Chemical cleaning method for hydroxyapatite scaling substances of power station boiler

Abstract

The invention discloses a power station boiler hydroxyapatite scaling substance chemical cleaning method, and belongs to the technical field of power station thermal equipment chemical cleaning, and the method comprises the following steps: preparing a cleaning medium containing an organic chelating agent, a penetrant, a corrosion inhibitor and demineralized water, adjusting the pH value, heating, adding a cleaning auxiliary agent, injecting into a boiler system, carrying out circulation or immersion cleaning, and flushing. And finally, the boiler system is restored to the normal working state, and cleaning is completed. The chemical cleaning method comprises the following steps: selecting a cleaning medium aiming at hydroxyapatite scaling substances, controlling the medium concentration, the pH value and the cleaning temperature, and adding a cleaning assistant in the cleaning process. The cleaning method is simple, reliable and easy to implement, and the problem that hydroxyapatite scaling substances of the power station boiler are difficult to effectively remove in a traditional chemical cleaning method is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical cleaning of thermal equipment in power plants, and in particular relates to a chemical cleaning method for hydroxyapatite scaling of power plant boilers. Background Art

[0002] In the energy industry, power plant boilers are core equipment for power generation, and their operating efficiency and safety are directly related to the stability and economy of power supply. With the continuous growth of global energy demand and increasingly stringent environmental protection requirements, improving the energy efficiency of power plant boilers and reducing pollutant emissions have become important issues in the power industry. Low-parameter power plant boilers, as a key component of many power plants, are relatively mature in design and operation, but the water quality control problems they face during long-term operation cannot be ignored. The quality of water directly affects the cleanliness of the boiler heating surface and the heat exchange efficiency, which in turn affects the operating efficiency and cost of the entire power plant.

[0003] In view of the water quality control problem and the scaling phenomenon caused by it during the operation of low-parameter power station boilers, the traditional chemical cleaning method uses specific chemical agents, such as acids, alkalis or chelating agents, to dissolve or peel off the scale on the boiler heating surface, thereby achieving the purpose of cleaning. In particular, for the common iron oxide scaling on the heating surface, the traditional chemical cleaning method has shown a good removal effect. However, with the complexity of boiler operating conditions and the diversification of water quality problems, the cleaning effect of traditional processes is greatly reduced when facing certain specific types of scaling, such as hydroxyapatite. Although traditional chemical cleaning methods have played an important role in the maintenance of low-parameter power station boilers, their limitations in dealing with hydroxyapatite scaling are becoming increasingly prominent. Hydroxyapatite is a hard scaling that is easily formed on the bottom layer of the boiler heating surface. Its chemical properties are stable and it is difficult to effectively remove it by conventional chemical cleaning methods. This not only affects the heat transfer efficiency of the boiler heating surface, resulting in a decrease in boiler efficiency, but may also cause safety problems such as overheating and corrosion of the heating surface tube wall, seriously affecting the economic and safety of power station boiler operation.

[0004] In view of the problem that hydroxyapatite scaling in power station boilers is difficult to be effectively removed by traditional chemical cleaning methods, it is urgent to find a new chemical cleaning method that can effectively remove hydroxyapatite scaling, which has become a key issue that needs to be urgently solved in the current low-parameter power station boiler chemical cleaning technology. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a chemical cleaning method for hydroxyapatite scaling of power station boilers to solve the technical problem that hydroxyapatite scaling of power station boilers is difficult to be effectively removed in traditional chemical cleaning methods.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The invention discloses a chemical cleaning method for hydroxyapatite scale of a power station boiler, comprising: preparing a cleaning medium containing an organic chelating agent, a penetrant, a corrosion inhibitor and deionized water, adjusting the pH value and heating, adding a cleaning aid, injecting the medium into a boiler system, circulating or soaking the medium for cleaning, flushing the medium, checking the cleaning effect, and finally restoring the boiler system to a normal working state to complete the cleaning.

[0007] Preferably, the mass percentages of the organic chelating agent, the penetrant, the corrosion inhibitor and the cleaning aid are (1%~10%): (3%~5%): (0.1%~0.3%): (0.1%~0.5%).

[0008] Preferably, the organic chelating agent is ethylenediaminetetraacetic acid, nitrilotriacetic acid, sodium gluconate or a polycarboxylic acid chelating agent.

[0009] Preferably, the penetrant is sodium dodecyl sulfate, polyethylene glycol octylphenyl ether or an alcoholamine penetrant.

[0010] Preferably, the corrosion inhibitor is benzotriazole, mercaptobenzothiazole or thiourea and its derivatives.

[0011] Preferably, the cleaning aid is a surfactant, a dispersant, a chelating enhancer or a pH adjuster.

[0012] Preferably, the pH value of the cleaning medium is 4.5-6.5.

[0013] Preferably, the heating temperature is 80-120°C.

[0014] Preferably, the circulation or immersion cleaning time is 4 to 24 hours.

[0015] Preferably, the cleaning effect is checked by comparing the residual scale and heat exchange efficiency of the heating surface before and after cleaning.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a chemical cleaning method for hydroxyapatite scale deposits in power station boilers. A cleaning medium containing an organic chelating agent, a penetrant, a corrosion inhibitor and deionized water is prepared. This cleaning medium combination can effectively clean hydroxyapatite scale deposits. The organic chelating agent can form a stable chelate with metal ions in the scale, which is helpful for decomposing the scale; the penetrant can improve the penetration ability of the cleaning medium and make the cleaning more thorough; the corrosion inhibitor protects the metal surface of the boiler from corrosion; and the deionized water avoids the interference of ions in the water on the cleaning process. Adjusting the pH value to a suitable range can enhance the cleaning effect of the cleaning medium and avoid corrosion of the boiler material. Heating can accelerate the chemical reaction and improve the cleaning efficiency. The addition of a cleaning aid can further enhance the cleaning effect, and circulating cleaning can ensure that the cleaning medium fully contacts and dissolves the scale, while immersion cleaning gives the cleaning medium enough time to react with the scale. The rinsing step can remove the residual cleaning medium and scale fragments, so as to prepare for subsequent inspection and boiler resumption of operation. By checking the cleaning effect, the effectiveness of the cleaning process can be ensured. Comparing the residual amount of scale and heat exchange efficiency on the heating surface before and after cleaning is an intuitive and effective evaluation method, which helps to promptly discover and deal with areas that have not been cleaned thoroughly. After completing the cleaning and confirming the cleaning effect, restoring the boiler system to a normal working state is a key step to ensure safe and efficient operation of the boiler. This includes checking the integrity of various components of the boiler, adjusting operating parameters, etc., to ensure that the boiler can be put into operation stably and safely. The chemical cleaning method for hydroxyapatite scaling of power station boilers disclosed in the present invention can effectively clean and remove hydroxyapatite scaling on the heating surface of low-parameter power station boilers; ensure the chemical cleaning effect of the heating surface of low-parameter power station boilers, ensure the cleanliness of the heating surface, and improve the quality of chemical cleaning; improve the heat exchange efficiency of the heating surface, and improve the economic efficiency of power station boiler operation; the cleaning method is simple, reliable and easy to implement, and can be well applied to engineering practice.

[0017] Furthermore, the selection of the mass percentage of organic chelating agents, penetrants, corrosion inhibitors and cleaning aids is based on the optimization results in experiments and practical applications, ensuring that each component in the cleaning solution can play an effective role without causing waste or side effects due to excessive concentration. Organic chelating agents can form stable chelates with metal ions in scales, which helps dissolve scales; penetrants can improve the penetration of cleaning solutions into scale layers; corrosion inhibitors can protect metal surfaces from corrosion; and cleaning aids can enhance cleaning effects. Reasonable proportions make the entire cleaning process more efficient and economical.

[0018] Furthermore, the organic chelating agent is ethylenediaminetetraacetic acid, nitrilotriacetic acid, sodium gluconate or a polycarboxylic acid chelating agent. These organic chelating agents have good chelating ability and can form stable chelates with metal ions in hydroxyapatite, thereby effectively dissolving scale. At the same time, they have good stability in aqueous solution and are not easy to decompose, thereby ensuring the stability of the cleaning effect.

[0019] Furthermore, the penetrant is sodium dodecyl sulfate, polyethylene glycol octylphenyl ether or alcohol amine penetrant. These penetrants can significantly reduce the surface tension of the cleaning liquid, improve its wettability and permeability to the scale layer, so that the cleaning liquid can penetrate deeper into the scale layer, fully contact and react with the scale, thereby improving the cleaning efficiency.

[0020] Furthermore, the corrosion inhibitor is benzotriazole, mercaptobenzothiazole or thiourea and its derivatives. These corrosion inhibitors can form a protective film on the metal surface, effectively preventing the corrosive substances in the cleaning solution from corroding the metal surface, thereby protecting the boiler heating surface from damage. At the same time, they can also inhibit the re-deposition of scale to a certain extent.

[0021] Furthermore, the cleaning aid is a surfactant, a dispersant, a chelating enhancer or a pH adjuster. These cleaning aids can further enhance the cleaning ability of the cleaning solution. The surfactant can improve the wettability and dispersibility of the cleaning solution; the dispersant can prevent the scale from re-aggregating during the cleaning process; the chelating enhancer can improve the chelating efficiency of the organic chelating agent; and the pH adjuster can ensure that the cleaning solution works within the optimal pH range, thereby improving the cleaning effect.

[0022] Furthermore, the pH value of the cleaning medium is 4.5-6.5. Within this pH range, the cleaning fluid can effectively dissolve hydroxyapatite scaling without causing corrosion to the boiler heating surface. At the same time, the appropriate pH value can also improve the stability and cleaning efficiency of the cleaning fluid.

[0023] Furthermore, the heating temperature is 80~120℃. Within this temperature range, the reaction activity of the cleaning liquid is higher and the scale can be dissolved faster. At the same time, heating can also promote the penetration and diffusion of the cleaning liquid inside the scale layer, thereby improving the cleaning efficiency. However, too high a temperature may cause certain components in the cleaning liquid to decompose or volatilize, so it needs to be controlled within an appropriate range.

[0024] Furthermore, the circulation or immersion cleaning time is 4 to 24 hours. This period of time can ensure that the cleaning liquid fully reacts with the scale and dissolves the scale, but will not cause excessive consumption of the effective ingredients in the cleaning liquid or produce unnecessary side effects due to too long a time. At the same time, a reasonable cleaning time can also improve the economy and efficiency of the cleaning process.

[0025] Furthermore, the cleaning effect can be checked by comparing the residual scale and heat exchange efficiency of the heating surface before and after cleaning. It can directly reflect the cleaning effect. By comparing the residual scale and heat exchange efficiency before and after cleaning, the effectiveness and feasibility of the cleaning method can be accurately evaluated. At the same time, this can also provide a strong reference and basis for subsequent cleaning work. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the solution of the present invention, the following will be described clearly and completely in conjunction with the technical solution in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] The present invention is described in further detail below in conjunction with embodiments: The traditional cleaning method in power station boilers mainly includes the following steps: 1. Water flushing: remove mechanical impurities and loose dirt inside the boiler, and check whether the cleaning system has leaks. Use clean water at a flow rate greater than 0.6m / s to flush the boiler until the water is clear and free of mechanical impurities. This step is especially important for newly built equipment and equipment with a lot of mechanical impurities.

[0029] 2. Alkali washing (or alkali boiling); remove oil and rust to prepare for the subsequent pickling step. Use alkaline solution (such as sodium hydroxide and trisodium phosphate) for cleaning. The temperature of the alkali solution should not be lower than 90°C, the flow rate should be greater than 0.3m / s, and the circulation time should be 8~24h. After the alkali washing, rinse with brine or softened water until the pH value of the water is less than 8 and the water is clear without fine particles.

[0030] 3. Pickling: remove the scale and other stubborn dirt inside the boiler. Heat the prepared acid solution (such as hydrochloric acid, citric acid, hydrofluoric acid, etc.) to the required temperature and clean according to the pickling procedure. During the pickling process, the acid concentration and iron content need to be measured regularly, and acid and corrosion inhibitors should be added when necessary. After the pickling is completed, rinse with deionized water until the pH value of the drainage is 5~6, the iron content is less than 20~50mg / L, and the drainage is clear.

[0031] 4. Rinse: Remove the acid solution and secondary rust remaining inside the boiler after pickling. Use dilute citric acid solution for rinsing, with the pH value controlled between 3.5 and 4.0, the temperature at about 40°C, and the time for 2 hours. The total iron concentration in the rinsing liquid should be controlled within a certain range.

[0032] 5. Passivation: Generate a protective film on the metal surface to prevent oxidation corrosion of boiler pipes. Use hydrazine solution, sodium nitrite solution or sodium phosphate solution (or a mixture of sodium phosphate and sodium hydroxide) for passivation. The pH value, temperature and circulation time of the solution need to be controlled during the passivation process.

[0033] 6. Water flushing and ammonia flushing: remove the residual solution from the passivation process to make the boiler interior clean. First flush with clean water, then flush with ammonia. After flushing, store it full of water.

[0034] 7. Waste liquid treatment; Environmentally friendly treatment of waste liquid generated during cleaning to prevent environmental pollution. According to the nature of the waste liquid and environmental protection requirements, select appropriate treatment methods for treatment.

[0035] The invention discloses a chemical cleaning method for hydroxyapatite scale of a power station boiler. The method adopts 1% to 10% organic chelating agent, 3% to 5% penetrant, 0.1% to 0.3% corrosion inhibitor and deionized water as main cleaning medium, adjusts the initial pH value of the cleaning medium to 4.5 to 6.5, the cleaning temperature to 80 to 120°C, adds 0.1% to 0.5% cleaning aid, and the cleaning time to 4 to 24 hours. A small amount of hydroxyapatite scale in a power station boiler can be effectively cleaned and removed. After the implementation stage of the traditional chemical cleaning method, a chemical cleaning method for hydroxyapatite scale of a power station boiler is added. The method can effectively clean and remove hydroxyapatite scale that cannot be removed by the traditional cleaning method in the power station boiler. The method solves the problem that the chemical cleaning of the heating surface of a low-parameter power station boiler is difficult and the residual scale is high after cleaning, and improves the chemical cleaning quality of the heating surface of the low-parameter power station boiler.

[0036] Organic chelating agents are ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), sodium gluconate or polycarboxylic acid chelating agents; ethylenediaminetetraacetic acid (EDTA) has a strong chelating ability and can effectively bind to metal ions to prevent them from forming insoluble precipitation, thereby enhancing the cleaning effect. Nitrilotriacetic acid (NTA) is an environmentally friendly chelating agent with excellent solubility for hydroxyapatite scale, and has good biodegradability and reduces environmental impact. Sodium gluconate, as a natural chelating agent, can not only effectively chelate metal ions, but also enhance the stability of the cleaning medium and reduce the impact on the environment. Polycarboxylic acid chelating agents, such as polyacrylic acid (PAA), have good dispersibility and chelating properties, and can effectively prevent scale from re-deposition. Further screening and optimization of the types and concentrations of organic chelating agents, using environmentally friendly organic chelating agents with stronger chelating ability to reduce the impact on the environment while improving cleaning efficiency. Significantly improve cleaning efficiency and reduce cleaning time; protect boiler materials and reduce corrosion risks; the use of environmentally friendly chelating agents helps to reduce environmental burden.

[0037] The penetrant is sodium dodecyl sulfate (SDS), polyethylene glycol octyl phenyl ether (OP) or alcohol amine penetrant; sodium dodecyl sulfate (SDS) is a commonly used surfactant with good wettability and permeability, which helps to evenly distribute the cleaning medium. Polyethylene glycol octyl phenyl ether (OP) is a non-ionic surfactant with excellent penetration and dispersion effects on hydroxyapatite scale. Alcohol amine penetrants, such as triethanolamine, not only have good permeability, but also can adjust the pH value of the cleaning medium to a certain extent. Selecting a penetrant with higher permeability and wettability can help the cleaning medium better penetrate into the scale layer and accelerate the dissolution and peeling of scale. Enhance the penetration ability of the cleaning medium into the scale layer and accelerate the dissolution of scale; improve the wettability of the cleaning medium to ensure uniform cleaning; help reduce the use of cleaning additives and reduce costs.

[0038] The corrosion inhibitors are benzotriazole (BTA), thiourea and its derivatives or mercaptobenzothiazole (MBT); benzotriazole (BTA) has excellent corrosion inhibition effect on various metal materials, especially in acidic environments. Thiourea and its derivatives, such as N,N'-dimethylthiourea, can effectively inhibit metal corrosion without affecting the cleaning efficiency. Mercaptobenzothiazole (MBT) is a highly efficient, low-toxic corrosion inhibitor suitable for a variety of metal materials. Use more efficient corrosion inhibitors to reduce the risk of corrosion to boiler materials during the cleaning process, especially for sensitive materials that may be used in low-parameter boilers. Significantly reduce the risk of corrosion to boiler materials during the cleaning process; extend the service life of the boiler and reduce maintenance costs; improve the safety of the cleaning process and reduce the risk of accidents.

[0039] High-purity demineralized water is prepared by reverse osmosis (RO) or electrodialysis (ED) technology to ensure that the ion content in the water is extremely low. The demineralized water is pretreated, such as filtration and deoxygenation, to remove impurities such as suspended matter, organic matter and dissolved oxygen. According to the composition of the scale and the cleaning requirements, specific cleaning additives such as surfactants and dispersants are added to further enhance the cleaning effect. Provide a stable cleaning medium foundation to ensure the consistency of the cleaning effect; reduce the interference of impurities in the water on the cleaning process and improve the cleaning efficiency; reduce the risk of residues inside the boiler after cleaning and ensure the cleanliness of the boiler.

[0040] Cleaning aids include: surfactants (such as sodium dodecyl sulfate); dispersants (such as sodium polyacrylate); chelating enhancers (such as sodium citrate); pH adjusters (such as ammonia, acetic acid). Surfactants can significantly reduce the surface tension of the cleaning medium, improve wettability and permeability, and enhance the cleaning effect. Dispersants help disperse and suspend dissolved scale particles to prevent their redeposition and improve cleaning efficiency. Chelating enhancers can enhance the chelating ability of the cleaning medium and help dissolve and remove more stubborn hydroxyapatite scale. pH adjusters can accurately adjust the pH value of the cleaning medium to the optimal cleaning range, improve cleaning efficiency and reduce the risk of corrosion to boiler materials.

[0041] By precisely controlling the pH value of the cleaning medium to keep it within the optimal range (such as 4.5~6.5), the cleaning efficiency can be maximized while reducing potential corrosion to boiler materials.

[0042] Optimize the cleaning temperature range (80~120℃) and select the most suitable cleaning temperature according to the scale characteristics and thermal stability of the boiler material to improve the cleaning speed and efficiency.

[0043] According to the thickness of scale and cleaning effect, the cleaning time (4~24h) can be flexibly adjusted to ensure thorough and not excessive cleaning.

[0044] During the cleaning process, online monitoring technology (such as pH value, temperature, conductivity, etc.) is used to monitor the status of the cleaning medium in real time so that the cleaning parameters can be adjusted in time.

[0045] Before and after cleaning, the cleaning effect is scientifically evaluated by comparing indicators such as the amount of scale residue on the heating surface and the heat exchange efficiency, providing a basis for the subsequent optimization of the cleaning plan.

[0046] Example 1 A chemical cleaning method for hydroxyapatite scaling of a power station boiler comprises the following steps: Prepare a cleaning medium containing 1% organic chelating agent ethylenediaminetetraacetic acid, 3% penetrant sodium dodecyl sulfate, 0.1% corrosion inhibitor benzotriazole and deionized water, adjust the pH value to 4.5 and heat to 80°C, add 0.1% cleaning aid surfactant sodium dodecyl sulfate, inject it into the boiler system, circulate for 4 hours, flush it, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

[0047] Example 2 A chemical cleaning method for hydroxyapatite scaling of a power station boiler comprises the following steps: Prepare a cleaning medium containing 3% organic chelating agent nitrilotriacetic acid, 3.5% penetrant polyethylene glycol octylphenyl ether, 0.15% corrosion inhibitor mercaptobenzothiazole and deionized water, adjust the pH value to 4.7 and heat to 90°C, add 0.2% cleaning aid dispersant sodium polyacrylate, inject it into the boiler system, soak and clean for 8 hours, rinse, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

[0048] Example 3 A chemical cleaning method for hydroxyapatite scaling of a power station boiler comprises the following steps: Prepare a cleaning medium containing 3% organic chelating agent sodium gluconate, 3.5% alcohol amine penetrant, 0.15% corrosion inhibitor thiourea and desalted water, adjust the pH value to 5.0 and heat to 100°C, add 0.2% cleaning aid chelating enhancer sodium citrate, inject it into the boiler system, circulate for 12 hours, rinse, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

[0049] Example 4 A chemical cleaning method for hydroxyapatite scaling of a power station boiler comprises the following steps: Prepare a cleaning medium containing 5% organic chelating agent polycarboxylic acid chelating agent, 4.5% penetrant, 0.25% corrosion inhibitor and desalted water, adjust the pH value to 5.5 and heat to 110°C, add 0.4% cleaning aid pH adjuster ammonia water, inject it into the boiler system, soak and clean for 18 hours, rinse, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

[0050] Example 5 A chemical cleaning method for hydroxyapatite scaling of a power station boiler comprises the following steps: Prepare a cleaning medium containing 10% organic chelating agent ethylenediaminetetraacetic acid, 5% penetrant polyethylene glycol octylphenyl ether, 0.3% corrosion inhibitor thiourea and deionized water, adjust the pH value to 5.8 and heat to 120°C, add 0.5% cleaning aid pH adjuster acetic acid, inject it into the boiler system, circulate for 24 hours, rinse, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

[0051] Example 6 A chemical cleaning method for hydroxyapatite scaling of a power station boiler comprises the following steps: Prepare a cleaning medium containing 2% organic chelating agent sodium gluconate, 3% penetrant sodium dodecyl sulfate, 0.1% corrosion inhibitor mercaptobenzothiazole and deionized water, adjust the pH value to 6.5 and heat to 80°C, add 0.1% cleaning aid surfactant sodium dodecyl sulfate, inject it into the boiler system, soak and clean for 4 hours, rinse, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

[0052] The invention discloses a chemical cleaning method for hydroxyapatite scaling of power station boilers, which includes the selection of a cleaning medium for hydroxyapatite scaling, the control of medium concentration, pH value, and cleaning temperature, and the addition of a cleaning aid during the cleaning process. The cleaning method of the invention is simple, reliable, and easy to implement, and solves the problem that hydroxyapatite scaling of power station boilers is difficult to effectively remove in traditional chemical cleaning methods.

[0053] For the heating surface of the power station boiler, especially the heating surface of the low pressure parameter boiler, the hydroxyapatite scaling can be effectively removed, which can ensure the cleanliness of the heating surface of the power station boiler, improve the heat exchange efficiency of the heating surface, and improve the economic efficiency of the operation of the power station boiler. Compared with the prior art, the present invention has the following advantages: 1) It can effectively clean and remove hydroxyapatite scaling on the heating surface of low-parameter power station boilers; 2) Ensure the chemical cleaning effect of the heating surface of low-parameter power station boilers, ensure the cleanliness of the heating surface, and improve the quality of chemical cleaning; 3) Improve the heat transfer efficiency of the heating surface and improve the economic efficiency of power plant boiler operation; 4) The cleaning method is simple, reliable and easy to implement, and can be well applied in engineering practice.

[0054] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A chemical cleaning method for hydroxyapatite scaling in power station boilers, It is characterized in that include: Prepare a cleaning medium containing organic chelating agent, penetrant, corrosion inhibitor and desalted water, adjust the pH value and heat it, add cleaning aids, inject it into the boiler system, circulate or soak it for cleaning, rinse it, check the cleaning effect, and finally restore the boiler system to normal working condition to complete the cleaning.

2. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The mass percentages of the organic chelating agent, penetrant, corrosion inhibitor and cleaning aid are (1%~10%): (3%~5%): (0.1%~0.3%): (0.1%~0.5%).

3. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The organic chelating agent is ethylenediaminetetraacetic acid, nitrilotriacetic acid, sodium gluconate or a polycarboxylic acid chelating agent.

4. The chemical cleaning method for hydroxyapatite scale of a power station boiler according to claim 1, It is characterized in that The penetrant is sodium dodecyl sulfate, polyethylene glycol octylphenyl ether or alcoholamine penetrant.

5. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The corrosion inhibitor is benzotriazole, mercaptobenzothiazole or thiourea and derivatives thereof.

6. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The cleaning aid is a surfactant, a dispersant, a chelating enhancer or a pH adjuster.

7. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The pH value of the cleaning medium is 4.5-6.

5.

8. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The heating temperature is 80-120°C.

9. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The circulation or immersion cleaning time is 4 to 24 hours.

10. The chemical cleaning method for hydroxyapatite scale of power station boiler according to claim 1, It is characterized in that The cleaning effect can be checked by comparing the residual scale and heat exchange efficiency on the heating surface before and after cleaning.