METHOD OF SCALE REMOVAL AND PROTECTION AGAINST SALT DEPOSIT AND CORROSION Russian patent published in 2008 - IPC C02F5/10 C23F14/02 C02F103/02 

FIELD: chemistry, technological processes.

SUBSTANCE: method includes introduction into system of heat exchangers of washing composition, containing pyrosulfates or inorganic oversulfites, hydrolisable alkaline salts of larch bark tannin, anion-active surface-active substances (SAS), as well as acid and water with the following content of components (wt %): sodium, potassium, ammonium pyrosulfate or sodium, potassium or ammonium oversulfite - 0.9-10; hydrolisable alkaline salts of larch bark tannin 0.5-6; anion-active SAS 0.0015-0.009; HCl - 2.0-8.0; water - remaining part. After carrying out purification with washing composition, inhibiting scale formation and corrosion composition is introduced into heat-exchangers system, which contains following components in ratio (wt %): hydrolisable alkaline salts of larch bark tannin 0.5-2; anion-active SAS 0.0015-0.009; water - remaining part.

EFFECT: low corrosion rate at washing stage, enhancing protective properties of compositions, extension of range of ecologically safe and less expensive inhibiting means.

3 cl, 1 tbl, 6 ex