Effect of Coke Breeze Distribution on Coke Combustion Rate of the Quasi-particle

Ogi, Hiroshi; Maeda, Takayuki; Ohno, Ko Ichiro; Kunitomo, Kazuya

doi:10.2355/isijinternational.isijint-2015-089

Cited by 13 publications

(7 citation statements)

References 7 publications

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“…The ceramic fiber was used as heat insulator. The Pt basket was hung on a thermobalance 17) by Pt wire. The inner diameter of this reaction tube is 35 mm.…”

Section: Methodsmentioning

confidence: 99%

Effect of H2 Concentration on Carbon Deposition Reaction by CO–H2 Gas Mixture at 773 K to 973 K

et al. 2019

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CO-H 2 gas mixture is often used for gas-based DRI process where carbon deposition reaction and Fe 3 C metal dusting play negative roles for a stable reduction operation. Fe 3 C decomposition leads to the formation of iron particles which is a catalyst for carbon fiber deposition. Because of the parallel occurrence of these reactions, kinetic analysis of them would be complicated. In the present study, to simplify the kinetic analysis, quantitative analysis of carbon fiber deposition was conducted by using thermobalance. A powdery iron sample was prepared by reduction of Fe 2 O 3 with 100vol%H 2 at 673 K. Carbon deposition on the iron sample was investigated under flowing 100%CO, 90vol%CO-10vol%H 2 , 75vol%CO-25vol%H 2 , 50vol%CO-50vol%H 2 , 25vol%CO-75vol%H 2 and 10vol%CO-90vol%H 2 gas mixtures at 773 K, 873 K and 973 K. Results showed that amount of the deposited carbon in the CO-H 2 gas mixture are larger than that in the pure CO gas. The largest amount of deposited carbon was obtained in 75vol%CO-25vol%H 2 gas mixture at 873 K. According to SEM observations and weight change measurements, carbon was deposited in fiber shape on the iron surface and amount of it was increased linearly with an increase in sample's weight change. The rate constant of carbon fiber deposition was calculated considering Rideal mechanism with focusing on elementary reaction steps. It was found that the rate constant of the hydrogen-oxygen reaction step was the largest indicating a significant effect of hydrogen on promoting carbon deposition 773 K and 873 K. This would be due to the removing oxygen from CO by hydrogen on the iron catalyst. KEY WORDS: metal dusting; reduced iron; CO-H 2 gas mixture; carbon deposition reaction; carbon fiber deposition.

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“…The ceramic fiber was used as heat insulator. The Pt basket was hung on a thermobalance 17) by Pt wire. The inner diameter of this reaction tube is 35 mm.…”

Section: Methodsmentioning

confidence: 99%

Effect of H2 Concentration on Carbon Deposition Reaction by CO–H2 Gas Mixture at 773 K to 973 K

et al. 2019

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“…It can be seen from Table 6 that the activation energy of the MBF calculated by DRPM is slightly lower than that of QPF. In order to better reflect the height of barriers, Equation (18) was introduced to calculate the apparent activation energy of samples,…”

Section: Combustion Kinetic Parametersmentioning

confidence: 99%

“…In recent years, Processes 2020, 8, 475 2 of 16 researchers have begun to use a quasi-particle structure to describe the existence of fuel inside the sintering mixture [16,17]. In order to exclude the interference brought by other reactions, Al 2 O 3 pure powder reagent is often used in many studies on quasi-particles sinter to replace other materials used in production for experimental exploration [18].…”

Section: Introductionmentioning

confidence: 99%

Combustion Kinetics Characteristics of Solid Fuel in the Sintering Process

et al. 2020

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In order to systematically elucidate the combustion performance of fuel during sintering, this paper explores the influence of three factors, namely coal substitution for coke, quasi-particle structure and the coupling effect with reduction and oxidation of iron oxide, on fuel combustion characteristics, and carries out the kinetic calculation of monomer blended fuel (MBF) and quasi-granular fuel (QPF). The results show that replacing coke powder with anthracite can accelerate the whole combustion process. MBF and QPF are more consistent with the combustion law of the double-parallel random pore model. Although the quasi-particle structure increases the apparent activation energy of fuel combustion, it can also produce a heat storage effect on fuel particles, improve their combustion performance, and reduce the adverse effect of diffusion on the reaction process. In the early stage of reaction, the coupling between combustion of volatiles and reduction of iron oxide is obvious. The oxidation of iron oxide will occur again when the combustion reaction of fuel is weakened.

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“…2. The SiO 2 basket was hung in a thermobalance 15) by Pt wire. The initial weight of the carbon fiber sample was fixed as 0.15 g.…”

Section: Carbon Fiber Sample Preparation and Experimentalmentioning

confidence: 99%

Effect of Temperature and CO2 Concentration on Gasification Behavior of Carbon Fiber Containing Fine Iron Particles

et al. 2019

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In direct reduced iron (DRI) process, CO-H 2 gas mixture is used as a reducing agent, which may make the operation unstable owing to a carbon deposition reaction and metal dusting reaction through Fe 3 C. The Fe 3 C decomposition reaction forms iron particles which acts as a catalyst for a carbon fiber deposition reaction at around 600°C. Such a carbon fiber deposition not only causes the loss of the carbon but also decrease the reducibility of the gas. On the other hand, the carbon fiber is likely gasified by CO-CO 2 gas mixture at around 1 000°C. In the present study, the carbon fiber gasification was quantitative analyzed using thermobalance to clarify the mechanism of the carbon fiber gasification reaction. To prepare a carbon fiber sample, the carbon was deposited with a reduced iron catalyst at 600°C in 50vol%CO-50vol%H 2. Carbon fiber containing fine iron particles was gasified with various compositions of CO-CO 2 gas mixture at 1 000°C. Further, the effect of temperature of the gasified reaction was also investigated at 800°C, 900°C and 1 000°C in 100vol%CO 2. According to XRD analysis of the sample after gasification, Fe 3 C in the sample before gasification decomposed to iron and a portion of iron was oxidized to Fe 3 O 4 and FeO when gasification ratio was high. The transition of carbon fiber shape was confirmed by SEM observation. Fine iron particles located on the tip of carbon fiber were sintered during gasification of carbon fiber. The mechanism of carbon fiber gasification was evaluated considering crystalline size, such as L a and L c that show (002) and (110) determined by XRD analysis, respectively. It was found that the L a decreased with gasification ratio at all temperatures. In addition, L c decreased after gasification at 1 000°C. KEY WORDS: carbon metal dusting; Fe 3 C; gasification; CO-CO 2 gas mixture; carbon fiber deposition.

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Effect of Coke Breeze Distribution on Coke Combustion Rate of the Quasi-particle

Cited by 13 publications

References 7 publications

Effect of H<sub>2</sub> Concentration on Carbon Deposition Reaction by CO–H<sub>2</sub> Gas Mixture at 773 K to 973 K

Effect of H<sub>2</sub> Concentration on Carbon Deposition Reaction by CO–H<sub>2</sub> Gas Mixture at 773 K to 973 K

Combustion Kinetics Characteristics of Solid Fuel in the Sintering Process

Effect of Temperature and CO<sub>2</sub> Concentration on Gasification Behavior of Carbon Fiber Containing Fine Iron Particles

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