SU905329A1 - Solution for cleaning thermal utility plant made of carbon steels - Google Patents

Description

(54) SOLUTION FOR CLEANING HEAT AND ENERGY EQUIPMENT FROM CARBON STEELS

The invention relates to the chemical cleaning of metal surfaces from carbon steel, in particular to the cleaning of surfaces. Thermal power equipment. Thermal power equipment is subjected to periodic chemical cleaning. A known equipment cleaning solution containing disodium salt of ethylenediaminetetraacetic acid (triloi B), citric acid and hydrazine hydrate at a pH of 7.0-9.0 solution. The closest to the technical essence to the present invention is a solution containing an ethylene diamine tetraacetic acid avunagric acid salt (Trilon B ), organic acid, for example citric acid as a corrosion inhibitor 2-mercaptobenzothiazole (captax) 21. A disadvantage of using known solutions is the low efficiency of removing iron oxides from metal surfaces coated with oily substances. The purpose of the invention is to improve the quality of cleaning metal surfaces coated with oily contaminants. The goal is achieved by the fact that a solution containing ethylenediaminetetraacetic acid ethanol diamine tetraacetic acid (Trilon B), an organic acid and, as an inhibitor, 2-mercaptobenzothiazole (captax), additionally contains polyacrylamide in the following ratio of components, g / l: ethylenediaminetetraacetra disodium salt ) 0.5-5 Organic acid 0.5-5, 2-Mercaptobenzothiazole (captax) 0.1-0.2 Polyacrylamide 0.005-0.01 Citric acid, lactic, tartaric, maleic, phthalic acid is used as the organic acid. The solution treatment process is carried out at a pH of 2.5-3.5. 390 In a solution of concentration of Trilon B and an organic acid, it is chosen depending on the amount of the iron oxide deposits within the limits indicated above (the thicker the film, the more concentrated the solution). Example 1. The determination of the optimum concentration of polyacrylamides in the solution under laboratory conditions is carried out. In order to find the optimal concentration of polyacrylamia, the concentration of dissolved iron is determined by the concentration of polyacrylamide. Samples of steel 2O, UxDW size mm, having scale and contaminated with conservation oil K-17, GOST 10877-64, are tested. The amount of oily soils is 3 g / m. Five samples are placed in a thermostated glass vessel and 25O ml of an aqueous solution of the following composition is poured: 5 g / l Trilon B, 2 g / l milk acid, O, 2 g / l captax and a certain amount of polyacrylamide solution pH 3, 5i. After holding the samples at 98 ° C for 1 h, the concentration of iron is determined in solution. The results are given in table.1. From tab. I it follows that, when crossactivating polyacrylamide is less than 0.005 g / l and more than 0.01 g / l, the concentration of dissolved iron decreases sharply. Therefore, optimal concentrations are polyacrylamide concentrations of 0.005-0.01 g / l, Example 2. The pH of the solution is determined. As in the first example, the tests were carried out in thermostated glass vessels. They poured 25 mp of an aqueous solution containing 5 g / l of trilon B and 2 g / l of organic acid. In tests, young citric, maleic, phthalic and tartaric acids are used. In the prepared solution, 2OO mg of iron compaction () in the form of a powder are introduced. Iron oxide Péro 0a & n is the most insoluble sables of iron. The solution is then kept at 98 for 2 hours, after which the powder is filtered off from the insoluble portion. The concentration of the dissolved iron is determined in the fi lt waste. These experiments are summarized in table. 2. From table. 2, it follows that all the composites of Chrylon B with organic acids 9 have an accelerated dissolution rate of iron oxides in the range of pH 2, S-3.5, and at pH 2.5 and pH 3.5 the rate of dissolution of iron oxide decreases dramatically. The composition of Trilon B with lactic acid has the highest rate of dissolution. Therefore, in all individual experiments, lactic acid is used together with Trilon B. Example 3. A comparison is made of the efficiency of chemical cleaning of samples from steel 2O about scale and oily contaminants in a known solution and in the one proposed under the conditions of Example 1. The results are given in Table. 3. Visual inspection of samples and data table. 3 shows that the complete dissolution of the iron octal deposits during sample processing and processing of the samples with the solution with polyacrylamide is completed after 9O min. The surface of the surface is completely cleaned of iron oxides. When processing samples of solutions without polacacrylamide, the dissolution of iron oxide deposits does not end after 4 hours of treatment, and iron oxides remain on the surface of the samples. PRI me R 4. Przgod g corrosion tests of carbon dioxide (steel 2 O) in the proposed solution and the solution known. Samples are kept in these solutions at a temperature of 4 hours. The corrosion rate of steel 2O in the proposed solution is 0.6 g / mm-H, i.e. The solution is not Corrosive. The corrosion rate of the same C1 in the well-known pacTBqpe without corrosion inhibitors is 9.1 g / cm t, and with a corrosion inhibitor (captax) -1.1. Thus, the corrosion rate of steel 2O in the proposed solution due to the action of polyacrylamide is less than in the hard solution. The given examples confirm that using the proposed solution for cleaning heat and power equipment does not improve the efficiency of dissolution of iron oxide deposits from metal surfaces covered with oily soils, reduce cleaning time of equipment having an oily surface contamination by about 2-3 times. due to reduced cleaning time, cleaning costs, and reducing corrosive losses during equipment cleaning and, as a result, will allow to extend the life of the equipment equipment.

Concentration polyacryl- ,.

amiaaf g / l

Dissolved iron concentration

23O mg / l

Example

Dairy 3524OO5125205O525O1O7

Maleinov 24031444645342O20395

Phalev 19224О37338135615893

Winna 831322812992779564

Lemon 599615316О1476825

Preloaded solution Trilon B5 Milk 382 525 683 acid Kaptaks Polyacryl Famous solution Trilon B5

89 123 23О 314 375 526

Claims (1)

2 0.2 The claims of the solution for cleaning the heat and power equipment of carbon & steel from carbonaceous steels, sotsderzhaya disodium salt. ethylene cytametracetic acid (tr1H .Table 1 0, OO1 0, OO5 0.01 0.05 0.1 234 849 680 378 373 Tabpntsa2 Table3 581 820 825 826 830 pon B), orgmic acid, for example, limonic acid, and as an inhibitor of 2-mer | t) b “13 aeol (captax), because of the quality of cleaning, 76053298 It contains pottiacryl c at barely-sources of information, oyushim ratio of components, g / l: taken into account during the examination Disodium salt of ethylene cylamine and gram-acetic Copyright Certificate of the USSR acids {Trilon B) 0.5-5.0 sN 283772, cl. C 23 F 14/03, 1964. Organic acid 0.5-5.02. Chemical cleaning of heat and power 2-Mercapgobenzothiazoles equipment. Pot total reaac (captax) 0.1-0.2-Marie Margoon. M., 1969, p. 41, 145 Polyacrylamo. 005-0,010 and 148.