Hydrogen fluoride-catalyzed alkylation apparatus

An alkylating apparatus comprising a first reactor and a first settler communicating therewith, a second reactor, a second settler communicating with the second reactor, means for passing liquid from the upper portion of the first settler to the second reactor, a first catalyst recirculating conduit between said first settler and said first reactor, a second catalyst recirculating conduit between said second settler and said second reactor, an eductor, first conduit means connecting said first recirculating conduit with the inlet end of said eductor, second conduit means connecting the outlet end of the eductor with said second recirculating conduit, an additional conduit connecting said second conduit means with said first conduit means, and a separate conduit connecting said second conduit means with said first conduit means, whereby said additional conduit and said separate conduit provide means by which catalyst may be moved from said first catalyst recirculating conduit to said second catalyst recirculating conduit, or vice-versa, to enable selective adjustment of the catalyst inventory in the first and second reactor-settler circuits.