NOx Reduction in Gas Turbine Combustors With Compact Non-Premixed Flame Front

2014 ◽  
Author(s):  
V. V. Tsatiashvili ◽  
V. G. Avgustinovich
Keyword(s):  
Flame Front ◽  
Gas Turbine ◽  
Nox Reduction ◽  
Premixed Flame ◽  
Nox Emission ◽  
Nox Formation ◽  
New Approach ◽  
Index Reduction ◽  
Primary Zone ◽  
Low Emission

This paper represents results of R&D efforts towards reducing a bypass turbofan engine NOx emission by 45 % compared with CAEP/6 to meet the ICAO NOx emission goal of 2020. To achieve ICAO NOx technology goal, a new approach is used based on the NOx emission reduction in combustors with non-premixed combustion well proved in operation. The new approach is represented by structured system of low emission combustion principles — a concept of combustor featuring compact non-premixed flame (CNPF). The essence of CNPF concept is in suppression of volume and surface NOx formation sources by flame front blocking in liner primary zone and by increasing of fuel effective burning rate. The paper represents the development of concept up to and including the 4th technology maturity level. It demonstrates CNPF concept independence and interaction with other up-to-date gas turbine low emission concepts. The paper indicates comparison of rig test results between in-service combustor and CNPF adopted combustors carried out on a single liner. A CNPF adopted combustor shows NOx emission index reduction by 35 …47 % at take-off engine conditions. Preliminary estimation shows that it is possible to reach the ICAO goal for NOx emission level of 2020.

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.

Application of Reburning for NOx Control to a Firetube Package Boiler

1985 ◽  
Vol 107 (3) ◽  
pp. 739-743 ◽  
Author(s):  
J. A. Mulholland ◽  
W. S. Lanier
Keyword(s):  
Natural Gas ◽  
Reaction Order ◽  
Nox Reduction ◽  
Process Variable ◽  
Nox Emission ◽  
Boiler Load ◽  
Second Stage ◽  
Primary Zone ◽  
Dominant Process ◽  
Nox Control

A 730 kW (2.5 × 106 Btu/hr) firetube package boiler was used to demonstrate the application of reburning for NOx emission control. An overall reduction of 50 percent from an uncontrolled NOx emission of 200 ppm was realized by diverting 15 percent of the total boiler load to a natural-gas-fired second stage burner. Tests indicate that the overall reaction order of destruction with respect to initial NOx is greater than one; thus, larger reductions can be expected from reburning applications to systems with higher initial NOx. Rich zone stoichiometry has been identified as the dominant process variable. Primary zone stoichiometry and rich zone residence time are parameters that can be adjusted to maximize NOx reduction. Reburning applied to firetube package boilers requires minimal facility modification. Natural gas would appear to be an ideal reburning fuel as nitrogen in the reburning fuel has been shown to inhibit NOx reduction.

scholarly journals Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines

1997 ◽  
Author(s):  
Peter Griebel ◽  
Michael Fischer ◽  
Christoph Hassa ◽  
Eggert Magens ◽  
Henning Nannen ◽  
...  
Keyword(s):  
Research Work ◽  
Nox Formation ◽  
Lean Combustion ◽  
Air Jets ◽  
Primary Zone ◽  
Low Emission ◽  
Measuring Techniques ◽  
Annular Combustor ◽  
High Turbulence ◽  
Secondary Air

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques. Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.

Effects of Burner Interaction on NOx Emission From Swirl Premix Burner in a Gas Turbine Combustor

2014 ◽  
Author(s):  
Cheon Hyeon Cho ◽  
Chae Hoon Sohn ◽  
Ju Hyeong Cho ◽  
Han Seok Kim
Keyword(s):  
Gas Turbine ◽  
Nox Emission ◽  
Gas Turbine Combustor ◽  
Step Size ◽  
Flow Temperature ◽  
Nox Formation ◽  
Air Stream ◽  
Flow Interactions ◽  
Model Chamber ◽  
Wall Interaction

Flame interaction between neighboring burners in a gas turbine combustor is investigated numerically for pursuit of its effect on NOx emission from the burners. In a model chamber or liner, EV burners with double cone are installed. Two burners with the same rotating direction of air stream are adopted and the distance between them is variable from 74.2 mm to 222.6 mm by the step size of 37.1 mm. Gaseous methane and air are adopted as fuel and oxidizer, respectively. From steady-state numerical analyses, flow, temperature, and NO concentration fields are calculated in all computational cases to find their correlation with NOx formation. NOx emission is evaluated at the exit of the model chamber with two burners as a function of burner distance and compared with that from a single burner. In all cases of two-burner calculations, NOx emission is higher than that of a single burner, which results from flow interactions between neighboring burners as well as between a burner and a liner wall. NOx emission is affected significantly by flow and flame interactions between them and strongly depends on burner distance. Burner interaction is divided into two regimes of a burner-burner interaction and a burner-wall interaction depending on the distance. In the former regime, NOx emission is reduced as flame interaction between burners is enhanced and in the latter regime, it is also reduced as interaction between the burner and the liner wall is enhanced.

One-Dimensional Model to Quantify NOx Reduction in Gas Turbines Using EGR

1998 ◽  
Author(s):  
K. K. Botros ◽  
M. J. de Boer ◽  
G. Kibrya
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Nox Reduction ◽  
Simulation Software ◽  
Specific Work ◽  
Dimensional Model ◽  
Nox Formation ◽  
One Dimensional ◽  
Thermal Nox

A one dimensional model based on fundamental principles of gas turbine thermodynamics and combustion processes was constructed to quantify the principle of exhaust gas recirculation (EGR) for NOx reduction. The model utilizes the commercial process simulation software ASPEN PLUS®. Employing a set of 8 reactions including the Zeldovich mechanism, the model predicted thermal NOx formation as function of amount of recirculation and the degree of recirculate cooling. Results show that addition of sufficient quantities of uncooled recirculate to the inlet air (i.e. EGR>∼4%) could significantly decrease NOx emissions but at a cost of lower thermal efficiency and specific work. Cooling the recirculate also reduced NOx at lower quantities of recirculation. This has also the benefit of decreasing losses in the thermal efficiency and in the specific work output. Comparison of a ‘rubber’ and ‘non-rubber’ gas turbine confirmed that residence time is one important factor in NOx formation.

Numerical Analysis of NOx Formation in a Diffusion Flame Combustor Based on a Flamelet Model

2001 ◽  
Author(s):  
Dmitry V. Volkov ◽  
Alexandr A. Belokon ◽  
Dmitry A. Lyubimov ◽  
Vladimir M. Zakharov ◽  
George Opdyke
Keyword(s):  
Diffusion Flame ◽  
Turbulent Mixing ◽  
Flow Distribution ◽  
Nox Emission ◽  
Scalar Dissipation ◽  
3D Flow ◽  
Nox Formation ◽  
Flamelet Model ◽  
Primary Zone ◽  
Consumption Rates

Laminar flamelet models have demonstrated good quality predictions of NOx emission from diffusion flame type combustors. In this paper, the NOx formation process is analyzed by using a flamelet model and 3D flow calculations to take a virtual look inside a combustor. The main phenomena affecting NOx emission are turbulent mixing and the turbulence-chemistry interaction. Local scalar dissipation is the main parameter responsible for the turbulence-chemistry interaction within the flamelet model. At the same time, scalar dissipation is also related to the mixing process. On one hand, higher values of scalar dissipation correspond to higher fuel consumption rates, which decrease the volume of the high temperature zones. On the other hand, higher values of scalar dissipation lead to higher NOx formation rates. Unfortunately, scalar dissipation is not commonly used by combustion engineers because of the difficulty of the clear physical interpretation of this variable and its relationship with the usual parameters. In this paper, the influence of several design features, such as primary zone equivalence ratio and air flow distribution along the liner, is studied relative to scalar dissipation distributions in the combustion zones and to NOx formation. A real industrial diffusion flame combustor is used as an example, and the results can provide a better understanding of real combustor processes. The NOx prediction results are in reasonable agreement with test data.

Kinetics Study of a Staged Combustor Concept for Oxy-Fuel Combustion Gas Turbine Cycles

2019 ◽  
Author(s):  
Wenkai Qian ◽  
Haoyang Liu ◽  
Min Zhu ◽  
Suhui Li
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Chemical Reactor ◽  
Fuel Combustion ◽  
Combustion Gas ◽  
Part Load ◽  
Primary Zone ◽  
Reactor Network

Abstract Oxy-fuel combustion has been identified as a promising technology for CO2 capture and NOx reduction. It has great potential to be applied in gas turbine cycles. Previous studies, however, reveal that simple oxy-fuel combustors suffer from issues like flame blowoff and CO emissions especially at part load, due to the high CO2 content in the combustion atmosphere. In this paper, a staged combustor concept is proposed to mitigate flame blowoff and CO emissions issues for load operations. The conceptual combustor consists of three zones axially: primary zone, CO burnout zone, and dilution zone. All fuel is fed to the primary zone, while O2 is distributed to the primary zone and CO burnout zone. CO2 is distributed to the primary zone and dilution zone. By adjusting the distribution of the O2 and CO2, the primary zone operates at a relatively higher flame temperature at part load, which helps improve the flame blowoff performance. A chemical reactor network model is developed to study the effects of key design/operating parameters on flame blowoff and CO emissions. Results show that the distribution ratios of O2, CO2 and residence time between different zones are the key factors that influence flame blowoff and CO emissions. To mitigate flame blowoff and CO emissions at part load, the distribution of O2 needs to be carefully chosen so that the primary zone operates under near-stoichiometric or slightly lean condition, while the distribution of CO2 to the primary zone also needs to be reduced. The residence time split has stronger influence on CO emissions than CO2 and O2 distribution.

Large-Eddy Simulation in an Industrial Gasturbine Combustor for NOx Prediction

2012 ◽  
Author(s):  
Kohshi Hirano ◽  
Yoshiharu Nonaka ◽  
Yasuhiro Kinoshita ◽  
Nobuyuki Oshima ◽  
Kyohei Matsuya
Keyword(s):  
Large Eddy Simulation ◽  
Gas Turbine ◽  
Emission Reduction ◽  
Premixed Flame ◽  
Nox Emission ◽  
Pollutant Emission ◽  
Gas Turbine Combustor ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Difference

NOx emission reduction is important for developing gas-turbine engines. Predicting the thermal profile and pollutant-emission factor by numerical simulation is effective for reducing the development costs. Here a large eddy simulation coupled with a 2-scalar flamelet approach is applied to the numerical analysis of an industrial gas-turbine combustor. The combustor of an L20A-DLE gas-turbine engine is calculated. Combustor performance under different loads is investigated. NOx production decreases with reducing load, and this tendency agrees well with the experimental results. It is said that NOx production due to a large amount of supplemental burner fuel. NOx production in the simulation is lower than in the experiment. The simulated temperature in the combustor outlet is also lower than the adiabatic temperature. Moreover, the fuel is not burned completely within the combustor region. The difference in the combustion status in a supplemental burner is investigated. For the diffusion flame, a high-temperature region is observed locally owing to the presence of a fuel-rich region. For NOx production, NOx emission reduction is expected using a burner that introduces a premixed flame. From the simulation results, we can estimate NOx production in a gas-turbine combustor. The tendencies in the differences of the loads agreed well with the experimental data, and the superiority of a premixed flame was indicated.

scholarly journals Measurements of Low Level NOx Emission From a Cheng Cycle Gas Turbine

1984 ◽  
Author(s):  
Chung-Nan Chang ◽  
Ramarao Digumarthi
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Nox Reduction ◽  
Steam Injection ◽  
Combustion Characteristics ◽  
Nox Emission ◽  
Pollutant Formation ◽  
Low Level ◽  
Cycle System

Mass steam injection into the combustor of a Cheng Cycle turbine can influence combustion characteristics and pollutant formation. When using a Cheng Cycle system based on a Garrett 831 gas turbine liquid fuel, these influences were studied experimentally. Data obtained to date indicate that significant NOx reduction can be achieved without suffering combustion inefficiency or instability.

The Nature of NOx Formation Within an Industrial Gas Turbine Dry Low Emission Combustor

2005 ◽  
Author(s):  
Khawar J. Syed ◽  
Eoghan Buchanan
Keyword(s):  
Gas Turbine ◽  
Fluid Dynamic ◽  
Chemical Reactor ◽  
Inlet Temperature ◽  
Nox Formation ◽  
Stirred Reactor ◽  
Low Emission ◽  
Wide Range ◽  
Air Mixing ◽  
Industrial Gas Turbine

The NOx formation within a practical lean premixed gas turbine combustor concept has been investigated. The effects of chemical kinetics and fuel/air mixing have been isolated, by adopting an approach, which combines high pressure combustion testing, CFD and chemical reactor modelling. Given the complexities of the underlying fluid dynamic and chemical processes and their interactions, consistency has been sought between experimental and numerical approaches, prior to drawing any conclusions. Two variants of Siemens Industrial Turbomachinery’s dry low emissions combustor have been investigated, one exhibiting near-ideally premixed combustion over a wide range of combustor pressure drop. Perfectly Stirred Reactor analysis, utilising the GRI 3.0 NOx mechanism, shows that NOx formation is dominated by the N2O and Zeldovich routes, with the N2O route being the larger at flame temperatures below 1800–1900K, for systems operating at 14bars, 400°C inlet temperature and at residence times of interest. Other reactions involving H-N-O chemistry are also significant, however the C-H-N-O chemistry has a negligible impact.

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