Cooling jacket for gasification burner

A feed injector for gasification of a feed stream comprising a slurry of solid carbonaceous fuel, the feed injector comprising:

• a burner and a cooling jacket surrounding the burner;
• wherein the cooling jacket comprises a conical head inner wall, a tip wall, a conical head outer wall, and an internal cone;
• wherein the conical head inner wall is connected to the tip wall at a wall corner, the tip wall is connected to the conical head outer wall, and the internal cone is surrounded by the conical head inner wall, the tip wall, and the conical head outer wall;
• wherein an inner channel comprising a heat transfer fluid inlet is defined by the space between the conical head inner wall and the internal cone;
• wherein a flow recirculation zone is in fluid flow communication with a tip channel and is defined by the space between the conical head inner wall, the tip wall, and the point of the internal cone nearest the wall corner;
• wherein the tip channel in fluid flow communication with the flow recirculation zone is defined by the space between the tip wall and the internal cone;
• wherein an outer channel in fluid flow communication with the tip channel is defined by the space between the conical head outer wall and the internal cone;
• wherein the inner channel has a thickness defined by the distance from the conical head inner wall to the internal cone;
• and
• wherein the ratio of the thickness of the inner channel at the heat transfer fluid inlet to the thickness of the inner channel at the interface with the flow recirculation zone is between 1.5 and 3;
• and
• one or more fins extending partially into the inner channel and/or flow recirculation zone.