Char-handling processes in a pyrolysis system

A process to heat a heat transfer medium in a reheater, comprising:

• i) separating a mixed stream comprising the heat transfer medium and char into a plurality of separate streams comprising:
• a) a first stream rich in the heat transfer medium and containing a residual quantity of char;
• and
• b) a second stream comprising char;
• ii) introducing the first stream into a dense bed in a lower portion of the reheater;
• iii) fluidizing said dense bed with at least a primary oxygen-containing regeneration gas stream;
• and
• iv) combusting all or a portion of the char with the primary oxygen-containing regeneration gas stream,
• wherein:
• X) the primary oxygen-containing regeneration gas stream is introduced to the dense bed through an inlet riser in fluid communication with a lower portion of the reheater;
• and
• Y) the second stream is mixed and at least partially combusted with the primary oxygen-containing regeneration gas stream in the inlet riser.

A method, comprising:

• i) separating a mixed stream comprising heat transfer medium and char into a segregated char stream and a char-depleted stream;
• ii) introducing the char-depleted stream to a dense bed of heat transfer medium fluidized by an oxygen-containing fluidization gas, said oxygen-containing fluidization gas introduced into a lower portion of the fluidized dense bed;
• and
• iii) combusting the segregated char stream to heat the lower portion of the fluidized dense bed,
• wherein:
• a) the fluidized dense bed is contained in a reheater;
• b) the oxygen-containing fluidization gas comprises a primary oxidant stream and a secondary oxidant stream;
• and
• c) at least a portion of the segregated char stream is mixed with the primary oxidant stream and at least partially combusted in said primary oxidant stream prior to introduction to the fluidized dense bed.