High temperature air combustion (HiTAC): How it all started for applications in industrial furnaces and future prospects

Weber, Roman; Gupta, Ashwani K.; Mochida, Susumu

doi:10.1016/j.apenergy.2020.115551

Cited by 68 publications

(30 citation statements)

References 36 publications

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“…This work is an answer to the worth-exploiting issue raised in a recent review in this field . The present experimental and numerical results provide direct evidence that flameless combustion has a significant advantage for the reduction of homogeneous fuel NO x using N-containing gaseous fuels.…”

Section: Discussionmentioning

confidence: 59%

“…Moreover, the homogeneous fuel NO mechanisms under flameless combustion and swirl flame combustion have not been compared. It was also pointed out in a recent review 33 that "there are hardly any applications of flameless oxidation for the reduction of NO x using N-containing fuels and this issue requires further examination". These gaps will be filled in this work.…”

Section: Introductionmentioning

confidence: 99%

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Comparative Study between Flameless Combustion and Swirl Flame Combustion Using Low Preheating Temperature Air for Homogeneous Fuel NO Reduction

Ding

Shi

et al. 2021

Energy Fuels

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The reduction of NO x emission in the combustion process is of vital importance to satisfy the increasingly strict NO x emission standards. Although substantial progress has been made for fuel NO reduction in conventional flame combustion, the homogeneous fuel NO mechanism in flameless combustion has not been systematically investigated. This paper performs a detailed comparative study between flameless combustion and conventional swirl flame combustion for homogeneous fuel NO reduction by both experiments and numerical simulations. The simulations are validated with experiments. It is found that the equivalence ratio (Φ) is significant for the stability and performance of flameless combustion. First, we found that the critical Φ to achieve flameless combustion is reduced with the increase of air preheating temperature. Second, importantly, with the increase of Φ from 0.68 to 0.82 a decreasing tendency of fuel NO emission is found in our experiments, which is the opposite of high temperature combustion. Considering that CO emissions are sharply increased when Φ > 0.8, there is a recommended Φ (i.e., Φ = 0.8 for the present study) to obtain the minimum emissions of fuel NO and CO in flameless combustion. Moreover, our experiments for the first time show that flameless combustion can reduce the homogeneous fuel NO emission by 60–85% relative to swirl flame combustion. Reaction pathway analysis demonstrates that in flameless combustion fuel NO is mostly formed via the NH3 → NH2 → HNO → NO path while NO is reduced through the pathway NO → HCN → NCO → N2. The present study reports the advantage of flameless combustion using low preheating temperature air for significant reduction of homogeneous fuel NO and provides new fundamental understandings of the fuel NO mechanism.

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Section: Discussionmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Comparative Study between Flameless Combustion and Swirl Flame Combustion Using Low Preheating Temperature Air for Homogeneous Fuel NO Reduction

Ding

Shi

et al. 2021

Energy Fuels

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“…There are numerous numerical simulations of batch processes of biomass combustion [31] and gasification [32] where a gasification agent or combustion air is blown (typically from the bottom) through a biomass bed that remains stationary. Biomass gasification with high-temperature air [33] has also being modelled [34], confirming an increased gasification rate and a higher producer-gas yield. In the above cited works, either the Newton-Raphson method (home-made software) was used, or the CFD solver was used.…”

Section: Objectivesmentioning

confidence: 69%

On the Mathematical Modelling of a Moving-Bed Counter-Current Gasifier Fuelled with Wood-Pellets

et al. 2021

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The subject of this work is the mathematical modelling of a counter-current moving-bed gasifier fuelled by wood-pellets. Two versions of the model have been developed: the one-dimensional (1D) version-solving a set of Ordinary Differential Equations along the gasifier height-and the three-dimensional (3D) version where the balanced equations are solved using Computational Fluid Dynamics. Unique procedures have been developed to provide unconditionally stable solutions and remove difficulties occurring by using conventional numerical methods for modelling counter-current reactors.The procedures reduce the uncertainties introduced by other mathematical approaches, and they open up the possibility of straightforward application to more complex software, including commercial CFD packages. Previous models of Hobbs et al., Di Blasi and Mandl et al. used a correction factor to tune calculated temperatures to measured values. In this work, the factor is not required. Using the 1D model, the Mandl et al. 16.6 kW gasifier was scaled to 9.5 MW input; the 89% cold-gas efficiency, observed at 16.6 kW input, decreases only slightly to 84% at the 9.5 MW scale.

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“…2,3,8 For instance, as summarized in a recent review, 56 over the past two decades, per METI some 39,000 HiTAC burners were installed, at least, in 7867 industrial furnaces worldwide, producing massive fuel savings of 1721 billion liters of crude oil/year. Weber et al 56 estimated that 68 billion liters per year of fuel oil savings and 180 billion tons per year of CO 2 reduction will be achieved by 2030 through the use of only HiTAC technology in industrial furnaces. However, there are still some issues concerning MILD combustion to be resolved.…”

Section: Introductionmentioning

confidence: 99%

“…Such technologies can concurrently satisfy both needs of high thermal efficiency and low exhaust emissions (e.g., NO x and CO) for application systems. , During 1990s, the MILD-like technologies were developed independently by Wünning and Wünning , (WS GmbH, Germany) and Nippon Furnace Kogyo Kaisha Ltd. (NFK-Japan) , collaborating with the International Flame Research Foundation (IFRF), , by different acronyms such as FLOX, , HiTAC, − CDC, FLC, which are to be specifically introduced in the next section. Afterward, the MILDC occurrence and characteristics have been highly extensively investigated in the international combustion community, particularly, by Blasiak’s group, , Cavaliere’s group, − Costa’s group, − Dally’s group, − Gupta’s group, − Kumar’s group, − Mi’s group, − Rota’s group, , Swaminathan’s group, − and Weber’s group, ,,− producing nearly 1000 research papers and reports in the literature (obtained by search online).…”

Section: Introductionmentioning

confidence: 99%

Review on MILD Combustion of Gaseous Fuel: Its Definition, Ignition, Evolution, and Emissions

Wang

et al. 2021

Energy Fuels

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Combustion of fossil fuels has been continuously generating over 70% of the total energy for our human society, concurrently emitting vastly greenhouse gases and ecologically harmful pollutants. To mitigate the adverse issue, combustion technologies of a new type were successfully developed and debuted around 1990, associated with various terms of "flameless oxidation (FLOX)", "flameless combustion (FLC)", "high-temperature air combustion (HiTAC)", and "moderate and intense low-oxygen dilution (MILD) combustion". These combustion processes may be regarded as similar or the same class of combustion, because they all involve high preheat and deep dilution of individual reactants (nonpremixed) or the reactant mixture (premixed), prior to main combustion reactions, with high-temperature flue gases (burnt products) internally and/or externally. Very significantly, all of these combustion technologies can simultaneously achieve high efficiency and ultralow emissions of nitric oxides (NOx), light, and noise. This class of combustion has been frequently unified as "MILD combustion". Highly worthy to note, as a particular type of combustion, the MILD combustion has thus far been most extensively explored, resulting in many hundreds to 1000 academic articles published by various energy-related journals and conferences. The present review summarizes the research progress in the gaseous-fuel MILD combustion on its definition, ignition, evolution, and NOx emissions, specifically, through its aspects associated with open jet flames in hot coflow and industrial flames in combustion chamber or furnace. Also, discussions are provided on the relevant terminologies, existing problems, and further fundamental issues.

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High temperature air combustion (HiTAC): How it all started for applications in industrial furnaces and future prospects

Cited by 68 publications

References 36 publications

Comparative Study between Flameless Combustion and Swirl Flame Combustion Using Low Preheating Temperature Air for Homogeneous Fuel NO Reduction

Comparative Study between Flameless Combustion and Swirl Flame Combustion Using Low Preheating Temperature Air for Homogeneous Fuel NO Reduction

On the Mathematical Modelling of a Moving-Bed Counter-Current Gasifier Fuelled with Wood-Pellets

Review on MILD Combustion of Gaseous Fuel: Its Definition, Ignition, Evolution, and Emissions

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