CFD Modelling of Biogas Cofiring in a Gas Turbine

2002 ◽  
Author(s):  
J. A. Lycklama a` Nijeholt ◽  
E. M. J. Komen ◽  
R. T. E. Hermanns ◽  
L. P. H. de Goey ◽  
M. C. van Beek ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Burning Velocity ◽  
Combustion Process ◽  
Combustion Model ◽  
Cfd Modelling ◽  
Combustion Chemistry ◽  
Feasible Option ◽  
Safe Limit ◽  
The Stability

Cofiring of biogas in existing gas turbines is a feasible option to reduce the consumption of natural gas. However, admixing of biogas will have an effect on the combustion process. As a consequence, the burning velocity and, therefore, the flame stability may be affected when a significant amount of biogas is mixed with the natural gas. The effect of admixing natural gas with biogas on the stability of the combustion process in lean premixed gas turbines is insufficiently known. In the present paper, a Computational Fluid Dynamics (CFD) methodology will be presented for the assessment of the safe limit of biogas cofiring in a gasturbine. An advanced Flamelet/Flamefront combustion model [1, 2, 3] and the Coherent Flame Model [4] are utilized. In both models, the detailed GRI 3.0 reaction mechanism [5] has been used to describe the combustion chemistry. The degree of mixing of fuel and air in the lean premix-burners of the gasturbine has been determined with a separate CFD model of the burners.

Design Analysis of a Micro Gas Turbine Combustion Chamber Burning Natural Gas

2012 ◽  
Author(s):  
André Perpignan V. de Campos ◽  
Fernando L. Sacomano Filho ◽  
Guenther C. Krieger Filho
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbines ◽  
Low Cost ◽  
Mixture Fraction ◽  
Combustion Model ◽  
Inlet Temperature ◽  
Gas Combustion ◽  
Micro Turbine

Gas turbines are reliable energy conversion systems since they are able to operate with variable fuels and independently from seasonal natural changes. Within that reality, micro gas turbines have been increasing the importance of its usage on the onsite generation. Comparatively, less research has been done, leaving more room for improvements in this class of gas turbines. Focusing on the study of a flexible micro turbine set, this work is part of the development of a low cost electric generation micro turbine, which is capable of burning natural gas, LPG and ethanol. It is composed of an originally automotive turbocompressor, a combustion chamber specifically designed for this application, as well as a single stage axial power turbine. The combustion chamber is a reversed flow type and has a swirl stabilized combustor. This paper is dedicated to the diagnosis of the natural gas combustion in this chamber using computational fluid dynamics techniques compared to measured experimental data of temperature inside the combustion chamber. The study emphasizes the near inner wall temperature, turbine inlet temperature and dilution holes effectiveness. The calculation was conducted with the Reynolds Stress turbulence model coupled with the conventional β-PDF equilibrium along with mixture fraction transport combustion model. Thermal radiation was also considered. Reasonable agreement between experimental data and computational simulations was achieved, providing confidence on the phenomena observed on the simulations, which enabled the design improvement suggestions and analysis included in this work.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating On Hydrogen and Natural Gas Blends

2021 ◽  
Author(s):  
Orlando Ugarte ◽  
Suresh Menon ◽  
Wayne Rattigan ◽  
Paul Winstanley ◽  
Priyank Saxena ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Combustion Model ◽  
Computational Domain ◽  
Cfd Model ◽  
Exhaust Duct ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

Abstract In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

Phenomenological Modeling of Combustion in Pre-Chamber and the Pilot Flame for Natural Gas Engines

2019 ◽  
Author(s):  
Long Liu ◽  
Xia Wen ◽  
Qian Xiong ◽  
Xiuzhen Ma
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Alternative Fuels ◽  
Gas Flow ◽  
Combustion Process ◽  
Clean Energy ◽  
Combustion Model ◽  
Flame Surface ◽  
Flow Process ◽  
Natural Gas Engines

Abstract With energy shortages and increasing environmental problems, natural gas, as a clean energy, has the advantages of cheap price and large reserves and has become one of the main alternative fuels for marine diesel engines. For large bore natural gas engines, pre-chamber spark plug ignition can be used to increase engine efficiency. The engine mainly relies on the flame ejected from the pre-chamber to ignite the mixture of natural gas and air in the main combustion chamber. The ignition flame in the main combustion chamber is the main factor affecting the combustion process. Although the pre-chamber natural gas engines have been extensively studied, the characteristics of combustion in the pre-chamber and the development of ignition flame in the main combustion chamber have not been fully understood. In this study, a two-zone phenomenological combustion model of pre-chamber spark-ignition natural gas engines is established based on the exchange of mass and energy of the gas flow process in the pre-chamber and the main combustion chamber. The basic characteristics of the developed model are: a spherical flame surface is used to describe the combustion state in the pre-chamber, and according to the turbulent jet theory, the influence of turbulence on the state of the pilot flame is considered based on the Reynolds number. According to the phenomenological model, the time when the flame starts to be injected from the pre-chamber to the main combustion chamber, and the parameters such as the length of the pilot flame are analyzed. The model was verified by experimental data, and the results showed that the calculated values were in good agreement with the experimental values. It provides an effective tool for mastering the law of flame development and supporting the optimization of combustion efficiency.

CFD Analysis of Turbec T100 Combustor at Part Load by Varying Fuels

2015 ◽  
Author(s):  
Raffaela Calabria ◽  
Fabio Chiariello ◽  
Patrizio Massoli ◽  
Fabrizio Reale
Keyword(s):  
Natural Gas ◽  
Gas Turbines ◽  
Combustion Process ◽  
Calorific Value ◽  
Operating Conditions ◽  
Liquid Fuels ◽  
Cfd Analysis ◽  
Part Load ◽  
Gaseous Fuels ◽  
Wide Range

In recent years an increasing interest is focused on the study of micro gas turbines (MGT) behavior at part load by varying fuel, in order to determine their versatility. The interest in using MGT is related to the possibility of feeding with a wide range of fuels and to realize efficient cogenerative cycles by recovering heat from exhaust gases at higher temperatures. In this context, the studies on micro gas turbines are focused on the analysis of the machine versatility and flexibility, when operating conditions and fuels are significantly varied. In line of principle, in case of gaseous fuels with similar Wobbe Index no modifications to the combustion chamber should be required. The adoption of fuels whose properties differ greatly from those of design can require relevant modifications of the combustor, besides the proper adaptation of the feeding system. Thus, at low loads or low calorific value fuels, the combustor becomes a critical component of the entire MGT, as regards stability and emissions of the combustion process. Focus of the paper is a 3D CFD analysis of the combustor behavior of a Turbec T100P fueled at different loads and fuels. Differences between combustors designed for natural gas and liquid fuels are also highlighted. In case of natural gas, inlet combustor temperature and pressure were taken from experimental data; in case of different fuels, such data were inferred by using a thermodynamic model which takes into account rotating components behavior through operating maps of compressor and turbine. Specific aim of the work is to underline potentialities and critical issues of the combustor under study in case of adoption of fuels far from the design one and to suggest possible solutions.

Prediction of Pressure Rise in a Gas Turbine Exhaust Duct Under Flameout Scenarios While Operating on Hydrogen and Natural Gas Blends

2021 ◽  
Author(s):  
Orlando Ugarte ◽  
Suresh Menon ◽  
Wayne Rattigan ◽  
Paul Winstanley ◽  
Priyank Saxena ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Combustion Process ◽  
Pressure Rise ◽  
Combustion Model ◽  
Computational Domain ◽  
Cfd Model ◽  
Exhaust Duct ◽  
Gas Turbine Exhaust ◽  
Turbine Exhaust

Abstract In recent years, there is a growing interest in blending hydrogen with natural gas fuels to produce low carbon electricity. It is important to evaluate the safety of gas turbine packages under these conditions, such as late-light off and flameout scenarios. However, the assessment of the safety risks by performing experiments in full-scale exhaust ducts is a very expensive and, potentially, risky endeavor. Computational simulations using a high fidelity CFD model provide a cost-effective way of assessing the safety risk. In this study, a computational model is implemented to perform three dimensional, compressible and unsteady simulations of reacting flows in a gas turbine exhaust duct. Computational results were validated against data obtained at the simulated conditions in a representative geometry. Due to the enormous size of the geometry, special attention was given to the discretization of the computational domain and the combustion model. Results show that CFD model predicts main features of the pressure rise driven by the combustion process. The peak pressures obtained computationally and experimentally differed in 20%. This difference increased up to 45% by reducing the preheated inflow conditions. The effects of rig geometry and flow conditions on the accuracy of the CFD model are discussed.

scholarly journals Evaluation of the possibility of the sewage sludge gasification gas use as a fuel

2016 ◽  
Vol 23 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Sebastian Werle ◽  
Mariusz Dudziak
Keyword(s):  
Sewage Sludge ◽  
Gas Turbines ◽  
Burning Velocity ◽  
Combustion Process ◽  
Laminar Burning Velocity ◽  
Gas Combustion ◽  
Reducing Atmosphere ◽  
Gasification Process ◽  
Gas Utilization ◽  
Dioxins And Furans

Abstract Biomass is one of the major sources of energy that is estimated to contribute between 10% and 14% of the world’s energy supply. Over the past several years, many societies have established policy targets to increase their production of renewable energy from biomass. The thermo-chemical utilization of biomass includes 4 technologies: the most popular combustion and co-firing, and unconventional: pyrolysis and gasification. Gasification is considered to be the perspective technology because has many advantages in comparison to traditional process of combustion: (1) limited emission of the SO2, NOx, oxides of the heavy metals and no risk of the dioxins and furans emission due to reducing atmosphere in the gasification reactor, (2) volume of the gasification gas is smaller in comparison to flue gases from combustion due to the reducing atmosphere, (3) gasification process produce gas which is potential gaseous fuel in power engineering (engines, gas turbines and boilers) and chemistry. Unfortunately, composition of the gasification gas is always described as a variable. Moreover, it depends on the conditions of the process and quality of the base fuel. For this reason, the use of gasification gas can’t be very easy. For this reason, the knowledge of the basic properties of the gas is very important. Laminar burning velocity is assumed as an important quantity for in the process of the design equipment for the gas utilization. The numerical and experimental results of the laminar burning velocity of sewage sludge gasification gases were presented. Experimental Bunsen burner method was used. Cosilab 3© software for numerical analysis was used. GRI-Mech 3.0 mechanism of gas oxidation was implemented. As a result of the work, the set of the parameters where the sewage sludge gasification gas combustion process is stable with effective heat release, were presented.

CFD Simulation of a Microturbine Annular Combustion Chamber Fuelled With Methane and Biomass Pyrolysis Syngas: Preliminary Results

2009 ◽  
Author(s):  
Francesco Fantozzi ◽  
Paolo Laranci ◽  
Michele Bianchi ◽  
Andrea De Pascale ◽  
Michele Pinelli ◽  
...  
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbines ◽  
Cfd Simulation ◽  
Combustion Process ◽  
Calorific Value ◽  
Methane Combustion ◽  
Pollutant Emissions ◽  
Preliminary Results

Micro gas turbines could be profitably used, for distributed energy production, also exploiting low calorific value biomass-derived fuels, obtained by means of integrated pyrolysis and/or gasification processes. These synthesis gases show significant differences with respect to natural gas (in terms of composition, low calorific value, hydrogen content, tar and particulate matter content) that may turn into ignition problems, combustion instabilities, difficulties in emission control and fouling. CFD simulation of the combustion chamber is a key instrument to identify main criticalities arising when using these gases, in order to modify existing geometries and to develop new generation combustion chambers for use with low calorific value gases. This paper describes the numerical activity carried out to analyze the combustion process occurring inside an existing microturbine annular combustor. A CFD study of the combustion process performed with different computational codes is introduced and some preliminary results are reported in the paper. A comparison of results obtained with the different codes is provided, for the reference case of methane combustion. A first evaluation of the pollutant emissions and a comparison with the available experimental data is also provided in the paper, showing in particular a good matching of experimental data on NOx emissions at different load conditions. Moreover, the carried out investigation concerns the case of operation with a syngas fuel derived from pyrolysis of biomass and finally the case of syngas and natural gas co-firing. This combustion condition is simulated with a simple reduced chemical kinetic scheme, in order to assess only the key issues rising with this fuel in comparison with the case of methane combustion. The analysis shows that in case of syngas operation the combustor internal temperature hot spots are reduced and the primary zone flame tends to stabilize closer to the injector, with possible implications on the emission release.

Prediction of Ultra-Lean SI Engine Performance by QD-Combustion Model With an Improved Laminar Flame Speed

2020 ◽  
Author(s):  
Ratnak Sok ◽  
Jin Kusaka ◽  
Kyohei Yamaguchi
Keyword(s):  
Gasoline Engine ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Turbulent Flame ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Flame Speed ◽  
Combustion Model ◽  
Lean Mixture ◽  
Turbulent Flame Speed

Abstract A quasi-dimensional (QD) simulation model is a preferred method to predict combustion in the gasoline engines with reliable results and shorter calculation time compared with multi-dimensional simulation. The combustion phenomena in spark ignition (SI) engines are highly turbulent, and at initial stage of the combustion process, turbulent flame speed highly depends on laminar burning velocity SL. A major parameter of the QD combustion model is an accurate prediction of the SL, which is unstable under low engine speed and ultra-lean mixture. This work investigates the applicability of the combustion model for evaluating the combustion characteristics of a high-tumble port gasoline engine operated under ultra-lean mixture (equivalence ratio up to ϕ = 0.5) which is out of the range of currently available SL functions initially developed for a single component fuel. In this study, the SL correlation is improved for a gasoline surrogate fuel (5 components). Predicted SL data from the conventional and improved functions are compared with experimental SL data taken from a constant-volume chamber under micro-gravity condition. The SL measurements are done at reference conditions at temperature of 300K, pressure of 0.1MPaa, and at elevated conditions whose temperature = 360K, pressure = 0.1, 0.3, and 0.5 MPaa. Results show that the conventional SL model over-predicts flame speeds under all conditions. Moreover, the model predicts negative SL at very lean (ϕ ≤ 0.3) and rich (ϕ ≥ 1.9) mixture while the revised SL is well validated with the measured data. The improved SL formula is then incorporated into the QD combustion model by a user-defined function in GT-Power simulation. The engine experimental data are taken at 1000 RPM and 2000 RPM under engine load IMEPn = 0.4–0.8 MPa (with 0.1 increment) and ϕ ranges are up to 0.5. The results shows that the simulated engine performances and combustion characteristics are well validated with the experiments within 6% accuracy by using the QD combustion model coupled with the improved SL. A sensitivity analysis of the model is also in good agreement with the experiments under cyclic variation (averaged cycle, high IMEP or stable cycle, and low IMEP or unstable cycle).

Temperature Distribution Analysis on Syngas Combustion in Microgas Turbine

2016 ◽  
Vol 819 ◽  
pp. 282-286
Author(s):  
Siti Sarah Ain Fadhil ◽  
Hasril Hasini ◽  
Mohd Nasharuddin Mohd Jaafar ◽  
Nor Fadzilah Othman
Keyword(s):  
Temperature Distribution ◽  
Natural Gas ◽  
Gas Turbines ◽  
Flame Temperature ◽  
Combustion Model ◽  
Base Case ◽  
Distribution Analysis ◽  
Gas Temperature ◽  
Gas Combustion ◽  
Synthetic Gas

Gas turbines are capable to utlize variety of fuel including natural gas, fuel oils and synthetic gas. It has environmental advantages and thus gas turbines are favourable in the power generating industries. The use of synthetic gas or syngas may reduce the CO2 and NOx emissions. The efficiency of syngas is comparable with natural gas. With the current constrain on the environmental issues, the use of syngas in gas turbines has been increasing. Despite its many advantages, the study on the combustion characteristics still remains a challenge, due to its variety fuel components. This paper aims to discuss the CFD analysis on the flame and flue gas temperature distribution in a full scale microgas turbine operating on syngas. Three cases were simulated with variety of natural gas concentration. A base case firing natural gas (100% methane) was first established using actual operation. Validation on the combustion model is made by comparing the flame temperature distribution of methane with reasonable accuracy. Simulation results with syngas show similar flame temperature distribution as natural gas combustion. The average temperature is much dependent on the composition of methane in syngas. The highest temperature given by syngas is made from the highest methane composiotion.

Influence of Pressure and Steam Dilution on NOx and CO Emissions in a Premixed Natural Gas Flame

2013 ◽  
Author(s):  
Sebastian Göke ◽  
Sebastian Schimek ◽  
Steffen Terhaar ◽  
Thoralf Reichel ◽  
Katharina Göckeler ◽  
...  
Keyword(s):  
Natural Gas ◽  
Scaling Laws ◽  
Combustion Process ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Nox Formation ◽  
Combustion Chemistry ◽  
Air Mass ◽  
Gas Flame ◽  
Reactor Network

In the current study, the influence of pressure and steam on the emission formation in a premixed natural gas flame is investigated at pressures between 1.5 bar and 9 bar. A premixed, swirl-stabilized combustor is developed that provides a stable flame up to very high steam contents. Combustion tests are conducted at different pressure levels for equivalence ratios from lean blowout to near-stoichiometric conditions and steam-to-air mass ratios from 0% to 25%. A reactor network is developed to model the combustion process. The simulation results match the measured NOx and CO concentrations very well for all operating conditions. The reactor network is used for a detailed investigation of the influence of steam and pressure on the NOx formation pathways. In the experiments, adding 20% steam reduces NOx and CO emissions to below 10 ppm at all tested pressures up to near-stoichiometric conditions. Pressure scaling laws are derived: CO changes with a pressure exponent of approximately −0.5 that is not noticeably affected by the steam. For the NOx emissions, the exponent increases with equivalence ratio from 0.1 to 0.65 at dry conditions. At a steam-to-air mass ratio of 20%, the NOx pressure exponent is reduced to −0.1 to +0.25. The numerical analysis reveals that steam has a strong effect on the combustion chemistry. The reduction in NOx emissions is mainly caused by lower concentrations of atomic oxygen at steam-diluted conditions, constraining the thermal pathway.

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