METHOD OF CLEANING AND PASSIVATION OF INNER SURFACE OF PIPES WITH SUCCESSIVE ACTION OF CHEMICAL REAGENT AND STEAM-OXYGEN MIXTURE Russian patent published in 2019 - IPC B08B9/27 B08B3/08 F28G9/00 

FIELD: heat power engineering.

SUBSTANCE: invention relates to heat engineering and can be used for cleaning of internal surface of pipes of thermal power plants (TPP) from deposits and for subsequent passivation of this surface. First cleaning medium is obtained by adding sodium hydroxide to hot water to achieve concentration in water of 2.0÷2.2 wt%. Inner surface of the pipes is cleaned with a first cleaning medium with subsequent washing of the internal surface of the pipes with desalinated water. Second cleaning medium is obtained by successively introducing into the hot water and mixing the following components: O(CH₂-CH₂-O)_nCH₂-CH₂-OH), where n=7÷9, until concentration in solution is equal to 0.10÷0.12 wt%; 2-mercaptobenzothiazole to concentration in solution of 0.020÷0.022 wt%; disodium salt of ethylenediamine tetraacetic acid to concentration in solution of 1.5÷1.7 wt%; and citric acid to concentration in solution of 1.5÷1.7 wt%. Inner surface of the pipes is cleaned with a second cleaning medium with subsequent washing of the internal surface of the pipes with desalinated water. Steam-oxygen passivation of internal surface of pipes is performed with dosing into oxygen vapor with concentration of 2.0÷2.2 g/dm³.

EFFECT: possibility of cleaning the inner surface of pipes from oil products, high cleaning capacity of the chemical reagent and high efficiency of passivation of the treated surface.

1 cl, 1 tbl