Studies of NO−Char Reaction Kinetics Obtained from Drop-Tube Furnace and Thermogravimetric Experiments

Sun, Shaozeng; Zhang, Juwei; Hu, Xidong; Wu, Shaohua; Yang, Jiancheng; Wang, Yang; Qin, Yukun

doi:10.1021/ef800695k

Cited by 30 publications

(17 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…32,34 The CaO surface area increases with the burnout level because of an increase in the CaO content per gram of char as the carbonaceous mass burns away. These results indicate that the CaO surface area is a more reliable basis than the BET surface area for correlating the burnout level with surface area measurements, which agrees with Sun et al 45 Effect of the Method B Burnout Level on the NO− Char Rate Constant. Figures 4 and 5 show the variations of NO−char reaction rates with the char burnout level obtained under method B conditions for biomass, graphite, and six coal chars.…”

Section: ■ Results and Discussionsupporting

confidence: 89%

Kinetics of NO Reduction by Coal, Biomass, and Graphitic Chars: Effects of Burnout Level and Conditions

et al. 2014

View full text Add to dashboard Cite

During the combustion of coal and other carbonaceous materials, the heterogeneous reaction of NO with the evolving char created in the combustion process is important for understanding the formation and reduction of NO. This investigation quantifies the effects of char burnout level and conditions on the kinetics of NO reduction by chars made from coals ranging in rank from lignite to low-volatile bituminous (Beulah Zap, Dietz, Utah Blind Canyon, Pittsburgh #8, and Pocahontas #3) as well as graphite and coconut char. Kinetic data were measured in a packed-bed reactor at temperatures between 723 and 1173 K. The rate constant for the NO−char reaction was found to depend upon the extent of burnout/conversion and conditions under which the char was burned out. The NO−char rate constant consistently decreases with increasing burnout when the char burnout levels are accomplished in a drop tube reactor at 1800 K and 3−5% O 2 . However, the NO−char rate constant increases as char burnout increases (up to 90%) when the char burnout levels result from reacting the char with 3050 ppm of NO in a packed bed at 723−1173 K. For the latter case, the relationship of the NO−char rate constant (on the basis of moisture ash-free char mass) and char burnout is approximately linear with roughly the same upward slope between 20 and 80% burnout for all coal chars studied. The activation energy of the NO−char reaction is apparently independent of both char burnout level and burnout conditions. The CO 2 /CO ratio in the exhaust stream appears to correlate with the NO−char rate constant for the chars burned out at low-temperature conditions.

show abstract

Section: ■ Results and Discussionsupporting

confidence: 89%

Kinetics of NO Reduction by Coal, Biomass, and Graphitic Chars: Effects of Burnout Level and Conditions

et al. 2014

View full text Add to dashboard Cite

show abstract

“…However, there are a number of studies indicating that the heterogeneous reduction of NO using biomass char is also noteworthy (Dong et al, 2007(Dong et al, , 2009aGarijo et al, 2003;Lin et al, 2010;Sun et al, 2009;Yin et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…Most previous researches on the reaction between coal char and NO are conducted at a temperature below 1173 K, which is widely recognized as the transition temperature from dynamic-control region to diffusion-control region (Aarna and Suuberg, 1997;Sun et al, 2009). However, there is no widely recognized transition temperature for the reaction between biomass char and NO.…”

Section: Introductionmentioning

confidence: 99%

Kinetics investigation on the reduction of NO using straw char based on physicochemical characterization

Wang

Tan

et al. 2011

Bioresource Technology

View full text Add to dashboard Cite

“…According to a previous study, 41 the char-NO reaction is found to be first-order with respect to NO. The calculation method of intrinsic reactivity of char-NO reaction R 4 can be found elsewhere 42 using the classical Thiele analysis. The Arrhenius plot of R 4 is obtained by linear fitting as shown in Figure 5.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Effect of Stoichiometric Ratio on Char-Nitrogen Conversion under High-Temperature Entrained Flow Combustion Conditions

Sun

Wang

et al. 2018

Energy Fuels

View full text Add to dashboard Cite

The char-O2 reaction under high-temperature entrained flow conditions was investigated experimentally and numerically to study the effect of the stoichiometric ratio (SR) on char-nitrogen conversion. A numerical model was established based on the unsteady convection-diffusion and reaction equations, in which Stefan flow was considered. The change of specific surface area during char combustion was considered by locally using the Random Pore Model (RPM). The intrinsic reactivity parameters of char-O2 and char-NO reactions were measured using a thermal gravimetric analyzer (TGA) and drop tube furnace (DTF), respectively. The numerical results indicated that the predictions of carbon conversion and NO release agreed well with experimental data. Based on numerical results, for a given carbon conversion, with the decrease of SR, the kinetics-diffusion controlled char-O2 reaction is pushed toward the kinetics-controlled regime, leading to more significant local carbon conversion and thus more developed pore structure inside char particles, including higher porosity and larger specific surface area. Therefore, the oxidation of char-nitrogen occurs more deeply inside char particles and NO release prefers to diffuse toward the particle center, rather than outward. The larger specific surface area deep inside the char particle also gives rise to the total char-NO reaction rate at a lower SR. As a result, the total fractional conversion of char-N to NO decreases as SR decreases under high-temperature entrained flow combustion conditions.

show abstract

Studies of NO−Char Reaction Kinetics Obtained from Drop-Tube Furnace and Thermogravimetric Experiments

Cited by 30 publications

References 29 publications

Kinetics of NO Reduction by Coal, Biomass, and Graphitic Chars: Effects of Burnout Level and Conditions

Kinetics of NO Reduction by Coal, Biomass, and Graphitic Chars: Effects of Burnout Level and Conditions

Kinetics investigation on the reduction of NO using straw char based on physicochemical characterization

Effect of Stoichiometric Ratio on Char-Nitrogen Conversion under High-Temperature Entrained Flow Combustion Conditions

Contact Info

Product

Resources

About