Reaction Rate of Microwave Pyrolysis of Coal in Char Bed

Yul, Chang; Kim, Boris I.; Lumpkin, Robert E.; Quinga, E. M. Y.

doi:10.1080/08843759308916129

Cited by 13 publications

(7 citation statements)

References 4 publications

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“…This may be the result of carbon deposit activation leading to formation of new porous structure in the carbon layer. Because char is a good receptor of microwave energy (Cha et al 1993;Menendez et al 1999) during the HTT modification, when the hybrid carbon-silica samples are subjected to action of microwaves, creation of high temperature in the carbon phase is most likely. Such conditions, in the presence of the oxidizing agent such as water makes the activation more effective than during modification in the autoclave.…”

Section: Resultsmentioning

confidence: 99%

“…However, a very interesting and useful source of thermal energy are microwaves. This technology makes it possible to carry out the chemical reactions which couldn't be performed in traditional conditions in so short time or with so high yield (Cha et al 1993;Cha and Kim 2001;Ania et al 2004). Therefore, the aim of this work is to study the influence of hydrothermal modification with steam or liquid water by using the classical autoclave or the microwave reactor on the changes in structural and energetic characteristics of carbon-silica adsorbents (carbosils) by means of nitrogen adsorption, thermogravimetry (TG) and thermodesorption of water under the quasi-isothermal conditions (Q-TG) methods.…”

Section: Introductionmentioning

confidence: 99%

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Structural and energetic properties of carbosils hydrothermally treated in the classical autoclave or the microwave reactor

Skubiszewska–Zięba

2008

Adsorption

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Carbon/silica adsorbents (carbosils) prepared by pyrolysis of CH 2 Cl 2 at 823 K and the reaction time from 0.5 to 6 h on the mesoporous silica gel surface (Si-60, Merck, granule size 0.2-0.5 mm) and then hydrothermally treated at 473 K with steam or liquid water by using the classical autoclave with traditional heating way or in the microwave reactor were studied by means of TG, adsorption and Q-TG methods. Changes in the structural characteristics of hybrid adsorbents before and after hydrothermal treatment were analyzed on the basis of nitrogen adsorption. Thermal properties of initial and modified samples as well as concentration of carbon deposit were studied using thermogravimetry (TG) in the range of 293-1273 K. The adsorbed water layers were investigated by means of thermodesorption of water under the quasi-isothermal conditions (Q-TG) in the range of 293-573 K. Concentration of weakly and strongly adsorbed water and the surface free energy on the interphase of adsorbent/water were calculated. It was stated that hydrothermal treatment in the microwave reactor, contrary to that in the classical autoclave, allows to obtain adsorbents with noticeably higher values of total pore volume in relation to the initial adsorbents and in majority with a higher specific surface area. Application of microwave energy allows to obtain adsorbents with lower values of surface free energy in relation to the initial adsorbents and those modified in the autoclave.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural and energetic properties of carbosils hydrothermally treated in the classical autoclave or the microwave reactor

Skubiszewska–Zięba

2008

Adsorption

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“…These latter admixtures showed temperature runaways with 10% HCFeCr more pronounced between 400°C and 800°C within 5.4 minutes. According to Cha and co-workers, 11) thermal runaway is observed when material temperatures reach a certain temperature and its loss factor is sharply raised. The increase of loss factor leads to increase of power dissipation and also increase the material temperature.…”

Section: Microwave Heating Curvesmentioning

confidence: 99%

“…Other substances included for example different chars. 11,12) Various workers have introduced chromite and manganese ore fines into coke composites in order to enhance the coke strength and density as well as to produce desired intermediate or end metallic products. 13,14) Various investigators have utilized microwave heating to enhance the coke making process, such as a microwave hybrid system described by Wagener et al 15) and Du Broff et al, 16) addition of additives, such as metal oxides, to enhance microwave heating, 16,17) reaction rate investigations of microwave pyrolysis of coal in a char bed, 11) a method for the manufacture of metallurgical blast furnace coke from a mixture of heavy coking coal and non-or weakly coking coal by means of rapid microwave heating rate (25 kW, 30°C/minute), 18) and more recently coke making from a high volatile bituminous coal within 10 minutes.…”

Section: )mentioning

confidence: 99%

“…2,9,11) This necessitates the addition of a microwave susceptor material, such as coke or char or metal oxides to enhance the heating of the coal. The addition of a proportion of the susceptor enhances both the heating rate in a microwave field, due to a very rapid energy transfer into the material being heated, and also the rate of reduction of the susceptor for the case where the susceptor is a metal oxide.…”

Section: )mentioning

confidence: 99%

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Influence of Additives on Cokemaking from a Semi-soft Coking Coal during Microwave Heating

Coetzer¹,

Rossouw

2012

ISIJ Int.

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Coke was produced from a Waterberg semi-soft coking coal using microwave heating and selected microwave susceptors. Waterberg semi-soft coking coal is poorly susceptible to microwave heating, especially below 500°C, and therefore requires microwave susceptors. Susceptors were selected from ferroalloy fines and their respective ores.Various batch experiments were performed on compressed discs utilizing a resonant microwave cavity at a constant 915 MHz frequency to heat a batch of about 5 to 7 kg of the semi-soft coking coal (sscc) to obtain coke. Materials were characterized using Inductive Coupled Plasma (ICP) analysis and coke strength tests.Dielectric property results showed that chrome and manganese ores, as well as their respective high carbon ferrochrome and ferromanganese alloys, are suitable microwave susceptors to enable rapid coke formation during microwave heating. Coke formation was completed within 2 to 3 hours up to 1 100°C compared to 21 hours for a commercial plant since microwave heating reduces the "cold centre" in a coke oven. Obtained coke strengths were slightly lower than for a commercial coke but still of a high quality. It was also shown that the admixture of chrome ore resulted in its partial reduction which will be advantageous to the ferrochrome industry since this method allows for recycling of fines without additional pelletisation. The results also showed that microwave energy has the potential to be employed during commercial coke formation, either on its own or as a hybrid technology.

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