Rütgers is one of the world’s leading producers of high-quality coal tar oil. When expanding its Castrop-Rauxel depot with new storage capacity the company needed to invest in a cooling solution for the new tanks.
The tanks are filled with batches of oil, which are cooled from 135°C (275°F) to 75°C (167°F) before shipping. The temperature and pressure in the heat exchangers varies over time, causing material fatigue and increasing the risk for unplanned downtime.
The duty is also characterized by fouling, and it is important to choose a heat exchanger with good resistance to fouling for this position to minimize time and cost for cleaning.
Alfa Laval offered Rütgers a complete cooling solution where the coal tar oil is cooled by two Alfa Laval DuroShell plate-and-shell heat exchangers. The cooling medium from the DuroShells is in turn cooled by two Alfa Laval ACHE air-cooled heat exchangers.
Alfa Laval DuroShell is specifically designed for duties where metal fatigue is a problem and was a perfect choice for Rütgers. Thanks to its unique plate pattern, inlet and outlet pipes that traverse the entire plate pack, and laser-welded plates, DuroShell offers much better fatigue resistance than shell-and-tube and conventional plate and-shell heat exchangers.
The ability to operate with crossing temperatures and the small temperature approach make DuroShell highly efficient in cooling duties. For Rütgers this means the cooling medium can be better utilized, with lower costs for piping and pumps as a result, as well as lower costs for pumping the cooling medium.
Apart from the excellent cooling capacity, we were really impressed by the minimal maintenance needed. The special plate pattern prevents fouling and all we need do to clean the DuroShell is to flush it through.
Dietmar Scholl, operations technical officer at the Rütgers Group