Q & A > Question Details
How is 'COS' formed in FCCU riser-reactor section and what are the measures necessary to minimize its concentration to avoid slippage of 'COS' into product LPG/Propylene?
09/03/2016 A: Chayan Bhalla, Mangalore Refinery and Petrochemicals Ltd, chayan.bhalla@gmail.com
COS is formed in FCC reactor riser as a result of the hydrolysis reaction between H2S and CO2 thus forming COS and H2O. While there is not COS related specification for LPG , the concentration in propylene can be minimized by the use of nitrogen regenerable catalyst beds. There are specialist vendors readily offering the technology. The beds are usually regenerated with hot nitrogen (around 290 deg C) and replaced every 4-5 years.
24/02/2016 A: Sridhar Balakrishnan, Bharat Oman Refineries Limited , laksrid@yahoo.com
Carbonyl Sulphide is produced during the hydrocarbon cracking reaction in FCC units. Carbonyl Sulphide boils lesser than propane around minus -50°C . Removal of carbonyl sulphide is done by secondary treating units supplied by well known Technology Suppliers.
22/02/2016 A: Eric Hennings, Technip Stone & Webster, EHennings@technip.com
COS is formed from reaction of CO2 with H2S. There are amines which are selective in absorbing COS.
Best practice in petrochemical process is to install a regenerable absorbent bed to remove remaining COS.
03/09/2015 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
In general, the higher the ROT, the higher the COS production. It is uneconomical to reduce ROT to reduce COS. Better to have a COS removal step in the treating unit. It is essential if propylene is recovered and sold.