scholarly journals One-Dimensional Predictive Emission Monitoring Model for Gas Turbine Combustors

1997 ◽  
Author(s):  
K. K. Botros ◽  
M. J. de Boer ◽  
G. R. Price ◽  
G. Kibrya
Keyword(s):  
Gas Turbine ◽  
Flow Reactor ◽  
Plug Flow ◽  
Flame Length ◽  
Simulation Software ◽  
Nox Formation ◽  
One Dimensional ◽  
Monitoring Model ◽  
Emission Monitoring ◽  
Thermal Nox

Current predictive emission monitoring (PEM) techniques are briefly reviewed and the concept for a general predictive model was favorably evaluated. Utilizing the commercial process simulation software ASPEN PLUS®, a one dimensional model based on fundamental principles of gas turbine thermodynamics and combustion processes was constructed. Employing a set of 22 reactions including the Zeldovich mechanism, the model predicted for thermal NOx formation. It accounted for combustor geometry, dilution air injection along the combustor annulus, convective heat transfer across the liner, flame length, and full-load inlet flows. The combustor was subdivided into slices, each of which was modeled by a plug flow reactor, giving insight into profiles of NOx formation, species concentration and temperature along the combustor’s length, as well as quantifying the residence time in the combustor. The simulation predicted the levels of NOx for a particular gas turbine combustor and determined the effects of various parameters, such as flame length, hydrocarbon conversion ratio and recycle zones.

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.

Uncertainty Quantification of NOx Emission Due to Operating Conditions and Chemical Kinetic Parameters in a Premixed Burner

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Sajjad Yousefian ◽  
Gilles Bourque ◽  
Rory F. D. Monaghan
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Quantification ◽  
Gas Turbine ◽  
Flow Reactor ◽  
Epistemic Uncertainty ◽  
Plug Flow ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Nox Emission ◽  
Gas Turbine Combustion

Many sources of uncertainty exist when emissions are modeled for a gas turbine combustion system. They originate from uncertain inputs, boundary conditions, calibration, or lack of sufficient fidelity in a model. In this paper, a nonintrusive polynomial chaos expansion (NIPCE) method is coupled with a chemical reactor network (CRN) model using Python to quantify uncertainties of NOx emission in a premixed burner. The first objective of uncertainty quantification (UQ) in this study is development of a global sensitivity analysis method based on the NIPCE method to capture aleatory uncertainty on NOx emission due to variation of operating conditions. The second objective is uncertainty analysis (UA) of NOx emission due to uncertain Arrhenius parameters in a chemical kinetic mechanism to study epistemic uncertainty in emission modeling. A two-reactor CRN consisting of a perfectly stirred reactor (PSR) and a plug flow reactor (PFR) is constructed in this study using Cantera to model NOx emission in a benchmark premixed burner under gas turbine operating conditions. The results of uncertainty and sensitivity analysis (SA) using NIPCE based on point collocation method (PCM) are then compared with the results of advanced Monte Carlo simulation (MCS). A set of surrogate models is also developed based on the NIPCE approach and compared with the forward model in Cantera to predict NOx emissions. The results show the capability of NIPCE approach for UQ using a limited number of evaluations to develop a UQ-enabled emission prediction tool for gas turbine combustion systems.

Autoignition of Hydrogen and Air Inside a Continuous Flow Reactor With Application to Lean Premixed Combustion

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
D. J. Beerer ◽  
V. G. McDonell
Keyword(s):  
Gas Turbine ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Initial Conditions ◽  
Premixed Combustion ◽  
Nox Formation ◽  
Lean Premixed Combustion ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Lean Premixed

With the need to reduce carbon emissions such as CO2, hydrogen is being examined as potential “clean” fuel for the future. One potential strategy is lean premixed combustion, where the fuel and air are allowed to mix upstream before entering the combustor, which has been proven to curb NOx formation in natural gas fired engines. However, premixing hydrogen and air may increase the risk of autoignition before the combustor, resulting in serious engine damage. A flow reactor was set up to test the ignition delay time of hydrogen and air at temperatures relevant to gas turbine engine operations to determine maximum possible mixing times. The results were then compared to past experimental work and current computer simulations. The current study observed that ignition is very sensitive to the initial conditions. The ignition delay times follow the same general trend as seen in previous flow reactor studies: ignition within hundreds of milliseconds and relatively low activation energy. An experimentally derived correlation by Peschke and Spadaccini (1985, “Determination of Autoignition and Flame Speed Characteristics of Coal Gases Having Medium Heating Values,” Research Project No. 2357-1, Report No. AP-4291) appears to best predict the observed ignition delay times. Homogenous gas phase kinetics simulations do not appear to describe ignition well in these intermediate temperatures. Therefore, at the moment, only the current empirical correlations should be used in predicting ignition delay at engine conditions for use in the design of gas turbine premixers. Additionally, fairly large safety factors should still be considered for any design to reduce any chance of autoignition within the premixer.

Effect of Operational Parameters on Combustion and Emissions in an Industrial Gas Turbine Combustor

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Mohsen D. Emami ◽  
Hamidreza Shahbazian ◽  
Bengt Sunden
Keyword(s):  
Gas Turbine ◽  
Mixture Fraction ◽  
Flow Characteristics ◽  
Combustion Efficiency ◽  
Fuel Temperature ◽  
Operational Parameters ◽  
Nox Formation ◽  
First Case ◽  
Thermal Nox ◽  
Industrial Gas Turbine

Enhancing a combustion system requires increased combustion efficiency, fuel savings, and reduction of combustion emissions. In this paper, the combustion of CH4 in the combustor of an industrial gas turbine is studied and NO and CO formation/emission is simulated numerically. The objective of the current work is to investigate the influence of combustive parameters and varying the percentage of distributed air flow rate via burning, recirculation, and dilution zone on the reactive flow characteristics, NOx and CO emissions. The governing equations of mass, momentum, energy, turbulence quantities Renormalized group (RNG) (k–ε), mixture fraction and its variance are solved by the finite volume method. The formation and emission of NOx is numerically simulated in a postprocessing fashion, due to the low concentration of the pollutants as compared to the main combustion species. The present work focuses on different physical mechanisms of NOx formation. The thermal-NOx and prompt-NOx mechanism are considered for modeling the NOx source term in the transport equation. Results show that in a gaseous-fueled combustor, the thermal NOx is the dominant mechanism for NOx formation. Particularly, the simulation provides more insight into the correlation between the maximum combustor temperature, exhaust average temperatures, and the thermal NO concentration. Results indicate that the exhaust temperature and NOx concentration decrease while the excess air factor increases. Moreover, results demonstrate that as the combustion air temperature increases, the combustor temperature increases and the thermal NOx concentration increases dramatically. Furthermore, results demonstrate that the NO concentration at the combustor exit is at maximum value in a swirl angle of 55 deg and a gradual rise in the NOx concentration is detected as the combustion fuel temperature increases. In addition, results demonstrate that the air distribution of the first case at laboratory conditions is optimal where the mass fractions of NO and CO are minimum.

A Semi-Analytical Finite Rate Two-Reactor Model for Gas Turbine Combustors

1998 ◽  
Vol 120 (3) ◽  
pp. 495-501 ◽  
Author(s):  
J. H. Tonouchi ◽  
T. J. Held ◽  
H. C. Mongia
Keyword(s):  
Gas Turbine ◽  
Flow Reactor ◽  
Plug Flow ◽  
Aircraft Engine ◽  
Frequency Function ◽  
Reactor Model ◽  
Finite Rate ◽  
Gas Turbine Combustors ◽  
Primary Zone ◽  
Definition Of

A gas turbine combustor is modeled using a two-reactor, finite-rate mixing and chemistry gas particle approach. The first reactor, used to simulate combustion in the primary zone, permits independent definition of the rates of macromixing and micromixing within the reactor, and the amount of premixing of fuel and air entering the reactor. Finite-rate macromixing is simulated by consideration of the fluid particle residence time distribution frequency function and the ages of the particles in the reactor. Finite-rate micromixing is simulated using a modified Coalescence-Dispersion (C-D) model. The second reactor model simulates combustion in the dilution zone of the combustor, and is modeled as a plug flow reactor with cross-flowing jets of dilution air and co-flowing streams of cooling film air. The primary zone reactor model predicts physically reasonable trends in mean temperature, and CO and NOx emissions as the macromixing and micromixing parameters are varied with respect to the perfectly stirred reactor limit. The model also has shown to predict the correct trends in modeling NOx and CO emissions from aircraft engine gas turbine combustors.

Effects of Hydrogen Fueling on NOx Emissions: A Reactor Model Approach for an Industrial Gas Turbine Combustor

2017 ◽  
Author(s):  
D. Kroniger ◽  
M. Lipperheide ◽  
M. Wirsum
Keyword(s):  
Gas Turbine ◽  
Flow Reactor ◽  
Plug Flow ◽  
Nox Emissions ◽  
Flame Zone ◽  
Gas Turbine Combustor ◽  
Reactor Model ◽  
Stirred Reactor ◽  
Set Up ◽  
Reactor Network

Addition of hydrogen (H2) to gas turbine fuel has recently become a topic of interest facing the global challenges of CO2 free combustion. As a drawback, Nitrogen oxide (NOx) emissions are likely to increase in hydrogen-rich fuel combustion which in return limits the use of the technology. In the course of this development, a model-based quantification of NOx emission increase by fuel flexibility may identify possible operation ranges of this technology. This paper evaluates the effect of an increased hydrogen fraction in the fuel on the NOx emissions of a non-premixed 10 MWth gas turbine combustor. A simple reactor network model has been set up using a perfectly stirred reactor (PSR) to simulate the flame zone and a plug flow reactor (PFR) to simulate the post flame zone. The change of residence time in the flame zone is accounted for by an empirical expression. The model is validated against data from high-pressure test rig experiments of an industrial non-premixed gas turbine combustor. The model results are in good agreement with the experimental data. Based on the model results, a fundamental correlation of the effect of hydrogen on the NOx emissions is formulated.

Uncertainty Quantification of NOx Emission due to Operating Conditions and Chemical Kinetic Parameters in a Premixed Burner

2018 ◽  
Author(s):  
Sajjad Yousefian ◽  
Gilles Bourque ◽  
Rory F. D. Monaghan
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Quantification ◽  
Gas Turbine ◽  
Flow Reactor ◽  
Epistemic Uncertainty ◽  
Plug Flow ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Nox Emission ◽  
Gas Turbine Combustion

Many sources of uncertainty exist when emissions are modelled for a gas turbine combustion system. They originate from uncertain inputs, boundary conditions, calibration, or lack of sufficient fidelity in the model. In this paper, a non-intrusive polynomial chaos expansion (NIPCE) method is coupled with a chemical reactor network (CRN) model using Python to rigorously quantify uncertainties of NOx emission in a premixed burner. The first objective of the uncertainty quantification (UQ) in this study is development of a global sensitivity analysis method based on NIPCE to capture aleatory uncertainty due to the variation of operating conditions and input parameters. The second objective is uncertainty analysis of Arrhenius parameters in the chemical kinetic mechanism to study the epistemic uncertainty in the modelling of NOx emission. A two-reactor CRN consisting of a perfectly stirred reactor (PSR) and a plug flow reactor (PFR) is constructed in this study using Cantera to model NOx for natural gas at the relevant operating conditions for a benchmark premixed burner. UQ is performed through the use of a number of packages in Python. The results of uncertainty and sensitivity analysis using NIPCE based on point collocation method (PCM) are then compared with the results of advanced Monte Carlo simulation (MCS). Surrogate models are also developed based on the NIPCE approach and compared with the forward model in Cantera to predict NOx emissions. The results show the capability of NIPCE approach for UQ using a limited number of evaluations to develop a UQ-enabled emission prediction tool for gas turbine combustion systems.

scholarly journals A Semi-Analytical Finite Rate Two-Reactor Model for Gas Turbine Combustors

1997 ◽  
Author(s):  
J. H. Tonouchi ◽  
T. J. Held ◽  
H. C. Mongia
Keyword(s):  
Gas Turbine ◽  
Flow Reactor ◽  
Plug Flow ◽  
Aircraft Engine ◽  
Frequency Function ◽  
Reactor Model ◽  
Finite Rate ◽  
Gas Turbine Combustors ◽  
Primary Zone ◽  
Definition Of

A gas turbine combustor is modeled using a two-reactor, finite-rate mixing and chemistry gas particle approach. The first reactor, used to simulate combustion in the primary zone, permits independent definition of the rates of macromixing and micromixing within the reactor, and the amount of premixing of fuel and air entering the reactor. Finite-rate macromixing is simulated by consideration of the fluid particle residence time distribution frequency function and the ages of the particles in the reactor. Finite-rate micromixing is simulated using a modified Coalescence-Dispersion (C-D) model. The second reactor model simulates combustion in the dilution zone of the combustor, and is modeled as a plug flow reactor with cross-flowing jets of dilution air and co-flowing streams of cooling film air. The primary zone reactor model predicts physically reasonable trends in mean temperature, and CO and NOx emissions as the macromixing and micromixing parameters are varied with respect to the perfectly-stirred reactor limit. The model also has shown to predict the correct trends in modeling NOx and CO emissions from aircraft engine gas turbine combustors.

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