Characterization of a Real Size Retrofittable Catalytic Combustion System

2008 ◽  
Author(s):  
Olaf Diers ◽  
Michael Fischer ◽  
Johannes Heinze ◽  
Johan Koopman ◽  
Denis Schneider ◽  
...  
Keyword(s):  
Nox Reduction ◽  
Gas Analysis ◽  
Flame Stabilization ◽  
Catalytic Reactor ◽  
Atmospheric Conditions ◽  
Reactor Model ◽  
Nox Formation ◽  
Radial Temperature ◽  
Stirred Reactor ◽  
Anti Stokes

This contribution describes the investigation of an engine-scale catalytic hybrid burner. The burner has been investigated under atmospheric conditions with preheated air and natural gas fuel in two operating points, with and without the catalytic reactor. By using the catalyst, an extension of the operating range to leaner stoichiometries has been demonstrated. Exhaust gas analysis performed directly downstream of the burner as well as in the burner far-field showed a NOx reduction potential of more than 20% when employing the catalyst. For the operation with the catalytic reactor, the flame stabilization process and dependency of NOx formation on the piloting gas ratio is described with results of OH chemiluminescence measurements. Radial temperature profiles taken with Coherent Anti Stokes Raman Scattering (CARS) suggest a reaction delay directly downstream of the catalytic section of the burner. Calculations with a perfectly stirred reactor model help to obtain a better understanding of the kinetics of the hot gases leaving the catalyst section.

A Reactor Model for the NOx Formation in a Reacting Jet in Hot Cross Flow Under Atmospheric and High Pressure Conditions

2014 ◽  
Author(s):  
Vera Hoferichter ◽  
Denise Ahrens ◽  
Michael Kolb ◽  
Thomas Sattelmayer
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Nox Reduction ◽  
Cross Flow ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Ignition Process ◽  
Reactor Model ◽  
Nox Formation

Staged combustion is a promising technology for gas turbines to achieve load flexibility and low NOx emission levels at the same time. Therefore, a large scale atmospheric test rig has been set up at the Institute of Thermodynamics, Technical University of Munich to study NOx emission characteristics of a reacting jet in hot cross flow. The premixed primary combustion stage is operated at ϕ = 0.5 and provides the hot cross flow. In the second stage a premixed jet at ϕ = 0.77 is injected perpendicular to the first stage. In both stages natural gas is used as fuel and air as oxidant. This paper presents a reactor model approach for the computation of the resulting NOx concentrations. The mixing and ignition process along the jet streamline of maximum NOx formation is simulated using a perfectly stirred reactor with Cantera 1.8. The reactor model is validated for the ambient pressure case using experimental data. Afterwards, a high pressure simulation is performed in order to investigate the NOx emission characteristics under gas turbine conditions. The NOx formation is divided into flame NOx and post flame NOx. The reactor model reveals that the formation of post flame NOx in the second combustion stage can be efficiently suppressed due to fast mixing with cross flow material and the corresponding temperature reduction. Compared to single stage combustion with the same power output, no NOx reduction was observed in the experiment. However, the results from the reactor model suggest a NOx reduction potential at gas turbine conditions caused by the increased influence of post flame NOx production at high pressure.

scholarly journals Characterization of NOx, N2O, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor

1996 ◽  
Author(s):  
Robert C. Steele ◽  
Jon H. Tonouchi ◽  
David G. Nicol ◽  
David C. Horning ◽  
Philip C. Malte ◽  
...  
Keyword(s):  
High Pressure ◽  
Computational Models ◽  
Chemical Reactor ◽  
Reactor Model ◽  
N2o Formation ◽  
Nox Formation ◽  
Lean Premixed Combustion ◽  
Stirred Reactor ◽  
Lean Premixed ◽  
In Series

A high-pressure jet-stirred reactor (HP-JSR) has been built and applied to the study of NOx and N2O formation and CO oxidation in lean-premixed (LPM) combustion. The measurements obtained with the HP-JSR provide information on how NOx forms in lean-premixed, high-intensity combustion, and provide comparison to NOx data published recently for practical LPM combustors. The HP-JSR results indicate that the NOx yield is significantly influenced by the rate of relaxation of super-equilibrium concentrations of the O-atom. Also indicated by the HP-JSR results are characteristic NOx formation rates. Two computational models are used to simulate the HP-JSR, and to provide comparison to the measurements. The first is a chemical reactor model (CRM) consisting of two perfectly-stirred reactors (PSRs) placed in series. The second is a stirred reactor model with finite rate macromixing (i.e., recirculation) and micromixing. The micromixing is treated by either coalescence-dispersion (CD) or interaction-by-exchange-with-the-mean (IEM) theory. Additionally, a model based on one-dimensional gas dynamics with chemical reaction is used to assess chemical conversions within the gas sample probe.

Characterization of NOx, N20, and CO for Lean-Premixed Combustion in a High-Pressure Jet-Stirred Reactor

1998 ◽  
Vol 120 (2) ◽  
pp. 303-310 ◽  
Author(s):  
R. C. Steele ◽  
J. H. Tonouchi ◽  
D. G. Nicol ◽  
D. C. Horning ◽  
P. C. Malte ◽  
...  
Keyword(s):  
High Pressure ◽  
Computational Models ◽  
Chemical Reactor ◽  
Reactor Model ◽  
N2o Formation ◽  
Nox Formation ◽  
Lean Premixed Combustion ◽  
Stirred Reactor ◽  
Lean Premixed ◽  
In Series

A high-pressure jet-stirred reactor (HP-JSR) has been built and applied to the study of NOx and N2o formation and CO oxidation in lean-Premixed (LPM) combustion. The measurements obtained with the HP-JSR Provide information on how NOx forms in lean-premixed, high-intensity combustion, and provide comparison to NOx data published recently for practical LPM combustors. The HP-JSR results indicate that the NOx yield is significantly influenced by the rate of relaxation of super-equilibrium concentrations of the O-atom. Also indicated by the HP-JSR results are characteristic NOx formation rates. Two computational models are used to simulate the HP-JSR and to provide comparison to the measurements. The first is a chemical reactor model (CRM) consisting of two perfectly stirred reactors (PSRs) placed in series. The second is a stirred reactor model with finite rate macromixing (i.e., recirculation) and micromixing. The micromixing is treated by either coalescence-dispersion (CD) or interaction by exchange with the mean (IEM) theory. Additionally, a model based on one-dimensional gas dynamics with chemical reaction is used to assess chemical conversions within the gas sample probe.

NOx Reduction Strategy by Staged Combustion with Plasma-Assisted Flame Stabilization

2012 ◽  
Vol 26 (7) ◽  
pp. 4284-4290 ◽  
Author(s):  
Dae Hoon Lee ◽  
Kwan-Tae Kim ◽  
Hee Seok Kang ◽  
Young-Hoon Song ◽  
Jae Eon Park
Keyword(s):  
Nox Reduction ◽  
Flame Stabilization ◽  
Staged Combustion ◽  
Reduction Strategy

A Multidisciplinary Approach for the Comprehensive Assessment of Integrated Rotorcraft–Powerplant Systems at Mission Level

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Ioannis Goulos ◽  
Fakhre Ali ◽  
Konstantinos Tzanidakis ◽  
Vassilios Pachidis ◽  
Roberto d'Ippolito
Keyword(s):  
Environmental Impact ◽  
Fuel Consumption ◽  
Comprehensive Assessment ◽  
Pollutant Emissions ◽  
Operational Performance ◽  
Civil Aviation ◽  
Accurate Estimation ◽  
Nox Emissions ◽  
Reactor Model ◽  
Stirred Reactor

This paper presents an integrated methodology for the comprehensive assessment of combined rotorcraft–powerplant systems at mission level. Analytical evaluation of existing and conceptual designs is carried out in terms of operational performance and environmental impact. The proposed approach comprises a wide-range of individual modeling theories applicable to rotorcraft flight dynamics and gas turbine engine performance. A novel, physics-based, stirred reactor model is employed for the rapid estimation of nitrogen oxides (NOx) emissions. The individual mathematical models are implemented within an elaborate numerical procedure, solving for total mission fuel consumption and associated pollutant emissions. The combined approach is applied to the comprehensive analysis of a reference twin-engine light (TEL) aircraft modeled after the Eurocopter Bo 105 helicopter, operating on representative mission scenarios. Extensive comparisons with flight test data are carried out and presented in terms of main rotor trim control angles and power requirements, along with general flight performance charts including payload-range diagrams. Predictions of total mission fuel consumption and NOx emissions are compared with estimated values provided by the Swiss Federal Office of Civil Aviation (FOCA). Good agreement is exhibited between predictions made with the physics-based stirred reactor model and experimentally measured values of NOx emission indices. The obtained results suggest that the production rates of NOx pollutant emissions are predominantly influenced by the behavior of total air inlet pressure upstream of the combustion chamber, which is affected by the employed operational procedures and the time-dependent all-up mass (AUM) of the aircraft. It is demonstrated that accurate estimation of on-board fuel supplies ahead of flight is key to improving fuel economy as well as reducing environmental impact. The proposed methodology essentially constitutes an enabling technology for the comprehensive assessment of existing and conceptual rotorcraft–powerplant systems, in terms of operational performance and environmental impact.

Bench Scale Testing of Low-NOx LBG Combustors

1982 ◽  
Vol 104 (1) ◽  
pp. 120-128 ◽  
Author(s):  
W. D. Clark ◽  
B. A. Folsom ◽  
W. R. Seeker ◽  
C. W. Courtney
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Attractive Alternative ◽  
Nox Emissions ◽  
Catalytic Reactor ◽  
Power Cycle ◽  
Bench Scale ◽  
Gasification Process ◽  
Stirred Reactor ◽  
Catalytic Reformer

The high efficiencies obtained in a combined gas-turbine/steam-turbine power cycle burning low Btu gas (LBG) make it a potentially attractive alternative to the high sulfur emitting direct coal-fired steam cycle. In the gasification process, much of the bound nitrogen in coal is converted to ammonia in the LBG. This ammonia is largely converted to nitrogen oxides (NOx) in conventional combustors. This paper examines the pressurized bench scale performance of reactors previously demonstrated to produce low NOx emissions in atmospheric laboratory scale experiments. LBG was synthesized in a catalytic reformer and fired in three reactors: a catalytic reactor, a diffusion flame, and a stirred reactor. Effects of scale, pressure, stoichiometry, residence time, and preheat were examined. Lowest NOx emissions were produced in a rich/lean series staged catalytic reactor.

NOx Emissions in a Steel Reheat Furnace Firing By-Product Fuels

2001 ◽  
Author(s):  
Bradley R. Adams ◽  
Dave H. Wang
Keyword(s):  
Low Cost ◽  
Nox Reduction ◽  
Coke Oven ◽  
Cfd Modeling ◽  
Stoichiometric Ratio ◽  
Nox Emissions ◽  
Confined Space ◽  
Nox Formation ◽  
Reheat Furnace ◽  
Bottom Zone

Abstract A DOE-funded program was used to understand the mechanisms that control the formation of NOx during the combustion of steelmaking by-product fuels and to investigate possible low-cost control options to minimize the NOx emissions. This paper discusses the CFD modeling results of NOx emissions in a reheat furnace. The reheat furnace has a total of 20 burners distributed over three firing zones. The furnace is fired at a rate of 250 × 106 Btu/hr and an overall stoichiometric ratio of 1.06 (fuel lean). Fuels with heating values of approximate 500 Btu/SCF were examined, including coke oven gas (COG), blast furnace gas (BFG) and a blend of COG, BFG, natural gas (NG) and nitrogen. A good range of process variables was modeled to examine effects of fuel type, air preheat, stoichiometric ratio, firing rate and burner stoichiometry distribution on NOx emissions. Modeling results indicated that NOx formation in the reheat furnace is dominated by thermal NO, with some variation depending on the fuel fired. Temperature profiles showed an effective separation of the furnace interior into top and bottom zones as a result of the steel slab barrier. Higher temperatures characterized the bottom zone and elevated NOx levels as a result of the confined space and enhanced fuel air mixing provided by the slab supports. Results also showed that reburning of NOx plays a significant role in final NOx emissions with 30–40% of NOx formed being reduced by reburning in most cases. Modeling identified that operating the side burners in each burner zone slightly substoichiometric (while maintaining the overall furnace stoichiometry at 1.06) provided significant NOx reduction via reburning. NOx reductions of 23% and 30% were predicted when firing with COG and COG-NG-Air fuels, respectively. Overall furnace exit temperatures and heat flux profiles were not significantly affected by the biased firing.

Lowering Equivalence Ratio Limit for Stable Combustion in Gas Turbines by Injection of Free Radicals

2011 ◽  
Author(s):  
Yeshayahou Levy ◽  
Vladimir Erenburg ◽  
Valery Sherbaum ◽  
Vitali Ovcharenko ◽  
Leonid Rosentsvit ◽  
...  
Keyword(s):  
Free Radicals ◽  
Gas Turbines ◽  
Equivalence Ratio ◽  
Nox Reduction ◽  
Combustion Process ◽  
Combustion Regime ◽  
Combustion Stability ◽  
Nox Formation ◽  
Stable Combustion ◽  
Lean Premixed

Lean premixed combustion is one of the widely used methods for NOx reduction in gas turbines (GT). When this method is used combustion takes place under low Equivalence Ratio (ER) and at relatively low combustion temperature. While reducing temperature decreases NOx formation, lowering temperature reduces the reaction rate of the hydrocarbon–oxygen reactions and deteriorates combustion stability. The objective of the present work was to study the possibility to decrease the lower limit of the stable combustion regime by the injection of free radicals into the combustion zone. A lean premixed gaseous combustor was designed to include a circumferential concentric pilot flame. The pilot combustor operates under rich fuel to air ratio, therefore it generates a significant amount of reactive radicals. The experiments as well as CFD and CHEMKIN simulations showed that despite of the high temperatures obtained in the vicinity of the pilot ring, the radicals’ injection from the pilot combustor has the potential to lower the limit of the global ER (and temperatures) while maintaining stable combustion. Spectrometric measurements along the combustor showed that the fuel-rich pilot flame generates free radicals that augment combustion stability. In order to study the relevant mechanisms responsible for combustion stabilization, CHEMKIN simulations were performed. The developed chemical network model took into account some of the basic parameters of the combustion process: ER, residence time, and the distribution of the reactances along the combustor. The CHEMKIN simulations showed satisfactory agreement with experimental results.

Coherent Flame Model to Predict Formation Pollutants in Turbulent Premixed Flame

2010 ◽  
Author(s):  
Abdelhalim Bentebbiche ◽  
Denis Veynante
Keyword(s):  
Kinetic Scheme ◽  
Turbulent Flames ◽  
Premixed Flame ◽  
Reactive Flow ◽  
Reactor Model ◽  
Turbulent Premixed Flame ◽  
No Formation ◽  
Stirred Reactor ◽  
Good Issue ◽  
Turbulent Premixed

The objective of this work is to analyze and to model the turbulent flames in the context of coherent flame model. We present a detailed description of equations and the flamelet regimes in turbulent premixed flame. A surface density models proposed here represents a good issue for numerical simulation. Extension of coherent flame model and homogenous stilled reactor model is proposed to consider the dynamics behavior of flame and pollutants formation. From the results of this work it is concluded that the coherent flame model allows surpassing difficulties of the turbulent reactive flow modeling. Calculations based on a semi-global kinetic scheme and flamelet formulation combined with a well stirred reactor analysis of the burnt gases are used and provided reasonably accurate values of CO and NO formation. Also, we have observed that CO is formed near the reaction zone (front flame) but emission of CO2, H2O and NO are formed in the hot gases.

Integration of titrimetric measurement, off-gas analysis and NOx− biosensors to investigate the complexity of denitrification processes

2004 ◽  
Vol 50 (11) ◽  
pp. 135-141 ◽  
Author(s):  
S.H. McMurray ◽  
R.L. Meyer ◽  
R.J. Zeng ◽  
Z. Yuan ◽  
J. Keller
Keyword(s):  
Nox Reduction ◽  
Treatment Plant ◽  
Single Step ◽  
Gas Analysis ◽  
Measuring Process ◽  
Nitrogen Gas ◽  
Detailed Measurement ◽  
On Line ◽  
Kinetics Of ◽  
Denitrification Process

The denitrification process, namely the reduction of nitrate (NO3−) to nitrogen gas (N2), often cannot be simply modelled as a single step process. For a more complete and comprehensive model the intermediates, particularly nitrite (NO2−) and nitrous oxide (N2O), need to be investigated. This paper demonstrates the integration of titrimetric measurements and off-gas analysis with on-line nitrite plus nitrate (NOx−) biosensors, highlighting the necessity of measuring process intermediates with high time-scale resolution to study and understand the kinetics of denitrification. Investigation of activated sludge from a full-scale treatment plant showed a significant accumulation of NO2−, which appeared to impact on the overall denitrification rate measured as NOx− reduction or N2 production. A different sludge obtained from a lab-scale bioreactor produced N2O instead of N2 as the end product of denitrification. The two examples both illustrate the complexity of denitrification and stress the need for the more versatile and detailed measurement procedures, as presented in this paper.

Sign in / Sign up

Export Citation Format

Share Document