Technological and environmental problems in the stabilization treatment of the main condenser cooling circuit by sulfuric acid

Abstract

The method of anti-scale stabilization treatment of cooling water of the circulating cooling system (CCS) with sulphuric acid to reduce the content of bicarbonate and carbonate ions allows to effectively reduce scale formation processes in power plant’s cooling systems. The results of the research and analysis of the sulphuric acid dosage to ensure the water-chemical regime of the reversible cooling system are presented in the example of the Rivne NPP. The analysis of the results of the control of the technology of stabilization treatment of cooling water with sulphuric acid was carried out, as the influence of the technological changes on the content of sulfate ions in the discharge water and the influence of the water discharge into a water body were evaluated. The sulphuric acid stabilization treatment makes it possible to neutralize the alkalinity caused by the content of bicarbonate and carbonate ions and to convert the proportion of calcium ions bound to bicarbonate and carbonate ions into a permanent hardness that is not prone to scale formation under the influence of temperature and has a lower tendency to scale formation. The use of sulphuric acid may be suitable for the optimal choice of water chemistry regime for scale reduction in CCS, according to the criteria of acidification of additional cooling water, which is the dosing criterion. The technological regimes for CCS stabilization treatment with sulphuric acid introduced at the Rivne Nuclear Power Plant (NPP) ensured a decrease in the use of sulphuric acid and a decrease in discharges into the water body by an average of 220 t/year, a decrease in the increase in the content of sulfate ions before the water intake and after the water discharge of the Rivne NPP, which correlates with a decrease in the amount of sulphuric acid used for CCS water treatment and a decrease in the environmental impact on the water bodies of the Styr River.