Heat exchange system having slide bushing for tube expansion

A method for preheating an air stream and burning fuel to form carbon black, comprising the steps of:

• directing the air stream to an air preheater, the preheater having a plurality of tubes and a first, second and third tubesheet disposed in a shell, the shell having an inside diameter;
• means for directing a hot fluid stream from a reactor for forming the carbon black into the tubes, the tubes having an inflow end and an outflow end,
• the first, second and third tubesheet being sealingly attached to the shell, the first and third tubesheet being disposed in proximity to the inflow end and the outflow end of the tubes, respectively, the second tubesheet being disposed therebetween and having means for sliding of the tubes therethrough while providing for leakage and restricting flow between the tubes and the second tubesheet,
• means for directing the air stream into a first compartment in the shell, the first compartment being between the first and second tubesheet and having a volume, then out of the first compartment to a distal end of a second compartment in the shell, the second compartment being between the second and third tubesheet, wherein the air stream can flow countercurrent to the hot fluid stream in the tubes to an outlet from the second compartment in proximity to the second tubesheet;
• and
• conducting the air stream from the preheater to the reactor for forming the carbon black.

A heat exchanger having a plurality of tubes disposed in a shell, comprising:

• means for directing a first fluid steam into the tubes, the tubes having an inflow end and an outflow end and an interior surface, and means for directing a second fluid flowing at a selected flow rate through the shell;
• a plurality of tubesheets sealingly attached to the shell, at least one of the tubesheets being sealingly attached to the tubes;
• and
• a plurality of bushings in at least one of the tubesheets, the bushings being adapted for sliding of the tubes therethrough while providing for leakage and restricting flow between the tubes and the tubesheet to a selected percentage of the selected flow rate through the shell.