A chemical cleaning method and apparatus for scale buildup in nuclear power plant waste liquid evaporators

Abstract

This invention relates to a domestically pioneering chemical cleaning method and apparatus for scale removal from nuclear power plant waste liquid evaporators. The cleaning apparatus includes a heating chamber, a cleaning tank, and an evaporation chamber and a separation chamber of the nuclear power plant waste liquid evaporator. The heating chamber is connected via a conveying pipeline. The cleaning tank also has a fourth pipeline for pressure reduction. The composite acid in GJ-rust and scale remover can remove carbonate and metal oxide contaminants. The HF and glycolic acid in GJ-sparing scale chelating cleaner help dissolve stubborn silicate scale and metal oxide deposits, making them easier to remove from the surface. Considering that acid washing solution can corrode and damage the evaporator, metal corrosion inhibitors and metal reducing agents are added to ensure that the equipment metal is almost non-corrosive during chemical scale removal. Furthermore, appropriate heating is applied during cleaning to increase the reaction rate and fully dissolve the dirt. After removing the scale inside the evaporator, the surface of the internal components is passivated to form a metal passivation film on the equipment surface, extending the service life of the evaporator. After removing the scale, the evaporator's evaporation capacity is restored.

Description

Technical Field

[0001] This invention relates to the field of chemical cleaning, and in particular to a chemical cleaning method and apparatus for scaling on evaporators used in nuclear power plant waste liquid. Background Technology

[0002] Nuclear power plant waste liquid evaporators are used in waste liquid treatment systems. After years of operation, they suffer from severe scaling, reduced capacity, and poor heat exchange.

[0003] Upon inspection of the waste liquid evaporator, it was found that it was severely scaled and had lost most of its evaporation function, requiring replacement. However, the replacement equipment was expensive and involved complicated construction work such as disassembly, hoisting, etc., which would affect the operation and power generation.

[0004] Through sampling analysis, scale dissolution experiments, corrosion tests, and other methods, it is necessary to clean the scale thoroughly without causing corrosion to the equipment. Therefore, there is an urgent need for a chemical cleaning method that can effectively remove refractory scale from nuclear power plant waste liquid evaporators. Summary of the Invention

[0005] To address at least one of the technical problems existing in the background art, the present invention proposes a method and apparatus for chemical cleaning of insoluble scale in nuclear power plant waste liquid evaporators, which has a good cleaning effect.

[0006] A chemical cleaning method for scale buildup in a nuclear power plant waste liquid evaporator, the method comprising the following steps: S101, Compound Cleaning Agent: The product comprises: Component 1: 18-22% by weight of GJ-rust and scale remover, 0.3% of metal corrosion inhibitor, 0.2% of metal reducing agent, with the balance being water; Component 2: 4-6% by weight of GJ-insoluble scale chelating cleaner, with the balance being water. S102, Circulating scale removal: The components of the first component, weighed according to the weight, are mixed and stirred evenly at room temperature to form the first component mixture. The circulation pump is started, and the first component mixture is added to the cleaning device. The cleaning is carried out in a low-inlet and high-outlet manner. During the circulation cleaning process, the cleaning solution is gradually heated to 40-60℃. It mainly cleans calcium carbonate, magnesium hard scale and phosphate scale. S103, Precipitation and filtration: The cleaning agent is circulated through the cleaning tank via a pipeline. The cleaning tank contains a polyferric sulfate solution. A filter screen is installed at the outlet of the cleaning tank. The solution is then returned to the cleaning device via a pipeline and a circulation pump. S104. Acidity detection of cleaning agent: During the cleaning process, samples are taken from the cleaning solution at intervals to analyze the changes in acidity content. When the acidity content remains constant and the agent concentration is basically stable, meaning there is no carbonate dirt reacting with the agent, the preliminary cleaning is complete. S105. Add the prepared second component mixture to the cleaning device and continue using the circulation pump for 2-3 hours. Then, use an endoscope to inspect and confirm that the scale inside the equipment has completely dissolved, exposing the metal body. Next, turn off the circulation pump, open the valve on the cleaning tank to drain the wastewater, and then turn the circulation pump back on. Fill the cleaning device with clean water and continue rinsing and draining until the effluent is clear. This cleaning step mainly targets insoluble scale such as calcium silicate hard scale and rust nodules. S106. Passivation Protection: Add an oxidizing agent to the cleaning tank and dilute it to a concentration of 30-35% with chloride-free purified water. After uniform circulation, slowly heat the tank, controlling the temperature below 50℃, until a passivation film is completely formed. Confirm the formation of the passivation film using the blue dot method on standard corrosion test pieces. Circulate and soak for 3-4 hours, then drain. S107. Clean water rinsing: After passivation is completed, the cleaning device is rinsed with clean water until the pH value of the effluent is 6-7, and the cleaning is completed.

[0007] Preferably, the GJ-rust and scale remover comprises 90-95% compound acid and 5%-10% penetrant, and the GJ-sparing scale chelating cleaner comprises 20% HF acid, 10-15% glycolic acid, 5% metal chelating agent, and 5-10% penetrant. Preferably, the metal corrosion inhibitor is hydrazine, thiourea, or an organic nitrogen-containing compound, and the penetrant is fatty alcohol polyoxyethylene ether.

[0008] Preferably, the chelating agent is one or both of ethylenediaminetetraacetic acid and aminotriacetic acid.

[0009] Preferably, in steps S102-S104, the pH value of the cleaning agent is maintained at 0.5-1. During the scale removal cleaning process, the circulation pump is started, the cleaning agent circulates for half an hour, the circulation pump is stopped, and the cleaning agent is left to stand for half an hour.

[0010] Preferably, in step S102, the concentration of GJ-rust and descaling agent in the cleaning device is maintained above 6%; during the circulating descaling process, the concentration of GJ-rust and descaling agent is monitored every 1 hour, and if it is lower than 6%, the first component mixture is added.

[0011] Preferably, the first component comprises 20% by weight of GJ-rust and scale remover, 0.3% of metal corrosion inhibitor, 0.2% of metal reducing agent, and the balance being water; the second component comprises 4-6% by weight of GJ-insoluble scale chelating cleaner, and the balance being water.

[0012] As a preferred option, during the sedimentation and filtration process, the concentration of the polyferric sulfate solution in the cleaning tank is 5%, and the liquid level in the cleaning tank is not greater than three-quarters of the depth of the cleaning tank. The circulating water level in the solution preparation cleaning tank is kept at a low level to prevent the cleaning liquid from expanding and overflowing after heating.

[0013] A cleaning device for a nuclear power plant waste liquid evaporator includes a heating chamber, a cleaning tank, and a circulation system connecting the evaporation chamber and separation chamber of the nuclear power plant waste liquid evaporator. A first pipeline and a second pipeline are provided between the cleaning tank and the heating chamber. A circulation pump is provided on the first pipeline. The heating chamber and the separation chamber are connected by a conveying pipeline. A third pipeline connected to the cleaning tank is provided at the top of the separation chamber. A fourth pipeline is also provided in the cleaning tank for pressure reduction and flow regulation.

[0014] Preferably, the first pipeline is used to transport the cleaning fluid to the inlet of the heating chamber, the second pipeline is used to return the cleaning fluid at the top outlet of the heating chamber to the cleaning tank, and the third pipeline is used to return the cleaning fluid at the top outlet of the evaporation chamber and the separation chamber to the cleaning tank. Valves are provided on the first, second, third and fourth pipelines.

[0015] The beneficial effects of this invention are: First, the cleaning agents include the compound acid in GJ-rust and scale remover, which can remove carbonate and metal oxide contaminants. The acidic cleaning agent dissolves carbonates and converts them into soluble forms, such as carbonic acid or other water-soluble salts. In addition, the HF acid and glycolic acid in GJ-insoluble scale chelating cleaning agent help dissolve stubborn silicate scale and metal oxide deposits, making them easier to remove from the surface. It can thoroughly clean the dirt on the evaporator without damaging it, and at a low cost; After removing scale buildup inside the evaporator, to prevent scale buildup from affecting the evaporator's evaporation capacity, a passivation film is added to the surface of internal components to extend the evaporator's service life. Polyferric sulfate precipitates and solidifies suspended solids such as phosphates dissolved in the cleaning agent. The precipitate is then trapped in the cleaning tank by a filter screen and discharged later. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention, making other features, objects, and characteristics of the invention more apparent. The illustrative embodiments of the invention, along with their descriptions, are used to explain the invention and do not constitute an undue limitation of the invention.

[0017] Figure 1 A schematic flowchart of the chemical cleaning method for scaling in nuclear power plant waste liquid evaporators provided by the present invention.

[0018] Figure 2 This is a schematic diagram of the intermediate detection process for the chemical cleaning method provided by the present invention.

[0019] Figure 3 This is a schematic diagram of a cleaning device for a nuclear power plant waste liquid evaporator provided in an embodiment of the present invention.

[0020] In the diagram: heating chamber 100; separation chamber 200; cleaning tank 11; first pipeline 12; circulating pump 121; second pipeline 13; third pipeline 14; fourth pipeline 15; valve 16; conveying pipeline 17. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0023] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Analysis of evaporator scale composition: Based on the weight composition, the main components are approximately carbonates and dicalcium phosphate (about 60%), acid-insoluble matter (silicates) (21%), magnesium phosphate (about 15%), and the remainder are other impurities.

[0026] Given that the equipment is made of stainless steel, the presence of some acid-insoluble substances (slow-dissolving scale) affects the descaling time and efficiency. Therefore, we screened over twenty cleaning agents and additives, conducting numerous scale-dissolving experiments. We ultimately decided to use GJ-2E rust and scale remover, which is essentially non-corrosive to stainless steel, combined with GJ-slow-dissolving scale chelating cleaner as the primary cleaning agent. This was followed by a chemical cleaning and pre-filming method using a high-concentration oxidizing inorganic acid for passivation.

[0027] This invention discloses a chemical cleaning method for scale buildup in nuclear power plant waste liquid evaporators.

[0028] like Figure 1-3 As shown: The specific steps include the following: S101, Compound Cleaning Agent: The product consists of the first component: 18-22% by weight of GJ-rust and scale remover, 0.3% of metal corrosion inhibitor, and the balance being water. The GJ-rust and scale remover is packaged in a solid bag and its main components include 90-95% compound acid and 5%-10% penetrant. During use, it is mixed with water and stirred. The compound acid is mainly used to dissolve carbonates, dicalcium phosphate, and magnesium phosphate. It has good overall water solubility, high corrosion inhibition rate, minimal damage to equipment, and a corrosion rate only 1 / 10 that of inorganic strong acids.

[0029] The second component includes 4-6% by weight of GJ-insoluble scale chelating cleaner, with the balance being water; the main components of GJ-insoluble scale chelating cleaner include 20% HF acid, 10-15% glycolic acid, 5% chelating agent, and 5-10% penetrant.

[0030] The metal corrosion inhibitor is hydrazine, thiourea, and organic nitrogen-containing compounds, and the penetrant is fatty alcohol polyoxyethylene ether.

[0031] The chelating agent used is aminotriacetic acid. The chelating agent complexes metal and its oxide scale and salt scale, transforming insoluble dirt into soluble compounds. In particular, the combination of organic acid and chelating agent effectively reduces the amount of organic acid used, reduces the corrosion rate of metal parts, and also improves the descaling rate.

[0032] In step S101, the preferred ratio of the entire cleaning agent is as follows: the first component includes 20% by weight of GJ-rust and scale remover, 0.3% of metal corrosion inhibitor, 0.2% of metal reducing agent, and the balance is water; the second component includes 4-6% by weight of GJ-insoluble scale chelating cleaning agent, and the balance is water.

[0033] S102, Circulating scale removal: The components of the first component, weighed according to the weight, are mixed and stirred evenly at room temperature to form the first component mixture. The circulation pump is started, and the first component mixture is added to the cleaning device. The cleaning is carried out in a low-inlet and high-outlet manner. During the circulating cleaning process, the cleaning solution is gradually heated to 40-60℃. In step S102 of this embodiment, the pH value of the cleaning agent is maintained at 0.5-1. During the scale removal cleaning process, the circulation pump is started, the cleaning agent circulates for half an hour, the circulation pump is stopped, and the cleaning agent is left to stand for half an hour.

[0034] The concentration of GJ-rust and scale remover in the cleaning device is maintained above 6%; during the circulating scale removal process, the concentration of GJ-rust and scale remover is monitored every 1 hour, and if it is lower than 6%, the first component mixture is added.

[0035] S103. Sedimentation and filtration: The cleaning agent is circulated through a pipeline through a cleaning tank containing a polyferric sulfate solution. Polyferric sulfate is added to the cleaning tank, and a filter screen is installed at the outlet of the cleaning tank. Polyferric sulfate precipitates and solidifies the phosphate dissolved in the cleaning agent. The precipitate is then trapped in the cleaning tank by a filter screen and discharged later.

[0036] The solution is returned to the cleaning device via pipelines and circulating pumps; the concentration of polyferric sulfate solution in the cleaning tank is 5-20%, and the liquid level in the cleaning tank is not greater than three-quarters of the depth of the cleaning tank. The circulating water level in the solution preparation cleaning tank is kept at a low level to prevent the cleaning liquid from expanding and overflowing after heating.

[0037] S104. Acidity test of cleaning agent: Samples are taken from the cleaning solution at intervals to analyze the change in acidity content. When the acidity content remains unchanged and the agent concentration is basically stable, that is, when no dirt reacts with the agent, the preliminary calcium carbonate and calcium phosphate cleaning is completed. S105. Add the prepared second component mixture to the cleaning device, continue using the circulation pump for 1-3 hours, then turn off the circulation pump, open the valve of the cleaning tank to drain the sludge, then turn on the circulation pump again, fill the cleaning device with clean water and work to rinse and drain the sludge until the effluent is clear; Analysis of the acidity content of the cleaning solution during sampling shows that when the acidity is basically stable, it takes about 5 to 8 hours to determine that there is no longer any reaction between the scale and the cleaning agent. The cleaning process is considered to have reached its end point. Endoscopic examination is then used to confirm that the scale has been cleaned.

[0038] It should be noted that the scale should be thoroughly cleaned before passivation.

[0039] S106, Passivation Pre-filming: Add a metal oxidizing agent to the cleaning tank, dilute it to a concentration of 30-35% with chloride-free purified water, circulate evenly, and then slowly heat it, controlling the temperature below 50℃, until a passivation film is completely formed. Circulate and soak for 3-4 hours, then drain. The quality of the pre-film is confirmed by the blue dot method on standard corrosion test pieces.

[0040] During passivation, the blue dot method is used to test the passivation effect of the stainless steel test piece until a passivation film is completely formed, thus completing the passivation process. The passivation film testing method is as follows: Prepare a solution by adding 1 gram of potassium ferricyanide (K3) [Fe(CN6)] to 3 ml of (65%~85%) nitric acid (HNO3) and 100 ml of water (preferably prepare fresh before use). Then, soak filter paper in the solution and attach it to the surface to be tested, or directly apply or drop the solution onto the surface. Observe the appearance of blue dots within 30 seconds. The presence of blue dots indicates a failure, while the absence of blue dots indicates a pass. This test should be performed after the acid-washed passivated surface has basically dried.

[0041] S107. Clean water rinsing: After passivation is completed, the cleaning device is rinsed with clean water until the pH value of the effluent is 6-7, and the cleaning is completed.

[0042] The liquid level in the cleaning tank should not exceed three-quarters of the tank's depth. The circulating water level in the solution preparation cleaning tank should be maintained at a low level to prevent the cleaning liquid from expanding and overflowing after heating.

[0043] A cleaning device for a nuclear power plant waste liquid evaporator. The entire cleaning device includes the entire evaporator system, comprising a heating chamber 100 and a separation chamber 200. The separation chamber 200 is used to house the nuclear power plant waste liquid evaporator, and the evaporation chamber of the nuclear power plant waste liquid evaporator is located within the separation chamber.

[0044] Cleaning fluid is pumped into the bottom of heating chamber 100, filling it completely. After heating, the fluid is transported to the separation chamber and then returned to the cleaning tank from the top of both chambers (low inlet, high outlet) to clean and descale the entire system. After the scale is completely removed, a passivation pre-filming process is applied to the entire system. This restores the evaporator to its original designed heat exchange efficiency and forms a corrosion-resistant passivation film on the stainless steel surface of the evaporator, extending the equipment's service life.

[0045] The chemical cleaning method for recalcitrant scale in nuclear power plant waste evaporators uses the following cleaning equipment, see [link / reference]. Figure 3The cleaning device includes a cleaning tank 11, and a first pipe 12, a second pipe 13, and a third pipe 14 are provided in the cleaning tank 11. The first pipe 12 is used to transport the cleaning liquid to the inlet of the heating chamber 100, the second pipe 13 is used to return the cleaning liquid at the top outlet of the heating chamber 100 to the cleaning tank 11, and the third pipe 14 is used to return the cleaning liquid at the top outlet of the separation chamber 200 to the cleaning tank 11. A circulation pump is provided on the first pipe 12, and a filter screen is provided between the first pipe 12 and the cleaning tank 11 to filter the precipitates of polyferric sulfate and phosphate.

[0046] Valves 16 are installed on the first pipeline 12, the second pipeline 13 and the third pipeline 14.

[0047] A first pipeline 12 and a second pipeline 13 are provided between the cleaning tank 11 and the heating chamber 100. A circulation pump 121 is provided on the first pipeline 12. A third pipeline 14 connected to the cleaning tank is provided at the top of the separation chamber.

[0048] The first pipeline 12 is used to transport the cleaning fluid to the inlet of the heating chamber 100, the second pipeline 13 is used to return the cleaning fluid at the top outlet of the heating chamber 100 to the cleaning tank 11, and the third pipeline 14 is used to return the cleaning fluid at the top outlet of the separation chamber 200 to the cleaning tank 11.

[0049] The heating chamber 100 and the separation chamber 200 are connected by a conveying pipe 17. The cleaning solution is heated to 40-60°C in the heating chamber and then conveyed to the separation chamber for reaction.

[0050] A fourth pipeline 15 is installed at the cleaning tank, and a valve 16 is installed on the fourth pipeline 15. The fourth pipeline is used to discharge waste liquid in the cleaning tank and to reduce pressure and adjust the flow rate.

[0051] Cleaning efficiency: The cleanliness of the evaporator can be assessed through endoscopic inspection, photography, video recording, or visual inspection by opening the top cover. These methods provide a relatively intuitive view of the cleaning effect and can be supplemented by chemical analysis. The cleaning endpoint is reached when the acidity of the solution reaches equilibrium. If necessary, high-pressure water jet rinsing can be used to remove residue, achieving a cleaning efficiency of over 95%, meaning the inner surface of the evaporator tubes is essentially free of scale and clean, and the surface passes visual inspection.

[0052] Corrosion rate: Corrosion rate monitoring was conducted using the on-site stainless steel strip loss method, with stainless steel corrosion less than 2 g / m²·h. Stainless steel test pieces were weighed before and after cleaning. A type 1 stainless steel test piece has a surface area of ​​28 square centimeters. Based on the weight loss in grams, the total corrosion per square meter and the corrosion rate per square meter per hour can be calculated to assess the corrosion impact of the chemical cleaning on the equipment.

[0053] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0054] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A chemical cleaning method for scale buildup in a nuclear power plant waste liquid evaporator, characterized in that, The method includes the following steps: S101, Compound Cleaning Agent: The first component includes: 18-22% by weight of GJ-rust and scale remover, 3% of metal corrosion inhibitor, and 2% of metal restorative agent. The first component is water, and the remainder is water. The second component is 4-6% by weight of GJ-insoluble scale chelating cleaning agent, with the remainder being water. S102, Circulating scale removal: The components of the first component, weighed according to the weight, are mixed and stirred evenly at room temperature to form the first component mixture. The circulation pump is started, and the first component mixture is added to the cleaning device. The cleaning is carried out in a low-inlet and high-outlet manner. During the circulating cleaning process, the cleaning solution is gradually heated to 40-60℃. S103, Precipitation and filtration: The cleaning agent is circulated through the cleaning tank via a pipeline. The cleaning tank contains a polyferric sulfate solution. A filter screen is installed at the outlet of the cleaning tank, and the solution is returned to the cleaning device via a pipeline and a circulation pump. S104. Acidity detection of cleaning agent: During the cleaning process, samples are taken from the cleaning solution at intervals to analyze the changes in acidity content. When the acidity content remains unchanged and the agent concentration is stable, that is, when there is no reaction between carbonate dirt and agent, the initial cleaning of calcium carbonate scale is completed. S105. Add the prepared second component mixture to the cleaning device to clean silicates, rust nodules, and insoluble scale. Continue using the circulation pump for 2-3 hours, using an endoscope to confirm that the scale inside the equipment has completely dissolved, exposing the metal body. Then, turn off the circulation pump, open the valve on the cleaning tank to drain the wastewater, and then turn on the circulation pump again. Fill the cleaning device with clean water and continue operating. Rinse and drain until the effluent is clear; S106. Passivation Protection: Add a metal oxidizing agent to the cleaning tank and dilute it to a concentration of 30-35% with chloride-free purified water. After circulating evenly, slowly heat the tank and control the temperature below 50℃ until a passivation film is completely formed on the metal surface. After circulating and soaking for 3-4 hours, use the standard corrosion test piece blue dot method to check and confirm the formation of the passivation film before draining the tank. S107. Rinsing with clean water: After passivation, rinse the cleaning device with clean water until the pH of the effluent is 6-7, at which point the cleaning is complete; The GJ-rust and scale remover comprises 90-95% compound acid and 5-10% penetrant, and the GJ-sparing scale chelating cleaner comprises 20% HF acid, 10-15% glycolic acid, 5% metal chelating agent, and 5-10% penetrant; The metal corrosion inhibitor is hydrazine, thiourea, and organic nitrogen-containing compounds, and the penetrant is fatty alcohol polyoxyethylene ether; The chelating agent is one or both of ethylenediaminetetraacetic acid and aminotriacetic acid; The first component includes 20% by weight of GJ-rust and scale remover, 3% of metal corrosion inhibitor, 2% of metal reducing agent, and the balance is water; the second component includes 4-6% by weight of GJ-insoluble scale chelating cleaner, and the balance is water. During the sedimentation and filtration process, the concentration of polyferric sulfate solution in the cleaning tank is 5%, and the liquid level in the cleaning tank is no more than three-quarters of the depth of the cleaning tank. The circulating water level in the solution preparation cleaning tank is kept at a low level to prevent the cleaning liquid from expanding and overflowing after heating.

2. The chemical cleaning method for scaling in nuclear power plant waste liquid evaporators according to claim 1, characterized in that, In steps S102-S104, the pH value of the cleaning agent is maintained at 0.5-1. During the scale removal cleaning process, the circulation pump is started, the cleaning agent circulates for half an hour, the circulation pump is stopped, and the cleaning agent is left to stand for half an hour.

3. The chemical cleaning method for scale buildup in nuclear power plant waste liquid evaporators according to claim 1, characterized in that, In step S102, the concentration of GJ-rust and scale remover in the cleaning device is maintained above 6%; during the circulating scale removal process, the concentration of GJ-rust and scale remover is monitored every 1 hour, and if it is below 6%, the first component mixture is added.

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