Study on the scaling-up of spouted fluidized beds based on the dual-nozzle spouting unit

doi:10.11949/0438-1157.20250468

Abstract

Abstract:

The spouted fluidized bed has been widely applied in the fields such as the preparation of energy storage particles due to its ability to achieve stable particle circulation at the scale of the reactor. However, the circulation of particles is affected by operating conditions, container size and other conditions, which makes it difficult to scale up the bed. The idea of this paper is to abandon the concept of vertical independent spouting, and instead the use of the coordinated spouting dual nozzles as the basic unit to scale-up the bed. The research shows that in two-dimensional and three-dimensional rectangular spouted bed, the coordinated deflected spouting of dual nozzles has a higher gas-solid mixing efficiency and a wider operating range. After 20 seconds of gas-solid mixing in the two-dimensional spouted bed, the temperature drop of the dual nozzle compared with the single nozzle increased by 12%, and the variance of particle temperature decreased, demonstrating stronger uniformity. When the dual nozzle bed is longitudinally expanded to four nozzles, a slugging fluidized state is very likely to occur. By moderately reducing the gas velocity to 1.75—2.00 m/s, the four-nozzle spouted bed can achieve independent vertical jet movement of multiple nozzles and has an excellent gas-solid mixing effect. This study deeply reveals the important value of the coordinated spouting unit of dual nozzles in the scaling-up of the spouted bed, and opens up a new path for the scaling-up design of rectangular spouted beds.

Key words: spouted bed, scale-up, CFD-DEM, deflected spouting, multiphase flow

摘要：

喷动床凭借其能在反应器尺度上实现颗粒稳定循环的特点，被广泛应用在储能颗粒制备等领域。然而，颗粒的循环运动会受到操作条件、容器尺寸等条件的影响，导致床层放大困难。研究思路在于摒弃垂直独立喷动的理念，将双喷口协同作用作为基本单元并开展喷动床放大设计。研究表明，在二维和三维矩形喷动床中，双喷口协同偏转喷动具备更高的气固混合效率与更宽的操作区间。二维喷动床内气固混合20 s后，双喷口比单喷口的温度下降同比提升了12%，且颗粒温度方差降低，展现出更强的均匀性。当双喷口流化床纵向扩展为四喷口时，极易出现腾涌状态。通过适度降低气体速度至1.75~2.0 m/s，四喷口喷动床可以实现多喷口独立垂直喷动，并具有优良的气固混合效果。本研究深入揭示了双喷口协同喷动单元在喷动床放大过程中的重要价值，为矩形喷动床的放大设计开辟了新路径。

关键词: 喷动床, 放大, CFD-DEM, 倾斜喷动, 多相流

CLC Number:

TK 02

Yuanhe YUE, Weiwei ZHAO, Linjie HOU, Yong ZHANG, Zhonghao RAO. Study on the scaling-up of spouted fluidized beds based on the dual-nozzle spouting unit[J]. CIESC Journal, 2025, 76(11): 5664-5676.

岳远贺, 赵微微, 侯林杰, 张勇, 饶中浩. 基于双喷口喷动单元的喷动床放大研究[J]. 化工学报, 2025, 76(11): 5664-5676.

Figures/Tables 16

Fig.1 Schematic diagram of the bottom spouts for each situation case

Table 1 The main simulation parameters

参数	数值
固相
颗粒直径	2.5 mm
颗粒密度	2526 kg/m³
固相温度	363.15 K
恢复系数(p-p)	0.97
恢复系数(p-w)	0.97
颗粒床层高度	0.12 m
气相
气体密度	1.2 kg/m³
气体动力黏度	1.8 Pa·s
流体温度	293.15 K
压力	101325 Pa

Fig.2 Comparison of the average vertical velocity of particles and experimental data when the height level is 0.25 m

Fig.3 The comparison of the average particle temperature between the simulation results and the experimental data

Fig.4 Snapshots of void distribution of different Usp under different distance conditions

Fig.5 Snapshots of void distribution of different Ubg under different distance conditions,

Fig.6 Time-evolution profiles of mean particle temperature and variance under single spouting and two-joint spouting

Fig.7 Snapshots of the movement of temperature-colored particles in a two-dimensional spouted bed

Fig.8 Snapshots of void distribution under different thickness ratios of the spout to the spouted bed

Fig.9 The variation of the average particle temperature with the thickness ratio and the background velocity

Fig.10 Time-evolution profiles of mean particle temperature and variance under different background velocities

Fig.11 Snapshots of void distribution of each spout under three-dimensional multi-spout conditions

Fig.12 The particle movement flow state of each spout under three-dimensional multi-spout conditions

Fig.13 The evolution curves of particle temperature and variance over time of three-dimensional multiple spouts

Fig.14 The evolution curves of the mixing index of three-dimensional multiple spouts over time

Fig.15 Snapshots of the movement of temperature-colored particles in a three-dimensional spouted bed

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