The process gas is sent to a quench water tower where it is being cooled by direct contact with cooling water. This cooling water is further cooled by cooling tower water in series of Barriquand Platular® easy-to-clean welded plate heat exchangers.
Flow rates are huge and are calling for different units to be installed in parallel.
Four operating units + one stand-by have been installed; each unit has a heat transfer area of 846.64m². Due to the presence of chlorides (CL) in the process gas, Duplex Stainless Steel was selected. As the process gas needs to be further compressed, it is very important to cool this gas at the minimum possible temperature, hence a 2.5°C temperature approach.
Due to the presence in the quench water of around 5% weight of gasoline components in dispersion (aromatics rich) and some coke and tar particles, Free flow channels with a 12mm gap were selected to process the quench water, the flow velocity has been set at 1.1m/s to avoid settling of coke particles.
The access, for cleaning, to the quench water channels is ensured by use of hinged access covers, this means that to open and clean the units, this can be done ‘in situ’ without the need for a crane to remove the unit from its location and bring it to a service centre.
Also, the use of a stand-by unit makes it easy to schedule the maintenance operations at the most convenient time. The wide channel (12mm) is also easy to clean and all particles can be pushed out in record time.
