Establishing Operating Limits in a Commercial Lean Premixed Combustor Operating on Synthesis Gas Pertaining to Flashback and Blowout

2012 ◽  
Author(s):  
David Page ◽  
Brendan Shaffer ◽  
Vincent McDonell
Keyword(s):  
Natural Gas ◽  
Synthesis Gas ◽  
Gas Turbines ◽  
Key Factors ◽  
High Hydrogen ◽  
Lean Blowout ◽  
Stirred Reactor ◽  
Operating Limits ◽  
The Stability ◽  
Stability Limits

Operability issues such as flashback and lean blow out are phenomena that must be addressed for successful commercial operation of stationary gas turbines. The present work focuses on flashback and lean blow out of premixed jet flames in a combustor from a commercially available gas turbine operating on synthesis gas compositions. The issue of flashback is exacerbated when operating on fuels with high hydrogen content due to the increased reactivity of hydrogen, thus increasing the propensity for flashback. Operating margins for mixtures of natural gas and carbon monoxide in hydrogen are reported. The results interestingly demonstrate reduced stability for mixtures of H2/NG than for H2/CO. Increasing H2 percentage from 0% to 100% reduced blowout equivalence ratios from Φ = 0.63 to Φ = 0.29 for H2/NG and Φ = 0.42 to Φ = 0.29 for H2/CO. In addition, results obtained for inlet temperatures of 300K and 623K are compared and show an upward shift of the stability limits for higher preheats. Modeling of the experimental data using a perfectly stirred reactor predicts the effect of the addition of H2 to natural gas on the blowout limits. With regards to flashback some key factors that dominate the characteristics are identified and attempts to correlate data are carried out. The results show that lean blowout and flashback occur at the same AFT, regardless of preheat temperatures. AFT at flashback and lean blowout are compared to a more fundamental burner [1] with results indicating reasonable scalability.

Experimental Study on Lean Blowout Limits of Turbulent Premixed Hydrogen/Ammonia/Air Mixtures

2021 ◽  
Author(s):  
Andreas Goldmann ◽  
Friedrich Dinkelacker
Keyword(s):  
Gas Turbines ◽  
Measurement Procedure ◽  
Liquid Fuels ◽  
Special Focus ◽  
Atmospheric Conditions ◽  
Ammonia Content ◽  
Lean Blowout ◽  
Combustion Properties ◽  
The Stability ◽  
Stability Limits

Abstract As the demand for greenhouse gas neutral transportation and power generation solutions is growing, alternative carbon-free fuel such as hydrogen (H2) and ammonia (NH3) are gaining more attention. Mixtures of both fuels allow the adjustment of combustion properties. With future fuels also the vision of very clean combustion can be taken into the focus, being for instance based on lean premixed and for liquid fuels prevaporized combustion for gas turbines. For the utilization of such concepts, however, flame stability is essential. In this study the upper stability limits, i.e. lean blowout of turbulent hydrogen/ammonia/air flames, is experimentally investigated in a generic non-swirl premixed burner at atmospheric conditions. Special focus is laid on a measurement setup with fully automatized measurement procedure, to reach the stability limits, as these limits tend to depend for instance on the approach speed towards the limit. The ammonia content was varied from 0 vol% to 50 vol% in 10 vol% steps with the rest being hydrogen, for a broad range of fuel-air-equivalence ratios. The lean blowout limit is increasing almost linearly with increasing fuel-air-equivalence ratios, whereas with increasing ammonia content the limit is decreasing. Furthermore, a model for the lean blowout limits were derived, which is able to predict the acquired experimental data with high accuracy.

Modeling Static Instabilities of Biogas Flames in a Stirred-Reactor Using Detailed Chemical Kinetics Simulations

2013 ◽  
Author(s):  
Christopher D. Bolin ◽  
Abraham Engeda
Keyword(s):  
Gas Turbines ◽  
Static Stability ◽  
Gas Turbine Combustor ◽  
Detailed Chemical Kinetics ◽  
Reduced Mechanism ◽  
Stirred Reactor ◽  
Primary Zone ◽  
Stability Limits ◽  
Different Sources ◽  
Detailed Chemical

Kinetic modeling of lean static stability limits of the combustion of biogas type fuels in a model of an ideal primary zone of a gas turbine combustor is presented here. In this study, CH4 is diluted with CO2 to simulate a range of gases representative of the products of anaerobic digestion of organic materials from different sources (e.g., landfill and animal waste digester). Fuels of this type are of interest for use in small gas turbines used in distributed generation applications. Predictions made by two detailed mechanisms (GRI-Mech 3.0 and San Diego) and one reduced mechanism (GRI-Mech 1.2, reduced) are employed to investigate the underlying kinetics near lean extinction. Approximate correlations to lean extinction are extracted from these results and compared to those of other fuels.

Sequential Combustion in Gas Turbines: The Key Technology for Burning High Hydrogen Contents With Low Emissions

2019 ◽  
Author(s):  
Mirko R. Bothien ◽  
Andrea Ciani ◽  
John P. Wood ◽  
Gerhard Fruechtel
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Tuning Parameter ◽  
High Hydrogen ◽  
Stable Combustion ◽  
Second Stage ◽  
In Series ◽  
Exit Temperature

Abstract Excess energy generation from renewables can be conveniently stored as hydrogen for later use as a gas turbine fuel. Also, the strategy to sequestrate CO2 from natural gas will require gas turbines to run with hydrogen-based fuels. In such scenarios, high temperature low emission combustion of hydrogen is a key requirement for the future gas turbine market. Ansaldo Energia’s gas turbines featuring sequential combustion have an intrinsic advantage when it comes to fuel flexibility and in particular hydrogen-based fuels. The sequential combustion system is composed of two complementary combustion stages in series: one premix stage followed by an auto-ignited second stage overcoming the limits of traditional premix combustion systems through a highly effective extra tuning parameter, i.e. the temperature between the first and the second stage. The standard Constant Pressure Sequential Combustion (CPSC) system as applied in the GT36 engine is tested, at high pressure, demonstrating that a modified operation concept allows stable combustion with no changes in combustor hardware for the whole range of natural gas and hydrogen blends. It is shown that in the range from 0% to 70% (vol.) hydrogen, stable combustion is achieved at full nominal exit temperature, i.e. without any derating and thus clearly outperforming other available conventional premixed combustors. Operation between 70% and 100% is possible as well and only requires a mild reduction of the combustor exit temperature. By proving the transferability of the single-can high pressure results to the engine, this paper demonstrates the practicality of operating the Ansaldo Energia GT36 H-Class gas turbine on fuels containing unprecedented concentrations of hydrogen while maintaining excellent performance and low emissions both in terms of NOx and CO2.

Flammability Limits of Low BTU Gases: Computations in a Perfectly Stirred Reactor and Experiments

2001 ◽  
Author(s):  
Fredrik Hermann ◽  
Thomas Ruck ◽  
Jens Klingmann ◽  
Fabian Mauss
Keyword(s):  
Residence Time ◽  
Gas Turbines ◽  
Thermodynamic Quantities ◽  
Flammability Limits ◽  
Gaseous Fuels ◽  
Stirred Reactor ◽  
Stability Limits ◽  
Extinction Point ◽  
Lower Heating ◽  
Made In

The demand for gas turbines suitable for Low Btu gases is increasing worldwide. This paper presents a theoretical and experimental investigation of the flammability limits of Low Btu gases for gas turbine applications. Most modern gas turbines utilize premixed combustion, making it important to know at which fuel-air ratio the flame extinguishes. The flammability limit for a gaseous fuel is a property, which is coupled to both thermodynamic quantities and the shape of the combustion chamber. Consequently, this property is characteristic for each combustor and for each fuel. The experiments were made in an atmospheric pressure premixed combustor at Alstom Power Technology Ltd. Switzerland, adapted for Low Btu gaseous fuels. Five different residual gases from chemical factories were investigated. The gases consisted of methane, carbon monoxide, hydrogen and nitrogen, with lower heating values about 2-3.5 MJ/kg for all examined gases (Table 1). A steady state Perfectly Stirred Reactor (PSR) was used as a model for the primary combustion zone. The reactions were modeled by a detailed mechanism for methane with 61 species and 667 reactions, developed by Warnatz [1]. The PSR calculations were done by decreasing the residence time until the combustion in the PSR extinguished. These calculations were repeated for different equivalence ratios to obtain the relation between the residence time and the limit of flammability. The calculations showed a relationship between the residence time in the PSR and the extinction point. It was found that the computed values of the flammability limits, or more correctly called stability limits, qualitatively follow the experimental results. However, since the computational results are strongly dependent on the residence time, a comparison with the experiments must include the residence time of the real burner, which is difficult to define.

Ash in Gas Turbines Burning Magnesium-Treated Residual Fuel

1974 ◽  
Vol 96 (2) ◽  
pp. 134-137
Author(s):  
K. W. Lay
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Graphical Method ◽  
Condensed Phases ◽  
Experimental Measurements ◽  
Ash Composition ◽  
The Stability ◽  
Magnesium Vanadates ◽  
Stability Limits

The equilibrium ash composition in a magnesium treated residual fuel-fired gas turbine is considered in detail. The stability of the condensed phases of interest—MgO, MgSO4, and the magnesium vanadates are shown to be determined by the temperature and the equilibrium SO3 pressure at the deposit. The ash present will depend on these parameters as well as the Mg : V ratio in the ash. A thermodynamic treatment of the ternary MgO-V2O5-SO3 system is presented and experimental measurements of the stability limits of Mg3V2O8 and Mg2V2O7 are presented. A simple graphical method is described for representing the condensed phases present in ash for any Mg : V ratio and for temperatures and equilibrium SO3 pressures of interest in gas turbines.

scholarly journals Air Separation Unit Integration for Alternative Fuel Projects

1998 ◽  
Author(s):  
Arthur R. Smith ◽  
Joseph Klosek ◽  
James C. Sorensen ◽  
Donald W. Woodward
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Partial Oxidation ◽  
Synthesis Gas ◽  
Gas Turbines ◽  
Low Cost ◽  
Alternative Fuel ◽  
Air Separation ◽  
Separation Unit ◽  
Integration Schemes

Alternative fuel projects often require substantial amounts of oxygen. World scale gas-to-liquids (GTL) processes based on the partial oxidation of natural gas, followed by Fischer-Tropsch chemistry and product upgrading, may require in excess of 10,000 tons per day of pressurized oxygen. The remote location of many of these proposed projects and the availability of low-cost natural gas and byproduct steam from the GTL process disadvantages the use of traditional, motor-driven air separation units in favor of steam or gas turbine drive facilities. Another process of current interest is the partial oxidation of waste materials in industrial areas to generate synthesis gas. Synthesis gas may be processed into fuels and chemicals, or combusted in gas turbines to produce electricity. A key to the economic viability of such oxygen-based processes is cost effective air separation units, and the manner in which they are integrated with the rest of the facility. Because the trade-off between capital and energy is different for the remote gas and the industrial locations, the optimum integration schemes can also differ significantly. This paper examines various methods of integrating unit operations to improve the economics of alternative fuel facilities. Integration concepts include heat recovery, as well as several uses of byproduct nitrogen to enhance gas turbine operation or power production. Start-up, control and operational aspects are presented to complete the review of integrated designs.

Gas Turbine Flexibility With Carbon Constrained Fuels

2008 ◽  
Author(s):  
Klaus Payrhuber ◽  
Robert M. Jones ◽  
Marcus H. Scholz
Keyword(s):  
Energy Conversion ◽  
Gas Turbine ◽  
Synthesis Gas ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Combined Cycle ◽  
Emissions Reduction ◽  
Hydrogen Energy ◽  
Fuel Gas ◽  
High Hydrogen

Over the next several decades, the power generation sector will face major landscape changes as CO2 management needs and hydrocarbon fuel options become limited. Uncontrolled carbon emissions from coal plants exceed natural gas fired alternatives by more than two to one due in large part to greater fuel carbon content and lower overall energy conversion efficiencies. In a carbon-constrained environment, power production from coal must realize improvements beyond incremental efficiency gains in order to have significant CO2 emissions reduction. Coal gasification and associated fuel gas process treatment units provide the mechanisms inherently needed to effectively separate carbon components on a “pre-combustion” basis, leaving essentially carbon free hydrogen fuel available for combustion within the combined cycle power plant. Gas turbines will play a significant role in meeting this generation challenge, not only from a fuel flexibility perspective, but also in the area of CO2 reduction where gas turbines will likely become the primary hydrogen energy conversion unit for the foreseeable future. Worldwide, GE gas turbines continue to demonstrate their proven, reliable performance on hydrogen bearing fuels, including installations with up to 95% hydrogen by volume. As the focus on pre-combustion carbon capture continues to grow, never has this experience with high hydrogen fuels been more relevant. Furthermore, GE continues to develop combustion designs to extend this experience to advanced gas turbine platforms, including F-class units operating on synthesis gas. The ever-present focus on efficiency improvement and emissions reduction, combined with improved gasification processes, will require future advanced combustion system designs that can achieve low emissions at higher firing temperatures with minimal to no dilution for NOx abatement. This paper discusses the challenge of low CO2 producing fuel for advanced gas turbines, firing hydrogen rich synthesis gas, in terms of gas turbine fuel and accessory system design.

scholarly journals Improvement of the turn-down ratio of gas turbines by autothermal on board syngas generation

2017 ◽  
Vol 1 ◽  
pp. D0HPA5 ◽  
Author(s):  
Max H. Baumgärtner ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Equivalence Ratio ◽  
Burning Velocity ◽  
Combined Cycle ◽  
Sudden Increase ◽  
High Hydrogen ◽  
Fuel Processor ◽  
Burn Out

Abstract The low reactivity of natural gas leads to a sudden increase of carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions below a certain load level, which limits the part load operation range of current utility gas turbines in combined cycle power plants (CCPP). The feasibility of catalytic autothermal syngas generation directly upstream of gas turbine burners to improve burn-out at low flame temperatures is studied in this paper. The adiabatic reformer is supplied with a mixture of natural gas, air and water and generates syngas with high reactivity, which results in better low-temperature combustion performance. Substitution of part of the natural gas by syngas provides the opportunity of lowering overall equivalence ratio in the combustion chamber and of extending the operation range towards lower minimum power output without violating emission limits. A generic gas turbine with a syngas generator is modelled by analytic equations to identify the possible operating window of a fuel processor constrained by pressure loss, low and high temperature limits and carbon formation. A kinetic study shows good conversion of methane to syngas with a high hydrogen share. A calculation of the one-dimensional laminar burning velocity of mixtures of syngas and methane and the assessment of the corresponding Damköhler number show the potential for lowering the minimum equivalence ratio with full burn-out by fuel processing. The study shows that such a fuel processor has a possible operating range despite the before mentioned constraints and it has potential to reduce the lowest possible load of gas turbines in terms of thermal power by 20%.

Fuel Interchangeability Effects on the Lean Blowout for a Lean Premixed Swirl Stabilized Fuel Nozzle

2018 ◽  
Author(s):  
Siddhartha Gadiraju ◽  
Suhyeon Park ◽  
Prashant Singh ◽  
Jaideep Pandit ◽  
Srinath V. Ekkad ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Fuel Blend ◽  
Lean Blowout ◽  
Fuel Blends ◽  
Lean Premixed ◽  
Combustion Technology ◽  
Fuel Nozzle

This work is motivated by an interest in understanding the fuel interchangeability of a fuel nozzle to operate under extreme lean operating conditions. A lean premixed, swirl-stabilized fuel nozzle designed with central pilot hub was used to test various fuel blends for combustion characteristics. Current gas turbine combustion technology primarily focuses on burning natural gas for industrial systems. However, interest in utilizing additional options due to environmental regulations as well as concerns about energy security have motivated interest in using fuel gases that have blends of Methane, Propane, H2, CO, CO2, and N2. For example, fuel blends of 35%/60% to 55%/35% of CH4/CO2 are typically seen in Landfill gases. Syngas fuels are typically composed primarily of H2, CO, and N2. CH4/N2 fuel blend mixtures can be derived from biomass gasification. Stringent emission requirements for gas turbines stipulate operating at extreme lean conditions, which can reduce NOx emissions. However, lean operating conditions pose the problem of potential blowout resulting in loss of performance and downtime. Therefore, it is important to understand the Lean Blowout (LBO) limits and involved mechanisms that lead to a blowout. While a significant amount of research has been performed to understand lean blowout limits and mechanisms for natural gas, research on LBO limits and mechanisms for fuel blends has only been concentrated on fuel blends of CH4 and H2 such as syngas. This paper studies the lean blowout limits with fuel blends CH4-C3H8, CH4-CO2, and CH4-N2 and also their effect on the stability limits as the pilot fuel percentage was varied. Experimental results demonstrate that the addition of propane, nitrogen and carbon dioxide has minimal effect on the adiabatic flame temperature when the flame becomes unstable under lean operating conditions. On the other hand, the addition of diluent gas showed a potential blowout at higher adiabatic temperatures.

CFD Modelling of Biogas Cofiring in a Gas Turbine

2002 ◽  
Author(s):  
J. A. Lycklama a` Nijeholt ◽  
E. M. J. Komen ◽  
R. T. E. Hermanns ◽  
L. P. H. de Goey ◽  
M. C. van Beek ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Burning Velocity ◽  
Combustion Process ◽  
Combustion Model ◽  
Cfd Modelling ◽  
Combustion Chemistry ◽  
Feasible Option ◽  
Safe Limit ◽  
The Stability

Cofiring of biogas in existing gas turbines is a feasible option to reduce the consumption of natural gas. However, admixing of biogas will have an effect on the combustion process. As a consequence, the burning velocity and, therefore, the flame stability may be affected when a significant amount of biogas is mixed with the natural gas. The effect of admixing natural gas with biogas on the stability of the combustion process in lean premixed gas turbines is insufficiently known. In the present paper, a Computational Fluid Dynamics (CFD) methodology will be presented for the assessment of the safe limit of biogas cofiring in a gasturbine. An advanced Flamelet/Flamefront combustion model [1, 2, 3] and the Coherent Flame Model [4] are utilized. In both models, the detailed GRI 3.0 reaction mechanism [5] has been used to describe the combustion chemistry. The degree of mixing of fuel and air in the lean premix-burners of the gasturbine has been determined with a separate CFD model of the burners.

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