RU2482223C2 - Agent for removing rust, scum and other mineral deposits based on glyoxal and derivatives thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: agent for removing rust, scum and other mineral deposits contains components in the following ratio, wt %: 20-40 hydrochloric acid, 1-3 soluble corrosion inhibitor, 2-10 glyoxal, 0.5-2 glyoxalic acid, 0.5-2 glycolic acid, 0.5-2 glycolaldehyde, 0.01 antifoaming agent, water - the balance.

EFFECT: agent has high efficiency in terms of removing inorganic deposits of a different composition and low level of corrosive action.

2 tbl, 4 ex

Description

The present invention relates to chemical means for removing rust, scale and mineral deposits from metal surfaces.

The tool can be used to remove scale and rust from the internal surfaces of heat exchangers, heating elements, pipelines, boilers, boilers, heating systems, rust cleaning of various parts and mechanisms.

A known composition for cleaning surfaces from mineral deposits of various origins (RF Patent 2160307, C11D 7/32, C11D 7/08, C11D 7/10, publ. 10.12.2000). The tool is used for cleaning technological equipment (pasteurizers, sterilizers, etc.) and in other areas of the agricultural sector, in boiler cleaning, for cleaning the surfaces of heat exchangers, tanks, pipelines, etc. from scale. The main active agent is a mixture of nitric acid with urea in a molar ratio of 1: 1. The use of nitric acid as an active agent, which is relatively weak, is not effective in case of large volumes of deposits of mineral origin.

There is a technology of scale deposits from the surface of products using means containing complexon (24.0-24.6 g / l) and ascorbic acid (1.0-3.0 g / l) (RF Patent 2114215, C23F 14/02, C23G 1/06, publ. 06/27/1998). The composition is effective when cleaning the surface of products containing small deposits, with a large volume of deposits, special requirements are placed on the intensity of their removal, there is an overrun of the product, there is a need for additional heating, an increase in the time for cleaning, etc.

In cases where there is a strong degree of contamination of the object, and also the nature of inorganic deposits is unknown, strong mineral acids are used - sulfuric, hydrochloric and phosphoric. The use of sulfuric acid leads to increased corrosion of technological equipment, especially if it is made of ordinary grades of steel.

Closest to the proposed one is a composition for removing high-temperature mineral scaling from power equipment, containing nitrile tri (methylenephosphonic) acid - 14-16%, methyliminodimethylenephosphonic acid - 4-7%, hydrochloric acid -10-14%, acid corrosion inhibitor - 0.5 -1 (RF Patent 2177458 C02F 5/14, C23F 14/02, publ. 12/27/2001).

The disadvantage of the proposed composition is the high cost of the components used, as well as the relatively low efficiency when removing large volumes of mineral deposits.

In industrial pipelines and assemblies that are constantly in contact with aggressive chemical media, salt solutions and other process fluids, a large volume of dense deposits is formed, consisting of metal oxides, scale deposits (calcium and magnesium carbonates), metal interaction products with aggressive chemical media (salts and metal oxides). With continuous non-stop operation, a large volume of deposits is formed, significantly reducing the throughput of pipelines (reducing the internal diameter) and the efficiency of the technological equipment. To effectively remove such deposits, a composition is required that has a high dissolving power with respect to deposits, but at the same time with minimal impact on the metal surfaces being cleaned. Another requirement is the low cost of the drug, because to remove a large number of deposits requires a large expenditure of funds.

The objective of the present invention is to develop a universal tool for the effective removal of large volumes of scale, rust and other mineral deposits from metal surfaces, which has a reduced corrosive effect on the treated surfaces, cheaper means.

This object is achieved by the fact that to remove mineral deposits, a composition containing hydrochloric acid and a soluble corrosion inhibitor is used, but unlike the prototype, the tool additionally contains glyoxalic and glycolic acids, glycolaldehyde, antifoam and glyoxal as an additional corrosion inhibitor in the following ratio of components, wt.%:

Hydrochloric acid 20-40 Soluble corrosion inhibitor 1-3 Glyoxal 2-10 Glyoxalic acid 0.5-2 Glycolic acid 0.5-2 Glycol Aldehyde 0.5-2 Antifoam agent 0.01 Water rest.

The introduction of special organic acids into the composition allows for more efficient dissolution of mineral deposits, due to the formation of chelate complex compounds.

The use of a highly effective inhibiting agent - glyoxal, in addition to the standard corrosion inhibitor, allows the use of more concentrated solutions of hydrochloric acid, thereby significantly increasing the dissolving ability of the product, meeting the requirements for corrosion.

When dissolving scale deposits (calcium and magnesium carbonates), carbon dioxide is released. With large volumes of deposits, intense gas evolution is observed during the dissolution process. To prevent foaming and reduce the efficiency of the process, an antifoam is present in the composition of the product.

The composition contains glyoxal, which is the simplest dialdehyde, and glycoaldehyde. The pronounced biocidal activity of aldehydes gives the developed product disinfecting properties. There, it is achieved not only the removal of deposits, but also the disinfection of the inner surface of the pipes and technological equipment.

The following are examples of specific embodiments of the invention.

Example 1

Preparation of the agent was carried out in a glass chemical reactor with an overhead stirrer with a working volume of 10 l at room temperature. With stirring (250 rpm), the calculated amount of components (water, glycolic acid, glyoxalic acid, catasol 28-3, butanol-1, glyoxal, glycolaldehyde, hydrochloric acid) was successively introduced into the reactor.

The result was a solution containing 31.8% hydrochloric acid, 2.6% soluble corrosion inhibitor (Katasol 28-3), 9.8% glyoxal, 1.8% glyoxalic, 1.8% glycolic acid, 1.2 % glycolaldehyde and 0.01% antifoam (butanol-1).

For testing, pipe sections with mineral deposits were taken. The inner diameter of the pipe is 80 mm. The average lumen diameter in the deposits is 45 mm. Visually observed radial heterogeneity (in structure and color) of the deposits. The elemental composition of sediments from the surface and near-wall sediment plot is shown in table 1.

Chipped sediment samples (m = 2.3 g of deposits of the surface part and m = 2.6 g of deposits of the parietal part) were placed in a solution of the prepared product 1: 1. The time of complete dissolution was 40 minutes

Example 2

The solution was prepared, indicated in example 1. The specified pipe segment with a layer of deposits was placed in a 1 liter beaker filled with a 1: 1 solution of the agent. An intense reaction was observed, accompanied by the release of gaseous products. A pipe segment was kept for 15 hours, then the working solution was replaced with a fresh one. After an additional two hours, complete dissolution of the deposits is observed, without visible signs of corrosion of the pipe surface. The initial mass of the pipe segment with deposits of 366.0 g. After the complete removal of the deposits, the mass was 190.3 g. Thus, deposits were removed, making up 48% of the mass of the pipe. When organizing the cleaning of large volumes of mineral deposits, the circulation of the solution of the agent in a closed loop is organized. The optimal dilution of the agent is established based on the composition and amount of deposits, as well as the composition of the alloy from which the equipment is made.

Example 3

The solution indicated in Example 1 was prepared.

At the normal deposition level, the recommended dilution of the agent is 1: 5. The rods from st. 3 with a diameter of (6.0 ± 0.1) mm and a height of (65.0-70.0) mm were selected as an object for testing to determine the corrosion effect on steel. The primary treatment was carried out with a solution of hydrochloric acid 1% (wt.) To remove oxides from the surface of the samples. The treatment was carried out at room temperature for 60 minutes. After the initial treatment, the bar was kept in hot distilled water for 30 minutes to remove the salts formed from the surface of the samples. After that, the bar was dried with acetone and warm air. The dried bar was weighed on an analytical balance to the nearest 0.001 g. Using a caliper, the dimensions of the bar were measured.

The rod was placed in a beaker with a solution (1: 5) of the agent (80 ml) so that the agent completely covered the rod and kept for 24 hours at room temperature.

After testing, the rod was washed under running water and dried in air. After this, repeated weighing was performed.

The value of corrosion for st.35 was 0.19 g / m ² hours

Example 4

The solution indicated in Example 1 was prepared.

For testing, we took sections of screen tubes of heating surfaces of a TGM-96 gas-oil vertical water-turbine boiler containing inorganic deposits. The chemical composition of deposits on the fire side of the pipe: 62.1% iron oxide, 15.2% copper oxide, 4.5% phosphorus oxide, 2.3% calcium oxide, 2.3% silicon oxide, 11.2% insoluble impurities. The specific pollution was 480 g / m ² . The chemical composition of deposits on the rear side of the pipe: 57.7% iron oxide, 28.2% copper oxide, 4.4% phosphorus oxide, 3.6% calcium oxide, 1.7% silicon oxide, 3.4% insoluble impurities. Specific pollution 200 g / m ² .

Conducted parallel processing of pipe samples with a 5% hydrochloric acid solution and an aqueous solution of the proposed tool (1:10). The test results are presented in table 2.

The table shows that the rate of removal of large volumes of mineral deposits in raster of the proposed product is more than 20 times higher than the rate of removal of deposits with a solution of hydrochloric acid having the same hydrogen index (pH).

Thus, the developed tool, having high efficiency in relation to the removal of inorganic deposits of various compositions, has a reduced level of corrosion exposure.

Table 1 Elemental composition of sediments from various sites Element Mass content,% Sample 1 (deposits of the surface) Sample 2 (deposits of the parietal part) O 52.40 49.91 Mg 16.44 6.23 Sa 13.39 08.21 FROM 10.77 16.59 S 4.18 0.79 Si 0.98 0.49 Fe 0.98 2.80 Na 0.94 0.81 Cl 0.22 0.18 P 0.15 0.17 Al 0.13 0.61 Mn 0.07 0.19 Sr 0.05 0.058 K 0.04 0.03

table 2 The results of comparative tests of the solution of the proposed funds 1:10 and 5% hydrochloric acid solution. Samples The solution of the proposed tool (1:10) A solution of hydrochloric acid (5 wt.%) T, ° C pH Holding time, min The number of removed deposits, g / m ² T, ° C pH Holding time, min The number of removed deposits, g / m ² The fire side of the boiler pipe 60 0.38 2 477.47 40 0.40 40 434.0 The back side of the boiler pipe 60 0.38 2 171.3 40 0.40 40 200,0

Claims (1)

A tool for removing rust, scale and other mineral deposits from metal surfaces containing hydrochloric acid and a soluble corrosion inhibitor, characterized in that it additionally contains glyoxalic and glycolic acids, glycolaldehyde, antifoam and glyoxal as an additional corrosion inhibitor in the following ratio of components, wt.%:
hydrochloric acid 20-40 soluble corrosion inhibitor 1-3 glyoxal 2-10 glyoxalic acid 0.5-2 glycolic acid 0.5-2 glycolaldehyde 0.5-2 antifoam 0.01 water rest