Acetic acid is evaporated and
after adding catalyst is passed
through a series of coils placed
in a furnace. The Pyrolysis of
acetic acid takes place in the
coils placed in the furnace and
products of phrolysis are ketene
and water. The reaction can be
represented by
The exit gases from the furnace
i.e. ketene, water, unconverted
acid etc. are immediately cooled
in a series of coolers to
condense water and unconverted
acid. The condensate from these
coolers is sent to acid recovery
section to recover acetic acid.
The ketene gas is scrubbed with
acetic acid in a series of
scrubber towers to produce
acetic anhydride. The reaction
can be represented by the
following equation:
The over flow from the scrubbers
i.e. Crude acetic anhydride
subjected to fractional
distillation to obtain pure
acetic anhydride. The whole
process is carried under reduced
pressure.
