Investigation of Distributed Combustion for Gas Turbine Application: Forward Flow Configuration

2010 ◽  
Author(s):  
Vaibhav K. Arghode ◽  
Ashwani K. Gupta
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Spontaneous Ignition ◽  
Forward Flow ◽  
Combustion Modes ◽  
Flow Configurations ◽  
Thermal Intensity ◽  
Jet Characteristics

Colorless Distributed Combustion (CDC) has been investigated here for high efficiency and ultra low pollution gas turbine combustors applications. In this paper forward flow configurations have been examined. Basic requirement for CDC is carefully tailored mixture preparation prior to ignition through a combination of product gas recirculation, controlled mixing between the fresh combustion air and recirculated gases to form hot and diluted oxidizer. Rapid mixing between the injected fuel and hot oxidizer is desirable prior to spontaneous ignition of the mixture in the entire combustion zone to achieve distributed combustion reactions. Distributed reactions can also be achieved in premixed mode of operation with sufficient entrainment of burned gases and faster turbulent mixing between the reactants. In the present investigation forward flow modes are considered in which three non-premixed and one premixed combustion mode have been examined that showed favorable CDC combustion conditions. In the forward flow configurations the air injection port is positioned at a location opposite to the combustor exit. The location of fuel injection ports is changed to give different configurations. The thermal intensity for the present investigation is 28MW/m3-atm simulating gas turbine conditions. Increase in thermal intensity (lower combustion volume) presents many challenges, such as, lower residence time, lower recirculation of gases and confinement effects on the jet characteristics. The results are presented on the global flame signatures, exhaust emissions, and emission of radical species using experiments and flowfield dynamics using numerical simulations. Ultra low NOx emissions are found for both the premixed and non-premixed combustion modes investigated here. The reaction zone is observed to be significantly different in different combustion modes.

Non-Premixed and Premixed Colorless Distributed Combustion for Gas Turbine Application

2010 ◽  
Author(s):  
Vaibhav Arghode ◽  
Ashwani K. Gupta
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Spontaneous Ignition ◽  
Combustion Mode ◽  
Acoustic Signatures ◽  
Combustion Modes ◽  
Sound Levels ◽  
Colorless Distributed Combustion ◽  
Gas Recirculation

Non-premixed and premixed modes of Colorless Distributed Combustion (CDC) are investigated for application to gas turbine combustors. The CDC provides significant improvement in pattern factor, reduced NOx emission uniform thermal field in the entire combustion zone for it to be called as a isothermal reactor, and lower sound levels. Basic requirement for CDC is mixture preparation through good mixing between the combustion air and product gases so that the reactants are at much higher temperature to result in hot and diluted oxidant stream at temperatures that are high enough to auto-ignite the fuel and oxidant mixture. With desirable conditions one can achieve spontaneous ignition of the fuel with distributed combustion reactions. Distributed reactions can also be achieved in premixed mode of operation with sufficient entrainment of burned gases and faster turbulent mixing between the reactants. In the present investigation two non-premixed combustion modes and one premixed combustion mode that provide potential for CDC is examined. In all the configurations the air injection port is positioned at the opposite end of the combustor exit, whereas the location of fuel injection ports is changed to give different configurations. The results are compared for global flame signatures, exhaust emissions, acoustic signatures, and radical emissions using experiments and flow field, gas recirculation and mixing using numerical simulations. Ultra low NOx emissions are observed for both the premixed and non-premixed combustion modes, and almost colorless flames (no visible flame color) have been observed for the premixed combustion mode. The non-premixed mode was also provided near colorless distributed combustion. The reaction zone is observed to be significantly different in the two non-premixed modes.

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.

Low-Nox Premixed Combustion of MBtu Fuels Using the ABB Double Cone Burner (EV Burner)

1996 ◽  
Vol 118 (1) ◽  
pp. 46-53 ◽  
Author(s):  
K. Do¨bbeling ◽  
H. P. Kno¨pfel ◽  
W. Polifke ◽  
D. Winkler ◽  
C. Steinbach ◽  
...  
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Coal Gasification ◽  
Fuel Injection ◽  
Double Cone ◽  
Premixed Combustion ◽  
Injection Method ◽  
Wide Range ◽  
Ev Burner ◽  
Combustion Technique

A novel combustion technique, based on the Double Cone Burner, has been developed and tested. NOx emissions down to very low levels are reached without the usual strong dilution of the fuel for MBtu syngases from oxygen-blown gasification of coal or residual oil. A limited amount of dilution is necessary in order to prevent ignition during the mixing of fuel and combustion air. The relevant properties of the fuel are reviewed in relation to the goal of achieving premixed combustion. The basic considerations lead to a fuel injection strategy completely different from that for natural gas. A high-speed premixing system is necessary due to the very short chemical reaction times of MBtu fuel. Fuel must be prevented from forming ignitable mixtures inside the burner for reliability reasons. A suitable fuel injection method, which can be easily added to the ABB double cone burner, is described. In common with the design of the standard EV burner, the MBtu EV burner with this fuel injection method is inherently safe against flashback. Three-dimensional flow field and combustion modeling is used to investigate the mixing patterns and the location of the reaction front. Two burner test facilities, one operating at ambient and the other at full gas turbine pressure, have been used for the evaluation of different burner designs. The full-pressure tests were carried out with the original gas turbine burner size and geometry. Combining the presented numerical predictive capabilities and the experimental test facilities, burner performance can be reliably assessed for a wide range of MBtu and LBtu fuels (residue oil gasification, waste gasification, coal gasification, etc.). The atmospheric tests of the burner show NOx values below 2 ppm at an equivalence ratio equal to full-load gas turbine operation. The NOx increase with pressure was found to be very high. Nevertheless, NOx levels of 25 vppmd (@ 15 percent O2) have been measured at full gas turbine pressure. Implemented into ABB’s recently introduced gas turbine GT13E2, the new combustion technique will allow a more straightforward IGCC plant configuration without air extraction from the gas turbine to be used.

Mixture Preparation Effects on Distributed Combustion for Gas Turbine Applications

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Ahmed E. E. Khalil ◽  
Ashwani K. Gupta ◽  
Kenneth M. Bryden ◽  
Sang C. Lee
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Hot Spot ◽  
Turbine Blades ◽  
Active Species ◽  
Low Noise ◽  
Spontaneous Ignition ◽  
Air Cooling ◽  
Nox Emissions ◽  
Mixing Process

Distributed combustion is now known to provide significantly improved performance of gas turbine combustors. Key features of distributed combustion include uniform thermal field in the entire combustion chamber for significantly improved pattern factor and avoidance of hot-spot regions that promote thermal NOx emissions, negligible emissions of hydrocarbons and soot, low noise, and reduced air cooling requirements for turbine blades. Distributed combustion requires controlled mixing between the injected air, fuel, and hot reactive gasses from within the combustor prior to mixture ignition. The mixing process impacts spontaneous ignition of the mixture to result in improved distributed combustion reactions. Distributed reactions can be achieved in premixed, partially premixed, or nonpremixed modes of combustor operation with sufficient entrainment of hot and active species present in the combustion zone and their rapid turbulent mixing with the reactants. Distributed combustion with swirl is investigated here to further explore the beneficial aspects of such combustion under relevant gas turbine combustion conditions. The near term goal is to develop a high intensity combustor with ultralow emissions of NOx and CO, and a much improved pattern factor and eventual goal of near zero emission combustor. Experimental results are reported for a cylindrical geometry combustor for different modes of fuel injection with emphasis on the resulting pollutants emission. In all the cases, air was injected tangentially to impart swirl to the flow inside the combustor. Ultra low NOx emissions were found for both the premixed and nonpremixed combustion modes for the geometries investigated here. Results showed very low levels of NO (∼10 ppm) and CO (∼21 ppm) emissions under nonpremixed mode of combustion with air preheats at an equivalence ratio of 0.6 and a moderate heat release intensity of 27 MW/m3-atm. Results are also reported on lean stability limits and OH* chemiluminescence under different fuel injection scenarios for determining the extent of distribution combustion conditions. Numerical simulations have also been performed to help develop an understanding of the mixing process for better understanding of ignition and combustion.

scholarly journals Low NOx Premixed Combustion of MBTU Fuels Using the ABB Double Cone Burner (EV Burner)

1994 ◽  
Author(s):  
K. Döbbeling ◽  
H. P. Knöpfel ◽  
W. Polifke ◽  
D. Winkler ◽  
C. Steinbach ◽  
...  
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Coal Gasification ◽  
Fuel Injection ◽  
Double Cone ◽  
Premixed Combustion ◽  
Injection Method ◽  
Wide Range ◽  
Ev Burner ◽  
Combustion Technique

A novel combustion technique, based on the Double Cone Burner, has been developed and tested. NOx emissions down to very low levels are reached without the usual strong dilution of the fuel for MBtu syngases from oxygen blown gasification of coal or residual oil. A limited amount of dilution is necessary in order to prevent ignition during the mixing of fuel and combustion air. The relevant properties of the fuel are reviewed in relation to the goal of achieving premixed combustion. The basic considerations lead to a fuel injection strategy which is completely different from that for natural gas. A high speed premixing system is necessary due to the very short chemical reaction times of MBtu fuel. Fuel must be prevented from forming ignitable mixtures inside the burner for reliability reasons. A suitable fuel injection method, which can be easily added to the ABB double cone burner, is described. In common with the design of the standard EV burner, the MBtu EV burner with this fuel injection method is inherently safe against flashback. Three dimensional flow field and combustion modelling is used to investigate the mixing patterns and the location of the reaction front. Two burner test facilities, one operating at ambient and the other at full gas turbine pressure, have been used for the evaluation of different burner designs. The full pressure tests were carried out with the original gas turbine burner size and geometry. Combing the presented numerical predictive capabilities and the experimental test facilities, burner performance can be reliably assessed for a wide range of MBtu and LBtu fuels (residue oil gasification, waste gasification, coal gasification etc.). The atmospheric tests of the burner show NOx values below 2 ppm at an equivalence ratio equal to full load gas turbine operation. The NOx increase with pressure was found to be very high. Nevertheless, NOx levels of 25 vppmd (@ 15% O2) have been measured at full gas turbine pressure. Implemented into ABB’s recently introduced gas turbine GT13E2 the new combustion technique will allow a more straightforward IGCC plant configuration without air extraction from the gas turbine to be used.

Application of Thermal Oxidation to a Recuperated Gas Turbine: The Path to PPB NOx Emissions

2013 ◽  
Author(s):  
Jeffrey Armstrong ◽  
Douglas Hamrin ◽  
Steve Lampe
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Landfill Gas ◽  
Premixed Combustion ◽  
Nox Emissions ◽  
Single Digit ◽  
Lean Premixed Combustion ◽  
Lean Premixed ◽  
Order Of Magnitude

Dry, low NOx emissions developments in the industrial gas turbine industry have focused on lean-premixed combustion to reduce NOx to single digit parts-per-million (ppmV) emissions. The reduction of thermal NOx is limited by the lowest lean-premix combustion temperatures. To overcome this limit, a thermal oxidizer is applied which can oxidize hydrocarbon fuels at temperatures below those of lean-premixed combustion in a Brayton cycle. This oxidation technique is explained in a combustion taxonomy model. This paper presents the historical development and demonstration of technology with two different recuperated gas turbines operating on landfill gas. A unique fuel-injection strategy was used to introduce the fuel into the inlet of the gas turbine’s air compressor. The technology demonstrated an order-of-magnitude reduction in the emissions of NOx to the parts-per-billion range.

Fuel Flexibility of the Alstom GT13E2 Medium Sized Gas Turbine

2008 ◽  
Author(s):  
Klaus Do¨bbeling ◽  
Thiemo Meeuwissen ◽  
Martin Zajadatz ◽  
Peter Flohr
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Fuel Injection ◽  
High Reliability ◽  
Operating Conditions ◽  
Fuel Oil ◽  
Flame Stability ◽  
Fuel Flexibility ◽  
Fuel Staging ◽  
Wobbe Index

Today’s power generation markets require considerable flexibility in terms of type and quality of fuels. However, this must be with low emissions, high reliability and high efficiency. In more than 100 installations worldwide the Alstom GT13E2 is in use with a wide variety of fuels. Fuel flexibility is the ability to burn natural gas fuels with a wide Wobbe index range which also allows the use of fuel preheaters (to increase efficiency) as well as the ability to use fuel oil as back up or main fuel. The paper will show the allowable Wobbe index range and higher hydrocarbon effects on gas turbine combustion and the field experience gained. Specific design features implemented in the GT13E2 ensure reliable and environmental friendly operation with varying fuels. Those are: 1.) an almost entirely convectively cooled combustor with only a small amount of film cooling. 2.) the use of premix burners which are stabilized by an aerodynamically induced recirculation at the centerline and a separately controlled pilot fuel injection. 3.) an adaptive fuel staging that monitors the flame stability by pulsation measurements and adjusts the fuel staging in the combustor such that the flame is always stable but not overly rich. This results in better NOx control under varying operating conditions due to the closed-loop controlled flame stability.

Swirl Effects on Distributed Combustion for Near Zero Emission Gas Turbine Application

2010 ◽  
Author(s):  
Ahmed E. E. Khalil ◽  
Vaibhav K. Arghode ◽  
Ashwani K. Gupta
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
High Heat ◽  
Spontaneous Ignition ◽  
Experimental Investigations ◽  
Diffusion Combustion ◽  
Swirl Intensity ◽  
Zero Emission ◽  
Colorless Distributed Combustion

Previous investigations of Colorless Distributed Combustion (CDC) demonstrated significant improvement in combustor’s performance. CDC is characterized by high recirculation of product gases, fast mixing, spontaneous ignition and distributed reaction, leading to avoidance of hotspots and much lower NOx emissions. In this investigation, CDC is sought with focus on tailored mixture preparation before ignition using swirl and achieving distributed combustion for developing near zero emission combustion under gas turbine combustion conditions. Numerical and experimental investigations have been performed on a cylindrical combustor. Different fuel injection and hot gases exit arrangements have been considered. Air was injected tangentially to produce vortical structure in the flow and produce high swirl intensity. Results obtained show ultra low NO emissions (∼3 PPM) at high heat release intensity of 36 MW/m3-atm at an equivalence ratio (Φ) of 0.6. The role of premixed and diffusion combustion is also examined.

Influence of Fuel Jet Momentum on Characteristics of a Reverse-Cross Flow Combustor

2017 ◽  
Author(s):  
Shreshtha Kumar Gupta ◽  
Vaibhav Arghode
Keyword(s):  
Gas Turbine ◽  
Fuel Injection ◽  
Direct Injection ◽  
Cross Flow ◽  
Pollutant Emissions ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Air Jet ◽  
Fuel Jet ◽  
Thermal Intensity

The current work is aimed towards development of high thermal intensity, low emission combustor for gas turbine engines. Employing discrete and direct injection of air and fuel in a combustion chamber and has been demonstrated to result in low pollutant emissions (NOx, CO, UHC). From our previous investigations, we found that the reverse-cross flow configuration, where air is injected from the exit end and fuel is injected in the cross flow of the injected air, results in favorable combustion and emission characteristics. Though the air jet is the dominant jet, the fuel jet can also influence the flow field, mixing and the combustion behavior inside the combustor, which is the subject of the current investigation. Here we investigate a high thermal intensity combustor relevant to gas turbine engines (at equivalence ratio of 0.8, the combustor operates at thermal intensity of 39 MW/m3-atm and heat load of 6.25 kW). Natural gas is used as the fuel and two different fuel injection diameters of 1 mm and 2 mm are investigated. This result in significantly higher (four times) fuel jet momentum from the smaller fuel injection port as compared to the larger port. From computational fluid dynamics (CFD) studies, it is observed that for the case with higher fuel jet momentum, the fuel jet deflects the air jet such that the flow pattern is significantly altered as compared to the case with lower fuel jet momentum. OH* chemiluminescece images show that the reaction zone location is significantly affected with high momentum fuel jet. NOx is reduced whereas CO is increased with higher momentum fuel jet.

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