Pressure drop and collection efficiency of cyclone and impact separators in a CFB

Abstract

Experimental results of pressure drop and gas–solid separation of impact separators with three rows of impact blades with included angles (60°, 90° or 120°) in a cold CFB set-up of 102 mm×102 mm cross section are presented for two different samples of sand and they are compared with the same of a conventional reverse flow cyclone. The pressure drop increases with higher superficial velocity for all the solid separators including cyclone at a constant solid circulation rate. ‘Overall collection efficiency’ (ηoc) remains practically unaltered for the cyclone within the range of superficial velocity of the experiment while it decreases with higher superficial velocity for the impact separators. ‘Fractional collection efficiency’ (ηfc) of cyclone increases monotonically with grain size while that of the impact separator becomes minimum for an intermediate grain size. The collection efficiency of impact separator is comparable to that of cyclone for either very small or very large particles. Copyright © 1999 John Wiley & Sons, Ltd.