Kinetics Modeling on NOx Emissions of a Syngas Turbine Combustor Using Rich-Burn, Quick-Mix, Lean-Burn Combustion Method

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Haoyang Liu ◽  
Wenkai Qian ◽  
Min Zhu ◽  
Suhui Li
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Air Flow ◽  
Outlet Temperature ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Lean Burn ◽  
Kinetics Modeling ◽  
The Rich ◽  
Nox Control

Abstract To avoid flashback issues of the high-H2 syngas fuel, current syngas turbines usually use nonpremixed combustors, which have high NOx emissions. A promising solution to this dilemma is rich-burn, quick-mix, lean-burn (RQL) combustion, which not only reduces NOx emissions but also mitigates flashback. This paper presents a kinetics modeling study on NOx emissions of a syngas–fueled gas turbine combustor using RQL architecture. The combustor was simulated with a chemical reactor network (CRN) model in chemkin-pro software. The combustion and NOx formation reactions were modeled using a detailed kinetics mechanism that was developed for syngas. Impacts of combustor design/operating parameters on NOx emissions were systematically investigated, including combustor outlet temperature, rich/lean air flow split, and residence time split. The mixing effects in both the rich-burn zone and the quick-mix zone were also investigated. Results show that for an RQL combustor, the NOx emissions initially decrease and then increase with combustor outlet temperature. The leading parameters for NOx control are temperature-dependent. At typical modern gas turbine combustor operating temperatures (e.g., <1890 K), the air flow split is the most effective parameter for NOx control, followed by the mixing at the rich-burn zone. However, as the combustor outlet temperature increases, the impacts of air flow split and mixing in the rich-burn zone on NOx reduction become less pronounced, whereas both the residence time split and the mixing in the quick-mix zone become important.

Kinetics Modeling on NOx Emissions of a Syngas Turbine Combustor Using RQL Combustion Method

2019 ◽  
Author(s):  
Haoyang Liu ◽  
Wenkai Qian ◽  
Min Zhu ◽  
Suhui Li
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Air Flow ◽  
Nox Reduction ◽  
Outlet Temperature ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Kinetics Modeling ◽  
The Rich ◽  
Nox Control

Abstract To avoid flashback issues of the high-H2 syngas fuel, current syngas turbines usually use non-premixed combustors, which have high NOx emissions. A promising solution to this dilemma is RQL (rich-burn, quick-mix, lean-burn) combustion, which not only reduces NOx emissions, but also mitigates flashback. This paper presents a kinetics modeling study on NOx emissions of a syngas-fueled gas turbine combustor using RQL architecture. The combustor was simulated with a chemical reactor network model in CHEMKIN-PRO software. The combustion and NOx formation reactions were modeled using a detailed kinetics mechanism that was developed for syngas. Impacts of combustor design/operating parameters on NOx emissions were systematically investigated, including combustor outlet temperature, rich/lean air flow split and residence time split. The mixing effects in both the rich-burn zone and the quick-mix zone were also investigated. Results show that for an RQL combustor, the NOx emissions initially decrease and then increase with combustor outlet temperature. The leading parameters for NOx control are temperature-dependent. At typical modern gas turbine combustor operating temperatures (e.g., < 1890 K), the air flow split is the most effective parameter for NOx control, followed by the mixing at the rich-burn zone. However, as the combustor outlet temperature increases, the impacts of air flow split and mixing in the rich-burn zone on NOx reduction become less pronounced, whereas both the residence time split and the mixing in the quick-mix zone become important.

scholarly journals The GE Rich-Quench-Lean Gas Turbine Combustor

1998 ◽  
Vol 120 (3) ◽  
pp. 502-508 ◽  
Author(s):  
A. S. Feitelberg ◽  
M. A. Lacey
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Coal Gasification ◽  
Perforated Plate ◽  
Combined Cycle ◽  
Development Effort ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Chemical Kinetic Model ◽  
The Rich

The General Electric Company has developed and successfully tested a full-scale, F-class (2550°F combustor exit temperature), rich-quench-lean (RQL) gas turbine combustor, designated RQL2, for low heating value (LHV) fuel and integrated gasification combined cycle applications. Although the primary objective of this effort was to develop an RQL combustor with lower conversion of fuel bound nitrogen to NOx than a conventional gas turbine combustor, the RQL2 design can be readily adapted to natural gas and liquid fuel combustion. RQL2 is the culmination of a 5 year research and development effort that began with natural gas tests of a 2” diameter perforated plate combustor and included LHV fuel tests of RQL1, a reduced scale (6” diameter) gas turbine combustor. The RQL2 combustor includes a 14” diameter converging rich stage liner, an impingement cooled 7” diameter radially-stratified-quench stage, and a backward facing step at the entrance to a 10” diameter film cooled lean stage. The rich stage combustor liner has a novel double-walled structure with narrow circumferential cooling channels to maintain metal wall temperatures within design limits. Provisions were made to allow independent control of the air supplied to the rich and quench/lean stages. RQL2 has been fired for almost 100 hours with LHV fuel supplied by a pilot scale coal gasification and high temperature desulfurization system. At the optimum rich stage equivalence ration NOx emissions were about 50 ppmv (on a dry, 15 percent O2 basis), more than a factor of 3 lower than expected from a conventional diffusion flame combustor burning the same fuel. With 4600 ppmv NH3 in the LHV fuel, this corresponds to a conversion of NH3 to NOx of about 5 percent. As conditions were shifted away from the optimum, RQL2 NOx emissions gradually increased until they were comparable to a standard combustor. A chemical kinetic model of RQL2, constructed from a series of ideal chemical reactors, matched the measured NOx emissions fairly well. The CO emissions were between 5 and 30 ppmv (on a dry, 15 percent O2 basis) under all conditions.

The aerodynamic challenges of aeroengine gas-turbine combustion systems

2014 ◽  
Vol 118 (1204) ◽  
pp. 557-599 ◽  
Author(s):  
J. J. McGuirk
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Great Success ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Lean Burn ◽  
Combustion Systems ◽  
The Rich ◽  
Acoustic Instabilities

Abstract The components of an aeroengine gas-turbine combustor have to perform multiple tasks – control of external and internal air distribution, fuel injector feed, fuel/air atomisation, evaporation, and mixing, flame stabilisation, wall cooling, etc. The ‘rich-burn’ concept has achieved great success in optimising combustion efficiency, combustor life, and operational stability over the whole engine cycle. This paper first illustrates the crucial role of aerodynamic processes in achieving these performance goals. Next, the extra aerodynamic challenges of the ‘lean-burn’ injectors required to meet the ever more stringent NO x emissions regulations are introduced, demonstrating that a new multi-disciplinary and ‘whole system’ approach is required. For example, high swirl causes complex unsteady injector aerodynamics; the threat of thermo-acoustic instabilities means both aerodynamic and aeroacoustic characteristics of injectors and other air admission features must be considered; and high injector mass flow means potentially strong compressor/combustor and combustor/turbine coupling. The paper illustrates how research at Loughborough University, based on complementary use of advanced experimental and computational methods, and applied to both isolated sub-components and fully annular combustion systems, has improved understanding and identified novel ideas for combustion system design.

scholarly journals The GE Rich-Quench-Lean Gas Turbine Combustor

1997 ◽  
Author(s):  
Alan S. Feitelberg ◽  
Michael A. Lacey
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Coal Gasification ◽  
Perforated Plate ◽  
Combined Cycle ◽  
Development Effort ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Chemical Kinetic Model ◽  
The Rich

The General Electric Company has developed and successfully tested a full-scale, ‘F’ class (2550°F combustor exit temperature), rich-quench-lean (RQL) gas turbine combustor, designated RQL2, for low heating value (LHV) fuel and integrated gasification combined cycle applications. Although the primary objective of this effort was to develop an RQL combustor with lower conversion of fuel bound nitrogen to NOx than a conventional gas turbine combustor, the RQL2 design can be readily adapted to natural gas and liquid fuel combustion. RQL2 is the culmination of a 5 year research and development effort that began with natural gas tests of a 2″ diameter perforated plate combustor and included LHV fuel tests of RQL1, a reduced scale (6″ diameter) gas turbine combustor. The RQL2 combustor includes a 14″ diameter converging rich stage liner, an impingement cooled 7″ diameter radially-stratified-quench stage, and a backward facing step at the entrance to a 10″ diameter film cooled lean stage. The rich stage combustor liner has a novel double-walled structure with narrow circumferential cooling channels to maintain metal wall temperatures within design limits. Provisions were made to allow independent control of the air supplied to the rich and quench/lean stages. RQL2 has been fired for almost 100 hours with LHV fuel supplied by a pilot scale coal gasification and high temperature desulfurization system. At the optimum rich stage equivalence ratio NOx emissions were about 50 ppmv (on a dry, 15% O2 basis), more than a factor of 3 lower than expected from a conventional diffusion flame combustor burning the same fuel. With 4600 ppmv NH3 in the LHV fuel, this corresponds to a conversion of NH3 to NOx of about 5%. As conditions were shifted away from the optimum, RQL2 NOx emissions gradually increased until they were comparable to a standard combustor. A chemical kinetic model of RQL2, constructed from a series of ideal chemical reactors, matched the measured NOx emissions fairly well. The CO emissions were between 5 and 30 ppmv (on a dry, 15% O2 basis) under all conditions.

scholarly journals Reduction of NOx Emission from Gas TURBINE COMBUSTOR Applying Fuel-Staged Combustion

2008 ◽  
Vol 2 (1) ◽  
pp. 61
Author(s):  
Mohammad Nazri ◽  
Mohd. Jaafar
Keyword(s):  
Carbon Monoxide ◽  
Gas Turbine ◽  
Main Stage ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Gas Turbine Combustor ◽  
Inside Diameter ◽  
Fuel Staging ◽  
In Series ◽  
The Rich

A two-stage lean/lean gas turbine combustor was developed with low NOx characteristics in each stage using a small radial swirler of 40-mm outlet diameter in the pilot stage. Both flame tubes were arranged in series with the smaller combustor (76 mm inside diameter) as the pilot stage and the larger combustor (140 mm inside diameter) as the main stage. The pilot stage was fuelled via vane passage fuel injector, while the main stage was fuelled around the wall of the exit plane of the pilot stage, using wall fuel injectors. Low NOx emissions were obtained when using fuel staging for methane fuel, as low as 6 ppm. A NO. reduction of more than 40 % was obtained at equivalence ratio of near 0.7, when using fuel staging compared to the non-fuel-staging test. Tests were conducted using methane as fuel. This was achieved at very small increase in carbon monoxide emissions especially near the rich region and with almost no increase at all in the unburned hydrocarbon emissions at the same equivalence ratio.Keywords: NOx emissions, fuel staging, carbon monoxide, swirler.

The Effect of the Sample Line Length on Gas Turbine Emissions Measurement

2017 ◽  
Author(s):  
Thomas James Gill ◽  
Lukai Zheng ◽  
Emamode A. Ubogu ◽  
Ihab Ahmed ◽  
Bhupendra Khandelwal
Keyword(s):  
Gas Turbine ◽  
Residence Time ◽  
Hospital Admissions ◽  
Numerical Study ◽  
Line Length ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Engine Exhaust ◽  
Respiratory Conditions ◽  
Harmful Effects

It is a well-known fact that NO2 has far more harmful effects as compared to NO. NO2 creates ozone, which causes eye irritation and exacerbates respiratory conditions. This leads to an increased emergency departments’ visits and hospital admissions for respiratory issues, especially asthma. Under current situation, majority of regulations deal with total NOx emissions, without looking at the break-up of NO2 and NO. However, there is a feeling in emissions regulation community to implement regulations on NO2 emissions. There are standards to measure total NOx emissions. However, these standards are not equipped enough to measure NO2 emissions accurately. The effect of sample line length on NO2 emissions is not fully understood to date. Also, the standards only suggests maximum of 10 seconds residence time regardless of what the line length is. In this study, a systematic experimental test campaign has been conducted to understand the effect of sample line length on NO2, NO distribution. The residence time was maintained below 10 seconds in accordance with the SAE ARP1256D standards. A Rolls-Royce gas turbine combustor and different calibration cylinders have been used to study the effect of sample line length. A numerical study has also been done to predict the conversion of NO2 to NO. It has been found that with increasing sample line length, more NO2 gets converted to NO and overall NO2 emissions show a reduction, whereas this would not be the case at engine exhaust. This effect of sample line length can be used as a loophole in giving lower NO2 emissions readings.

NOx Correlation for an Industrial 10 MW Non-Premixed Gas Turbine Combustor for High Hydrogen Fuels

2016 ◽  
Author(s):  
Daniel Kroniger ◽  
Manfred Wirsum ◽  
Atsushi Horikawa ◽  
Kunio Okada ◽  
Masahide Kazari
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Hydrogen Content ◽  
Variable Pressure ◽  
Outlet Temperature ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
High Hydrogen ◽  
Operation Conditions

This paper describes a model to predict the nitric oxides (NOx) emissions for a dry non-premixed flame gas turbine combustor at full operation conditions. The NOx correlation considered the combustor pressure, the combustor outlet temperature and the fuel composition from natural gas (NG) to pure hydrogen (H2) fuel. The test data for parametrizing the model was acquired with a high pressure combustion test rig for industrial 10 MWth reverse-flow gas turbine combustors. The experimental results confirm the typical dependencies of NOx emissions. As expected, higher NOx emissions occur with increasing combustor pressure, combustor outlet temperature and hydrogen content of the fuel. The reference NOx model has been derived on the basis of physical approaches for the pressure and temperature effects. The substitution of natural gas with hydrogen is taken into account by a variable pressure exponent and a variable factor in the exponent of the exponential temperature correlation. As a result, the pressure exponent increases with increasing hydrogen. The temperature exponent factor decreases with increasing hydrogen. The model can describe the data set with limitations at high pressure and high hydrogen content fuel operation conditions.

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.

Combustion Characteristics of Small Size Gas Turbine Combustor Fueled by Biomass Gas Employing Flameless Combustion

2007 ◽  
Author(s):  
Masato Hiramatsu ◽  
Yoshifumi Nakashima ◽  
Sadamasa Adachi ◽  
Yudai Yamasaki ◽  
Shigehiko Kaneko
Keyword(s):  
Gas Turbine ◽  
Combustion Efficiency ◽  
Combustion Characteristics ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
Flameless Combustion ◽  
Engine Exhaust ◽  
Micro Gas Turbine

One approach to achieving 99% combustion efficiency (C.E.) and 10 ppmV or lower NOx (at 15%O2) in a micro gas turbine (MGT) combustor fueled by biomass gas at a variety of operating conditions is with the use of flameless combustion (FLC). This paper compares experimentally obtained results and CHEMKIN analysis conducted for the developed combustor. As a result, increase the number of stage of FLC combustion enlarges the MGT operation range with low-NOx emissions and high-C.E. The composition of fuel has a small effect on the characteristics of ignition in FLC. In addition, NOx in the engine exhaust is reduced by higher levels of CO2 in the fuel.

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