Fluid Catalytic Cracking Video Lecture | Chemical Technology - Chemical Engineering

PRESENTER: Fluid catalytic
cracking, or FCC,
is the last step in
the evolution of cat
cracking processes--
also introduced in 1942,
just like TCC or Thermafor
Cat Cracking, during
the Second World War
in an effort to make
high-octane number gasoline.
Remember that high-octane
number relates to high power
as you can have higher
compression ratios
in the combustion engines.
FCC really shows an
excellent integration
of the cracking reactor,
an endothermic reactor,
with the catalyst regenerator
and exothermic reactor for very
high thermal efficiency.
FCC is now used universally
in oil refineries
throughout the world--
has replaced all the previous
cat cracking processes.
Now, in FCC, in
the feed, that is
gas oil preheated to about
300 degrees Fahrenheit--
is introduced into the
reactor with steam.
The riser part of the reactor
where the hot catalyst
particles-- as you see,
the green line coming from
the catalyst regenerator--
are full of dyes.
The particles are full
of dyes because they're
smaller particles.
They are full of dyes and
flowing gases and vapors.
So they have a huge surface
area to meet the incoming feed
at temperatures that are close
to 1,000 degrees Fahrenheit.
So cracking reactions on
these very fine particles that
are full of dyes and
flowing with the reactants
takes place in a very short
space of time, something that
could be measured with seconds.
And the products are
sent to a fractionator
after going through
a series of cyclones,
obviously, to separate
the small fluid dyes,
the particles of the catalyst.
In the fractionators,
the products, as usual,
are separated into gas,
gasoline, light cycle
oil, heavy cycle oil,
and, finally, the heaviest
fractions, decant oil.
Remember that LCO
is used in the US
for making diesel fuel
through hydrocracking
and hydrogenation.
And decant oil could be used
as fuel oil or as feedstock
for making carbon black or
white coking to make needle
coke for graphites, electrodes.
Coming back to the reactors,
the cat cracking reactor,
the coked catalyst now,
the end of the riser where
this cracking
reaction takes place,
are sent through
the regenerator.
It's not fully coked on the
surface, lost its activity.
Through the red line, it's
sent to the regenerator
where air is introduced
to burn off the coke.
The temperatures
in the regenerator
could reach to 1,300 to
1,400 degrees Fahrenheit.
You should remember
that the catalysts now
are much improved, as well.
It may include
zeolites that would
take high temperatures and
very controlled reactivities
through pore size
distribution and so forth.
So the combustion
products or flue gases
from this catalyst regenerator
could be sent to a CO boiler
because the gas may contain
significant amount of carbon
monoxide, which could be
burned to CO2 to provide
additional heat or to
generate additional heat.
So the catalysts that
are now regenerated
are sent to the reactor to
close the catalyst cycle
through that green line, as you
see, to meet the incoming feed.
So our catalyst cycle is pretty
much complete at this point.
But note this
excellent integration,
thermal integration, of
the catalyst regeneration,
the exothermic process,
with the cracking reactions
where the catalysts that are
heated in the regenerator
are sent in a very effective
manner to the reactor
without much heat loss.
So that is the ultimate, if
you will, thermal efficiency
of a process.
And that's why FCC is now
the universally accepted
catalytic cracking process.