Catalytic conversion of gas or liquid in a miltitube reactor

An apparatus for performing a process for catalytic conversion in a multitube reactor, which reactor comprises a normally substantially vertically extending vessel having a longitudinally extending axis, a plurality of reactor tubes arranged in the vessel substantially parallel to said central longitudinal axis, the reactor tubes having upper ends fixed to an upper tube plate and in fluid communication with a fluid inlet chamber above the upper tube plate, the reactor tubes having lower ends fixed to a lower tube plate and in fluid communication with an effluent collecting chamber below the lower tube plate, a means for passing heat-exchange fluid along the outer surfaces of the reactor tubes, an effluent outlet arranged in the effluent collecting chamber, a gas inlet arranged in the fluid inlet chamber, a liquid distributor in the fluid inlet chamber which includes a plurality of adjacent, removable, substantially horizontal trays having flat bottoms and raised edges, which substantially horizontal trays are provided with a plurality of downcomers extending through the bottom of the tray in fluid communication with the upper ends of the reactor tubes, and a liquid supply means for supplying liquid to the substantially horizontal trays.