Heat exchanger cleaning using ice pigging

Ice pigging is an innovative method of removing fouling from topologically complex and demanding ducts. The process involves pumping ice slurry, a mixture of ice particles and a liquidus containing a freezing point depressant, through the fouled duct. The slurry acts in a similar manner to a solid pig, displacing material downstream of it as well as applying shear and hence mechanical cleaning effort to the duct walls. However, the ice pig is also able to navigate complex topologies which include bends, change in flow areas, open valves and multiple path junctions. This makes the technology suitable for retrofitting to existing process installations with minimal disruption or alterations to the lines. Additional benefits of this technology include: increase in product recovery within the lines, reduction in downtime required for cleaning, reduction in the volume of effluent produced and hence reduction in cleaning water and effluent processing costs, and, reduction in the use of expensive and potentially environmentally harmful cleaning chemicals. Experimental evidence will be presented displaying the performance of the ice pig in different applications from simple pipe topologies to complex plate exchangers. The paper will also identify future applications and required development work to ensure the successful implementation of this new and potentially paradigm shifting technology.