Abstract
Chlorides are used to enhance the efficiency of reformer catalysts. During the regeneration and reactivation of these catalysts, the hydrogen chloride, water, carbon dioxide and oxygen in the system can cause rapid corrosion of effluent coolers and associated piping. Satisfactory control of these corrosives is obtained by injecting water containing a neutralizer, ahead of the coolers, while monitoring the pH of the water draw. Metal losses have been determined with electrical resistance probes and a microprocessor controlled corrosion rate meter. Attempts to control neutralizer injection by pH alone didn't work as well as the combined pH and corrosion probe measurements. The need for modification of the corrosion control system was disclosed by using both indicators. Metal losses have been reduced from more than 0.38 mm (15 mils) per regeneration and reactivation to less than 0.076 mm (3 mils) metal loss. The number of unscheduled shutdowns in a set of nine units due to corrosion-related causes dropped from as many as thirty-six days in a single year to none in each of the past two years. Modifications to achieve this improvement include better mixing of the injected wash water with the gases, the use of more neutralizer, closer pH control, on line corrosion monitoring and training of personnel.
