Appeal No. 96-0112
Application 07/877,913
by the examiner at page 3 of the Answer, Owen discloses (column 3, lines 42-45) that:
In many FCC units better feed vaporization is achieved by using a higher
temperature in the base of the riser reactor, and quenching the middle of the riser or the
riser outlet.
In contrast to appellants’ argument, this statement is more than mere “dicta”. It specifically teaches that
employing a higher temperature in the base of a riser reactor followed by quenching at the middle of the
riser reactor (50 % of the riser reactor length from the base of the riser reactor) enhances feed
vaporization in many fluidized catalytic cracking processes. Inasmuch as this approach is one of the
known methods for improving a catalytic cracking process, a person having ordinary skill in the art
would have been led to employ a higher temperature in the base of a riser reactor, together with
quenching at the middle of the riser reactor, with a reasonable expectation of improving hydrocarbon
feed vaporization in a catalytic cracking process. This is especially true in this situation since the
quenching location is a function of a desired reaction residence time (desired cracking time), i.e., a
function of the desired product (products cracked to a desired level).
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