The Use Of Heat Tolerant Reverse OsmosisMembranes In Process CondensatePolishing

摘要

Ion exchange based approaches to condensate polishing have been used very successfully in steam cyclepower systems for many years. However, the recovery of 'dirty' condensate contaminated during its use in theprocess industry is difficult and often process specific. This is primarily due to the wide variety of contaminants inthese condensate streams. Until recently, the residual heat of the condensate had proven to be the barrier to theuse of Reverse Osmosis (RO) membranes in such systems. Development of thermally stable membranematerials and methods of construction that allow them to be operated at elevated temperatures were originallydemanded by the pharmaceutical industry to enable chemical free, high temperature sanitisation but thesecharacteristics also make RO membranes available for use in condensate recovery applications.Membranes offer many advantages in the treatment of effluent streams (such as chemical free removal ofdissolved contaminants and as a barrier to suspended solids) and in combination with other technologies therecovery of water suitable for high purity applications is possible. This paper discusses a 50 m3/hr (220 gpm)application of 'hot water' RO membranes in the recovery of steam condensate for use as boiler feed water. Themembrane choice and design considerations for the plant are discussed, and reference made to 16 months' ofoperational data, including water flux and rejection characteristics.