Combustion rates of pulverized coal particles in high-temperature/high-oxygen concentration atmosphere

Saito, Masahiro; Sadakata, Masayoshi; Sato, Masayuki; Soutome, T.; Murata, Hiroyasu; Ohno, Yotaro

doi:10.1016/0010-2180(91)90022-4

Cited by 24 publications

(5 citation statements)

References 8 publications

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“…Heating the coal particles rapidly to high temperatures enhances the chance of simultaneous bond breaking, leading to the release of volatiles within a very short period of time. This rapid formation of volatiles would cause the pressure to build up rapidly within a particle, leading to the explosive release of volatiles even in the form of volatile jets. , As discussed above, the widening of the pores would tend to make the transportation, particularly the diffusion from micropores to macropores, of volatiles easier, leading to the reduced intraparticle secondary reactions. The shortened residence time resulting from the explosive ejection of volatiles would greatly help to reduce both recombination/charring and further thermal cracking reactions of the tar precursors.…”

Section: Resultsmentioning

confidence: 99%

Effects of Heating Rate and Ion-Exchangeable Cations on the Pyrolysis Yields from a Victorian Brown Coal

1999

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A Victorian low-rank coal (Loy Yang) was acid-washed and ion-exchanged with Na and Ca to prepare the H-form, Na-form, and Ca-form coal samples. Two more H-form samples were also prepared by rewashing the Na-form and Ca-form samples with acid. These coal samples were pyrolyzed in a wire-mesh reactor where the secondary reactions of the evolved volatiles were minimized. The ion-exchanged coal samples were found to give very different tar yields from those of the raw coal samples. While the tar yields from the pyrolysis of the raw and H-form coal samples were observed to be very sensitive to changes in heating rate, the tar yields from the Ca-form and Na-form samples showed little heating rate sensitivity. Unlike higher rank coals studied previously, the tar yields from the pyrolysis of the raw coal and the H-form coal samples at 600 °C were found to increase much more than the corresponding increases in the total volatile yields as the heating rate was increased from 1 to 2000 K s -1 . Reexchanging Na in the Na-form sample and Ca in the Ca-form sample with H confirmed the effects of Na and Ca but also suggested that the irreversible structural changes taking place during ion-exchange, possibly including the loss of humic materials and the physical reconfiguration of the macromolecular network, should also be considered to ascertain the effects of ion-exchangeable cations during pyrolysis. The heating rate sensitivity of pyrolysis yields is believed to be at least partly related to the presence of carboxyl/carboxylate groups and other bulky substitution groups in the coal as well as the rapid pressure buildup within the particles. The major roles of ion-exchangeable cations during pyrolysis are also discussed in the paper.

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Section: Resultsmentioning

confidence: 99%

Effects of Heating Rate and Ion-Exchangeable Cations on the Pyrolysis Yields from a Victorian Brown Coal

1999

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“…The laboratory experimental set-up of the HDTF was normally used in the study of coal combustion behaviour. [13][14][15] The core of the experimental set-up mainly consists of 6 facilities: an electrically heated tube furnace, a syringe pump particle feeder, a particle injection probe, a sampling probe, a gas pre-heater and a sample collector. The injection probe and sampling probe are made of high temperature resistance stainless steel.…”

Section: Experiments With the Htdfmentioning

confidence: 99%

Thermal Decomposition Behaviour of Fine Iron Ore Particles

et al. 2014

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In the smelting cyclone of HIsarna process, both thermal decomposition and gaseous reduction of iron ore contribute to the expected pre-reduction degree about 20%. However, the fine ore reduction and melting process in the smelting cyclone is extremely fast and it is very difficult to differentiate between the thermal decomposition and gaseous reduction. This study focused on the thermal decomposition mechanism of the fine iron ore under different conditions. Firstly, the theoretical evaluation has been conducted based on the thermodynamics, and then the laboratory investigation was conducted in three stages with three reactors: the TGA-DSC, the electrically heated horizontal tube furnace and the High-temperature Drop Tube Furnace (HDTF). According to the experimental results of the first two stages and the theoretical evaluation, it was found that the temperature of intensive thermal decomposition of Fe2O3 in the inert gas environment is in the range of 1 473-1 573 K, while the thermal decomposition of Fe3O4 could be sped up when the temperature is above 1 773 K in the inert gas. Temperature plays an important role in the thermal decomposition degree and reaction rate. Finally, it was found that the thermal decomposition of the individual iron ore particles took place very rapidly in the HDTF and no significant influence of the particle size and residence time (t ≤ 2 020 ms) on the equivalent reduction degree could be observed, when the particle diameter was smaller than 250 μm in the CO2 gas.

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“…Other researchers have studied the reactivity of coal chars in entrained flow reactors under rich oxygen conditions and high temperatures in order to obtain kinetic parameters [13,14,15]. These studies have shown that the char combustion rate increases with oxygen concentration and that char gasification with CO 2 may be important under these experimental conditions.…”

mentioning

confidence: 99%

Effect of biomass blending on coal ignition and burnout during oxy-fuel combustion

Arias

Pevida

Rubiera

et al. 2008

Fuel

154

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Oxy-fuel combustion is a GHG abatement technology in which coal is burned using a mixture of oxygen and recycled flue gas, to obtain a rich stream of CO 2 ready for sequestration. An entrained flow reactor was used in this work to study the ignition and burnout of coals and blends with biomass under oxy-fuel conditions. Mixtures of CO 2 /O 2 of different concentrations were used and compared with air as reference. A worsening of the ignition temperature was detected in CO 2 /O 2 mixtures when the oxygen concentration was the same as that of the air. However, at an oxygen concentration of 30% or higher, an improvement in ignition was observed. The blending of biomass clearly improves the ignition properties of coal in air. The burnout of coals and blends with a mixture of 79%CO 2 -21%O 2 is lower than in air, but an improvement is achieved when the oxygen concentration is 30 or 35%. The results of this work indicate that coal burnout can be improved by blending biomass in CO 2 /O 2 mixtures.

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Combustion rates of pulverized coal particles in high-temperature/high-oxygen concentration atmosphere

Cited by 24 publications

References 8 publications

Effects of Heating Rate and Ion-Exchangeable Cations on the Pyrolysis Yields from a Victorian Brown Coal

Effects of Heating Rate and Ion-Exchangeable Cations on the Pyrolysis Yields from a Victorian Brown Coal

Thermal Decomposition Behaviour of Fine Iron Ore Particles

Effect of biomass blending on coal ignition and burnout during oxy-fuel combustion

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