Chemical cleaning corrosion inhibitor desorbent

Abstract

The application discloses a chemical cleaning corrosion inhibitor desorption agent and belongs to the technical field of chemical cleaning. The desorption agent is composed of 15-25% alkalizer, 0.1-1.0% solubilizer and desalted water. The corrosion inhibitor used in the chemical cleaning process is adsorbed on the metal surface and is difficult to be washed out of the system by water. During the start and operation of the unit, the corrosion inhibitor is gradually desorbed and decomposed, which leads to the problems of over-standard water vapor hydrogen conductivity, unqualified water quality for a long time and the like. After the chemical cleaning is completed, the desorption agent is added during the water washing work, so that the desorption of the corrosion inhibitor is promoted, the corrosion inhibitor is taken out of the system with the water washing, and the problems of over-standard unit water vapor hydrogen conductivity caused by the adsorption of the corrosion inhibitor are solved.

Description

Technical Field

[0001] This invention belongs to the field of chemical cleaning technology, and specifically relates to a chemical cleaning corrosion inhibitor desorbent. Background Technology

[0002] During the chemical cleaning of boiler heating surfaces, corrosion inhibitors need to be added to reduce the corrosion of the metal by the acidic cleaning medium. Currently, the commonly used corrosion inhibitors for boiler chemical cleaning are adsorption film type organic corrosion inhibitors. The corrosion inhibitor molecules contain polar and non-polar groups. Polar groups (such as amino, carboxyl, and mercapto groups) can form a monomolecular film on the metal surface through physical adsorption or chemical adsorption, while non-polar groups have hydrophobic effects, which can slow down the electrochemical reactions on the metal surface and slow down the corrosion of the metal.

[0003] After chemical cleaning, water rinsing (rinsing temperature 20-60℃) is usually required. Currently, the main indicators for determining the endpoint of water rinsing are iron ion content and pH value. Even after the iron ion content and pH value are within acceptable limits, some corrosion inhibitors adsorbed on the metal surface are still difficult to flush out of the system. During unit startup and operation, the corrosion inhibitors gradually desorb and decompose, leading to excessive water vapor hydrogen conductivity and substandard water quality for an extended period. Furthermore, corrosion inhibitor adsorption can also cause problems such as excessive water vapor hydrogen conductivity in the unit. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a chemical cleaning corrosion inhibitor desorbent that can promote the desorption of corrosion inhibitors and carry them out of the system with water rinsing, thereby solving problems such as excessive water vapor hydrogen conductivity in the unit caused by corrosion inhibitor adsorption.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of the present invention is to provide a chemical cleaning corrosion inhibitor desorbent, comprising, by mass percentage: 15% to 25% alkalizing agent, 0.1% to 1.0% solubilizer and the balance being demineralized water.

[0007] As a further improvement of the present invention, the alkalizing agent includes one or both of ammonia or hydrazine.

[0008] As a further improvement of the present invention, the solubilizer includes one or more of the following types: polyoxyethylene type, polyol type, polyether type, and alkanolamide type.

[0009] As a further improvement of the present invention, the hydrophilic-lipophilic balance value (HLB) of the solubilizer is greater than 15.

[0010] As a further improvement of the present invention, the chemical cleaning corrosion inhibitor desorbent comprises, by mass percentage: 20% to 25% alkalizing agent, 0.1% to 0.3% solubilizer and the balance being demineralized water.

[0011] A second aspect of the present invention is to provide a method of using a chemical cleaning corrosion inhibitor desorbent, comprising:

[0012] After the chemical cleaning of the power plant is completed, a desorbent is added during the water flushing process. Under the action of the desorbent, the corrosion inhibitor is desorbed and carried out of the system with the water flushing.

[0013] As a further improvement of the present invention, the total iron content in the system before the desorbent is added does not exceed 300 mg / L.

[0014] As a further improvement of the present invention, the amount of desorbent added must ensure that the pH value of the solution in the system is not lower than 10.0.

[0015] As a further improvement of the present invention, the temperature at which the desorbent is added is 80-95°C, the circulation flow rate is 0.1-1.0 m / s, and the time is 0.5-2 hours.

[0016] As a further improvement of the present invention, it also includes: performing water quality analysis on water samples within the system and measuring the TOC of the water samples within the system.

[0017] The technical solution provided by this invention has the following beneficial effects:

[0018] This invention provides a chemical cleaning corrosion inhibitor desorbent, composed of an alkalizing agent, a solubilizer, and demineralized water. The alkalizing agent provides an alkaline environment to promote the desorption of the chemical cleaning corrosion inhibitor from the metal surface, while preventing rust re-emergence on the metal surface after cleaning. The solubilizer promotes the dissolution of surfactants, increasing the desorption rate of the corrosion inhibitor. This desorbent has good desorption effects on both physically and chemically adsorbed corrosion inhibitors, promoting their desorption and removal from the system by water flushing, thus solving problems such as excessive hydrogen conductivity in the unit's water vapor caused by corrosion inhibitor adsorption. The chemical cleaning corrosion inhibitor desorbent provided by this invention has good water solubility, does not adsorb onto the metal surface, and is easily flushed out of the system during water flushing, saving water consumption and not affecting the water vapor quality during startup and operation. The chemical cleaning corrosion inhibitor desorbent provided by this invention can prevent rust re-emergence on the metal surface during water flushing. Detailed Implementation

[0019] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, the terms “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of”. For example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a”.

[0023] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0024] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both mean: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple.

[0025] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0026] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0027] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0028] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] The first objective of this invention is to provide a chemical cleaning corrosion inhibitor desorbent, which is composed of 15% to 25% by mass of an alkalizing agent, 0.1% to 1.0% by mass of a solubilizer and a deionized water solution.

[0031] Preferably, the chemical cleaning corrosion inhibitor desorbent may further include, by mass percentage: 20% to 25% alkalizing agent, 0.1% to 0.3% solubilizer, and the balance being demineralized water.

[0032] Alkalinizing agents are used to provide an alkaline environment, which promotes the desorption of chemical cleaning corrosion inhibitors from the metal surface and prevents the metal surface from rusting again after cleaning; solubilizers are used to promote the dissolution of surfactants and increase the desorption rate of corrosion inhibitors.

[0033] Corrosion inhibitors used in chemical cleaning processes can adhere to metal surfaces and are difficult to flush out of the system with water. During unit startup and operation, the corrosion inhibitors gradually desorb and decompose, leading to problems such as excessive water vapor-hydrogen conductivity and substandard water quality for extended periods.

[0034] The alkalizing agent acts to provide an alkaline environment, promoting the desorption of the chemical cleaning corrosion inhibitor from the metal surface, while preventing the metal surface from rusting again after cleaning. It is composed of one or more of ammonia or hydrazine.

[0035] The solubilizer is used to promote the dissolution of surfactants and improve the desorption rate of corrosion inhibitors. It is composed of one or more of polyoxyethylene type, polyol type, polyether type, and alkanolamide type, and its hydrophilic-lipophilic balance value (HLB) is greater than 15.

[0036] The second objective of this invention is to provide a chemical cleaning corrosion inhibitor desorbent, the method of which is as follows:

[0037] After the chemical cleaning of the power plant is completed, a desorbent is added during the water flushing process. Under the action of the desorbent, the corrosion inhibitor is desorbed and carried out of the system with the water flushing.

[0038] After chemical cleaning, when water rinsing is carried out, adding a desorbent can promote the desorption of the corrosion inhibitor and carry it out of the system with the water rinse, thus solving problems such as excessive water vapor hydrogen conductivity caused by corrosion inhibitor adsorption.

[0039] Before adding the desorbent, the total iron content in the system should not exceed 300 mg / L; the amount of desorbent added should ensure that the pH value of the solution in the system is not lower than 10.0; the operating temperature is 80-95℃, the circulation flow rate is 0.1-1.0 m / s, and the time is 0.5-2 hours.

[0040] The present invention will be further described in detail below with reference to specific embodiments.

[0041] Example 1:

[0042] The water-cooled wall tubes of a power plant, after chemical cleaning, were installed on a dynamic test bench for desorption and flushing tests: demineralized water was added to the system, and desorbent was added to adjust the pH value to 10.5. The temperature was raised to 90℃, the circulation flow rate was 0.5m / s, and the circulation desorption time was 1 hour.

[0043] After the desorption test, the system was emptied and a flushing test was conducted: the system was replenished with demineralized water, heated to 25°C, and circulated at a flow rate of 0.5 m / s for 1 hour. Then, the water sample from the system was analyzed to measure its TOC (Total Organic Carbon, which directly reflects the amount of adsorbed organic corrosion inhibitor). Simultaneously, a comparative test (the desorption and flushing test conditions were the same as the above tests, except that no desorbent was added) and a blank test (no desorption test, only a flushing test) were performed.

[0044] The desorbent consists of 20% by mass of alkalizing agent, 0.1% of solubilizer and 79.9% of demineralized water, wherein the alkalizing agent consists of 80% ammonia and 20% hydrazine, and the solubilizer is Pingpingjia.

[0045] Table 1. Water quality conditions of Example 1, blank test, and comparative test.

[0046] Test Name TOC / (mg / L) blank test 98.0 Comparative test 80.5 Example 1 5.0

[0047] By comparison, it can be seen that the TOC content of Example 1 of the present invention is significantly lower than that of the comparative example, and the amount of adsorbed organic corrosion inhibitor is extremely low, at 5.0 mg / L. Therefore, Example 1 can promote the desorption of corrosion inhibitor.

[0048] Example 2:

[0049] The superheater tubes of a power plant, after chemical cleaning, were installed on a dynamic test bench for desorption and flushing tests: demineralized water was added to the system, and desorbent was added to adjust the pH value to 10.6. The temperature was raised to 95℃, the circulation flow rate was 1.0 m / s, and the circulation desorption time was 2 hours.

[0050] After the desorption test, the system was emptied and a flushing test was conducted: the system was replenished with demineralized water, heated to 25°C, and circulated at a flow rate of 0.5 m / s for 1 hour. Then, the water sample from the system was analyzed to measure its TOC (Total Organic Carbon, which directly reflects the amount of adsorbed organic corrosion inhibitor). Simultaneously, a comparative test (the desorption and flushing test conditions were the same as the above tests, except that no desorbent was added) and a blank test (no desorption test, only a flushing test) were performed.

[0051] The desorbent consists of 25% by mass of alkalizing agent, 0.3% by mass of solubilizer and 74.7% by mass of deionized water. The alkalizing agent consists of 60% ammonia and 40% hydrazine, and the solubilizer is Pingpingjia.

[0052] Table 2. Water quality conditions in Example 2, blank test, and comparative test.

[0053] Test Name TOC / (mg / L) blank test 126.0 Comparative test 120.5 Example 2 8.0

[0054] By comparison, it can be seen that the TOC content in Example 2 of the present invention is significantly lower than that in the comparative example, and the amount of adsorbed organic corrosion inhibitor is extremely low, at 8.0 mg / L. Therefore, Example 2 can promote the desorption of corrosion inhibitor.

[0055] Example 3:

[0056] The superheater tubes of a power plant, after chemical cleaning, were installed on a dynamic test bench for desorption and flushing tests: demineralized water was added to the system, and desorbent was added to adjust the pH value to 10.2. The temperature was raised to 80℃, the circulation flow rate was 0.1m / s, and the circulation desorption time was 0.5 hours.

[0057] After the desorption test, the system was emptied and a flushing test was conducted: the system was replenished with demineralized water, heated to 30°C, and circulated at a flow rate of 0.1 m / s for 1 hour. Then, the water sample from the system was analyzed to measure its TOC (Total Organic Carbon, which directly reflects the amount of adsorbed organic corrosion inhibitor). Simultaneously, a comparative test (the desorption and flushing test conditions were the same as the above tests, except that no desorbent was added) and a blank test (no desorption test, only a flushing test) were performed.

[0058] The desorbent consists of 22% by mass of alkalizing agent, 0.2% by mass of solubilizer and 77.8% by mass of deionized water. The alkalizing agent consists of 55% ammonia and 45% hydrazine, and the solubilizer is an alkanolamide type solubilizer.

[0059] Table 3. Water quality conditions in Example 3, blank test, and comparative test.

[0060] Test Name TOC / (mg / L) blank test 120.0 Comparative test 119.5 Example 2 8.5

[0061] By comparison, it can be seen that the TOC content in Example 3 of the present invention is significantly lower than that in the comparative example, and the amount of adsorbed organic corrosion inhibitor is extremely low, at 8.5 mg / L. Therefore, Example 3 can promote the desorption of corrosion inhibitor.

[0062] Example 4:

[0063] The water-cooled wall tubes of a power plant, after chemical cleaning, were installed on a dynamic test bench for desorption and flushing tests: demineralized water was added to the system, and desorbent was added to adjust the pH value to 10.4. The temperature was raised to 85℃, the circulation flow rate was 0.6m / s, and the circulation desorption time was 0.5 hours.

[0064] After the desorption test, the system was emptied and a flushing test was conducted: the system was replenished with demineralized water, heated to 35°C, and circulated at a flow rate of 0.6 m / s for 0.5 hours. Then, a water quality analysis was performed on the water sample from the system, measuring its TOC (Total Organic Carbon, which directly reflects the amount of adsorbed organic corrosion inhibitor). Simultaneously, a comparative test (where the desorption and flushing test conditions were the same as the above tests, except no desorbent was added) and a blank test (where only the flushing test was performed, without the desorption test) were conducted.

[0065] The desorbent consists of 23% by mass of alkalizing agent, 0.3% of solubilizer and 76.7% of demineralized water, wherein the alkalizing agent consists of 70% ammonia and 30% hydrazine, and the solubilizer is a polyoxyethylene type solubilizer.

[0066] Table 4. Water quality conditions of Example 4, blank test, and comparative test.

[0067]

[0068]

[0069] By comparison, it can be seen that the TOC content of Example 4 of the present invention is significantly lower than that of the comparative example, and the amount of adsorbed organic corrosion inhibitor is extremely low, at 7.9 mg / L. Therefore, Example 4 can promote the desorption of corrosion inhibitor.

[0070] Example 5:

[0071] The superheater tubes of a power plant, after chemical cleaning, were installed on a dynamic test bench for desorption and flushing tests: demineralized water was added to the system, and desorbent was added to adjust the pH value to 10.5. The temperature was raised to 96℃, the circulation flow rate was 0.6m / s, and the circulation desorption time was 0.8 hours.

[0072] After the desorption test, the system was emptied and a flushing test was conducted: the system was replenished with demineralized water, heated to 26°C, and circulated at a flow rate of 0.6 m / s for 1 hour. Then, the water sample from the system was analyzed to measure its TOC (Total Organic Carbon, which directly reflects the amount of adsorbed organic corrosion inhibitor). Simultaneously, a comparative test (the desorption and flushing test conditions were the same as the above tests, except no desorbent was added) and a blank test (no desorption test, only a flushing test) were performed.

[0073] The desorbent consists of 18% by mass of alkalizing agent, 0.8% by mass of solubilizer and 81.2% by mass of deionized water. The alkalizing agent consists of 60% ammonia and 40% hydrazine, and the solubilizer is a polyether type solubilizer.

[0074] Table 5. Water quality conditions of Example 5, blank test, and comparative test.

[0075] Test Name TOC / (mg / L) blank test 100.2 Comparative test 95.6 Example 2 6.5

[0076] By comparison, it can be seen that the TOC content of Example 5 of the present invention is significantly lower than that of the comparative example, and the amount of adsorbed organic corrosion inhibitor is extremely low, at 6.5 mg / L. Therefore, Example 5 can promote the desorption of corrosion inhibitor.

[0077] Example 6:

[0078] The water-cooled wall tubes of a power plant, after chemical cleaning, were installed on a dynamic test bench for desorption and flushing tests: demineralized water was added to the system, and desorbent was added to adjust the pH value to 10.5. The temperature was raised to 90℃, the circulation flow rate was 0.5m / s, and the circulation desorption time was 1 hour.

[0079] After the desorption test, the system was emptied and a flushing test was performed: the system was replenished with demineralized water and heated to 29°C.

[0080] The circulation flow rate was 0.5 m / s. After 1 hour of circulation, the water sample in the system was analyzed to measure its TOC (total organic carbon, which directly reflects the amount of adsorbed organic corrosion inhibitor). At the same time, a comparative test (except that no desorbent was added, the desorption test and rinsing test conditions were the same as the above test) and a blank test (no desorption test was performed, only the rinsing test was performed) were conducted.

[0081] The desorbent consists of 15% by mass of alkalizing agent, 0.3% of solubilizer and 84.7% of demineralized water, wherein the alkalizing agent consists of 69% ammonia and 31% hydrazine, and the solubilizer is a polyol type solubilizer.

[0082] Table 6. Water quality conditions of Example 6, blank test, and comparative test.

[0083] Test Name TOC / (mg / L) blank test 116.2 Comparative test 100.6 Example 2 7.8

[0084] By comparison, it can be seen that the TOC content of Example 6 of the present invention is significantly lower than that of the comparative example, and the amount of adsorbed organic corrosion inhibitor is extremely low, at 7.8 mg / L. Therefore, Example 6 can promote the desorption of corrosion inhibitor.

[0085] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute included by “may” is optional.

[0086] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of the word "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0087] Many embodiments and applications beyond the examples provided will be apparent to those skilled in the art upon reading the foregoing description. Therefore, the scope of this teaching should not be determined by reference to the foregoing description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A method of using a chemical cleaning corrosion inhibitor desorbent, characterized by, The chemical cleaning corrosion inhibitor desorption agent comprises, in percentage by mass, 20-25% of an alkalizing agent, 0.1-0.3% of a solubilizer and the rest of desalted water; The alkalizing agent comprises one or both of ammonia and hydrazine; The solubilizer comprises one or more of polyoxyethylene type, polyhydric alcohol type, polyether type and alkanolamide type; The use method comprises: After chemical cleaning of the power plant, water flushing is performed, the desorption agent is added, the desorption of the corrosion inhibitor is promoted under the action of the desorption agent, and the corrosion inhibitor is taken out of the system with the water flushing.

2. The method of use of claim 1, wherein, The solubilizer has a hydrophilic-lipophilic balance (HLB) greater than 15.

3. The use method according to claim 1, characterized in that, Before the desorption agent is added, the total iron content in the system is not more than 300 mg / L.

4. The use method according to claim 1, characterized in that, The amount of the desorption agent added needs to ensure that the pH value of the solution in the system is not less than 10.

0.

5. The use method according to claim 1, characterized in that, The temperature at which the desorption agent is added is 80-95 DEG C, the circulating flow rate is 0.1-1.0 m / s, and the time is 0.5-2 hours.

6. The use method according to claim 1, characterized in that, Further comprising: Water quality analysis is performed on the water sample in the system, and the TOC of the water sample in the system is measured.

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