Apparatus and method for hydroconversion

A grid plate assembly for use in a hydroconversion reactor, comprising:

• a grid plate having a top and a bottom dividing the hydroconversion reactor into a zone above the grid plate top and a zone below the grid plate bottom;
• a plurality of tubular risers extending through the grid plate;
• wherein each tubular riser comprises an upper section extending above the grid plate top and closed with a bubble cap and a lower section extending below the grid plate bottom and having an open end, at least one laterally placed vertical slot and at least one laterally placed opening,
• wherein the at least one laterally placed vertical slot and the at least one laterally placed opening in each tubular riser are positioned at variable distances from the grid plate bottom such that an inclined liquid level in the zone below the grid plate bottom is maintained between the laterally placed vertical slot and the at least one laterally placed opening,
• wherein the at least one laterally placed vertical slot extends from the open end of the lower section for a length ranging from ⅛ to ½ of the length of the lower section, and
• wherein the laterally placed opening is located from 1 to 5″ below the grid plate bottom with a shortest dimension ranging from 1/16 to ½ of a diameter of the open bottom end of the tubular riser.