Effectiveness of the ion exchange/vacuum dehydration treatment of phosphate ester fluids

摘要

Phosphate ester fluids are used in the electrohydraulic control systems of steam turbines. Conditioning agents are often added to the fluids to help prevent their pelformance being degraded by factors such as hydrolytic breakdown. However, some conditioning agents contain extractable metals that can react to form phosphate soaps or salts, which are also detrimental to the fluids' performance. This paper reports on the nature, origin, and mechanism of formation of these contaminants, with particular regard to those found on 'last chance' and high-pressure system filters and in the phosphate ester fluids used by utility companies. Ion exchange/vacuum dehydration (IX/VD) treatment has been found to be effective in removing water, particulates, acid, and phosphate soaps from phosphate ester fluids. Three case studies are outlined wherein the IX/VD treatment of phosphate ester fluids was used to restore the fluids to their original specification. IX/VD treatment is shown to be a cost-effective means of phosphate ester conditioning.