Pyrolysis of low-rank coal with heat-carrying particles in a downer reactor

Fushimi, Chihiro; Okuyama, Shuhei; Kobayashi, Miho; Koyama, Masato; Tanimura, Hayabusa; Fukushima, H.; Thangavel, Sivasakthivel; Matsuoka, Koichi

doi:10.1016/j.fuproc.2017.06.029

Cited by 16 publications

(9 citation statements)

References 40 publications

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“… 38 They are easier to participate in chemical reactions including hydrodeoxygenation, hydrodesulfurization, or hydrodenitrogenation under action of H 2 . 25 Thus, a part of phenols, oxygenated compounds, and heterocyclic compounds converted into aromatics in the effect of H 2 from SCGG and WSG. Also, they may react with steam under SCGG at a relatively high temperature, translating into non-condensable gases, resulting in the decrease of oxygenated compounds in tar.…”

Section: Resultsmentioning

confidence: 99%

“…The residence time of coal particles in the reactor was about 2–3 s according to literatures' method. 25 The generated char particles fell into the char collection section during the pyrolysis process, and the gaseous pyrolysis products outflowed through the product export section and then were further cooled down into tar and water. At the same time, the pyrolysis gases were analyzed by a Raman laser gas analyzer (RLGA-174b) after filtration.…”

Section: Methodsmentioning

confidence: 99%

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Effect of hydrogen-rich gas from char gasification on rapid pyrolysis products of low rank coal in a downer pyrolyzer

Cheng

et al. 2021

RSC Adv.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Effect of hydrogen-rich gas from char gasification on rapid pyrolysis products of low rank coal in a downer pyrolyzer

Cheng

et al. 2021

RSC Adv.

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“…The solid particle materials in their system were silica sand, glass beads, and FCC particles. In this study, silica sand was used as a solid particle material, which was commonly used as a medium particle in the fast pyrolysis downer reactor. , Their downer reactor was referred to as a typical downer reactor in this study. The schematic drawing of their downer reactor is shown in Figure a, as explained in the first paragraph of this section.…”

Section: Simulation and Proceduresmentioning

confidence: 99%

Fast Pyrolysis Downer Reactor: Effect of Reactor Geometry on the Hydrodynamics

Soanuch

Korkerd

Pareek

et al. 2022

Ind. Eng. Chem. Res.

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Downer reactors are the reactors of choice for fast chemical reactions, such as those associated with cracking of heavier feedstock in petroleum refineries. The objective of this study was to investigate the hydrodynamics of the downer reactor for biomass fast pyrolysis with specific emphasis on understanding the effect of the reactor geometry on the system hydrodynamics. Three-dimensional transient Eulerian–Eulerian simulations using the kinetic theory of granular flow were used to evaluate the effect of reactor tapering and cone position on the resulting hydrodynamics. It was found that optimal positioning of the cone could improve the mixing, while the suitable tapered downers could improve radial solid distribution while still resulting in a mean gas residence time within a range suitable for biomass fast pyrolysis.

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“…15−17 Wang et al 18 conducted bituminous coal pyrolysis in a downer reactor and found that the optimal pyrolysis temperature was 933 K and the corresponding tar yield reached 14.5 wt %. Also, Fushimi et al 13 chose the downer as a pyrolyzer and reported that, when the temperature was 1173 K with particle sizes in the range 0.035−0.5 mm, the yield of gaseous products was increased to 21.2%.…”

Section: Introductionmentioning

confidence: 99%

Simulation of Heat Transfer in a Downer-Type Pyrolyzer with Binary Particles by Considering Carrying Gas Role in the Coal Heating Process

Lian,

Zhang,

Pan

et al. 2024

Ind. Eng. Chem. Res.

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Heat transfer between binary particles in an internally heated downer pyrolyzer was carefully studied because it is an important element for the reactor design, but a consensus on the heat transfer process has not been achieved. Compared with the experimental, numerical simulation can provide more details for understanding the heat transfer process. In this work, the widely used multifluid model (MFM) was adopted with considering the multiscale heat convection, conduction, and radiation behaviors inside the downer pyrolyzer. To clearly recognize the exact route of how heat transfers from high-temperature char to low-temperature coal, herein, the rate of each heat transfer way was calculated and counted separately. It is found that the heat radiation and conduction directly transferred from char to coal are all relatively small, and the gas–coal convection is the main factor in the coal heating process. However, the heat carried by the gas into the pyrolyzer only accounts for less than 0.1% of the heat received by the coal, implying that the gas phase is only the heat source by direct contact while the char is the indirect but main heat source. This was confirmed by the thermal balance analysis. Therefore, a conclusion of two-stage heat convection processes was proposed, in which the heat first transfers from char to gas, then from gas to coal, and these two stages belong to heat convection. Hence, the gas phase plays an intermediate medium role in the heat transfer process. Furthermore, the final temperature of the coal increases with the decrease in heat carrier diameter but is not sensitive to the gas velocity. This work is expected to provide guidance for the optimization of an efficient downer-type pyrolyzer.

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Pyrolysis of low-rank coal with heat-carrying particles in a downer reactor

Cited by 16 publications

References 40 publications

Effect of hydrogen-rich gas from char gasification on rapid pyrolysis products of low rank coal in a downer pyrolyzer

Effect of hydrogen-rich gas from char gasification on rapid pyrolysis products of low rank coal in a downer pyrolyzer

Fast Pyrolysis Downer Reactor: Effect of Reactor Geometry on the Hydrodynamics

Simulation of Heat Transfer in a Downer-Type Pyrolyzer with Binary Particles by Considering Carrying Gas Role in the Coal Heating Process

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