CS231112B1 - Composition with corrosion-inhibiting, dispersing and sequestering effect - Google Patents

Abstract

The invention belongs to the field of metal corrosion protection and solves the corrosion protection of steel heat exchange systems with aqueous cooling medium. The composition having a corrosion-inhibiting, dispersing and sequestering effect for the aqueous heat transfer medium according to the invention comprises from 50 to 90 wt. % of a copolymer of alkylene oxides having from 2 to 5 carbon atoms in the chain, having a molecular weight of from 250 to 5000, for example ethylene oxide with propylene oxide, from 5 to 30 wt. % phosphoric acid compound with alkanolamines having from 2 to 8 carbon atoms in the chain, for example diethanolamine phosphate and from 5 to 20 wt. % of an alkali metal polyphosphate such as sodium hexametaphosphate. Furthermore, the effectiveness of the composition can be increased by 4 by adding 0.5 to 10 wt. % of a phosphated alkylphenol having from 2 to 9 carbon atoms in the chain, for example a nonylphenol, or an ethoxylated amine of 12 to 20 carbon atoms, for example hexdecylamine. The composition is added to the aqueous heat transfer medium at a concentration of 3 to 100 g per m 3.

Description

( ₇₅ / BARTONÍCEK ROBERT ing.CSc., GERMAN SLAUGHTER. Ing.CSc.,

Author of the invention VOŠTA JO doc.ing.CSc., PRAGUE, PAUL δ MILAN ing.CSc.,

ŠEBO TOMÁŠ ing., ŠPACÝR JOSEF ing., PRIEVIDZA,

SMALL CLEMENT ing., SaLA, KULHAVÍ TEOFIL ing.,

PANÁČEK FRANTIŠEK ing.CSc., SLÁDBCKOVÁ ALENA ing.CSc.,

KOSlCA JOSEF ina., PRAGUE, NOVAK LADISLAV ing.CSc .. PRIEVIDZA (54) Corrosion inhibiting, dispersing and sequestering agent

The invention belongs to the field of metal protection against corrosion and solves corrosion protection of steel heat exchange systems with aqueous cooling medium. The composition with corrosion inhibiting, dispersing and sequestering effect for the aqueous heat transfer media according to the invention comprises from 50 to 90 wt.

% of a C 2 -C 5 alkylene oxide copolymer having a molecular weight of 250 to 5,000, for example ethylene oxide with propylene oxide, from 5 to 30 wt. % of a phosphoric acid compound with C 2 -C 8 alkanolamines in the chain, for example diethanolamine phosphate and from 5 to 20 wt. % of an alkali metal polyphosphate, for example sodium hexametaphosphate. The efficacy of the composition can be further enhanced by the addition ^{of 4} of 0.5 to 10 wt. % Phosphated alkylphenol having 2-9 carbon atoms in the chain, e.g., nonylphenol or etoxilova _f Joint amine having 12 to 20 carbon atoms, e.g. hexdecylaminu. The composition is added to the aqueous heat transfer medium at a concentration of 3 to 100 g per m @ 2

231 112

231 112

The present invention relates to a composition having corrosion inhibiting, dispersing and sequestering action for aqueous heat transfer media of steel systems.

The influence of the water heat exchange medium on steel systems leads to corrosion of the steel. The corrosion proceeds evenly, but due to the formation of deposits of suspended solids, such as insoluble salts, especially calcium carbonate CaCO3, dust, clay, sand, corrosion products, biomass, it takes on an uneven character, most often a form of pitting. The deposits not only promote the formation of an uneven form of corrosion, but also worsen the hydraulic resistance of the water flow in the pipelines and increase the additional thermal resistance on the heat shield surfaces.

In order to prevent the corrosion effect of aqueous heat transfer media on steel systems, corrosion inhibitors are added to these media. Steel corrosion inhibitors based on nitrites, chromates, phosphates and zinc salts are known. These compositions are capable of inhibiting the corrosion of steel to a varying extent, but do not suppress the growth of deposit layers and therefore cannot prevent the increase of hydraulic and thermal resistances and thus the formation of uneven forms of corrosion. In addition, some known steel corrosion inhibitors are also harmful to health, such as nitrites and chromates, and at the same time do not safely suppress corrosion of the steel unless their required minimum concentration in the aqueous medium is maintained. Therefore, for suppressing deposits, it is necessary

231 112 use dispersing additives such as lignins, cellulose and its derivatives, polyacrylates and polyacrylamides. Sequestering agents are known for suppressing deposit formation which prevent the formation of insoluble salts and the formation of their layers on the steel surface by forming non-stoichiometric complexes. Such agents are, for example, organophosphoric acids. However, sequestering agents do not prevent corrosion of steel by themselves, but in many cases support it.

The drawbacks of the prior art in this field are largely overcome by the corrosion-inhibiting, dispersing and sequestering composition according to the invention, which comprises from 50 to 90 wt. % of a C 2 -C 3 alkylene oxide copolymer having a molecular weight of 250 and 3000, for example ethylene oxide with propylene oxide, from 5 to 30 wt. % of a phosphoric acid compound with C 2 -C 8 alkanolamines and from 5 to 20 wt. % of alkali metal polyphosphates, for example sodium hexametaphosphate. The efficiency of the composition is further increased by the addition of 0.5 to 10% by weight. % of a phosphated alkylphenol of 2 to 9 carbon atoms in the chain, for example nonylphenol, or an ethoxylated amine of 12 to 20 carbon atoms, for example hexadecylamine.

The composition is added to the aqueous heat transfer medium -3 at a concentration of 3 to 100 g. m.

The composition has the ability to suppress uniform and uneven corrosion of steel, while favorably affecting the corrosion behavior of alloyed steels and other metals. It prevents sedimentation of suspended solids from the environment, such as sludge, clay, sand, dust, or as a result of a corrosion process or other precipitation reaction. At the same time, the composition limits the formation of insoluble

- 3 231 112 calcium and magnesium salts, thus allowing the aqueous heat transfer media to be operated with higher concentrations of these salts. It reduces the formation of deposits of dead biomass and biological growth due to a slightly biocidal effect. This combined effect increases the service life of the steel equipment, extends the cleaning cycles, reduces energy losses, and thus contributes to the energy savings required for pumping and cooling the aqueous heat exchange environment.

The invention and its effects are explained in more detail by way of a description of the following examples:

Example 1

Repair of 1000 m ^ aqueous heat transfer medium in steel systems by adding 25 kg of ethylene oxide-propylene oxide copolymers in a 1: 1 ratio, 15 kg of triethanolamine phosphate and 10 kg of sodium hexametaphosphate reduced steel corrosion by 85% and reduced the formation of organic and calcium salt deposits 70%.

Example 2

Treatment of 5000 η »θ of aqueous heat transfer medium in steel systems by adding 225 kg of ethylene oxide-propylene oxide copolymers in a ratio of 0.4: 0.6, 13 kg of triethanolamine phosphate and 13 kg of sodium tripolyphosphate and 20 kg of hexadecylamine oxyethylated with 20 moles of ethylene oxide steel by 60% and reduced the formation of impurities by 90%.

Example 3

O

Treatment of 1000 λ of aqueous heat transfer medium in steel systems by the addition of a composition of 14 kg of copolymers of ethylene oxide with propylene oxide in a ratio of 0.6: 0.4, 4 kg of monoethanolamine phosphate and 2 kg of sodium hexametaphosphate reduced

231 112 corrosion 80 80 clay and reduced the formation of deposits originating mainly from insoluble calcium salts by 85%.

Example 4 ^of 3

Treatment of 1000 n aqueous heat transfer medium in steel systems by adding 12 kg of ethylene oxide / propylene oxide copolymer in a ratio of 1: 1, 6 kg of tricalcium phosphate and 2 kg of sodium tripolyphosphate reduced the steel corrosion by 80% and reduced the formation of calcium salts. 68% impurities.

Example 5 ^of 3

Treatment of a 2000 m aqueous heat exchange medium in steel systems by adding 100 kg of a 1: 1 ethylene oxide-propylene oxide copolymer, 60 kg diethylamine phosphate, 40 kg sodium hexametaphosphate and 20 kg phosphated nonylphonol reduced the composition by 90% and reduced the formation of impurities and calcium salts by 92%.

For the corrosion evaluation of the steel, a method of determining the weight loss was used to monitor the loss of metal material exposed to the same time treated and untreated cooling water. Deposit formation was determined by determining the weight of the layers on the metal samples and observed deposits in inhibited and uninhibited water. The deposits were chemically analyzed. ·

The foaming was determined by determining the height of the foam produced by shaking 100 ml of treated water in a graduated cylinder for one minute and reading the foam height after minutes. The formulation was found to have low foaming.

The invention is intended for use in steel systems of water-exchange heating mediums in the chemical, food, pharmaceutical and metallurgical industries and in power engineering.

P S E D ME T OF THE INVENTION

Claims (3)

P S E D ME T OF THE INVENTION 231 112 Claims 1. A corrosion-inhibiting, dispersing and sequestering účtnkem _/ characterized in that it comprises from 50 to 90 wt. % copolymers of C 2 -C 3 alkylene oxides having a molecular weight of 250? ** 3000, for example ethylene oxide with propylene oxide, from 5 to 30 wt. % of a phosphoric acid compound with C 2 -C 8 alkanolamines, for example diethanolamine phosphate, and from 5 to 20 wt. % of an alkali metal polyphosphate, for example sodium hexametaphosphate. 2. The device referred to in point 1 _? characterized in that it further comprises from 0.5 to 10 wt. % phosphated alkylphenol of 2 to 9 carbon atoms in the chain, for example nenylphenol. 3. The composition of claim 1, further comprising from 0.5 to 10 wt. % of an ethoxylated amine of 12 to 20 carbon atoms in the chain, for example hexadecylamine.