Industrial Burner Research Articles

Experimental Determination of a Mixture Composed of Camisea Natural Gas and CO2 Laminar Burning Velocity

The aim of this work is to provide new experimental data on laminar burning velocities for a new synthetic mixture composed of Camisea natural gas and CO2. It was found that the relevant published experimental background data are l imited to mixtures composed of methane and CO2; considering the fact that Camisea natural gas is widely used in Peru, this experimental research will serve as a supportive resource for further experimental and industrial implementations in this country, such as the design and modeling of new engines or industrial burners that are designed to be fueled by this mixture. An experimental setup for analyzing three types of flame geometry, which is feasible to implement for a wide range of conditions, was built in PUCP PI0735 laboratory and all the measurements were obtained for a range of mixtures (0%, 21.2%, 28.5%, 38.9%, 50% CO2) and ratios from around 0.55 to 0.95 at atmospheric conditions. The laminar burning velocities results obtained were analyzed in groups based on %CO2. In addition, the experimental margin error was determined by considering all the sources. The following conclusions were reached: (1) The laminar burning velocity decreases with the increase in CO2 percentage in the mixture due to the CO2 decreasing the flame temperature effect. (2) The flat flame type provided the highest value of burning velocity for each group of CO2 percentage in which it appears. (3) The highest obtained laminar burning velocity value was 22.64 ± 0.15 cm/s, for a flat flame with a ratio of 0.72 and 29.98% of CO2, while the lowest obtained value was 6.78 ± 0.15 cm/s for a conical trunk flame with a ratio of 0.59 and 49.83% of CO2. (4) The highest evaluated CO2 percentage was 50.97% for a conical trunk flame with a ratio of 0.69 and a burning velocity value of 11.04.

Equivalence Ratio-Driven Flame Response of an Industrial Premixed Burner: Experiments and Modeling

Abstract This paper presents an analysis of the unsteady heat release rate response of premixed flames to equivalence ratio perturbations for an industrial premixed swirl-based burner. During this investigation, perfectly and technically premixed flames were acoustically forced via fuel/air mixture flow and air flow modulations, respectively, at the same operating conditions. From the resulting flame transfer functions (FTFs), measured using the multimicrophone method, the equivalence ratio driven FTF was isolated and extracted by removing the velocity driven component, i.e., the measured FTF from the perfectly premixed flame, from the technically premixed FTF with two novel extraction techniques. The results are compared with FTFs obtained directly in a previous experimental campaign where the fuel flow was acoustically forced, the resulting equivalence ratio fluctuations measured via an infrared absorption technique, and the heat release rate response to the forcing was quantified using chemiluminescence measurements. The results from both measurement approaches agreed well highlighting the validity of the techniques. Further, to understand the governing features of the equivalence ratio driven FTF, a physics-based analytical model following the G-equation approach was developed. The contributions from flame surface area, flame speed, and heat of reaction oscillations were modeled to describe the heat release rate dynamics. A limited number of physical parameters in the analytical model were anchored on one test condition, optimized and restricted to values, which were all physically reasonable, and were subsequently used for model predictions at other operating conditions. The FTF model predictions compared well with experimental data across a range of different operating conditions. Finally, the relative contributions from flame surface area, flame speed, and heat of reaction oscillations on the features of the FTFs were identified and explored.

Hydrogen in Burners: Economic and Environmental Implications

For centuries, fossil fuels have been the primary energy source, but their unchecked use has led to significant environmental and economic challenges that now shape the global energy landscape. The combustion of these fuels releases greenhouse gases, which are critical contributors to the acceleration of climate change, resulting in severe consequences for both the environment and human health. Therefore, this article examines the potential of hydrogen as a sustainable alternative energy source capable of mitigating these climate impacts. It explores the properties of hydrogen, with particular emphasis on its application in industrial burners and furnaces, underscoring its clean combustion and high energy density in comparison to fossil fuels, and also examines hydrogen production through thermochemical and electrochemical methods, covering green, gray, blue, and turquoise pathways. It discusses storage and transportation challenges, highlighting methods like compression, liquefaction, chemical carriers (e.g., ammonia), and transport via pipelines and vehicles. Hydrogen combustion mechanisms and optimized burner and furnace designs are explored, along with the environmental benefits of lower emissions, contrasted with economic concerns like production and infrastructure costs. Additionally, industrial and energy applications, safety concerns, and the challenges of large-scale adoption are addressed, presenting hydrogen as a promising yet complex alternative to fossil fuels.

Prediction of the Flame Characteristics of an Industrial Gas Turbine Operated With CO2-Diluted Air Through a High-Fidelity Numerical Analysis: A Comparison Between Flamelet Generated Manifolds and Artificially Thickened Flame

Abstract In light of the global commitment to decarbonize industrial processes, carbon capture and storage (CCS) plays a pivotal role in mitigating greenhouse gas emissions from gas turbine (GT) power generation processes. Achieving an efficient GT–CCS coupling requires the employment of high percentages of exhaust gas recirculation (EGR) to maximize the CO2 content at the CCS inlet. Nevertheless, such operating conditions pose critical challenges for conventional combustion systems due to reduced oxygen levels associated with higher EGR, limiting engine operability. To address this challenge, the development of innovative technical solutions is essential to extend the combustor operational capabilities at high EGR rates. For this goal, a significant number of computational fluid dynamics (CFD) simulations are required to identify the flame stability limits across various EGR levels and burner designs. It is imperative, in this context, to minimize computational costs while maintaining high accuracy. In this work, a comprehensive comparative study of an extended version of the flamelet generated manifolds (FGM) and the artificially thickened flame (ATF) model is performed through a large eddy simulation (LES)-based CFD analysis. The investigation is performed within the context of an industrial lean-premixed burner manufactured by Baker Hughes, operating with natural gas and CO2-diluted air at atmospheric pressure. While the extended-FGM has been previously presented by the authors in a study on the same test rig under standard air conditions, the current work aims to extend its application to critical oxygen-depleted conditions, where near-blowout phenomena such as flame liftoff and length elongation may become significantly pronounced. Numerical validation is carried out through a direct comparison of the computed averaged heat release, representing the flame topology, with detailed OH* chemiluminescence images from a test campaign conducted by the technology for high temperature (THT) Lab of the University of Florence. The experimental data will serve as the primary benchmark for assessing the models’ effectiveness in capturing the main dynamics of such critical operating conditions. Furthermore, potential disparities in both thermal and flow fields at the burner exit region between the two models will be discussed.

Thickened Flame Model Extension for Dual Gas Turbine Combustion: Validation Against Single Cup Atmospheric Test

Abstract The development of predictive combustion models is more and more strategic in the design definition of gas turbine (GT) combustor. The thickened flame model (TFM), despite its high computational cost, is one of the most accurate approach available in literature since it can naturally take into account the nonequilibrium effects into the flame brush (i.e., strain and heat losses) as well as preferential diffusion when hydrogen is employed. Conversely, the original formulation of this combustion model needs several adjustments to accommodate the properties of the mixture when different streams of fuels and/or oxidizers are present in the system. The present work represents a first step in the extension of this combustion model to handle multiple streams of fuels and oxidizers. More specifically, an industrial burner fed with two different fuel streams and air as oxidizer is considered. The pilot fuel line is fed with microhydrogen injections with the aim to enhance the lean blow-out margin, while the main one is with pure methane. Dedicated tests are performed at the Technology for High Temperature laboratory (University of Florence) to retrieve the main information characterizing the burner (emissions, temperature, and pressure pulsations) as well as OH* chemiluminescence for the flame shape and position at the same operating conditions. The comparison between the numerical results and the experimental data will provide highlights about the ability of the extended-TFM to capture the main features of the flame stabilization mechanisms.

Passive control of thermoacoustic instability in a high-efficiency domestic gas stove with fine-tuning burner

Thermoacoustic oscillation is a significant challenge in the development of advanced thermal power and propulsion systems. The present work focuses on the whistling phenomenon in the practical burners of a developing high-efficiency domestic gas stove. The acoustic analysis is conducted by a Helmholtz acoustic solver, identifying the 1/2 wave longitudinal mode in the outer ring or center nozzle and its upstream pipe and estimating the modal eigenfrequencies fa=599Hz and fb=647Hz which are close to the main frequency of the whistling measured in experiments. The sequential flame images captured by a high-speed camera are processed by a dynamic mode decomposition method to illustrate flame structure oscillations at the peak frequency mode. The results verify that thermoacoustic oscillations are the generation mechanism of the whistling and display the periodic fluctuation characteristics of the flame and the spatial distribution of heat release. Moreover, both structural fine-tuning designs help to achieve better suppression for thermoacoustic oscillations and avoid the whistling phenomenon. These structural fine-tuning strategies have been researched for several decades but rarely reported to be applied to industrial burners in previous work. Motivated by this, it will provide a new insight into the investigation of burner structures on thermoacoustic behaviors and the application of these passive control strategies.

A repetitive pulsed electrothermal plasma jet ignition system based on capillary discharge.

Plasma ignition and combustion enhancement is a promising technology in applications of engines, industrial burners, pollutant emissions controls, etc. A new repetitive electrothermal plasma jet ignition system based on ablated capillary discharge under atmospheric pressure is presented in this paper. It consists of a capillary discharge module, a pulse current circuit, a pulse voltage circuit, a current release unit, an LC series resonant circuit, and a control system. The effects of the energy storage capacitor's voltage and resistance in the current release unit on the electrical parameters are investigated. Increasing the capacitor voltage helps to shorten the discharge delay and increase the energy deposition efficiency in the main discharge process. The increase of the resistance in the current release unit leads to a longer discharge delay and higher energy deposition efficiency in the main discharge process. Balanced parameters between the delay of discharge in 66 µs and the energy deposition efficiency in 84% are achieved through optimization, with a peak radiative heat flux of 23MWm-2 and a maximum jet length of 17cm. Repetitive capillary discharge at 20Hz under atmospheric pressure is achieved with the dispersion of energy storage capacitor charging voltage and energy deposition efficiency of 0.3% and 9.6%, respectively. Simplified circuit topology and control logic contribute to the miniaturization of the ignition system.

Industrial Decarbonization through Blended Combustion of Natural Gas and Hydrogen

The transition to cleaner energy sources, particularly in hard-to-abate industrial sectors, often requires the gradual integration of new technologies. Hydrogen, crucial for decarbonization, is explored as a fuel in blended combustions. Blending or replacing fuels impacts combustion stability and heat transfer rates due to differing densities. An extensive literature review examines blended combustion, focusing on hydrogen/methane mixtures. While industrial burners claim to accommodate up to 20% hydrogen, theoretical support is lacking. A novel thermodynamic analysis methodology is introduced, evaluating methane/hydrogen combustion using the Wobbe index. The findings highlight practical limitations beyond 25% hydrogen volume, necessitating a shift to “totally hydrogen” combustion. Blended combustion can be proposed as a medium-term strategy, acknowledging hydrogen’s limited penetration. Higher percentages require burner and infrastructure redesign.

The Impact of Incorporating Varying Proportions of Sugar Beet Waste on the Combustion Process and Emissions in Industrial Burner Fuelled with Conventional Diesel Fuel

Abstract The main objective of the case study is to investigate the effectiveness of using solid fuel additives in conventional diesel fuel for industrial furnaces. The study focuses on utilizing agricultural waste derived from sugar beet plant waste as additives to enhance the combustion process and reduce emissions from industrial burners. In this study, experimental measurent for the flame temperatures inside the furnace while altering the proportions of the solid materials have ben achived. The goal was to assess the impact of different loading from these additives on the combustionprocess. Furthermore, the study involved measuring exhaust gases such as carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbon (UH), and nitrogen oxides (NOx). The experimental facility arranment allowed the researchers to evaluate the emissions resulting from the combustion process with the addition of solid fuel additives. By measuring these parameters, the study aimed to understand the effect of utilizing agricultural waste as additives on the burning processes and emission formation in industrial furnaces. These findings can contribute to improving the efficiency of combustion processes, reducing emissions, and promoting the utilization of renewable and sustainable fuel sources in industrial settings. In this study, varying the proportions of solid materials used as additives had an impact on the levels of carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOx) in the exhaust gases. By increasing the proportion of solid materials in the fuel mixture resulted in changes in the emission levels. The levels of carbon monoxide in the exhaust gases decreased as the proportion of solid materials increased. While the addition of solid fuel additives did contribute to the production of CO2 due to the combustion of the additives, the overall effect on its levels varied depending on the specific proportions used. Also, the levels of nitrogen oxides in the exhaust gases showed different trends depending on the proportions of solid materials used. Typically, increasing the proportion of solid fuel additives led to reduce NOx emissions. However, this may also depend on other factors such as combustion temperature and the composition of the solid materials.

Numerical and experimental analysis of the formation of nitrogen oxides in a non-premixed industrial gas burner

Nitrogen oxides (NOx) formation in a non-premixed industrial gas burner is analyzed with Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics, using the Flamelet Generated Manifold (FGM) approach for chemistry and the Reynolds stress model for turbulence closure. Analysis and validation of the numerical methodology use both the RANS and the Large Eddy Simulation methods to study the Sandia flame D experiment. Four regimes of the gas burner, differing by thermal power, are studied experimentally and numerically, comparing measured and computed flue gas temperature and emissions. The flow features leading to NOx formation are analyzed. At low power, most NOx formation occurs in the flame core, where temperatures are highest. At high power, a significant amount of NOx forms where a secondary stream of oxidizer meets the high-temperature burnt gas stream. The NOx formation rate is modeled either by summing the contributions of the main paths relevant to the studied problem or via two variants of the FGM scalar transport approach. One of these variants features a correction to the transported scalar approach that enables accounting for the effects of non-adiabatic phenomena, e.g. heat radiation, on NOx formation without increasing the look-up table dimensionality and the required memory usage. The correction is shown to improve emission predictions over the baseline model, although quantitative differences between predicted and measured emission levels remain significant. The approach computing the NOx formation rate as by summing contributions yields the best agreement with measurements when the thermal path predominates, and the formation of nitrogen dioxide is negligible.

Investigation of differential diffusion in lean, premixed, hydrogen-enriched swirl flames

Hydrogen combustion is a promising alternative to fossil fuel combustion in an effort to reduce our carbon footprint. However, hydrogen combustion is prone to thermodiffusive instabilities largely dependent on differential diffusion, a phenomenon that can lead to higher probabilities of flashback in industrial burners, given hydrogen’s high reactivity and diffusivity. This paper evaluates low-swirl flames of methane and air enriched with hydrogen to highlight the onset of differential diffusion. Testing was conducted in a fully controllable swirl burner, where bulk velocity Uav = 13 m/s and swirl number S = 0.6 were kept constant for each hydrogen–methane blend to isolate increases in flame surface area from increases in turbulence intensity. Furthermore, each fuel blend of hydrogen and methane is evaluated at the same laminar flame speed of SLo = 0.267 m/s to isolate flame stretch effects on the turbulent burning rate. Combined hydroxyl (OH) PLIF and stereoscopic PIV at the National Research Council of Canada were used to analyze the OH fluorescence in a 2D-3C velocity field for each flame condition. High-speed PIV at McGill University was used to resolve local flame phenomena, such as local flame displacement velocity and flame stretch rate. Using these techniques, it can be observed that the flame displaces axially in response to turbulent flame speed while exhibiting increases in flamefront wrinkling. This increased corrugation due to flame stretch is highlighted in the PDFs of local curvature and κSf and is further evidenced by a shift towards positive curvatures (κ> 0) for increasing H2 volume fraction. This trend suggests that there is a strong correlation with increases in turbulent burning rate and positive curvature as a result of differential diffusion, but it is not necessarily a control mechanism of the most forward propagating points proposed by the theory of leading points.

Numerical investigation of methane-air jet flame with hydrogen addition in industrial kiln burners

Emission reduction and decarbonisation in the industry are crucial for low-carbon industry and energy transition at the global level. Replacing traditional fossil fuel with clean energy is an effective approach to reduce carbon emissions and optimize energy efficiency in manufacturing processes. Industrial kiln, which requires high natural gas fuel consumption, typically releases amounts of harmful combustion products. In this paper, the objective is to study the influence of hydrogen addition into methane-air jet flame in industrial kiln burners. The industrial burner analysed in this study is a cylinder vessel with axial orifices and swirl turbulent co-flow air jets in the fuel-air inlet structure. A more recent reduced chemical kinetic mechanism for methane-hydrogen combustion is utilized in the present flame simulation and validated in benchmark flames. The chemical mechanism involves 45 reactions and 18 species. Various methane-hydrogen blending fuels are studied in the jet flame, where flame structure and flame characteristics including chemical species, temperature, and velocity are predicted.

Numerical simulation of an industrial radiant tube burner using OpenFOAM

This study presents a numerical investigation into the effects of physical models on the prediction accuracy of the wall temperature distribution in an industrial radiant tube burner. Utilizing a reacting flow solver based on OpenFOAM, we explored the effects of various physical models, including those for chemistry, combustion, heat transfer, and radiation properties. The choice of combustion model significantly influences prediction accuracy, playing a more dominant role than the chemistry mechanism. Moreover, the simulations captured a distinctive triple flame structure inside the burner, representing the coexistence of rich premixed, non-premixed, and lean premixed flame structures. Conditional scatter plots displayed the development of both premixed and non-premixed flame structures, converging on the fuel-lean side. Notably, accurate prediction of wall temperature distribution depends on the incorporation of a precise heat transfer model, coupled with a detailed radiation property model. Regarding the distribution of tube surface temperature in the main radiation zone (a distance from the burner nozzle greater than 1 m), the most accurate prediction exhibits a maximum deviation of less than 56 K and an average deviation of 24 K compared to experimental results. The simulation closely matched experimental data for exhaust concentration of NO within an error margin of 20 ppm. However, discrepancy was observed in the CO concentration, which was attributed to the simplified representations of fuel chemistry and composition, as well as the difficulties in accurately capturing the unsteady flame dynamics near the wall.

FGM vs ATF: A comparative LES analysis in predicting the flame characteristics of an industrial lean premixed burner for gas turbine applications

In the pursuit of decarbonization, the reduction of greenhouse gas emissions from power generation through gas turbine (GT) engines plays a crucial role in the whole industrial sector. As industries strive to transition towards cleaner energy sources, the design and optimization of novel GT burners require a deep comprehension of the complex interaction between fluid dynamics and combustion processes embedded within the system. Computational Fluid Dynamics (CFD) plays a pivotal role in these processes by providing valuable insights into the complex flow patterns, flame topology, and stability limits within the combustor. Concurrently, the burner design phase necessitates a considerable number of simulations to ascertain flame stability limits under various burner designs and operating conditions. Therefore, it is imperative to control computational costs while ensuring a high level of accuracy. The present work is focused on a comprehensive comparative analysis of two widely employed turbulent combustion closure models: the Flamelet Generated Manifold (FGM) and the Artificially Thickened Flame (ATF). Both models utilize extended versions with specific modifications aimed at effectively addressing their respective limitations. The investigation is performed through a Large Eddy Simulation (LES) based CFD analysis within the context of a lean premixed burner designed by Baker Hughes and operated with methane at atmospheric pressure. The primary benchmark for numerical validation will be provided by detailed chemiluminescence images from a test campaign conducted by the University of Florence, thereby yielding valuable insights into flame topology and positioning. Furthermore, potential disparities in the flow field and fuel concentration at the burner exit between the two models will be revealed.

Experimental characterization of an industrial burner operated with simulated EGR

The implementation of Exhaust Gas Recirculation (EGR) in gas turbines can become an interesting opportunity to enhance the coupling between natural gas fueled GT power plants and Carbon Capture and Storage (CCS) systems. In fact, as the CO2 content of the incoming flow increases, performance of CCS units improves in terms of efficiency and compactness. As a drawback, the oxygen content available for the combustion reaction decreases, making the combustion process challenging in terms of flame stability and therefore engine operability. This work presents the results of an experimental campaign investigating the behavior of an industrial burner operated with simulated EGR. For the investigation EGR is recreated by diluting standard air with CO2. The burner is operated at ambient pressure in a single sector optical test rig with tubular quartz liner, using natural gas as fuel. The effect of fuel split between premix and pilot line was investigated along with the lack of oxygen caused by EGR. OH* chemiluminescence imaging was employed to study flame topology, and exhaust gas analysis was performed. Emission measurements showed significant NOx reduction, but at the same time as expected CO levels increased remarkably under EGR-like conditions. Additionally, CO2 addition is found to trigger thermoacoustic instabilities in certain conditions, limiting the EGR operability window.

Stability study of flame structure using photodiodes in surface flame burners

Radiation spectroscopy can be effective in identifying pollutants and species. By examining a photodiode, the frequency peaks obtained from the analysis, and the range in which the cell flame is converted to a surface flame, we obtained the value ratio of the cell flame to the surface flame in the range of 0.7–0.74 in different powers. The frequency peak in this range decreases from the maximum value of 9.9823 Hz to its minimum value of 9.058 Hz in different powers. By analyzing the temperature compared to the frequency peak, we found that in the range of equivalence ratio 0.7–0.75, the frequency peak decreases from 9.5 to 9.9 Hz to 8.7–9 Hz. The temperature has an increasing behavior, and in the equivalence ratio, the temperature is in the range of 1400–1500 °C, i.e., at its maximum value. We observed the cell formation process and its conversion to surface flame by flame detection. The flame height in the cellular and superficial regions is in the range of 0.65–0.85, which is the minimum flame height of 3–10 mm, and NO and CO were examined in the ratio of different equations and compared with temperature. In the ratio equivalence ratio of 0.77–0.81 in the temperature range of 1500 °C (maximum), the value of NO is about 16 ppm (maximum), and the value of CO is about 2 ppm (minimum). That is, when the temperature is at its maximum, it becomes CO minimum and NO maximum. This can be used for different applications such as similar and industrial burners.

Ammonia blends for gas-turbines: Preliminary test and CFD-CRN modelling

Ammonia, with its high hydrogen density, cost effectiveness and ease of storage, is emerging as a potential fuel to meet decarbonisation targets in various sectors. However, the combustion of pure ammonia poses challenges due to its low calorific value and reactivity. Existing gas turbine combustion systems, refined over decades with conventional fuels, struggle to maintain comparable flue gas emission concentrations when burning ammonia.Overcoming this challenge requires a paradigm shift in gas turbine combustion, with implications for chemistry and combustor design methodology. Research into the chemical kinetic mechanism for ammonia combustion worldwide reveals differences in flame radical pools compared to methane combustion. The dominant NOx formation mechanism shifts to a "fuel-bound nitrogen" type, which differs from the "thermal" mechanism in hydrocarbon and hydrogen combustion.The integration of chemical reaction rates into Computational Fluid Dynamics (CFD) models with transport equations results in impractical computational times for industrial applications. Therefore, streamlined approaches such as chemical reaction reduction methods are being developed. This involves the construction of lumped parameter models (Chemical Reactor Network - CRN) to identify key parameters that affect species production. A reliable CRN implementation involves the identification of critical volumes using a preliminary CFD approach (CFD-CRN).This paper analyses preliminary experimental tests by Baker Hughes on an industrial burner using different ammonia, hydrogen, and methane fuel mixtures. The NOx results show a different behavior between methane and hydrogen. While the detailed mechanisms behind these results remain open questions, the CFD-CRN modelling approach is adopted. A proposed CRN is investigated for methane, hydrogen, and ammonia blends, providing insight into key parameters and a reasonable physical explanation for the different NOx results. A single calibration parameter (ϕpilot/ϕref) is used to predict accurately NOx emissions using experimental data available from experimental campaign.

Modeling Flame Transfer Functions of an Industrial Premixed Burner

Abstract This paper presents an analysis of the unsteady heat release rate response of industrially relevant axisymmetric premixed flames to harmonic velocity perturbations. The heat release rate response, quantified using the flame transfer function (FTF) definition, is measured from an acoustically forced swirl burner under perfectly premixed conditions. To understand the features of the measured FTF, a physics-based analytical model is developed in this study. To describe the heat release rate dynamics, a model for the flame spatiotemporal response is derived in the linear limit using the G-equation formulation. Inputs to the flame response model are selected to be consistent with values observed in the corresponding industrial burner, based on experimental and numerical studies. The relative contributions of acoustic and convecting vortical disturbances on specific features of the FTF are explored in this study. The results highlight the importance of capturing the appropriate disturbance velocity field as an input to the flame response model for accurate FTF predictions.

SEGMENTATION OF INDUSTRIAL BURNER FLAMES: A COMPARATIVE STUDY FROM TRADITIONAL IMAGE PROCESSING TO MACHINE AND DEEP LEARNING

Abstract. In many industrial processes, such as power generation, chemical production, and waste management, accurately monitoring industrial burner flame characteristics is crucial for safe and efficient operation. A key step involves separating the flames from the background through binary segmentation. Decades of machine vision research have produced a wide range of possible solutions, from traditional image processing to traditional machine learning and modern deep learning methods. In this work, we present a comparative study of multiple segmentation approaches, namely Global Thresholding, Region Growing, Support Vector Machines, Random Forest, Multilayer Perceptron, U-Net, and DeepLabV3+, that are evaluated on a public benchmark dataset of industrial burner flames. We provide helpful insights and guidance for researchers and practitioners aiming to select an appropriate approach for the binary segmentation of industrial burner flames and beyond. For the highest accuracy, deep learning is the leading approach, while for fast and simple solutions, traditional image processing techniques remain a viable option.

Characterisation of turbulent non-premixed hydrogen-blended flames in a scaled industrial low-swirl burner

The performance of a scaled industrial, non-premixed, low-swirl burner design was experimentally investigated for hydrogen addition to natural gas. Two strategies for introducing hydrogen are considered, namely, conserving (i) heat input and (ii) velocity/volumetric flow of the original fuel. This work characterises the effects on key performance metrics of the burner as hydrogen fraction is increased. Compared with natural gas, the results with hydrogen showed a 33 % reduction in the radiant fraction and up to a 380 % increase in NOx emissions. The lift-off height was reduced by a maximum of 23 % and 51 % for addition of 10 and 30 vol% hydrogen addition, respectively, with 100 % cases becoming completely attached to the burner. The influence of hydrogen-addition strategy and air adjustment was shown to be significant with respect to NOx emissions but less significant than the resulting changes in fuel composition and heat input with respect to flame appearance, stability and radiant heat transfer.