Pressure drop and gas holdup in an upward-flow fixed-bed reactor

doi:10.1016/j.cjche.2025.07.010

中国化学工程学报 ›› 2025, Vol. 88 ›› Issue (12): 42-52.DOI: 10.1016/j.cjche.2025.07.010

Pressure drop and gas holdup in an upward-flow fixed-bed reactor

Zhibo Song¹, Jinghao Bi², Xiao Xu², Qiang Yang²

1. Sinopec Engineering Incorporation, Beijing 100101, China;
2. School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China

收稿日期:2025-06-13 修回日期:2025-07-28 接受日期:2025-07-30 出版日期:2026-02-09 发布日期:2025-08-13
通讯作者: Xiao Xu,E-mail:xxu@ecust.edu.cn
基金资助:
This work is financially supported by the National Natural Science Foundation of China (52025103).

Pressure drop and gas holdup in an upward-flow fixed-bed reactor

Zhibo Song¹, Jinghao Bi², Xiao Xu², Qiang Yang²

1. Sinopec Engineering Incorporation, Beijing 100101, China;
2. School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, China

Received:2025-06-13 Revised:2025-07-28 Accepted:2025-07-30 Online:2026-02-09 Published:2025-08-13
Contact: Xiao Xu,E-mail:xxu@ecust.edu.cn
Supported by:
This work is financially supported by the National Natural Science Foundation of China (52025103).

摘要/Abstract

摘要： This study presents a systematic investigation of pressure drop and gas holdup in an upward-flow fixed-bed reactor, examining the effects of bubble size, bed height, particle shape, superficial gas velocity (SGV), and superficial liquid velocity (SLV) based on experimental measurements and empirical correlations. Two bubble generators, namely ring tube generator (RTG) and porous sintered film generator (PSG), are used. Key findings reveal that for the PSG, increasing SGV decreases small-bubble population while promoting large-bubble formation, with the bubbles stabilizing at a Sauter mean diameter (d₃₂) of ~3 mm. The RTG produces stable large bubbles (d₃₂ = 6-7 mm) with minimal size variations across the range of tested SGVs. The pressure drop decreases with an increase in SGV but increases with higher SLV and bed height, primarily due to the reduced liquid holdup and the dominance of static pressure. Smaller bubbles reduce the pressure drop by slowing rise velocity and minimizing frictional resistance. Clover-shaped particles exhibit the highest pressure drop owing to large porosity, while 3-mm toothed spheres show higher pressure drop than 5-mm spheres at high SGV because of intensified capillary forces. The gas holdup increases with increasing SGV and bed height but decreases slightly with increasing SLV. Smaller bubbles enhance gas holdup by improving bed distribution and residence time. The 3-mm toothed spheres show the highest gas holdup due to stronger capillary trapping, whereas the clover-shaped particles exhibit the lowest. Empirical correlations for pressure drop and gas holdup are developed, yielding calculation errors within ±1% and ±20% of the experimental values, respectively.

关键词: Fixed-bed reactor, Pressure drop, Gas holdup, Bubble characteristics

Abstract: This study presents a systematic investigation of pressure drop and gas holdup in an upward-flow fixed-bed reactor, examining the effects of bubble size, bed height, particle shape, superficial gas velocity (SGV), and superficial liquid velocity (SLV) based on experimental measurements and empirical correlations. Two bubble generators, namely ring tube generator (RTG) and porous sintered film generator (PSG), are used. Key findings reveal that for the PSG, increasing SGV decreases small-bubble population while promoting large-bubble formation, with the bubbles stabilizing at a Sauter mean diameter (d₃₂) of ~3 mm. The RTG produces stable large bubbles (d₃₂ = 6-7 mm) with minimal size variations across the range of tested SGVs. The pressure drop decreases with an increase in SGV but increases with higher SLV and bed height, primarily due to the reduced liquid holdup and the dominance of static pressure. Smaller bubbles reduce the pressure drop by slowing rise velocity and minimizing frictional resistance. Clover-shaped particles exhibit the highest pressure drop owing to large porosity, while 3-mm toothed spheres show higher pressure drop than 5-mm spheres at high SGV because of intensified capillary forces. The gas holdup increases with increasing SGV and bed height but decreases slightly with increasing SLV. Smaller bubbles enhance gas holdup by improving bed distribution and residence time. The 3-mm toothed spheres show the highest gas holdup due to stronger capillary trapping, whereas the clover-shaped particles exhibit the lowest. Empirical correlations for pressure drop and gas holdup are developed, yielding calculation errors within ±1% and ±20% of the experimental values, respectively.

Key words: Fixed-bed reactor, Pressure drop, Gas holdup, Bubble characteristics

Zhibo Song, Jinghao Bi, Xiao Xu, Qiang Yang. Pressure drop and gas holdup in an upward-flow fixed-bed reactor[J]. 中国化学工程学报, 2025, 88(12): 42-52.

Zhibo Song, Jinghao Bi, Xiao Xu, Qiang Yang. Pressure drop and gas holdup in an upward-flow fixed-bed reactor[J]. Chinese Journal of Chemical Engineering, 2025, 88(12): 42-52.

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Pressure drop and gas holdup in an upward-flow fixed-bed reactor

Pressure drop and gas holdup in an upward-flow fixed-bed reactor

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