas pipeline of a certain diameter and pressure when thermal radiation and exposure are taken into account. PIR is one of the two methods used to identify HCAs in US (49 CFR 192.903). Since PIR is a widely used parameter and given that it can be interpreted to delineate a 1% lethality zone, it is important to understand how PIR compares to the more accurate estimation of the lethality zones for different diameters and operating pressures. In previous internal studies, it was found that PIR, when compared to the more detailed measures of the 1% lethality zone, could be highly conservative. This conservatism could be beneficial from a safety perspective, however it is adding additional costs and reducing the efficiency of the integrity management process. Therefore, the goal of this study is to determine when PIR is overly conservative and to determine a way to address this conservatism. In order to assess its accuracy, PIR was compared to a more accurate measure of the 1% lethality zone, calculated by PIPESAFE, for a range of different operating pressures and line diameters. Upon comparison of the distances calculated through the application of PIR and PIPESAFE, it was observed that for large diameters pipelines the distances calculated by PIR are slightly conservative, and that this conservativeness increases exponentially for smaller diameter lines. The explanation for the conservatism of the PIR for small diameter pipelines is the higher wall friction forces per volume transported in smaller diameter lines. When these higher friction forces are not accounted for it leads to overestimation of the effective outflow rate (a product of the initial flow rate and the decay factor) which subsequently leads to the overestimation of the impact radius. Since the effective outflow rate is a function of both line pressure and diameter, a simple relationship is proposed to make the decay factor a function of these two variables to correct the excess conservatism for small diameter pipelines.

Study of the Fluid Dynamics of Thin Liquid Films Flowing Down a Vertical String With Counterflow of Gas

2015 ◽  
Author(s):  
Zezhi Zeng ◽  
Gopinath Warrier ◽  
Y. Sungtaek Ju
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Film Thickness ◽  
Liquid Film ◽  
Direct Contact ◽  
High Speed ◽  
Small Diameter ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Liquid Coolant

Direct-contact heat transfer between a falling liquid film and a gas stream yield high heat transfer rates and as such it is routinely used in several industrial applications. This concept has been incorporated by us into the proposed design of a novel heat exchanger for indirect cooling of steam in power plants. The DILSHE (Direct-contact Liquid-on-String Heat Exchangers) module consists of an array of small diameter (∼ 1 mm) vertical strings with hot liquid coolant flowing down them due to gravity. A low- or near-zero vapor pressure liquid coolant is essential to minimize/eliminate coolant loss. Consequently, liquids such as Ionic Liquids and Silicone oils are ideal candidates for the coolant. The liquid film thickness is of the order of 1 mm. Gas (ambient air) flowing upwards cools the hot liquid coolant. Onset of fluid instabilities (Rayleigh-Plateau and/or Kapitza instabilities) result in the formation of a liquid beads, which enhance heat transfer due to additional mixing. The key to successfully designing and operating DILSHE is understanding the fundamentals of the liquid film fluid dynamics and heat transfer and developing an operational performance map. As a first step towards achieving these goals, we have undertaken a parametric experimental and numerical study to investigate the fluid dynamics of thin liquid films flowing down small diameter strings. Silicone oil and air are the working fluids in the experiments. The experiments were performed with a single nylon sting (fishing line) of diameter = 0.61 mm and height = 1.6 m. The inlet temperature of both liquid and air were constant (∼ 20 °C). In the present set of experiments the variables that were parametrically varied were: (i) liquid mass flow rate (0.05 to 0.23 g/s) and (ii) average air velocity (0 to 2.7 m/s). Visualization of the liquid flow was performed using a high-speed camera. Parameters such as base liquid film thickness, liquid bead shape and size, velocity (and hence frequency) of beads were measured from the high-speed video recordings. The effect of gas velocity on the dynamics of the liquid beads was compared to data available in the open literature. Within the range of gas velocities used in the experiments, the occurrence of liquid hold up and/or liquid blow over, if any, were also identified. Numerical simulations of the two-phase flow are currently being performed. The experimental results will be invaluable in validation/refinement of the numerical simulations and development of the operational map.

The Effect of Lewis Number on Instantaneous Flamelet Speed and Position Statistics in Counter-Flow Flames With Increasing Turbulence

2017 ◽  
Author(s):  
Sean D. Salusbury ◽  
Ehsan Abbasi-Atibeh ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Flame Front ◽  
Turbulence Intensity ◽  
High Speed ◽  
Rayleigh Scattering ◽  
Turbulent Flame ◽  
Lewis Number ◽  
Turbulent Flames ◽  
Flame Speed ◽  
Laminar Flames ◽  
Counter Flow

Differential diffusion effects in premixed combustion are studied in a counter-flow flame experiment for fuel-lean flames of three fuels with different Lewis numbers: methane, propane, and hydrogen. Previous studies of stretched laminar flames show that a maximum reference flame speed is observed for mixtures with Le ≳ 1 at lower flame-stretch values than at extinction, while the reference flame speed for Le ≪ 1 increases until extinction occurs when the flame is constrained by the stagnation point. In this work, counter-flow flame experiments are performed for these same mixtures, building upon the laminar results by using variable high-blockage turbulence-generating plates to generate turbulence intensities from the near-laminar u′/SLo=1 to the maximum u′/SLo achievable for each mixture, on the order of u′/SLo=10. Local, instantaneous reference flamelet speeds within the turbulent flame are extracted from high-speed PIV measurements. Instantaneous flame front positions are measured by Rayleigh scattering. The probability-density functions (PDFs) of instantaneous reference flamelet speeds for the Le ≳ 1 mixtures illustrate that the flamelet speeds are increasing with increasing turbulence intensity. However, at the highest turbulence intensities measured in these experiments, the probability seems to drop off at a velocity that matches experimentally-measured maximum reference flame speeds in previous work. In contrast, in the Le ≪ 1 turbulent flames, the most-probable instantaneous reference flamelet speed increases with increasing turbulence intensity and can, significantly, exceed the maximum reference flame speed measured in counter-flow laminar flames at extinction, with the PDF remaining near symmetric for the highest turbulence intensities. These results are reinforced by instantaneous flame position measurements. Flame-front location PDFs show the most probable flame location is linked both to the bulk flow velocity and to the instantaneous velocity PDFs. Furthermore, hydrogen flame-location PDFs are recognizably skewed upstream as u′/SLo increases, indicating a tendency for the Le ≪ 1 flame brush to propagate farther into the unburned reactants against a steepening average velocity gradient.

scholarly journals Using thermal energy storage to replace natural gas in commercial/industrial applications

2018 ◽  
Author(s):  
Rhys Jacob ◽  
Martin Belusko ◽  
Ming Liu ◽  
Wasim Saman ◽  
Frank Bruno
Keyword(s):  
Energy Storage ◽  
Natural Gas ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Industrial Applications
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