Abstract: A downcomer for use in ebullating bed reactors that is perforated along its length within the reactor. These perforations are sized slightly smaller that the solid catalyst particles used in the reactor in order to screen out these solid particles and prevent their flow or movement into the downcomer from the reactor. As a result of the perforated downcomer, any liquid separated from the fluidized medium and collected in the downcomer will flow back through these perforations and into the reactor when the ebullating bed is operating at its normal level; however, when the ebullating bed is operating at an upset level condition, the liquid in this fluidized medium will flow in the opposite direction and will pass through these perforations into the downcomer in order to maintain a minimum flow to the ebullating pumps.

Abstract: A downcomer for use in ebullating bed reactors that is perforated along its length within the reactor. These perforations are sized slightly smaller that the solid catalyst particles used in the reactor in order to screen out these solid particles and prevent their flow or movement into the downcomer from the reactor. As a result of the perforated downcomer, any liquid separated from the fluidized medium and collected in the downcomer will flow back through these perforations and into the reactor when the ebullating bed is operating at its normal level; however, when the ebullating bed is operating at an upset level condition, the liquid in this fluidized medium will flow in the opposite direction and will pass through these perforations into the downcomer in order to maintain a minimum flow to the ebullating pumps.