Organic phosphonic acid coating, preparation method and application, and special pig

Abstract

The application provides an organic phosphonic acid coating and a preparation method thereof, and comprises the following raw materials according to weight percentage: vinyl chloride-vinylidene chloride-acrylic acid emulsion 30-38%, tannic acid 3-5%, aluminum tripolyphosphate 5-10%, ethylene glycol butyl ether 0.5-3.5%, titanium white powder 8-15%, silica powder 5-10%, wetting agent 0.3-0.8%, dispersant 0.5-2.0%, defoaming agent 0.2-0.6%, emulsion stabilizer 2-5%, thickening agent 0.1-0.4%, hydroxyethylidene diphosphonic acid 0.5-5%, and the rest is water. The aluminum tripolyphosphate in the organic phosphonic acid coating can form a chelate with various metal ions in the pipeline, form a passivation film on the inner wall of the pipeline, and effectively inhibit corrosion; the tannic acid can react with corrosion products to form a complex, the complex covers the corrosion sites to isolate oxygen and moisture, and prevents the corrosion sites from further corrosion; the hydroxyethylidene diphosphonic acid can form a complex with metal ions and form a protective film on the metal ions, can improve the adhesion of the coating, make the coating more firmly adhere to the inner wall of the pipeline, and improve the durability of the coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipeline coating, in particular to an organic phosphonic acid coating, a preparation method and application, and a special pig. BACKGROUND

[0002] The global climate warming problem is increasingly serious, and the CO2 emitted by burning fossil fuels is the main greenhouse gas, which contributes 70% to the greenhouse effect. The existing technology is to capture and purify the CO2 emitted in the production process of electric power and chemical industry, transport it to the nearby oil field, and inject it into the oil reservoir to realize CO2 geological sequestration and effectively improve the oil recovery rate. By 2050, 10 billion tons of CO2 will be captured and sequestered every year.

[0003] CO2 transportation is a key link for the large-scale development and application of CCUS technology. Pipeline transportation is considered to be the safest and most economical transportation method for CO2. In order to avoid the occurrence of two-phase flow and improve transportation efficiency, the captured CO2 is usually compressed to a supercritical state. When the temperature and pressure are above the critical point (31.2℃, 7.3MPa), CO2 enters a supercritical state. Supercritical CO2 has diffusion properties similar to gases and solubility similar to liquids, and also has low viscosity and low surface tension.

[0004] Generally, dry and pure CO2 has no corrosive effect on the pipeline. However, due to the limitations of CO2 sources, capture methods and costs, the supercritical CO2 fluid transported by the pipeline inevitably contains a certain amount of impurities such as H2O, O2, SO2 and NOx. Under the supercritical state, the mutual solubility of CO2 and water will be further increased, increasing the severity of pipeline corrosion; and the presence of O2, SO2 and NOx makes the supercritical CO2 phase system more complex, thereby promoting the corrosion of CO2 to the pipeline and increasing the operation risk of the supercritical CO2 transportation pipeline.

[0005] The existing pipeline internal anticorrosive coating cannot be used in the supercritical CO2 pipeline, because the supercritical CO2 fluid can dissolve the anticorrosive coating and cannot achieve the anticorrosive effect. Therefore, how to effectively inhibit the corrosion problem in the supercritical CO2 pipeline containing impurities has become a key to promoting the application and popularization of CCUS technology in China. Therefore, there is an urgent need for supercritical CO2 pipeline internal anticorrosive coating technology to effectively solve the corrosion problem in the supercritical CO2 pipeline containing impurities. SUMMARY

[0006] The technical problem to be solved by the present application is how to effectively solve the corrosion problem in the supercritical CO2 pipeline containing impurities.

[0007] The present application solves the above technical problems by the following technical means:

[0008] The first aspect of the present application provides an organic phosphonic acid coating, comprising the following raw materials in percentage by weight: vinyl chloride-vinylidene chloride-acrylic emulsion 30-38%, tannic acid 3-5%, aluminum tripolyphosphate 5-10%, ethylene glycol butyl ether 0.5-3.5%, titanium white 8-15%, silica powder 5-10%, wetting agent 0.3-0.8%, dispersant 0.5-2.0%, defoaming agent 0.2-0.6%, emulsion stabilizer 2-5%, thickening agent 0.1-0.4%, hydroxyethylidene diphosphonic acid 0.5-5%, and the rest is water.

[0009] Beneficial effects: The aluminum tripolyphosphate in the organic phosphonic acid coating of the present application can form a chelate with various metal ions in the pipeline, forming a passivation film on the inner wall of the pipeline, effectively inhibiting corrosion; the tannic acid can react with corrosion products to form a complex, which covers the corrosion sites to isolate oxygen and moisture, preventing further corrosion of the corrosion sites; the hydroxyethylidene diphosphonic acid can form a complex with metal ions and form a protective film on the metal ions, which can improve the adhesion of the coating, making the coating more firmly attached to the inner wall of the pipeline, and improving the durability of the coating.

[0010] The present application effectively solves the problem of corrosion in impurity-containing supercritical CO2 pipeline through the synergistic effect of aluminum tripolyphosphate, tannic acid and hydroxyethylidene diphosphonic acid. The organic phosphonic acid coating of the present application can react with corrosion products to form a stable internal anticorrosion protective coating, effectively reducing the risk of corrosion of the inner wall of the pipeline and ensuring the long-term stable operation of the pipeline.

[0011] Preferably, the wetting agent is a non-siloxane wetting agent.

[0012] Preferably, the dispersant is an acrylic ester copolymer dispersant.

[0013] Preferably, the defoaming agent is an organic silicon-based defoaming agent.

[0014] Preferably, the emulsion stabilizer is a non-ionic high molecular surfactant.

[0015] Preferably, the thickening agent is an organic bentonite.

[0016] The second aspect of the present application provides a preparation method of the above-mentioned organic phosphonic acid coating, comprising the following steps:

[0017] After dissolving ethylene glycol butyl ether in water, the thickening agent, emulsion stabilizer, wetting agent, dispersant and defoaming agent are added and stirred uniformly, and the aluminum tripolyphosphate, titanium white and silica powder are ground to obtain a coating base paste; under low-speed stirring, the hydroxyethylidene diphosphonic acid, vinyl chloride-vinylidene chloride-acrylic emulsion and tannic acid are added to the coating base paste to obtain an organic phosphonic acid coating.

[0018] Preferably, the grinding fineness is less than 40 μm.

[0019] The third aspect of the present application provides an application of the organic phosphonic acid coating, which is the above-mentioned organic phosphonic acid coating, and is used for the inner wall of the supercritical CO2 pipeline.

[0020] The fourth aspect of the present application provides a special pig, which is the above-mentioned organic phosphonic acid coating applied to the inner wall of the supercritical CO2 pipeline; the special pig is provided with a container tank and a nozzle, the container tank is arranged at the end of the special pig, and the nozzle is connected with the container tank.

[0021] Preferably, the special pig comprises a support shaft, which is arranged in parallel with the pipeline, and is provided with a motor and a sealed cabin, a control module is arranged inside the sealed cabin, and the motor is connected with the control module and the nozzle.

[0022] Preferably, the special pig is provided with a mileage wheel, which is vertically fixed on the support shaft, and is connected with the control module.

[0023] Preferably, leather cups are fixed at both ends of the support shaft, the number of the leather cups is 4, and the leather cups are evenly arranged at both ends of the support shaft. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Fig. 1 is a structural schematic diagram of the special pig in the present embodiment;

[0025] Figure 2 Fig. 4 is a polarization curve of the embodiment 1-2 and the comparative example 1-2;

[0026] Figure 3 Fig. 5 is a Nyquist curve of the embodiment 1-2 and the comparative example 1-2;

[0027] Figure 4 Fig. 6 is a linear polarization resistance curve of the embodiment 1-2 and the comparative example 1-2. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme of the embodiments of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0029] In the following embodiments, the test materials and reagents used, etc. can be obtained from commercial channels if no special instructions are given.

[0030] Unless otherwise indicated, the techniques and conditions employed in the examples are in accordance with the techniques and conditions described in the literature or according to the manufacturer's instructions.

[0031] Example 1

[0032] The present embodiment provides an organic phosphonic acid coating and a preparation method thereof, the organic phosphonic acid coating comprises the following raw materials according to weight percentage:

[0033] 30% of vinyl chloride-vinylidene chloride-acrylic emulsion, 4% of tannic acid, 5% of aluminum tripolyphosphate, 1% of ethylene glycol butyl ether, 10% of titanium white, 8% of silica powder, 0.5% of wetting agent, 1.0% of dispersant, 0.2% of defoaming agent, 3% of emulsion stabilizer, 0.3% of thickening agent, 3% of hydroxyethylidene diphosphonic acid, and the rest is deionized water.

[0034] The wetting agent is a non-siloxane wetting agent, and the present embodiment specifically uses TEGO Wet 500.

[0035] The dispersant is an acrylate copolymer dispersant, and the present embodiment specifically uses Dow PMA-20 of Dow Chemical.

[0036] The defoaming agent is an organic silicon-based defoaming agent, and the present embodiment specifically uses Air Product SA-10 of Air Products.

[0037] The emulsion stabilizer is a non-ionic high molecular surfactant, and the present embodiment specifically uses poloxamer 188.

[0038] The thickening agent is an organic bentonite.

[0039] The specific preparation method of the organic phosphonic acid coating is as follows:

[0040] After dissolving ethylene glycol butyl ether in deionized water, the organic bentonite, TEGO Wet 500, Dow PMA-20, Air Product SA-10, and poloxamer 188 are uniformly stirred, and then the aluminum tripolyphosphate, titanium white, and silica powder are added and ground, until the fineness is less than 40 um, to obtain the coating base paste.

[0041] Under low-speed stirring, the hydroxyethylidene diphosphonic acid, vinyl chloride-vinylidene chloride-acrylic emulsion, and tannic acid are added to the coating base paste to obtain the organic phosphonic acid coating.

[0042] Example 2

[0043] The present embodiment provides an organic phosphonic acid coating and a preparation method thereof, the organic phosphonic acid coating comprises the following raw materials according to weight percentage:

[0044] 35% of vinyl chloride-vinylidene chloride-acrylic emulsion, 3% of tannic acid, 7% of aluminum tripolyphosphate, 1% of ethylene glycol butyl ether, 10% of titanium white, 8% of silica powder, 0.5% of wetting agent, 1.0% of dispersant, 0.2% of defoaming agent, 3% of emulsion stabilizer, 0.3% of thickening agent, 5% of hydroxyethylidene diphosphonic acid, and the rest is deionized water.

[0045] The wetting agent is a non-siloxane wetting agent, and the specific embodiment uses TEGO Wet 500 from Degussa.

[0046] The dispersant is an acrylate copolymer dispersant, and the specific embodiment uses Dow PMA-20 from Dow Chemical.

[0047] The defoaming agent is a silicone-based defoaming agent, and the specific embodiment uses SA-10 from Air Product.

[0048] The emulsion stabilizer is a non-ionic high molecular surfactant, and the specific embodiment uses poloxamer 188.

[0049] The thickening agent is an organic bentonite.

[0050] The specific preparation method of the organic phosphonic acid coating is the same as that of Example 1, which will not be described here.

[0051] Example 3

[0052] The present embodiment provides an application and spraying method of an organic phosphonic acid coating. The organic phosphonic acid coating of Example 1 is sprayed on the inner wall surface of a supercritical CO2 pipeline by a special pig.

[0053] The special pig includes a support shaft 9 and a leather bowl 2, the support shaft 9 is arranged parallel to the pipeline, and two leather bowls are arranged at both ends of the support shaft 9. Figure 1 The shapes of the two leather bowls are different, and the shape from left to right in the horizontal direction is hexagonal and rectangular. Figure 1

[0054] A container pot 1 is arranged at the end of the support shaft 9, which is used to store the organic phosphonic acid coating. The container pot 1 is connected with a nozzle 3 through a pipeline, and the nozzle 3 is provided with two nozzles 3 arranged at both sides of the support shaft 9. The two nozzles 3 are connected through a pipeline, and a motor 4 is arranged in the middle of the pipeline. The motor 4 provides a spraying force for the nozzle 3, so that the organic phosphonic acid coating can be sprayed out of the nozzle 3. The motor 4 is fixed on the support shaft 9.

[0055] ​The middle part of the support shaft 9 is provided with a sealed cabin 5, the inside of the sealed cabin 5 is provided with a control module 6, the control module 6 is connected with the motor 4. The support shaft 9 is also provided with a mileage wheel 8, the mileage wheel 8 is vertically fixed on the support shaft 9, the mileage wheel 8 is connected with the control module 6, when the mileage wheel 8 reaches the target position, the control module 6 controls the motor 4 to rotate, and the nozzle 3 sprays the organic phosphonic acid coating.

[0056] The principle of the special pig of the embodiment is as follows:

[0057] The special pig of the embodiment is driven by the skin bowl 2 through the pressure difference in the pipeline, the pressure difference is controlled at 1-2 MPa; the special pig records the mileage through the mileage wheel 8, and compares with the mileage set in the control module 6. When the mileage is consistent, the control module 6 controls the motor 4 to start rotating, and controls the nozzle 3 to spray the organic phosphonic acid coating, and the spraying thickness is controlled at 50-150 μm.

[0058] Comparative example 1

[0059] The comparative example provides an organic phosphonic acid coating and a preparation method thereof, and the difference between the comparative example and the embodiment 1 is that the weight percentage of the tannic acid is 2.5%.

[0060] Comparative example 2

[0061] The comparative example provides a pipeline coating and a preparation method thereof, and the pipeline coating comprises the following raw materials according to the weight percentage:

[0062] 53% of acrylic emulsion, 22% of titanium white, 0.9% of dispersant, 0.4% of wetting agent, 0.2% of defoaming agent, 0.4% of thickening agent, 3% of dipropylene glycol methyl ether, 2% of ester alcohol twelve, 0.2% of ammonia water, and the remaining proportion is deionized water.

[0063] The wetting agent is a non-siloxane wetting agent, and the specific use of the embodiment is TEGO Wet 500 of Di Guo.

[0064] The dispersant is an acrylate copolymer dispersant, and the specific use of the embodiment is Dow PMA-20 of Dow Chemical.

[0065] The defoaming agent is an organic silicon type defoaming agent, and the specific use of the embodiment is Air Product SA-10 of Air Product.

[0066] The thickening agent is an organic bentonite.

[0067] The preparation method of the pipeline coating is the same as that of the embodiment 1, and will not be described here.

[0068] Experimental example

[0069] The coatings of Examples 1-2 and Comparative Examples 1-3 were sprayed onto rusted steel plates, and the anti-corrosion performance of the coatings was evaluated by CO2 simulated medium environment test.

[0070] 1. Simulated CO2 environment at ambient temperature and pressure: The temperature was 25℃, the test pressure was 0.1 MPa, and the pH was 2.87. The electrochemical properties of the coating were evaluated. The results are as follows: Figures 2-4 As shown.

[0071] 2. High-temperature and high-pressure CO2 simulated medium environment: The rusted steel plate was immersed in a CO2 medium containing 200ppm of impurities (O2 / H2S / SO2 / NO2) at a temperature of 50℃ and a test pressure of 10MPa for 7 days to evaluate the weight gain of the coating. The results are shown in Table 1.

[0072] Table 1

[0073]

[0074] In a simulated CO2 medium environment at normal temperature and pressure, the corrosion potential, corrosion current density, and impedance were tested. The larger the corrosion potential, the smaller the corrosion current density, and the larger the absolute value of the impedance at 0.01 Hz, the better the corrosion resistance of the coating. In a simulated CO2 medium environment at high temperature and pressure, the weight gain rate was tested. The smaller the weight gain rate, the better the corrosion resistance of the coating.

[0075] according to Figures 2-4 Calculations yielded Table 1, which contains relevant data on a simulated CO2 medium environment at normal temperature and pressure. According to the data in Table 1, the coatings of Examples 1-2 have better corrosion resistance than those of Comparative Examples 1-2.

[0076] according to Figure 2 As shown, the smaller i is, the larger E is, and the better the corrosion resistance of the material. The figure shows the corrosion resistance effect of the coating: Example 1 > Example 2 > Comparative Example 1 > Comparative Example 2.

[0077] according to Figure 3 As shown, a larger capacitive arc radius indicates greater charge transfer resistance and a lower corrosion rate. The figure shows the corrosion resistance of the coatings in the order: Example 1 > Example 2 > Comparative Example 1 > Comparative Example 2.

[0078] according to Figure 4 As shown, the greater the slope of the curve, the better the corrosion resistance of the material. The figure shows the corrosion resistance effect of the coatings in the order: Example 1 > Example 2 > Comparative Example 1 > Comparative Example 2.

[0079] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. The application of an organophosphonic acid coating on the inner wall of a supercritical CO2 pipeline, characterized in that, Organophosphonic acid coatings comprise the following raw materials by weight percentage: vinyl chloride-vinylidene chloride-acrylic acid emulsion 30-38%, tannic acid 3-5%, aluminum tripolyphosphate 5-10%, ethylene glycol butyl ether 0.5-3.5%, titanium dioxide 8-15%, silicone powder 5-10%, wetting agent 0.3-0.8%, dispersant 0.5-2.0%, defoamer 0.2-0.6%, emulsion stabilizer 2-5%, thickener 0.1-0.4%, hydroxyethylidene diphosphonic acid 0.5-5%, with the remainder being water.

2. The application of the organophosphonic acid coating according to claim 1 in the inner wall of a supercritical CO2 pipeline, characterized in that... The wetting agent is a non-siloxane wetting agent; the dispersant is an acrylate copolymer dispersant.

3. The application of the organophosphonic acid coating according to claim 1 in the inner wall of a supercritical CO2 pipeline, characterized in that, The defoamer is an organosilicon defoamer; the emulsion stabilizer is a nonionic polymeric surfactant; and the thickener is organic bentonite.

4. The application of the organophosphonic acid coating according to any one of claims 1-3 in the inner wall of a supercritical CO2 pipeline, characterized in that, Includes the following steps: After dissolving ethylene glycol butyl ether in water, thickener, emulsion stabilizer, wetting agent, dispersant, and defoamer are added and stirred evenly. Aluminum tripolyphosphate, titanium dioxide, and silica powder are added and ground to obtain a coating base slurry. Under low-speed stirring, hydroxyethylidene diphosphonic acid, vinyl chloride-vinylidene chloride-acrylic acid emulsion, and tannic acid are added to the coating base slurry to obtain an organophosphonic acid coating.

5. The application of the organophosphonic acid coating according to claim 4 in the inner wall of a supercritical CO2 pipeline, characterized in that, The fineness of the grinding process is less than 40 μm.

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