1. Introduction
Dust explosions pose a significant and ongoing risk to various industries that process flammable particles [1,2,3]. Such incidents can cause serious injuries to people and cause significant property damage. For example, in August 2014, an explosion occurred at an aluminum powder factory in Kunshan, Jiangsu Province, China due to an open fire, killing 75 people. Recently, a starch dust explosion occurred in Qinhuangdao, Hebei in 2021, resulting in 21 deaths and 47 injuries; in January 2024, a dust explosion occurred in a metal processing factory in Changzhou, Jiangsu, resulting in 8 deaths and many injuries. These incidents highlight the critical importance of effective dust management strategies in industrial environments. Minimizing the concentration of combustible dust in the air is critical to preventing such catastrophic events. This requires a concerted effort to implement strict dust control measures, strengthen safety procedures and develop a culture of safety awareness in departments vulnerable to dust explosion hazards.
Dust collection technology is critical to mitigating the risks associated with combustible dust in industrial environments [4].A variety of dust removal technologies can be used to improve air quality, such as mechanical dust removal, filtration technology, electrostatic dust removal, ultrasonic dust removal, pulse injection technology, etc. [5]corona dust removal technology [6]and Fischer-Tropsch synthesis [7]. Among them, mechanical dust removal stands out due to its wide range of applications, with the advantages of small space requirements, low construction costs, simple operation, and no need for moving parts. Specifically, cyclones are a subset of mechanical dust collection methods that play a vital role in industries ranging from petrochemicals to agriculture. These devices use centrifugal force created by rotating airflow to separate particles from the airflow. There are two main types of cyclones: conventional counterflow cyclones and direct flow (axial) cyclones.Counterflow cyclone separator uses tangential inlet to generate centrifugal force [8]the purified air is discharged upward through the outlet [9].In contrast, axial cyclones employ cyclone generators that maintain the original direction of the airflow, resulting in a lower pressure drop [10]. This characteristic, coupled with higher throughput and enhanced flexibility during separation, makes axial cyclones particularly effective in controlling combustible dust accumulation and reducing the risk of explosions.
The evaluation of axial cyclones mainly depends on two key indicators – separation efficiency and pressure drop – as the benchmark for evaluating technical performance.The origins of axial cyclone design can be traced back to Umney’s seminal model in 1948 [11]. Initially, the lower separation efficiency of axial cyclones compared with counterflow cyclones limited their application scope. Nonetheless, subsequent research efforts have mainly focused on enhancing the efficiency of axial separators. It has been established that the geometry of an axial separator has a profound impact on its filtration capacity. It is worth noting that the design of the swirl blades becomes a key factor, accounting for a large part of the total pressure loss, and also has a vital impact on the generation of centrifugal force and the separation efficiency.Innovations designed to improve axial cyclone performance stand out [12,13,14].Andreusi’s [15] The introduction of adjustable guide vanes tailored to inlet velocity, dust concentration and particle characteristics marks a major advance.Likewise, Trow’s Quest [16] The effect of tube diameter on separator efficiency was studied and the optimal length-to-length ratio was determined, highlighting the subtle relationship between structural size and performance.Dirkzwager’s research [17] It is further elucidated that an enhanced centrifugal force field can be achieved through reduced diameter designs, providing insights into optimizing the balance between efficiency and pressure management.
Experimental research is the cornerstone of cyclone technology advancement, providing unparalleled precision and reliability. Hsiao and Chen’s exploration of multistage cyclones highlighted the critical role of Reynolds and Stokes numbers on particle separation efficiency, pointing out that fluid dynamics and particle behavior are the basis for optimizing cyclone design [18].Similarly, Koffman’s study of 14 cyclones used in parallel showed that the collective efficiency dropped from 96% to 92.2%. This drop was attributed to changes in inlet velocity, thus emphasizing the importance of uniform airflow for maximum performance. [19]. Additionally, Akiyama’s research on the effects of changes in outlet structure on particle separation illustrates the complex relationship between design elements and functional efficacy.These studies not only deepen our understanding of cyclone mechanics but also guide the development of more efficient and reliable systems through focused modifications of design parameters [20].
Many scientists have conducted research aimed at improving the performance of vortex tube separators. However, existing methods result in increased pressure losses and reduced aerodynamic performance and energy efficiency. Therefore, analyzing the separation efficiency and pressure loss of a cyclone separator through numerical simulation methods is helpful in the design process. To gain a deeper understanding of internal gas-solid flow, the complex dynamics within the cyclone tube and the impact of various structural and operating variables on performance require further exploration. This study uses Computational Fluid Dynamics (CFD), enriched by particle wall collision and entropy generation models, to dissect the effects of blade number, morphology, exit angle, guide cone and exhaust pipe size, and exhaust pipe configuration modifications on vortex tubes energy dissipation, separation efficiency and entropy production. Our results provide some insights into the internal gas-solid two-phase flow structure, which helps to better understand the energy loss mechanism and influence the performance of the separator.
4.in conclusion
The separation performance of axial cyclone separators was studied A model based on the entropy production model. The effects of blade number, blade exit angle and blade shape on separation performance were considered. In addition, the effects of guide cone diameter, exhaust pipe diameter and exhaust pipe shape were also studied.
Numerical simulations show that higher performance axial cyclones can be achieved with appropriate structural design. Increase the number of blades, reduce the blade exit angle, and select the L blade form to improve separation efficiency. In addition, a larger guide cone diameter, a smaller exhaust pipe diameter, and a larger exhaust pipe inclination angle can also improve the separation efficiency. All these methods result in larger pressure drop and entropy production due to higher turbulence dissipation entropy and wall entropy, which are the main causes of energy loss. Our results provide new insights into the particle separation process and provide practical suggestions for improving the dust collection performance of industrial axial cyclones.