Crude Oil Compatibility for Mitigating Organic Fouling and Coking

The recent practice of processing an ever expanding slate of crude oils at refineries is necessary to minimize crude oil cost while still obtaining the desired refinery product mix and qualities. However, this practice puts a refinery at risk to increase greatly the organic fouling of preheat exchangers and the coking of distillation furnace tubes. Fortunately, the cause of such fouling and coking is no longer a mystery [1]. Both are caused by insoluble asphaltenes. The asphaltenes may be insoluble in the crude oil itself (self-incompatible), may become insoluble on blending two or more crude oils (incompatible), or may become insoluble by adsorption on metal surfaces (nearly incompatible). Nevertheless, by running tests on each crude oil to measure the insolubility number and the solubility blending number, the Oil Compatibility Model may be used to predict conservatively which crude oils or crude oil blends will produce insoluble asphaltenes. This enables refineries to mitigate fouling and coking by avoiding self-incompatible crude oils and blends of crude oils that are either incompatible or nearly incompatible. As a result, by including the measurement of the insolubility number and solubility blending number as part of each crude assay, crude blends may still be optimized but constrained to avoid insoluble asphaltenes and thus, organic fouling and coking.

[1] Wiehe, I.A., "Process Chemistry of Petroleum Macromolecules", CRC Press, Boca Raton, FL, 2008.