The present invention relates to a method for gas-solid contacting in a bubbling
fluidized bed reactor by:
(a) introducing into a reactor with bed length to bed diameter ratio below
about 5.0, a primary gas consisting essentially of reactant(s) of the reaction
to be carried out in the bed of solid particles through a primary gas distributor
located at the reactor bottom at a superficial gas velocity Up, which
is very close or equivalent to the minimum fluidization velocity Umf,
required for achieving the incipient fluidization of the solid particles in the
bed to obtain an emulsion phase consisting essentially of the solid particles and
the primary gas with little or no formation of gas bubbles to achieve incipient
fluidization or liquid-like behavior of fluidizable solid particles;
(b) forming gas bubbles in the incipiently fluidized bed by introducing
through a secondary gas distributor located immediately above the primary gas distributor
a secondary gas, selected from one of the reactants which is used in excess of
that required for the reaction stoichiometry, steam, an inert or a mixture of two
or more thereof at a superficial gas velocity, Us, which is related
to the superficial velocity of the primary gas such that a ratio of the superficial
velocity of the secondary gas to the superficial velocity of the primary gas Us/Up,
is in the range from about 0.5 to about 10.0, preferably from about 1 to about 5.
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