Development of an Automated Flocculation Titrimeter (AFT) to predict coking tendencies in refinery crude mixtures through colloidal stability quantification
Dr. Raj Shah - Koehler Instrument Company, Inc.
- Stanley Zhang - Koehler Instrument Company, Inc.
- Stefan Lim - Koehler Instrument Company, Inc.
- William Monsees - Koehler Instrument Company, Inc.
Flocculation is defined as the process of aggregation and coalescence into a flocculent, or clumped, mass. This term is commonly used when discussing the colloidal stability of asphalts, particularly in ASTM D6703, which is the standard test method for automated Heithaus titrimetry. Bituminous asphalts and heavy oil residues can be modelled as colloidal suspension, where the dispersed phase is the polar associated asphaltene moiety and the dispersing medium is the maltene solvent moiety. The flocculation point is determined spectroscopically, as the sample is titrated with isooctane. Newly developed Automated Flocculation Titrimeters (AFT) automate the determination of Heithaus values and can predict flocculation tendencies for various crude and oil samples, all while conforming to ASTM D6703. These AFT instruments can reliably predict which asphalts, petroleum residues, and heavy oils can be mixed without phase separation occurring. This can be utilized by refiners by using the Coking Indexes developed by Western Research Instituted, so a refinery can predict the refinery conditions that result in undesirable coke formation. This poster will discuss the theory of operation and design of the AFT instrument, and how AFT can be applied to an industrial refinery to help improve distillate yields.