Efficiency of Antiscalants in Industrial Cooling Water Systems

Abstract

In many industrial operations formation of deposits on heat exchanger surfaces and other cooling systems is a persistent problem. These deposits contain mineral scales (CaCO3, CaSO4, Ca3 (PO4)2, CaF2 etc.), corrosion products (Fe2O3, Fe3O4, Cuo etc.), particulate matter (clay, silt etc.) and microbiological mass. Deposition of these materials on heat exchange surfaces lead to loss of system efficiency, overheating, unscheduled shutdown and ultimately failure of heat exchangers. In cooling and boiler water systems, these deposits normally accumulate in low circulation areas and may become immobilized during upset conditions resulting in buildup of deposits on heat exchangers. An effective cooling water treatment must control scale, particulate matter and corrosion. Over the years, a variety of antiscaling agents have evolved including acid/chromate, zinc/chromate, stabilized phosphonate, phosphate/zinc/polymer and all organic. Phosphonates are excellent calcium carbonate inhibitors or antiscalants which reduce the scale formation in cooling water systems. Determination of efficiency of these antiscalants is also important before using them. Techniques (Boffardi, ONGC) presently used for determining their efficiency do not provide consistent results, these methods are time consuming and also difficult to execute. Industries are facing problem in finding the optimum dosage ofantiscalant in cooling water systemswith a peculiar composition. So, a technique based on the theoretical considerations has been given herein, which produces consistent results in an easy way and requires less time to perform using cooling system water.