(30d) Revamp with Koch-Glitsch PRO® Valve Trays Doubles Run Length on Caustic Absorber

There exist numerous accounts in literature on improvements in run length that can be achieved in distillation or absorption columns in fouling service when replacing sieve trays or movable valve trays with fixed valve trays with large valve openings. In this paper a case study is presented where a revamp with PRO^® Valve trays from Koch-Glitsch have been used with good success in severe fouling service.

A newly commissioned olefins plant that catalytically cracked a light Fischer-Tropsch derived olefins stream, was bottlenecked by the run length in the plants’ acid gas removal section. An extensive sampling campaign and lab bench scale work identified Aldol condensation polymerisation to be the root cause of the fouling. Extensive research efforts were directed at reducing the reactive components in the feed gas, and optimising the fouling inhibitor dosing chemicals and rates. These resulted in maximum run lengths of between 450 to 600 days on the caustic absorber before it had to be shut down for cleaning. Replacing the original sieve trays in the column with PRO^® Valve trays increased run length to more than a 1000 days. This study shows that while it is important to understand the fouling chemistry and the additives that can prevent or reduce the fouling rates, of equal importance is the installation of the correct column internals to minimise the inevitable build-up of fouling material.