Patent ID: 7179428

Claim:
A fluid catalytic cracking reactor, comprising: an elongated reactor riser having a downstream end outlet positioned within a reactor vessel having a lower end equipped with a catalyst outlet and an upper end equipped with a cracked vapor outlet, wherein the reactor vessel defines a dense phase fluidized stripping zone containing a dense phase fluidized bed of catalyst with an upper bed level, wherein within the reactor vessel is a cyclone separator fluidly connected to the downstream end outlet of the elongated reactor riser, which the cyclone separator is provided with a dipleg having a dipleg diameter (d 1 ) and a lower open end having a restriction defining a restricted opening diameter, wherein the dipleg extends downwardly so that its lower open end terminates below the upper bed level of the dense phase fluidized bed of catalyst, wherein located within the dense phase fluidized stripping zone is a horizontal plate positioned at a distance (d 2 ) below the lower open end of the dipleg, wherein the horizontal plate has a raised border and is defined by a plate diameter (d 3 ), and wherein the plate diameter (d 3 ) of the horizontal plate inclusive of the raised border is between 1.2 and 0.9 times the dipleg diameter (d 1 ).