Measurements of the Stack Metal Temperature During a Natural Gas Blowdown Event Through a Full-Bore Blowdown Valve

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
C. Hartloper ◽  
K. K. Botros ◽  
J. de Vries
Keyword(s):  
Natural Gas ◽  
Compressible Flow ◽  
Flow Model ◽  
Recovery Factor ◽  
Coefficient Of Determination ◽  
Test Cases ◽  
Measured Temperature ◽  
Gas Temperature ◽  
Empirical Correlations ◽  
Temperature Recovery

Experiments were used in conjunction with a compressible flow model to investigate the temperature recovery phenomenon along a blowdown stack during a high-pressure natural gas pipeline blowdown. The test rig involved instrumented 2 in. blowdown stacks mounted on a full-bore valve. Stacks with two wall thicknesses and stagnation pressures of approximately 3000 kPa-a and 5600 kPa-g were tested, giving a total of four test cases. Using the compressible flow model, which was calibrated using static pressure measurements, the stack-gas temperature was calculated to range from −38 °C to −18 °C for the four test cases. The respective stack wall temperatures were measured to range between −13 °C and 0 °C; thus, the temperature recovery ranged between 18 °C and 26 °C. Empirical correlations available in the literature, which were developed for aeronautical applications, were tested against the experimental results. Poor agreement was found between the measured temperature recovery factor and that predicted by five empirical correlations: the coefficient of determination (R2) between the measured and correlation-calculated recovery factor was found to be negative for all five correlations.

Measurements of Blowdown Thrust Loading in Natural Gas Facilities

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
K. K. Botros ◽  
H. Charette ◽  
M. Martens ◽  
M. Beckel ◽  
G. Szuch
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Compressible Flow ◽  
Gas Flow ◽  
Flow Model ◽  
Stagnation Pressure ◽  
Flow Meters ◽  
One Dimensional ◽  
Pressure Losses ◽  
Modeling Approach

Abstract The thrust loading on a vertical blowdown stack during a natural gas blowdown was investigated using a combined experimental and modeling approach. A gravimetric vessel initially at 4000 kPa-g was blown down through two geometrically different stack assemblies. Thrust loads were measured using a dynamic weigh scale typically used for gravimetric calibration of gas flow meters. A one-dimensional (1D) compressible flow model, calibrated using the experimental data, revealed stagnation pressure losses at the entrance to the riser, resulting in lower thrust loads. A comparison between thrust loading obtained from the measurements and the 1D compressible flow model is presented. This work shows that the analytical flow model predicts the blowdown thrust loads within ±30%.

Models and Methods of Determining the Minimum Stack Metal Temperature During Sonic Blowdown of Natural Gas

2014 ◽  
Author(s):  
C. Hartloper ◽  
K. K. Botros ◽  
E. Abdalgawad ◽  
S. Reid
Keyword(s):  
Boundary Layer ◽  
Natural Gas ◽  
Wall Temperature ◽  
Steel Grade ◽  
Metal Temperature ◽  
Suitable Model ◽  
Gas Temperature ◽  
Flow Reynolds Number ◽  
Flow Through ◽  
Temperature Recovery

During a natural gas blowdown event, the flow through the blowdown stack is either sonic or supersonic at the stack exit. In this case, the temperature of the gas at the stack exit can drop significantly as the gas enthalpy is converted to kinetic energy. Depending on the initial pipeline temperature, it is possible for the gas temperature at the stack exit to drop below the minimum metal temperature specification of the stack steel grade. Traditionally in this case it is assumed that the blowdown-stack metal temperature follows the gas temperature; therefore, it would also drop below this minimum temperature. However, analogous to the decrease in the temperature of the gas as the velocity increases, the gas will increase in temperature as the velocity decreases near the wall of the stack due to the boundary layer. As such, the blowdown-stack wall temperature will not decrease to the same extent as the bulk gas temperature during the blowdown event. This phenomenon is referred to as wall temperature recovery. This paper describes the various models and methods for determining the extent of this temperature recovery via a parameter known as “recovery factor” which is a function of the flow Reynolds number, Prandtl number, Mach number, etc. These methods are evaluated and compared for several pipeline conditions, and the most suitable model is determined. It is recommended that fundamental blowdown testing on natural gas be conducted on well instrumented full-bore blowdown stack to validate the predictions by these methods.

Optimization of fuel consumption in natural gas city gate station based on gas hydrate temperature (Case study: Abbas Abad station)

2018 ◽  
Vol 30 (3) ◽  
pp. 408-426 ◽  
Author(s):  
Mahdi Deymi-Dashtebayaz ◽  
Morteza Khorsand ◽  
Hamid Reza Rahbari
Keyword(s):  
Natural Gas ◽  
Fuel Consumption ◽  
Gas Hydrate ◽  
Carbon Tax ◽  
Measured Temperature ◽  
Gas Temperature ◽  
Temperature Regulator ◽  
Natural Gas Pipelines ◽  
The City

A new approach has been presented for optimization of fuel consumption in the natural gas city gate station. In the city gate station, the temperature drops because of pressure drop has been occurred. In this case, the gas temperature may be reached to natural gas hydrates’ temperature and therefore natural gas pipelines are blocked. To avoid this condition, natural gas is preheated. Heating of natural gas should be in the range to avoid the gas hydrated temperature as well as, if possible, lower fuel consumption. For this purpose, the minimum possible temperature regulator output has been defined. The minimum temperature is based on gas hydrate temperature and has been calculated by applying fundamental thermodynamic equations and the equation of state. For validation of proposed method, the results have been compared to the measured temperature of Abbas Abad CGS. The validation shows that the proposed method has reduced fuel consumption by about 35%. The results show the price of reduced fuel consumption and carbon tax has been dropped in a year, also producing carbon dioxide because of incomplete combustion is significantly reduced.

Lime kiln conversion from coke to natural gas operation – an option in direction of sustainable energy

2020 ◽  
pp. 431-434
Author(s):  
Oliver Arndt
Keyword(s):  
Natural Gas ◽  
New Technology ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Gaseous Fuels ◽  
Lime Kiln ◽  
Lime Kilns ◽  
Co2 Balance ◽  
Exhaust Gas Temperature

This paper deals with the conversion of coke fired lime kilns to gas and the conclusions drawn from the completed projects. The paper presents (1) the decision process associated with the adoption of the new technology, (2) the necessary steps of the conversion, (3) the experiences and issues which occurred during the first campaign, (4) the impacts on the beet sugar factory (i.e. on the CO2 balance and exhaust gas temperature), (5) the long term impressions and capabilities of several campaigns of operation, (6) the details of available technologies and (7) additional benefits that would justify a conversion from coke to natural gas operation on existing lime kilns. (8) Forecast view to develop systems usable for alternative gaseous fuels (e.g. biogas).

Laminar flame speed correlations for methane, ethane, propane and their mixtures, and natural gas and gasoline for spark-ignition engine simulations

2017 ◽  
Vol 18 (9) ◽  
pp. 951-970 ◽  
Author(s):  
Riccardo Amirante ◽  
Elia Distaso ◽  
Paolo Tamburrano ◽  
Rolf D Reitz
Keyword(s):  
Natural Gas ◽  
Laminar Flame ◽  
Spark Ignition ◽  
Flame Speed ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Computational Time ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Empirical Correlations

The laminar flame speed plays an important role in spark-ignition engines, as well as in many other combustion applications, such as in designing burners and predicting explosions. For this reason, it has been object of extensive research. Analytical correlations that allow it to be calculated have been developed and are used in engine simulations. They are usually preferred to detailed chemical kinetic models for saving computational time. Therefore, an accurate as possible formulation for such expressions is needed for successful simulations. However, many previous empirical correlations have been based on a limited set of experimental measurements, which have been often carried out over a limited range of operating conditions. Thus, it can result in low accuracy and usability. In this study, measurements of laminar flame speeds obtained by several workers are collected, compared and critically analyzed with the aim to develop more accurate empirical correlations for laminar flame speeds as a function of equivalence ratio and unburned mixture temperature and pressure over a wide range of operating conditions, namely [Formula: see text], [Formula: see text] and [Formula: see text]. The purpose is to provide simple and workable expressions for modeling the laminar flame speed of practical fuels used in spark-ignition engines. Pure compounds, such as methane and propane and binary mixtures of methane/ethane and methane/propane, as well as more complex fuels including natural gas and gasoline, are considered. A comparison with available empirical correlations in the literature is also provided.

The Effect of Turbulence on Momentum and Heat Transport in Packed Beds with Low Tube to Particle Diameter Ratio

2018 ◽  
Vol 16 (11) ◽  
Author(s):  
F. I. Molina-Herrera ◽  
C. O. Castillo-Araiza ◽  
H. Jiménez-Islas ◽  
F. López-Isunza
Keyword(s):  
Thermal Conductivity ◽  
Heat Transport ◽  
Mass Flux ◽  
Flow Model ◽  
Particle Diameter ◽  
Packed Bed ◽  
Diameter Ratio ◽  
Packed Beds ◽  
Measured Temperature ◽  
Orthogonal Collocation

Abstract This is a theoretical study about the influence of turbulence on momentum and heat transport in a packed-bed with low tube to particle diameter ratio. The hydrodynamics is given here by the time-averaged Navier-Stokes equations including Darcy and Forchheimer terms, plus a κ-ε two-equation model to describe a 2D pseudo-homogeneous medium. For comparison, an equivalent conventional flow model has also been tested. Both models are coupled to a heat transport equation and they are solved using spatial discretization with orthogonal collocation, while the time derivative is discretized by an implicit Euler scheme. We compared the prediction of radial and axial temperature observations from a packed-bed at particle Reynolds numbers (Rep) of 630, 767, and 1000. The conventional flow model uses effective heat transport parameters: wall heat transfer coefficient (hw) and thermal conductivity (keff), whereas the turbulent flow model includes a turbulent thermal conductivity (kt), estimating hw via least-squares with Levenberg-Marquardt method. Although predictions of axial and radial measured temperature profiles with both models show small differences, the calculated radial profiles of the axial velocity component are very different. We demonstrate that the model that includes turbulence compares well with mass flux measurements at the packed-bed inlet, yielding an error of 0.77 % in mass flux balance at Rep = 630. We suggest that this approach can be used efficiently for the hydrodynamics characterization and design and scale-up of packed beds with low tube to particle diameter ratio in several industrial applications.

scholarly journals Correlations to Predict Elemental Compositions and Heating Value of Torrefied Biomass

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2443 ◽  
Author(s):  
Mahmudul Hasan ◽  
Yousef Haseli ◽  
Ernur Karadogan
Keyword(s):  
Carbon Content ◽  
Hydrogen Content ◽  
Woody Biomass ◽  
Coefficient Of Determination ◽  
Mass Yield ◽  
Solid Mass ◽  
Empirical Correlations ◽  
Heating Value ◽  
Torrefied Biomass ◽  
Data Points

Measurements reported in the literature on ultimate analysis of various types of torrefied woody biomass, comprising 152 data points, have been compiled and empirical correlations are developed to predict the carbon content, hydrogen content, and heating value of a torrefied wood as a function of solid mass yield. The range of torrefaction temperature, residence time and solid yield of the collected data is 200–300 °C, 5–60 min and 58–97%, respectively. Two correlations are proposed for carbon content with a coefficient of determination ( R 2 ) of 81.52% and 89.86%, two for hydrogen content with R 2 of 79.01% and 88.45%, and one for higher heating value with R 2 of 92.80%. The root mean square error (RMSE) values of the proposed correlations are 0.037, 0.028, 0.059, 0.043 and 0.023, respectively. The predictability of the proposed relations is examined with an additional set of experimental data and compared with the existing correlations in the literature. The new correlations can be used as a useful tool when designing torrefaction plants, furnaces, or gasifiers operating on torrefied wood.

Research and Design of the Control System for Natural Gas Heater

2013 ◽  
Vol 842 ◽  
pp. 541-545
Author(s):  
Yun Guo ◽  
Zhi Qiang Huang ◽  
Shun Xin Yang
Keyword(s):  
Control System ◽  
Natural Gas ◽  
Power Plants ◽  
Production Efficiency ◽  
Combustion Efficiency ◽  
Gas Temperature ◽  
Technical Requirements ◽  
Real Time Measurement ◽  
And Control ◽  
Measurement And Control

Natural gas heaters are widely used in gas-fired power plants to meet the combustion needs and to improve the combustion efficiency. For the control features and technical requirements of the natural gas heater, the computer automatic control system for natural gas heater has been designed,and realizes the temperature and liquid level real time measurement and control. The system increases significantly the control accuracy of natural gas temperature, eliminates potential unsafety and improves production efficiency.

scholarly journals Improving Efficiency, Extending the Maximum Load Limit and Characterizing the Control-Related Problems Associated With Higher Loads in a 6-Cylinder Heavy-Duty Natural Gas Engine

2010 ◽  
Author(s):  
Mehrzad Kaiadi ◽  
Per Tunestal ◽  
Bengt Johansson
Keyword(s):  
Natural Gas ◽  
Compression Ratio ◽  
Diesel Engines ◽  
Maximum Load ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Heavy Duty ◽  
Load Limit ◽  
Overall Efficiency ◽  
Exhaust Gas Temperature

High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition Natural Gas engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Most of the heavy duty NG engines are diesel engines which are converted for SI operation. These engine’s components are in common with the diesel-engine which put limits on higher exhaust gas temperature. The engines have lower maximum load level than the corresponding diesel engines. This is mainly due to the lower density of NG, lower compression ratio and limits on knocking and also high exhaust gas temperature. They also have lower efficiency due to mainly the lower compression ratio and the throttling losses. However performing some modifications on the engines such as redesigning the engine’s piston in a way to achieve higher compression ratio and more turbulence, modifying EGR system and optimizing the turbocharging system will result in improving the overall efficiency and the maximum load limit of the engine. This paper presents the detailed information about the engine modifications which result in improving the overall efficiency and extending the maximum load of the engine. Control-related problems associated with the higher loads are also identified and appropriate solutions are suggested.

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