Lean Blowout Limit and NOx Production of a Premixed Sub-ppm NOx Burner With Periodic Recirculation of Combustion Products

2004 ◽  
Vol 128 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Jochen R. Kalb ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Flue Gas ◽  
Combustion Products ◽  
Gas Content ◽  
Stable Operation ◽  
Reacting Flow ◽  
Nox Emissions ◽  
Current Standard ◽  
Lean Blowout ◽  
Fresh Mixture

The technological objective of this work is the development of a lean-premixed burner for natural gas. Sub-ppm NOx emissions can be accomplished by shifting the lean blowout limit (LBO) to slightly lower adiabatic flame temperatures than the LBO of current standard burners. This can be achieved with a novel burner concept utilizing spatially periodic recirculation of combustion products: Hot combustion products are admixed to the injected premixed fresh mixture with a mass flow rate of comparable magnitude, in order to achieve self-ignition. The subsequent combustion of the diluted mixture again delivers products. A fraction of these combustion products is then admixed to the next stream of fresh mixture. This process pattern is to be continued in a cyclically closed topology, in order to achieve stable combustion of, for example, natural gas in a temperature regime of very low NOx production. The principal ignition behavior and NOx production characteristics of one sequence of the periodic process was modeled by an idealized adiabatic system with instantaneous admixture of partially or completely burnt combustion products to one stream of fresh reactants. With the CHEMKIN-II package, a reactor network consisting of one perfectly stirred reactor (PSR, providing ignition in the first place) and two plug flow reactors (PFR) has been used. The effect of varying burnout and the influence of the fraction of admixed flue gas has been evaluated. The simulations have been conducted with the reaction mechanism of Miller and Bowman and the GRI-Mech 3.0 mechanism. The results show that the high radical content of partially combusted products leads to a massive decrease of the time required for the formation of the radical pool. As a consequence, self-ignition times of 1 ms are achieved even at adiabatic flame temperatures of 1600 K and less, if the flue gas content is about 50–60% of the reacting flow after mixing is complete. Interestingly, the effect of radicals on ignition is strong, outweighs the temperature deficiency and thus allows stable operation at very low NOx emissions.

Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm NOx Burner With Periodic Flue Gas Recirculation

2004 ◽  
Author(s):  
Jochen R. Kalb ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Flue Gas ◽  
Gas Content ◽  
Stable Operation ◽  
Reacting Flow ◽  
Nox Emissions ◽  
Lean Blowout ◽  
Fresh Mixture ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

The technological objective of this work is the development of a lean-premixed burner for natural gas. Sub-ppm NOx emissions can be accomplished by shifting the lean blowout limit (LBO) to slightly lower adiabatic flame temperatures than the LBO of current standard burners. This can be achieved with a novel burner concept utilizing periodic flue gas recirculation: Hot flue gas is admixed to the injected premixed fresh mixture with a mass flow rate of comparable magnitude, in order to achieve self-ignition. The subsequent combustion of the diluted mixture again delivers flue gas. A fraction of the combustion products is then admixed to the next stream of fresh mixture. This process pattern is to be continued in a cyclically closed topology, in order to achieve stable combustion of e.g. natural gas in a temperature regime of very low NOx production. The principal ignition behavior and NOx production characteristics of one sequence of the periodic process was modeled by an idealized adiabatic system with instantaneous admixture of partially or completely burnt flue gas to one stream of fresh reactants. With the CHEMKIN-II package a reactor network consisting of one perfectly stirred reactor (PSR, providing ignition in the first place) and two plug flow reactors (PFR) has been used. The effect of varying burnout and the influence of the fraction of admixed flue gas have been evaluated. The simulations have been conducted with the reaction mechanism of Miller and Bowman and the GRI-Mech 3.0 mechanism. The results show that the high radical content of partially combusted products leads to a massive decrease of the time required for the formation of the radical pool. As a consequence, self-ignition times of 1 ms are achieved even at adiabatic flame temperatures of 1600 K and less, if the flue gas content is about 50%–60% of the reacting flow after mixing is complete. Interestingly, the effect of radicals on ignition is strong, outweighs the temperature deficiency and thus allows stable operation at very low NOx emissions.

Emission Characteristics of a Premixed Cyclic-Periodical-Mixing Combustor Operated With Hydrogen-Natural Gas Fuel Mixtures

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Jochen R. Brückner-Kalb ◽  
Michael Krösser ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Combustion Process ◽  
Chemical Reactor ◽  
Combustion Products ◽  
Chemical Effect ◽  
Nox Emissions ◽  
Nox Formation ◽  
Lean Blowout ◽  
Asme Turbo Expo

The concept of the cyclic periodical mixing combustion process (Kalb, and Sattelmayer, 2004, “Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm-NOx Burner With Periodic Flue Gas Recirculation,” Proceedings of the ASME Turbo Expo 2004, Paper No. GT2004-53410; Kalb, and Sattelmayer, 2006, “Lean Blowout Limit and NOx-Production of a Premixed Sub-ppm-NOx Burner With Periodic Recirculation of Combustion Products,” ASME J. Eng. Gas Turbines Power, 128(2), pp. 247–254) for the extension of the lean blowout limit had been implemented in an atmospheric experimental combustor for testing with both external perfect (Brückner-Kalb, Hirsch, and Sattelmayer, 2006, “Operation Characteristics of a Premixed Sub-ppm NOx Burner With Periodical Recirculation of Combustion Products,” Proceedings of the ASME Turbo Expo 2006, Paper No. GT2006-90072) and technical (Brückner-Kalb, Napravnik, Hirsch, and Sattelmayer, 2007, “Development of a Fuel-Air Premixer for a Sub-ppm NOx Burner,” Proceedings of the ASME Turbo Expo 2007, Paper No. GT2007-27779) premixing of reactants. It had been tested with natural gas and has now been tested with a mixture of 70%vol of hydrogen and 30%vol of natural gas (98% CH4) as fuel. With natural gas the NOx emissions are unaffected by the limited technical premixing quality, as long as the air preheat is in the design range of the premixers (Brückner-Kalb, Napravnik, Hirsch, and Sattelmayer, 2007, “Development of a Fuel-Air Premixer for a Sub-ppm NOx Burner,” Proceedings of the ASME Turbo Expo 2007, Paper No. GT2007-27779). Then, for adiabatic flame temperatures of up to 1630 K NOx emissions are below 1 ppm(v) with CO emissions below 8 ppm(v) in the whole operation range of the test combustor (15% O2, dry). With the “70%volH2−30%volCH4” mixture the NOx emissions increase by nearly one order of magnitude. Then, NOx emissions below 7 ppm(v) (15% O2, dry) are achieved for adiabatic flame temperatures of up to 1600 K. They approach the 1 ppm(v) level only for flame temperatures below 1450 K. CO emissions are below 4 ppm(v). The reason for the increase in the NOx emissions is the higher reactivity of the mixture, which leads to earlier ignition in zones of still elevated unmixedness of reactants near the premixer-injector exits. This effect was investigated by chemical reactor network simulations analyzing a pressure effect and an additional chemical effect of hydrogen combustion on NOx formation.

Hydrogen Enriched Combustion Testing of SIEMENS Industrial SGT-400 at Atmospheric Conditions

2014 ◽  
Author(s):  
Kam-Kei Lam ◽  
Philipp Geipel ◽  
Jenny Larfeldt
Keyword(s):  
Pressure Drop ◽  
Natural Gas ◽  
High Speed ◽  
Flame Temperature ◽  
Stable Operation ◽  
Nox Emissions ◽  
Atmospheric Conditions ◽  
Reference Velocity ◽  
Operation Conditions ◽  
Combustion Behaviors

In order to further extend the turbine fuel flex capability, a test under atmospheric conditions of a full-scale SGT-400 burner was performed to study the combustion behavior when operating on hydrogen enriched natural gas. A high speed camera was installed in the rig to investigate the flame dynamics on different operation conditions. NOx emissions were measured for all presented conditions. The combustion system was instrumented with thermocouples on all the key locations to allow flame position monitoring and to avoid flame attachment on the hardware. Further measurements included static pressure probes to monitor combustor pressure drop. The test was conducted in a systematic matrix format to include the most important combustion parameters in order to identify their individual effects on the combustion behaviors. The quantity of hydrogen in natural gas, fuel split, air preheat temperature, air reference velocity and flame temperature were the combustion related variables studied in the presented test campaign. The volumetric hydrogen quantity could be increased to 30% maintaining stable operation for all measured conditions. Higher hydrogen contents up to 80 vol-% were reached without flash back tendency. A glowing spark igniter prevented testing at even higher hydrogen contents. Hydrogen enriched gas showed higher NOx emissions and improved blowout limit. Hydrogen blending in the fuel also reduced the combustor pressure drop, lowered the prechamber temperature and raised the pilot tip temperature.

Evaluation of Gas Turbine Combustors Running on Renewable Fuels Produced From Carbon Dioxide Aimed for Greenhouse Emission Reduction

2021 ◽  
Author(s):  
B. Chudnovsky ◽  
I. Chatskiy ◽  
A. Lazebnikov
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Flue Gas ◽  
Emission Reduction ◽  
Nox Reduction ◽  
Renewable Fuels ◽  
Nox Emissions ◽  
Co2 Emission Reduction ◽  
Water Steam ◽  
Carbon Neutrality

Abstract Over the past decades there has been a dramatic increase in natural gas burning as the benign fossil fuel, offering far lower emissions than oil or coal. Its place had been established in a clean, or at least, cleaner energy future. Today, the national and international energy policy has been shifted to carbon neutrality — achieving net zero carbon emissions — and as result has moved natural gas from the “benign” to the “menace” category At present, there are chiefly two alternatives for fuel carbon neutrality under discussion: power-to-gas (PtG) producing methane (or synthetic natural gas, SNG, hydrogen etc.) and power-to-liquid, which stores electric power in the form of methanol. In opposite to other synthetic or fossil fuels, like synthetic methane, NG or hydrogen, methanol burning leads to significant reductions in emissions of nitrogen oxides without any substantial firing system design change. Burning of synthetic methane or hydrogen requires significant effort for NOx reduction. Hydrogen as a fuel offers many advantages in power production. It is a carbon-free fuel that can decarbonize power and heat generation, and transportation, to help meet long-term CO2 emission-reduction targets. However, things are different for NOx emissions are a different matter. The more hydrogen is added to a NG, the higher the NOx is anticipated. Dry Low NOx (DLN) combustor has traditionally mixed NG with sufficient air upstream the combustor, so burning can take place in a lean atmosphere to maintain a relatively cool flame and thus keep NOx down. That approach does not work so well when more hydrogen enters the picture due to auto ignition occurring in the premix zone. Some companies already have diffusion-type combustor technology where fuel and air are supplied separately. Combustion of hydrogen, specifically in diffusion mode, implies combustion with a hotter flame, leading to higher combustion temperatures and the formation of local hot spots. These, in turn, can cause NOx to increase. The generalized solution is to cool the flame using diluents, such as demineralized water, steam or nitrogen. However, reducing NOx, by dilution reduces efficiency compared to a DLN combustor. Another option of providing wide load range of GT operation, while maintaining low NOx emissions is fuel dilution with flue gas being recirculated from the exhaust (FGR - Flue gas recirculation). The present paper discusses the effect of burning renewable fuels produced from carbon dioxide and hydrogen which are being diluted with a flow of FGR on GT performance and emissions reduction in diffusion combustors. For the prediction of the combustion behavior a methodology that combines experimental work and computational simulations was used. Given the fact that due to the increase in renewable energy introduction into the grid, addition of renewable fuel-based energy produced from carbon dioxide becomes very significant. Hence, the development of enhanced firing systems burning synthetic clean fuels with low emissions is challenging and should be promoted. Using renewable fuels for energy supply would reduce the unfavorable impact of CO2 and allow meeting the targets established in the Kyoto and Paris Protocols.

Emission Characteristics of a Premixed Cyclic-Periodical-Mixing Combustor Operated With Hydrogen-Natural Gas Fuel Mixtures

2008 ◽  
Author(s):  
Jochen R. Bru¨ckner-Kalb ◽  
Michael Kro¨sser ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Chemical Reactor ◽  
Chemical Effect ◽  
Nox Emissions ◽  
Nox Formation ◽  
Lean Blowout ◽  
Order Of Magnitude ◽  
Network Simulations ◽  
Fuel Mixtures

The concept of the cyclic periodical mixing combustion process (CPMCP) [1, 2] for the extension of the lean blowout limit had been implemented in an atmospheric experimental combustor for testing with both external perfect [3] and technical [4] premixing of reactants. It had been tested with natural gas and has now been tested with a mixture of 70%Vol of hydrogen and 30%Vol of natural gas (98% CH4) as fuel. With natural gas the NOx emissions are unaffected by the limited technical premixing quality, as long as the air preheat is in the design range of the premixers [4]. Then, for adiabatic flame temperatures of up to 1630 K NOx emissions are below 1 ppm(v) with CO emissions below 8 ppm(v) in the whole operation range of the test combustor (15% O2, dry). With the “70%Vol H2 – 30%Vol CH4” mixture the NOx emissions increase by nearly one order of magnitude. Then, NOx emissions below 7 ppm(v) (15% O2, dry) are achieved for adiabatic flame temperatures of up to 1600 K. They approach the 1 ppm(v) level only for flame temperatures below 1450 K. CO emissions are below 4 ppm(v). The reason for the increase of the NOx emissions is the higher reactivity of the mixture, which leads to earlier ignition in zones of still elevated unmixedness of reactants near the premixer-injector exits. This effect was investigated by chemical reactor network simulations, analyzing a pressure effect and an additional chemical effect of hydrogen combustion on NOx formation.

Firing Trials of the Siemens SGT-300 Dry Low Emissions Combustion System Using High Calorific Value Fuels

2020 ◽  
Author(s):  
Kristopher Calladine ◽  
Jim Rogerson ◽  
Phill Hubbard ◽  
Suresh K. Sadasivuni ◽  
Ghenadie Bulat
Keyword(s):  
Natural Gas ◽  
Calorific Value ◽  
Nox Emissions ◽  
Combustion System ◽  
Industrial Emissions ◽  
Current Standard ◽  
Load Range ◽  
Heavy Fuel Oils ◽  
Wobbe Index ◽  
Industrial Gas Turbine

Abstract The current paper presents an extension of the fuel flexibility of the Siemens SGT-300 Dry Low Emissions combustion system to include High Calorific Value fuels, achieved using the engine’s current standard combustion hardware. Results from high pressure rig tests show that the standard SGT-300 DLE combustor can reliably operate on High Calorific Value fuels with temperature corrected Wobbe Index up to 63MJ/m3, which corresponds to Grade A LPG (60%vol. C3H8, 40%vol. C4H10). Metal temperatures of the combustion hardware when operating on High Calorific Value fuels are within life acceptance criteria for the Siemens SGT-300 industrial gas turbine. NOx emissions throughout the load range of the engine comply with the EU Industrial Emissions Directive. At part load, a reduced requirement for piloting compared to Natural Gas yields relatively low temperatures at the burner face and low NOx emissions. NOx emissions at full load, which tend to increase with increasing heating value, are higher than for Natural Gas but lower than for diesel and heavy fuel oils.

Study on the Basic Characteristics of Low Oxygen Air Combustion with Natural Gas in Glass Tempering Furnace

2014 ◽  
Vol 672-674 ◽  
pp. 1510-1513
Author(s):  
Jia Qun Xia ◽  
Guang Hui Liu ◽  
Yu Si Wang ◽  
Hu Ping Li
Keyword(s):  
Heat Transfer ◽  
Natural Gas ◽  
Flue Gas ◽  
Radiation Heat Transfer ◽  
Combustion Products ◽  
Gas Composition ◽  
Low Oxygen ◽  
Radiation Heat ◽  
Excess Air ◽  
Basic Characteristics

The basic characteristics of natural gas with low oxygen air combustion is analyzed, and low oxygen content, excess air ratio, and the change of flue gas composition are studied, the results show that using the technology of low oxygen air combustion for glass tempering furnace in production has directive significance. The composition content of carbon dioxide and water vapor increases in the combustion products. The radiation heat transfer is decreased in glass tempering furnace. The furnace temperatures are maintained in the range of 650 to 800°C.

scholarly journals On the Impacts of Pre-Heated Natural Gas Injection in Blast Furnaces

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 771 ◽  
Author(s):  
Tyamo Okosun ◽  
Samuel Nielson ◽  
John D’Alessio ◽  
Shamik Ray ◽  
Stuart Street ◽  
...  
Keyword(s):  
Natural Gas ◽  
Low Cost ◽  
Injection Rate ◽  
High Rate ◽  
Injection Velocity ◽  
Stable Operation ◽  
Reacting Flow ◽  
Blast Furnaces ◽  
Gas Combustion ◽  
Quenching Effect

During recent years, there has been great interest in exploring the potential for high-rate natural gas (NG) injection in North American blast furnaces (BFs) due to the fuel’s relatively low cost, operational advantages, and reduced carbon footprint. However, it is well documented that increasing NG injection rates results in declining raceway flame temperatures (a quenching effect on the furnace, so to speak), with the end result of a functional limit on the maximum injection rate that can be used while maintaining stable operation. Computational fluid dynamics (CFD) models of the BF raceway and shaft regions developed by Purdue University Northwest’s (PNW) Center for Innovation through Visualization and Simulation (CIVS) have been applied to simulate multi-phase reacting flow in industry blast furnaces with the aim of exploring the use of pre-heated NG as a method of widening the BF operating window. Simulations predicted that pre-heated NG injection could increase the flow of sensible heat into the BF and promote complete gas combustion through increased injection velocity and improved turbulent mixing. Modeling also indicated that the quenching effects of a 15% increase in NG injection rate could be countered by a 300K NG pre-heat. This scenario maintained furnace raceway flame temperatures and top gas temperatures at levels similar to those observed in baseline (stable) operation, while reducing coke rate by 6.3%.

Operation Characteristics of a Premixed Sub-ppm NOx Burner With Periodical Recirculation of Combustion Products

2006 ◽  
Author(s):  
Jochen R. Bru¨ckner-Kalb ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Pressure Drop ◽  
Thermodynamic Equilibrium ◽  
Atmospheric Pressure ◽  
Combustion Process ◽  
Combustion Products ◽  
Low Pressure ◽  
Nox Emissions ◽  
Lean Blowout ◽  
Stable Combustion ◽  
Operation Characteristics

The concept of the periodic mixing and combustion process, which has been presented earlier [1,2], has been implemented in a nearly adiabatic combustor for investigations at atmospheric pressure. The objective of this combustion process is to achieve stable combustion at adiabatic flame temperatures being considerably lower than the lean blowout temperature of aerodynamically stabilized flames with low pressure drop in the combustor in order to reduce NOx emissions and to achieve CO emissions near the thermodynamic equilibrium. For preheat temperatures between 390 K and 790 K, the periodic mixing combustor can be operated near the lean blowout limit with adiabatic flame temperatures down to 1510 K – 1600 K. The test combustor yields over the entire operation range of 1:4 (thermal powers from 47 kW up to 175 kW) very low emissions of NOx below 1 ppm(v) (15% O2, dry) and of CO below 8 ppm(v).

Development and Operation of a Pressurized Optically-Accessible Research Combustor for Simulation Validation and Fuel Variability Studies

2005 ◽  
Author(s):  
T. Sidwell ◽  
K. Casleton ◽  
D. Straub ◽  
D. Maloney ◽  
G. Richards ◽  
...  
Keyword(s):  
Natural Gas ◽  
Boundary Conditions ◽  
Experimental Testing ◽  
Flame Temperature ◽  
Heat Losses ◽  
Department Of Energy ◽  
Stable Operation ◽  
Pure Hydrogen ◽  
Nox Emissions ◽  
Combustion Dynamics

The U.S. Department of Energy Turbines Program has established very stringent NOx emissions goals of less than 3 ppmv for future turbine power generation. These future turbine power plants may operate on hydrogen-rich fuels, such as coal-derived synthesis gas (syngas), or pure hydrogen derived from shifting the syngas. Achieving these goals is expected to require improved combustor concepts which may be dramatically different than current combustor designs. Significant and costly experimental testing is usually required to assess new combustor concepts. Ideally, new concepts could be evaluated with numeric simulations to reduce development time and cost. However, current simulation capabilities are not sufficient to reliably capture the effects of fuel variations on flame extinction, emissions levels, and dynamic stability. Furthermore, very little data with controlled boundary conditions are available to check numeric predictions at actual turbine engine conditions, or simply to assess combustor performance without ambiguous boundary conditions. This paper presents a description of the development and operation of an optically-accessible research combustor, which is designed to provide fundamental combustion data at elevated pressure and inlet air temperature, and with precisely determined thermal, acoustic, and flow boundary conditions. The effects of fuel composition variations are investigated by blending of controlled quantities of hydrogen with natural gas. Recent test results — emissions data, dynamics data, and heat losses for hydrogen addition from 0 to 40% by fuel volume at two combustor pressures — and a description of future testing are also presented. The results show that the addition of hydrogen to natural gas in percentages as low as 5% of total fuel volume can significantly decrease the lean extinction limit, and promote stable operation at lower equivalence ratios while promoting lower NOx emissions. Dynamic pressures were measured, but combustion dynamics were not present due to the combustor configuration. The effect of heat losses on flame temperature and emissions were quantified.

Sign in / Sign up

Export Citation Format

Share Document