PRELIMINARY INVESTIGATIONS INTO A PHOTOMETRIC ABSORBANCE METHOD AS AN OPTION FOR DETECTING CONDENSATE CONTAMINATION

CONTAMINATION of boiler feed water by process materials can result in issues with boiler priming, corrosion, scaling and water treatment costs. Electrical conductivity (EC) monitoring is the standard method of contamination detection across most Australian raw sugar factories. While being simple, quick and relatively cheap, there are limitations to its effectiveness. The majority of material present in sugar mill products results in little or no change in EC, and relatively high concentrations of high purity materials can occur before appreciable changes in EC are detected. Alternate methods of detection typically require complex equipment, reagents, calibration, and time for analysis to be completed compared to the EC method. Ideally a monitoring method should return results in real time, allowing simpler diversion of contaminated waters. Some organic substances absorb UV radiation, and absorbance methods have found application in water and wastewater monitoring as a surrogate in organic content measurement. This project sought to determine if the absorbance characteristics of condensates and solutions of process materials might offer the opportunity to use an on-line or at-line process photometer for contamination detection. Condensates and solutions of process materials had their EC and absorbance determined at wavelengths between 190 and 1 100 nm. Relatively strong absorbance was found to occur in the ultraviolet (UV) region when process materials were present. There were similarities between the UV absorbance response of process materials and their EC, in that levels of both tended to increase with decreasing purity. As a result, an UV absorbance method would suffer from similar problems to the conventional EC method. It would not be as effective on higher purity materials, nor quantify the amount of contamination present. However there were indications an UV absorbance method may be more sensitive to process material contamination than the conventional EC method. It is anticipated that further work will occur in 2009 with a view to developing and evaluating an on-line or at-line condensate monitoring system using an UV absorbance method.