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.

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.

Improvement of Gas Turbine Combustion Reactivity Under Flue Gas Recirculation Condition With In-Situ Hydrogen Addition

2009 ◽  
Author(s):  
Dieter Winkler ◽  
Pascal Mu¨ller ◽  
Simon Reimer ◽  
Timothy Griffin ◽  
Andre´ Burdet ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Co2 Capture ◽  
Flue Gas ◽  
Co2 Concentration ◽  
Oxygen Depletion ◽  
Hydrogen Addition ◽  
Flue Gas Recirculation ◽  
Combustion Reactivity ◽  
Gas Recirculation

Carbon Capture and Storage (CCS) solutions are currently being assessed in order to address appropriately the climate change challenge. Post-combustion CO2 capture is one of the technologies proposed for both coal-fired and gas-fired power plants. In Natural Gas Combined Cycle (NGCC), the flue gas is treated after the Heat Recovery Steam Generator (HRSG) in a so-called post-combustion CO2 capture module through use of solvents. The size of systems envisaged for the capture of CO2 scales with volumetric flow to be treated together with the CO2 concentration contained in the flue gas. Flue Gas Recirculation (FGR) is proposed as a means to increase CO2 concentration in the flue gas together with a net reduction of volumetric flow to be treated by the CO2 capture module. One of the limiting factors of this technology is the vitiation of air within gas turbine combustor and the associated reduction in oxygen concentration. This paper analyses the influence of air vitiation upon combustion in a generic premix lean industrial burner. Tests are carried out under representative inlet pressure and temperature levels. Variation of inlet oxidizer composition is simulated with the addition of nitrogen and carbon dioxide to the inlet air. It is observed that CO emission increases with oxygen depletion at a fixed residence time, signaling a reduction of combustion reactivity. In addition, NOx emission is shown to be sensitive to oxygen depletion. In order to mitigate reduction of combustion reactivity, hydrogen is added to the fuel, up to 20% in volume. As another alternative, a Catalytic Partial Oxidation (CPO) reactor is used in-situ in order to reform the fuel to different syngas blends. These syngas is then used as fuel, which enables the enhancement of the combustion reactivity counter-acting the impact of FGR conditions. The hydrogen addition appears to help improving the reactivity of the flame, making this concept relevant for operation under vitiated air condition.

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.

Modelling the Effect of External Flue Gas Recirculation on NOx and CO Emissions in a Premixed Gas Turbine Combustor With Chemical Reactor Networks

2018 ◽  
Author(s):  
V. Prakash ◽  
J. Steimes ◽  
D. J. E. M. Roekaerts ◽  
S. A. Klein
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
Recirculation Zone ◽  
Chemical Reactor ◽  
Inlet Temperature ◽  
Part Load ◽  
Flue Gas Recirculation ◽  
Reactor Networks ◽  
Gas Recirculation ◽  
The Impact

The increasing amount of renewable energy and emission norms challenge gas turbine power plants to operate at part-load with high efficiency, while reducing NOx and CO emissions. A novel solution to this dilemma is external Flue Gas Recirculation (FGR), in which flue gases are recirculated to the gas turbine inlet, increasing compressor inlet temperature and enabling higher part load efficiencies. FGR also alters the oxidizer composition, potentially leading to reduced NOx levels. This paper presents a kinetic model using chemical reactor networks in a lean premixed combustor to study the impact of FGR on emissions. The flame zone is split in two perfectly stirred reactors modelling the flame front and the recirculation zone. The flame reactor is determined based on a chemical time scale approach, accounting for different reaction kinetics due to FGR oxidizers. The recirculation zone is determined through empirical correlations. It is followed by a plug flow reactor. This method requires less details of the flow field, has been validated with literature data and is generally applicable for modelling premixed flames. Results show that due to less O2 concentration, NOx formation is inhibited down to 10–40% and CO levels are escalated up to 50%, for identical flame temperatures. Increasing combustor pressure leads to a rise in NOx due to thermal effects beyond 1800 K, and a drop in CO levels, due to the reduced chemical dissociation of CO2. Wet FGR reduces NOx by 5–10% and increases CO by 10–20%.

Exhaust Gas Recirculation Performance in Dry Low Emissions Combustors

2011 ◽  
Author(s):  
A. M. Elkady ◽  
A. R. Brand ◽  
C. L. Vandervort ◽  
A. T. Evulet
Keyword(s):  
Gas Turbine ◽  
Co2 Capture ◽  
Carbon Capture ◽  
Power Plants ◽  
Nox Reduction ◽  
Co2 Concentration ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Low Oxygen ◽  
Gas Recirculation

In a carbon constrained world there is a need for capturing and sequestering CO2. Post-combustion carbon capture via Exhaust Gas Recirculation (EGR) is considered a feasible means of reducing emission of CO2 from power plants. Exhaust Gas Recirculation is an enabling technology for increasing the CO2 concentration within the gas turbine cycle and allow the decrease of the size of the separation plant, which in turn will enable a significant reduction in CO2 capture cost. This paper describes the experimental work performed to better understand the risks of utilizing EGR in combustors employing dry low emissions (DLE) technologies. A rig was built for exploring the capability of premixers to operate in low O2 environment, and a series of experiments in a visually accessible test rig was performed at representative aeroderivative gas turbine pressures and temperatures. Experimental results include the effect of applying EGR on operability, efficiency and emissions performance under conditions of up to 40% EGR. Findings confirm the viability of EGR for enhanced CO2 capture; In addition, we confirm benefits of NOx reduction while complying with CO emissions in DLE combustors under low oxygen content oxidizer.

Investigation of a Gas Turbine Process With Reheat Combustion at Flue Gas Recirculation and Oxyfuel-Conditions

2017 ◽  
Author(s):  
Florian Beenken ◽  
Franz Joos
Keyword(s):  
Gas Turbine ◽  
Flue Gas ◽  
Co2 Sequestration ◽  
Fossil Fuels ◽  
Pressure Ratio ◽  
Electrical Power ◽  
Exhaust Gas ◽  
Power Station ◽  
Flue Gas Recirculation ◽  
Gas Recirculation

In near future electrical power generation will still be supplied by fossil fuels. To reach the targets of the conference on climate change in Paris 2015 one method proposed is the CO2 sequestration and usage or alternatively storage. Compared to coal-fired power station the amount of CO2 in the exhaust gas of gas turbine power station is much less and therefore more difficult to remove. To enhance the efficiency of the CO2-sequestration process enrichment of the CO2 in the exhaust gas could be a solution. This can be achieved by exhaust gas recirculation or by burning with pure O2 instead of air avoiding a lot of N2 in the exhaust gas, called Oxyfuel process. The work concerns to investigations of a reheat gas turbine operating with flue gas recirculation as well as with Oxyfuel operation. The thermodynamic process has been modeled in detail considering the additional demand of cooling of the combustors and the turbines at Oxyfuel process. Additional combustion experiments have been carried out with flue gas recirculation as well as with Oxyfuel conditions burning Natural Gas with O2 in a CO2 environment to investigate the flame stability and extinction limit. The thermophysical properties, like specific heat capacity and sound velocity, are strongly altered by the high content of CO2 and H2O in the fluid of the turbine as well as of the compressor. For example during Oxyfuel conditions the pressure ratio is expected to decrease to about 78% of air operation. The influence of flue gas recirculation and Oxyfuel process to the gas composition as well as to the heat transfer and exit conditions are discussed.

A Novel Approach of Retrofitting a Combined Cycle With Post Combustion CO2 Capture

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Klas Jonshagen ◽  
Nikolett Sipöcz ◽  
Magnus Genrup
Keyword(s):  
Gas Turbine ◽  
Carbon Capture ◽  
Gas Flow ◽  
Carbon Capture And Storage ◽  
Main Tool ◽  
Pressure Level ◽  
Combined Cycle ◽  
Pressurized Water ◽  
Novel Approach ◽  
Gas Turbine Exhaust

Most state-of-the-art natural gas-fired combined cycle (NGCC) plants are triple-pressure reheat cycles with efficiencies close to 60%. However, with carbon capture and storage, the efficiency will be penalized by almost 10% units. To limit the energy consumption for a carbon capture NGCC plant, exhaust gas recirculation (EGR) is necessary. Utilizing EGR increases the CO2 content in the gas turbine exhaust while it reduces the flue gas flow to be treated in the capture plant. Nevertheless, due to EGR, the gas turbine will experience a different media with different properties compared with the design case. This study looks into how the turbomachinery reacts to EGR. The work also discusses the potential of further improvements by utilizing pressurized water rather than extraction steam as the heat source for the CO2 stripper. The results show that the required low-pressure level should be elevated to a point close to the intermediate-pressure to achieve optimum efficiency, hence, one pressure level can be omitted. The main tool used for this study is an in-house off-design model based on fully dimensionless groups programmed in the commercially available heat and mass balance program IPSEPRO. The model is based on a GE 109FB machine with a triple-pressure reheat steam cycle.

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.

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.

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