Reactor Network Modeling of Stability and Emissions of Hydrogen and Natural Gas Blends for a Piloted Gas Turbine Combustor

2020 ◽  
Author(s):  
Candy Hernandez ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Chemical Reactor ◽  
Experimental Results ◽  
Fuel Composition ◽  
Gas Turbine Combustor ◽  
Flammability Limits ◽  
Lean Premixed ◽  
Carbon Molecules

Abstract Lean-premixed (LPM) gas turbines have been developed for stationary power generation in efforts to reduce emissions due to strict air quality standards. Lean-premixed operation is beneficial as it reduces combustor temperatures, thus decreasing NOx formation and unburned hydrocarbons. However, tradeoffs occur between system performance and turbine emissions. Efforts to minimize tradeoffs between stability and emissions include the addition of hydrogen to natural gas, a common fuel used in stationary gas turbines. The addition of hydrogen is promising for both increasing combustor stability and further reducing emissions because of its wide flammability limits allowing for lower temperature operation, and lack of carbon molecules. Other efforts to increase gas turbine stability include the usage of a non-lean pilot flame to assist in stabilizing the main flame. By varying fuel composition for both the main and piloted flows of a gas turbine combustor, the effect of hydrogen addition on performance and emissions can be systematically evaluated. In the present work, computational fluid dynamics (CFD) and chemical reactor networks (CRN) are created to evaluate stability (LBO) and emissions of a gas turbine combustor by utilizing fuel and flow rate conditions from former hydrogen and natural gas experimental results. With CFD and CRN analysis, the optimization of parameters between fuel composition and main/pilot flow splits can provide feedback for minimizing pollutants while increasing stability limits. The results from both the gas turbine model and former experimental results can guide future gas turbine operation and design.

Enhanced Gas Turbine Combustor Performance Using H2-Enriched Natural Gas

1999 ◽  
Author(s):  
Jeffrey N. Phillips ◽  
Richard J. Roby
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Flame Speed ◽  
Gas Turbine Combustor ◽  
Flammability Limits ◽  
Combustion Performance ◽  
Exhaust Heat ◽  
Efficient Combustion

A screening level study has been carried out to examine the potential of using H2-enriched natural gas to improve the combustion performance of gas turbines. H2 has wider flammability limits and a higher flame speed than methane. Many previous studies have shown that when H2 is added to fuel, more efficient combustion and lower emissions will result. However, to date no commercial attempt has been made to improve the combustion performance of a natural gas-fired gas turbine by supplementing the fuel with H2. Four potential options for supplementing natural gas with H2 have been analyzed. Three of these options use the exhaust heat of the gas turbine either directly or indirectly to partially reform methane. The fourth option uses liquid H2 supplied from an industrial gas producer.

Fuel Flexibility Influences on Premixed Combustor Blowout, Flashback, Autoignition and Instability

2006 ◽  
Author(s):  
Tim Lieuwen ◽  
Vince McDonell ◽  
Eric Petersen ◽  
Domenic Santavicca
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Dynamic Stability ◽  
Current Understanding ◽  
Fuel Composition ◽  
Fuel Flexibility ◽  
Lean Premixed ◽  
Gas Fuel ◽  
The Impact ◽  
Underlying Processes

This paper addresses the impact of fuel composition on the operability of lean premixed gas turbine combustors. This is an issue of current importance due to variability in the composition of natural gas fuel supplies and interest in the use of syngas fuels. Of particular concern is the effect of fuel composition on combustor blowout, flashback, dynamic stability, and autoignition. This paper reviews available results and current understanding of the effects of fuel composition on the operability of lean premixed combustors. It summarizes the underlying processes that must be considered when evaluating how a given combustor’s operability will be affected as fuel composition is varied.

Development of a Natural Gas-Fired, Ultra-Low NOx Can Combustor for an 800 KW Gas Turbine

1991 ◽  
Author(s):  
K. O. Smith ◽  
A. C. Holsapple ◽  
H. K. Mak ◽  
L. Watkins
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Premixed Combustion ◽  
Experimental Results ◽  
Nox Emissions ◽  
Variable Geometry ◽  
Lean Premixed Combustion ◽  
Full Load ◽  
Primary Zone ◽  
Lean Premixed

The experimental results from the rig testing of an ultra-low NOx, natural gas-fired combustor for an 800 to 1000 kw gas turbine are presented. The combustor employed lean-premixed combustion to reduce NOx emissions and variable geometry to extend the range over which low emissions were obtained. Testing was conducted using natural gas and methanol. Testing at combustor pressures up to 6 atmospheres showed that ultra-low NOx emissions could be achieved from full load down to approximately 70% load through the combination of lean-premixed combustion and variable primary zone airflow.

Prediction of NOx and CO Emissions from an Industrial Lean-Premixed Gas Turbine Combustor Using a Chemical Reactor Network Model

2013 ◽  
Vol 27 (3) ◽  
pp. 1643-1651 ◽  
Author(s):  
Jungkyu Park ◽  
Truc Huu Nguyen ◽  
Daero Joung ◽  
Kang Yul Huh ◽  
Min Chul Lee
Keyword(s):  
Gas Turbine ◽  
Network Model ◽  
Chemical Reactor ◽  
Gas Turbine Combustor ◽  
Chemical Reactor Network ◽  
Lean Premixed ◽  
Reactor Network

Micro Gas Turbine Combustor Emissions Evaluation Using the Chemical Reactor Modelling Approach

2007 ◽  
Author(s):  
Carmine Russo ◽  
Giulio Mori ◽  
Vyacheslav V. Anisimov ◽  
Joa˜o Parente
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Atmospheric Pressure ◽  
Chemical Reactor ◽  
Exhaust Emissions ◽  
Operating Conditions ◽  
Gas Turbine Combustor ◽  
Micro Gas Turbine ◽  
Simulation Results ◽  
Modelling Approach

Chemical Reactor Modelling approach has been applied to evaluate exhaust emissions of the newly designed ARI100 (Patent Pending) recuperated micro gas turbine combustor developed by Ansaldo Ricerche SpA. The development of the chemical reactor network has been performed based on CFD reacting flow analysis, obtained with a global 2-step reaction mechanism, applying boundary conditions concerning the combustion chamber at atmospheric pressure, with 100% of thermal load and fuelled with natural gas. The network consists of 11 ideal reactors: 6 perfectly stirred reactors, and 5 plug flow reactors, including also 13 mixers and 12 splitters. Simulations have been conducted using two detailed reaction mechanisms: GRI Mech 3.0 and Miller & Bowman reaction mechanisms. Exhaust emissions have been evaluated at several operating conditions, obtained at different pressure, and considering different fuel gases, as natural gas and a high H2 content SYNGAS fuel. Furthermore, emissions at different thermal loads have been investigated when natural gas at atmospheric pressure is fuelled. Simulation results have been compared with those obtained from combustion experimental campaign. CO and NOx emissions predicted with CRM approach closely match experimental results at representative operating conditions. Ongoing efforts to improve the proposed reactors network should allow extending the range of applicability to those operating conditions whose simulation results are not completely satisfying. Given the small computational effort required, and the accuracy in predicting combustor experimental exhaust emissions, both CO and NOx, the CRM approach turnout to be an efficient way to reasonably evaluate exhaust emissions of a micro gas turbine combustor.

Impact of Fuel Composition on Blow Off and Flashback in Swirl Stabilized Lean Premixed Combustion

2013 ◽  
Author(s):  
Amin Akbari ◽  
Vincent McDonell ◽  
Scott Samuelsen
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Pollutant Emissions ◽  
Fuel Composition ◽  
Pure Hydrogen ◽  
Combustion Properties ◽  
Lean Premixed ◽  
The Impact

Co firing of natural gas with renewable fuels such as hydrogen can reduce greenhouse gas emissions, and meet other sustainability considerations. At the same time, adding hydrogen to natural gas alters combustion properties, such as burning speeds, heating values, flammability limits, and chemical characteristics. It is important to identify how combustion stability relates to fuel mixture composition in industrial gas turbines and burners and correlate such behavior to fuel properties or operating conditions. Ultimately, it is desired to predict and prevent operability issues when designing a fuel flexible gas turbine combustor. Fuel interchangeability is used to describe the ability of a substitute fuel composition to replace a baseline fuel without significantly altering performance and operation. Any substitute fuel, while maintaining the same heating load as the baseline fuel, must also provide stable combustion with low pollutant emissions. Interchangeability indices try to predict the impact of fuel composition on lean blowoff and flashback. Correlations for operability limits have been reported, though results are more consistent for blowoff compared to flashback. Yet, even for blowoff, some disagreement regarding fuel composition effects are evident. In the present work, promising correlations and parameters for lean blow off and flashback in a swirl stabilized lean premixed combustor are evaluated. Measurements are conducted for fuel compositions ranging from pure natural gas to pure hydrogen under different levels of preheat and air flow rates. The results are used to evaluate the ability of existing approaches to predict blowoff and flashback. The results show that, while a Damköhler number approach for blowoff is promising, important considerations are required in applying the method. For flashback, the quench constant parameter suggested for combustion induced vortex breakdown was applied and found to have limited success for predicting flashback in the present configuration.

scholarly journals Engine Testing of a Prototype Low NOx Gas Turbine Combustor

1992 ◽  
Author(s):  
Kenneth O. Smith
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbine Combustor ◽  
Operating Range ◽  
Lean Premixed ◽  
Development Goals ◽  
Engine Testing

The design of a lean-premixed, annular, dry low NOx combustor for Solar’s 5500 hp Centaur Type H gas turbine is discussed. Results from early engine tests of prototype combustion hardware are presented. The emissions results with natural gas fueling meet the development goals of less than 25 ppm NOx (at 15% O2) and 50 ppm CO. Several techniques to extend the low emissions operating range of the lean-premixed system are shown to be effective.

Flameholding Tendencies of Natural Gas and Hydrogen Flames at Gas Turbine Premixer Conditions

2014 ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
High Reliability ◽  
Elevated Pressure ◽  
Inlet Temperature ◽  
Increased Risk ◽  
Wide Range ◽  
Lean Premixed

Ground based gas turbines are responsible for generating a significant amount of electric power as well as providing mechanical power for a variety of applications. This is due to their high efficiency, high power density, high reliability, and ability to operate on a wide range of fuels. Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation. Lean-premixed operation maintains low combustion temperatures for a given turbine inlet temperature, resulting in low NOx emissions while minimizing emissions of CO and hydrocarbons. In addition, to increase overall cycle efficiency, engines are being operated at higher pressure ratios and/or higher combustor inlet temperatures. Increasing combustor inlet temperatures and pressures in combination with lean-premixed operation leads to increased reactivity of the fuel/air mixture, leading to increased risk of potentially damaging flashback. Curtailing flashback on engines operated on hydrocarbon fuels requires care in design of the premixer. Curtailing flashback becomes more challenging when fuels with reactive components such as hydrogen are considered. Such fuels are gaining interest because they can be generated from both conventional and renewable sources and can be blended with natural gas as a means for storage of renewably generated hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design one that will not anchor a flame if a flashback occurs. An experiment was constructed to determine the flameholding tendencies of various fuels on typical features found in premixer passage ways (spokes, steps, etc.) at conditions representative of a gas turbine premixer passage way. In the present work tests were conducted for natural gas and hydrogen between 3 and 9 atm, between 530 K and 650K, and free stream velocities from 40 to 100 m/s. Features considered in the present study include a spoke in the center of the channel and a step at the wall. The results are used in conjunction with existing blowoff correlations to evaluate flameholding propensity of these physical features over the range of conditions studied. The results illustrate that correlations that collapse data obtained at atmospheric pressure do not capture trends observed for spoke and wall step features at elevated pressure conditions. Also, a notable fuel compositional effect is observed.

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