State of the art corrosion inhibitor programs for evaporative cooling systems are based on phosphate, phosphonates, zinc and combinations thereof. Although generally satisfying control of corrosion can be achieved, all programs have drawbacks such as lack of biodegradability and content of heavy metals. Consequently, there is a need for corrosion inhibitors with an improved environmental profile and/or improved performance. This contribution shows the results obtained with a newly developed corrosion inhibitor, phosphorous modified organic acid (PMOA). It is free of heavy metals and has an excellent environmental profile. Corrosion tests have been carried out in dependence of important application parameters, applying electrochemical methods, beaker tests and long term tests in cooling circuit simulating devices. The results show excellent efficiency and significant synergies between the new substance and other inhibitors. Pilot plant studies of a formulation based on the new inhibitor show the same or better performance compared to commercially available products, but a marked reduction of the phosphorous entry into the waste water. The improved performance can be transferred directly into savings. The positive results were confirmed in a cooling water system of a German refinery.
Key words: downloadable, corrosion inhibitor, cooling systems, low-phosphorous, environmental friendly, PMOA