Ventilation of Gas Turbine Package Enclosures: Design Evaluation Procedure

2006 ◽  
Author(s):  
Hamid Bagheri ◽  
Daniel Vahidi
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Experimental Validation ◽  
Oil And Gas ◽  
Ventilation System ◽  
Flow Distribution ◽  
Evaluation Procedure ◽  
Co2 Injection ◽  
Complex Flow ◽  
Numerical Predictions

Gas turbine packages provide a major portion of mechanical drive and power supply for the offshore operating oil and gas platforms. These packages are typically installed in acoustic enclosures, which need to be ventilated for both removing the heat rejected from the engine and package components, and properly diluting explosive gasses in case of a leak. Considering importance of safety and reliability of gas turbine equipment operating in the offshore environment, and also near industrial and populated areas, authors of the paper emphasize the need for experimental validation of a CFD prediction practice for effective ventilation of the turbine package enclosures. In a properly designed acoustic enclosure, ventilation system has to prevent overheating of the electrical and engine control components, as well as, dilution of potential fuel leakages to eliminate stagnant zones that could cause an ignition within enclosure. Conversely, an excessive flow of the vent air may result in masking local fuel leakages, which might pass undetected through explosion protection devices. Therefore, the optimum enclosure ventilation design has to be based on proper vent flow distribution to ensure acceptable temperature distribution within the enclosure, proper flow distribution to ensure no stagnation area, combined with appropriate gas detection setting. In order to achieve an optimum enclosure design, rather complex flow and heat transfer phenomena have to be studied to select the optimal configuration of the vent system. Numerical analysis of the enclosures with commercially available CFD codes is usually based on a number of simplifying assumptions and approximations. Therefore, to satisfy critical safety requirements in the offshore environment, authors of the paper emphasize role of experimental validation of the CFD predictions. The presented paper provides details of the enclosure design validation using a CFD study based on an earlier experimental validation of the numerical predictions. A midsize gas turbine package model was selected to demonstrate this procedure. The main features from the actual engine package were included in the CFD model. Effectiveness of ventilation was studied for both cold and heated engine surfaces. CFD analyses were also carried out for local CO2 injection emulating natural gas leakage. Both scenarios with CO2 and natural gas (methane) leakages were considered reducing uncertainty of predictions due to the differences in the density and buoyancy between these gasses. Based on presented study certain improvements in design of the enclosure were recommended and described in the paper.

scholarly journals Natural Gas

2011 ◽  
Vol 133 (04) ◽  
pp. 52-52
Author(s):  
Rainer Kurz
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Oil And Gas ◽  
Electrical Power ◽  
Offshore Platforms ◽  
Electric Motors ◽  
Turbine Generator ◽  
Associated Gas ◽  
Generator Sets

This article discusses the importance of gas turbines, centrifugal compressors and pumps, and other turbomachines in processes that bring natural gas to the end users. To be useful, the natural gas coming from a large number of small wells has to be gathered. This process requires compression of the gas in several stages, before it is processed in a gas plant, where contaminants and heavier hydrocarbons are stripped from the gas. From the gas plant, the gas is recompressed and fed into a pipeline. In all these compression processes, centrifugal gas compressors driven by industrial gas turbines or electric motors play an important role. Turbomachines are used in a variety of applications for the production of oil and associated gas. For example, gas turbine generator sets often provide electrical power for offshore platforms or remote oil and gas fields. Offshore platforms have a large electrical demand, often requiring multiple large gas turbine generator sets. Similarly, centrifugal gas compressors, driven by gas turbines or by electric motors are the benchmark products to pump gas through pipelines, anywhere in the world.

Experimental Assessment of the Emissions Benefits of a Ceramic Gas Turbine Combustor

1996 ◽  
Author(s):  
K. O. Smith ◽  
A. Fahme
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Flow Distribution ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Experimental Assessment ◽  
Industrial Gas Turbine ◽  
Combustor Liner

Three subscale, cylindrical combustors were rig tested on natural gas at typical industrial gas turbine operating conditions. The intent of the testing was to determine the effect of combustor liner cooling on NOx and CO emissions. In order of decreasing liner cooling, a metal louvre-cooled combustor, a metal effusion-cooled combustor, and a backside-cooled ceramic (CFCC) combustor were evaluated. The three combustors were tested using the same lean-premixed fuel injector. Testing showed that reduced liner cooling produced lower CO emissions as reaction quenching near the liner wall was reduced. A reduction in CO emissions allows a reoptimization of the combustor air flow distribution to yield lower NOx emissions.

Experimental Study and Modeling of Autoignition of Natural Gas/Air-Mixtures Under Gas Turbine Relevant Conditions

2005 ◽  
Author(s):  
Andreas Koch ◽  
Clemens Naumann ◽  
Wolfgang Meier ◽  
Manfred Aigner
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Ignition Delay Time ◽  
Evaluation Procedure ◽  
Ignition Process ◽  
Ignition Delay Times ◽  
Delay Times

The objective of this work was the improvement of methods for predicting autoignition in turbulent flows of different natural gas mixtures and air. Measurements were performed in a mixing duct where fuel was laterally injected into a turbulent flow of preheated and pressurized air. To study the influence of higher order hydrocarbons on autoignition, natural gas was mixed with propane up to 20% by volume at pressures up to 15 bar. During a measurement cycle, the air temperature was increased until autoignition occurred. The ignition process was observed by high-speed imaging of the flame chemiluminescence. In order to attribute a residence time (ignition delay time) to the locations where autoignition was detected the flow field and its turbulent fluctuations were simulated by numerical codes. These residence times were compared to calculated ignition delay times using detailed chemical simulations. The measurement system and data evaluation procedure are described and preliminary results are presented. An increase in pressure and in fraction of propane in the natural gas both reduced the ignition delay time. The measured ignition delay times were systematically longer than the predicted ones for temperatures above 950 K. The results are important for the design process of gas turbine combustors and the studies also demonstrate a procedure for the validation of design tools under relevant conditions.

scholarly journals Effect of Air Extraction for Cooling and/or Gasification on Combustor Flow Uniformity

1998 ◽  
Author(s):  
T. Wang ◽  
J. S. Kapat ◽  
W. R. Ryan ◽  
I. S. Diakunchak ◽  
R. L. Bannister
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Field Experiments ◽  
Fuel Injection ◽  
Flow Distribution ◽  
Flow Uniformity ◽  
Complex Flow ◽  
Local Flow

Reducing emissions is an important issue facing gas turbine manufacturers. Almost all of the previous and current research and development for reducing emissions has focused, however, on flow, heat transfer, and combustion behavior in the combustors or on the uniformity of fuel injection without placing strong emphasis on the flow uniformity entering the combustors. In response to the incomplete understanding of the combustor’s inlet air flow field, experiments were conducted in a 48% scale, 360° model of the diffuser-combustor section of an industrial gas turbine. In addition, the effect of air extraction for cooling or gasification on the flow distributions at the combustors’ inlets was also investigated. Three different air extraction rates were studied: 0% (baseline), 5% (airfoil cooling), and 20% (for coal gasification). The flow uniformity was investigated for two aspects: (a) global uniformity, which compared the mass flow rates of combustors at different locations relative to the extraction port, and (b) local uniformity, which examined the circumferential flow distribution into each combustor. The results indicate that even for the baseline case with no air extraction there was an inherent local flow aonuniformity of 10 ∼ 20% at the inlet of each combustor due to the complex flow field in the dump diffuser and the blockage effect of the cross-flame tube. More flow was seen in the portion further away from the gas turbine center axis. The effect of 5% air extraction was small. Twenty-percent air extraction introduced approximately 35% global flow asymmetry diametrically across the dump diffuser. The effect of air extraction on the combustor’s local flow uniformity varied with the distances between the extraction port and each individual combustor. Longer top hats were installed with the initial intention of increasing flow mixing prior to entering the combustor. However, the results indicated that longer top hats do not improve the flow uniformity; sometimes, adverse effects can be seen. Although a specific geometry was selected for this study, the results provide sufficient generality to benefit other industrial gas turbines.

Correction: Numerical predictions of pollutant emissions of novel natural gas low NOx burners for heavy duty gas turbine

2018 ◽  
Author(s):  
Daniele Pampaloni ◽  
Pier Carlo Nassini ◽  
Simone Paccati ◽  
Lorenzo Palanti ◽  
Antonio Andreini ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Pollutant Emissions ◽  
Heavy Duty ◽  
Numerical Predictions ◽  
Heavy Duty Gas Turbine

Experimental Studies of Air Extraction for Cooling and/or Gasification in Gas Turbine Applications

1997 ◽  
Vol 119 (4) ◽  
pp. 807-814 ◽  
Author(s):  
J. S. Kapat ◽  
T. Wang ◽  
W. R. Ryan ◽  
I. S. Diakunchak ◽  
R. L. Bannister
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Single Port ◽  
Reverse Flow ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Flow Distribution ◽  
Complex Flow ◽  
Local Flow ◽  
Industrial Gas Turbine

This paper describes an experimental study on how the flow field inside the dump diffuser of an industrial gas turbine is affected by air extraction through a single port on the shell around the dump diffuser. A subscale, 360 deg model of the diffuser-combustor section of an advanced developmental industrial gas turbine was used in this study. The experiments were performed under cold flow conditions, which can be scaled to actual machine operation. Three different conditions were experimentally studied: 0, 5, and 20 percent air extraction. It was found that air extraction, especially extraction at the 20 percent rate, introduced flow asymmetry inside the dump diffuser and, in some locations, increased the local flow recirculations. This indicated that when air was extracted through a single port on the shell, the performance of the dump diffuser was adversely affected with an approximate 7.6 percent increase of the total pressure loss, and the air flow into the combustors did not remain uniform. The global flow distribution was shown to be approximately 35 percent nonuniform diametrically across the dump diffuser. Although a specific geometry was selected, the results provide sufficient generality for improving understanding of the complex flow behavior in the reverse flow diffuser-combustor sections of gas turbines under the influence of various air extractions.

Unsteady Aerodynamics and Forced Response Studies on Aeroderivative Gas Turbine Exhaust System

2014 ◽  
Author(s):  
Luca Di Mare ◽  
Deepak Thirumurthy ◽  
Jeffrey S. Green ◽  
John Myers
Keyword(s):  
Low Power ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Unsteady Aerodynamics ◽  
Exhaust System ◽  
Forced Response ◽  
Operating Conditions ◽  
Complex Flow ◽  
Numerical Predictions ◽  
Exhaust Systems

Industrial and aeroderivative gas turbines use exhaust systems for flow diffusion and pressure recovery. These processes result in a three-dimensional, unsteady, turbulent, and complex flow in the exhaust diffusers. The downstream balance-of-plant systems such as heat recovery steam generators or selective catalytic systems require, in general, a steady, uniform flow out of the exhaust system. Aeroderivative gas turbines for power generation application have a wide operational envelope. Even though the exhaust systems are designed for 70% load to 110% load, its performance is significantly altered at low power operations. Application of gas turbines at low power can increase exhaust diffuser vibrations because of diffuser flow separations and wakes from the last stage of the power turbine. Aerodynamic excitations which result in excessive structural vibration can cause the units to trip and the power plant to stop, resulting in customer revenue loss. The primary motivation for this research is to investigate an aerodynamic mechanism to ensure reliable operation of the exhaust system by identifying the regimes where aerodynamic instabilities can occur. In-house and university supported initiative to predict unsteady aerodynamics at low power conditions shows the presence of turbulent and time dependent flow. The frequency spectrum results are discussed for low power and high power gas turbine operating conditions. The numerical predictions are in good agreement with test results.

Numerical predictions of pollutant emissions of novel natural gas low NOx burners for heavy duty gas turbine

2018 ◽  
Author(s):  
Daniele Pampaloni ◽  
Pier Carlo Nassini ◽  
Simone Paccati ◽  
Lorenzo Palanti ◽  
Antonio Andreini ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Pollutant Emissions ◽  
Heavy Duty ◽  
Numerical Predictions ◽  
Heavy Duty Gas Turbine

Experimental Studies of Air Extraction for Cooling and/or Gasification in Gas Turbine Applications

1996 ◽  
Author(s):  
J. S. Kapat ◽  
T. Wang ◽  
W. R. Ryan ◽  
I. S. Diakunchak ◽  
R. L. Bannister
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Single Port ◽  
Reverse Flow ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Flow Distribution ◽  
Complex Flow ◽  
Local Flow ◽  
Industrial Gas Turbine

This paper describes an experimental study on how the flow field inside the dump diffuser of an industrial gas turbine is affected by air extraction through a single port on the shell around the dump diffuser. A sub-scale, 360° model of the diffuser-combustor section of an advanced developmental industrial gas turbine was used in this study. The experiments were performed under cold flow conditions which can be scaled to actual machine operation. Three different conditions were experimentally studied: 0%, 5%, and 20% air extraction. It was found that air extraction, especially extraction at the 20% rate, introduced flow asymmetry inside the dump diffuser and, in some locations, increased the local flow recirculations. This indicated that when air was extracted through a single port on the shell, the performance of the dump diffuser was adversely affected with an approximate 7.6% increase of the total pressure loss, and the air flow into the combustors did not remain uniform. The global flow distribution was shown to be approximately 35% nonuniform diametrically across the dump diffuser. Although a specific geometry was selected, the results provide sufficient generality for improving understanding of the complex flow behavior in the reverse flow diffuser-combustor sections of gas turbines under the influence of various air extractions.

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