A Novel Design to Overcome Detrimental Effect of High‑Temperature Operating Conditions on Separation Efficiency of Square Cyclone

In this research, a numerical study was conducted to analyze a novel design for overcoming the detrimental effect of high‑temperature operating conditions on the separation efficiency of a square-based cyclone. This kind of cyclone can be utilized in the Circulating Fluidized Bed (CFB) boiler and it was shown to become one of the most appropriate cleaning tools for high-temperature gases. Previous studies found that the separation efficiency of a cyclone reduced remarkably with the increment of inlet temperature resulting in weaker swirling flow over cyclones at extremely high temperatures. Hence, it is vital to develop an effective approach to prevent this detrimental impact. The novel cyclone design is based on the idea of altering the inlet shape on the flow field and enhancing the cyclone collecting efficiency in high‑temperature operating conditions. Three separate inlet configurations, namely flat, oblique, and curved inlets were particularly developed and investigated numerically through the Computational Fluid Dynamics (CFD) method to maximize the low separation efficiency of a square cyclone influenced by the high‑temperature operating condition. For simulating the flow of particles, the Eulerian-Lagrangian methodology is implemented for solving Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. The Discrete Random Walk (DRW) is utilized for modeling fluctuations of velocity. Numerical results indicated that using oblique and curved inlets generated a raising in pressure drop but they significantly improved the separation efficiency of the cyclone separator. Among all inlet shapes, oblique inlet dramatically enhanced the separation efficiency by up to 15% at an inlet velocity of 12 m/s.