Ice-pigging to reduce and remove fouling and to achieve clean-in-place

Experimental and theoretical work has been undertaken to investigate the clean-in-place, CIP, and fouling removal capability of a novel patented crushed ice pigging system. The 'pig' consists of crushed ice in water with a freezing point depressant. The void fraction is carefully controlled so that the ice/water mix moves like a solid plug in free flow areas, but is able flow like a fluid in constricted areas. The ice pig is able to flow in pipes with sharp bends, through orifice plates, through T's and even in plate heat exchangers. The experimental work evaluating the 'cleaning efficiency' of this system indicated that the ice pig could easily and efficiently remove 'soft' fouling; using a volume of ice typically less than one tenth of the volume of water. The fouling materials tested included jam and fats (food industry), toothpaste (personal hygiene products) and fine slit and sand (river water cooled exchangers). (C) 2002 Published by Elsevier Science Ltd.