CS246448B1 - Corrosion inhibiting and dispersant-sequestering composition for water cooling circuits - Google Patents

Abstract

The solution belongs to the field of metal protection against corrosion and solves the anti-corrosion protection of steel and other metals in heat exchange systems with an aqueous cooling medium. The composition with corrosion inhibiting and dispersing-sequestering effect for aqueous cooling circuits according to the solution contains 1 to 20 parts by weight of ethane-1-hydroxy-1,1-diphosphonic acid, 2 to 10 parts by weight of 2-mercaptobenzothiazole, 1 to 15 parts by weight of an alkaline saponified copolymer of acrylic acid with acrylonitrile, 1 to 15 parts by weight of sodium hydroxide and 40 to 80 parts by weight of water. The effectiveness of the composition can be further increased by adding 0.1 to 10 parts by weight of triethanolamine phosphate. The composition with corrosion inhibiting and dispersing-sequestering effect for water cooling circuits is continuously maintained in water heat exchange media at a concentration of 20 to 100 g. m-3.

Description

The invention relates to a composition with a corrosion-inhibiting and dispersing-sequestering effect for the progressive treatment of the heat exchange environment of steel systems comprising also materials of the medium, aluminum, zinc and their alloys in circulating smoothing circuits.

The influence of water heat exchange medium on steel systems leads to corrosion of steel and other metals. The corrosion proceeds evenly, but due to the formation of suspended solids, such as insoluble salts, mainly calcium carbonate, dust, clay, sand, corrosion products, biomass, it is uneven in character, most often in the form of hole corrosion, but worsens the hydraulic resistance of water flow in pipelines thereby increasing the additional thermal resistance on the heat exchange surfaces.

Corrosion inhibitors based on chromates, nitrites, silicates, phosphates, molybdates and zinc salts are added to these systems to prevent the corrosion effect of aqueous heat exchange media on steel systems.

These compositions are capable of suppressing corrosion of steel to a large extent, but not of media, aluminum and zinc and their alloys, nor do they suppress the build-up of sediment layers and therefore cannot prevent the increase of hydraulic and thermal resistance and hence uneven forms of corrosion.

In addition, some known corrosion inhibitors are also harmful to health, for example chromates, nitrites, and at the same time do not safely suppress the corrosion of the steel unless their necessary minimum concentration in the aqueous medium is maintained.

Therefore, dispersing additives such as cellulose and its derivatives, polyacrylates, polyacrylamides and the latest synthetic polymers such as e.g. copolymer of ethylene oxide and propylene oxide and others.

Sequestering agents are known for suppressing the formation of solid deposits which, by forming non-stoichiometric complexes, prevent the formation of insoluble salts and the formation of their layers on the steel surfaces. Inhibitors of these deposits primarily include polyphosphates, natural polymers such as lignin and tannin.

The most widely used polyphosphate programs hitherto have the disadvantage that in systems with longer residence times, high operating temperatures and higher pH values, reversibility occurs (retrogradation of the polyphosphate to orthophosphate, resulting in sticky calcium orthophosphate deposits).

The drawbacks of the prior art in this field are largely overcome by compositions having a corrosion-inhibiting and dispersing-sequestering effect for water cooling circuits according to the invention which outperforms the compositions protected by the following patents:

GB - no. 1,475,049 - protects a composition comprising pyrophosphate, amines, organophosphate, and benztriazole;

GB - no. 1,475,059 - protects a composition comprising ethane-1-hydroxy-1,1-diphosphonic acid, dibutylamino, pyrophosphate, triazole;

US-No. 3,992,318 - protects the composition of polyphosphate, organophosphate, acrylic acid copolymer;

US-No. 4,149,969 - protects the composition of alkali metal molybdate, heavy metals Zn ²⁺ , Mn ²⁺ , Ni ²⁺ , sodium salts of ethane-1-hydroxy-1,1-diphosphonic acid, benztriazole,

2-mercaptobenzothiazole, tolyltriazole;

US-No. 4,172,032 - protects a composition comprising condensed phosphate, phosphated glycerol, azole;

US-No. 4,187,235 - protects the composition in the composition of foisphonomethylamino (hydroxy) propane and sulfonic acids;

US-No. 4,206,075 - protects the composition of a combination of phosphonic acids, Zn ²⁺ salts, chromates, benztriazole, and polyacrylates;

US-No. 4,209,487 - protects the composition of phosphonic acid, azoles, sodium molybdate, 2-mercaptobenzotriazole and chromium salts;

US-No. 4,217,216 - protects the composition comprising acrylic acid polymer, citric acid, phosphonic acid, benztriazole, sulfopolystyrol and sodium molybdate dihydrate;

JA - no. 40 175 - protects the composition of a phosphonic acid derivative, guanidine phosphate;

JA - no. 44 893, 44 894, 44 895, 44 896, 44 897 - protect compositions comprising oxydicarboxylic acid, amine carboxylic acid, and phosphonic acid derivatives at various concentrations.

The present invention consists of:

First

from 1 to 20 wt. parts of ethane-1-hydroxy-1,1-diphosphonic acid;

Second

from 2 to 10 wt. parts of 2-mercaptobenzothiazole;

Third

from 1 to 15 wt. parts of an alkali-saponified acrylic acid-acrylonitrile copolymer;

4th

from 1 to 15 wt. parts of sodium hydroxide;

4 6 4 4 9

5th

from 0.1 to 10 ihmot. parts of triethanolamine phosphate;

6th

from 40 to 80 wt. parts of water.

The present composition is added to an aqueous heat exchange medium at a concentration of 20 to 100 g. m ~ ³ .

This composition, as a multi-component mixture of synthetic organic corrosion inhibitors including specific sediment control agents, provides double corrosion control.

At the anode, this is provided by the action of the azole inhibitor 2-mercaptobenzothiazole, which is a specific inhibitor of Cu, Al, Zn and their alloys, and at the cathode it is provided by ethane-1-hydroxy-1,1-diphosphonic acid, where the cathode corrosion inhibitor also has a strong chelating component that ensures the stability of water hardness at high temperatures (200-250 ° C), long residence times (100 hours) and high pH values (pH-10.5 to 11%, where ethane-1 acid) -hydroxy-1,1-diphosphonic acid under the given conditions is substantially stable, thereby providing a possibility of higher concentration and also helps to remove, together with an anionic dispersant, acrylic acid copolymer with acrylonitrile, iron oxides from the cooling system.

The composition provides sediment control, thereby allowing the cooling water treatment program to operate in neutral and alkaline ranges while providing selective control of calcium carbonate deposits (by adjusting the crystalline lattice structure).

The composition has a self-passivating capability without the need for curing ions. It can also be used in systems where calcium concentrations are insufficient for proper phosphate film formation.

Said mode of operation using said composition at higher densities provides a relatively large reduction in the cost of chemical treatment of the circulating cooling ducts, saving of make-up water and saving the energy required for pumping the aqueous heat exchange medium and for brining it.

The invention and its effects are explained in more detail by means of the following examples.

Example 1

Adjustment using the composition in an amount of 50 g. m ^{3 of} circulating water of 8 wt. parts by weight of ethane-1-hydroxy-1,1-diphosphonic acid, 11 wt. parts by weight of sodium hydroxide, 1.5 wt. 5 parts by weight of an alkali-saponified acrylic acid-acrylonitrile copolymer; parts of 2-mercaptobenzothiazole and the rest of the water, reduced the corrosion of the steel by 92% and the formation of deposits from impurities! and 94% calcium salt:

Example 1 and d 2

Correction using 50g composition. m ^{-3 of} circulating water of 8 wt. parts by weight of ethane-1-hydroxy-1,1-diphosphonic acid, 11 wt. parts by weight of sodium hydroxide, 1.5 wt. 5 parts by weight of an alkali-saponified acrylic acid-acrylonitrile copolymer; parts by weight of 2-mercaptobenzothiazole, 5 wt. parts of triethanolamine phosphate and the rest of the water, reduced corrosion by 96% and reduced the formation of deposits formed from impurities and calcium salts by 96%.

The invention is intended for use in steel systems of aqueous heat exchange environments in the chemical, food, pharmaceutical, metallurgical industries, but mainly in power engineering.

Claims (2)

2 4 6 4 4 8 6 5. parts of triethanolamine phosphate; 6. from 40 to 80 wt. parts of water. The introduced composition is added to the aqueous heat transfer medium at a final rate of 20 to 100 g. m ~ 3. This composition, as a multi-component synthetic biosynthetic inhibitor, including specific control agents, provides double corrosion control. The anode is provided by the action of the azole inhibitor 2-mercaptobenzothiazole, which is a specific inhibitor of the Cu, Al, Zn and their alloys corrosion and is provided on the cathode by ethane-1-hydroxy-1,1-diphosphonic acid, where the phosphonic compound inhibitor as a cathodic corrosion inhibitor also has a strong chelating component that provides water hardness stability at high temperatures (200-250 ° C), residence times (100 hours) and high pH values (pH 10.5). (11) (where ethane-1-hydroxy-1,1-diphosphonic acid is very stable under the given conditions, thus providing the possibility of higher concentration and also helps to remove together with the anion-active dispersant - acrylic acid-acrylonitrile copolymer) , iron oxides of a cooling system The composition provides a deposit control, thereby allowing the cooling water treatment program to operate in neutral and alkaline ranges and at the same time provision exists a selective control ,. uhličitanuvápenatého deposits (by modifying the crystalline lattice structure-Vej). The composition has a self-passivating ability without the need for curing ions. It can also be used in systems where calcium concentrations are inadequate to form a phosphate film. Said method of operating said composition at higher densities provides for a relatively large reduction in the cost of chemical treatment of circulating cooling water, saving additional costs, and saving the energy required for the pumping water heat exchange environment and for refining. The invention and its effects are explained in more detail by the following examples. Example 1 Preparation using a composition of 50 gm 3 circulating water comprising 8 parts by weight of ethane-1-hydroxy-1,1-diphosphonic acid, 11 parts by weight of sodium hydroxide, 1.5 parts by weight of alkali saponified acrylonitrile acrylic acid copolymer, 5 parts by weight of 2-mercapto-benzothiazole and the remainder water, reduced by 94% corrosion of the steel and 94% by settling of impurities and calcium salts: Example 2 Correction using a composition of 50 g m-3 circulating water comprising 8 parts by weight of ethane-1-hydroxy-1,1-di-phosphonic acid, 11 parts by weight of sodium hydroxide, 1.5 parts by weight of alkali-saponified acrylic acid copolymer with acres -lonitrile, 5 parts by weight of 2-mercaptobenzothiazole, 5 parts by weight of trethanolamine phosphate and the remainder water, reduced the corrosion by 96% and reduced the formation of deposits from the impurities and calcium salts by 96%. hot water systems in the chemical, food, pharmaceutical, metallurgical, but mainly energy industries. p R E D Μ E T 1. A composition having a corrosion-inhibiting and dispersing-sequestering effect for aqueous cooling circuits comprising from 1 to 20 wt. of 1-hydroxy-1,1-diphosphonic acid-1-hydroxyethane, 2 to 10 wt. parts of 2-mercaptobenzothiazole, 1 to 15 wt. parts of an alkali-saponified acrylic acid copolymer with acrylonitrile, 1 to 15 wt. % sodium hydroxide and 40 to 80 wt. parts of water. 2. A composition according to claim 1, further comprising from 0.1 to 10 parts by weight of trletanolamine phosphate.