A sour-water stripper (SWS) plant at an oil refinery in Europe has installed two Alfa Laval Compabloc heat exchangers because of their special characteristics.

The Compabloc treats and eliminates the residues (H2S and ammonia) present in the water that has been processed at the various plants within the refinery so the water can be reintroduced into the cycle. The perfect function of the SWS plant is of fundamental importance for the refinery: if it stops, all other units also must be stopped.

An advantage of the Compabloc exchanger is the absence of gaskets between the plates, which makes the unit perfect for chemically aggressive environments and for the handling of high temperature and dirty fluids, according to Alfa Laval, Richmond, Va. The construction also means it can run for months without the need to be stopped for cleaning, and when maintenance is needed, it takes half the time compared to a traditional unit. The heat exchanger serves as a feed/bottom interchanger, recovering heat between the bottom and the feed of the stripping column, saving energy.

The refinery selected the Compabloc welded-plate heat exchanger over a traditional shell-and-tube heat exchanger because it is compact, allowing the plant the room to have two units rather than one in the same space. When maintenance is needed, the plant can switch from one unit to the other without costly product stops.

Welded heat exchangers also have a higher thermal efficiency and are easier to clean than shell and tubes, according to Alfa Laval. Coking plants dirty more than many other industrial plants, so ease of maintenance becomes an important factor.

Alfa Laval has since received an order from the same refinery for six additional Compabloc units as reboilers for the revamping of the entire SWS plant.