51313-02756-New Corrosion Inhibitors for Evaporative Cooling Systems

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Product Number: 51313-02756-SG

ISBN: 02756 2013 CP

Author: Wolfgang Hater

Publication Date: 2013

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Corrosion of heat exchangers and installations in evaporative cooling systems is a serious problem of industry as it may lead to increased maintenance effort damages up to plant shut-down causing high cost. Furthermore there may be a high environmental impact due to the discharge of blow-down water containing heavy metals or hazardous compounds which may enter the water system via leakages.

State of the art corrosion inhibitor programs are based on phosphate phosphonates zinc and combinations thereof. Although generally satisfying control of corrosion can be achieved all programs suffer more or less severe drawbacks such as lack of biodegradability content of heavy metals or necessity of pH control combined with acid dosage.

Consequently there is a need of corrosion inhibitors having an improved environmental profile and/or an improved performance. This papers shows the first results of two newly developed corrosion inhibitors. Both molecules are free of metals one additionally doesn’t contain phosphorous.

Corrosion tests have been carried out with carbon steel specimen in dependence of inhibitor concentration water composition and water temperature. Electrochemical methods e.g. voltammetrie and polarization resistance were applied as well as beaker tests and long term tests in cooling circuit simulating devices. Furthermore the anti-scaling efficiency of the new inhibitors was studied.

The results of the corrosion tests clearly show an excellent efficiency of both substances that meets the performance of commercially available corrosion inhibitors. In addition to this the phosphorous containing molecule shows a very good inhibition of calcium carbonate scaling similar or even better compared to the performance of modern polycarboxylates. Thus it could be the backbone of a complete treatment program for cooling systems. The second corrosion inhibitor could be applied in phosphorous and heavy metal free corrosion inhibition programs.