ABSTRACT
Cyclones have been widely used for separating air borne particles from gases in a variety of engineering applications like mineral processing, petroleum refining, food processing, pulp and paper making, environmental cleaning, etc. A Cyclone is relatively simple to fabricate and it requires low maintenance and cost effective. Reverse flow cyclones have wide applications in industries as dust collectors. The main drawback of this device is the large pressure drops and requires a high energy. Uniflow cyclone, developed at the University of Western Ontario and studied in detail by Sumner et al. [1], Vaughan [2], and Gauthier et al. [3], which offer low pressure drops by restricting flow reversal. In uniflow cyclone, the centrifugal energy is imparted to particles by guided vanes installed at the entrance of the cyclone. It comprises of vortex finder, Annulus, Central core, and Vanes. The vortex finder is kept concentric to the cyclone. The dust is collected from the annulus and dust free air leaves the cyclone from the central core. Akiyama et al. [4] experimentally correlated the design and operational variables such as inlet velocity, density, cyclone diameter, radius, pitch etc. to pressure drop and collection efficiency. Ramachandran et al. [5] pioneered an attempt to arrive at a mathematical model that describes pressure drop and collection efficiency as a function of design and operating variables. Ashwani Malhotra [6] attempted the Studies on fine particle collection and pressure drop in uniflow cyclone. Maynard [7] studied an axial flow cyclone under laminar flow conditions and developed mathematical model for low Reynolds number. As per this model the efficiency at the vanes is dependent on the dimensions and the number of vane turns. Zhang [8] developed a model for a vane axial cyclone to predict the particle separation efficiencies both under laminar and perfect mixing flow conditions. The tangential air velocity, the diameters of the inner and outer tubes, length of the separation chamber, and vane angle have been considered in this model. Ramchaval [9] carried out experimental investigation to understand the effect of vane angle on tangential velocity and pressure drop in uniflow cyclones. However, the range of vane angles studied is very limited. In the present study, vanes of different angles have been fabricated and developed a uniflow cyclone unit to predict the optimum vane angle for low pressure drop, high tangential velocity and developed a methodology for measuring the tangential velocity. The experiments were conducted for different inlet velocities ranging from 4 to 13 m/s and at different vane angles between 20° to 60°.
