Low NOx Premixed Combustion of MBtu Fuels in a Research Burner

1996 ◽  
Author(s):  
K. Döbbeling ◽  
A. Eroglu ◽  
D. Winkler ◽  
T. Sattelmayer ◽  
W. Keppel
Keyword(s):  
High Pressure ◽  
Quartz Glass ◽  
Atmospheric Pressure ◽  
Fuel Injection ◽  
Flame Stabilization ◽  
Premix Combustion ◽  
Planar Laser ◽  
Preliminary Study ◽  
Combustion Tests

The paper reports on the development and testing of a premix research burner for MBtu fuels. The burner has a quartz glass annular mixing section and a quartz glass flame tube to allow visualization of the flame. A central lance is used to mount modules for fuel injection, swirl generation and flame stabilization. This allows a large number of variants with different swirl strength, mixing section length, fuel injection geometry and flameholder size and shape to be easily tested. Experiments have been performed at atmospheric pressure and under high pressure conditions (14 bar pressure, 400°C air preheat temperature) for syngas with a H2/CO ratio of up to 5. In a preliminary study the mixing quality of the tested variants has been assessed with planar laser induced fluorescence (LIF). High pressure combustion tests show that low NOx (< 10 vppmd @ 15% O2) premix combustion of MBtu fuels under industrial GT conditions without dilution is feasible.

Low NOx Premixed Combustion of MBtu Fuels in a Research Burner

1997 ◽  
Vol 119 (3) ◽  
pp. 553-558 ◽  
Author(s):  
K. Do¨bbeling ◽  
A. Eroglu ◽  
D. Winkler ◽  
T. Sattelmayer ◽  
W. Keppel
Keyword(s):  
High Pressure ◽  
Quartz Glass ◽  
Atmospheric Pressure ◽  
Fuel Injection ◽  
Flame Stabilization ◽  
Premix Combustion ◽  
Planar Laser ◽  
Preliminary Study ◽  
Combustion Tests

The paper reports on the development and testing of a premix research burner for MBtu fuels. The burner has a quartz glass annular mixing section and a quartz, glass flame tube to allow visualization of the flame. A central lance is used to mount modules for fuel injection, swirl generation, and flame stabilization. This allows a large number of variants with different swirl strength, mixing section length, fuel injection geometry, and flameholder size and shape to be easily tested. Experiments have been performed at atmospheric pressure and under high-pressure conditions (14 bar pressure, 400°C air preheat temperature) for syngas with a H2/CO ratio of up to 5. In a preliminary study, the mixing quality of the tested variants has been assessed with planar laser-induced fluorescence (LIF). High-pressure combustion tests show that low NOx (<10 vppmd @ 15 percent O2) premix combustion of MBtu fuels under industrial GT conditions without dilution is feasible.

The Effect of Ge Segregation on Oxidation of Si

1987 ◽  
Vol 105 ◽  
Author(s):  
E. C. Frey ◽  
N. R. Parikh ◽  
M. L. Swanson ◽  
M. Z. Numan ◽  
W. K. Chu
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Epitaxial Layer ◽  
Atmospheric Pressure ◽  
Oxidation Rate ◽  
Oxidation Temperature ◽  
Pressure Oxidation ◽  
Enhanced Oxidation ◽  
High Pressure Oxidation

AbstractWe have studied oxidation of various Si samples including: Ge implanted Si, CVD and MBE grown Si(0.4–4% Ge) alloys, and MBE grown Si-Si(Ge) superlattices. The samples were oxidized in pyrogenic steam (800–1000°C, atmospheric pressure) and at low temperature and high pressure (740°C, 205 atm of dry O2). The oxidized samples were analyzed with RBS/channeling and ellipsometry.An enhanced oxidation rate was seen for all Ge doped samples, compared with rates for pure Si. The magnitude of the enhancement increased with decreasing oxidation temperature. For steam oxidations the Ge was segregated from the oxide and formed an epitaxial layer at the Si-SiO2 interface; the quality of the epitaxy was highest for the highest oxidation temperatures. For high pressure oxidation the Ge was trapped in the oxide and the greatest enhancement in oxidation rate (>100%) was observed.

Flow Field and Hot Streak Migration Through a High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Tommaso Bacci ◽  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Lorenzo Mazzei ◽  
Bruno Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover, important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities, and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl, and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together.In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners, and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50 deg, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure, and velocity fields) has been evaluated by means of a five-hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

scholarly journals Conversion of Liquid to Gaseous Fuel for Prevaporised Premixed Combustion in Gas Turbines

1997 ◽  
Author(s):  
Y. Wang ◽  
L. Reh ◽  
D. Pennell ◽  
D. Winkler ◽  
K. Döbbeling
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Fuel Oil ◽  
Injection System ◽  
Nox Emissions ◽  
Combustion Tests

Stationary gas turbines for power generation are increasingly being equipped with low emission burners. By applying lean premixed combustion techniques for gaseous fuels both NOx and CO emissions can be reduced to extremely low levels (NOx emissions <25vppm, CO emissions <10vppm). Likewise, if analogous premix techniques can be applied to liquid fuels (diesel oil, Oil No.2, etc.) in gas-fired burners, similar low level emissions when burning oils are possible. For gas turbines which operate with liquid fuel or in dual fuel operation, VPL (Vaporised Premixed Lean)-combustion is essential for obtaining minimal NOx-emissions. An option is to vaporise the liquid fuel in a separate fuel vaporiser and subsequently supply the fuel vapour to the natural gas fuel injection system; this has not been investigated for gas turbine combustion in the past. This paper presents experimental results of atmospheric and high-pressure combustion tests using research premix burners running on vaporised liquid fuel. The following processes were investigated: • evaporation and partial decomposition of the liquid fuel (Oil No.2); • utilisation of low pressure exhaust gases to externally heat the high pressure fuel vaporiser; • operation of ABB premix-burners (EV burners) with vaporised Oil No.2; • combustion characteristics at pressures up to 25bar. Atmospheric VPL-combustion tests using Oil No.2 in ABB EV-burners under simulated gas turbine conditions have successfully produced emissions of NOx below 20vppm and of CO below 10vppm (corrected to 15% O2). 5vppm of these NOx values result from fuel bound nitrogen. Little dependence of these emissions on combustion pressure bas been observed. The techniques employed also ensured combustion with a stable non luminous (blue) flame during transition from gaseous to vaporised fuel. Additionally, no soot accumulation was detectable during combustion.

Parametric Study to Optimize Air/Fuel Mixing for Lean, Premix Combustion Systems

2002 ◽  
Author(s):  
Ibrahim Yimer ◽  
Ian Campbell
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Fuel Mixture ◽  
Statistical Technique ◽  
Gas Temperature ◽  
Physical Processes ◽  
Mixture Preparation ◽  
Premix Combustion ◽  
Planar Laser ◽  
Set Up

New designs of gas turbine combustors for power generation applications have to meet ever-tightening emission standards (mainly NOx, CO and UHC) while operating at high combustor pressures. This requires a detailed understanding of the physical processes involved. The air-fuel mixture preparation is a critical step in most advanced gas turbine combustion strategies to achieve lower emissions. It has long been established that the level of unmixedness between the fuel and air is strongly tied with NOx levels. The present paper applies the statistical technique of Design Of Experiments (DOE) to a generic mixer set-up that includes an axial swirler, with fuel injected at discrete locations and transverse to the flow. The objective is to identify influential design and operating parameters that will provide rapid and enhanced mixing. The parameters tested include Swirl strength as measured by the Swirl number, Swirl type (Constant angle vs. Free vortex), number and momentum of fuel injection sites and gas temperature. Planar Laser Induced Fluorescence of acetone (PLIF) was used to quantify mixing at various planar locations in the mixing section. Commercial CFD software is used to model the flow field and predict the spatial mixing at selected conditions. Comparisons are made with experimental measurements with the aim to validate the CFD code and also on comparing the model results with the measurements.

Investigation of Hydrogen Enriched Methane Flame in a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

2017 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
Jens Klingmann
Keyword(s):  
Atmospheric Pressure ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Flame Stabilization ◽  
Oh Radicals ◽  
Burner Exit ◽  
Low Emission ◽  
Planar Laser ◽  
Pilot Fuel ◽  
Fuel Mixtures

Experiments were performed on a prototype 4th generation DLE (dry low emission) burner under atmospheric pressure conditions to investigate the effects of hydrogen (H2) enrichment on methane (CH4) flames. The burner assembly was designed to have three concentrically arranged premixed sections: an outer Main section, an intermediate section (Pilot) and a central pilot body termed the RPL (Rich-Pilot-Lean) section. The Planar laser-induced fluorescence (PLIF) of OH radicals together with flame chemiluminescence imaging were employed for studying the local flame characteristics so as to be able to investigate the turbulence-flame interactions and the location of the reaction zone at the burner exit. Flames were investigated for three different fuel mixtures having hydrogen (H2)/methane (CH4) in vol. % concentration of 0/100, 25/75 and 50/50. The results show that the characteristics of the flames are clearly affected by the addition of hydrogen and the effects are expected due to the faster reaction rate, higher diffusivity and higher laminar burning velocity of H2. Enriching the flame with H2 at a constant global phi (ϕ) is found to shorten the total extension of the flame due to the higher laminar flame speed. The OH signal distribution becomes thicker and more pronounced due to the higher production of OH radicals, and the flame stabilization zone that is produced after the burner throat, moves further downstream. At a constant global ϕ in altering the RPL and the Pilot ϕ, similar changes for both 0/100 and 25/75 (in vol. %) of the H2/CH4 fuel mixtures can be observed. At a rich RPL ϕ, the secondary RPL flame contributes to the main flame and to determining the flame stabilization position. The flame stabilization zone located after the burner throat moves further downstream with an increase in the RPL ϕ. When the PFR (Pilot fuel ratio) increases, the extension of the flame shortens and the flame stabilization zone moves upstream. Combustion emissions were also determined so as to observe the effects of the H2 enrichment on the NOX level.

Laser-Based Investigation on a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

2016 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
Jens Klingmann
Keyword(s):  
Atmospheric Pressure ◽  
Combustion Products ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Oh Radicals ◽  
Burner Exit ◽  
Planar Laser ◽  
Pilot Fuel ◽  
Intermediate Section ◽  
Primary Combustion Products

Experiments were performed at atmospheric pressure conditions on the prototype 4th generation DLE burner. The combustion changes that occur for alteration of the operating conditions by changing the equivalence ratios (ϕ) for CH4 as fuel at different sections of the burner, were optically investigated. The burner assembly has three concentrically arranged premixed burner sections: an outer Main section, an intermediate section (Pilot) and a central pilot body or pre-chamber combustor, called RPL (Rich-Pilot-Lean) section. All sections are facilitated to vary equivalence ratios to achieve optimal combustion. Planar laser-induced fluorescence (PLIF) of OH radicals and flame chemiluminescence imaging were applied to study the local flame characteristics in order to investigate turbulence-flame interaction and formation of reaction zone at the burner exit. The results show that the position and shape of the flame are clearly affected by the variation of equivalence ratios at different sections of the burner. During the experiments, first the RPL, then the Pilot and the Main flame were added in a step wise manner keeping constant the total air flow for the global ϕ = 0.5 in order to understand the flame contributions from the different combustion sections. It is observed that for the RPL fuel lean conditions, the primary combustion starts and reaches completion before exiting the burner throat while for rich conditions, the residual fuel escapes out through the RPL exit with primary combustion products and starts secondary combustion along with the Pilot and Main combustion. At the global ϕ = 0.5, for changing the RPL ϕ from lean to rich conditions, the flame stabilization region moves downstream of the burner exit and the flame front fluctuation along inner shear layer increases. For increasing the global ϕ and increasing the Pilot fuel ratio (PFR) without changing the RPL and the global ϕ, the total extension of the flame becomes shorter and the flame stabilization region moves upstream.

Experimental Investigation of the Influence of Burner Geometry on Flame Characteristics at a Dry Low Emission Industrial Prototype Burner at Atmospheric Pressure Conditions

2017 ◽  
Author(s):  
Arman Ahamed Subash ◽  
Robert Collin ◽  
Marcus Aldén ◽  
Atanu Kundu ◽  
Jens Klingmann
Keyword(s):  
Atmospheric Pressure ◽  
Recirculation Zone ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Oh Radicals ◽  
Flow Area ◽  
Burner Exit ◽  
Low Emission ◽  
Planar Laser ◽  
Conical Section

Laser based investigations were performed on a prototype 4th generation DLE (dry low emission) burner under atmospheric pressure conditions to study the effects of changing burner geometry on the flame. In a full burner configuration, a divergent conical section termed the Quarl is located after the burner exit for expanding the flow area and holding the flame. The planar laser-induced fluorescence (PLIF) of OH radicals together with the flame chemiluminescence imaging were employed to study the flame characteristics under the conditions with and without Quarl using CH4 as fuel to understand the influence of Quarl on the flame. When there is no Quarl, the flame has more freedom to expand at the burner exit and with an increase in the global equivalence ratio (ϕ), the width of the flame increases and the total extension of the flame shortens. For all the global ϕ considered here, the total extension of the flame is shorter under the condition without Quarl in comparison to the one with Quarl. For a richer global ϕ (ϕ ≥ 0.46) the outer recirculation zones (ORZs) are not observed under the condition with Quarl, but are observed without Quarl along with the inner recirculation zone. Without Quarl conditions, equivalence ratios (ϕ) of the concentrically arranged three sections of the burner: an outer Main section, an intermediate section (Pilot) and a central pilot body or pre-chamber combustor, termed the RPL (Rich-Pilot-Lean) sections were altered. The results show that at a constant global ϕ, with an increase in the RPL ϕ and the Pilot ϕ, the flame shortens and expands radially as well as the flame stabilization zone that is produced after the burner exit moves further downstream. At a richer global ϕ, the ORZ is observed along with the inner recirculation zone of the flame. Otherwise, with an increase in global ϕ, the changes in the flame shape, in the flame fluctuation and in the flame stabilization position follow similar trends as for increasing the Pilot ϕ and the RPL ϕ. Additionally, combustion emissions were obtained to observe the effects on NOX level for different operating conditions with and without Quarl.

Flow Field and Hot Streak Migration Through High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Author(s):  
T. Bacci ◽  
T. Lenzi ◽  
A. Picchi ◽  
L. Mazzei ◽  
B. Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together. In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50°, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure and velocity fields) has been evaluated by means of a five hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

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