Experimental Investigation on the Impact of Tube Bundle Designs on Heat Transfer Coefficient in Gas-Solid Fluidized Bed Reactor for Fischer-Tropsch Synthesis

Abstract

The impact of vertical heat exchanging tube bundle on heat transfer coefficient (HTC) has been investigated locally and instantaneously using a sophisticate heat transfer technique using glass beads solid particles of 210 μm average size and 2500 kg/m3 solid density (Geldart B particles), with a static bed height of 0.35 m as bed material. A mimicked Fischer-Tropsch fluidized bed with vertical heat exchanging tubes is designed and built in this study. Heat transfer performance is also investigated by using two different tubes arrangement (square-pitch and triangular-pitch tubes arrangement). To represent the heat exchanging tubes used in the Fischer-Tropsch process, stainless-steel heat exchanging tubes inserted vertically, each with a diameter of 0.012 m, were used in each tubes arrangement occupying 25% of the column cross-section area. The experiments were performed in a 0.13 m inner diameter Plexiglas fluidized bed reactor with varied gas flowrates (0.2-0.48) m/s at numerous radial positions along the diameter of the column (±0.58, ±0.33, and ± 0.03) and two axial locations (H/D = 1.153 and 1.923). It was found that HTCs significantly enhance with increasing the gas flowrates for all radial positions for square-pitch tubes arrangement. While different behavior can be noticed in the radial positions with triangular-pitch tube arrangement, especially near the wall region (±0.33). Also, the local heat transfer coefficient (LHTC) improved with increasing the axial positions by 12.06% at highest gas flowrates (0.48 m/s). Moreover, the square-pitch tubes arrangement showed a significant increase and uniformity in HTC when measured instantaneously comparing with other tubes arrangement. Furthermore, the findings of this study will improve awareness of vertical tubes' effect on heat transfer in a fluidized bed reactor. Moreover, the data acquired from this investigation can be employed to validate reactor models, CFD codes, and simulations in order to support the design and scale-up processes of such reactors.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Advanced Heat Transfer Technique; Fischer-Tropsch Synthesis; Gas-Solid Fluidized Bed; Local Heat Transfer Coefficient; Tubes Arrangement; Vertical Heat Exchanging Tubes

International Standard Serial Number (ISSN)

0735-1933

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2022 Elsevier, All rights reserved.

Publication Date

01 Jul 2022

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