A corrosion and scale inhibitor suitable for highly corrosive refinery circulating water and its preparation method

Abstract

This invention discloses a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water and its preparation method. The invention first reacts 3-bromopropionic acid with 1-vinylimidazole to prepare 1-vinyl-3-propionic acid imidazole bromide. Then, through the reaction of double bonds with thiol groups, an ionic liquid polymer is prepared. The ionic liquid polymer prepared by this invention can adsorb onto metal surfaces, forming a protective film that protects the metal from corrosion by harmful media, thereby slowing down the corrosion rate and achieving a good corrosion inhibition effect. Simultaneously, through reaction with mercaptoacetic acid, the content of carboxyl groups in the ionic liquid is further enriched. These carboxyl groups can react with Ca in water... 2+ Mg 2+ The isocations form stable soluble chelates, effectively preventing the formation of calcium carbonate and calcium phosphate.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a corrosion and scale inhibitor suitable for circulating water in highly corrosive refineries and its preparation method. Background Technology

[0002] With increasing emphasis on environmental protection, there is an urgent need for refining and chemical enterprises to conserve fresh makeup water as much as possible in their circulating water systems. Since most refineries currently use open-loop circulating cooling water circuits, it is inevitable that impurities will enter the circulating system and pollute the water, and microorganisms will grow during the daily operation of the circulating water system. In addition, the significant increase in the concentration ratio will lead to corrosion or scaling of the water, which will greatly increase the risk of leakage and blockage of heat exchange equipment and related pipelines.

[0003] Currently, using corrosion and scale inhibitors to control the quality of circulating water is a common method. The main monomers of corrosion and scale inhibitors are nitrites, chromates, zinc salts, organophosphonates, and silicates. Among these monomers, some have the disadvantages of high toxicity and easy decomposition when exposed to heat and chlorine, and have gradually become unable to meet the requirements of corrosion and scale inhibitors for industrial circulating water.

[0004] Chinese patent document CN201510937725.8 provides a corrosion and scale inhibitor for industrial circulating water. Its components, by mass percentage, are: 30-56% organophosphorus, 10-15% acrylic acid-2-methyl-2-acrylamidopropanesulfonic acid copolymer, 4-10% zinc salt, and the remainder is water. The corrosion and scale inhibitor for industrial circulating water provided by this patent has low toxicity and can withstand harsh conditions such as high temperature and chloride, thereby reducing the cost of the agent and improving the corrosion and scale inhibition effect. However, the treatment effect is not good when treating water with high concentration ratio. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water and its preparation method. The prepared corrosion and scale inhibitor is mainly applied to refinery circulating water with a strong tendency to corrode, and has good anti-corrosion and scale inhibition effects under high concentration conditions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water, which is composed of the following raw materials in parts by weight: 40-60 parts of phosphonocarboxylic acid polymer (POCA), 5-20 parts of zinc salt, 10-30 parts of coordination compound, and 5-10 parts of ionic liquid polymer.

[0008] The coordination compound is selected from 2-hydroxyphosphonoacetic acid (HPAA) or 2-phospho-1,2,4-tricarboxylate butane (PBTCA);

[0009] The preparation method of ionic liquid polymers is as follows:

[0010] S1. Add 3-bromopropionic acid to acetonitrile solvent, stir until homogeneous, then add 1-vinylimidazolium, stir and reflux to react. After the reaction is complete, extract with anhydrous diethyl ether, take the lower oily substance and dry it under vacuum to obtain an oily liquid.

[0011] S2. Add the oily liquid to toluene, then add mercaptoacetic acid and azobisisobutyronitrile, mix well, purge with nitrogen to purge air, seal and react in a water bath. After the reaction is complete, extract with anhydrous diethyl ether, take the lower oily substance and dry it under vacuum to obtain the ionic liquid polymer.

[0012] Preferably, in step S1, the molar ratio of 3-bromopropionic acid to 1-vinylimidazole is 10:1.1.

[0013] Preferably, in step S1, the temperature of the stirring and reflux reaction is 60-80℃, and the stirring and reflux reaction time is 3-5h.

[0014] Preferably, in step S2, the mass ratio of the oily liquid, mercaptoacetic acid, and azobisisobutyronitrile is 5-10:3-6:0.5-1.

[0015] Preferably, in step S2, the temperature of the water bath reaction is 80-120℃, and the reaction time is 8-12h.

[0016] As a preferred embodiment, the corrosion and scale inhibitor is composed of the following raw materials in parts by weight: 40-50 parts phosphonocarboxylic acid polymer, 5-10 parts zinc salt, 10-20 parts coordination compound, and 5-10 parts ionic liquid polymer.

[0017] Preferably, the zinc salt is a soluble zinc salt, and more preferably, the soluble zinc salt is selected from zinc sulfate, zinc chloride, or zinc acetate.

[0018] Secondly, the present invention provides a method for preparing the above-mentioned corrosion and scale inhibitor, comprising the following steps: mixing phosphonocarboxylic acid polymer, zinc salt, coordination compound, and ionic liquid polymer evenly according to weight parts, and then allowing it to stand to obtain the corrosion and scale inhibitor.

[0019] Preferably, the mixing temperature is 20-40℃, the mixing time is 1-2 hours, and the mixing speed is 400-800 r / min.

[0020] Thirdly, the present invention also provides the application of the above-mentioned corrosion and scale inhibitor in highly corrosive refinery circulating water.

[0021] Preferably, the dosage of corrosion and scale inhibitor is 5-10 mg / L.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention first reacts 3-bromopropionic acid with 1-vinylimidazole to prepare 1-vinyl-3-propionic acid imidazole bromide. Then, it utilizes the reaction of double bonds with thiol groups to prepare an ionic liquid polymer. The ionic liquid polymer prepared by this invention can adsorb on the metal surface to form a protective film, protecting the metal from corrosion by harmful media, thereby slowing down the corrosion rate of the metal and achieving a good corrosion inhibition effect. At the same time, through reaction with mercaptoacetic acid, the content of carboxyl groups in the ionic liquid is further enriched. Carboxyl groups can react with Ca in water. 2+ Mg 2+ The isocations form stable soluble chelates, effectively preventing the formation of calcium carbonate and calcium phosphate.

[0024] (2) The corrosion and scale inhibitor provided by the present invention is composed of organic and inorganic corrosion and scale inhibitors and dispersants. The formulation components have obvious synergistic effects, good compatibility with bactericides, good tolerance to iron ions and halogens, convenient operation, and excellent comprehensive performance. At the same time, the product of the present invention can be added to the reactor in proportion at room temperature and stirred evenly. The addition method is simple, the components are easy to compound, and the product has good stability.

[0025] (3) The present invention has significant effects. When treating highly corrosive water with a water quality stability index (RSI) value of 8.8 or higher, the corrosion rate of carbon steel can be reduced to about 0.03 mm / a. The polymeric dispersant in the formula can effectively slow down the deposition of scale on the surface of the metal heat exchanger wall, so that the scale inhibition rate of the formula for calcium carbonate and calcium phosphate can reach more than 98%, which can significantly reduce the scale inhibition layer formation rate on the metal heat exchange surface, thereby greatly saving the amount of fresh water replenishment. It can be promoted and used in refinery circulating water systems under similar conditions. Detailed Implementation

[0026] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0027] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0028] The phosphonocarboxylic acid polymer used in this invention was purchased from Shandong Taihe Technology Co., Ltd., and its solid content is ≥30.0%.

[0029] The preparation method of ionic liquid polymers is as follows:

[0030] S1. Add 10 mmol of 3-bromopropionic acid to 10 mL of acetonitrile solvent, stir well, then add 1.1 mmol of 1-vinylimidazole, stir and reflux at 60 °C for 4 h. After the reaction is completed, extract three times with anhydrous diethyl ether, take the lower oily substance and dry it under vacuum at 60 °C for 12 h to obtain an oily liquid.

[0031] S2. Add 8g of oily liquid to 50mL of toluene, then add 4g of mercaptoacetic acid and 1g of azobisisobutyronitrile, mix well, purge with nitrogen to remove air, seal and react in a water bath at 80℃ for 12h. After the reaction is complete, extract with anhydrous diethyl ether, take the lower oily substance and dry it under vacuum at 60℃ for 12h to obtain the ionic liquid polymer.

[0032] Example 1

[0033] A method for preparing a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water is as follows:

[0034] 40 parts of phosphonocarboxylic acid polymer, 10 parts of zinc sulfate, 20 parts of 2-hydroxyphosphonoacetic acid, and 10 parts of ionic liquid polymer were stirred and mixed at 25°C for 2 hours at a stirring speed of 600 r / min, and then allowed to stand to obtain a corrosion and scale inhibitor.

[0035] Example 2

[0036] A method for preparing a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water is as follows:

[0037] 60 parts of phosphonocarboxylic acid polymer, 15 parts of zinc chloride, 10 parts of 2-hydroxyphosphonoacetic acid, and 6 parts of ionic liquid polymer were stirred and mixed at 25°C for 2 hours at a stirring speed of 400 r / min, and then allowed to stand to obtain the corrosion and scale inhibitor.

[0038] Example 3

[0039] A method for preparing a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water is as follows:

[0040] 45 parts of phosphonocarboxylic acid polymer, 5 parts of zinc chloride, 30 parts of 2-hydroxyphosphonoacetic acid, and 8 parts of ionic liquid polymer were stirred and mixed at 25°C for 2 hours at a stirring speed of 800 r / min, and then allowed to stand to obtain the corrosion and scale inhibitor.

[0041] Example 4

[0042] A method for preparing a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water is as follows:

[0043] 50 parts of phosphonocarboxylic acid polymer, 10 parts of zinc sulfate, 15 parts of 2-phospho-1,2,4-tricarboxylic acid butane, and 7 parts of ionic liquid polymer were stirred and mixed at 25°C for 2 hours at a stirring speed of 800 r / min, and then allowed to stand to obtain the corrosion and scale inhibitor.

[0044] Comparative Example 1

[0045] A method for preparing a corrosion and scale inhibitor is as follows:

[0046] 40 parts of phosphonocarboxylic acid polymer, 10 parts of zinc sulfate, 20 parts of 2-hydroxyphosphonoacetic acid, and 10 parts of acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer were stirred and mixed at 25°C for 2 hours at a stirring speed of 600 r / min, and then allowed to stand to obtain the corrosion and scale inhibitor.

[0047] Comparative Example 2

[0048] A method for preparing a corrosion and scale inhibitor is as follows:

[0049] 40 parts of phosphonocarboxylic acid polymer, 10 parts of zinc sulfate, and 20 parts of 2-hydroxyphosphonoacetic acid were stirred and mixed at 25°C for 2 hours at a stirring speed of 600 r / min, and then allowed to stand to obtain a corrosion and scale inhibitor.

[0050] Comparative Example 3

[0051] A method for preparing a corrosion and scale inhibitor suitable for highly corrosive refinery circulating water is as follows:

[0052] 40 parts of phosphonocarboxylic acid polymer, 10 parts of zinc sulfate, 20 parts of 2-hydroxyphosphonoacetic acid, and 10 parts of ionic liquid were stirred and mixed at 25°C for 2 hours at a stirring speed of 600 r / min, and then allowed to stand to obtain a corrosion and scale inhibitor.

[0053] The preparation method of the ionic liquid is as follows: 10 mmol of 3-bromopropionic acid is added to 10 mL of acetonitrile solvent and stirred evenly. Then, 1.1 mmol of 1-vinylimidazole is added, and the mixture is stirred and refluxed at 60 °C for 4 h. After the reaction is completed, the mixture is extracted three times with anhydrous diethyl ether. The lower oily substance is then dried under vacuum at 60 °C for 12 h to obtain the ionic liquid.

[0054] The corrosion and scale inhibitors prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests. The dosage of the corrosion and scale inhibitors was 5 mg / L. The specific test steps are as follows:

[0055] Corrosion inhibition performance test: conducted according to GB / T18175-2014 standard, test temperature 45℃, test time 72h, the material of the coupon is Q245R, the stirring linear speed is 0.33m / s, a circulating water sample provided by a refining and chemical enterprise, pH=8.32, conductivity 1054.9μS / cm, total hardness (calcium carbonate) 75.21mg / L, calcium hardness 32.75mg / L, total alkalinity 59.7mg / L, chloride ion 80.03mg / L, sulfate ion 59.80mg / L;

[0056] Calcium carbonate scale inhibition test: The test was conducted in accordance with GB / T 16632-2019 "Determination of scale inhibition performance of water treatment agents - calcium carbonate deposition method" standard;

[0057] Calcium phosphate scale inhibition test: The test was conducted in accordance with GB / T 22626-2008 "Determination of scale inhibition performance of water treatment agents - calcium phosphate deposition method" standard;

[0058] The test results are shown in Table 1:

[0059] Table 1

[0060] Corrosion rate (mm / a) Calcium carbonate scale inhibition rate (%) Calcium phosphate scale inhibition rate (%) Example 1 0.023 99.3 99.6 Example 2 0.038 98.2 98.9 Example 3 0.029 98.9 99.5 Example 4 0.035 98.6 99.3 Comparative Example 1 0.071 91.4 89.7 Comparative Example 2 1.436 82.2 80.4 Comparative Example 3 0.054 90.8 91.2

[0061] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A corrosion and scale inhibitor suitable for highly corrosive refinery circulating water, characterized in that, It is composed of the following raw materials in parts by weight: 40-60 parts phosphonocarboxylic acid polymer, 5-20 parts zinc salt, 10-30 parts coordination compound, and 5-10 parts ionic liquid polymer; The coordination compound is selected from 2-hydroxyphosphonoacetic acid or 2-phospho-1,2,4-tricarboxylic acid butane; The zinc salt is selected from zinc sulfate, zinc chloride, or zinc acetate; The preparation method of ionic liquid polymers is as follows: S1. Add 3-bromopropionic acid to acetonitrile solvent, stir until homogeneous, then add 1-vinylimidazolium, stir and reflux to react. After the reaction is complete, extract with anhydrous diethyl ether, take the lower oily substance and dry it under vacuum to obtain an oily liquid. S2. Add the oily liquid to toluene, then add mercaptoacetic acid and azobisisobutyronitrile, mix well, purge with nitrogen to purge air, seal and react in a water bath. After the reaction is complete, extract with anhydrous diethyl ether, take the lower oily substance and dry it under vacuum to obtain the ionic liquid polymer.

2. The corrosion and scale inhibitor suitable for highly corrosive refinery circulating water according to claim 1, characterized in that, In step S1, the molar ratio of 3-bromopropionic acid to 1-vinylimidazole is 10:1.

1.

3. The corrosion and scale inhibitor suitable for highly corrosive refinery circulating water according to claim 1, characterized in that, In step S1, the temperature of the stirring and reflux reaction is 60-80℃, and the stirring and reflux reaction time is 3-5h.

4. The corrosion and scale inhibitor suitable for highly corrosive refinery circulating water according to claim 1, characterized in that, In step S2, the mass ratio of the oily liquid, mercaptoacetic acid, and azobisisobutyronitrile is 5-10:3-6:0.5-1.

5. The corrosion and scale inhibitor suitable for highly corrosive refinery circulating water according to claim 1, characterized in that, In step S2, the temperature of the water bath reaction is 80-120℃, and the reaction time is 8-12h.

6. The method for preparing the corrosion and scale inhibitor according to any one of claims 1-5, characterized in that, The process includes the following steps: mixing the phosphonocarboxylic acid polymer, zinc salt, coordination compound, and ionic liquid polymer in parts by weight until homogeneous, and then allowing it to stand to obtain the corrosion and scale inhibitor.

7. The preparation method according to claim 6, characterized in that, The mixing temperature is 20-40℃, the mixing time is 1-2 hours, and the mixing speed is 400-800 r / min.

8. The application of the corrosion and scale inhibitor as described in any one of claims 1-5 in highly corrosive refinery circulating water.

9. The application according to claim 8, characterized in that, When using, the dosage of corrosion and scale inhibitor is 5-10 mg / L.