Method for adjusting pH value of secondary circuit of nuclear power plant

Abstract

The invention provides a method for adjusting the pH value of a secondary circuit of a nuclear power plant. The technical scheme is that: an ethanolamine solution is taken as a pH value adjusting agent; and the pH value of condensate is adjusted to 9.20-9.30 at the temperature of 25 DEG C before the condensate enters a subsequent secondary circuit moisture cycle. Due to the adoption of the method, the pH value of a liquid phase of a gas-liquid two-phase position is increased, a corrosion product of liquid-phase area equipment in gas and liquid phases is reduced, the corrosion state of a secondary circuit system is improved, the transfer amount of a water supply system corrosion product to the secondary side of a stream generator is reduced, the depositing probability of the corrosion product inside the stream generator is lowered, and the service life of the steam generator is prolonged; and moreover, the periodical water output of a water condensing mixed bed of a condensate precise treating device is increased, the regenerating times of the water condensing mixed bed, the using amounts of regenerated acids and alkalis and the water consumption are reduced, the workload of running personnel is relieved, and the discharge of a regenerated water liquid into the environment is reduced.

Description

technical field [0001] The invention belongs to the field of nuclear electrochemistry, and in particular relates to a novel pH regulator for slowing down the corrosion of the secondary loop system of a nuclear power plant. Background technique [0002] Qinshan Nuclear Power Co., Ltd.'s 310MWe steam generator heat transfer tube is made of Incoloy800 alloy, and its conventional island secondary circuit system has been using ammonia (NH 3 ·H 2 O) As a pH regulator, the pH value of the condensed water is controlled within the range of 9.30 to 9.50 at 25°C. Due to the large vapor-liquid partition coefficient of ammonia, such a low concentration of ammonia cannot guarantee the steam condensate at the vapor-liquid phase transition, that is, the pH value of the liquid phase is alkaline at 25°C, resulting in various extraction system pipes, The obvious acid corrosion in the steam-water separator drain pipe and other areas makes the iron content of the secondary circuit feed water h...

AI Technical Summary

Problems solved by technology

Due to the large vapor-liquid distribution coefficient of ammonia, such a low concentration of ammonia cannot guarantee the steam condensate at the vapor-liquid phase transition, that is, the pH value of the liquid phase is alkaline at 25°C, resulting in various extraction system pipes, The obvious acid corrosion in the steam-water separator drain pipe and other areas makes the iron content of the secondary circuit feed water higher, and these corrosion products will be further transferred to the steam generator, causing iron scale on the heat transfer tube or tube plate of the steam generator form

Therefore, without changing the pH regulator, in order to reduce the corrosion of the drainage pipes and the water supply system, and reduce the iron content of the feed water, it is necessary to add more ammonia to increase the pH value of the secondary circuit. As the amount of ammonia increases, the operation period of the condensate mixed bed of the condensate polishing device will be significantly shortened, and the frequency of resin regeneration will increase, resulting in a substantial increase in the workload of the operators. In order to keep the workload of the operators within an appropriate range Inside, the condensate treatment method needs to be adjusted, from the original condensate full flow treatment to partial flow treatment

In this mode of operation, the impurities in the condensed water, including corrosion products and condenser leakage, cannot be completely removed, making the condensed water quality worse and further affecting the feed water quality

At present, there is no report on the pH value adjustment method that takes into account the corrosion of the water supply system and the normal treatment of condensed water.

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