Methods and apparatus for enhanced gas distribution

A system for at least partially oxidizing an oxidizable compound by contacting at least a portion of said oxidizable compound with a gas-phase oxidant in a reaction medium, said system comprising:

• a first oxidation reactor;
• a second oxidation reactor in downstream fluid-flow communication with said first oxidation reactor;
• a bubble column actor in downstream fluid-flow communication with said second oxidation reactor and defining a reaction zone;
• and
• a sparger disposed within said reaction zone and configured to discharge at least a portion of said gas-phase oxidant into said reaction zone,
• wherein said sparger comprises one or more fluid distribution conduits defining a plurality of fluid discharge openings, wherein said sparger is disposed within the normally-lowermost 30 percent region of said reaction zone;
• an outlet for a reaction medium, wherein the outlet for the reaction medium is located at or near a normally bottom portion of the bubble column reactor, below the sparger;
• a gas outlet at or near a normally top portion of the bubble column reactor;
• wherein said bubble column reactor is configured to receive the reaction medium in the form of a slurry from said second oxidation reactor within the normally-uppermost 50 percent region of said reaction zone and at a position below a surface of the reaction medium;
• wherein when said sparger is theoretically partitioned into four annular regions of equal area, the cumulative discharge opening area of the fluid discharge openings located in one of said annular regions is within 25 percent of the cumulative discharge opening area of the fluid discharge openings located in at least one other of said annular regions,
• wherein said sparger has a total flow-through open area of at least 25 percent;
• wherein said sparger has a maximum diameter that is at least 90 percent of the diameter of said reaction zone at the elevation where said sparger is disposed;
• and
• wherein said sparger is configured such that agitation of the reaction medium is provided primarily by upward movement of gas bubbles discharged from said at least three fluid discharge openings through said reaction medium, such that less than 5 percent of the agitation of the reaction medium is provided by mechanical agitation.