Downer reactor simulation and its application on coal pyrolysis: A review

Pan, Xueer; Lian, Wenhao; Yang, Jingxuan; Wang, Junli; Zhang, Zhonglin; Hao, Xiaogang; Abudula, Abuliti; Guan, Guoqing

doi:10.1016/j.crcon.2021.12.003

Cited by 14 publications

(7 citation statements)

References 122 publications

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“…The crucial characteristic steps of the fast pyrolysis process are: the pyrolysis reaction takes place with high heat and heat transfer rates, thus, the particle sizes of biomass materials need to be small enough to enhance such heat transfer; the pyrolysis reaction temperature ranges from 450 to 550°C in the vapor phase; short residence times for the vapor up to two seconds; rapid quenching and condensing the vapors into bio-oil. Common reactor types used for fast pyrolysis are described below [41][42][43][44][45].…”

Section: Fast Pyrolysismentioning

confidence: 99%

“…Bubbles are made at the openings at which the fluidizing gas enters the bed, where the packing solids above the gas entrance are pushed aside until they create a void space through which the gas can enter at the initial fluidization velocity. Uniform mixing, uniform temperature distribution, and operation in a continuous state are the main advantages of bubbling fluidized-bed reactors [43,44].…”

Section: Bubbling Fluidized-bed Reactormentioning

confidence: 99%

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Advances in Bioenergy Production Using Fast Pyrolysis and Hydrothermal Processing

Chandraratne¹,

Daful²

2022

Biomass, Biorefineries and Bioeconomy

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This chapter provides an overview of current efforts and advances as well as environmental and economic aspects of fast pyrolysis and hydrothermal processing, which are potential technologies for bioenergy production, mainly bio-oil and syngas. Biomass is presently the primary bioenergy resource in the world. The chapter presents a brief discussion of sources and compositions of biomass. Biomass is converted to various products using thermochemical conversions. Pyrolysis is a thermochemical process that converts biomass into carbon-rich solid residue, condensable vapors, and non-condensable gases in the absence of oxygen. It is a promising technology for converting biomass into renewable biofuels with environmental and economic advantages. Pyrolysis processes are classified based on their operating conditions and desired products. Two thermochemical processes, fast pyrolysis and hydrothermal processing are reviewed. Fast pyrolysis produces a higher quantity and quality of bio-oil and syngas than slow and intermediate pyrolysis processes. Hydrothermal processing converts wet biomass into carbonaceous biofuel. The ability to produce higher-value bioenergy by these pyrolysis technologies depends on the feedstock and operating condition of the pyrolysis processes. This chapter will present the most promising features of fast pyrolysis and hydrothermal processing along with their optimal pyrolysis conditions in maximizing the production of biofuels.

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Section: Fast Pyrolysismentioning

confidence: 99%

Section: Bubbling Fluidized-bed Reactormentioning

confidence: 99%

Advances in Bioenergy Production Using Fast Pyrolysis and Hydrothermal Processing

Chandraratne¹,

Daful²

2022

Biomass, Biorefineries and Bioeconomy

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“…After that, the downer developed rapidly. At present, under the double carbon policy, the downer will occupy an important position in the chemical and energy sectors 5–7 …”

Section: Introductionmentioning

confidence: 99%

Experimental study on gas–solid flow and heat transfer characteristics in downer moving bed

Zhang

Zhou

et al. 2023

Asia-Pacific J Chem Eng

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As a special flow state of the downer, the downer moving bed has been applied in many fields. With the rapid development of the downer moving bed, experimental studies on the flow and heat transfer characteristics in the bed are urgently needed to promote the further development of it. Therefore, a complete set of downer moving bed experimental equipment is completed in this paper. Key parameters of flow characteristics such as void fraction and particle flow velocity are indirectly calculated through direct measurement of pressure and other data. The experimental results show that the factors affecting the solid circulation flow rate include bed inventory and inlet air velocity. Due to the high packing density of the particles, the void fraction of the downer moving bed has a small relative change. The particle flow velocity increases significantly with the increase of the inlet air velocity. Under the joint effect of particle velocity and void fraction, the variation of heat transfer coefficient along the height of the bed presents a single peak curve. And the heat transfer performance of the downer moving bed is obviously better than that of the downer fluidized bed at the same solid circulating flow rate. The differences between different tube bank arrangements and the single tube are compared. It is concluded that in practical applications, the requirements for heat transfer and heat transfer coefficient should be considered together and the best tube bank arrangement should be selected.

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“…Connecting these kinetics to particle‐scale models is essential to construct computational fluid dynamic (CFD) simulations, which can be used to assess and optimize reactor performance. Computational fluid dynamic simulation of pyrolysis and fast‐pyrolysis has been conducted in a variety of fixed‐bed and fluidized‐bed reactors but the pyrolysis kinetics involved were limited to lignocellulosic biomass and coal‐based feedstocks 52–60 . Studies of the pyrolysis of hydrochars from the organic fraction of MSW, waste biomass, and MSW digestates have been reported but they do not strictly represent hydrochars produced from the mixed MSW typically found in landfills from low‐ and middle‐income regions 29,33,61,62 .…”

Section: Introductionmentioning

confidence: 99%

“…Computational fluid dynamic simulation of pyrolysis and fast-pyrolysis has been conducted in a variety of fixed-bed and fluidized-bed reactors but the pyrolysis kinetics involved were limited to lignocellulosic biomass and coal-based feedstocks. [52][53][54][55][56][57][58][59][60] Studies of the pyrolysis of hydrochars from the organic fraction of MSW, waste biomass, and MSW digestates have been reported but they do not strictly represent hydrochars produced from the mixed MSW typically found in landfills from low-and middle-income regions. 29,33,61,62 Since landfill MSW composition from similar socio-economic regions are often uniform in their composition, 1 pyrolysis kinetics of hydrochars produced from this feedstock has the potential to be relevant to a broad region.…”

mentioning

confidence: 99%

Pyrolysis kinetics of hydrochar using distributed activation energy model

Kamal

Hossain

Salma

et al. 2022

Biofuels Bioprod Bioref

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Producing hydrochar from landfill municipal solid wastes (MSW) is a sustainable alternative to existing waste management practices in low-and middle-income countries. In this study, mixed MSW feedstock (sent for landfilling) was subjected to hydrothermal carbonization to produce hydrochars. The hydrochar showing the highest heating value was subjected to pyrolysis at 5, 10, and 20 K min −1 heating rates. Based on the pyrolysis characteristics, a three pseudo-component-based distributed activation energy model was employed to describe the pyrolysis kinetics. The activation energy distributions for the three pseudo-components were 140 ± 8.7 kJ mol −1 , 190 ± 1 kJ mol −1 and 175.9 ± 24.9 kJ mol −1 , which were able to predict the pyrolysis profile at all heating rates with R 2 > 0.999. Differential thermogravimetric profiles of the hydrochar revealed its pyrolytic reactivity to resemble lignocellulosic constituents. Fouriertransform infrared analysis of the hydrochar showed retention of oxygen-containing functional groups (associated with lignocellulosic constituents) from the parent feedstock.

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Downer reactor simulation and its application on coal pyrolysis: A review

Cited by 14 publications

References 122 publications

Advances in Bioenergy Production Using Fast Pyrolysis and Hydrothermal Processing

Advances in Bioenergy Production Using Fast Pyrolysis and Hydrothermal Processing

Experimental study on gas–solid flow and heat transfer characteristics in downer moving bed

Pyrolysis kinetics of hydrochar using distributed activation energy model

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