Combustion of Hydrogen-Methane-Air-Mixtures in a Generic Triple Swirl Burner: Numerical Studies

2021 ◽  
Author(s):  
Neha Vishnoi ◽  
Agustin Valera-Medina ◽  
Aditya Saurabh ◽  
Lipika Kabiraj
Keyword(s):  
Hydrogen Content ◽  
Energy Demand ◽  
Combustion Process ◽  
Flow Fields ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Temperature Fields ◽  
Nox Emissions ◽  
Swirl Burner ◽  
High Hydrogen

Abstract Ever-increasing energy demand, limited non-renewable resources, requirement for increased operational flexibility, and the need for reduction of pollutant emissions are the critical factors that drive the development of next generation fuel flexible gas turbine combustors. The use of hydrogen and hydrogen-rich fuels such as syngas helps in achieving decarbonisation. However, high temperatures and flame speeds associated with hydrogen might increase the NOx emissions. Humidified combustion presents a promising approach for NOx control. Humidification inhibits the formation of NOx and also allows for operating on hydrogen and hydrogen-rich fuels. The challenge in the implementation of this technology is the combustor (burner) design, which must provide a stable combustion process at high hydrogen content and ultra-wet conditions. In the present work, we investigate the flow field and combustion characteristics of a generic triple swirl burner running on humidified and hydrogen enriched methane-air mixtures. The investigated burner consists of three co-axial co-rotating swirling passages: outer radial swirler stage, and two inner concentric axial swirler stages. Reynold’s Averaged Navier-Stokes (RANS) simulation approach has been utilized here for flow description within the burner and inside the combustor. We present the flow fields from isothermal and lean pre-mixed methane-air reactive simulations based on the characterization of velocity profiles, streamwise shear layers, temperature fields and NOx emissions. Subsequently, we investigate the effect of combustion on flow fields, and flame stabilization for hydrogen enriched methane-air mixtures as a function of hydrogen content. We also investigate the effect of humidified combustion on methane-hydrogen blends and present comparison of temperature estimations and NOx emissions.

CFD Investigation of a Lean Premixed Burner Redesign for High Hydrogen Content Syngas Operation

2015 ◽  
Author(s):  
C. Bianchini ◽  
R. Da Soghe ◽  
A. Andreini ◽  
V. Anisimov ◽  
A. Bulli ◽  
...  
Keyword(s):  
Hydrogen Content ◽  
Flame Stabilization ◽  
Operating Conditions ◽  
Lookup Table ◽  
Pollutant Emissions ◽  
Chemical Mechanism ◽  
Alternative Methods ◽  
High Hydrogen ◽  
High Hydrogen Content ◽  
Lean Premixed

The continuous challenge to develop more efficient and cleaner combustion systems for energy production, promotes the exploitation of traditional fossil fuels in alternative energy cycles capable of abating pollutant emissions. Integrated coal gasification combined cycle (IGCC) technology for instance permits to convert standard coal and other carbon based fuels into hydrogen-rich syngas. These gases are generally used to fuel standard gas turbine engines typically designed for natural gas combustion. Due to the increased propensity to flashback with high hydrogen content, lean premixed burners usually need a specific redesign to ensure adequate flow velocity at the burner exit section so as to extend lean blow out limits. However design practices for flashback prevention are far from being established especially for these unconventional fuels and it is therefore of interest to rely on CFD analysis to establish flame stabilization process and to predict incipient flashback. The purpose of this work is to assess the accuracy and reliability of a CFD methodology to describe the flame anchoring process and exhaust pollutant emissions in a high hydrogen syngas version of a standard swirled lean premixed burner which has been tested in a tubular test rig. Considered numerical setup is based on the use of the Flamelet-Generated Manifolds (FGM) method which is a good choice to combine computational efficiency and detailed chemistry modelling. This work aims at providing a first assessment of the FGM model as implemented in Fluent v15 in the framework of RANS turbulence approach. Four different operating conditions at increasing pressure levels are tested and a detailed sensitivity analysis of the combustion model is provided exploring flamelet generation parameters, turbulence-chemistry interaction closures and methods to assign progress variable variance. A specifically developed detailed chemical mechanism for H2 was implemented and used to verify NOx emission predicting capabilities of three alternative methods: lookup table generated integrating with presumed PDF, automatic reactor network model based on CFD aero-thermal solution and Fluent native NOx model. Obtained results are validated against available experimental data.

scholarly journals Combustion Optimization for Coal Fired Power Plant Boilers Based on Improved Distributed ELM and Distributed PSO

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 1036 ◽  
Author(s):  
Xinying Xu ◽  
Qi Chen ◽  
Mifeng Ren ◽  
Lan Cheng ◽  
Jun Xie
Keyword(s):  
Power Plant ◽  
Combustion Process ◽  
Optimization Method ◽  
Combustion Efficiency ◽  
Pollutant Emissions ◽  
Combustion Model ◽  
Nox Emissions ◽  
Coupling Characteristics ◽  
Learning Machine ◽  
Combustion Optimization

Increasing the combustion efficiency of power plant boilers and reducing pollutant emissions are important for energy conservation and environmental protection. The power plant boiler combustion process is a complex multi-input/multi-output system, with a high degree of nonlinearity and strong coupling characteristics. It is necessary to optimize the boiler combustion model by means of artificial intelligence methods. However, the traditional intelligent algorithms cannot deal effectively with the massive and high dimensional power station data. In this paper, a distributed combustion optimization method for boilers is proposed. The MapReduce programming framework is used to parallelize the proposed algorithm model and improve its ability to deal with big data. An improved distributed extreme learning machine is used to establish the combustion system model aiming at boiler combustion efficiency and NOx emission. The distributed particle swarm optimization algorithm based on MapReduce is used to optimize the input parameters of boiler combustion model, and weighted coefficient method is used to solve the multi-objective optimization problem (boiler combustion efficiency and NOx emissions). According to the experimental analysis, the results show that the method can optimize the boiler combustion efficiency and NOx emissions by combining different weight coefficients as needed.

Fuel Flexibility Test Campaign on a GE10 Gas Turbine: Experimental and Numerical Results

2006 ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Mangani ◽  
Stefano Cocchi ◽  
Roberto Modi
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Load Condition ◽  
Co2 Concentration ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Nox Emissions ◽  
Predictive Tool ◽  
Fuel Flexibility ◽  
Base Load

Medium- and low-LHV fuels are receiving a continuously growing interest in stationary power applications. Besides that, since in many applications the fuels available at a site can be time by time of significantly different composition, fuel flexibility has become one of the most important requirements to be taken into account in developing power systems. A test campaign, aimed to provide a preliminary assessment of a small power gas turbine’s fuel flexibility, was carried over a full-scale GE10 prototypical unit, located at the Nuovo-Pignone manufacturing site, in Florence. The engine is a single shaft, simple cycle gas turbine designed for power generation applications, rated at 11 MW electrical power and equipped with a silos-type combustor. A variable composition gas fuel was obtained by mixing natural gas with CO2 to about 40% by vol. at engine base-load condition. Tests involved two different diffusive combustion systems: the standard version, designed for operation with natural gas, and a specific system designed for low-LHV fuels. Tests performed aimed to investigate both ignition limits and combustors’ performances, focusing on hot parts’ temperatures and pollutant emissions. Regarding NOx emissions, data collected during standard combustor’s tests were matched a simple scaling law (as a function of cycle parameters and CO2 concentration in the fuel mixture), which can be used in similar applications as a NOx predictive tool. In a following step, a CFD study was performed in order to verify in detail the effects of LHV reduction on flame structure and to compare measured and calculated NOx. STAR-CD™ code was employed as main CFD solver while turbulent combustion and NOx models were specifically developed and implemented using STAR’s user-subroutine features. Both models are based on classical laminar-flamelet approach. Three different operating points were considered at base-load conditions, varying CO2 concentration (0%, 20% and 30% vol. simulated). Numerical simulations point out the flexibility of the GE10 standard combustor to assure flame stabilization even against large variation of fuel characteristics. Calculated NOx emissions are in fairly good agreement with measured data confirming the validity of the adopted models.

scholarly journals Experimental investigation of distance between v-gutters on flame stabilization and NOx emissions

2019 ◽  
Vol 23 (5 Part B) ◽  
pp. 2971-2981 ◽  
Author(s):  
Dias Umyshev ◽  
Abay Dostiyarov ◽  
Andrey Kibarin ◽  
Galya Tyutebayeva ◽  
Gaziza Katranova ◽  
...  
Keyword(s):  
Bluff Body ◽  
Flame Stabilization ◽  
Temperature Fields ◽  
Flame Stability ◽  
Bluff Bodies ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Inlet Velocity ◽  
Exhaust Gas Temperature

Blow-off performance and NOx emissions of the propane and air mixture in a rectangular combustion chamber with bluff bodies were investigated experimentally and numerically. The effects of distance between bluff bodies on NOx emissions, the blow-off limit, and exhaust gas temperature were examined. It was observed that NOx emissions are highly dependent on distance between V-gutters. The re-circulation zone behind the bluff body expands in width based on the decrease of distance between V-gutters, and expands in length with the increase of inlet velocity. The temperature fields behind the bluff body show a similar change, the temperature behind the bluff body reaches its highest when the distance between V-gutters reaches 20 mm, meaning it has better flame stability. The blow-off limit is significantly improved with the decrease of distance between V-gutters. The blow-off limit is greatly improved by reducing the distance between the V-gutters. Maximum blow-off limit of 0.11 is reached in the case of 20 mm, compared with 0.16 at 50 mm at a speed of 10 m/s.

Combustion Process Optimization Using Evolutionary Algorithm

2003 ◽  
Author(s):  
Christian Oliver Paschereit ◽  
Bruno Schuermans ◽  
Dirk Bu¨che
Keyword(s):  
Evolutionary Algorithm ◽  
Fuel Injection ◽  
Combustion Process ◽  
Flame Stabilization ◽  
Recirculation Region ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Pressure Pulsations ◽  
Mixing Properties ◽  
Conflicting Objectives

Flame stabilization in a swirl-stabilized combustor occurs in an aerodynamically generated recirculation region which is a result of vortex breakdown. The characteristics of the recirculating flow are dependent on the swirl number and on axial pressure gradients. Coupling to downstream pressure pulsations is also possible. Flame stability and emission formation depend on flow and mixing properties. The mixing properties of the investigated burner can be influenced by the position and the amount of fuel injection into the burner. The fuel injection is controlled by two different setups using (a) 8 proportional valves to adjust the mass flow for each fuel injector individually or using (b) 16 digital valves to include or exclude fuel injectors along the distribution holes. The objectives are the minimization of NOx emissions and the reduction of pressure pulsations of the flame. These two objectives are conflicting, affecting the environment and the lifetime of the combustion chamber, respectively. A multi-objective evolutionary algorithm is applied to optimize the combustion process. Each optimization run results in an approximation of the Pareto front by a set of solutions of equal quality, each representing a different compromise between the conflicting objectives. One compromise solution is selected with NOx emissions reduced by 30%, while mainaining the pulsation level of the given standard burner design. Chemiluminescence pictures of this solution showed that a more uniform distribution of heat release in the recirculation zone was achieved. The results were confirmed in high pressure single burner tests. The suggested fuel injection pattern has been successfully implemented in engines with sufficient stability margins and good operational flexibility. This paper shows the careful development process from lab scale tests to full scale pressurized tests.

Investigation of H2/CH4-Air Flame Characteristics of a Micromix Model Burner at Atmosphere Pressure Condition

2018 ◽  
Author(s):  
Xunwei Liu ◽  
Weiwei Shao ◽  
Yong Tian ◽  
Yan Liu ◽  
Bin Yu ◽  
...  
Keyword(s):  
Hydrogen Content ◽  
Gas Turbines ◽  
Turbulent Flame ◽  
Experimental Studies ◽  
Nox Emission ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
High Hydrogen ◽  
Atmosphere Pressure ◽  
Turbulent Flame Speed

For high-hydrogen-content fuel, the Micromix Combustion Technology has been developed as a potential low NOx emission solution for gas turbine combustors, especially for advanced gas turbines with high turbine inlet temperature. Compared with conventional lean premixed flames, multiple distributed slim and micro flames could lead to a lower NOx emission performance for shortening residence time of high temperature flue gas and generally a more uniform temperature distribution. This work aims at micromix flame characteristics of a model burner fueled with hydrogen blending with methane under atmosphere pressure conditions. The model burner assembly was designed to have six concentrically millimeter-sized premixed units around a same unit centrally. Numerical and experimental studies were conducted on mixing performance, flame stability, flame structure and CO/NOx emissions of the model burner. OH radical distribution by OH-PLIF and OH chemiluminescence (OH*) imaging were employed to analyze the turbulence-reaction interactions and characters of the reaction zone at the burner exit. Micromix flames fueled with five different hydrogen content H2-CH4 (60/40, 50/50, 40/60, 30/70, 0/100 Vol.%) were investigated, along with the effects of equivalence ratio and heat load. Results indicated that low NOx emissions of less than 10 ppm (@15% O2) below the exhaust temperature of 1920 K were obtained for all the different fuels. Combustion oscillation didn’t occur for all the conditions. It was found that at a constant flame temperature, the higher the hydrogen content of the fuel, the higher the turbulent flame speed and the weaker the flame lift effect. Combustion noise and NOx emissions also increase with increasing hydrogen content. The OH/OH* signal distribution indicated that a pure methane micromix flame showed a lifted and weaken distributed feature.

Flame Stabilization and Emissions of a Natural Gas/Air Ceramic Porous Burner

2008 ◽  
Vol 47-50 ◽  
pp. 105-108 ◽  
Author(s):  
Neda Djordjevic ◽  
Peter Habisreuther ◽  
Nikolaos Zarzalis
Keyword(s):  
Gas Turbines ◽  
Premixed Flames ◽  
Stability Limit ◽  
Porous Matrix ◽  
Flame Stabilization ◽  
Pollutant Emissions ◽  
Inert Material ◽  
Flame Stability ◽  
Nox Emissions ◽  
Porous Burner

Increasingly stringent regulations for limiting pollutant emissions for both aircraft and industrial gas turbines enforce further reduction of NOx emissions while maintaining flame stability. Application of premixed flames offers the possibility to reduce these emissions, but nevertheless it is strongly connected with flame instability risks. A possible solution to ensure the stability of premixed flames is to provide enhanced heat recirculation employing porous inert material. Experimental determination of flame stability and emissions of a porous burner containing a reticulate ceramic sponge structure are reported and the influence of the structural properties of the porous matrix on stable operating range was investigated. It was found, that the flame stability limit was significantly higher compared with free flame burners and nitric oxide (NOx) emissions were below 10 ppm for all cases.

Hydrogen Enrichment Effects in Gaseous Fuels on Distributed Combustion

2019 ◽  
Author(s):  
Serhat Karyeyen ◽  
Joseph S. Feser ◽  
Ashwani K. Gupta
Keyword(s):  
Oxygen Concentration ◽  
Hydrogen Content ◽  
Reaction Rates ◽  
Flame Speed ◽  
Pollutant Emissions ◽  
Pollutant Emission ◽  
Flame Stability ◽  
Limited Information ◽  
High Hydrogen ◽  
Gaseous Fuels

Abstract High intensity colorless distributed combustion has been a promising combustion technique as it enables much reduced pollutant emissions such as NO and CO, as well as more thermal uniformity, flame stability and combustion efficiency. The main requirement for achieving distributed conditions is to provide controlled entrainment of reactive hot product gases into the fresh mixture prior to ignition. In this way, the oxygen concentration is reduced, which results in lower reaction rates, promoting longer mixing times and volumetric distribution of the reaction zones. Though distributed combustion has been extensively studied for various heat loads and intensities, fuels, geometries, there is limited information related to fuel flexibility. Therefore, it is of interest to investigate hydrogen enriched gaseous fuels for greater understanding of low calorific high flame speed fuels in a distributed combustion system. Three various hydrogen content gaseous fuel (40–60% by volume) were investigated in a swirl-stabilized burner for this study, through the use of either N2 or CO2 as the diluent in order to achieve distributed conditions. The OH* chemiluminescence flame signatures were obtained in the flame front and emissions were measured from the combustor exit. The results showed that both the hydrogen concentration and diluent type considerably impacted the oxygen concentration at which transition to CDC occurred. Distributed conditions were achieved at oxygen concentrations of 10–12% with entrained N2 and 13–15% with entrained CO2 for various gaseous fuels consumed. It was determined that the transition to CDC occurred at a lower oxygen concentration for high hydrogen content fuels due to the higher flame speed of hydrogen. The flame images demonstrated that the flashback propensity of the gaseous fuels were eliminated and enhanced flame stability was achieved under the favorable CDC conditions. For NO pollutant emission, ultra-low NO level was achieved under CDC (less than 1 ppm) while CO pollutant emission decreased gradually with condition approaching distributed conditions, and then increased slightly due to the lower flammability limit and dissociation of CO2.

NOx Correlation for an Industrial 10 MW Non-Premixed Gas Turbine Combustor for High Hydrogen Fuels

2016 ◽  
Author(s):  
Daniel Kroniger ◽  
Manfred Wirsum ◽  
Atsushi Horikawa ◽  
Kunio Okada ◽  
Masahide Kazari
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Turbine ◽  
Hydrogen Content ◽  
Variable Pressure ◽  
Outlet Temperature ◽  
Nox Emissions ◽  
Gas Turbine Combustor ◽  
High Hydrogen ◽  
Operation Conditions

This paper describes a model to predict the nitric oxides (NOx) emissions for a dry non-premixed flame gas turbine combustor at full operation conditions. The NOx correlation considered the combustor pressure, the combustor outlet temperature and the fuel composition from natural gas (NG) to pure hydrogen (H2) fuel. The test data for parametrizing the model was acquired with a high pressure combustion test rig for industrial 10 MWth reverse-flow gas turbine combustors. The experimental results confirm the typical dependencies of NOx emissions. As expected, higher NOx emissions occur with increasing combustor pressure, combustor outlet temperature and hydrogen content of the fuel. The reference NOx model has been derived on the basis of physical approaches for the pressure and temperature effects. The substitution of natural gas with hydrogen is taken into account by a variable pressure exponent and a variable factor in the exponent of the exponential temperature correlation. As a result, the pressure exponent increases with increasing hydrogen. The temperature exponent factor decreases with increasing hydrogen. The model can describe the data set with limitations at high pressure and high hydrogen content fuel operation conditions.

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