RU2324661C2 - Composition for removal of scale and deposit - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: composition contains sodium or potassium or ammonium pyrosulphate or sodium or potassium or ammonium persulphate, 0.09-10% w/w, sodium or potassium or ammonium fluoride or hydrofluoric acid - 0.01-1.0 %w/w, polyphenolic compounds of wood or conifer rind - 0.003-6.0 %w/w, urotropine - 0.01-8.0 %w/w, hydrochloric acid - 2.0-24.0 % w/w, non-ionic detergent -0.0015-0.0% w/w, and water - the rest.

EFFECT: proposed composition improves dissolution of slightly soluble scale and deposits containing silicates.

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Description

The invention relates to the petrochemical, chemical industry, power system, water supply and other sectors of the economy, namely, compositions for removing scale and deposits from the inner surfaces of pipes, heat exchangers and process apparatuses.

A known composition for descaling includes in wt.% (Patent RU No. 2085517) containing wt.% Potassium or sodium bisulfate or persulfate 5-12, water - the rest. The composition may also contain hydrochloric and acetic acids in an amount of 4-8 and 4-6 wt.%, Respectively.

The closest to the invention in technical essence and the achieved effect is the composition (Patent RU No. 2257354), including in wt.% Sodium pyrosulfate, or potassium, or ammonium, or sodium sulphate, or potassium, or ammonium - 0.09-10 wt. %, hydrochloric acid - 2.0-15.0, polyphenolic compounds of coniferous bark 0.003-2.0, urotropin 0.01-4.0, polyhexamethylene guanidine chloride - 0.1-1.5, nonionic surfactant - 0.0015-0.009, water - the rest.

The disadvantage of these compositions is their low dissolution rate of scale and deposits containing sparingly soluble silicates.

To eliminate this drawback, a composition in wt.% Is proposed that increases the rate of dissolution of scale and deposits containing silicates:

sodium pyrosulfate, or potassium, or ammonium, or sodium sulfate, or potassium, or ammonium 09.09-10 sodium fluoride, or ammonium, or potassium, or hydrofluoric acid 0.01-1.0 polyphenolic wood compounds or coniferous bark 0.003-6.0 urotropin 0.01-8.0 hydrochloric acid 2.0-24.0 nonionic surfactant substance 0.0015-0.05 water rest

Example 1. The composition of example 1 is prepared under the conditions of the prototype and contains (wt.%): Sodium pyrosulfate - 2; hydrochloric acid - 2.0; urotropin - 2; polyphenolic compounds of coniferous bark - 1; polyhexamethylene guanidine chloride - 1; surfactant - 0.0015; water is the rest.

The rate of dissolution of the scale was measured by the rate of weight loss of a bar consisting of CaCO ₃ : Ca ₃ PO ₄ : CaSiO ₃ = 30: 50: 20 under conditions of mixing and temperature control of the composition at 45 ° C and a contact time of 1 hour.

Testing for corrosion activity of solutions of scale converters was carried out as follows. Fat-free metal samples with the same surface were weighed on an analytical balance with an accuracy of 0.0001 g. After weighing, the samples were soaked in the test composition. At the end of the experiment, metal samples were removed from solutions, washed in running water, dried and weighed. Analysis of the results was carried out based on the difference in mass of the samples before and after processing them in the studied solutions.

Under similar conditions, the compositions shown in the remaining examples were analyzed.

Example 2. The tests are carried out under the conditions of example 1. The composition of example 2 is prepared in the conditions of the prototype. In contrast to example 1, the composition contains in wt.%: HCl - 15.0; sodium pyrosulfate - 2; urotropin - 4; polyphenolic compounds of coniferous bark - 2.0; polyhexamethylene guanidine chloride - 1.5; Surfactant - 0.0015; water is the rest.

Example 3. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 2.0; urotropin - 2.0; ammonium sulphate - 2.0; polyphenolic compounds of coniferous bark - 1; sodium fluoride - 0.05; Surfactant - 0.0015; water is the rest.

Example 4. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 2.0; ammonium pyrosulfate - 2.0; urotropin - 2.0; polyphenolic compounds of coniferous wood - 1.0; ammonium fluoride - 0.5; Surfactant - 0.03; water is the rest.

Example 5. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 15.0; ammonium sulphate - 2.0; urotropin - 4.0; polyphenolic compounds of coniferous wood - 2.0; ammonium fluoride - 1.0; Surfactant - 0.05; water is the rest.

Example 6. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 24.0; potassium sulfate - 10.0; urotropin - 8.0; polyphenolic compounds of coniferous wood - 6.0; ammonium fluoride - 1.0; Surfactant - 0.05; water is the rest.

Example 7. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 15.0; ammonium pyrosulfate - 2.0; urotropin - 4.0; polyphenolic compounds of coniferous wood - 2.0; hydrofluoric acid - 1.5; Surfactant - 0.07; water is the rest.

Example 8. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 15.0; sodium sulfate - 0.09; urotropin - 0.01; polyphenolic compounds of coniferous bark - 0.003; ammonium fluoride - 1.0; Surfactant - 0.03; water is the rest.

Example 9. The tests are carried out under the conditions of example 1. In contrast to example 1, the composition contains in wt.%: HCl - 15.0; potassium pyrosulfate - 11; urotropin - 9.0; polyphenolic compounds of coniferous wood - 6.5; sodium fluoride - 0.3; Surfactant - 0.07; water is the rest.

The results of the relative dissolution rates of deposits and the degree of corrosion protection relative to the prototype (example 2) are presented in the table.

Example No. The rate of dissolution of scale,% The degree of protection against corrosion,% one 42 133 2 one hundred one hundred 3 60 133 four 67 130 5 141 106 6 247 78 7 159 93 8 140 74 9 96 160

As can be seen from a comparison of the data of examples 1 and 3 and examples 2 and 5 (table), the introduction of fluorine-containing compounds in the composition increases the dissolution rate of deposits containing silicates. In this case, the corrosion rate of the metal does not increase. A further increase in the content of fluorine-containing compounds (example 7) shows that the dissolution rate of deposits increases slightly, however, the metal corrosion also increases.

When comparing the activity and the effect on the metal corrosion of examples 3 and 4, it can be seen that, as corrosion inhibitors, it is possible to use not only polyphenolic compounds of coniferous bark, but also polyphenolic compounds of coniferous wood, which allows expanding the raw material base for obtaining scale and sediment removal compositions.

When comparing examples 1 and 3, examples 3 and 4, it is seen that the replacement of pyrosulphate and (or) sulphate salt with ammonium sulphate does not affect the amount of corrosion.

When comparing the data of examples 4, 5 and 6, it is seen that an increase in the content of hydrochloric acid increases the dissolution rate of deposits, but also increases the corrosion of the metal. An increase in the content of hydrochloric acid above 24% is not economically feasible, since it is not completely consumed in the process of dissolving scale and requires additional costs aimed at neutralizing it in the spent solution, as well as due to the high corrosion of the metal. The decrease in the content of hydrochloric acid below 2.0 wt.% (Examples 3 and 4) reduces the dissolution rate of scale, which requires an increase in surface treatment time.

A decrease in the content of acid corrosion inhibitors (examples 5 and 8): polyphenolic compounds of bark and (or) softwood, urotropine and sodium pyrosulfate, or potassium, or ammonium, or sodium sulfate, or potassium, or ammonium, leads to a sharp increase in metal corrosion. The increase in their content (example 9) leads to a slowdown in the rate of dissolution of sediments.

A comparison of the data of examples 3 and 4 shows that increasing the concentration of surfactants increases the rate of dissolution of scale, however, a further increase in surfactants (example 7) leads to high foaming, which makes it difficult to work with the composition.

The most optimal is given in examples 3, 4, 5, 6, 8 of the concentration of the ingredients of the composition: sodium pyrosulfate, or potassium, or ammonium, or sodium sulphate, or potassium, or ammonium 0.09-10; sodium fluoride, or ammonium, or potassium, or hydrofluoric acid (HF) - 0.01-1.0; polyphenolic compounds of wood or coniferous bark 0.003-6.0; urotropin 0.01-8.0; HCl (hydrochloric acid) - 2.0-24.0; nonionic surfactant (surfactant) 0.0015-0.05; water is the rest.

Claims (1)

Composition for descaling and deposits, containing a water-soluble salt of sulfur-containing acid, urotropin, nonionic surfactant and hydrochloric acid, characterized in that it further contains hydrofluoric acid or sodium, potassium or ammonium fluoride, as a salt of sulfur-containing acid contains sodium, potassium pyrosulfate or ammonium or sodium sulfate, potassium or ammonium, as well as polyphenolic compounds of wood or coniferous bark in the following ratio of components, wt.%: sodium pyrosulfate, or potassium, or ammonium, or sodium sulfate, or potassium or ammonium 09.09-10 sodium fluoride, or ammonium, or potassium, or hydrofluoric acid 0.01-1.0 polyphenolic wood compounds or coniferous bark 0.003-6.0 urotropin 0.01-8.0 hydrochloric acid 2.0-24.0 nonionic surfactant substance 0.0015-0.05 water rest