RU2738662C1 - Preparation for scaling and cleaning of internal surfaces of heat power and process equipment from scaling deposits - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to acidic detergents based on organic acids and can be used in factories where scale is formed on equipment. Described is a preparation for descaling and cleaning of internal surfaces of heat and power and process equipment from scale deposits, comprising: urotropin, thiourea, urea, lactic and citric acids, non-ionic surfactants: triton X-100 and TWEEN-80, methyl red dye-indicator of pH level and water, with the following ratio of components, wt. %: urea 3.5–3.7, lactic acid 7–7.5, citric acid 7–7.5, urotropine 0.3–0.5, thiourea 0.3–0.5, triton X-100 - 1–2, TWEEN-80 - 0.5–1, methyl red 0.1–0.2, water 77.1–80.3.

EFFECT: technical result is the creation of a detergent with high detergent capacity with respect to a wide range of contaminants in a situation where the scale contains oil products with low corrosion activity and low consumption rates of the detergent.

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Description

Technology area

The descaling agent is a detergent. The invention relates to acidic detergents based on organic acids and can be used at enterprises where scale is formed during operation of the equipment. These include both enterprises of the chemical and petrochemical industry, and the fuel industry.

State of the art

Known composition for descaling (patent RU No. 2085517, publ. 27.07.1997), containing wt.% Bisulfate or pyrosulfate of potassium or sodium 5-12, water - the rest. The composition can also contain hydrochloric and acetic acids in the amount of 4-8 and 4-6 wt.%, Respectively. Acetic acid is quite active in destroying scale, but it is volatile and has a pungent unpleasant odor.

There is a known method of chemical cleaning during operation of heat exchange equipment from scale, as well as the formation on the surfaces of heat exchange of a film that protects against re-scale formation (patent RU No. 2285218, publ. 10.10.2006). This method includes the treatment of internal heating surfaces with solutions with repeated circulation and subsequent removal of scale; as a solution, an aqueous solution of a specially repair-reduction composition is used, consisting of rocks crushed to a fineness of 0.07-0.075 mm, including oxides of the elements: SiO ₂ , TiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , FeO, MnO, MgO, CaO, Na ₂ O, K ₂ O, P ₂ O ₅ , SO ₃ , CO ₂ , H ₂ O, used in an amount of at least one gram per one liter of the volume of the processed equipment, while the circulation of the solution is carried out at the temperature of the operating mode of the equipment, and the descaling is carried out by blowing water or steam after at least 72 hours of circulation of the solution. Studies have shown that this method is energy-intensive and requires an increase in the equipment downtime for repair.

A known composition for removing deposits and scale from the inner surfaces of heat exchange equipment (patent RU No. 2331591, publ. 20.08.2008). The composition consists of sodium or potassium pyrosulfate, or ammonium or sodium or potassium persulfate, or ammonium, polyphenolic compounds of wood or coniferous bark, urotropin, a nonionic surfactant, hydrochloric acid, acetone and water with the following content of components, wt%: sodium pyrosulfate or potassium, or ammonium or sodium or potassium persulfate, or ammonium 0.09-10; polyphenolic compounds of wood or coniferous bark 0.003-6.0; urotropin 0.01-4; nonionic surfactant 0.0015-0.1; hydrochloric acid 2.0-24.0; acetone 1.0-8.0; water is the rest.

So, a known composition for descaling (patent RU No. 2257354, publ. 27.07.2005), containing sodium or potassium pyrosulfate, or ammonium or sodium or potassium persulphide, or ammonium, hydrochloric acid, nonionic surfactant, polyphenolic compounds of coniferous bark, inhibitor corrosion - urotropine, polyhexamethylene guanidine chloride and water.

Also known is a composition for removing scale and deposits (patent RU No. 2324661, publ. 20.05.2008), which contains sodium pyrosulfate, or potassium, or ammonium or sodium persulfate, or potassium, or ammonium, sodium fluoride, or ammonium, or potassium, or hydrofluoric acid, polyphenolic compounds of wood or softwood bark, urotropin, hydrochloric acid, a nonionic surfactant, and water.

Also known is a composition for removing scale from heat exchange surfaces (patent RU No. 2443637, publ. 27.02.2012), containing hydrochloric acid in an amount of 2-15 wt.%, Corrosion inhibitor - urotropin or thiourea - 0.5-3%, sodium fluoride , potassium or ammonium - 1-4%, meta-nitrobenzenesulfonic acid - 3-7% and water - the rest up to 100%.

The method for removing scale from heat exchange equipment (patent RU No. 2449234, publ. 04/27/2012) is based on the same principles, which includes, after examining the internal surfaces of the cooling system, processing the internal surfaces of the cooling system with chemical reagents in the following sequence: filling it with a solution, containing 4.0% hydrochloric acid, 1.5% urotropin, 0.5% magnesium silicate, kept under the solution for 1.0 hour and repeated circulation of the solution, flushing the cooling system with water and neutralizing the residual solution, after which the cooling system is filled with a solution (pH 2.0-3.0) containing 8.8% orthophosphoric acid is kept under the solution for 1.0 hour and the solution is repeatedly circulated, the cooling system is flushed and the residual solution is neutralized, and the final inspection of the purification quality is carried out.

The disadvantages of the described technical solutions are common. Strong mineral acids, especially hydrochloric acid, not only actively dissolve the metal surface, but also destroy the protective passive layers on the surface of metals such as stainless steel. This leads to corrosion of metal equipment, especially in the areas of welds and joints of dissimilar metals. Urotropine in a strong acid medium partially decomposes with the formation of formaldehyde, which has an unpleasant odor and carcinogenic effect. The use of the described means in a domestic environment is associated with the danger of chemical burns, poisoning, and cancer. In addition, when using the described means, the complex problem of disposal of the remains of the used means arises.

The second group of compositions for descaling include compositions containing chelating agents. Complexones actively bind atoms of calcium, magnesium, iron and other metals contained in the sediments, which leads to the destruction of these latter.

Such a composition has a flushing composition for descaling (patent RU No. 2172301, publ. 20.08.2001), which contains a complexone (Trilon-B), sodium phosphate monosubstituted, isopropyl alcohol, quaternary ammonium salt of perfluorosulfonic acid, water. The composition may additionally contain fluorescein.

Compositions containing complexones are also proposed for use in everyday life. So, known antiscale for removing scale from the inner metal walls of household appliances, including washing machines, dishwashers, steam generators (patent RU No. 2213069, publ. 09/27/2003), which contains, wt%: sulfamic acid - 85 -90; ammonium chloride - 8-10; thiourea - 0.5-1; complexone - nitrilotrimethylphosphonic acid - 1-4.5.

It is also known a detergent for descaling heating elements and internal surfaces of washing machines (patent RU No. 2334790, publ. 09/27/2008), which contains, wt%: sodium tripolyphosphate - 39, sodium carbonate - 42, sodium chloride - 12, zeolite or bentonite - 4, ethoxylated with 8-10 moles of ethylene oxide nonylphenol - 2, chelator - sodium salt of ethylenediamine tetraacetic acid - 1.

A common disadvantage of all agents containing chelating agents is that chelators, interacting intensively with metal ions, actively destroy the metal parts of the equipment. Metallic acid corrosion inhibitors that can protect metals from positively charged hydrogen ions do not prevent exposure to negatively charged complexone ions. Complexones also extract metal oxides from glass, ceramics, enamel coatings and other parts, which leads to their clouding and spoils the appearance of household appliances.

The mildest detergents, which are also environmentally friendly, are compositions based on natural or similar natural organic acids (acetic, citric, etc.), or organic sulfonic acids.

Thus, there is a known method of surface cleaning from contamination (patent RU No. 2209854, publ. 08/10/2003), which includes treatment with heating with a washing aqueous solution including acetic acid, aluminum or iron hydroxides, or a mixture thereof. Aluminum hydroxide is introduced in an amount of 100-660 ml with a pH of 6.5, glacial acetic acid from 10 to 45 ml and water up to 1 liter. The pH of the washing aqueous solution with the introduction of aluminum hydroxide is more than 3, with the introduction of iron hydroxide or a mixture of aluminum and iron hydroxides more than 6. The minimum heating temperature is 75 ° C. Boiling is carried out with the removal of solid foam that appears when the scale dissolves.

However, the compositions of the third group have a low washing capacity and the rate of dissolution of scale deposits (especially if these latter have a multicomponent composition). Also, the need to remove solid foam from washed deposits makes the surface cleaning process laborious, and if the foam is not removed, then the washed particles can be adsorbed and cemented on the surface to be cleaned again. In addition, many organic acids (acetic, formic, propionic, etc.) have a pungent specific odor that makes them difficult to use in domestic conditions.

The closest to the invention in terms of the technical essence and the achieved effect is the composition of the means for cleaning equipment in the food and processing industry (patent RU No. 2429287, publ. 09/20/2011) for removing complex mineral-organic deposits from metal surfaces, as well as ceramics and glass. The product contains orthophosphoric acid, hydrochloric acid, a nonionic surfactant (alkyldimethylamine oxide), a cationic surfactant surfactant (Catamine AB - alkyldimethylbenzinammonium chloride) and water. To increase the detergency against a wide range of dirt, while having inhibitory properties, the agent additionally contains citric acid, sodium hydroxyethylene diphosphonic acid and urea (carbamide). The disadvantage of this agent is the lack of detergency in relation to mineral contamination. This product bears the closest resemblance to our descaler. The use of lactic acid in addition to citric acid and urea also increases the efficiency of the finished solution.

Disclosure of invention

The technical result of the invention is the elimination of these drawbacks and the creation of a cleaning agent with a high detergency in relation to a wide range of contaminants in a situation where the scale contains oil products, reduced corrosivity and low consumption rates of the cleaning agent.

The specified technical result is achieved by the fact that the preparation for descaling and cleaning the inner surfaces of heat and power and technological equipment from scale deposits contains: urotropine, thiourea, urea, which prevent corrosion of the equipment during its cleaning and have a protective effect of scale formation, lactic and citric acids, nonionic surfactants: Triton X-100 and TWEEN-80, which increase the drug's ability to dissolve scale, a dye-indicator of pH level (methyl red), which changes color to yellow-brown when shifted to the neutral zone, with the following ratio of components, wt%: urea - 3.5-3.7; lactic acid - 7-7.5; citric acid - 7-7.5; urotropine - 0.3-0.5; thiourea - 0.3-0.5; Triton X-100 - 1-2; TWEEN-80 - 0.5-1; methyl red - 0.1-0.2; water - 77.1-80.3.

The invention relates to a mineral detergent. The drug was developed for cleaning heat and power and technological equipment at the enterprises of the oil refining complex. Such equipment, in addition to scale, is also contaminated with various oil products. Often oil products and scale deposits are baked together and are not subject to decomposition with standard detergents. In addition, the preparation also contains additives that prevent corrosion of equipment during cleaning and have a protective effect of scale formation. Cleaning can be done without disassembling equipment: during cleaning, the solution circulates in a closed circuit and does not damage the seal and rubber materials. Additionally, it also contains a dye-indicator of the pH level, which changes color when shifted to the neutral zone. When the color of the preparation changes from red to orange-yellow, we can conclude that the preparation's capabilities for cleaning equipment have been exhausted and the spent preparation can be disposed of without special measures by draining it into the sewer.

The drug can be obtained by mixing the components.

The basis for the preparation of the descaling agent is acids in dry and liquid form. Together with surfactants (surfactants), their ability to dissolve scale increases significantly.

To prepare the product for descaling at all stages, it is necessary to completely dissolve the components. If crystals or viscous lumps of surfactant remain, over time they will not dissolve on their own and are a marriage.

The preparation of the drug must be carried out in strict sequence. Failure to follow this sequence can lead to the rejection of the entire batch!

Implementation of the invention

A preparation for descaling and cleaning the inner surfaces of heat power and technological equipment from scale deposits is prepared as follows.

Based on the volume of the batch being produced, half the volume of distilled water is introduced into the reactor. With the mixer turned on (30-60 rpm), carbamide, urotropine and thiourea are added. Stir for 5 minutes. Visually assess the absence of mechanical inclusions of undissolved solids. Bring the volume of distilled water to 85% of the batch size. Heated to a temperature of 25-30 ° C. Surfactants are prepared separately: Triton X-100 and Tween 80 are introduced into a total container with a volume of 15-20 liters. Distilled water is added (10% of the total volume of the batch produced). Stir until smooth. Poured into a reactor. Stir the surfactants in the reactor until a homogeneous state (no lumps should remain in the mixture, if it does not dissolve - increase the heating to 40 ° C and stir until complete dissolution. Add citric acid to the reactor. Stir until dissolved for 5-10 minutes. Add lactic acid to the reactor Stir until dissolved for 3-5 minutes.

Introduction of the indicator. The required volume of methyl red indicator is added to the container. Distilled water is added. Stir until complete dissolution. The indicator solution is introduced into the reactor. Stir until smooth.

Scale removal tests were carried out at JSC GAZPROMNEFT-MNPZ. In tests carried out on 13 November 2019, a heat exchanger with two circuits was used. To clean its inner contour, a heated solution for descaling was pumped into it.

During the cleaning procedure, the process was accompanied by an abundant release of foam. It occupied a significant volume and, as a result, the solution increased its volume and began to overflow over the edge of the container. Hence, we can conclude that in the future it is necessary to reduce the volume of the poured solution by 10-20% of the total volume of filling the container.

After the cleaning procedure, a layer of pieces of rust about 15-20 cm thick formed at the bottom of the cube. It should be noted that the rust from bright red (siderite - iron carbonate) turned red (hematite - iron oxide). Thus, a chemical reaction took place not only with carbonate deposits, but also with iron. Iron oxide is a more chemically inert substance.

Thus, the use of the claimed preparation provides improved washing and cleaning characteristics against a wide range of contaminants, including when scale contains oil products. Also, the drug has a reduced corrosivity and low consumption rates.

Comparative analysis of the claimed preparation shows that the totality of its essential features is unknown from the prior art and, therefore, meets the “Novelty” patentability condition.

In the prior art, no features have been identified that coincide with the distinctive features of the claimed preparation and affect the achievement of the claimed technical result, therefore, the claimed invention meets the patentability condition "Inventive step".

The above information confirms the possibility of using the claimed preparation for descaling and cleaning the internal surfaces of equipment from scale deposits, and therefore meets the requirement of patentability "Industrial applicability".

Claims (2)

A preparation for descaling and cleaning the internal surfaces of heat and power and technological equipment from scale deposits, containing: urotropin, thiourea, urea, lactic and citric acids, nonionic surfactants: Triton X-100 and TWEEN-80, methyl red dye-indicator of pH level and water , with the following ratio of components, wt%: urea 3.5-3.7 lactic acid 7-7.5 lemon acid 7-7.5 urotropin 0.3-0.5 thiourea 0.3-0.5 triton X-100 1-2 TWEEN-80 0.5-1 methyl red 0.1-0.2 water 77.1-80.3