Acid-cleaning inhibiter for cleaning boiler and use method thereof

Abstract

The invention discloses an acid-cleaning inhibiter for cleaning a boiler and a use method thereof. The acid-cleaning inhibiter comprises the following components by weight percent: 2.0%-10.0% of acid liquor, 0.08-0.25% of urotropine, 0.04-0.15% of dimethylbenzene thiourea or thiourea, 0.01-0.05% of thiocyanate, 0.03-0.12% of dodecyl-cetyl phenmethyl chloride or bromide, 0.05-0.12% of a surface active agent and the balance of water. Acids suitable for the acid-cleaning inhibiter include hydrochloric acid, citric acid, sulphuric acid, hydrofluoric acid, aminosulfonic acid and phosphoric acid, which are suitable for boiler steel, mild steel, alloy steel and steam steel. The inhibition effect of the invention is over 98% with less toxicity under the boiler chemical cleaning condition, the value of LD50 (orally taken by mice) is 5.74 g / kg. The invention can be stored for 2 years, resistant Fe<3+> ion is 800 mg / kg in the acid cleaning. The preparation method has simple steps, easily obtained raw materials and convention operation.

Description

technical field [0001] The invention belongs to chemical preparations and methods for boiler cleaning, in particular to a pickling corrosion inhibitor for boiler cleaning and a use method thereof. Background technique [0002] In recent years, citric acid pickling corrosion inhibitor is a special corrosion inhibitor urgently needed in the chemical cleaning of large thermal power plants. Shaanxi Chemical Industry Design Institute in China made SH-405 citric acid pickling corrosion inhibitor by using pyrazolone drug by-product FAA colloid, etc. The performance is not stable enough, the shelf life is short, and it has a strong pungent smell. The Lan-826 corrosion inhibitor commonly used in China has precipitated after storage, the corrosion inhibition efficiency has decreased, and its toxicity is relatively high, LD 50 (Mice orally): 1130mg / kg. [0003] Hydrochloric acid has a strong ability to dissolve iron oxides. After pickling, the surface is in good condition without res...

AI Technical Summary

Problems solved by technology

At present, IS-129, a commonly used corrosion inhibitor for hydrochloric acid pickling, has high corrosion inhibition efficiency and moderate toxicity, but there are many foams, which will affect the pickling process in severe cases.

[0004] In addition, sulfamic acid, nitric acid, hydrofluoric acid, phosphoric acid and sulfuric acid are also used in the chemical cleaning of large-scale thermal power plants, especially the pre-furnace systems of some infrastructure units are usually cleaned with citric acid, while the boiler body is often cleaned with hydrochloric acid Cleaning, in the current situation, two different corrosion inhibitors are required, which brings inconvenience to field application