(150b) Multifunctional Coatings to Eliminate Exchanger Fouling and Improve Refinery Output

Fouling management of heat exchangers used in petroleum refining is a source of significant economic loss and carbon emissions. The high level of contaminants contained within crude oil (salt, wax, sand, acid, mud, corrosion products) means that the deposition mechanics can be quite complex, and fouling can be quite rapid, leading to thermal efficiency losses of up to 30% (Nakao, 2017, Costa, 2011). An additional consideration is the wide temperature range of the pre-heat train (PHT), where during the first main step of the refining process, crude oil is heated from transport temperatures of approximately 30°C to temperatures exceeding 400°C, excluding the use of many typical polymeric anti-fouling polymeric materials.

This talk will cover three different sets of “omniphobic”, fouling-resistant surface treatments optimized for different stages of the PHT. These materials all utilize a similar low-surface energy chemistry combined with extremely low finished surface roughness to provide broad repulsion behavior against all the different particulates within the crude oil product. The three materials described here vary predominantly in their compatible temperature ranges: the first, designed primarily for temperatures up to 225°C, has been fully deployed in operational systems, and has demonstrated complete repulsion of adhered fouling for greater than 1 year. The second material, designed for temperatures up to 375°C, has been applied to subscale shell-and-tube heat exchangers on a trial basis on both the interior and exterior. The final material, currently under benchtop evaluation, has shown material durability and adhesion comparable to existing commercially available coatings (following ASTM D3359 and ASTM D4060, respectively), and temperature compatibility up to 550°C.

Simulated exposure testing on all three materials showed compatibility with a broad gamut of typical solvents used in cleaning operations. Utilization of such coatings has suggested the overall lifetime of PHT systems could be increased 2-fold, lowering costs substantially without capital investment or retooling of existing processes.