Three-dimensional combined pyrometric sizing and velocimetry of combusting coal particles II: Pyrometry

Tóth, Pál; Draper, Teri; Palotás, Árpád Bence; Ring, Terry A.; Eddings, Eric G.

doi:10.1364/ao.54.004916

Cited by 7 publications

(4 citation statements)

References 41 publications

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“…It is worth noting that the present work focuses on a zero-dimensional configuration without considering the complex turbulent flows of realistic situations; some conclusions may not be totally applicable to a realistic situation where coal particles interact with flows. , The present study will be extended to comprehensively explore the coal devolatilization characteristics in more realistic situations in future work.…”

Section: Discussionmentioning

confidence: 99%

Numerical Studies of Coal Devolatilization Characteristics with Gas Temperature Fluctuation

et al. 2018

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In the present work, coal devolatilization characteristics in a hot gaseous environment with gas temperature fluctuation are investigated numerically with the chemical percolation devolatilization (CPD) model and the two-step (TS) model in a zero-dimensional configuration. The numerical results are first validated against the experimental data, showing that the CPD model can reproduce the coal devolatilization process well. The effects of mean gas temperature, gas temperature fluctuation amplitude, and coal particle size on coal devolatilization are then explored. The particle temperature is found to fluctuate with the gas temperature fluctuation at the same frequency. However, the particle temperature shows a delay in responding to the gas temperature fluctuation, with smaller particles having a shorter delay time. It is also found that the gas temperature fluctuation facilitates coal devolatilization. In particular, higher mean gas temperature and fluctuation amplitude values reduce the start time of the devolatilization and result in higher total volatile and tar yields. Smaller particles are more sensitive to gas temperature fluctuation and are easier and faster to devolatilize, producing more volatiles and tar. Compared to the CPD model, the devolatilization process predicted by the TS model generally starts earlier and the final volatile yield is overestimated. Moreover, the TS model predictions have a shorter delay time and larger fluctuation amplitude of coal particle temperature compared to the CPD model predictions, which indicates that the TS model is more apt to be affected by gas temperature fluctuation than the CPD model.

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Section: Discussionmentioning

confidence: 99%

Numerical Studies of Coal Devolatilization Characteristics with Gas Temperature Fluctuation

et al. 2018

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“…In this way, each image recorded by the camera included the radiation intensity distribution of the coal jet flame in two selected wavelength ranges at the same time and then could be used to calculate the temperature distribution. This two-color method using a single camera for temperature measurement can easily and accurately obtain the instantaneous temperature distribution and avoid problems including synchronization and mismatches in spectral response between the image sensors in multicamera systems. − …”

Section: Experimental Approachmentioning

confidence: 99%

“…This two-color method using a single camera for temperature measurement can easily and accurately obtain the instantaneous temperature distribution and avoid problems including synchronization and mismatches in spectral response between the image sensors in multicamera systems. 39 − 41 …”

Section: Experimental Approachmentioning

confidence: 99%

Effect of Jet Velocity on the Formation of Moderate or Intense Low-Oxygen Dilution Combustion of Pulverized Coal

Huang

et al. 2023

ACS Omega

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Moderate or intense low-oxygen dilution (MILD) combustion of pulverized coal is regarded as a new combustion technology with great potential due to its advantages of reducing NO x emission and improving the uniformity of heat flux in the furnace. Increasing the jet velocity has been proved to be an important technical means to achieve MILD oxy-coal combustion, especially without a high level of preheat, but the transition mechanism of coal combustion modes with the increase of jet velocity is not clear enough. In this work, a high-velocity coal-laden jet combustion system on the basis of a flat-flame burner was designed to study the effect of jet velocity on the formation of MILD combustion of pulverized coal. The combustion mode transition of the pulverized coal jet is revealed by analyzing the flame structure, temperature, radiation, and reaction intensity through a variety of optical measurement methods. Theoretical criteria for combustion mode were applied to predict the formation of MILD combustion and were validated by the experimental data. In the environment with an ambient temperature of 1600 °C, the transition velocity of the coal jet into the MILD combustion regime is about 50 m/s and about 100 m/s at 5 and 15% O2 molar fraction, respectively. The dilution effect, jet entrainment, and turbulent mixing in the high-velocity jet, as the key factors to achieve an MILD combustion regime, were analyzed theoretically and experimentally. The dilution effect inherent in the jet significantly reduces the reactant concentration and ultimately reduces the reaction intensity and flame brightness while the entrainment of the jet promotes the radial dispersion of particles and the flame uniformity, which is dominant at lower jet velocities. Strong turbulent mixing promotes the ignition and volatile combustion, which is dominant at higher jet velocities.

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“…This is a well-established method for measuring flame temperature and soot concentration in laboratory flames, , diesel engines, as well as coal and gas combustion . The technique can also be used to measure the temperature of particles. − However, 2C-PYR can only be applied to processes with a luminous flame, i.e. in the presence of soot, since it assesses temperature from the soot emission.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames

Ögren

Sepman

et al. 2017

Energy Fuels

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Optical and intrusive measurement techniques for temperature and soot concentration in hot reacting flows were tested on a small-scale burner in fuel-rich, oxygen-enriched atmospheric flat flames produced to simulate the environment inside an entrained flow reactor. The optical techniques comprised two-color pyrometry (2C-PYR), laser extinction (LE), and tunable diode laser absorption spectroscopy (TDLAS), and the intrusive methods included fine-wire thermocouple thermometry (TC) and electrical low pressure impactor (ELPI) particle analysis. Vertical profiles of temperature and soot concentration were recorded in flames with different equivalence and O2/N2 ratios. The 2C-PYR and LE data were derived assuming mature soot. Gas temperatures up to 2200 K and soot concentrations up to 3 ppmv were measured. Close to the burner surface, the temperatures obtained with the pyrometer were up to 300 K higher than those measured by TDLAS. Further away from the burner, the difference was within 100 K. The TC-derived temperatures were within 100 K from the TDLAS results for most of the flames. At high signal-to-noise ratio and in flame regions with mature soot, the temperatures measured by 2C-PYR and TDLAS were similar. The soot concentrations determined with 2C-PYR were close to those obtained with LE but lower than the ELPI results. It is concluded that the three optical techniques have good potential for process control applications in combustion and gasification processes. 2C-PYR offers simpler installation and 2D imaging, whereas TDLAS and LE provide better accuracy and dynamic range without calibration procedures.

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Three-dimensional combined pyrometric sizing and velocimetry of combusting coal particles II: Pyrometry

Cited by 7 publications

References 41 publications

Numerical Studies of Coal Devolatilization Characteristics with Gas Temperature Fluctuation

Numerical Studies of Coal Devolatilization Characteristics with Gas Temperature Fluctuation

Effect of Jet Velocity on the Formation of Moderate or Intense Low-Oxygen Dilution Combustion of Pulverized Coal

Comparison of Measurement Techniques for Temperature and Soot Concentration in Premixed, Small-Scale Burner Flames

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