SU1366858A1 - Method of cleaning heat exchange surfaces of scale - Google Patents

Abstract

The invention relates to the field of energy and allows to expand the technological capabilities of the method by reducing the corrosion rate of brass surfaces while ensuring effective descaling. Prepare a solution by mixing the following components, wt%: hydrochloric acid 3.0-10.0; corrosion inhibitor 0.05-2.00; defoamer 0.00001-0.001; organic aminophosphonate 0.3-1, 0; inorganic; ifca zinc salt 0.1-0.5; the rest is water. This solution was used to wash the surface of brass heat exchangers at the rate of movement of the solution O, 2-1.2 m / s. Nitrilotrimethylenephosphonic acid, mineral salt deposition inhibitor (IOMS-1), 2-OXI-1,3-propylenediamine-K, K, M, N-tetrlmethylenephosphonic acid are used as the organic aminophosphonate, and the inorganic zinc salt is sulfate zinc, zinc chloride or zinc wastes from the production of theophylline, as a corrosion inhibitor of carbon steel - captax, catapine, hexamine, I-1-B or PB-5, as a defoaming agent - synthetic fatty acids of the С 5-Cg, fq fraction, Cg- CD 6 tab. i (L co 05 O5 oo P1 00

Description

The invention relates to a method of cleaning brass heat exchanging surfaces from scale and can be used in the power industry in washing heat exchangers, boilers, water heaters and other equipment made of brass.

The aim of the invention is to reduce the corrosion rate of the brass surface while at the same time ensuring effective descaling.

Example. An aqueous solution containing, in%: 5 hydrochloric acid 5, an inhibitor I-1-B 0.5; synthetic fatty acids (FFA) fraction With 0,001; nitrilotri-; methylenephosphonic acid (NTF) 0.6 and zinc sulphate 0.3. For-prida-; Neither a solution of increased aggressiveness, usually acquired during washing, is injected with sulphate. copper — 2.0 g / l of Cu and iron chloride — to a content of 2.0 g / l of Fe. The solution is placed in a laboratory circuit-circulating model, including a flush pump, two samples and an intermediate tank, made of steel and steel 3. Samples are made of brass (L-68) tube. The first sample had on its inner surface a layer of carbonate sediments 1.0–1.5 mm thick and was intended to determine the degree of washing of sediments. The second sample had a clean inner surface and was designed to determine the effectiveness of corrosion inhibition. The rate of movement of the solution in the samples was maintained at 0.5 m / s, the duration of the laboratory tests was 4 hours, the temperature of the solution was about 20 ° C.

The degree of washing of carbonate deposits was determined by the gravimetric method according to the formula

 %

PI

where P is the amount of sediment on

the inner surface of the sample before washing, g; RP - the amount of sediment on

the inner surface of the sample after washing, g. The corrosion rate of brass is determined on a sample that had no deposits, by the gravimetric method according to the formula

WITH

F-T

g / m

where M is the weight of the sample before washing, g;

sample weight at the end of washing, g;

the area of the inner surface of the sample, m2; washing time, h. The corrosion inhibitory effect of brass was calculated from

E -2jii.I-Sli. 100%

 T KI

where С „

corrosion rate of brass during washing of sediments by a known method, g / shch; The corrosion rate of brass during the washing of sediments by the proposed method, g / mAh. Table 1 shows the results of the effectiveness of inhibiting corrosion of brass depending on the composition and ratio of the components of the composition at a solution circulation rate of 0.5 m / s.

At the same time, the experiment was carried out to determine the effectiveness of inhibiting the corrosion of brass during the removal of scale from the heat exchangers with a known solution of hydrochloric acid containing a corrosion inhibitor of carbon steel and synthetic fatty acids.

In tab. Table 1 also provides information about the effectiveness of brass corrosion inhibition during heat washing. from the scale of the proposed method at the circulation rate of a solution of 0.5 m / s, the variation of the composition and ratios of hydrochloric acid, the inhibitor I-1-B, the defoaming agent — synthetic fatty acids, the organic aminophosphonate — lotrymethylenephosphonic acid and zinc sulfate.

The results of brass corrosion inhibition efficiency were considered only if 100% degree of washing of carbonate deposits was provided.

Table 2 summarizes the effectiveness of inhibiting corrosion of brass when washing heat exchangers from scale at a circulation rate of 0.5 m / s, depending on the type of organic aminophosphonate with a content,%: HC1 5; I-1-B 0.5; FFA 0.001; zinc sulfate 0.3. In this case, nitrilotrimethylenephosphonic acid (NTF) is used as an inhibitor of mineral salt deposits.

(IOMS) and 2-hydroxy-1,3 propylenediamic-NjNjN, N-tetramethylenophosphonic acid (DFT).

Table 3 summarizes the effectiveness of inhibiting the corrosion of brass when washing heat exchangers from scale at a circulation rate of 0.5 m / s, depending on the type of inorganic zinc salt at a content,%: HC1 5; I-1-B 0.5; FFA 0.001; NTF 0.6.

Table 4 summarizes the effectiveness of inhibiting the corrosion of brass when washing heat exchangers from scale at a circulation rate of 0.5 m / s depending on the type of carbon steel corrosion inhibitor at a content of,%: HC1 5; FLC 0,001j NTF 0.6} zinc sulfate 0.3

Table 5 presents information about the effectiveness of inhibiting the corrosion of brass when washing heat exchangers from scale at a circulation rate of 0.5 m / s, depending on the type of defoaming agent — synthetic fatty acids (FFA) at a content,%: HC1 0.5; I-1-B 0.5; NTF 0.6; zinc sulfate 0.3; FFA 0.001.

Table 6 provides information about the effectiveness of inhibiting the corrosion of brass when washing heat exchangers from scale depending on the rate of circulation of the solution at a content of,% HC1 5; I-1-B 0.5; FFA 0.001; NTF | a, 6; ZnSO 0.3.

; From the data in the table it is clear that the proposed method of cleaning the surface of brass heat exchangers from kakipi reduces the corrosion rate of brass by 91.1- 93.3% while maintaining the 100% descaling efficiency.

The present invention is of great practical importance when cleaning from scale brass heat exchangers, boilers, water heaters and other equipment that have been in operation for a long time; provides a significant reduction in corrosive wear of brass equipment during chemical cleaning;

13668584

Claims (1)

allows you to do chemical descaling using relatively cheap reagents for a systematic operation, thereby saving fuel and energy resources and the cost of repair work. Invention Formula 15 20 ten The method of cleaning heat-exchange surfaces from scale by rinsing them with an aqueous solution containing hydrochloric acid, a corrosion inhibitor, selected from the group including captax, catapine, urotropine, product based on higher pyridine bases (I-1-B), the product of aniline condensation with urotropine (PB-5) and defoamer, characterized in that, in order to expand the technological capabilities of the method by reducing the corrosion rate of brass surfaces with 25 at the same time ensuring effective descaling, an organic aminophosphonate selected from the group containing nitrilotrimethylenephosphonic acid, an inhibitor of mineral salt deposits (IOMS-1) and 2-hydroxy-1,3-propylenediamine-K, H M, N-tetramethylene phosphonic acid and inorganic zinc salt selected from the group 40 Zones containing zinc sulphate, zinc chloride and zinc wastes of theophylline production, synthetic fatty acids of fractions C,, j, C - C are used as defoaming agent with the following ratio of components, wt.%: five 0 Salt Acid Corrosion Inhibitor Defoamer Organic Aminophosphonate Inorganic Zinc Salt Water 3.0-10.0 0.05-2.0 0.001-0.00001 0.3-1.0 0.1-0.5 Else and washing is carried out at a speed of movement of the solution of 0.2-1.2 m / s. Table I .Table 3 Zinc waste production of theophylline 0.3 (according to Znf-iO) C - C - 100  D6 C. - C 100 С „- С 100 1 ten 100 Oh 12 93.2  Table 5 0.12 88, D 0.12 88.4 0.12 88.4 Solution velocity, m / s 100 100 100 100 Efficiency is inhibited by corrosion of brass during the washing period,% 89.5 92.1 92.1 90.8