Water Deaeration in Water-Cooling Systems of the Stator Winding in a Turbogenerator with Hydrogen-Water Cooling

Resumo

Results of experimental investigations performed on 210–1200 MWel. power units at thermal and nuclear power stations yielded a statistical correlation of the corrosion rate for cooled copper conductors in water-cooling systems of the stator winding in a hydrogen-water cooled generator vs. cooling water quality characteristics, such as electrical conductivity, pH, and dissolved oxygen content. The content of dissolved oxygen in the cooling water is found to have a pronounced effect on the efficiency of corrosion protection of system elements. An engineering solution is proposed. It calls for installation of a small cavitation deaerator operating on superheated water in the cooling water return pipeline from the turbogenerator stator winding to a vacuum tank from which steam is removed by the main ejector of the turbine unit condenser or the deaerator’s own ejector. Special experimental investigations allowed the determination of the water deaeration efficiency in deaerators of the considered type. It is described by a dependence of a relative decrease in the content by weight of oxygen dissolved in the deaerated water on the water overheating at the deaerator inlet with reference to saturation temperature corresponding to the pressure in the steam suction pipeline. It was established by calculations that the proposed engineering solution decreased the corrosion rate of copper conductors in water-cooling systems of the stator winding, on average, by a factor of 2.1. Results of this investigation can be used in designing new power facilities or retrofitting process systems of operating hydrogen-water cooled turbogenerators.