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Chemical cleaning agent and cleaning method for water vapor system of secondary circuit of high temperature gas-cooled reactor nuclear power unit

A technology for high-temperature gas-cooled reactors and nuclear power units, which is applied in the field of chemical cleaning of nuclear power units, and can solve problems such as large deviation of material grades, difficulty in segmental cleaning, and stress corrosion of sealing surface galvanic couples.

Active Publication Date: 2022-03-25
XIAN THERMAL POWER RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the secondary circuit system of the HTGR nuclear power unit is complex, with many types of pipe materials and large differences in pipe diameters. The requirements for the cleaning medium, cleaning process, and water vapor quality after cleaning are more stringent; secondly, the secondary circuit of the HTGR has no superheater and The reheater is difficult to clean in sections, and the water supply and steam pipes are cleaned in series as a whole, which leads to large deviations in material grades during the cleaning process, and is prone to pitting corrosion of different metal materials, intergranular corrosion of austenitic steel, stress corrosion and sealing surfaces Occurrence of localized corrosion such as galvanic corrosion

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] According to mass percentage, it is composed of 3.0% descaling agent, 0.3% isotridecanol polyoxyethylene ether penetrant, 0.3% thiourea-triazole compound corrosion inhibitor, 0.2% ascorbic acid reducing agent and demineralized water , ammonia water to adjust the pH value of the cleaning agent to 3.5.

[0019] The descaling agent is composed of the following mass percentages: 50% of citric acid, 20% of gluconic acid, 10% of ethylenediaminetetraacetic acid, and 10% of 2-hydroxysuccinic acid.

[0020] Take 200mL of the cleaning agent in this example, raise the temperature to 95°C, clean the SA-106C, P265GH, T22 and P91 spare tube samples under airtight conditions, clean for 24 hours, after cleaning, remove the SA-106C, P265GH and T22 tubes. The scale rates were 99.2%, 98.7% and 98.3% respectively. The scale removal rate of the P91 tube was 95.2%, the chromium-rich layer at the bottom of the P91 was retained, and the cleaning residue rate was 4.3%.

Embodiment 2

[0022] According to mass percentage, it contains 10% of scale remover, 0.3% of isomeric tenol polyoxyalkyl ether penetrant, 0.3% of s-triazole ring triazole compound corrosion inhibitor, 0.2% of acetone oxime reducing agent and It is composed of demineralized water and ammonia water to adjust the pH value of the cleaning agent to 4.0.

[0023] The descaling agent is composed of the following mass percentages: 60% of citric acid, 15% of gluconic acid, 15% of ethylenediaminetetraacetic acid, and 10% of 2-hydroxysuccinic acid.

[0024] Take 200mL of the cleaning agent in this example, raise the temperature to 85°C, clean the SA-106C, P265GH, T22 and P91 spare tube samples under airtight conditions, clean for 24 hours, after cleaning, remove the SA-106C, P265GH and T22 tubes. The scale rate is 100%, the scale removal rate of P91 pipe is 96.8%, the chromium-rich layer at the bottom of P91 is retained, and the cleaning residue rate is 0.3%. SA-106C, P265GH, 12Cr1MoV, P91 corrosion ...

Embodiment 3

[0026] According to mass percentage, it contains 20% scale remover, 0.5% fatty alcohol polyoxyethylene ether penetrant, 1.0% Schiff base-triazole compound corrosion inhibitor, 0.2% hydroquinone reducing agent and desalted water Composition, hydrazine adjusts the pH of the cleaning agent to 4.5.

[0027] The descaling agent is composed of the following mass percentages: citric acid accounts for 70%, gluconic acid accounts for 10%, ethylenediaminetetraacetic acid accounts for 10%, and 2-hydroxysuccinic acid accounts for 10%.

[0028] Take 200mL of the cleaning agent in this example, heat it up to 65°C, and clean it for 24 hours under airtight conditions. After cleaning, SA-106C, P265GH, 12Cr1MoV and P91 corrosion indicator pieces have no point corrosion, and the corrosion rate is 0.38g / ( m 2 h), 0.29g / (m 2 h), 0.32g / (m 2 h) and 0.24g / (m 2 h), Super304H corrosion indicator sheet and loaded stress sample can not observe intergranular corrosion and stress corrosion under 500 ti...

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Abstract

The invention provides a chemical cleaning agent and a cleaning method for the water vapor system of the secondary circuit of a high-temperature gas-cooled reactor nuclear power unit. ~1.0% corrosion inhibitor, 0.05~0.5% reducing agent, pH regulator and desalinated water. The scale dissolver is used to remove rust products and oxide scales, the penetrating agent is used to promote the acidic medium to enter the inside of the rust products and oxide scales, the corrosion inhibitor is used to control the corrosion of the metal substrate, and the reducing agent is used to inhibit the corrosion of the metal substrate by ferric iron ; The cleaning method is to control the pH of the cleaning agent to 3.0 to 5.5, and to control the cleaning temperature to 65 to 95°C. The cleaning agent and cleaning method have good solubility for rust products and oxide scales, and can control the corrosion of metal substrates within the acceptable range and safety range of the design, and completely inhibit pitting corrosion, intergranular corrosion, stress corrosion and galvanic corrosion localized corrosion of the metal substrate.

Description

technical field [0001] The invention belongs to the technical field of chemical cleaning of nuclear power units, and in particular relates to a chemical cleaning agent and a process for a secondary circuit water vapor system of a high-temperature gas-cooled reactor nuclear power unit. Background technique [0002] High-temperature gas-cooled reactor is the fourth generation of nuclear power technology. It is an advanced reactor type with inherent safety. It has broad application prospects in power generation, heating, hydrogen production, seawater desalination and other fields. [0003] Compared with the pressurized water reactor nuclear power unit, the steam pressure and temperature of the secondary side outlet of the high temperature gas-cooled reactor are 14.3MPa and 570℃, respectively, which are much higher than 6.71MPa and 283℃ of the pressurized water reactor, and the material grade is also higher; secondly, The high temperature gas-cooled reactor steam generator has a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C23G1/08C23G1/06
CPCC23G1/088C23G1/065C23G1/061
Inventor 张贵泉
Owner XIAN THERMAL POWER RES INST CO LTD