Wall-to-Bed Heat Transfer at Minimum Gas-Solid Fluidization

Zhang, Huili; Degrève, Jan; Baeyens, Jan; Dewil, Raf

doi:10.1155/2014/163469

Cited by 6 publications

(7 citation statements)

References 18 publications

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“…According to Goossens [48], the particle suspension film thickness and its film conductivity and suspension residence time within the film are interrelated. The suspension film thickness is generally an order of magnitude or larger than the particle size used in the experiments, as demonstrated at minimum fluidization conditions [49].…”

Section: The Relationship Between Particle Velocity and Heat Trans-mentioning

confidence: 89%

Wall-to-Suspension Heat Transfer in a CFB Downcomer

Zhang

Degrève

Dewil

et al. 2015

Journal of Powder Technology

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With the development of circulating fluidized beds (CFB) and dense upflow bubbling fluidized beds (UBFB) as chemical reactors, or in the capture and storage of solar or waste heat, the associated downcomer has been proposed as an additional heat transfer system. Whereas fundamental and applied research towards hydrodynamics has been carried out, few results have been reported on heat transfer in downcomers, even though it is an important element in their design and application. The wall-to-suspension heat transfer coefficient (HTC) was measured in the downcomer. The HTC increases linearly with the solids flux, till values of about 150 kg/m2 s. The increasing HTC with increasing solid circulation rate is reflected through a faster surface renewal by the downflow of the particle-gas suspension at the wall. The model predictions and experimental data are in very fair agreement, and the model expression can predict the influence of the dominant parameters of heat transfer geometry, solids circulation flow, and particle characteristics.

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Section: The Relationship Between Particle Velocity and Heat Trans-mentioning

confidence: 89%

Wall-to-Suspension Heat Transfer in a CFB Downcomer

Zhang

Degrève

Dewil

et al. 2015

Journal of Powder Technology

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“…97 There are two common approaches for predicting heat transfer in a bubbling fluidized bed, (a) the packet renewal model, and (b) the two-fluid model (TFM). 97,98 For the packet renewal model, Mickley and Fairbanks postulated that the heat transfer occurs by packets of emulsion phase that are periodically replaced from the heat- transfer surface by bubbles. 59,97 The packet renewal model is not appropriate when heat penetration to the packet is low and packet residence time is short.…”

Section: General Heat Transfer In Fluidizedmentioning

confidence: 99%

“…To address this limitation, a time-independent contact resistance was introduced in a study by Baskakov et al 99 It was later adapted in a study by Baeyens and Geldart. 98,100 An input for the packet renewal model is the thermal conductivity of the emulsion phase, estimated by measuring temperature at different locations of the bed. The measurement is difficult to undertake when the thermal gradient in the bulk of the bed is low, relatively small heat fluxes are used, or when large temperature fluctuations are present in the bed.…”

Section: General Heat Transfer In Fluidizedmentioning

confidence: 99%

Electrically Heated Fluidized Beds─A Review

Ahmed,

Duchesne,

Tan

et al. 2024

Ind. Eng. Chem. Res.

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Fluidized beds heated via fossil fuel combustion have been widely used in industry for various applications. Heating these fluidized beds with clean electricity is emerging as a promising solution to reduce greenhouse gas emissions, improve overall energy efficiency, and for some applications, improve product quality. This review covers the development status of electrically heated fluidized beds (EHFBs) with a variety of heating principles, including Joule heating, induction heating, electromagnetic irradiation, sonication, plasma heating and gas preheating. An analysis of the advantages and disadvantages of these heating principles is presented, along with their suitability for different applications. Current and potential industrial applications using EHFBs for highly diversified processes, from material processing and biomass gasification to space exploration, are highlighted. Each application presents its own unique opportunities and challenges. The selection of a method to deliver electrical heat depends on the specific purpose of each application, materials involved, and the required configuration of the EHFB. Hence, methods to assess key performance indicators are described. To date, only a few applications have been commercialized, mostly for drying and material processing. Recommendations for EHFB advancement are provided so that their full potential can be realized.

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“…-Percentage of H 2 , CO 2 is increased and CO decreased gradually with the rise in moisture percentage of feedstock -The amount of CO 2 improves gradually, and CO decreases slightly, C n H m and CH 4 remained smoothly as with the increase of steam to fuel ratio [54] Normal angle type Gasification agent in this kind of distributor enter normal to the rector bed; some important type is perforated distributer, sparger and metal distributer. A perforated distributor plate is a circular plate [45], in which holes are made to supply the gasifying agent in the gasifier reactor as shown in Figure 6 (a).…”

Section: Different Design and Process Parameters Observationsmentioning

confidence: 99%

“…Figure 6. (a): Perforated distributer plate (modified from[45]), (b): Nozzle type distributer plate (modified from[46]). …”

mentioning

confidence: 99%

Advancements and challenges in the fluidized bed gasification system: A comprehensive review

ANTIL

Sachdeva

Sharma

2023

Journal of Thermal Engineering

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A gasifier employs partial ignition of biomass and conversion to gaseous fuels of high calorific value. Bubbling fluidized bed gasifier is a promising one amongst other gasification technologies like fixed bed, entrained flow etc. It has several noteworthy advantages like large- and small-scale applications, efficient heat and mass transfer rates due its fuel flexibility, low capital and operating costs, etc. However, low mixing rate of biomass feedstock and gasifying agent, high tar content in the product gas and low calorific value of producer gas are some of its limitations which need sincere attention to enhance its performance. The present study analyzes the effect of design variables of the proposed gasifier reactor for different feedstock along with the operating variables on the quality of producer gas. This review paper examines the present global status of biofuels, different types of gasification technologies, approaches adopted for the gasification, different parameters affecting gasification performance, enhancement of product gas conditioning, technical and cost-effective viability and the future prospects of gasification.

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Wall-to-Bed Heat Transfer at Minimum Gas-Solid Fluidization

Cited by 6 publications

References 18 publications

Wall-to-Suspension Heat Transfer in a CFB Downcomer

Wall-to-Suspension Heat Transfer in a CFB Downcomer

Electrically Heated Fluidized Beds─A Review

Advancements and challenges in the fluidized bed gasification system: A comprehensive review

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