Wu Xiaochen 1a，Zhu Jiabin2，Yang Juan2，Zhong Wenzhen1b，Zhao Kexin1a， Li Hao1b，Duan Guanbin1a
1a. School of Materials Science and Engineering，1b. School of Mechanical Engineering，University of Jinan，Jinan 250022，China；
2. Shandong Fangyi Environmental Protection Technology Co.，Ltd.，Jinan 250022，China
Abstract
Objective The uniformity of airflow and particle distribution inside small vertical bag filters has a significant impact on their dust removal performance and the service life of the filter bags. In traditional structural designs， uneven airflow distribution often leads to excessive particle accumulation on the front filter bags， thereby reducing overall collection efficiency. This study aims to thoroughly investigate the gas-solid two-phase flow characteristics within small vertical bag filters， systematically analyze issues related to the flow field and particle distribution uniformity， and propose structural optimization measures to enhance the overall performance of the dust removal system.
Methods A three-dimensional computational fluid dynamics （CFD） model of the vertical bag filter was developed to simulate and analyze its internal gas-solid flow. The simulations modeled the two-phase flow using the standard k-ε turbulence model and tracked particle motion using the discrete phase model （DPM）. To assess the impact of geometry on flow uniformity， three distinct structural configurations were designed and compared： the baseline conventional design， an optimized design with a gradually diverging inlet duct， and an improved design incorporating a diverging inlet with a perforated flow distribution baffle. The filter bags were arranged in a 9×9 array within the housing. Simulation boundary conditions， including inlet velocity， outlet pressure， and particle diameter and density， were defined based on typical operational parameters. Transient calculations were performed using a pressure-based solver. Pressure-velocity coupling was handled with the SIMPLE algorithm， and second-order upwind discretization schemes were applied to discretize the momentum and turbulence equations to enhance numerical accuracy.
Results and Discussion The simulation results clearly demonstrated significant non-uniformity of particle distribution in the conventional filter design. The first column of filter bags bore most of the dust load， capturing 68.79% of all particles， while the last （ninth） column captured only 2.61%. This extreme disparity highlighted severe overloading of front-line bags and underutilization of downstream bags. Structural modifications improved this distribution. With a gradually diverging inlet， the particle proportion captured by the first column was reduced to 48.11%. When combined with a perforated flow-distribution baffle， it was further decreased to 20.67%， indicating a more even redistribution of dust load towards the rear filter columns. These changes led to directly enhanced system performance. The overall filtration efficiency increased from 69.60% （conventional design） to 75.79% （diverging inlet only），and was further elevated to 79.33% with the combined design （diverging inlet and baffle）. Meanwhile， the particle settling rate in the hopper also improved， rising from 4.93% to 5.45% and then to 7.12% for the respective configurations，reflecting enhanced pre-separation of particles. Flow field analysis explained these improvements. The diverging inlet effectively reduced the velocity and momentum of the incoming jet. The perforated baffle further dissipated flow energy and suppressed direct impingement on the front filter bags，achieving a more uniform velocity across the entire filter array. Furthermore，the baffle was instrumental in weakening large-scale vortex structures and promoting a more even velocity distribution throughout the chamber. This optimized flow pattern resulted in a more balanced particle load distribution across all filter columns and improved filtration efficiency and dust handling capacity.
Conclusion The improved design incorporating a diverging inlet with a perforated flow distribution baffle minimizes direct impingement of particles on the front filter columns and promotes a more uniform velocity profile across the entire filter array. The baffle suppresses large-scale vortex formation and redirects airflow more evenly， resulting in a substantially more balanced distribution of the dust load among all filter columns.
Keywords：vertical bag filter； gas-solid two-phase flow； numerical simulation； structural optimization
Get Citation: Wu Xiaochen，Zhu Jiabin， Yang Juan，et al. Numerical simulation of gas-solid flow and structural optimization of a vertical bag filter［J］. China Powder Science and Technology， 2026，32（6）：1-14.
Received：2026-02-16，Revised：2026-05-07，Online：2026-05-12.
Funding： The research was supported by Shandong Province Science and Technology-based Small and Medium-sized Enterprises Innovation Capacity Improvement Project (Grant Nos. 2024TSGC0330, 2024TSGC0802) and the National Natural Science Foundation of China (Grant No. 51605192).
DOI：10.13732/j.issn.1008-5548.2026.06.008
CLC No.：TB44； TQ324.8
Type Code：A
Serial No.：1008-5548（2026）06-0001-14
