SU932195A1 - Method of chemical cleaning of hea power equipment - Google Patents

Description

The invention relates to chemical cleaning of metal surfaces, such as heat and power equipment (boilers, thermal power plants, nuclear power plants). A known method of chemical purification of heat and power equipment consists in its washing with aqueous solutions of organic acids in the presence of corrosion inhibitors: captak and alkylaryl ethers of polyethylene glycols (OP-7) 1P. The disadvantage of this method is the high cost and deficiency of the added organic acids: citric, visible, etc. The purpose of the invention is to increase the cleaning efficiency by increasing the dissolution rate of the thin oxide deposits and replacing expensive and scarce organic acids. The goal is achieved by the use of organic alkyl acids with average alkyl hydroxamic acids with carbon numbers from 6 to 9 (C (j-Cg)), and washing is performed at pH 2- and 80-100 ° C for 2-6 hours. with a solution of the following composition, wt.%: Alkylhydroxamic acids (C (j-Cg) and O-3. O Captax 0.005-0.02 Alkylaryl esters of poly (ethylene glycol) (OP-7) 0.05-0.2 To create solution of pI 2- add nitric or sulfuric acid. Medium alkyl hydroxamic acids (C (j-Cg), an obium of the formula RC NH-OH, will contain the technical preparation Reagent IM-50, used for the fleet beats of various metals. The high cleaning efficiency of metallic surfaces from iron oxide otlonations is due to the high strength of the resulting complex compounds of iron with alkyl hydroxamic acids. The stability constants of iron complexes (tji) with alkyl hydroxamic acids are within 30.2 - chemical purification using the IM-50 Reagent, laboratory experiments were conducted to study the dissolution of iron oxide d-Feq Oj as the most difficult to dissolve oxide from occurring in the composition of iron oxide deposits. The experimental procedure is as follows. Suspension of iron oxide (analytical grade) 200 mg, with a particle size of 40-5 μm. Concentration Reagent IM-50, weight. 0.3 0.7 The concentration of dissolved 0.5 1.0 iron, mg / l. From table 1 it can be seen that the optimal concentration of the IM-50 Reagent is 1.0-3.0%. Specifically, the concentration of the reagent is selected depending on the amount of 5% oxide deposits on the unwinding surface. Table 2 shows the dependence of the concentration of dissolved iron on the pH of the solution at 1 2 h, the concentration of the IM-50 Reagent is 1.5. 0 Table 2

Table 1-4 is introduced into a temperature-controlled glass vessel containing 25 ml of an IM-50 Reagent solution (or adipic acid). Preliminary experiments established that the rate of mixing does not affect the rate of dissolution of iron oxide, i.e. dissolution occurs in the kinematic mode. The concentration of iron in the samples of the filtrate taken at regular intervals is determined by the colorimetric method on a FEC-M photocolorimeter. Table 1 shows the dependence of the concentration of dissolved iron on the concentration of the IM-50 Reagent at - t 98C. , L- 2 hours. 1.0 1.5 2.0 3.0 3.0 4.0 12.3 21.5 29.7 1.7 h1.9 Continuation tab. 2

Table 2 shows that the optimum is

Table 3 shows the dependence

the concentration of dissolved iron from the solution temperature at a concentration of Reagent IM-50 -, Y4 2 h ,, 0.

Solution temperature, ° С 20

i | 0

Dissolved iron concentration, mg / l 0.1

1.1

From Table 3 it can be seen that the optimum temperature of the cleaning process is in the range of 80-100 ° C.

The duration of chemical purification depends on the ratio of iron oxides: hematite (ot-Fe (jp) and mag0, 25

0.5

one

2

3

6

8 10

Depending on the ratio of oxides on the metal to be cleaned; This chemical cleaning is carried out within 2-6 hours.

The use of the proposed chemical cleaning method makes it possible to increase the cleaning efficiency by increasing the dissolution rate of iron-cleaning deposits and to replace expensive and scarce organic acids. .

invention formula

The method of chemical cleaning of heat and power equipment, table 3

60 70

80

90,100 110

120

2.5 7.9 17.5 19.8 21.717.7 15,

netita () - on the surface being cleaned.

In tab. shows the dependence of the concentration of dissolved iron on the time of dissolution of iron oxides at a concentration of Reagent IM-50 - .U5%. ,, 0.

Table C

60.7 152.3 ZZ, 521.3 520.7 523.3 521.9 522.5 523.2

In its washing with aqueous solutions of organic acids in the presence of captax and alkylaryl ethers of polyethylene glycols, it is characterized in that alkyl hydroxamic acids are used as organic acids and washing is performed at and at a temperature of 80-100 ° C for 2-6 h with a solution of the following composition; wt.% Alkylhydroxamic acids (Cfe-Cg) 1.0-3.0 Captax. - 0.005-0.02

7932195. eight

Alkylaryl ethers1, Margulova T.H. Chemical

polyethylene glycols 0.05-0.2 purification of heat and power equipment; Information sources, adding. M., Energie, 1978 taken into account in the examination of p. 9-10,

Claims (1)

Claim The method of chemical cleaning of heat power equipment, which consists in washing it with aqueous solutions of organic acids in the presence of captax and alkylaryl ethers. Polyethylene glycols, characterized in that, in order to increase the efficiency of cleaning, alkyl hydroxamic acids are used as organic acids, and washing is carried out at pH = 2- 4 and a temperature of 80-100 C for 2-6 hours with a solution of the following composition wt.% Alkylhydroxamic acids (C _fe -Cg) 1.0-3.0 Kaptax 0.005 “0.02 Alkyl aryl ethers of polyethylene glycols 0.05-0.2