Inhibition of corrosion in aqueous systems

Abstract

The present invention provides an effective method of inhibiting corrosion on metallic surfaces in contact with a fluid contained in an industrial fluid system, which includes adding to such fluid an effective corrosion controlling amount of a particular generally recognized as safe (GRAS) compound.

Description

FIELD OF THE INVENTION [0001] The present invention relates generally to the protection of metallic surfaces from corrosion in both the vapor and liquid phases of aqueous and non-aqueous fluid systems. More specifically, the present invention relates to corrosion inhibiting compositions and methods of using the same. BACKGROUND OF THE INVENTION [0002] Corrosion of metallic components in plants may cause system failures and sometimes plant shutdowns. In addition, corrosion products accumulated on the metal surface will decrease the rate of heat transfer between the metal surface and the water or other fluid media, and therefore corrosion will reduce the efficiency of the system operation. Therefore, corrosion can increase maintenance and production costs. [0003] The most common way to combat corrosion is to add corrosion inhibiting additives to the fluid of such systems. However, many currently available corrosion inhibiting additives are either non-biodegradable, toxic, or both, whi...

AI Technical Summary

Benefits of technology

[0016] The present invention provides an effective method of inhibiting corrosion on metallic surfaces in contact with a fluid contained in an industrial fluid system, which comprises adding to such fluid an effective corrosion controlling amount of a generally recognized as safe (GRAS) compound. The GRAS compound may be, e.g., an acyloin or alpha-hydroxyketone, riboflavin (also known as Vitamin B2, flavin, lactoflavine, ovoflavin or 7,8-dimethyl-10-ribitylisoalloxazine), diallyl disulfide (a component of garlic and garlic oil) or cysteine.

[0017] In a preferred embodiment of the invention, the compound is diallyl disulfide. The acyloin compound may be, e.g., acetoin, or 3-hydroxy-2-butanone. The acetoin compound and its oxidation product, 2,3-butanedione, are both GRAS-listed chemicals. Riboflavin, diallyl disulfide and cysteine are also GRAS-listed chemicals. This classification makes the materials more readily acceptable for their use as metal corrosion inhibitors in food industry applications.

Problems solved by technology

Corrosion of metallic components in plants may cause system failures and sometimes plant shutdowns.

In addition, corrosion products accumulated on the metal surface will decrease the rate of heat transfer between the metal surface and the water or other fluid media, and therefore corrosion will reduce the efficiency of the system operation.

Therefore, corrosion can increase maintenance and production costs.

However, many currently available corrosion inhibiting additives are either non-biodegradable, toxic, or both, which limits the applicability of such additives.

While amines and combinations of amines generally provide effective protection against the corrosion of steel and other ferrous-containing metals, the use of amines in anti-corrosion additives presents several problems.

First, amines often undergo thermal decomposition at high temperatures and form ammonia, which can be very corrosive to copper and copper alloys, especially in the presence of oxygen.

Thus, amine-containing corrosion inhibitors are often unsatisfactory for use in systems containing copper or copper alloy metallurgies.

Further, in a number of applications including food processing, beverage production, co-generation plants, and pharmaceutical manufacturing, the use of amines is limited due to governmental regulations or concerns for taste and odor problems.

Consequently, in many of these applications, no anti-corrosion treatment program is used at all.

Therefore, these systems are susceptible to high corrosion rates, significant maintenance costs and high equipment failure rates.

The surfactants were found to be ineffective as corrosion inhibitors.