How to choose commonly used boiler cleaning agents

1、 Pickling agent

Suitable acid pickling agents and solubilizers should be selected for different types of scale and metal materials, generally as follows:

1) For iron oxide scale, fluoride can be added to hydrochloric acid or nitric acid can be used for cleaning;

2) For silicate scale, fluoride (such as hydrofluoric acid, sodium fluoride, ammonium hydrogen fluoride, etc.) can be added to hydrochloric acid for cleaning;

3) For sulfate scale or mixed sulfate and silicate scale, it should be transformed by alkaline boiling in advance, and then cleaned with hydrochloric acid or hydrochloric acid added with fluoride;

4) For carbonate scale, hydrochloric acid is generally used for cleaning;

5) When copper is present in the scale sample, additives to prevent copper plating should be added to the cleaning solution. Generally, hydrochloric acid with thiourea and fluoride additives can be used, or after acid washing, copper can be removed by cleaning with ammonia water and ammonium persulfate;

6) Boilers made of austenitic steel materials are prohibited from being cleaned with hydrochloric acid. Generally, EDTA, amino sulfonic acid, citric acid, formic acid, acetic acid, hydroxyacetic acid, and other cleaning agents can be used. At the same time, corrosion inhibitors and additives should not contain halogen elements.

2、 Alkali detergent

Alkaline cleaning agents are commonly used for passivation of newly built boilers, alkaline cleaning or scaling transformation in boiler acid washing processes, and alkaline cleaning agents for small-scale boilers. The commonly used alkaline cleaning agents are as follows:

1) When operating a boiler to remove sulfate and silicate scales, alkaline boiling transformation is required before acid washing. The alkaline boiling solution is generally composed of trisodium phosphate and sodium carbonate, or trisodium phosphate and sodium hydroxide, as well as surfactants and other additives.

2) When a new boiler is subjected to alkaline boiling or acid washing before alkaline washing, the alkaline washing solution is generally composed of sodium hydroxide and trisodium phosphate, or trisodium phosphate and disodium hydrogen phosphate, as well as wetting agents and other additives. High pressure boilers or boilers made of austenitic steel materials should not use sodium hydroxide as the main alkaline detergent.