Chemical cleaning agent based on polyamide and use process thereof
Through the use of polyamide-based chemical cleaning agents, non-ionic surfactant modification and multi-porous structure design, combined with temperature gradient control and ultrasonic assistance, the problems of poor penetration and emulsification effects of existing cleaning agents were solved, and efficient cleaning of octadecylamine anti-corrosion materials was achieved.
Patent Information
- Application Number
- CN202510774790.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-11
- Publication Date
- 2025-09-16
AI Technical Summary
Existing chemical cleaning agents have poor penetration and emulsification effects on octadecylamine anti-corrosion materials, resulting in unsatisfactory cleaning effects.
A polyamide-based chemical cleaning agent is used, which contains non-ionic surfactants, zwitterionic surfactants, chelating agents, defoaming agents and organic solvents. Through the modification of non-ionic surfactants and the design of multi-porous structures, combined with temperature gradient control and ultrasonic assistance, the penetration and emulsification effects of the cleaning agent are improved.
It significantly improves the cleaning effect of octadecylamine anti-corrosion materials, enhances the penetration ability and emulsification performance of the cleaning agent, effectively removes organic pollutants such as grease, oil, wax, etc., and improves cleaning efficiency.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chemical cleaning agents, and more particularly to a polyamide-based chemical cleaning agent and a use process thereof. Background Art
[0002] With the development of the power industry, unit startups and shutdowns are becoming increasingly frequent. Without effective protection during these downtimes, thermal equipment can be severely damaged, resulting in significant economic losses and major safety hazards. It's reported that 80% of iron hooks found in furnace tubes are caused by oxygen corrosion during downtime. Corrosion accounts for 40-50% of thermal equipment accidents, and unit efficiency losses due to corrosion are estimated to be 2% annually. Therefore, corrosion prevention technology for thermal systems has long been a topic of research in both industry and academia.
[0003] In the 1950s, film-forming anti-corrosion materials based on octadecylamine began to be used in steam condensation reflux systems. In these systems, the factors affecting corrosion are usually oxygen entering the pipeline and carbon dioxide generated by the decomposition of salts in the boiler water and feed water. In order to effectively protect the metal surface and prevent it from contact with oxygen and carbon dioxide, an octadecylamine solution with a concentration of no more than 3 mg / L is usually used. It enters the pipeline with the steam and settles on the pipe wall. In this way, octadecylamine can effectively adsorb on the clean metal surface to form a hydrophobic layer, preventing acid corrosion and oxygen corrosion in the pipeline. Experiments have shown that the degree of corrosion in thermal systems protected by octadecylamine film-forming anti-corrosion materials is reduced by 90% compared to unprotected systems.
[0004] Octadecylamine is a waxy solid at room temperature, and its dosing method is a major factor limiting its widespread application. In the late 1980s, liquid octadecylamine anti-corrosion materials began to be used for the standby protection of various types of thermal power generation units. Liquid octadecylamine anti-corrosion technology was introduced in 1993, and many domestic power research institutes and universities subsequently conducted related technical research, development, and application. Since 1997, liquid octadecylamine anti-corrosion technology has been widely used in China for the standby protection of thermal power generation units.
[0005] However, there are still some technical obstacles when using octadecylamine anti-corrosion materials for the standby protection of thermal power generating units. For example, octadecylamine anti-corrosion materials are not convenient to clean from the equipment, and existing chemical cleaning agents have insufficient penetration and emulsification effects on octadecylamine anti-corrosion materials, resulting in poor cleaning effects. Summary of the Invention
[0006] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a polyamide-based chemical cleaning agent and a process for using the same. The problem to be solved by the present invention is: how to improve the penetration and emulsification effect of the chemical cleaning agent on the octadecylamine anti-corrosion material, and improve the cleaning effect on the octadecylamine anti-corrosion material.
[0007] To achieve the above object, the present invention provides the following technical solution: a polyamide-based chemical cleaning agent, the chemical cleaning agent comprising the following raw materials in percentage by mass: 20-30% nonionic surfactant, 10-20% zwitterionic surfactant, 1-5% chelating agent, 1-3% defoaming agent, 15-25% organic solvent, and the remainder being water; The nonionic surfactant is a polyamide surfactant modified with dihydroxyethyl imidazoline.
[0008] In a preferred embodiment, the chemical cleaning agent comprises the following raw materials in percentage by mass: 23-27% nonionic surfactant, 13-17% zwitterionic surfactant, 2-4% chelating agent, 1.5-2.5% defoaming agent, 18-22% organic solvent, and the remainder is water.
[0009] In a preferred embodiment, the chemical cleaning agent comprises the following raw materials in percentage by mass: 25% nonionic surfactant, 15% zwitterionic surfactant, 3% chelating agent, 2% defoaming agent, 20% organic solvent, and the remainder is water.
[0010] In a preferred embodiment, the zwitterionic surfactant is one of oleamidopropyl betaine, erucamidopropyl betaine, and hydroxyethyl betaine; the chelating agent is cyclohexanehexol phosphate; the defoaming agent is one of Dow Corning AFE-3168, Dow Corning AFE-7610, BASF DF9010F, or Air Chemical DA745; and the organic solvent is a mixture of ethylene glycol butyl ether, isopropyl alcohol, and limonene.
[0011] In a preferred embodiment, the volume ratio of ethylene glycol butyl ether, isopropyl alcohol and limonene is 1: (0.4-0.6): (0.1-0.4).
[0012] In a preferred embodiment, the preparation method of the nonionic surfactant is: S1: dissolving m-phenylenediamine and dihydroxyethyl imidazoline in water and stirring until completely dissolved to obtain an aqueous solution; S2: immersing the porous ultrafiltration polysulfone membrane in the aqueous solution, removing it from the aqueous solution, and removing excess droplets with an air knife; S3: coating a porous ultrafiltration polysulfone membrane with a solution of trimesoyl chloride; S4: thermally cross-linking a porous ultrafiltration polysulfone membrane coated with trimesoyl chloride with polyamide to obtain a nonionic surfactant.
[0013] In a preferred embodiment, the mass percentage concentration of phenylenediamine in the S1 aqueous solution is 0.1-5wt%, the mass percentage concentration of dihydroxyethyl imidazoline in the aqueous solution is 0.1-10wt%, and the immersion time of the porous ultrafiltration polysulfone membrane in the aqueous solution in S2 is 1-5min; the temperature during thermal crosslinking in S4 is 80-160°C, and the thermal crosslinking time is 2-10min.
[0014] In a preferred embodiment, the preparation method of the chemical cleaning agent is: The raw materials are weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water are stirred and mixed uniformly at 300-600 rpm and 50-80° C. to obtain a polyamide-based chemical cleaning agent.
[0015] A process for using a polyamide-based chemical cleaning agent comprises the following steps: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 3-5 hours; Step 2: Fill the supercritical unit with superheater protection liquid and then pickle for 8-10 hours; Step 3: After pickling, rinse with water again for 3-6 hours; Step 4: using a polyamide-based chemical cleaning agent as claimed in claim 8 to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
[0016] In a preferred embodiment, the rinsing and passivation in step 4 is assisted by 40kHz, 200W ultrasonic waves, first rinsing and passivation at 40-50°C for 20-40 minutes, and then rinsing and passivation at 70-80°C for 30-60 minutes.
[0017] The technical effects and advantages of the present invention are as follows: 1. The present invention is a chemical cleaning agent based on polyamide, which adopts nonionic surfactant, zwitterionic surfactant, ethylene glycol butyl ether, isopropyl alcohol and limonene as raw materials. The nonionic surfactant is a polyamide active agent modified with dihydroxyethyl imidazoline. Polyamide itself can effectively remove organic pollutants such as grease, oil, wax, and carbon deposits as a surfactant. The present application also embeds dihydroxyethyl imidazoline in the polyamide, which can improve the hydrophilicity of the polyamide and form a multi-porous structure. The width of the water-organic miscible zone can be expanded, making it easier for the chemical cleaning agent to penetrate into the octadecylamine anti-corrosion material. The zwitterionic surfactant and the nonionic surfactant can be used in combination to improve the high interfacial activity and improve the emulsification effect of the cleaning agent. The organic solvent of the present application is a compound of ethylene glycol butyl ether, isopropyl alcohol and limonene. Ethylene glycol butyl ether has both hydrophilicity and lipophilicity and can swell the octadecylamine alkyl chain. Isopropyl alcohol can reduce viscosity and promote the penetration effect of the cleaning agent. Limonene has a strong solubility for the long-chain hydrocarbons in the octadecylamine material, destroys the octadecylamine crystallization area, and has a better cleaning effect on the octadecylamine material. 2. The chelating agent of the present invention adopts cyclohexane hexanol phosphate, which has a large complexing ability, is less dependent on pH value and temperature, and has high stability of the complex or chelate ring. In addition, when using a chemical cleaning agent to pickle and passivate the octadecylamine anti-corrosion material, temperature gradient control is adopted. First, low-temperature treatment is performed to promote the penetration of the cleaning agent, and then the temperature is increased to allow the cleaning agent to clean the glass of the octadecylamine anti-corrosion material. In addition, the emulsification and penetration efficiency can be improved with the assistance of ultrasound. DETAILED DESCRIPTION
[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.
[0019] Example 1: The present invention provides a polyamide-based chemical cleaning agent, which comprises the following raw materials in percentage by mass: 20% nonionic surfactant, 10% zwitterionic surfactant, 1% chelating agent, 1% defoaming agent, 15% organic solvent, and the remainder is water; The nonionic surfactant is a polyamide surfactant modified with dihydroxyethyl imidazoline.
[0020] In a preferred embodiment, the zwitterionic surfactant is oleamidopropyl betaine, the chelating agent is cyclohexane hexol phosphate; the defoaming agent is Dow Corning AFE-3168, and the organic solvent is a mixture of ethylene glycol butyl ether, isopropyl alcohol and limonene.
[0021] In a preferred embodiment, the volume ratio of ethylene glycol butyl ether, isopropyl alcohol and limonene is 1:0.5:0.2.
[0022] In a preferred embodiment, the preparation method of the nonionic surfactant is: S1: dissolving m-phenylenediamine and dihydroxyethyl imidazoline in water and stirring until completely dissolved to obtain an aqueous solution; S2: immersing the porous ultrafiltration polysulfone membrane in the aqueous solution, removing it from the aqueous solution, and removing excess droplets with an air knife; S3: coating a porous ultrafiltration polysulfone membrane with a solution of trimesoyl chloride; S4: thermally cross-linking a porous ultrafiltration polysulfone membrane coated with trimesoyl chloride with polyamide to obtain a nonionic surfactant.
[0023] In a preferred embodiment, the mass percentage concentration of phenylenediamine in the S1 aqueous solution is 2.5wt%, the mass percentage concentration of dihydroxyethyl imidazoline in the aqueous solution is 5wt%, the immersion time of the porous ultrafiltration polysulfone membrane in the aqueous solution in S2 is 3 minutes; the temperature during thermal crosslinking in S4 is 120°C, and the thermal crosslinking time is 6 minutes.
[0024] In a preferred embodiment, the preparation method of the chemical cleaning agent is: The raw materials were weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water were stirred and mixed at 500 rpm and 70° C. to obtain a polyamide-based chemical cleaning agent.
[0025] A process for using a polyamide-based chemical cleaning agent comprises the following steps: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 4 hours; Step 2: Fill the supercritical unit with superheater protection fluid and then pickle for 9 hours; Step 3: After pickling, rinse with water again for 5 hours; Step 4: Use the above chemical cleaning agent to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
[0026] In a preferred embodiment, the rinsing and passivation in step 4 is assisted by 40kHz, 200W ultrasonic waves, firstly rinsing and passivation at 45°C for 30 minutes, and then rinsing and passivation at 75°C for 45 minutes.
[0027] Example 2: Different from Example 1, the chemical cleaning agent includes the following raw materials in the following mass percentages: 25% nonionic surfactant, 15% zwitterionic surfactant, 3% chelating agent, 2% defoaming agent, 20% organic solvent, and the rest is water.
[0028] Example 3: Different from Example 1, the chemical cleaning agent includes the following raw materials in percentage by mass: 30% nonionic surfactant, 20% zwitterionic surfactant, 5% chelating agent, 3% defoaming agent, 25% organic solvent, and the rest is water.
[0029] Example 4: The present invention provides a polyamide-based chemical cleaning agent, which comprises the following raw materials in percentage by mass: 20% nonionic surfactant, 10% zwitterionic surfactant, 1% chelating agent, 1% defoaming agent, 15% organic solvent, and the remainder is water; The nonionic surfactant is a polyamide surfactant.
[0030] In a preferred embodiment, the zwitterionic surfactant is oleamidopropyl betaine, the chelating agent is cyclohexane hexol phosphate; the defoaming agent is Dow Corning AFE-3168, and the organic solvent is a mixture of ethylene glycol butyl ether, isopropyl alcohol and limonene.
[0031] In a preferred embodiment, the volume ratio of ethylene glycol butyl ether, isopropyl alcohol and limonene is 1:0.5:0.2.
[0032] In a preferred embodiment, the preparation method of the chemical cleaning agent is: The raw materials were weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water were stirred and mixed at 500 rpm and 70° C. to obtain a polyamide-based chemical cleaning agent.
[0033] A process for using a polyamide-based chemical cleaning agent comprises the following steps: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 4 hours; Step 2: Fill the supercritical unit with superheater protection fluid and then pickle for 9 hours; Step 3: After pickling, rinse with water again for 5 hours; Step 4: Use the above chemical cleaning agent to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
[0034] In a preferred embodiment, the rinsing and passivation in step 4 is assisted by 40kHz, 200W ultrasonic waves, firstly rinsing and passivation at 45°C for 30 minutes, and then rinsing and passivation at 75°C for 45 minutes.
[0035] Example 5: The present invention provides a polyamide-based chemical cleaning agent, which comprises the following raw materials in percentage by mass: 20% nonionic surfactant, 10% zwitterionic surfactant, 1% chelating agent, 1% defoaming agent, 15% organic solvent, and the remainder is water; The nonionic surfactant is a polyamide surfactant modified with dihydroxyethyl imidazoline.
[0036] In a preferred embodiment, the zwitterionic surfactant is oleamidopropyl betaine, the chelating agent is cyclohexane hexol phosphate; the defoaming agent is Dow Corning AFE-3168, and the organic solvent is ethylene glycol butyl ether.
[0037] In a preferred embodiment, the preparation method of the nonionic surfactant is: S1: dissolving m-phenylenediamine and dihydroxyethyl imidazoline in water and stirring until completely dissolved to obtain an aqueous solution; S2: immersing the porous ultrafiltration polysulfone membrane in the aqueous solution, removing it from the aqueous solution, and removing excess droplets with an air knife; S3: coating a porous ultrafiltration polysulfone membrane with a solution of trimesoyl chloride; S4: thermally cross-linking a porous ultrafiltration polysulfone membrane coated with trimesoyl chloride with polyamide to obtain a nonionic surfactant.
[0038] In a preferred embodiment, the mass percentage concentration of phenylenediamine in the S1 aqueous solution is 2.5wt%, the mass percentage concentration of dihydroxyethyl imidazoline in the aqueous solution is 5wt%, the immersion time of the porous ultrafiltration polysulfone membrane in the aqueous solution in S2 is 3 minutes; the temperature during thermal crosslinking in S4 is 120°C, and the thermal crosslinking time is 6 minutes.
[0039] In a preferred embodiment, the preparation method of the chemical cleaning agent is: The raw materials were weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water were stirred and mixed at 500 rpm and 70° C. to obtain a polyamide-based chemical cleaning agent.
[0040] A process for using a polyamide-based chemical cleaning agent comprises the following steps: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 4 hours; Step 2: Fill the supercritical unit with superheater protection fluid and then pickle for 9 hours; Step 3: After pickling, rinse with water again for 5 hours; Step 4: Use the above chemical cleaning agent to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
[0041] In a preferred embodiment, the rinsing and passivation in step 4 is assisted by 40kHz, 200W ultrasonic waves, firstly rinsing and passivation at 45°C for 30 minutes, and then rinsing and passivation at 75°C for 45 minutes.
[0042] Example 6: The present invention provides a polyamide-based chemical cleaning agent, which comprises the following raw materials in percentage by mass: 20% nonionic surfactant, 10% zwitterionic surfactant, 1% chelating agent, 1% defoaming agent, 15% organic solvent, and the remainder is water; The nonionic surfactant is a polyamide surfactant modified with dihydroxyethyl imidazoline.
[0043] In a preferred embodiment, the zwitterionic surfactant is oleamidopropyl betaine, the chelating agent is cyclohexane hexol phosphate; the defoaming agent is Dow Corning AFE-3168, and the organic solvent is a mixture of ethylene glycol butyl ether, isopropyl alcohol and limonene.
[0044] In a preferred embodiment, the volume ratio of ethylene glycol butyl ether, isopropyl alcohol and limonene is 1:0.5:0.2.
[0045] In a preferred embodiment, the preparation method of the nonionic surfactant is: S1: dissolving m-phenylenediamine and dihydroxyethyl imidazoline in water and stirring until completely dissolved to obtain an aqueous solution; S2: immersing the porous ultrafiltration polysulfone membrane in the aqueous solution, removing it from the aqueous solution, and removing excess droplets with an air knife; S3: coating a porous ultrafiltration polysulfone membrane with a solution of trimesoyl chloride; S4: thermally cross-linking a porous ultrafiltration polysulfone membrane coated with trimesoyl chloride with polyamide to obtain a nonionic surfactant.
[0046] In a preferred embodiment, the mass percentage concentration of phenylenediamine in the S1 aqueous solution is 2.5wt%, the mass percentage concentration of dihydroxyethyl imidazoline in the aqueous solution is 5wt%, the immersion time of the porous ultrafiltration polysulfone membrane in the aqueous solution in S2 is 3 minutes; the temperature during thermal crosslinking in S4 is 120°C, and the thermal crosslinking time is 6 minutes.
[0047] In a preferred embodiment, the preparation method of the chemical cleaning agent is: The raw materials were weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water were stirred and mixed at 500 rpm and 70° C. to obtain a polyamide-based chemical cleaning agent.
[0048] A process for using a polyamide-based chemical cleaning agent comprises the following steps: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 4 hours; Step 2: Fill the supercritical unit with superheater protection fluid and then pickle for 9 hours; Step 3: After pickling, rinse with water again for 5 hours; Step 4: Use the above chemical cleaning agent to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
[0049] In a preferred embodiment, the rinsing and passivation in step 4 is carried out at 60° C. for 1.5 hours.
[0050] Comparative Example: The present invention provides a polyamide-based chemical cleaning agent, which comprises the following raw materials in percentage by mass: 20% nonionic surfactant, 1% chelating agent, 1% defoaming agent, 15% organic solvent, and the remainder water; The nonionic surfactant is a polyamide surfactant.
[0051] In a preferred embodiment, the chelating agent is cyclohexane hexol phosphate; the defoaming agent is Dow Corning AFE-3168; and the organic solvent is ethylene glycol butyl ether.
[0052] In a preferred embodiment, the preparation method of the chemical cleaning agent is: The raw materials were weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water were stirred and mixed at 500 rpm and 70° C. to obtain a polyamide-based chemical cleaning agent.
[0053] A process for using a polyamide-based chemical cleaning agent comprises the following steps: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 4 hours; Step 2: Fill the supercritical unit with superheater protection fluid and then pickle for 9 hours; Step 3: After pickling, rinse with water again for 5 hours; Step 4: Use the above chemical cleaning agent to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
[0054] In a preferred embodiment, the rinsing and passivation in step 4 is carried out at 60° C. for 1.5 hours.
[0055] The polyamide-based chemical cleaning agents produced in Examples 1-6 were used as experimental groups 1, 2, 3, 4, 5, and 6, respectively, and the chemical cleaning agent produced in the comparative example was used as the control group. The selected chemical cleaning agents were used according to the above-mentioned process to clean the octadecylamine anti-corrosion material in the supercritical unit under the same conditions (same thickness and volume). The cleaning rate of the octadecylamine anti-corrosion material after the water rinse in step 5 was measured. The cleaning rate is the total amount of anti-corrosion material before cleaning minus the remaining amount of anti-corrosion material after cleaning, and then divided by the total amount of anti-corrosion material before cleaning.
[0056] The measurement results are shown in Table 1:
[0057] Table 1 3. As can be seen from Table 1 above, the polyamide-based chemical cleaning agent produced in this embodiment has a better cleaning effect on the octadecylamine anti-corrosion material in the supercritical unit. Example 4 uses unmodified polyamide material, and its cleaning rate is significantly reduced, while Example 5 and Example 6 use a single organic solvent and a single temperature for pickling and passivation, and their cleaning rates are slightly reduced. Therefore, the present invention uses non-ionic surfactants, zwitterionic surfactants, ethylene glycol butyl ether, isopropyl alcohol and limonene as raw materials. The non-ionic surfactant is a polyamide active agent modified with dihydroxyethyl imidazoline. Polyamide itself can effectively remove organic pollutants such as grease, oil, wax, and carbon deposits as a surfactant. The present application also embeds dihydroxyethyl imidazoline in polyamide, which can improve the hydrophilicity of polyamide and form a multi-porous structure. The width of the water-organic miscible zone can be expanded, making it easier for the chemical cleaning agent to penetrate into the octadecylamine anti-corrosion material. The zwitterionic surfactant and non-ionic surfactant can be used in combination to improve high interfacial activity. The organic solvent of the present application is a compound of ethylene glycol butyl ether, isopropyl alcohol and limonene. Ethylene glycol butyl ether has both hydrophilicity and lipophilicity and can swell the alkyl chain of octadecylamine. Isopropyl alcohol can reduce the viscosity and promote the penetration effect of the cleaning agent. Limonene has a strong solubility for the long-chain hydrocarbons in the octadecylamine material, destroys the crystalline region of octadecylamine, and has a better cleaning effect on the octadecylamine material. When using a chemical cleaning agent to pickle and passivate the octadecylamine anti-corrosion material, temperature gradient control is adopted. The low-temperature treatment is first carried out to promote the penetration of the cleaning agent, and then the temperature is increased to allow the cleaning agent to clean the glass of the octadecylamine anti-corrosion material, and the emulsification and penetration efficiency can be improved with the assistance of ultrasound.
[0058] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A polyamide-based chemical cleaning agent, characterized in that: The chemical cleaning agent comprises the following raw materials in percentage by mass: 20-30% nonionic surfactant, 10-20% zwitterionic surfactant, 1-5% chelating agent, 1-3% defoaming agent, 15-25% organic solvent, and the remainder is water; The nonionic surfactant is a polyamide surfactant modified with dihydroxyethyl imidazoline.
2. A polyamide-based chemical cleaning agent according to claim 1, characterized in that: The chemical cleaning agent comprises the following raw materials in percentage by mass: 23-27% nonionic surfactant, 13-17% zwitterionic surfactant, 2-4% chelating agent, 1.5-2.5% defoaming agent, 18-22% organic solvent, and the remainder is water.
3. The polyamide-based chemical cleaning agent according to claim 1, characterized in that: The chemical cleaning agent comprises the following raw materials in percentage by mass: 25% nonionic surfactant, 15% zwitterionic surfactant, 3% chelating agent, 2% defoaming agent, 20% organic solvent, and the remainder is water.
4. The polyamide-based chemical cleaning agent according to claim 1, characterized in that: The zwitterionic surfactant is one of oleamidopropyl betaine, erucamidopropyl betaine, and hydroxyethyl betaine; the chelating agent is cyclohexanehexol phosphate; the defoaming agent is one of Dow Corning AFE-3168, Dow Corning AFE-7610, BASF DF9010F, or Air Chemical DA745; and the organic solvent is a mixture of ethylene glycol butyl ether, isopropyl alcohol, and limonene.
5. The polyamide-based chemical cleaning agent according to claim 4, characterized in that: The volume ratio of the ethylene glycol butyl ether, isopropyl alcohol and limonene is 1: (0.4-0.6): (0.1-0.4).
6. The polyamide-based chemical cleaning agent according to claim 1, characterized in that: The preparation method of the nonionic surfactant is: S1: dissolving m-phenylenediamine and dihydroxyethyl imidazoline in water and stirring until completely dissolved to obtain an aqueous solution; S2: immersing the porous ultrafiltration polysulfone membrane in the aqueous solution, removing it from the aqueous solution, and removing excess droplets with an air knife; S3: coating a porous ultrafiltration polysulfone membrane with a solution of trimesoyl chloride; S4: thermally cross-linking a porous ultrafiltration polysulfone membrane coated with trimesoyl chloride with polyamide to obtain a nonionic surfactant.
7. A polyamide-based chemical cleaning agent according to claim 6, characterized in that: The mass percentage concentration of phenylenediamine in the S1 aqueous solution is 0.1-5wt%, the mass percentage concentration of dihydroxyethyl imidazoline in the aqueous solution is 0.1-10wt%, and the immersion time of the porous ultrafiltration polysulfone membrane in the aqueous solution in S2 is 1-5min; the temperature during thermal crosslinking in S4 is 80-160°C, and the thermal crosslinking time is 2-10min.
8. The polyamide-based chemical cleaning agent according to claim 1, characterized in that: The preparation method of the chemical cleaning agent is: The raw materials are weighed according to the above mass percentages, and the weighed nonionic surfactant, zwitterionic surfactant, chelating agent, defoaming agent, organic solvent and water are stirred and mixed uniformly at 300-600 rpm and 50-80° C. to obtain a polyamide-based chemical cleaning agent.
9. A process for using a polyamide-based chemical cleaning agent, characterized in that: The following steps are involved: Step 1: Perform water flushing and water pressure test on the supercritical unit to be cleaned for 3-5 hours; Step 2: Fill the supercritical unit with superheater protection liquid and then pickle for 8-10 hours; Step 3: After pickling, rinse with water again for 3-6 hours; Step 4: using a polyamide-based chemical cleaning agent as claimed in claim 8 to rinse and passivate the supercritical unit; Step 5: Rinse with water after passivation is completed.
10. The process for using a polyamide-based chemical cleaning agent according to claim 9, characterized in that: During the rinsing and passivation in the fourth step, ultrasonic waves of 40 kHz and 200 W are used to assist the rinsing and passivation. The rinsing and passivation are first performed at 40-50° C. for 20-40 minutes, and then the temperature is raised to 70-80° C. for rinsing and passivation for 30-60 minutes.