PEFTEC 2017 - Abstract

Abstract Title: A new technique to predict inception of coking at refineries resulting in development of an ASTM method, ASTM D6703
Abstract Type: Poster
Session Choice: Other
Presenter Name: Dr Raj Shah
Co-authors:Mrs Cindy Galdamez
Company/Organisation: Koehler Instrument Company
Country: United States

Abstract Information :

The newly updated Automated Flocculation Titrimeter (AFT) allows users to easily and reliably predict which heavy oils and petroleum residua (including asphalts) can be mixed without causing phase separation or coking. It automates the collection of Heithaus values and predicts flocculation for various crudes.

Often times, refiners cannot predict precisely when coking will occur so they stop processing crudes well short of coke formation. In order to prevent fouling in heavy oil processing equipment, tanks, and transfer lines, they stop processing too soon and reduce the distillate yield.

With the development of the advanced AFT, any refinery using this tool can recover additional distillate without fear of fouling. The AFT allows the user to quickly and easily collect the data needed, and by using the Coking Indexes pioneered by Western Research Institute, one can predict the refinery conditions for coking and stop processing before fouling occurs but not sooner than necessary. This advanced equipment is also capable of reverse titration and can be used for flocculation kinetic studies.

The theory behind the development of this innovative and advanced technique is also discussed in this poster. Petroleum residua consists of ordered structures of associated polar asphaltene complexes that are dispersed in a lower polarity solvent phase by intermediate polarity material commonly referred to as resins. When the residuum is heated to temperatures above 340 degrees Celsius, this suspended structure is systematically and irreversibly destroyed during pyrolysis. A certain amount of pyrolysis typically occurs and can be tolerated in a distillation unit, since there is an induction period prior to the appearance of coke. A common problem in the refining industry is to ascertain how close a pyrolysis system is to forming coke on the coke induction period timeline.

The automated flocculation titrimeter has been developed to perform ASTM D6703, the official test method for automated Heithaus titrimetry. This helps to measure the state of the dispersed particle system described above and calculates predictive parameters for heavy oils. With the advanced development, the AFT can now also be used to provide valuable information about the internal stability of a heavy oil, the proximity of a pyrolyzed oil to coke formation, and to design blending protocols to prevent asphaltene precipitation for oils mixtures, as well as study flocculation kinetics. It is an extremely versatile tool for the petroleum industry in both upstream and downstream operations.