MXPA97005452A - Improved organic composition inhibitor of corrosion, incrustation and dispersion for the water of enfriamie systems - Google Patents

Abstract

The present invention relates to: The present invention relates to a water soluble formulation, which allows to maintain an adequate control of the scale in cooling systems with high content of silica and phosphates, an adequate dispersion of solids and bacteriological control, as well as of corrosion in heat exchange equipment, showing high efficiency in each of the mentioned aspects. Furthermore, it does not increase the contamination by heavy metals in the effluents of refineries and chemical plants since it is a product of organic type totally biodegradab

Description

IMPROVED ORGANIC COMPOSITION INHIBITOR OF CORROSION, INCRUSTATION AND DISPERSION FOR THE WATER OF SYSTEMS OF COOLING DESCRIPTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a water soluble formulation, which allows to maintain an adequate control of the incrustation in systems of cooling with high content of silica and phosphates, an adequate dispersion of solids and bacteriological control, as well as corrosion in the equipment of heat exchange, showing high efficiency in each of the aspects mentioned. In addition, metal pollution does not increase heavy in the effluents of refineries and chemical plants as it is a product of organic type totally biodegradable.

BACKGROUND OF THE INVENTION The water used in the cooling systems contains dissolved salts in the form of ions such as calcium, magnesium, sodium, potassium, bicarbonates, carbonates, phosphates, silicates, etc. The solubility of these salts is modified by different factors such as: concentration, pH and temperature; as well as the inclusion of external ions that form insoluble compounds.

When the solubility of the salts present in the water is exceeded by some of the mentioned factors, they preferentially precipitate on the heat transfer surfaces, forming incrustations that interfere in the flow of water, facilitate corrosion and bacterial growth, and also reduce the transfer of heat of these equipments which means a big problem since the energy requirements are increased altering the maintenance costs when a greater number of backwashes and stops for cleaning are required.

On the other hand, corrosion in heat exchangers and pipes significantly reduces the useful life of the equipment by raising maintenance costs and unscheduled shutdowns in production.

CORROSION CONTROL.

For the control of this phenomenon caused by water chemistry, the presence of dissolved oxygen in the recirculating water, as well as by the presence of other pollutants coming from the production processes such as: ac. sulfhídrico, hydrocarbons, ammonia, etc., have been used various compounds based on chromium and zinc, which showed a satisfactory behavior in this application, however the frequent use of these products has caused pollution problems in the effluents of rivers and lagoons , for which the elimination of chromium compounds has been recommended and the consumption of zinc-based compounds has been restricted, concentrating in this case the concentration to values lower than 2.4 ppm in the effluents of refineries and chemical plants.

CONTROL OF INCRUSTATION.

To avoid the formation of deposits of encrusting salts of low solubility, chelate-type compounds such as ac have been used. ethylene diamine tetraacetic, ac. triacetic nitrile and its salts that favor the solubilization of calcium and magnesium compounds; likewise to reduce the tendency to crystallization and deposit formation of these compounds, various compounds have also been used, such as ac. amino trimethylene phosphoric acid, hydroxyethylidene diphosphonic acid and polymers of low and medium molecular weight based on ac. acrylic and acrylamide.

CONTROL OF ENSUCIAMIENTO.

The presence of dissolved salts, organic matter and various contaminants in the water used in the cooling systems, cause the gradual formation of hard and adherent bacteriological deposits mainly on the metal surfaces of heat transfer in the exchangers, reducing the efficiency of these and causing severe problems of clogging and fouling.

To keep under control the formation of deposits of organic and inorganic materials such as clays, muds and silts, natural polymeric materials such as tannins and lignin derivatives (lignosulfonates) have been used mainly; however, these mentioned compounds have as their main disadvantage their high susceptibility to chemical or biological degradation, which further reduces their efficiency. Currently, nonionic biodispersants are used that disperse bacteriological deposits and reinforce the action of biocides.

MICROBIOLOGIC CONTROL.

Due to the high degree of pollution of the recirculation water in the cooling towers, the growth of various microorganisms such as bacteria, algae, fungi, yeasts, etc., which promote the formation of deposits of organic material on the heat exchange surfaces and connection lines, as well as in specific cases, the corrosion below these deposits in the form of pitting (pitting) as those that occur in the case of reducing sulphate bacteria.

To prevent the growth of the aforementioned microorganisms, compounds such as chlorine have been used, in combination with brominated biocides, quaternary ammonium salts and other organic compounds that have limited efficiencies under certain conditions, so that in some cases specific biocides are required. such is the case of aldehyde-type oxidant biocides that keep microbiological growth under control.

The present invention is an improvement of the multifunctional corrosion inhibiting, scaling and dispersion composition for water in cooling towers, which was filed on July 26, 1995, and has File No. 953234, which is owned by the same holder.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a package of chemicals for cooling water treatment that allows to maintain an added control of corrosion and scaling in systems with high content of silica and phosphate as well as the dispersion of solids with good technical and economic advantages. without affecting the ecological environment with heavy metals.

The composition object of the present invention has a highly satisfactory behavior for the control of the typical problems that occur in cooling systems with high concentrations of silica and phosphates.

The product IMP-TE-504 with which the present invention is identified, carries in its formulation two organic corrosion inhibitors of the phosphonocarboxylic and triazole types. With the combined effect of these products at a continuous dosage between 20-60 ppm it is possible to maintain the corrosion rates in the carbon steel equipment in values lower than 5 mpa and lower than 1 mpa for those made of copper and copper alloys . Due to the organic nature of these components, the IMP-TE-504 product does not contribute heavy metals to the environment such as zinc and chromium constituting an ecological advantage and complying with the specifications established by the Ministry of the Environment.

For the dispersion of solids and the control of the scale of salts on the metal surfaces, the formulation object of the present invention carries a mixture of two phosphonic derivatives, this effect being reinforced with a mixture of a copolymer with a molecular weight of 2000 to 3000. upm and a terpolymer of molecular weight from 3500 to 5000 upm.

With this, efficiencies of inhibition to calcium carbonate incrustation greater than 95%, greater than 90% for silica and for phosphates greater than 80% in cooling systems with high silica and phosphate contents are obtained.

The non-ionic biodispersant that is applied increases the penetrating power of chlorine, reinforcing its biocidal action and dispersing bacteriological deposits in cooling systems.

To maintain microbiological control a non-oxidizing aldehyde-type biocide is used that inhibits the growth of bacteria, algae, fungi and yeasts.

It is therefore one of the objects of the present invention to provide a water soluble composition which satisfactorily inhibits fouling, corrosion, fouling and biological growth in cooling water systems with high concentrations of silica and phosphate with the characteristic of being a completely biodegradable product that does not contain heavy metals.

Still another object of the present invention is that the consumption of water in the cooling towers is saved up to 40% since a greater number of concentration cycles are achieved without incrustation and corrosion problems.

From the ecological point of view, the water coming from the purges in the cooling towers where this product is applied, will not contain heavy metals since the product IMP-TE-504 has a totally organic chemical composition.

The composition of the present invention is presented in a liquid state, of amber color with a pungent odor, with the following percentages: Component% Weight Phosphonocarboxylic compound 5-50 Triazole group compound 5-10 Copolymer (2000-3000 upm) 10-30 Terpolymer (3500-5000 upm) 10-30 Phosphonate compounds 5-40 Amine 2-5 Demineralized water 10-30 Hydroxide potassium 20-30 The phosphonocarboxylic compound present in the invention promotes the formation of a protective film, with thickness of several molecules, on the metal surfaces, which constitutes a mechanical and electrochemical barrier that passivates the metal against corrosive attack. This film has a high thermal stability and oxidation and is not easily removable.

The phosphonocarboxylic active component of the present invention has the formula 0 R OH Where: R = OH or NH3 The mixture of low molecular weight polymers present in the composition object of the invention work by dispersing the particles that are in solution, inhibiting the precipitation of calcium carbonate and stabilizing the calcium phosphonate.

The phosphonated active component present in this invention has the following structural chemical formula.

OR CH2 - C - OH 0 I HO ^ || P - 0 - c - C-C HO II CH2 0 CH2 - C - OH OH The usefulness of this compound is due to the fact that it is an extremely effective stabilizer for aqueous solutions supersaturated, especially with calcium carbonate and silica, but also with calcium sulphate and other salts or hydroxides which are difficult to dissolve.

The mechanism of action of this inhibitor supposes an adsorption thereof in the growth points of the crystals.

Another of the phosphonated compounds present in the invention has the following chemical formula.

HO OH OH I I I HO - P - C - P - OH II I II O CH, O This compound has properties as a sequestrant manifesting in a ability to form metal ion complexes at concentrations stoichiometric, also has properties as a dispersant of materials solids and inhibition to precipitation, as well as high thermal stability due to its resistance to decomposition in aqueous solutions in conditions of high temperature and extreme conditions of pH EXAMPLES EXAMPLE 1 In a 1-liter glass container fitted with a cooling jacket and mechanical stirring, 200 g of demineralized water, 1 10 g of the type were charged phosphonocarboxylic acid, 100 g of a phosphonic acid compound, 1 00 g of low molecular weight copolymer and 100 g terpolymer (3500-500 upm). TO Then 20 g of amine is added very slowly (exothermic reaction) and with vapor release), it is cooled and 70 g of a Phosphonated compound of molecular weight 300, the pH is adjusted to 1 1 .0 with 210 g of 50% potash and finally 90 g of a compound of type are added triazole A product with the following characteristics was obtained: Appearance Liquid Amber.

Specific gravity, at 20/4 ° C 1 .1937 Brookfield viscosity, cPs at 20 ° C 34.3 APHA color 24 pH of the 1% solution 1 1 .0 EXAMPLE 2 In a 1-liter glass container fitted with a cooling jacket and mechanical stirring, 250 g of demineralized water, 100 g of type phosphonocarboxylic acid, 100 g of a phosphonic acid compound, 1 50 g of a low molecular weight polymer and 100 g of terpolymer (3500-5000 upm). TO Then 20 g of amine is added very slowly (exothermic reaction) and with vapor release), it is cooled and 80 g of a Phosphonated compound of molecular weight 300, the pH is adjusted to 1 0 with 200 g of 50% potash and finally 50 g of a compound of type are added triazole A product with the following characteristics was obtained: Appearance Yellow liquid Amber.

Specific gravity, at 20/4 ° C 1 .1902 Brookfield viscosity, cPs at 20 ° C 33.1 APHA color 24 pH of the 1% solution 10.0 EXAMPLE 3 In a 1-liter glass container fitted with a cooling jacket and mechanical stirring, 250 g of demineralised water, 1 30 g of the type were charged phosphonocarboxylic acid, 60 g of a phosphonic acid compound, 1 10 g of a low molecular weight copolymer and 1 20 g terpolymer (3500-5000 upm).

Then 25 g of amine are added very slowly (reaction exothermic and with vapor release), cooled and added 60 g of a phosphonate compound of molecular weight 270, the pH is adjusted to 1 0.5 with 205 g of potassium 50% and finally 40 g of a compound of triazole type.

A product with the following characteristics was obtained Appearance Yellow liquid Amber.

Specific gravity, at 20/4 ° C 1 .2004 Brookfield viscosity, cPs at 20 ° C 32.1 APHA color 23 pH of the 1% solution 10.5 EXAMPLE 4 In this example the results of the laboratory-level evaluation of the formulations reported in examples 1 to 3 are shown 1 .- INHIBITION TO CORROSION.

NACE Method TM-01 -72 (Modified) In this procedure, 300 ml of spare water from the refinery to be studied is measured, in this case from Salamanca, Gto., The selected dosage of inhibitor is added, stirred and kept under heating at 50-60 ° C, controlling the pH to the optimum selected in this particular case 7.2 for a period of 4 hrs. , 30 minutes after the start of the test, a carbon steel specimen is immersed in the solution and the agitation is continued until the test time is reached.

At the end of the test, coupons are removed, inspected and graded in relation to the area in question.

Dosage ppm 50 75 100 Example 1 A A A Example 2 A A A Example 3 A A A A = Absence of corrosion. 2. - INHIBITION TO THE PRECIPITATION OF CaCO3, SiO2 AND Ca3 (PO4) 2 Method IMP-PE-ll-1 In this procedure, 500 ml of spare water from the refinery is measured study, in this case that of Salamanca, Gto., the dosage is added selected from the inhibitor, is stirred and the sample is evaporated at a temperature of 60-70 ° C maintaining the optimum pH value, which for this case is 7.2 until reaching the volume corresponding to 3 or 5 concentration cycles as appropriate.

To the concentrated samples calcium is determined by titration with EDTA, silica and phosphates by spectrophotometry and the results are compared with the respective theoretical values.

RESULTS Efficiency to inhibition for CaCO3,% Dosage, ppm 40 60 SO Example 1 74 80 87 Example 2 82 90 93 Example 3 87 93 98 Efficiency to inhibition for SiO2% Dosage, ppm 40 60 80 Example 1 68 70 75 Example 2 70 76 82 Example 3 87 89 92 Efficiency to inhibition for PO4,% Dosage, ppm 40 60 80 Example 1 55 57 59 Example 2 63 69 72 Example 3 79 81 83 It is observed that example 3 has a higher efficiency of inhibition to the precipitation of CaCO3, SiO2 and Ca3 (PO) 2.

EXAMPLE 5 The IMP-TE-504 product was evaluated in pilot cooling tower water.

The test conditions were the following: 1 .- Water containing the characteristics that are listed below: (ppm as CaCO3) Total hardness 140 Calcium hardness 108 Magnesium hardness 32 Alkalinity 264 Silica 162 Copper 0.02 Iron 0.05 Chlorides 160 Turbidity 7 FTU Suspended solids. 10 Total dissolved solids 949 pH 6.81 Plate count 500,000 Bact / ml Reducing sulphate bacteria 24 NM P / 100 ml 2.- Operating conditions.

• Test time 15 days. • Delivery temperature 30 ° C • Return temperature 40 ° C • System pH 7.2. 7.6 • Flow 3 gallons / minute • Speed 3 ft / sec.

Results obtained. 3.2 concentration cycles were achieved in recirculating water with a corrosive stability index of 6.6 to 6.9 and the velocities of corrosion that are indicated below: Admiralty 0.07 mpa Carbon steel 1 .26 mpa The characteristics of the water after 3.2 cycles of concentration were the that are listed below. (ppm as CaCO3) Total Hardness 430 Calcium Hardness 324 Magnesium Hardness 106 Chlorides 496 Alkalinity 122 Silica 503 Turbidity 25 Total Dissolved Solids 2124 pH 7.5 Counts Count 1000 Bact / ml Reducing sulphate bacteria 4 NM P / 100 ml stability index 6.8 The results obtained at the pilot plant level verify the results obtained at the laboratory level, which indicates that the formulation reported in the example 3 presents a satisfactory behavior to inhibit the incrustation, corrosion and dispersion to keep the solids in suspension present in the system.

It is also observed that due to the effect of the biodispersant reinforced by the effect of the microbiocide is achieved maintaining an adequate growth control microbiological.

A total bacterial count of less than 300,000 col / ml and an account is maintained for reducing sulphate bacteria less than 8 col / ml.

Claims (7)

NOVELTIES OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the contents of the following clauses are claimed from our property:

1 . An improved organic composition inhibiting corrosion, scaling and dispersion for cooling system water characterized in that it contains from 5 to 50% by weight of a corrosion inhibitor of the phosphonocarboxylic type and of the triazole type, from 10 to 30% in weight of a copolymer-terpolymer mixture (2000-5000 upm), from 5 to 40% by weight of phosphonated compounds, from 2 to 5% of amine, from 20 to 30% of potash and up to 30 % of demineralized water.

2. An improved composition, according to clause 1, characterized in that it inhibits corrosion, fouling, fouling and biological growth in cooling waters with high concentrations of silica and phosphates.

3. An improved composition according to clauses 1 and 2, characterized in that, due to its organic nature, it does not contain heavy metals and therefore does not contribute to increasing the concentration thereof in aqueous effluents of chemical plants and refineries.

4. An improved composition according to clauses 1 to 3, characterized in that it allows to increase up to 3.2 times the concentration of solids in cooling water, with high silica content, thus contributing to decrease the requirements for replacement water in these equipment.

5. An improved composition according to clauses 1 to 4, characterized in that it has high fouling inhibition efficiency even in cooling systems whose recirculation waters contain high concentrations of calcium, magnesium, silica and phosphate salts.

6. An improved composition according to clauses 1 to 5, characterized in that it presents a high efficiency of dispersion of solids in cooling systems, which allows to reduce the fouling in the tubes of the heat exchangers and consequently to reduce the operation costs by concept of cleaning and maintenance of these equipment.

7. An improved composition according to clauses 1 to 6, characterized in that it allows microbial growth to be kept under control in cooling systems waters, which in turn allows to significantly reduce fouling and corrosion, which occurs below the deposits of organic material in heat exchangers. An improved composition according to clauses 1 to 7, characterized in that it keeps under control the corrosion in copper pipes and their alloys, as well as other carbon steel components of the heat exchangers in the cooling systems.