Comparison of Methane and Natural Gas Combustion Behavior at Gas Turbine Conditions With Flue Gas Recirculation

2010 ◽  
Author(s):  
Dieter Winkler ◽  
Simon Reimer ◽  
Pascal Mu¨ller ◽  
Timothy Griffin
Keyword(s):  
Natural Gas ◽  
Flame Front ◽  
Gas Turbine ◽  
Flue Gas ◽  
Power Plants ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Synthetic Natural Gas ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

The efficiency and economics of carbon dioxide capture in gas turbine combined cycle power plants can be significantly improved by introducing Flue Gas Recirculation (FGR) to increase the CO2 concentration in the flue gas and reduce the volume of the flue gas treated in the CO2 capture plant [1], [2]. The maximum possible level of FGR is limited to that corresponding to stoichiometric conditions in the combustor. Reduced excess oxygen, however, leads to negative effects on overall fuel reactivity and thus increased CO emissions. Combustion tests have been carried out in a generic burner under typical gas turbine conditions with methane, synthetic natural gas (mixtures of methane and ethane) and natural gas from the Swiss net to investigate the effect of different C2+ contents in the fuel on CO burnout. To locate the flame front and to measure emissions for different residence times a traversable gas probe was designed and employed. Increasing the FGR ratio led to lower reactivity indicated by a movement of the flame front downstream. Thus, sufficient flame burnout—indicated by low emissions of unburned components (CO, UHC)—required a longer residence time in the combustion chamber. Adding C2+ or H2 to the fuel moved the flame zone back upstream and reduced the burnout time. Tests were performed for the various fuel compositions at different FGR ratios and oxidant preheat temperatures. For all conditions the addition of ethane (6 and 16% vol.) or hydrogen (20% vol.) to methane shows comparable trends. Addition of hydrogen to (synthetic) natural gas which already contains C2+ has less of a beneficial effect on reactivity and CO burnout than the addition of hydrogen to pure methane. A simple ideal reactor network based on plug flow reactors with internal hot gas recirculation was used to model combustion in the generic combustor. The purpose of such a simple model is to generate a design basis for future tests with varying operating conditions. The model was able to reproduce the trends found in the experimental investigation, for example the level of H2 required to offset the effect of oxygen depletion due to simulated FGR.

Experimental Investigation of a Fuel Flexible Generic Gas Turbine Combustor With External Flue Gas Recirculation

2014 ◽  
Author(s):  
Stefan Fischer ◽  
David Kluß ◽  
Franz Joos
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Flue Gas ◽  
Power Plants ◽  
Numerical Study ◽  
Combined Cycle ◽  
Gas Turbine Combustor ◽  
Combustion Behavior ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

Flue gas recirculation in combined cycle power plants using hydrocarbon fuels is a promising technology for increasing the efficiency of the post combustion carbon capture and storage process. However, the operation with flue gas recirculation significantly changes the combustion behavior within the gas turbine. In this paper the effects of external flue gas recirculation on the combustion behavior of a generic gas turbine combustor was experimentally investigated. While prior studies have been performed with natural gas, the focus of this paper lies on the investigation of the combustion behavior of alternative fuel gases at atmospheric conditions, namely typical biogas mixtures and syngas. The flue gas recirculation ratio and the fuel mass flow were varied to establish the operating region of stable flammability. In addition to the experimental investigations, a numerical study of the combustive reactivity under flue gas recirculation conditions was performed. Finally, a prediction of blowout limits was performed using a perfectly stirred reactor approach and the experimental natural gas lean extinction data as a reference. The extinction limits under normal (non-vitiated) and flue gas recirculation conditions can be predicted well for all the fuels investigated.

Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior

2011 ◽  
Author(s):  
Frank Sander ◽  
Richard Carroni ◽  
Stefan Rofka ◽  
Eribert Benz
Keyword(s):  
Power Plant ◽  
Co2 Capture ◽  
Flue Gas ◽  
Power Plants ◽  
Combustion Process ◽  
Combined Cycle ◽  
Flue Gas Recirculation ◽  
Overall Performance ◽  
Gas Recirculation ◽  
The Impact

The rigorous reduction of greenhouse gas emissions in the upcoming decades is only achievable with contribution from the following strategies: production efficiency, demand reduction of energy and carbon dioxide (CO2) capture from fossil fueled power plants. Since fossil fueled power plants contribute largely to the overall global greenhouse gas emissions (> 25% [1]), it is worthwhile to capture and store the produced CO2 from those power generation processes. For natural-gas-fired power plants, post-combustion CO2 capture is the most mature technology for low emissions power plants. The capture of CO2 is achieved by chemical absorption of CO2 from the exhaust gas of the power plant. Compared to coal fired power plants, an advantage of applying CO2 capture to a natural-gas-fired combined cycle power plant (CCPP) is that the reference cycle (without CO2 capture) achieves a high net efficiency. This far outweighs the drawback of the lower CO2 concentration in the exhaust. Flue Gas Recirculation (FGR) means that flue gas after the HRSG is partially cooled down and then fed back to the GT intake. In this context FGR is beneficial because the concentration of CO2 can be significantly increased, the volumetric flow to the CO2 capture unit will be reduced, and the overall performance of the CCPP with CO2 capture is increased. In this work the impact of FGR on both the Gas Turbine (GT) and the Combined Cycle Power Plant (CCPP) is investigated and analyzed. In addition, the impact of FGR for a CCPP with and without CO2 capture is investigated. The fraction of flue gas that is recirculated back to the GT, need further to be cooled, before it is mixed with ambient air. Sensitivity studies on flue gas recirculation ratio and temperature are conducted. Both parameters affect the GT with respect to change in composition of working fluid, the relative humidity at the compressor inlet, and the impact on overall performance on both GT and CCPP. The conditions at the inlet of the compressor also determine how the GT and water/steam cycle are impacted separately due to FGR. For the combustion system the air/fuel-ratio (AFR) is an important parameter to show the impact of FGR on the combustion process. The AFR indicates how close the combustion process operates to stoichiometric (or technical) limit for complete combustion. The lower the AFR, the closer operates the combustion process to the stoichiometric limit. Furthermore, the impact on existing operational limitations and the operational behavior in general are investigated and discussed in context of an operation concept for a GT with FGR.

Process Analysis of Selective Exhaust Gas Recirculation for CO2 Capture in Natural Gas Combined Cycle Power Plants Using Amines

2017 ◽  
Author(s):  
Maria Elena Diego ◽  
Jean-Michel Bellas ◽  
Mohamed Pourkashanian
Keyword(s):  
Natural Gas ◽  
Co2 Capture ◽  
Flue Gas ◽  
Power Plants ◽  
Exhaust Gas Recirculation ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Natural Gas Combined Cycle ◽  
The Cost ◽  
Gas Recirculation

Post-combustion CO2 capture from natural gas combined cycle (NGCC) power plants is challenging due to the large flow of flue gas with low CO2 content (∼3–4%vol.) that needs to be processed in the capture stage. A number of alternatives have been proposed to solve this issue and reduce the costs of the associated CO2 capture plant. This work focuses on the selective exhaust gas recirculation (S-EGR) configuration, which uses a membrane to selectively recirculate CO2 back to the inlet of the compressor of the turbine, thereby greatly increasing the CO2 content of the flue gas sent to the capture system. For this purpose, a parallel S-EGR NGCC system (53% S-EGR ratio) coupled to an amine capture plant using MEA 30%wt. was simulated using gCCS (gPROMS). It was benchmarked against an unabated NGCC system, a conventional NGCC coupled with an amine capture plant (NGCC+CCS), and an EGR NGCC power plant (39% EGR ratio) using amine scrubbing as the downstream capture technology. The results obtained indicate that the net power efficiency of the parallel S-EGR system can be up to 49.3% depending on the specific consumption of the auxiliary S-EGR systems, compared to the 49.0% and 49.8% values obtained for the NGCC+CCS and EGR systems, respectively. A preliminary economic study was also carried out to quantify the potential of the parallel S-EGR configuration. This high-level analysis shows that the cost of electricity for the parallel S-EGR system varies from 82.1–90.0 $/MWhe for the scenarios considered, with the cost of CO2 avoided being in the range of 79.7–105.1 $/tonne CO2. The results obtained indicate that there are potential advantages of the parallel S-EGR system in comparison to the NGCC+CCS configuration in some scenarios. However, further benefits with respect to the EGR configuration will depend on future advancements and cost reductions achieved on membrane-based systems.

A Novel Intake Concept for Flue Gas Recirculation to Enhance CCS in an Industrial Gas Turbine

2014 ◽  
Author(s):  
Robin C. Payne ◽  
Manuel Arias ◽  
Vassilis Stefanis
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
Carbon Capture ◽  
Low Cost ◽  
Co2 Concentration ◽  
Combined Cycle ◽  
Flue Gas Recirculation ◽  
Novel Approach ◽  
Inlet Conditions ◽  
Gas Recirculation

For the next generation of combined cycles, it is essential to not only improve the performance of a gas turbine combined cycle power plant, but also reduce its environmental impact. Flue Gas Recirculation is a useful method to increase CO2 concentration in the exhaust stream, allowing a smaller and lower cost carbon capture plant than would be required without FGR. Conventional FGR methodology requires a complex mixer with long mixing section to achieve acceptable inlet conditions for the GT compressor. A novel approach is presented, where the method of introducing the flue gas to the compressor has been substantially rethought to provide a low cost and robust FGR solution for carbon capture and sequestration applications. In this paper, CFD analysis of the flow in the intake section is used to demonstrate the operating principle of such a method, and cycle modelling calculations to compare its performance with a more conventional approach.

scholarly journals Combustion Characteristics of 0.5 MW Class Oxy-Fuel FGR (Flue Gas Recirculation) Boiler for CO2 Capture

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4333
Author(s):  
Joon Ahn ◽  
Hyouck-Ju Kim
Keyword(s):  
Natural Gas ◽  
Flue Gas ◽  
Power Plants ◽  
Fuel Combustion ◽  
Upstream Region ◽  
Exhaust Gas ◽  
Flue Gas Recirculation ◽  
Partial Load ◽  
Industrial Boilers ◽  
Gas Recirculation

A 0.5 MW class oxy-fuel boiler was developed to capture CO2 from exhaust gas. We adopted natural gas as the fuel for industrial boilers and identified characteristics different from those of pulverized coal, which has been studied for power plants. We also examined oxy-fuel combustion without flue gas recirculation (FGR), which is not commonly adopted in power plant boilers. Oxy-fuel combustion involves a stretched flame that uniformly heats the combustion chamber. In oxy-natural-gas FGR combustion, water vapor was included in the recirculated gas and the flame was stabilized when the oxygen concentration of the oxidizer was 32% or more. While flame delay was observed at a partial load for oxy-natural-gas FGR combustion, it was not observed for other combustion modes. In oxy-fuel combustion, the flow rate and flame fullness decrease but, except for the upstream region, the temperature near the wall is distributed not lower than that for air combustion because of the effect of gas radiation. For this combustion, while the heat flux is lower than other modes in the upstream region, it is more than 60% larger in the downstream region. When oxy-fuel and FGR combustion were employed in industrial boilers, more than 90% of CO2 was obtained, enabling capture, sequestration, and boiler performance while satisfying exhaust gas regulations.

scholarly journals Numerical Analysis of Turbulent Combustion in a Model Swirl Gas Turbine Combustor

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Ali Cemal Benim ◽  
Sohail Iqbal ◽  
Franz Joos ◽  
Alexander Wiedermann
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Flue Gas ◽  
Numerical Study ◽  
Mixture Fraction ◽  
Gas Turbine Combustor ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

Turbulent reacting flows in a generic swirl gas turbine combustor are investigated numerically. Turbulence is modelled by a URANS formulation in combination with the SST turbulence model, as the basic modelling approach. For comparison, URANS is applied also in combination with the RSM turbulence model to one of the investigated cases. For this case, LES is also used for turbulence modelling. For modelling turbulence-chemistry interaction, a laminar flamelet model is used, which is based on the mixture fraction and the reaction progress variable. This model is implemented in the open source CFD code OpenFOAM, which has been used as the basis for the present investigation. For validation purposes, predictions are compared with the measurements for a natural gas flame with external flue gas recirculation. A good agreement with the experimental data is observed. Subsequently, the numerical study is extended to syngas, for comparing its combustion behavior with that of natural gas. Here, the analysis is carried out for cases without external flue gas recirculation. The computational model is observed to provide a fair prediction of the experimental data and predict the increased flashback propensity of syngas.

FLOX® Combustion at High Pressure With Different Fuel Compositions

2007 ◽  
Author(s):  
Rainer Lu¨ckerath ◽  
Wolfgang Meier ◽  
Manfred Aigner
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Flue Gas ◽  
Operating Conditions ◽  
Atmospheric Conditions ◽  
Relative Temperature ◽  
Planar Laser ◽  
Gas Recirculation ◽  
First Time

In Flameless Oxidation (FLOX®) the combustion is distributed over a large volume by a high internal flue gas recirculation. This technology has been successfully used for many years in technical furnaces under atmospheric conditions with very low NOx emissions. In the work presented here, FLOX® combustion was for the first time investigated at high pressure in order to assess its applicability for gas turbine combustors. A FLOX® burner was equipped with a combustion chamber with quartz windows and installed into a high pressure test rig with optical access. The burner was operated under typical gas turbine conditions at pressure of 20 bar with thermal powers up to 475 kW. Natural gas as well as mixtures of natural gas and H2 were used as fuel. The NOx and CO emissions were recorded for the different operating conditions. OH* chemiluminescence imaging and planar laser-induced fluorescence of OH were applied in order to characterize the flame zone and the relative temperature distributions. The combustion behaviour was investigated as a function of equivalence ratio and fuel composition, and the influence of the gas inlet velocity on mixing and emissions was studied. For various operating conditions the lean extinction limits were determined.

scholarly journals Process Analysis of Selective Exhaust Gas Recirculation for CO2 Capture in Natural Gas Combined Cycle Power Plants Using Amines

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Maria Elena Diego ◽  
Jean-Michel Bellas ◽  
Mohamed Pourkashanian
Keyword(s):  
Natural Gas ◽  
Co2 Capture ◽  
Flue Gas ◽  
Power Plants ◽  
Exhaust Gas Recirculation ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Natural Gas Combined Cycle ◽  
The Cost ◽  
Gas Recirculation

Postcombustion CO2 capture from natural gas combined cycle (NGCC) power plants is challenging due to the large flow of flue gas with low CO2 content (∼3–4 vol %) that needs to be processed in the capture stage. A number of alternatives have been proposed to solve this issue and reduce the costs of the associated CO2 capture plant. This work focuses on the selective exhaust gas recirculation (S-EGR) configuration, which uses a membrane to selectively recirculate CO2 back to the inlet of the compressor of the turbine, thereby greatly increasing the CO2 content of the flue gas sent to the capture system. For this purpose, a parallel S-EGR NGCC system (53% S-EGR ratio) coupled to an amine capture plant (ACP) using monoethanolamine (MEA) 30 wt % was simulated using gCCS (gPROMS). It was benchmarked against an unabated NGCC system, a conventional NGCC coupled with an ACP (NGCC + carbon capture and storage (CCS)), and an EGR NGCC power plant (39% EGR ratio) using amine scrubbing as the downstream capture technology. The results obtained indicate that the net power efficiency of the parallel S-EGR system can be up to 49.3% depending on the specific consumption of the auxiliary S-EGR systems, compared to the 49.0% and 49.8% values obtained for the NGCC + CCS and EGR systems, respectively. A preliminary economic study was also carried out to quantify the potential of the parallel S-EGR configuration. This high-level analysis shows that the cost of electricity (COE) for the parallel S-EGR system varies from 82.1 to 90.0 $/MWhe for the scenarios considered, with the cost of CO2 avoided (COA) being in the range of 79.7–105.1 $/ton CO2. The results obtained indicate that there are potential advantages of the parallel S-EGR system in comparison to the NGCC + CCS configuration in some scenarios. However, further benefits with respect to the EGR configuration will depend on future advancements and cost reductions achieved on membrane-based systems.

Flue Gas Recirculation of the Alstom Sequential Gas Turbine Combustor Tested at High Pressure

2011 ◽  
Author(s):  
Felix Guethe ◽  
Dragan Stankovic ◽  
Franklin Genin ◽  
Khawar Syed ◽  
Dieter Winkler
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Flue Gas ◽  
Operating Conditions ◽  
Limiting Factors ◽  
Combustion System ◽  
Flue Gas Recirculation ◽  
Wide Range ◽  
Gas Recirculation ◽  
The Impact

Concerning the efforts in reducing the impact of fossil fuel combustion on climate change for power production utilizing gas turbine engines Flue Gas Recirculation (FGR) in combination with post combustion carbon capture and storage (CCS) is one promising approach. In this technique part of the flue gas is recirculated and introduced back into the compressor inlet reducing the flue gas flow (to the CCS) and increasing CO2 concentrations. Therefore FGR has a direct impact on the efficiency and size of the CO2 capture plant, with significant impact on the total cost. However, operating a GT under depleted O2 and increased CO2 conditions extends the range of normal combustor experience into a new regime. High pressure combustion tests were performed on a full scale single burner reheat combustor high-pressure test rig. The impact of FGR on NOx and CO emissions is analyzed and discussed in this paper. While NOx emissions are reduced by FGR, CO emissions increase due to decreasing O2 content although the SEV reheat combustor could be operated without problem over a wide range of operating conditions and FGR. A mechanism uncommon for GTs is identified whereby CO emissions increase at very high FGR ratios as stoichiometric conditions are approached. The feasibility to operate Alstom’s reheat engine (GT24/GT26) under FGR conditions up to high FGR ratios is demonstrated. FGR can be seen as continuation of the sequential combustion system which already uses a combustor operating in vitiated air conditions. Particularly promising is the increased flexibility of the sequential combustion system allowing to address the limiting factors for FGR operation (stability and CO emissions) through separated combustion chambers.

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