A scale inhibitor for circulating water and its application

Abstract

This invention belongs to the field of circulating water treatment technology, specifically relating to a circulating water scale inhibitor, comprising the following components by weight percentage: 3-7 parts tannin, 3-7 parts sodium gluconate, 5-15 parts polyaspartic acid, 5-15 parts sodium polyacrylate, 5-15 parts itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer, 10-20 parts zinc sulfate, 10-20 parts sodium orthosilicate, 15-25 parts sodium citrate, and 5-15 parts sodium dodecylbenzenesulfonate. This invention selects water treatment agents with good biodegradability and optimizes their formulation to successfully prepare a phosphorus-free, environmentally friendly, and high-performance circulating water corrosion and scale inhibitor; it does not contain nitrites, phosphates, or other substances that cause water pollution, is green and environmentally friendly, easy to use, and low in cost.

Description

Technical Field

[0001] This invention belongs to the field of circulating water treatment technology, specifically relating to a circulating water scale inhibitor and its preparation and application. Background Technology

[0002] Cooling water circulates in an open-loop cooling system. Due to factors such as rising water temperature, changes in water flow velocity, water evaporation, concentration of various inorganic ions and organic substances, exposure of the cooling tower and cooling water to outdoor sunlight, wind and rain, and the entry of dust and debris, as well as the combined effects of equipment structure and materials, if the water quality is not treated or the water treatment is inadequate, the system will develop three major problems: serious deposit adhesion (scaling), equipment corrosion, and the proliferation of microorganisms. In addition, the resulting slime and dirt will clog the pipes, which will seriously threaten and damage the operation of the production equipment and cause huge economic losses to the enterprise.

[0003] Deposits are collectively referred to as scale, which is divided into scale (hard scale) and sludge (soft scale). Sludge includes silt, slime, and corrosion products. Scale, also known as hard scale or inorganic scale, is formed when insoluble or slightly soluble salts introduced into the water change conditions in the circulating water. Common examples include calcium carbonate, calcium phosphate, calcium sulfate, magnesium hydroxide, and magnesium silicate. Sludge, also known as soft scale, often contains mud, dust, sand, corrosion products, natural organic matter, microbial colonies and secretions, ferric phosphate, alumina, aluminum phosphate, and general debris.

[0004] Both hard and soft scale deposits on heat exchangers can impair heat transfer, leading to decreased heat exchanger efficiency. In severe cases, they can clog heat exchangers, increasing system resistance, reducing the efficiency of water pumps and cooling towers, and increasing production energy consumption. Furthermore, soft scale promotes under-deposit corrosion, a localized corrosion that is more harmful than general corrosion and can cause water coolers to perforate. In particular, under-deposit corrosion caused by microbial slime can lead to water cooler leaks in a short period, and even cause abnormal production shutdowns.

[0005] In circulating cooling water system water treatment, the main methods for addressing scaling issues include removing scale-forming ions from the cooling water, adding acid or CO2 to lower the pH, stabilizing bicarbonates, adding scale inhibitors, reducing makeup water turbidity, and adding side-stream filtration facilities. Based on the characteristics and water quality properties of the circulating cooling water system, using appropriate corrosion and scale inhibitors and bactericides and algaecides can reduce the damage caused by corrosion, scaling, and microbial growth of metal materials in the system, extend the system's service life, improve equipment and water utilization, and achieve water and energy conservation. Currently, commonly used scale and corrosion inhibitor formulations easily cause eutrophication of water bodies, resulting in environmental pollution, and are inconvenient to use, have poor scale inhibition effects, and are costly. Low-phosphorus, phosphorus-free, and nitrite-free scale inhibitors have become the main research direction. Therefore, it is necessary to develop a circulating water scale inhibitor to solve these problems, reduce environmental pollution, and lay a good foundation for water conservation and emission reduction. Summary of the Invention

[0006] To achieve the above objectives, the technical solution adopted by the present invention is to provide a circulating water scale inhibitor and its preparation and application.

[0007] A circulating water scale inhibitor comprises the following components in weight percentage: 3-7 parts tannin, 3-7 parts sodium gluconate, 5-15 parts polyaspartic acid, 5-15 parts sodium polyacrylate, 5-15 parts itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer, 10-20 parts zinc sulfate, 10-20 parts sodium orthosilicate, 15-25 parts sodium citrate, and 5-15 parts sodium dodecylbenzenesulfonate.

[0008] Preferably, the circulating water scale inhibitor comprises the following components in weight percentage: 4-6 parts tannin, 4-6 parts sodium gluconate, 8-12 parts polyaspartic acid, 8-12 parts sodium polyacrylate, 8-12 parts itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer, 13-17 parts zinc sulfate, 13-17 parts sodium orthosilicate, 18-22 parts sodium citrate, and 8-12 parts sodium dodecylbenzenesulfonate.

[0009] Preferably, the circulating water scale inhibitor comprises the following components in weight percentage: 5 parts tannin, 5 parts sodium gluconate, 10 parts polyaspartic acid, 10 parts sodium polyacrylate, 10 parts itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer, 15 parts zinc sulfate, 15 parts sodium orthosilicate, 20 parts sodium citrate, and 10 parts sodium dodecylbenzenesulfonate.

[0010] The circulating water scale inhibitor described in this invention is used in water treatment for corrosion inhibition and scale inhibition.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] This invention selects a water treatment agent with good biodegradability and optimizes its compounding to successfully prepare a phosphorus-free, environmentally friendly, and high-performance circulating water corrosion and scale inhibitor; it does not contain substances that cause water pollution such as nitrite and phosphate, is green and environmentally friendly, easy to use, and low in cost; this scale and corrosion inhibitor meets the optimal first-class discharge standard of GB 8978-2002.

[0013] The scale inhibitor of this invention exhibits excellent synergistic effects among its components, and possesses excellent corrosion inhibition and scale inhibition properties, with a corrosion inhibition rate of 99.85% and a scale inhibition rate of 98.4%. Detailed Implementation

[0014] To further understand the present invention, the present invention will be described in detail below with reference to embodiments.

[0015] Example 1: Performance Test of Circulating Water Scale Inhibitor

[0016] The scale inhibitor for circulating water of this invention is formulated according to the composition and content shown in Table 1.

[0017] Table 1 Formulation of scale inhibitor for circulating water

[0018] ,

[0019] The above-mentioned raw materials can be purchased from the market or synthesized in-house. Among them, the itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer and the acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer (AA / AMPS) copolymer are prepared using conventional methods.

[0020] Performance testing methods:

[0021] Scale inhibition performance test

[0022] The scale inhibition performance of the circulating water scale inhibitor was tested in accordance with GB / T 16632—2019 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Precipitation Method".

[0023] Blank test water without scale inhibitor and test water with scale inhibitor added were placed in Erlenmeyer flasks and immersed in a constant temperature water bath at (80±1) ℃ for 10 h. The solution was then filtered dry under hot conditions using medium-speed quantitative filter paper. After cooling, a certain amount of the filtrate was transferred and the Ca2+ was determined by EDTA titration. + concentration.

[0024] Calculation formula: .

[0025] In the formula: η represents the scale inhibition rate, and c1 represents the Ca2+ after adding the scale inhibitor test solution. + Mass concentration, c0 represents the Ca2+ concentration after a blank test without scale inhibitor.+ Mass concentration, c represents the calcium ion mass concentration in water under actual operating conditions.

[0026] Corrosion inhibition performance test

[0027] The corrosion inhibition performance of scale inhibitors for circulating water was determined according to GB / T 18175-2014, "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotary Coated Plate Method". The test water was laboratory tap water. A SCRC-Ⅲ type rotary coated plate corrosion tester was used. The test settings were: water bath temperature 45 ℃, rotation speed 105 r / min, test duration 72 h. The test specimens were A3 carbon steel type I specimens, measuring 50 mm × 25 mm × 2 mm, with a total area of ​​approximately 28 cm² for each specimen. 2 Five parallel samples were prepared for each test group, and the average value was taken. The samples were degreased, cleaned, dried, weighed, and recorded before testing. After testing, the corrosion products were first brushed off with a brush, rinsed, and then placed in the pickling solution for 30 seconds. After rinsing, they were placed in the alkaline pickling solution for 30 seconds, rinsed, dried, and then placed in anhydrous ethanol for 3 minutes. After drying, the samples were weighed and recorded.

[0028] Calculation formula: ; .

[0029] In the formula: μ represents the corrosion rate, m represents the mass loss value of the test piece, m0 represents the average mass loss value of the test piece in the acid pickling blank test, s represents the surface area value of the test piece, ρ represents the density value of the test piece, t represents the test time value, β represents the corrosion inhibition rate, μ0 represents the corrosion rate of the test piece in the blank test, μ1 represents the corrosion rate of the test piece, and 8760 is the number of hours equivalent to a year, in hours per year (h / a).

[0030] Performance test results

[0031] Table 2 Performance test results of scale inhibitor for circulating water

[0032] ,

[0033] Note: Scale inhibitor concentration 100 mg / L

[0034] As shown in Table 2, compared with formulations A2-A8, formulation A1 has excellent corrosion inhibition and scale inhibition properties, with a corrosion inhibition rate of 99.85% and a scale inhibition rate of 98.4%.

[0035] In this application, tannins and sodium gluconate possess both corrosion inhibition and scale inhibition properties; polyaspartic acid, sodium polyacrylate, and itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) mainly function as scale inhibitors; zinc sulfate, sodium orthosilicate, and sodium citrate mainly function as corrosion inhibitors. The components in this application work synergistically, and the specific mechanism is as follows:

[0036] The scale inhibition effect of the compound scale inhibitor and corrosion inhibitor of this invention is mainly achieved through the added scale inhibitor monomers. The scale inhibitor molecule has multiple or more functional groups, and will simultaneously exhibit chelation, adsorption and dispersion effects under different water quality conditions. It changes the crystallization pattern of scale through physical and chemical processes, making it appear in a dissolved or suspended state, thus preventing the formation of a large amount of scale.

[0037] In this invention, the corrosion inhibition performance of the compound scale and corrosion inhibitor mainly relies on the added corrosion inhibitor to play a leading role, while some scale inhibitors that simultaneously inhibit scale and corrosion play an auxiliary role. There is electrostatic attraction and intermolecular force between the surface of the corrosion inhibitor molecules and the metal. When the corrosion inhibitor molecules are continuously adsorbed on the metal surface, the adsorption layer formed greatly blocks the contact between the metal and the corrosive medium, thus inhibiting the occurrence of corrosion.

[0038] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A scale inhibitor for circulating water, characterized in that, It consists of the following components in weight percentage: tannin 4-6 parts, sodium gluconate 4-6 parts, polyaspartic acid 8-12 parts, sodium polyacrylate 8-12 parts, itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer 8-12 parts, zinc sulfate 13-17 parts, sodium orthosilicate 13-17 parts, sodium citrate 18-22 parts, and sodium dodecylbenzenesulfonate 8-12 parts.

2. The circulating water scale inhibitor according to claim 1, characterized in that, It consists of the following components in weight percentage: 5 parts tannin, 5 parts sodium gluconate, 10 parts polyaspartic acid, 10 parts sodium polyacrylate, 10 parts itaconic acid / 2-acrylamide-2-methylpropanesulfonic acid (IA / AMPS) copolymer, 15 parts zinc sulfate, 15 parts sodium orthosilicate, 20 parts sodium citrate, and 10 parts sodium dodecylbenzenesulfonate.

3. The use of the circulating water scale inhibitor according to any one of claims 1-2 in water treatment.

4. The use according to claim 3, characterized in that, Used for corrosion inhibition and scale inhibition.