Examination of a "Green" corrosion inhibitor and corrosion resistant alloys for the overhead of the crude oil distillation unit

The aim of this work is to examine a new "green" corrosion inhibitor and nine different alloys for use in the overhead of the crude oil distillation unit. Ammonia, organic amines, amides, and imidazolines are injected in the overhead. In order to avoid using unfriendly ammonia, a new "green" corrosion inhibitor was examined in a model aggressive solution (pH=3.2) during a distillation procedure under laboratory conditions and showed 87-93% efficiency at concentrations of 30-40 ppm. This new inhibitor was compared with two commercial inhibitor systems, and revealed similar efficiency, but its benefit is that it does not contain ammonia. Six stainless steels, nickel-molybdenum alloy, titanium, and brass were examined in the model aggressive solution (pH=3.2) as above. High corrosion rates were found for carbon steel (2.4 mm/year) and brass (2.1 mm/year). Other alloys showed very low corrosion rates (< 0.13 mm/year) and were recommended for use as materials in the overhead. Air cooler and heat exchanger tubes made from titanium have been used for 18 years in the oil refinery with success.