RU2177458C1 - Composition for removing high-temperature mineral salt deposits from thermal power equipment - Google Patents

Abstract

FIELD: thermal power industry, particularly, chemical cleaning from high-temperature mineral deposits of steam and hot-water boilers. SUBSTANCE: composition comprises nitrile (methylenephosphonic) acid, methyliminodimethylene phosphonic acid, hydrochloric acid and acid corrosion inhibitor, ratios of components being as follows, wt.%: nitriletri-(methylenephosphonic) acid, 14-16; methylimino dimethylene phosphonic acid, 4-7; hydrochloric acid, 1-14; acid corrosion inhibitor, 0.5-1.0; and water, the balance. EFFECT: removal of high-temperature mineral deposits, improved cleaning efficiency, reduced volume of sewage after washing operation.

Description

 The invention relates to the field of power engineering and can be used for chemical cleaning of high-temperature mineral deposits of steam and hot water boilers.

 A known composition for removing iron oxide deposits including nitrile triacetic acid (NTA) - 40-70 g / l, carboxylated derivative of polyoxypropylene (KPPPA) (2-hydroxy-1,3-diaminopropane NNN'N'-tetraacetic acid) - 10-40 g / l, sulfuric or phosphoric acid - 4-10 g / l, water - the rest [USSR Author's Certificate N 1534287 IPC F 28 G 9/00, 1990].

 However, this composition is not effective for removing high-temperature mineral deposits. In addition, the wastewater generated during the washing process cannot be disposed of and discharged into the general sewage system.

 Closest to the proposed, is a composition for removing deposits on the basis of the mother liquor of the production of nitrile trimethylene phosphonic acid (NTP) -diphalon. [N.M. Dyatlova, V.Ya. Temkina, K.I. Popov. Complexons and complexonates of metals, M.: Chemistry, 1988, 544 p.]. Diphalon is produced in accordance with TU 6-02-12-134-87 with the following composition: nitrile trimethylene phosphonic acid (NTP) content ≥15%, hydroxyethylidene diphosphonic acid (OEDP) 5-7%, hydrochloric acid 10-15%, corrosion inhibitor 0, 5-1%. To remove deposits use a diluted solution of diphalon with an acidity of 0.25-0.5 mol / L. The solution can be used to a concentration of 0.1-0.15 mol / L in acidity. The known composition, due to lack of effectiveness can only be used to remove carbonate deposits.

 The objective of the invention is the creation of a composition that allows you to remove high-temperature mineral deposits, increase the efficiency of treatment while reducing the volume of wastewater after washing.

This object is achieved by the fact that to remove scaling, a composition is used that contains nitrile tri (methylenephosphonic) acid (NTF) and methyliminodimethylenephosphonic acid (MIDP), hydrochloric acid, an acid corrosion inhibitor and water as the active base in the following ratio of components, wt.%:
Nitrile tri (methylenephosphonic) acid (NTP) - 14-16
Methyliminodimethylenephosphonic Acid (MIDP) - 4-7
Hydrochloric acid - 10-14
Acid Corrosion Inhibitor - 0.5-1.0
Water - Else
The introduction into the inventive composition of a mixture of NTF and MIDF in the claimed amounts provides a new technical result - the expansion of the scope, namely the effective effect on high-temperature mineral deposits, a significant increase in the "capacity" of Fe ³⁺ , Cu ^{2+ ions} , while reducing wastewater volumes .

 The inventive composition differs from the compositions known for these purposes by the new active ingredient methyliminodimethylenephosphonic acid (MIDP), which is introduced into the composition in the claimed ratio.

 All of the above allows us to conclude that the claimed composition meets the criterion of "inventive step".

Метилиминодиметиленфосфоновую кислоту получают по реакции Лейкарта-Валлаха взаимодействием иминодиметиленфосфоновой кислоты с формальдегидом в среде муравьиной кислоты:

МИДФ представляет собой известное вещество, описанное в научно-технической литературе (см. , например, В.Я.Темкина, Н.В.Цирульникова, Р.П.Ластовский. Синтез комплексонов. Ж. ВХО им. Д.И.Менделеева, 1989, т. 29, вып. 3, с. 53- 60). В качестве соляной кислоты может быть использована любая соляная кислота, в т.ч. ингибированная соляная кислота, включающая ингибитор коррозии черных металлов ПБ-5, выпускаемая по ТУ 6-01-730-72. В качестве ингибитора коррозии цветных металлов может быть использован любой ингибитор кислотной коррозии, например бензотриазол, выпускаемый по ТУ 6-09-1291-87.For the manufacture of the claimed composition using: nitritimethylene phosphonic acid (NTF), manufactured according to TU 6-02-1171-79; methyl iminodimethylene phosphonic acid (MIDP) of the formula

Methyliminodimethylenephosphonic acid is obtained by the Leucart-Wallach reaction by the interaction of iminodimethylenephosphonic acid with formaldehyde in formic acid medium:

MIDP is a well-known substance described in the scientific and technical literature (see, for example, V.Ya. Temkina, N.V. Tsirulnikova, R.P. Lastovsky. Synthesis of complexones. J. VCO named after D.I. Mendeleev, 1989, vol. 29, issue 3, pp. 53-60). As hydrochloric acid can be used any hydrochloric acid, including inhibited hydrochloric acid, including the ferrous metal corrosion inhibitor PB-5, manufactured according to TU 6-01-730-72. As an inhibitor of non-ferrous metal corrosion, any acid corrosion inhibitor, for example benzotriazole, manufactured according to TU 6-09-1291-87 can be used.

 The inventive composition received the trade name "Ruston" and is illustrated by the following examples of specific performance.

Example 1
Deposits from a power boiler TGM-151B N 1 CHP JSC AO Uralmetprom composition,%: SiO ₂ 1.3; Fe ₂ O ₃ 35.4; CuO 29.8; CaO + MgO 7.34; P ₂ O ₅ 7.74, previously ground in a mortar to a homogeneous mass. A portion of the deposits of 1 g is placed in a glass and pour 100 ml of a solution of the composition "Ruston" pre-diluted with water in a ratio of 1: 5. Dissolution is performed at 60 ^o C under agitation (Re _p = 6,000). The amount of dissolved deposits is determined gravimetrically. Exposure time 1-4 hours. At the end of the exposure, the volume of water required to wash off the undissolved part of the precipitate until the absence of C1 ions in the filtrate was estimated.

 At the same time, tests are carried out in accordance with known formulations.

 The ratios of the components in the composition of "Ruston" for chemical cleaning and their properties are presented in table. 1.

 From the data presented in table. 1, it is seen that the efficiency of dissolution of deposits using the claimed composition is higher than that of the known, and the volume of water for washing insoluble sediment is much less.

 In our opinion, the higher compositional efficiency is probably due to the greater selectivity of MIDP in the formation of complexes with Fe and Cu ions (the main components of deposits).

 The increase in the capacity of the proposed composition for iron ions and copper ions is illustrated by the following examples.

Example 2
Samples of the sediments of the composition shown in Table 2 are placed in a thermostated glass, filled with 100 ml of the "Difalon" and "Ruston" compositions at the optimum ratio of components. The dissolution is carried out with stirring and 60 ^o C until equilibrium is reached, i.e. until the moment after which the concentration of iron and copper in the solution ceases to change. Calculate the amount of iron and copper passing into the solution (mg per 1 g of composition).

 The data are presented in table. 2.

 From the data presented in table. 2 shows that the proposed compositions have a capacity for iron and copper more than a similar characteristic of the prototype by 30-50%. Obviously, this circumstance explains its higher efficiency.

 The composition "Ruston" worked out after dissolution of deposits can be used to prevent deposits and corrosion. This allows for almost complete utilization of the solution.

Example 3
The spent mother liquor (acidity 0.1-0.12 M) was filtered off from the solid phase and the content of organophosphonates was determined by a standard method. The total content of organophosphonate was about 3%. Testing the effectiveness of the spent solution was carried out in accordance with TU 6-05-2021-86 for the IOMS reagent, and the inhibition of crystallization of calcium sulfate and calcium carbonate was determined.

 To assess the corrosion resistance, samples of steel 20 and brass L-68 were taken and placed for 24 hours in spent solutions. The value of corrosion was determined by the gravimetric method.

 The data are presented in table. 3.

 From the data presented in table. 3, it can be seen that the spent Ruston mother liquor at optimal component ratios can be used to prevent deposits of both sulfate and calcium carbonate. Moreover, in terms of the effectiveness of the above deposits, it is not inferior to the IOMS inhibitor used in water treatment for the same purpose. Thus, when using the inventive composition, not only the scope of use is expanded, but also the problem of waste disposal during washing is solved (mother liquors after washing, as a rule, are drained into the sewer), reagent treatment is cheapened by using waste from washing.

Claims (1)

Composition for removing high-temperature mineral deposits from thermal power equipment containing nitrile tri (methylenephosphonic) acid, hydrochloric acid, an acid corrosion inhibitor and water, characterized in that it additionally contains methyliminodimethylenephosphonic acid in the following ratio of components, wt.%:
Nitrile tri (methylenephosphonic) acid - 14-16
Methyliminodimethylenephosphonic acid - 4-7
Hydrochloric acid - 10-14
Acid Corrosion Inhibitor - 0.5-1
Water - Else

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