On the (MILD) combustion of gaseous, liquid, and solid fuels in high temperature preheated air

Weber, Roman; Smart, J. P.; Kamp, Willem vd

doi:10.1016/j.proci.2004.08.101

Cited by 307 publications

(226 citation statements)

References 10 publications

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“…This results in a more distributed heat release region and a lower peak temperature, which are precisely desired in the MILD combustion technology for the reduction of NOx formation [57,58]. Figure 19 compares the gas phase temperature PDF obtained from experiment and simulation respectively.…”

Section: Flame Structurementioning

confidence: 99%

Transported PDF Modeling of Ethanol Spray in Hot-Diluted Coflow Flame

Naud

Roekaerts

2015

Flow Turbulence Combust

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This paper presents a numerical modeling study of one ethanol spray flame from the Delft Spray-in-Hot-Coflow (DSHC) database, which has been used to study Moderate or Intense Low-oxygen Dilution (MILD) combustion of liquid fuels (Correia Rodrigues et al. Combust. Flame 162, 759-773, 2015). A "Lagrangian-Lagrangian" approach is adopted where both the joint velocity-scalar Probability Density Function (PDF) for the continuous phase and the joint PDF of droplet properties are modeled and solved. The evolution of the gas phase composition is described by a Flamelet Generated Manifold (FGM) and the interaction by exchange with the mean (IEM) micro-mixing model. Effects of finite conductivity on droplet heating and evaporation are accounted for. The inlet boundary conditions starting in the dilute spray region are obtained from the available experimental data together with the results of a calculation of the spray including the dense region using ANSYS Fluent 15. A method is developed to determine a good estimation for the initial droplet temperature. The inclusion of the "1/3" rule for droplet evaporation and dispersion models is shown to be very important. The current modeling approach is capable of accurately predicting main properties, including mean velocity, droplet mean diameter and number density. The gas temperature is under-predicted in the region where the enthalpy loss due to droplet evaporation is important. The flame structure analysis reveals the existence of two heat release regions, respectively having the characteristics of a premixed and a diffusion flame. The experimental and modeled temperature PDFs are compared, highlighting the capabilities and limitations of the proposed model.

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Section: Flame Structurementioning

confidence: 99%

Transported PDF Modeling of Ethanol Spray in Hot-Diluted Coflow Flame

Naud

Roekaerts

2015

Flow Turbulence Combust

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“…In many publications it is reported that flameless combustion is achieving a more uniform temperature distribution compared to conventional combustion and that this higher temperature uniformity results in higher efficiencies 17,18 .…”

Section: Temperature Uniformitymentioning

confidence: 99%

Parametric optimization study of a multi-burner flameless combustion furnace

Danon

Cho

Jong

et al. 2011

Applied Thermal Engineering

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A parametric study on a 300 kWth furnace equipped with three pairs of regenerative flameless combustion burners has been performed. Each burner pair has a rated thermal power of 100 kWth firing Dutch natural gas. The objective of the study was to optimize the furnace performance, i.e., to maximize the cooling tube efficiency and minimize the CO and NO emissions. In the study the following parameters were varied: the positions of the burners in the furnace (burner configuration), the firing mode (parallel and staggered), the excess air ratio (λ) and the cycle time (tcycle). Also, the influence on the furnace performance of the jet momentum of the combustion air and the temperature uniformity in the furnace were studied. It was concluded that staggered firing mode is disadvantageous, since it results in significantly higher NO emissions than parallel firing mode. Also, out of the five investigated burner configurations one has been exempted, since its cooling tube efficiency was significantly lower compared to the other configurations. Furthermore, a horizontal setup of the firing burners improves the cooling tube efficiency at a fixed temperature uniformity. Also, for the burner configurations with the firing burners positioned closer to the regenerating burners and further from the stack, the temperatures in the regenerators are higher, leading to higher combustion air preheat temperatures. The temperature in the regenerators was also influenced by the cycle time; higher cycle times leading to higher (peak) temperatures in the regenerators. Finally, this temperature in the regenerators was shown to be more decisive for the final amount of CO emitted than the excess air ratio or the jet momentum. In all experiments, due to differences in path length of the mean flow, higher CO emissions were measured in the flue gas from the regenerators compared to in the flue gas from the stack. These two trends in the CO emissions were not observed for the NO emissions. Dear Prof. David Reay, once again we would like to sincerely thank you and the reviewers for their (positive) comments on our paper. In the short list below we summarize the minor changes we have made to our manuscript ATE-2011-215R1 based on the latest reviewers' suggestions.We have made the following changes to our manuscript: 1) on page 3, we added before the description of the fuel composition 'has a net (lower) calorific value of 31.669 MJ/m3 and' 2) on page 5, we added in the definition of the cooling tube efficiency 'based on the net (lower) calorific value of the fuel.' 3) on page 7, we added the word 'as'.We hope that our manuscript, in this form, can be accepted for publication with Applied Thermal Engineering.Hoping on a positive decision, with our best regards, Teo Cho and Bart DanonResponse to Reviewers M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPTHIGHLIGHTS accompanying ATE-2011-215R2 > Burner positioning effects in a multi-burner flameless combustion furnace. > Horizontal burner setup improves efficiency at constant tempera...

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“…Above all peak temperatures are not present, which allow to stabilize the flame, but at the same time, they cause the formation of nitric oxides. The International flame Research Foundation have been carried out experiments on an 880 kW furnace using solid, gaseous and liquid fuels [4][5]. Suda et al [6] investigated experimentally the NOx emissions, char burnout, flame stability and ignition delay in a 250 kW furnace.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of MILD (moderate or intense low-oxygen dilution) combustion of coal in a furnace with different coal gun positions

Perrone¹,

Amelio²

2016

IJHT

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The aim of this study is to analyze the temperature field, the specie concentrations of MILD coal combustion in a pilot furnace through the CFD. The attention is focused especially on the effect of the position of coal guns and their distance from the central air jet, in order to investigate both temperature and specie concentration distributions. The authors have performed several simulations in three dimensional steady-state condition of a quarter of the IFRF furnace using a high bituminous A coal. The Eddy Dissipation Model has been used to describe and model the interaction between turbulence and chemistry, while the P1 model has been used for the radiation. In order to describe the solid phase and the combustion process, the Lagrangian description has been used and sub-models have been implemented for devolatilization and char burnout. In particular has been used the Chemical Percolation Model (CPD) for the devolatilization and the intrinsic model for the oxidation of char. The turbulence phenomenon has been modeled resorting to the standard k-ε model, considering the standard wall functions for the wall treatment. The results show that the mild condition is obtained for all three configurations. When the distance between the coal guns and the center air jet are furthest, the oxygen concentration is lowest, consequently the combustion takes place in a fuel-rich zone. This condition can influence the NOx emissions.

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On the (MILD) combustion of gaseous, liquid, and solid fuels in high temperature preheated air

Cited by 307 publications

References 10 publications

Transported PDF Modeling of Ethanol Spray in Hot-Diluted Coflow Flame

Transported PDF Modeling of Ethanol Spray in Hot-Diluted Coflow Flame

Parametric optimization study of a multi-burner flameless combustion furnace

Numerical simulation of MILD (moderate or intense low-oxygen dilution) combustion of coal in a furnace with different coal gun positions

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