Effect of an Acoustic Field on the Combustion of Coal Particles in a Flat Flame Burner

Yavuzkurt, Savas; Ha, Man Yeong; Reethof, G.; Koopmann, Gary H.; Scaroni, Alan W.

doi:10.1115/1.2905913

Cited by 16 publications

(21 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the whole, the results revealed that the acoustic effects were more pronounced for the initial period of particle heat-up. The above two works 55,57) also include brief overviews of earlier publications on the acoustically improved fuel combustion.…”

Section: Improvement In Fuel Combustion Efficiencymentioning

confidence: 99%

“…Yavuzkurt et al 55) investigated the effect of an acoustic field on the combustion of coal particles in a flame burner by injecting the particles of 20-70 mm into the burning gas stream and by monitoring the light intensity emitted from the flame. Averaged values of light intensity were 2.5-3.5 times higher at SPL of 145-150 dB and frequency of 2 000 Hz compared to those without sound application.…”

Section: Improvement In Fuel Combustion Efficiencymentioning

confidence: 99%

See 1 more Smart Citation

High Power Ultrasonics in Pyrometallurgy: Current Status and Recent Development

2005

View full text Add to dashboard Cite

In recent years, a large number of studies have been published on the use of high intensity ultrasonics in various high temperature technologies. This paper provides an overview of the recent achievements and ongoing works on the application of high intensity sound waves to pyrometallurgy and its related areas. The published results have strongly suggested that ultrasonics has the potential to play a more significant role in such areas as the dedusting of high-temperature exhaust gas, improvement of fuel-combustion efficiency, control of air-pollutant emissions, improvement of the quality of ingots, production of metal powders and ascast composite materials.At higher temperatures, special attractiveness of sound waves is associated with the fact that the waves can propagate through gas, liquids, and solids, and thus supply the acoustic energy from a cooled sonic generator to materials being processed under high temperature conditions. This provides a unique tool, for example, for controlling the rates of interfacial phenomena that is unachievable by any other methods under high temperatures.Industrial competitiveness of the ultrasonic-based technologies is reinforced by the relatively low cost of power-generating equipment and ultrasonic transducers. However, further research efforts are called for to develop new heat-resistant waveguide materials and to integrate the ultrasonic installations with existing industrial facilities in high temperature technologies.KEY WORDS: pyrometallurgy; high temperature; sonoprocessing; high power ultrasonics; non-linear phenomena; air pollutants; continuous casting; melt atomization; cast composites.applications have been summarized in a book by one of the authors of the present review. 4)The following two circumstances make ultrasonics especially applicable to high-temperature technologies: 1) There is a severely limited choice of techniques available for supplying energy under conditions involving higher temperatures. Among these techniques, sonic/ ultrasonic treatment or sonoprocessing should be competitive as regards both technique and cost, because it provides an effective transmission of acoustic energy from the ultrasonic generators to the materials being processed at a relatively low cost for ultrasonic equipment. 2) It is well-known that interfacial phenomena play an important role in governing many high-temperature processes. Examples are mass and heat transfer, crystal growth during the solidification of liquid metals, wetting, and emulsification. Sonic and ultrasonic waves propagate through homogeneous elastic mediums without significant losses. However, when the waves are incident upon an interface, the scattering or reflecting or of the waves from the interface is responsible for a number of nonlinear phenomena that occur at the interfaces. These provide a unique tool for controlling the rates of interfacial phenomena. Such a tool is unachievable by any other methods. Along with improvements in the earlier methods of sonoprocessing, a number of new ultrasonic appl...

show abstract

Section: Improvement In Fuel Combustion Efficiencymentioning

confidence: 99%

Section: Improvement In Fuel Combustion Efficiencymentioning

confidence: 99%

High Power Ultrasonics in Pyrometallurgy: Current Status and Recent Development

2005

View full text Add to dashboard Cite

show abstract

“…Remarkably, air‐driven dynamical weakening is seen for granular beds of large inertia particles such as sand suggesting that the hydrodynamic gas‐solid interaction is greatly promoted by oscillations. In accordance with this argument, chemical engineering studies have long reported that fluidization‐based processes can be promoted by oscillations [ Kwauk , ; Yavuzkurt et al , ; Valverde et al , ; Lepek et al , ] even with no net fluid flow [ Deng and Kwauk , ; Kwauk , ]. For example, the settling of large inertia glass beads ( d p =440μm) in a water‐glycerol mixture and of resin particles ( d p =290–440μm) in water under gravity is slowed down by vertical oscillations of the liquid and eventually stopped [ Deng and Kwauk , ].…”

Section: Fluidization Enhancement Under Oscillatory Viscous Flowsmentioning

confidence: 93%

Dynamical weakening by fluidization under oscillatory viscous flows

Valverde

2015

JGR Solid Earth

View full text Add to dashboard Cite

Dynamical weakening of granular materials plays a critical role on diverse geological events such as seismic faulting and landslides. A common feature in the dynamics of these processes is the development of fluid‐solid relative flows, which could lead to fluidization by hydrodynamic viscous stresses. This work is focused on analyzing hydrodynamic fluidization under oscillatory viscous flows as a possible driving mechanism for dynamical weakening. The theoretical estimations and experimental observations presented and reviewed suggest that fluidization can be greatly promoted by oscillatory viscous flows, which are usually expected in geological events involving vibration of granular materials in viscous fluids. Fluidization under oscillatory viscous flows may occur at not excessively large vibration velocities of fine particles in gases or relatively larger particles in liquids or supercritical fluids. In particular, the enhancement of fluidization by high‐frequency vibrations would be a powerful mechanism to promote dynamical weakening of fine powders in dry fault gouges, failure of liquid‐ (or supercritical fluid‐) saturated beds, and sustained fluidization of pyroclastic flows and lahars.

show abstract

“…In trying to circumvent this deficieny, it has been contended that acoustic energy is capable of promoting the agglomeration of fine ash particles entrained in high temperature gas streams. [2][3][4][5][6][7][8] Acoustic agglomeration is a process in which high intensity sound is used to assemble micron and submicron sized particles in aerosols. The effect of sound is to cause relative motions between particles and increase their collision rate.…”

Section: Introductionmentioning

confidence: 99%

“…Acoustic energy can also be employed to increase the rate and extent of coal combustion, allowing combustors to release larger amounts of heat. [7][8] Thermo-acoustic systems can therefore perform several beneficial functions such as: promoting higher combustion efficiency, fuel savings, reduced pollutant formation, increased fuel residence time in the combustion chamber, increased convective heat transfer rates and lower operating and equipment costs. The basic mechanisms that trigger the beneficial consequences are invariably associated with controlling the acoustic field, in order to improve mixing and/or heat transfer.…”

Section: Introductionmentioning

confidence: 99%

A novel investigation of the thermoacoustic field inside a Rijke tube

Entezam

Moorhem

Majdalani

1998

7th AIAA/ASME Joint Thermophysics and Heat Transfer Conference

View full text Add to dashboard Cite

In this paper, results proceeding from experimental studies and computational simulations of the time-dependent flowfield inside a Rijke tube are presented and interpreted. A theoretical discussion based on existing speculations and scaling analyses is carried out. The main results include a similarity parameter that appears to play an important role in the heat driven oscillations. This parameter relates heat perturbations to velocity, pressure, and the square of a characteristic length. A simple theory that attributes heat oscillations to the combined effects of pressure and velocity oscillations is discussed via computational, experimental, and scaling considerations. Since previous analytical theories link heat oscillations to either velocity or pressure oscillations, the current analytical model agrees with and reconciles between existing speculations. In compliance with the Rayleigh criterion, it is found that the heat source must be positioned at a critical distance of l/4 from the Rijke-tube lower end for resonance to occur. This observation confirms our proposed interpretation since the critical point where coupling is maximized corresponds to a spatial location where the acoustic intensity, product of both acoustic velocities and pressures, is largest. Numerical simulations show that pressure oscillations inside the Rijke tube grow exponentially with increasing heat input. With a sufficiently small heat input, the acoustic sinks exceed the sources and acoustic damping takes place. When the heat input is augmented beyond a critical threshold, acoustic sinks become insufficient causing rapid acoustic amplification by virtue of internal energy accumulation.

show abstract

Effect of an Acoustic Field on the Combustion of Coal Particles in a Flat Flame Burner

Cited by 16 publications

References 0 publications

High Power Ultrasonics in Pyrometallurgy: Current Status and Recent Development

High Power Ultrasonics in Pyrometallurgy: Current Status and Recent Development

Dynamical weakening by fluidization under oscillatory viscous flows

A novel investigation of the thermoacoustic field inside a Rijke tube

Contact Info

Product

Resources

About