Experimental and Reactor Network Study of Nitrogen Dilution Effects on NOX Formation for Natural Gas and Syngas at Elevated Pressures

2013 ◽  
Author(s):  
Ivan R. Sigfrid ◽  
Ronald Whiddon ◽  
Robert Collin ◽  
Jens Klingmann
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Central Body ◽  
Negative Impact ◽  
Flame Temperature ◽  
Fourth Generation ◽  
Atmospheric Conditions ◽  
Experimental Conditions ◽  
Wobbe Index

Gas turbines emissions, NOX in particular, have negative impact on the environment. To limit the emissions gas turbine burners are constantly improved. In this work, a fourth generation SIT (Siemens Industrial Turbomachinery) burner is studied to gain information about the formation of NOX emissions. The gas mixtures for the full burner are limited to natural gas with different nitrogen dilutions. The dilutions vary from undiluted to Wobbe index 40 and 30 MJ/m3. In addition to the full burner, the central body (the RPL – Rich/Pilot/Lean) is investigated. Methane is used to characterize standard gas turbine operation, and a non-standard fuel is explored using a generic syngas (67.5 % Hydrogen, 22.5 % Carbon monoxide and 10 % Methane). Both these gases are also investigated after dilution with nitrogen to a Wobbe index of 15 MJ/m3. The experiments are performed in a high-pressure facility. The pressures for the central body burner are 3, 6 and 9 bar. For the full burner the pressures are 3, 4.5 and 6 bar. The combustion air is preheated to 650 K. The emission measurements are sampled with an emission probe at the end of the combustor liner, and analyzed in an emission rack. The results are compared with previous investigations made at atmospheric conditions. The burner is modeled using a PSR and plug flow network to show which reaction paths are important in the formation of emissions for the burner under the experimental conditions. The measurement results show that the NOX concentration increases with pressure and flame temperature. With increasing dilution the NOX concentration is decreased. For rich mixtures PSR calculations show that the NOX concentration decreases with pressure.

scholarly journals Combustion and Oxidation Kinetics of Alternative Gas Turbines Fuels

2014 ◽  
Author(s):  
Pierre-Alexandre Glaude ◽  
Baptiste Sirjean ◽  
René Fournet ◽  
Roda Bounaceur ◽  
Matthieu Vierling ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Ignition Temperature ◽  
Alternative Fuels ◽  
Flame Temperature ◽  
Liquid Fuels ◽  
Heavy Oils ◽  
Process Gas ◽  
Auto Ignition

Heavy duty gas turbines are very flexible combustion tools that accommodate a wide variety of gaseous and liquid fuels ranging from natural gas to heavy oils, including syngas, LPG, petrochemical streams (propene, butane…), hydrogen-rich refinery by-products; naphtha; ethanol, biodiesel, aromatic gasoline and gasoil, etc. The contemporaneous quest for an increasing panel of primary energies leads manufacturers and operators to explore an ever larger segment of unconventional power generation fuels. In this moving context, there is a need to fully characterize the combustion features of these novel fuels in the specific pressure, temperature and equivalence ratio conditions of gas turbine combustors using e.g. methane as reference molecule and to cover the safety aspects of their utilization. A numerical investigation of the combustion of a representative cluster of alternative fuels has been performed in the gas phase, namely two natural gas fuels of different compositions, including some ethane, a process gas with a high content of butene, oxygenated compounds including methanol, ethanol, and DME (dimethyl ether). Sub-mechanisms have specifically been developed to include the reactions of C4 species. Major combustion parameters, such as auto-ignition temperature (AIT), ignition delay times (AID), laminar burning velocities of premixed flames, adiabatic flame temperatures, and CO and NOx emissions have then been investigated. Finally, the data have been compared with those calculated for methane flames. These simulations show that the behaviors of alternative fuels markedly differ from that of conventional ones. Especially, DME and the process gases appear to be highly reactive with significant impacts on the auto-ignition temperature and flame speed data, which justifies burner design studies within premixed combustion schemes and proper safety considerations. The behaviors of alcohols (especially methanol) display some commonalities with those of conventional fuels. In contrast, DME and process gas fuels develop substantially different flame temperature and NOx generation rates than methane. Resorting to lean premix conditions is likely to achieve lower NOx emission performances. This review of gas turbine fuels shows for instance that the use of methanol as a gas turbine fuel is possible with very limited combustor modifications.

scholarly journals CFD Modeling of Syngas Combustion and Emissions for Marine Gas Turbine Applications

2016 ◽  
Vol 23 (3) ◽  
pp. 39-49 ◽  
Author(s):  
Nader R. Ammar ◽  
Ahmed I. Farag
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Alternative Fuels ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Ansys Fluent ◽  
Gas Fuel

Abstract Strong restrictions on emissions from marine power plants will probably be adopted in the near future. One of the measures which can be considered to reduce exhaust gases emissions is the use of alternative fuels. Synthesis gases are considered competitive renewable gaseous fuels which can be used in marine gas turbines for both propulsion and electric power generation on ships. The paper analyses combustion and emission characteristics of syngas fuel in marine gas turbines. Syngas fuel is burned in a gas turbine can combustor. The gas turbine can combustor with swirl is designed to burn the fuel efficiently and reduce the emissions. The analysis is performed numerically using the computational fluid dynamics code ANSYS FLUENT. Different operating conditions are considered within the numerical runs. The obtained numerical results are compared with experimental data and satisfactory agreement is obtained. The effect of syngas fuel composition and the swirl number values on temperature contours, and exhaust gas species concentrations are presented in this paper. The results show an increase of peak flame temperature for the syngas compared to natural gas fuel combustion at the same operating conditions while the NO emission becomes lower. In addition, lower CO2 emissions and increased CO emissions at the combustor exit are obtained for the syngas, compared to the natural gas fuel.

Pentane Rich Fuels for Standard Siemens DLE Gas Turbines

2011 ◽  
Author(s):  
Mats Andersson ◽  
Anders Larsson ◽  
Arturo Manrique Carrera
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Dynamics ◽  
Heating Value ◽  
Special Adaptation ◽  
Fuel Flexibility ◽  
Combustion Properties ◽  
Model Substance ◽  
Wobbe Index

Associated gases at oil wells are often rich in heavy hydrocarbons (HHC, here denoting hydrocarbons heavier than propane). HHC cause handling difficulties and the combustion properties are quite different from standard natural gas. For this and other reasons HHC rich associated gases are often flared or vented. This is an enormous waste of useable energy and a significant contribution to emissions of pollutants, global CO2 and other greenhouse gases. Siemens Industrial Turbomachinery AB in Finspong (SIT AB) recently tested a standard DLE 25 MW SGT-600 gas turbine and a standard 31 MW SGT-700 gas turbine with HHC rich natural gas. Pentane was chosen as a model substance for HHC. The tested gases had up to 30% of the fuel heating value from pentane. The unmodified standard DLE gas turbines proved to be very tolerant to the tested pentane rich gases. CO emissions were reduced with increasing pentane content in the fuel for the same power output. NOx was observed to increase linearly with the pentane content. Combustion dynamics was affected mildly, but noticeably by the pentane rich fuel. This result, together with earlier presented results for the same DLE engines on nitrogen rich natural gases, gives an accepted and tested total LHV range of 25–50 MJ/kg and Wobbe index range of 25–55 MJ/Nm3. No special adaptation of the gas turbines was necessary for allowing this wide fuel range. The benefit of increased and proven fuel flexibility is obvious as it allows the gas turbine owner to make full use of opportunity fuels and to supply power at low fuel cost.

scholarly journals Energy and economic effects of CHP with combined technologies of corn cobs gasification and gas turbines

2016 ◽  
Vol 20 (suppl. 2) ◽  
pp. 343-354 ◽  
Author(s):  
Milana Gutesa ◽  
Branka Gvozdenac-Urosevic ◽  
Vojin Grkovic
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Energy Content ◽  
Economic Effects ◽  
Adiabatic Expansion ◽  
Corn Cob ◽  
Wobbe Index ◽  
Economic Analyses ◽  
Gas Ratio

This paper presents the performance and economic analysis of the gas turbine with co-firing gas from corn cob gasification and natural gas. Adiabatic and non-adiabatic expansion in the turbine is considered. The analysis is performed parametrically with corn cob gasification gas and natural gas ratio. The volumetric energy content of fuels with different share of gas from the corn cob gasification therefore, with different calorific values, is compared by means of the Wobbe Index. In energy and economic analyses, the following configurations are dealt with: single manifold, dual manifold and separate gas systems.

Predicting Flameholding for Hydrogen and Natural Gas Flames at Gas Turbine Premixer Conditions

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Elliot Sullivan-Lewis ◽  
Vincent McDonell
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Experimental Studies ◽  
Temperature Variations ◽  
Auto Ignition ◽  
Chamber Temperature ◽  
Transient Events ◽  
Significant Effort

Lean-premixed gas turbines are now common devices for low emissions stationary power generation. By creating a homogeneous mixture of fuel and air upstream of the combustion chamber, temperature variations are reduced within the combustor, which reduces emissions of nitrogen oxides. However, by premixing fuel and air, a potentially flammable mixture is established in a part of the engine not designed to contain a flame. If the flame propagates upstream from the combustor (flashback), significant engine damage can result. While significant effort has been put into developing flashback resistant combustors, these combustors are only capable of preventing flashback during steady operation of the engine. Transient events (e.g., auto-ignition within the premixer and pressure spikes during ignition) can trigger flashback that cannot be prevented with even the best combustor design. In these cases, preventing engine damage requires designing premixers that will not allow a flame to be sustained. Experimental studies were conducted to determine under what conditions premixed flames of hydrogen and natural gas can be anchored in a simulated gas turbine premixer. Tests have been conducted at pressures up to 9 atm, temperatures up to 750 K, and freestream velocities between 20 and 100 m/s. Flames were anchored in the wakes of features typical of premixer passageways, including cylinders, steps, and airfoils. The results of this study have been used to develop an engineering tool that predicts under what conditions a flame will anchor, and can be used for development of flame anchoring resistant gas turbine premixers.

Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine Relevant Conditions

2020 ◽  
Author(s):  
Dominik Ebi ◽  
Peter Jansohn
Keyword(s):  
Boundary Layer ◽  
Gas Turbine ◽  
Wall Temperature ◽  
Gas Turbines ◽  
High Speed ◽  
Cooling System ◽  
Atmospheric Conditions ◽  
Preheat Temperature ◽  
Swirl Burner ◽  
Wide Range

Abstract Operating stationary gas turbines on hydrogen-rich fuels offers a pathway to significantly reduce greenhouse gas emissions in the power generation sector. A key challenge in the design of lean-premixed burners, which are flexible in terms of the amount of hydrogen in the fuel across a wide range and still adhere to the required emissions levels, is to prevent flame flashback. However, systematic investigations on flashback at gas turbine relevant conditions to support combustor development are sparse. The current work addresses the need for an improved understanding with an experimental study on boundary layer flashback in a generic swirl burner up to 7.5 bar and 300° C preheat temperature. Methane-hydrogen-air flames with 50 to 85% hydrogen by volume were investigated. High-speed imaging was applied to reveal the flame propagation pathway during flashback events. Flashback limits are reported in terms of the equivalence ratio for a given pressure, preheat temperature, bulk flow velocity and hydrogen content. The wall temperature of the center body along which the flame propagated during flashback events has been controlled by an oil heating/cooling system. This way, the effect any of the control parameters, e.g. pressure, had on the flashback limit was de-coupled from the otherwise inherently associated change in heat load on the wall and thus change in wall temperature. The results show that the preheat temperature has a weaker effect on the flashback propensity than expected. Increasing the pressure from atmospheric conditions to 2.5 bar strongly increases the flashback risk, but hardly affects the flashback limit beyond 2.5 bar.

Numerical and Experimental Investigations of the Siemens SGT-800 Burner Fitted to a Water Rig

2017 ◽  
Author(s):  
Daniel Moëll ◽  
Daniel Lörstad ◽  
Annika Lindholm ◽  
David Christensen ◽  
Xue-Song Bai
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Concentration Field ◽  
Simulation Method ◽  
Experimental Investigations ◽  
High Concentration ◽  
Air Mixing ◽  
Les Model ◽  
Gas Turbine Burner

DLE (Dry Low Emission) technology is widely used in land based gas turbines due to the increasing demands on low NOx levels. One of the key aspects in DLE combustion is achieving a good fuel and air mixing where the desired flame temperature is achieved without too high levels of combustion instabilities. To experimentally study fuel and air mixing it is convenient to use water along with a tracer instead of air and fuel. In this study fuel and air mixing and flow field inside an industrial gas turbine burner fitted to a water rig has been studied experimentally and numerically. The Reynolds number is approximately 75000 and the amount of fuel tracer is scaled to represent real engine conditions. The fuel concentration in the rig is experimentally visualized using a fluorescing dye in the water passing through the fuel system of the burner and recorded using a laser along with a CCD (Charge Couple Device) camera. The flow and concentration field in the burner is numerically studied using both the scale resolving SAS (Scale Adaptive Simulation) method and the LES (Large Eddy Simulation) method as well as using a traditional two equation URANS (Unsteady Reynolds Average Navier Stokes) approach. The aim of this study is to explore the differences and similarities between the URANS, SAS and LES models when applied to industrial geometries as well as their capabilities to accurately predict relevant features of an industrial burner such as concentration and velocity profiles. Both steady and unsteady RANS along with a standard two equation turbulence model fail to accurately predict the concentration field within the burner, instead they predict a concentration field with too sharp gradients, regions with almost no fuel tracer as well as regions with far too high concentration of the fuel tracer. The SAS and LES approach both predict a more smooth time averaged concentration field with the main difference that the tracer profile predicted by the LES has smoother gradients as compared to the tracer profile predicted by the SAS. The concentration predictions by the SAS model is in reasonable agreement with the measured concentration fields while the agreement for the LES model is excellent. The LES shows stronger fluctuations in velocity over time as compared to both URANS and SAS which is due to the reduced amounts of eddy viscosity in the LES model as compared to both URANS and SAS. This study shows that numerical methods are capable of predicting both velocity and concentration in a gas turbine burner. It is clear that both time and scale resolved methods are required to accurately capture the flow features of this and probably most industrial DLE gas turbine burners.

scholarly journals Natural Gas

2011 ◽  
Vol 133 (04) ◽  
pp. 52-52
Author(s):  
Rainer Kurz
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Oil And Gas ◽  
Electrical Power ◽  
Offshore Platforms ◽  
Electric Motors ◽  
Turbine Generator ◽  
Associated Gas ◽  
Generator Sets

This article discusses the importance of gas turbines, centrifugal compressors and pumps, and other turbomachines in processes that bring natural gas to the end users. To be useful, the natural gas coming from a large number of small wells has to be gathered. This process requires compression of the gas in several stages, before it is processed in a gas plant, where contaminants and heavier hydrocarbons are stripped from the gas. From the gas plant, the gas is recompressed and fed into a pipeline. In all these compression processes, centrifugal gas compressors driven by industrial gas turbines or electric motors play an important role. Turbomachines are used in a variety of applications for the production of oil and associated gas. For example, gas turbine generator sets often provide electrical power for offshore platforms or remote oil and gas fields. Offshore platforms have a large electrical demand, often requiring multiple large gas turbine generator sets. Similarly, centrifugal gas compressors, driven by gas turbines or by electric motors are the benchmark products to pump gas through pipelines, anywhere in the world.

Experimental Investigation of the Impact of Biogas on a 3 kW Micro Gas Turbine FLOX®-Based Combustor

2020 ◽  
Author(s):  
Hannah Seliger-Ost ◽  
Peter Kutne ◽  
Jan Zanger ◽  
Manfred Aigner
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Waste Heat ◽  
Electrical Power ◽  
Atmospheric Conditions ◽  
Micro Gas Turbine ◽  
Fuel Mixtures ◽  
Carbon Dioxide Co2 ◽  
Electrical Power Output ◽  
The Impact

Abstract The use of biogas has currently two disadvantages. Firstly, processing biogas to natural gas quality for feeding into the natural gas grid is a rather energy consuming process. Secondly, the conversion into electricity directly in biogas plants produces waste heat, which largely cannot be used. Therefore, a feed-in of the desulfurized and dry biogas to local biogas grids would be preferable. Thus, the biogas could be used directly at the end consumer for heat and power production. As biogas varies in its methane (CH4) and carbon dioxide (CO2) content, respectively, this paper studies the influence of different biogas mixtures compared to natural gas on the combustion in a FLOX®-based six nozzle combustor. The single staged combustor is suitable for the use in a micro gas turbine (MGT) based combined heat and power (CHP) system with an electrical power output of 3 kW. The combustor is studied in an optically accessible atmospheric test rig, as well as integrated into the MGT system. This paper focuses on the influence of the admixture of CO2 to natural gas on the NOX and CO emissions. Furthermore, at atmospheric conditions the shape and location of the heat release zone is investigated using OH* chemiluminescence (OH* CL). The combustor could be stably operated in the MGT within the complete stationary operating range with all fuel mixtures.

Thermodynamic Rationale for Using Expander-Compressor Gas Turbine Power Unit

2021 ◽  
pp. 166-184
Author(s):  
A.S. Strebkov ◽  
A.V. Osipov ◽  
S.V. Zhavrotskiy
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Power Unit ◽  
Thermal Cycle ◽  
Turbine Unit ◽  
Negative Impact ◽  
Excess Pressure ◽  
Electricity Production ◽  
Gas Turbine Unit ◽  
Energy Potential

Natural gas is transported through a network of main gas pipelines under high pressure, and the process of its consumption requires a decrease in pressure of gas laid mainly in throttling devices. It is beneficial to use part of the available energy potential of natural gas for electricity production by means of expander-generator technologies. However, the task of finding ways to increase the capacity and efficiency of gas turbine power units using the energy of excess pressure of natural gas does not lose its relevance. The study poses and solves the problem of developing a new thermal cycle diagram of a combined power unit to substitute throttling pressure regulators at gas distribution stations with an expander-compressor gas turbine unit. A distinctive feature of the unit is the replacement of the gas turbine drive of the air compressor with its drive from the turbo-expander by using the energy of excess pressure of natural gas. This results in significant increase in the absolute thermal efficiency and decrease in the specific fuel and energy costs. We developed analytical dependencies relating the operating parameters of the expander-compressor gas turbine unit and its output characteristics. Thus, it was possible to find an approach to calculating the unit, the approach being based on proven methods for thermal cycle calculation. The results of the performed calculations show that, in comparison with gas turbine units, the expander-compressor gas turbine unit has a significantly lower specific consumption of equivalent fuel and a lower negative impact on the environment

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