scholarly journals Short overview on combustion systems scale‐up with emphasis on NOx emissions of gas‐fired furnaces

2021 ◽  
Author(s):  
Eugen Drubetskoi ◽  
Sven Eckart ◽  
Hartmut Krause
Keyword(s):  
Scale Up ◽  
Nox Emissions ◽  
Short Overview ◽  
Combustion Systems

Jet Shear Layer Size and Number Influences on Grid Plate Direct Fuel Injection Shear Layer Mixing Low NOx Gas Turbine Combustion With Fuel Staging for Power Turn Down

2008 ◽  
Author(s):  
Gordon E. Andrews ◽  
S. A. R. Ahmed
Keyword(s):  
Shear Layer ◽  
Gas Turbine ◽  
Fuel Injection ◽  
Scale Up ◽  
Shear Layers ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Round Jet ◽  
Fuel Staging ◽  
Four Levels

The scale up of jet shear layer low NOx concepts for compact gas turbine applications is considered using natural gas as the fuel with all experiments at one atmosphere pressure and 600K air inlet temperature. A 76mm diameter cylindrical combustor with 4 round jet shear layers was compared with a near double scale combustor with 140mm diameter and 4 round jet shear layers with the same total blockage as for the smaller combustor. This is compared with 16 round jet shear layers of the same diameter as for the smaller combustor. The shear layer air holes were fuelled by eight radial inward fuel injection holes in each shear layer jet. All three designs had acceptable combustion efficiencies, but the NOx emissions were considerably higher for the 4 shear layer design in the larger combustion. When the same shear layer hole size was used and the number increased in the larger combustor the NOx emissions were identical. Changing the shape of the hole from circulat to slot for the same area, considerably reduced the NOx in the four hole 76mm combustor, but had little effect on the 16 hole 140mm combustor. Fuel staging within the array of shear layers was successfully demonstrated for four levels of fuel staging. There was some intermixing of air from the unfuelled jets, but this had only a small effect on the combustion efficiency and flame stability. A practical range of simulated power turndown was demonstrated with little NOx penalty. This was achieved with no wall between the staged shear layer regions and hence leads to very compact combustor designs.

Large-Eddy Simulation of a Reacting Jet in Cross Flow With NOx Prediction

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Johannes Weinzierl ◽  
Michael Kolb ◽  
Denise Ahrens ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Large Eddy Simulation ◽  
Cross Flow ◽  
Nox Emissions ◽  
Staged Combustion ◽  
Nox Formation ◽  
Full Load ◽  
Eddy Simulation ◽  
Jet In Cross Flow ◽  
Large Eddy ◽  
Combustion Systems

The reduction of full and part load emissions and the increase of the turndown ratio are important goals for gas turbine combustor development. Combustion techniques, which generate lower NOx emissions than unstaged premixed combustion in the full load range, and which have the potential of reducing minimum load while complying with emission legislation, are of high technical interest. Therefore, axial-staged combustion systems have been designed, either with or without expansion in a turbine stage between both stages. In its simpler form without intermediate expansion stage, a flow of hot combustion products is generated in the first stage of the premixed combustor, which interacts with the jets of premixed gas injected into the second stage. The level of NOx formation during combustion of the premixed jets in the hot cross flow determines the advantage of axially staged combustion regarding full load NOx emission reduction. Employing large-eddy simulation in openfoam, a tool has been developed, which allows to investigate staged combustion systems including not only temperature distribution but also NOx emissions under engine conditions. To be able to compute NOx formation correctly, the combustion process has to be captured with sufficient level of accuracy. This is achieved by the partially stirred reactor model. It is combined with a newly developed NOx model, which is a combination of a tabulation technique for the NOx source term based on mixture fraction and progress variable and a partial equilibrium approach. The NOx model is successfully validated with generic burner stabilized flame data and with measurements from a large-scale reacting jet in cross flow experiment. The new NOx model is finally used to compute a reacting jet in cross flow under engine conditions to investigate the NOx formation of staged combustion in detail. The comparison between the atmospheric and the pressurized configuration gives valuable insight in the NOx formation process. It can be shown that the NOx formation within a reacting jet in cross flow configuration is reduced and not only diluted.

scholarly journals The Application of DLN Technology to the Tornado and Tempest Industrial Gas Turbines

1997 ◽  
Author(s):  
Michael B. Boyns ◽  
Rajeshri Patel
Keyword(s):  
Power Generation ◽  
Reaction Zone ◽  
Gas Turbines ◽  
Electrical Power ◽  
Scale Up ◽  
Nox Emissions ◽  
New Production ◽  
The Tempest ◽  
Industrial Gas Turbines ◽  
Base Load

Dry low NOX combustion technology has been successfully applied to the EGT Tornado and Tempest industrial gas turbines. This lean-premix technology has been based on that being employed in the EGT Typhoon gas turbine, as reported by Norster & De Pietro (1996) but with a number of modifications to suit the individual engines. The Tornado is a 6.1 MWe machine designed in the late 1970’s for power generation and mechanical drive applications. The worldwide emissions legislation of recent years has provided the requirement to reduce NOX emissions in the exhaust, both for new machines and for those already in operation. Hence a system suitable for retrofitting as well as new production was required. The Tornado utilises similar burners to the Typhoon but with different combustion chambers and a different centre casing from the standard Tornado. Due to the differing cycle conditions, a different reaction zone stoichiometry has been used. A short rig test program followed by engine testing have achieved NOX emissions at base load significantly lower than the initial program target of 42 ppmv and led to the program target being revised to 25 ppmv. The Tempest, launched into the market in 1995 produces 7.49 MWe in single shaft configuration and is aimed at the electrical power generation market. To comply with current emissions legislation, a DLN system has been developed. The Tempest is a 25% scale up of the Typhoon but its mechanical design incorporates a simplified main and pilot burner arrangement and a fully fabricated combustor. At base load, the Tempest operates at a higher turbine entry temperature than the Typhoon but has been designed such that the equivalence ratio in the reaction zone is slightly lower. A comprehensive test programme has demonstrated hardware which significantly improves upon the target emissions limit of 25 ppmv NOX.

Chemical Kinetic Modeling of Ignition and Emissions From Natural Gas and LNG Fueled Gas Turbines

2012 ◽  
Author(s):  
P. Gokulakrishnan ◽  
C. C. Fuller ◽  
R. G. Joklik ◽  
M. S. Klassen
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Chemical Kinetic ◽  
Higher Order ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Combustion Systems

Single digit NOx emission targets as part of gas turbine design criteria require highly accurate modeling of the various NOx formation pathways. The concept of lean, premixed combustion is adopted in various gas turbine combustor designs, which achieves lower NOx levels by primarily lowering the flame temperature. At these conditions, the post-flame thermal-NOx pathway contribution to the total NOx can be relatively small compared to that from the prompt-NOx and the N2O-route, which are enhanced by the super-equilibrium radical pathway at the flame front. In addition, new sources of natural gas fuel (e.g., imported LNG) with widely varying chemical compositions including higher order hydrocarbon components, impact flame stability, lean blow-out limits and emissions in existing lean premixed combustion systems. Also, the presence of higher order hydrocarbons can increase the risk of flashback induced by autoignition in the premixing section of the combustor. In this work a detailed chemical kinetic model was developed for natural gas fuels that consist of CH4, C2H6, C3H8, nC4H10, iC4H10, and small amounts of nC5H12, iC5H12 and nC6H14 in order to predict ignition behavior at typical gas turbine premixing conditions and to predict CO and NOx emissions at lean premixed combustion conditions. The model was validated for different NOx-pathways using low and high pressure laminar premixed flame data. The model was also extended to include a vitiated kinetic scheme to account for the influence of exhaust gas recirculation on fuel oxidation. The model was employed in a chemical reactor network to simulate a laboratory scale lean premixed combustion system to predict CO and NOx. The current kinetic mechanism demonstrates good predictive capability for NOx emissions at lower temperatures typical of practical lean premixed combustion systems.

Low NOx Primary Zones Using Jet Mixing Shear Layer Combustion

1988 ◽  
Author(s):  
U. S. Abdul Hussain ◽  
G. E. Andrews ◽  
W. G. Cheung ◽  
A. R. Shahabadi
Keyword(s):  
Natural Gas ◽  
Shear Layer ◽  
Gas Turbines ◽  
Scale Up ◽  
Combustion Efficiency ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Jet Mixing ◽  
Primary Zone

An interacting radial and axial multi jet shear layer combustion system is described that has the rapid fuel and air mixing characteristics necessary for low NOx emissions. The radial jet has the fuel mixed with a proportion of the total primary zone flow and a 30% proportion was investigated. This radial jet was fuel rich at most primary zone operating conditions and ensured a flame stability far superior to the premixed situation. The scale up of the design from a 76mm to a 140mm diameter combustor was investigated. It was demonstrated that the distance the radial jet travelled before encountering the rapid mixing with the axial jets, had a strong influence on the combustion efficiency and NOx emissions. For both the 76 and 140mm combustors it was shown that the NOx emissions with propane were 50% greater than those for natural gas. It was also demonstrated that the low NOx emissions of the 76mm system were retained in the larger combustor with the same single central fuel injector design. There was a significant increase in NOx for some 140mm combustor configurations, but the emissions corrected to 15% oxygen below 10ppm were demonstratred, with a high combustion efficiency. The design thus demonstrated, in a practical combustor size, the potential for a dry solution to the NOx emissions problem of natural gas fired industrial gas turbines.

Large Eddy Simulation of a Reacting Jet in Cross Flow With NOx Prediction

2016 ◽  
Author(s):  
Johannes Weinzierl ◽  
Michael Kolb ◽  
Denise Ahrens ◽  
Christoph Hirsch ◽  
Thomas Sattelmayer
Keyword(s):  
Large Eddy Simulation ◽  
Cross Flow ◽  
Nox Emissions ◽  
Staged Combustion ◽  
Nox Formation ◽  
Full Load ◽  
Eddy Simulation ◽  
Jet In Cross Flow ◽  
Large Eddy ◽  
Combustion Systems

The reduction of full and part load emissions and the increase of the turndown ratio are important goals for gas turbine combustor development. Combustion techniques, which generate lower NOx emissions than unstaged premixed combustion in the full load range, and which have the potential of reducing minimum load while complying with emission legislation, are of high technical interest. Therefore axial staged combustion systems have been designed, either with or without expansion in a turbine stage between both stages. In its simpler form without intermediate expansion stage a flow of hot combustion products is generated in the first stage of the premixed combustor, which interacts with the jets of premixed gas injected into the second stage. The level of NOx formation during combustion of the premixed jets in the hot cross flow determines the advantage of axially staged combustion regarding full load NOx emission reduction. Employing Large Eddy Simulation in OpenFOAM, a tool has been developed, which allows to investigate staged combustion systems including not only temperature distribution but also NOx emissions under engine conditions. To be able to compute NOx formation correctly the combustion process has to be captured with sufficient level of accuracy. This is achieved by the partially stirred reactor model. It is combined with a newly developed NOx model, which is a combination of a tabulation technique for the NOx source term based on mixture fraction and progress variable and a partial equilibrium approach. The NOx model is successfully validated with generic burner stabilized flame data and with measurements from a large scale reacting jet in cross flow experiment. The new NOx model is finally used to compute a reacting jet in cross flow under engine conditions to investigate the NOx formation of staged combustion in detail. The comparison between the atmospheric and the pressurized configuration gives valuable insight in the NOx formation process. It can be shown that the NOx formation within a reacting jet in cross flow configuration is reduced and not only diluted.

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