CFD Analysis of an Annular Micro Gas Turbine Combustion Chamber Fuelled With Liquid Biofuels: Preliminary Results With Bioethanol

2013 ◽  
Author(s):  
Paolo Laranci ◽  
Gianni Bidini ◽  
Umberto Desideri ◽  
Francesco Fantozzi
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Internal Combustion Engines ◽  
Oxidation Mechanism ◽  
Biodiesel Production ◽  
Pollutant Emissions ◽  
Cfd Analysis ◽  
Micro Gas Turbine ◽  
Preliminary Results

Liquid biofuels, such as bioethanol, biodiesel and vegetal oils, can effectively be used in internal combustion engines blended with liquid fuels of fossil origin or in their substitution, allowing a reduction of CO2 and pollutant emissions in the atmosphere. This work is supported by a CFD analysis to study the feasibility of using these fuels derived from biomass in a 80 kWel micro gas turbine, originally designed for operation with natural gas. In this paper preliminary results about the behavior of bioethanol in the MGT combustion chamber are presented. The complete investigation however includes biodiesel and also glycerin, a byproduct of biodiesel production. To carry out the computational simulations, combustion models included in a commercial software and oxidation mechanism of ethanol taken from the literature were used. The geometry of the NG injector was modified to optimize the liquid inlet into the combustor. Simulation results in terms of temperatures, pressures, and emissions were compared with data available for natural gas combustion in the original combustion chamber.

Investigation of Flame Stabilization in a High-Pressure Multi-Jet Combustor by Laser Measurement Techniques

2014 ◽  
Author(s):  
Oliver Lammel ◽  
Tim Rödiger ◽  
Michael Stöhr ◽  
Holger Ax ◽  
Peter Kutne ◽  
...  
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Recirculation Zone ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Single Shot ◽  
Optical Access

In this contribution, comprehensive optical and laser based measurements in a generic multi-jet combustor at gas turbine relevant conditions are presented. The flame position and shape, flow field, temperatures and species concentrations of turbulent premixed natural gas and hydrogen flames were investigated in a high-pressure test rig with optical access. The needs of modern highly efficient gas turbine combustion systems, i.e., fuel flexibility, load flexibility with increased part load capability, and high turbine inlet temperatures, have to be addressed by novel or improved burner concepts. One promising design is the enhanced FLOX® burner, which can achieve low pollutant emissions in a very wide range of operating conditions. In principle, this kind of gas turbine combustor consists of several nozzles without swirl, which discharge axial high momentum jets through orifices arranged on a circle. The geometry provides a pronounced inner recirculation zone in the combustion chamber. Flame stabilization takes place in a shear layer around the jet flow, where fresh gas is mixed with hot exhaust gas. Flashback resistance is obtained through the absence of low velocity zones, which favors this concept for multi-fuel applications, e.g. fuels with medium to high hydrogen content. The understanding of flame stabilization mechanisms of jet flames for different fuels is the key to identify and control the main parameters in the design process of combustors based on an enhanced FLOX® burner concept. Both experimental analysis and numerical simulations can contribute and complement each other in this task. They need a detailed and relevant data base, with well-known boundary conditions. For this purpose, a high-pressure burner assembly was designed with a generic 3-nozzle combustor in a rectangular combustion chamber with optical access. The nozzles are linearly arranged in z direction to allow for jet-jet interaction of the middle jet. This line is off-centered in y direction to develop a distinct recirculation zone. This arrangement approximates a sector of a full FLOX® gas turbine burner. The experiments were conducted at a pressure of 8 bar with preheated and premixed natural gas/air and hydrogen/air flows and jet velocities of 120 m/s. For the visualization of the flame, OH* chemiluminescence imaging was performed. 1D laser Raman scattering was applied and evaluated on an average and single shot basis in order to simultaneously and quantitatively determine the major species concentrations, the mixture fraction and the temperature. Flow velocities were measured using particle image velocimetry at different section planes through the combustion chamber.

scholarly journals A swirler stabilized combustion chamber for a micro-gas turbine fuelled with natural gas

2012 ◽  
Vol 34 (4) ◽  
pp. 441-449 ◽  
Author(s):  
Guenther C. Krieger ◽  
André P. V. de Campos ◽  
Fernando L. Sacomano Filho ◽  
Rafael C. de Souza
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Micro Gas Turbine

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.

Effects of Biogas Combustion on the Operation Characteristics and Pollutant Emissions of a Micro Gas Turbine

2003 ◽  
Author(s):  
Dieter Bohn ◽  
Joachim Lepers
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Biomass Conversion ◽  
Ceramic Materials ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Generation Process ◽  
Micro Gas Turbine ◽  
Operation Characteristics

The capability of gas turbines to burn low-BTU biogenic fuels besides natural gas becomes an increasingly important feature for small sized plants. This is particularly the case for micro gas turbines targeting decentralized applications. The energy conversion of biomass to electricity can be improved by integration of a micro gas turbine with the biogas generation process. Such an integrated plant concept is presented in this paper after a general overview of low-BTU fuels suitable for utilization in gas turbines has been given. The advantages are a more efficient biomass conversion and an extension of biomass digestion to biomass with reduced biochemical availability such as mildly lignocellulosic biomass. The effects of biogas utilization on the characteristics of operation of a representatively modeled microturbine are investigated in this paper. Particularly, contributions to the efficiency decrease occuring when biogas is burnt instead of natural gas are analyzed. Further, an overview of the effects of low-BTU fuels on gas turbine materials and pollutant emissions is given. The change of emissions of nitrogen oxide and carbon monoxide is analyzed with a combustion model based on a systematically reduced 6-step reaction mechanism. This study was conducted for an advanced combustor design applying ceramic materials and a transpiration cooling technology.

Improving Lifetime and Manufacturability of an RQL Combustor for Microturbines: Design and Numerical Validation

2015 ◽  
Author(s):  
Paolo Laranci ◽  
Gianni Bidini ◽  
Bruno D’Alessandro ◽  
Mauro Zampilli ◽  
Fabio Forcella ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Optimal Operation ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Cfd Analysis ◽  
Turbine Inlet Temperature ◽  
Micro Gas Turbine ◽  
Thermochemical Processes ◽  
Regenerated Plant

A new annular RQL combustion chamber of an 80 kWel Elliott TA80R micro gas turbine was designed and built with a modified geometry to overcome known failures at low running hours (around 2500 hrs) caused by overheating. Design considered simplified manufacturability and flow optimization to reduce emission while maintaining similar temperatures and efficiencies. A preliminary geometry was analyzed and also built to verify manufacturability and economics. It was easily built with overall brute costs around 3000 €. It has also run continuously for over 27.000 hrs. An optimized geometry, however, guaranteed similar TIT with respect to the original geometry with a considerable reduction in CO and NOx emissions. Given the installation of the mGT at the IRP (Integrated Pyrolysis Regenerated Plant) the modified geometry was tested through CFD analysis on syngas from biomass thermochemical processes. The results show that further modifications of the liner are required for optimal operation and to reach adequate values for Turbine Inlet Temperature.

Numerical Analysis of a Microturbine Combustion Chamber Modified for Biomass Derived Syngas

2011 ◽  
Author(s):  
Paolo Laranci ◽  
Edoardo Bursi ◽  
Francesco Fantozzi
Keyword(s):  
Numerical Analysis ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Combustion Process ◽  
Formation Mechanisms ◽  
Original Design ◽  
Pyrolysis Gas ◽  
Gas Combustion ◽  
Micro Gas Turbine

A CFD analysis was carried out to study the performance of a modified combustion chamber of a micro gas turbine with the objective to change its fuelling from natural gas to biomass pyrolysis gas. The micro gas turbine is a component of a pilot IPRP (Integrated Regenerated Pyrolysis Plant), a distributed energy system, based on a rotary kiln reactor for the pyrolysis of biomass. This paper describes the combustion process occurring inside the combustion chamber of the micro gas turbine. In particular, a new, revised kinetic scheme was implemented in the RANS analysis to better reproduce CO oxidation and flue gases temperature, for both methane and pyrolysis gas combustion; further investigation was undertaken on NOx formation mechanisms, which are now modeled through a non-adiabatic PPDF approach, also taking into account the effects of turbulence interaction. CFD simulations for natural gas and pyrolysis gas combustion were performed for two different annular rich-quench-lean combustion chamber configurations, one with the original design for natural gas and one with a modified design optimized for syngas, in order to quantify the advantage of using a dedicated design. Furthermore, through the numerical analysis, the hot spots of the combustor have been identified and monitored the to study the possible effects of material corrosion due to high temperatures.

A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

2021 ◽  
pp. 146808742110050
Author(s):  
Enrica Malfi ◽  
Vincenzo De Bellis ◽  
Fabio Bozza ◽  
Alberto Cafari ◽  
Gennaro Caputo ◽  
...  
Keyword(s):  
Natural Gas ◽  
Internal Combustion Engines ◽  
Pollutant Emissions ◽  
Average Error ◽  
Combustion Engines ◽  
Nitric Oxides ◽  
Lean Burn ◽  
Fuel Charge ◽  
Unburned Hydrocarbons ◽  
Model Reliability

The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/fuel charge is under development as a path to simultaneously improve thermal efficiency, fuel consumption, nitric oxides, and carbon monoxide emissions. This technology may lead to a relevant emission of unburned hydrocarbons (uHC) compared to a stoichiometric engine. The uHC sources are various and the relative importance varies according to fuel characteristics, engine operating point, and some geometrical details of the combustion chamber. This concern becomes even more relevant in the case of engines supplied with natural gas since the methane has a global warming potential much greater than the other major pollutant emissions. In this work, a simulation model describing the main mechanisms for uHC formation is proposed. The model describes uHC production from crevices and flame wall quenching, also considering the post-oxidation. The uHC model is implemented in commercial software (GT-Power) under the form of “user routine”. It is validated with reference to two large bore engines, whose bores are 31 and 46 cm (engines named accordingly W31 and W46). Both engines are fueled with natural gas and operated with lean mixtures (λ > 2), but with different ignition modalities (pre-chamber device or dual fuel mode). The engines under study are preliminarily schematized in the 1D simulation tool. The consistency of 1D engine schematizations is verified against the experimental data of BMEP, air flow rate, and turbocharger rotational speed over a load sweep. Then, the uHC model is validated against the engine-out measurements. The averaged uHC predictions highlight an average error of 7% and 10 % for W31 and W46 engines, respectively. The uHC model reliability is evidenced by the lack of need for a case-dependent adjustment of its tuning constants, also in presence of relevant variations of both engine load and ring pack design.

Numerical Investigation of an Inverted Brayton Cycle Micro Gas Turbine Based on Experimental Data

2018 ◽  
Author(s):  
Eleni Agelidou ◽  
Martin Henke ◽  
Thomas Monz ◽  
Manfred Aigner
Keyword(s):  
Experimental Data ◽  
Power Systems ◽  
Gas Turbine ◽  
Residential Buildings ◽  
Pollutant Emissions ◽  
Brayton Cycle ◽  
Single Family ◽  
Total Energy Consumption ◽  
Gas Treatment ◽  
Micro Gas Turbine

Residential buildings account for approximately one fifth of the total energy consumption and 12 % of the overall CO2 emissions in the OECD countries. Replacing conventional boilers by a co-generation of heat and power in decentralized plants on site promises a great benefit. Especially, micro gas turbine (MGT) based combined heat and power systems are particularly suitable due to their low pollutant emissions without exhaust gas treatment. Hence, the overall aim of this work is the development of a recuperated inverted MGT as heat and power supply for a single family house with 1 kWel. First, an inverted MGT on a Brayton cycle MGT was developed and experimentally characterized, in previous work by the authors. This approach allows exploiting the potential of using the same components for both cycles. As a next step, the applicability of the Brayton cycle components operated in inverted mode needs to be evaluated and the requirements for a component optimization need to be defined, both, by pursuing thermodynamic cycle simulations. This paper presents a parametrization and validation of in-house 1D steady state simulation tool for an inverted MGT, based on experimental data from the inverted Brayton cycle test rig. Moreover, a sensitivity analysis is conducted to estimate the influence of every major component on the overall system and to identify the necessary optimizations. Finally, the component requirements for an optimized inverted MGT with 1 kWel and 16 % of electrical efficiency are defined. This work demonstrates the high potential of an inverted MGT for a decentralized heat and power generation when optimizing the system components.

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.

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