Alternative Inhibitors for Ammonia/Water Refrigeration Machines. Final Report,July 1990-June 1992

摘要

The report presents the test results on two inorganic compounds chosen asenvironmentally safe alternatives to the sodium chromate corrosion inhibitors that is currently used to protect carbon steel surfaces in ammonia/water refrigeration machines. At the request of GRI, the identity of the alternative corrosion inhibitors is being withheld and are referred to as Type-A and Type-B throughout the report. These compounds were selected from a larger group of compounds for testing in standard, residential 3-ton ammonia water chillers after they had been screened for their effectiveness by electrochemical techniques and coupon immersion tests in autoclaves. The test results indicated that the Type-A corrosion inhibitor performed better than Type-B and produced no more non-condensables than the chromate inhibited chillers after 50 days of continuous testing. Cracks near welds that caused early failure of both test chillers were not related to the alternative inhibitors but was likely the result of the atypical chiller surface pretreatment used in these tests. Replacing the generator's heat exchanger coil with a more corrosive resistant alloy would also reduce the amount of corrosion and non-condensable gas generation.