Kellogg offers fractionation technology

M.W. Kellogg Ltd., London, has begun offering licenses for its Divided Wall Column (KDWC) distillation technology, proven at a BP Oil Ltd. refinery in the U.K.

Kellogg claims KDWC provides a significant increase in fractionation performance at a lower capital cost than conventional column designs, and that its first application at BP's Coryton refinery proved it.

In April, BP and Kellogg commissioned the first KDWC unit at Coryton, following the revamping of an existing stabilizer column. The payback time for the investment is expected to be less than 1 year.

Kellogg says the divided wall column is more thermodynamically efficient than most simple or complex column alternatives because it minimizes the undesirable remixing of components. The improved efficiency can lead to energy savings, capacity increase, or yield improvements. Kellogg says that KDWC can be retrofitted easily to existing columns, and at Coryton, it doubled throughput capacity and increased the yield of middle distillatse by more than 50%.

How it works

KDWCs comprise two main sections: a prefractionator and a main column. The prefractionator column separates the light components of the feed from the heavy ones, with the middle boiling components split between the two streams.

The rest of the fractionation process takes place in the main column: The top two sections of the main column separate the light components from the middle boilers; the bottom two sections separate the heavy components from middle boilers.

"The prefractionator," said Kellogg, "reduces the amount of heavy components that would reach the top sections of the main column. Also, it minimizes the amount of light components at the lowest sections of the main column and hence provides a better fractionation between components."

Research into divided wall column technology began at the University of Manchester Institute of Science & Technology (Umist) in 1989, under a project in which Kellogg was a participant. The Umist work culminated in construction of a pilot plant, after which Kellogg remained involved by identifying applications and carrying out case studies. The technology was developed and commercialized jointly with BP.

Kellogg said KDWC technology is equally suitable for grassroots and revamp designs and can be applied to a wide range of fractionation tasks: "Beneficial applications have been identified in refining, petrochemicals, and gas processing industries."