MXPA03010844A - Chemical composition for the treatment of water with low content of calcium and phosphate salts for cooling systems. - Google Patents

Abstract

The present invention describes a novel multifunctional composition of chemical products for the treatment of municipal and industrial waste waters used in the cooling towers of the Gral. Lazaro Cardenas Refinery in Minatitlan Veracruz, the spare water used in said towers has a low content of calcium salts and calcium carbonate, by which it is possible to maintain under control problems of corrosion, scale, soiling, and sludge formation, as well as dispersion of high concentrations of iron contained in the treated municipal and industrial water resulting from the waste waters treating plant "PTAR". Moreover, said invention permits the operation of high concentration cycles, thereby saving the spare water resource that is supplied to the cooling towers and achieving huge technical, economical and ecological advantages.

Description

"CHEMICAL COMPOSITION FOR THE TREATMENT OF WATER FOR COOLING SYSTEMS WITH LOW CONTENT OF PHOSPHATE AND CALCIUM SALTS ".

D E S C R I P C I O N TECHNICAL FIELD OF THE INVENTION The present invention relates to a composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, the formulation is totally soluble in water and has a high efficiency for the chemical treatment of municipal and industrial wastewater of Cooling towers with low content of salts such as calcium phosphate, which allows to work at high concentration cycles and maintain an adequate control of the generalized corrosion, by pitting, incrustation and dispersion of high concentrations of iron present in treated wastewater, used as spare water for cooling in the heat exchange equipment of the oil industry processes.

BACKGROUND OF THE INVENTION The chemical composition is a multifunctional formulation based on existing multifunctional formulations such as IMP-TE-501, IMP-TE-508 and I P-TE-510. It is worth mentioning that these formulations, at the time, were designed for the treatment of spare water coming from a dam or river, but at present the quality of water available; they are treated black waters which, due to their origin, contain high amounts of sulfur, ammonia nitrogen and heavy metals such as iron, forming ferrous oxides, causing adverse conditions with respect to pitting corrosion rates. (localized corrosion) Therefore there is a need to develop a new improved multifunctional formulation containing a mixture of low molecular weight polymers, these polymers are based on "polyphosphine", differentiate it from the formulations IMP-TE-501, IMP- TE-508 and IMP-TE 510, basically lies in the content of the polymers, since these formulations contain a polymer that, in turn, with the type of spare water that was received in the cooling towers, worked properly and not currently, since the quality of the spare water, at present are very different, so this formulation IMP-TE-501-ZI, object of the present invention is composed of two inhibitors of inorganic base corrosion, useful to solve the problems that are present day in the cooling systems of the oil industry.

The municipal and industrial water used in the cooling towers also contains a wide range of cations, such as: calcium, magnesium, sodium, potassium, and various anions such as carbonates, bicarbonates, phosphates, silicates, etc. When these anions are combined with the cations in concentrations where these limits exceed the solubility of their reaction products, precipitating in the form of complexes difficult to remove. The solubility of the components present varies for the following reasons: concentration of the salts, changes in pH and temperature of operation of the processes; as well as by the introduction of additional ions that form insoluble compounds with the ions already present in the solution.

These reaction products precipitate on the metal surfaces of cooling systems, forming deposits, whose accumulation prevents effective heat transfer, interferes with water flow, facilitates corrosive processes and bacterial growth. This represents a serious problem in the systems of the cooling towers, since the stoppages are increased by mechanical cleaning and removal of deposits adhered to the metal surfaces of the process equipment.

Likewise, corrosion in heat exchange equipment and interconnection lines increases operating costs due to stoppages and maintenance, which significantly reduces the useful life of the aforementioned equipment.

For the control of corrosion, incrustation and dispersion of inorganic and organic materials the following products have been previously used: CORROSION CONTROL. For the control of this phenomenon caused by the presence of dissolved oxygen in the recirculating water of the cooling systems, as well as by the presence of other pollutants coming from the main process such as: hydrogen sulfide, hydrocarbons, ammonia, nitrogenous compounds, etc. ., have been used various compounds based on chromates, which showed a satisfactory behavior in this application, however the frequent use of these products has caused pollution problems in the receiving bodies such as: rivers, lagoons and dams so has recommended the elimination of chromium-based compounds and restricted the consumption of zinc-based compounds, in this case limiting the concentration to values lower than 20 ppm. in the effluents of refineries and petrochemical plants throughout the country.

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

CONTROL OF ENSUCIAMIENTO. The presence of dissolved salts, organic matter and various pollutants in the water used in the cooling systems, cause the gradual formation of hard and adherent organic and inorganic deposits mainly on the metallic surfaces of heat exchange equipment, reducing the efficiency of these and causing severe problems of clogging, corrosion and fouling.

To keep under control the formation of deposits of organic and inorganic materials such as: clays and muds, natural polymeric materials, such as tannins and lignin derivatives (lignosulfonates), have been used mainly; however, these mentioned compounds have as their main drawback their high susceptibility to chemical or biological degradation, which further reduces their efficiency. Currently, nonionic biodispersants are used that keep the organic matter in suspension and reinforce the action of the oxidizing and non-oxidizing biocides in the cooling water recirculation systems.

DETAILED DESCRIPTION OF THE INVENTION The present invention refers to a multifunctional composition of chemical products that we will call "Semi-Organic" for the treatment of municipal and industrial wastewater for cooling use, with low content of salts such as phosphate and calcium carbonate, in the water Replacement in cooling towers, through which it is possible to keep under control the problems of generalized corrosion, by pitting, incrustation, dispersion, sludge formation, allowing to obtain a high efficiency and extensive technical, economic and ecological advantages in the industry. hydrocarbons.

The novel composition, object of the present invention presents a highly satisfactory behavior for the control of problems of the different types of general corrosion, pitting, incrustation and fouling that generally develop in cooling systems with low content of salts such as phosphate and carbonate of calcium, in the spare water in cooling towers, from the municipal and industrial wastewater treatment plant.

The formulation or multifunctional product IMP-TE-501-ZI, object of the present invention, is composed of two corrosion inhibitors: one of organic phosphonate hydroxyphosphonate and another inorganic of zinc salts, in addition to dispersants of calcium salts such as copolymers high efficiency polyphenol carboxylic base, With the continuous use of this multifunctional product used at dosages in the range of 70-150 ppm, it is possible to keep under control the corrosion rates for the parts consisting of white metals such as carbon steel and metals yellows, such as: copper and copper alloys; less than 5 mpa (thousandths of an inch per year) for carbon steel and less than 0.5 mpa for admiralty. It presents additionally as an ecological advantage that does not contain chromium, thus complying with the regulations and specifications established by the Ministry of the Environment, without the above resulting in a lower efficiency in terms of protection against pitting and generalized corrosion. .

For the control of the formation of encrusting salts on the metallic surfaces of the cooling systems, the formulation object of the present invention contains a mixture of low molecular weight copolymers (2000-3000), specific for municipal and industrial waters that are used as spare parts in cooling towers. The copolymers, one specific for calcium and the other for phosphates, obtaining efficiencies of inhibition to the incrustation in calcium and phosphate salts, such as calcium carbonate, above 95 and 98% respectively, in industrial tests.

Other objects of the present invention are: 1. - Provide a completely water soluble multifunctional chemical composition that satisfactorily inhibits the scaling of salts present in water, as well as generalized corrosion, pitting, fouling and biological growth in cooling water systems with low salt content. as calcium phosphate and carbonate, from municipal and industrial wastewater treatment plants. 2. It allows the saving in the consumption of spare water to the cooling towers, up to 55%, reaching a greater number of concentration cycles without presenting incrustation, corrosion and fouling problems. 3. In waters that contain low concentration of calcium and phosphates, manages to effectively disperse these materials, preventing their precipitation and thus preventing them from depositing on the metal surfaces of process equipment, reducing fouling in process lines by up to 30% , which allows to avoid unplanned plant shutdowns, continuing with the production programs and having a significant saving by cleaning and maintenance in the heat exchange equipment.

The composition of the present invention IMP-TE-501-Z is presented in the state Liquid, amber, aromatic odor characteristic .with the following composition: COMPONENT% WEIGHT Polyphosphino-carboxylic acid 3-18 l-hydroxyethylidene 1,1-diphosphonic acid (HEDP) 1-24 38% Muriatic acid 3-25 40% zinc nitrate 6-32 phosphoric acid 80% 3-20 Polyphosphine copolymer mixture 3-20 carboxylic acid and acrylic acid acrylamide 40-60 demineralized water The polyphosphino carboxylic acid compound present in this formulation promotes the formation of a protective film on metal surfaces, constituting a mechanical and electrochemical barrier that passivates the metal against the corrosive and incrustante attack, this film possesses high degree of thermal stability and to the oxidation, since it is not easily removed.

Additionally it contains a mixture of copolymer of acrylic acid acrylamide and a phosphino carboxylic copolymer, which act offering a synergistic effect High dispersion efficiency of calcium and phosphate salts present in waters municipal and industrial that are supplied as spare water to the towers Cooling.

E J E M P L O S EXAMPLE 1 In a 1.5 liter glass vessel with cooling jacket and mechanical stirring, 410g were placed. of demineralized water and 200g. of 1-hydroxyethylidene 1,1-diphosphonic acid, obtaining a pH of about 1.2. Subsequently, 110 g were added. of muriatic acid with a purity of 38% and 80 g. of zinc nitrate with a purity of approximately 40%, this mixture has a clear yellowish coloration and no increase in temperature; continue shaking for approximately 20 minutes. Continuing with the agitation, later 30 g were added. of polyphosphino carboxylic acid and 40 g. of 80% phosphoric acid, the mixture obtained here gives us a light brown color, and without an increase in temperature.

Subsequently, a mixture of copolymers of polyphosphino carboxylic acid and acrylic acid acrylamide in an amount of 130 g are added. the final mixture gives a pH of approximately 1.2, without interrupting the mechanical agitation, until a homogeneous mixture is obtained.

The characteristics of the product obtained are the following: Appearance Light brown liquid Specific gravity, 20/4 ° C 1.0- 1.5 Drain temperature, ° C -20 - -43 pH of the 1% solution 1.2 Agitation times and speeds are of vital importance for obtaining the results reported here, so the intervals should be maintained established as well as the order of incorporation of each of the components of the present novel formulation for the treatment of cooling waters. EXAMPLE 2 In a 1.5 liter glass container with cooling jacket and stirring mechanical, 530 g were placed. of demineralized water and 110 g. of 1-hydroxyethylidene 1,1-diphosphonic acid, obtaining a pH of about 1.2. Subsequently, 150 g were added. of muriatic acid with a purity of 38% and 80 g. of zinc nitrate with a purity of approximately 40%, this mixture It has a light yellow coloration and no increase in temperature; continue shaking for approximately 20 minutes. Continuing with the agitation, then 30 g were added. of polyphosphino carboxylic acid and 60 g. of 80% phosphoric acid, the mixture obtained here gives us a brown color clear, and without increasing the temperature.

Subsequently, a mixture of polyphosphino carboxylic copolymers and acrylamide acrylic acid in an amount of 40 g. the final mixture gives us a pH of 1.2 approximately, without interrupting the mechanical agitation, until obtaining a mixture homogeneous The characteristics of the product obtained are the following: Appearance Light brown liquid Specific gravity, 20/4 ° C 1.0- 1.6 Run-off temperature, ° C -20 - -49 pH of the 1% solution 1.2 EXAMPLE 3 In a 1.5 liter glass container with cooling jacket and stirring mechanical, 600 g were placed. of demineralized water and 90g. of 1-hydroxyethylidene 1,1-diphosphonic acid, obtaining a pH of about 1.2.

Subsequently, 70 g were added. of muriatic acid with a purity of 38% and 60 g. of zinc nitrate with a purity of approximately 40%, this mixture presents a clear yellowish coloration, no increase in the temperature of the mixture, continue stirring for a period of approximately 20 minutes.

Without interrupting the agitation, later 70 g were added. of polyphosphine acid carboxylic and 50 g. of 80% phosphoric acid, the mixture so far obtained gives us a light brown color, and without temperature increase, subsequently add a mixture of polyphosphino carboxylic acid and acrylic acid copolymers acrylamide in an amount of 60 g. the final mixture gives us a pH of 1.2 approximately, without interrupting the mechanical agitation, until obtaining a mixture homogeneous A final product was obtained with the following characteristics: Appearance Light brown liquid Specific gravity, 20/4 ° C 1.0- 1.56 Drain temperature, ° C -20 - -47 pH of the 1% solution 1.2 EXAMPLE 4 In a 1.5 liter glass container with cooling jacket and stirring mechanical, 560 g were placed. of demineralized water and 148g. of 1-hydroxyethylidene 1,1-diphosphonic acid, obtaining a pH of about 1.2, Subsequently, 112 g were added. of muriatic acid with a purity of 38% and 70 g. of zinc nitrate with a purity of approximately 40%, this mixture has a light yellowish coloration, no increase of mix temperature, continue stirring for an approximate time span 20 minutes.

Continuing with the agitation, later 30 g were added. of polyphosphine acid carboxyl and 40 g. of 80% phosphoric acid, the mixture obtained here gives us a light brown color and no increase in temperature, subsequently add a mixture of polyphosphino carboxylic acid and acrylic acid copolymers acrylamide in an amount of 40 g. the final mixture gives us a pH of 1.2 approximately, without interrupting the mechanical agitation, until obtaining a mixture homogeneous The characteristics of the product obtained are the following: Appearance Light brown liquid Specific gravity, 20/4 ° C 1.0- 1.5 Drain temperature, ° C -20 - -43 pH of the 1% solution 1.2 EXAMPLE 5 These examples of preparations were evaluated to check their efficiency at precipitation of salts of (CaCO3), using the IMP-PE-II-I method.

This method described here is used for the quantification of efficiency at the incrustation in calcium salts mainly. For the application of this method, They measured 500 mi. of water from the place of origin, where this formulation will be applied multifunctional zinc-based.

It is dosed at a rate of 30-40 ppm. of the novel formulation, it is homogenized and maintains at a temperature of the order of (70 ° C) with continuous agitation, evaporating the sufficient quantity such that a concentration of 2.5 and 5. 5 cycles of concentration, it is worth mentioning that this test is controlled at a pH similar to the operation of cooling systems, where it will be applied This new multifunctional formulation, object of this invention.

The sample volume of 50 milliliters is prepared, to later determine the amount of calcium per titration, using for it the (EDTA) ethylene diamine tetra acetic, the results obtained, at no time should be less than 90%, for dissolved salts of CaC03 (calcium carbonate).

Results Efficiency at scale inhibition% Dosage ppm 40 60 80 Example 1 16 20 31 Example 2 17 19 24 Example 3 86 91 95 Example 4 78 86 93 The composition of Example 3 is the one that gives us the best results of inhibition to the incrustation, where the 40, 60 and 80 ppm dosages were applied, respectively.

Method NACE -ST-03-74 For this test, equal volumes of test solutions a and b are mixed in specific bottles for this test, then dosed at a rate of 60 -80 ppm. of the formulation and remain in constant warming for a period of 72 hours at a temperature of approximately 71 ° C.

A 50 milliliter aliquot is then taken from the center of the bottle and determines calcium by titration with the use of EDTA (ethylene diamine tetra acetic), the result obtained may not be less than 90% of the efficiency.

The composition of the brines used in the test are: a) .- 11.1 g / l of CaCl2. 2H20 7.5 g / l of NaCl b) .- 7.5 g / l NaCI 10.66 g / l of NaS04 Results Efficiency of inhibition to incrustation% Dosage 40 60 80 Example 1 12 16 15 Example 2 11 13 12 Example 3 91 94 96 Example 4 87 92 95 APPLICATION OF THE COMPOSITION The chemical composition was tested under the conditions of Example 5, since its efficiency must be verified in real pH ranges such as those of the Field cooling, likewise temperatures of the order of 70 ° C, are very significant, considering that the thermal exchange equipment of the cooling systems, handle this temperature range.

As regards the concentration cycles, it is of vital importance to test the chemical composition object of this invention; to have the knowledge of up what range can I concentrate the recirculation water of the cooling systems, without fouling or embedding problems, caused by the salts naturally dissolved in the water that is received as a replacement in the towers of cooling.

This multifunctional formulation based on zinc, was tested at an industrial level, dosed at a rate of 80-120 ppm. in a large-scale cooling system (industrial) obtaining excellent results in terms of inhibition efficiencies to the incrustation, in calcium salts of the order of 93%. Regarding corrosion, maximum values of 2 mpa were obtained, both instantaneous and with corrosometer, and also in carbon steel coupons, remaining below the specified for this metal, for this parameter (5 mpa max), checking in this industrial scale that this novel formulation, object of this invention, is of last generation unique in its type; also offering excellent dispersion of dissolved salts in the treated wastewater, which are provided as spare water in the cooling systems of the national refining system.

Claims (8)

NOVELTY OF THE INVENTION Once the present invention is described, it is considered as a novelty by its components, therefore the content of the following clauses is claimed as property:

1. - A chemical composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, characterized in that it contains in its formulation 3-18% by weight of polyphosphino carboxylic acid, of 3-25% by weight of acid 38% muriatic, 6-32% by weight of 40% zinc nitrate, 3-20% of 80% phosphoric acid, has a pH value of 1.2, of 3- 20% by weight of the mixture of organic copolymers of acrylic acid acrylamide and polyphosphino carboxylic copolymer, of 1-24% by weight of 1-hydroxyethylidene 1,1-diphosphonic acid (HEDP) and 40-60% by weight of demineralized water.

2. - A chemical composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, according to clause 1 characterized because it is able to inhibit corrosion, scaling, fouling in municipal and industrial waters for cooling towers of the process equipment of the hydrocarbon industry.

3. - A chemical composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, according to clauses 1 and 2 characterized because its "semi-organic" nature is highly efficient to inhibit corrosion in white metals such as Carbon steel and yellow metals such as admiralty, does not exceed the limits of currently permitted heavy metals concentrations of 20 ppm in the aqueous effluents from refinery process plants.

4. - A chemical composition for water treatment for cooling systems with low content of phosphate and calcium salts, according to clause 1 to 3, characterized in that it allows to increase up to 5 times the concentration of dissolved salts in municipal and industrial wastewater. the cooling systems, thus contributing to a saving of spare water in the process equipment and consequently a reduction in the electric power consumption of the pumping equipment of the spare water supplied to the cooling towers.

5. - A chemical composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, according to clause 1 to 4, characterized in that it exhibits high efficiency of inhibition to the incrustation, by salts of calcium and phosphate, in systems of cooling even in cooling systems whose municipal and industrial wastewater recirculation in cooling towers.

6. - A chemical composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, according to clause 1 to 5, characterized because it exhibits a high efficiency of dispersion of solids in cooling systems that use in its recirculation municipal and industrial wastewater with low salt content such as calcium phosphate and carbonate, which allows to reduce fouling in heat exchange exchanger tubes and consequently reduce operating costs for cleaning and maintenance of wastewater equipment. process.

7. - A chemical composition for the treatment of water for cooling systems with low content of phosphate and calcium salts, according to clause 1 to 6, characterized in that it allows to keep in control the bacteriological growth in water of cooling systems with high content of salts of phosphate and calcium carbonate, allowing significantly reduce corrosion and fouling, which occurs under the deposits of organic material in heat exchangers that use cooling systems.

8. - A chemical composition for water treatment for cooling systems with low content of phosphate and calcium salts, according to clause 1 to 7, characterized in that it keeps corrosion control in copper pipes and their alloys, as well as other components of carbon steel from heat exchangers of cooling systems of hydrocarbon cooling plants.