Foam breaking — key process in detoxification of kraft mill effluents by foam separation

Abstract

AbstractA study was undertaken to demonstrate on pilot plant scale the performance of a turbine foam breaking system and to develop the design parameters for large scale application.Among various configurations a 3‐blade vaned‐disc turbine was found to be optimal for foam breaking. Major process variables controlling foam breaking were system design, tip velocity, rotation speed, and foam load. A foam breaking system with only restricted liquid draw‐off performed 3 ‐ 16 times better than a conventional flow through system. A 38 cm diameter turbine operating at 1800 τ/min (3600 cm/s tip velocity) collapsed up to 1.2 m3/min (42 ft3/min) of foam.Design equations developed for sizing of foam breakers suggest that a 61 cm (2‐ft) diameter 21 kW turbine will collapse 4.7 m3/min of foam. For a 95 × 103m3/d foam separation plant, approximately 12 foam breakers are required. Capital costs are estimated at $108,000.