Total Sulfur Monitoring in Ethylene and Propylene Refining

 

Total Sulfur Monitoring in Ethylene and Propylene Refining

 

One principal activity at most large refineries is the refining of ethylene and propylene from crude oil and its derivatives. Sulfur and sulfur compounds are present to some extent in almost all crude oil reserves in the western hemisphere. Ethylene and propylene are primarily used as raw materials in the manufacturing of plastics, these process streams are sold to chemical processing plants where they are polymerised. 

 

Sulfur compounds poison the polymerization process employed in converting ethylene and propylene to polyethylene and polypropylene respectively. Very expensive catalyst chemicals are destroyed as a result of the poisoning. Because of this, sulfur compounds are scrubbed from ethylene and propylene process streams, normally at the refinery prior to the sale of the processor. Lead Oxide scrubber beds are used as sulfur scavenger. Similar to an automobile catalytic converter, the scrubber bed consists of a large reactor vessel filled with millions of ceramic balls, which are coated with lead oxide.

 

Lead oxide has a tremendous affinity for absorbing many different sulfur compounds but, eventually reaches a saturation point, when the reactivity drops and no more sulfur can be absorbed. When the saturation point is achieved the scrubber must be regenerated. Usually scrubber beds are operated in parallel, enabling one bed to be regenerated while the other remains on-line. Without a sensitive, specific, on-line analyzer. The beds are regenerated every four to seven days as a safeguard. Bringing in a CI Analytics Total Sulfur Analyzer can virtually eliminate the need to perform unnecessary regeneration of the scrubber bed.