BTX: Problem and solution - Conclusion: CBUs eliminate BTX-induced catalyst deactivation

Saudi Aramco has installed seven BTX (xylene) removal units using regenerable activated carbon beds commissioned in 2006 in order to combat problems relating to chronic Claus deactivation for years as a result of benzene, toluene and BTX (xylene). The installation virtually eliminated catalyst deactivation. The carbon beds need to be cooled down as well as dried after regeneration before bringing them online because it was showed that it is possible to achieve substantially complete removal of the toluene and xylene. The elimination of the cooling and drying step from the regeneration sequence produced substantial cost savings to the project. It also eliminated the requirement for a drying gas cooler, separator and recompressor as well as the reduction of the amount of carbon installed since the regeneration step is now shorter. All of the vessels within the carbon-bed unit (CBU) are made of 316 L stainless steel. The magnitude of disturbances to the SRU during switchover has also been reduced. The benzene removal also overtook 80% even during the early phase of the adsorption cycle considering the fact that the beds are not being dried and cooled as part of the regeneration step.