Passivation of hollow copper strands in a stator water cooling system

Abstract

A system for passivating a plurality of hollow copper strands in a stator water cooling system including; a first storage tank containing a cleaning solution, a second storage tank containing rinsing water; a third storage tank containing a passivation solution; a plurality of conduits connecting the first, second, and third storage tanks in a closed loop with the plurality of hollow copper strands; and an alkaline pump for pumping the cleaning solution, the rinsing water, and the passivation solution through the closed loop.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to stator water cooling systems for a generator and more particularly to passivation of hollow copper strands in a stator water cooling system against obstruction.BACKGROUND OF THE INVENTION[0002]High megawatt electrical power generators may have liquid cooling systems for their stator windings. Such a liquid cooling system may be known as a stator water cooling system (SWCS). Stator cooling fluid, e.g., oxygenated water whose dissolved oxygen content is recommended to be more than 2 ppm (parts per million, weight based), circulates through the SWCS to cool the stator windings. The cooling fluid removes heat from the stator windings generated by the high energy electrical current flowing through the stator windings. The SWCS includes a network of cooling passages throughout the stator and that extend between the stator windings. These cooling passages should remain open and free of obstructions to ensure a high flow of coo...

AI Technical Summary

Benefits of technology

The invention relates to a system and method for passivating a stator water cooling system with hollow copper strands. The system includes multiple storage tanks containing different solutions, such as cleaning, rinsing, and passivation solutions, as well as conduits that connect the tanks in a closed loop with the strands. The invention allows for the efficient and effective cleaning, rinsing, and passivation of the strands in a single, closed loop process. The technical effects of the invention include improved cooling efficiency, reduced fouling and corrosion, and improved overall performance of the stator water cooling system.

Problems solved by technology

Accumulated copper oxide deposits in the plurality of copper strands 102 may eventually obstruct the flow of the coolant, reducing the flow of cool fluid through the stator, and disrupting proper cooling of the stator winding assembly.

Cuprous oxides are reddish, loose, morphologically and chemically unstable, and thus are lost into the coolant stream in particulate forms.

Due to insufficient exposure or insufficient oxygen content (such as 25 ppb-250 ppb (parts per billion, weight based)) in coolant flow, they are found to be associated with the most rapid copper corrosion rate because of its morphological instability and constitute a large portion in the blockage deposit.

The prevention of forming loose cuprous oxide on the inner surfaces 103 of the plurality of copper strands 102 proves to be an economic challenge and laborious effort.

However, the level of oxygenation of water requires stringent control and consistent monitoring and adjustment during the generator operation where other key operating parameter maintenance is taken with priority.

However, even the inner surfaces 103 of the plurality of copper strands 102 have the clean and fresh copper surfaces, it would take weeks, if not a month to form desirable firm passivation layers with merely air exposure and yet its homogeneity and controlled time and thickness of the layer along axis of hollowed strands are not warranted.

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