Water-Treatment, Corrosion, and Internal-Deposit Studies for Eddystone

Since water conditions could well decide whether the 5000-psi 1200-F Eddystone unit could be operated satisfactorily, every condition which might lead to a problem was given careful consideration. Tests at supercritical pressure indicated that a considerable amount of “soluble salts” deposited in the 850 to 950-F range when initially present at 2.0 ppm. Less deposition occurred with potassium salts than with sodium, but it was sufficient to make careful control of solids in the whole system imperative. This will be accomplished by demineralization of the make-up and by bypass demineralization of condensate as required. When present in the amount anticipated for Eddystone, even at 1200 F there was no measurable decomposition or deposition of salts. As to corrosion, proper control of dissolved oxygen and maintaining 10-ppb hydrazine and sufficient ammonia to give an 8.5 to 9.5 pH range, insured low metal pickup. Thus, deposition of metallic oxides in the boiler and turbine does not appear to be a problem. Corrosion tests and metallographic examination of the various alloys used indicate no harmful loss of metal or change in structure, hence no service-life problems are expected.