Hydroprocessing reactor with extended operating life

A reactor for reacting a two-phase, gas and liquid mixture in a fixed bed of solids, comprising:

• a vessel;
• means to introduce both liquid and gas into said vessel and means to remove both liquid and gas from said vessel;
• a flow distributor tray disposed adjacent the liquid and gas introduction means;
• at least one main bed of solids disposed in said vessel;
• and
• an auxiliary bed disposed above said main bed below said flow distributor tray having at least one gas bypass means for passing gas therethrough when said auxiliary bed becomes fouled, said gas bypass means comprising a hollow unobstructed open tube extending through said auxiliary bed and flow distributor tray to terminate at its uppermost end above the normal liquid level on said flow distributor tray, said unobstructed open tube having a gas flow resistance sufficient to act as a substantial gas seal against the passage of gas through said bypass means when said auxiliary bed is not fouled and to provide a low pressure drop bypass for said gas flowing to said main bed when said auxiliary bed becomes fouled, and at least one liquid bypass means for passing liquid through said auxiliary bed when said bed becomes fouled, said liquid bypass means comprising a hollow unobstructed open tube extending through said auxiliary bed and attached at its upper end to said flow distributor tray in fluid communication with liquid on said distributor tray, said liquid bypass means open tube having a liquid flow resistance sufficient to act as a substantial liquid seal against the passage of liquid through said liquid bypass means when said auxiliary bed is not fouled and to provide a low pressure drop bypass for said liquid flowing to said main bed when said auxiliary bed becomes fouled.