Self-cleaning effect and secondary swirling clean gas for suppressing particle deposition on vortex finder of gas cyclones

In order to suppressing the particle deposition on vortex finder, a series of gas cyclones with the secondary swirling clean gas were developed inspired by the gas purge effect. Effects of the width and extension length of the flow channel as well as the secondary inlet velocity and running time on the particle deposition pattern, the deposited particle mass and the cyclones’ performance were experimentally investigated, respectively. The results show that the ultrafine particles (Stokes number Stk < 0.0358) are mainly loose deposited on the walls under the secondary gas. Compare to the conventional cyclone with single tangential inlet, the total deposited particle mass of the improved cyclone has a maximum reduction more than 60%, and the collecting efficiency is increased up to 97.5% under the basically same pressure drop. The corresponding no-deposition area is increased by about 13%, and remains constant in spite of extending the running time. Moreover, an interesting phenomenon named “self-cleaning effect” of the vortex finder was captured for the gas cyclones, and mechanism of the secondary clean gas on the particle deposition is preliminarily analyzed. The results can deepen the understanding of the particle deposition on the vortex finder and guide the design of the anti-coking gas cyclones.

为抑制旋风分离器溢流管（vortex finder）内的颗粒沉积，受气体吹扫效应启发，本研究开发了一系列搭载二次旋流清洁气体的气体旋风分离器。研究分别实验考察了流道宽度、延伸长度、二次入口速度以及运行时间对颗粒沉积形貌、沉积颗粒质量以及旋风分离器性能的影响。结果表明，在二次气体作用下，超细颗粒（斯托克斯数Stk < 0.0358）主要以松散形式沉积于壁面。与传统单切向入口旋风分离器相比，改进型旋风分离器的总沉积颗粒质量最大降幅超过60%，且在压降基本一致的前提下，收集效率最高可达97.5%。其无沉积面积提升约13%，且即便延长运行时间，该无沉积区域面积也保持恒定。此外，本研究还观测到一种有趣的溢流管“自清洁效应”现象，并对二次清洁气体抑制颗粒沉积的机理进行了初步分析。本研究结果可加深对溢流管颗粒沉积现象的理解，为抗结焦型气体旋风分离器的设计提供指导。