vacuum-distillation and it's principle. How it is used in petroleum industry.

Vacuum distillation and it's principle.
Comparison of vacuum distillation with fractional distillation

1. Vacuum Distillation

2. Vacuum Distillation Tower
•
t
o further distill high
boiling point materials, reduced pressure is required to prevent thermal cracking
•
T
he process takes
place in one or more vacuum distillation towers.

3. Atmospheric vs. Vacuum
•
T
he principles of vacuum distillation
resemble those of fractional distillation, except that:
•
larger-diameter columns are used to maintain comparable vapor velocities at the reduced pressures, the equipment is also similar
•
T
he internal designs of some vacuum towers are
different in that random packing and demister pads are used instead of trays.

4. In Petroleum Industry
•
V
acuum distillation involves taking the residue produced
in the crude distillation unit and further separating this fraction into lighter fractions:
•
inerts/gas
•
v
acuum gas oil (light, medium and heavy)
•
r
esidue

5. Steam Ejectors
•
s
imple, reliable means of producing
vacuum
•
T
hey have low installed cost as well
•
T
hey are commonly found in process
plants having available steam
•
T
hey provide many years of trouble-free
operation

6. Ejector basics
•
a three-stage ejector system with two surface- contact inter-condensers. motive force is provided by steam jets, which draw vapor from a vessel and through the system. The condensers act to reduce the load on the next ejector.

7. Examples (1)
•
T
riple element first-
stage ejectors for crude vacuum distillation

8. Examples (2)
•
A
first-stage ejector
for a urea plant vacuum system. The ejector includes heat tracing and flushing nozzles to remove solid deposits from ejector internals

9. Examples (3)
•
T
hree large
booster ejectors ready for shipment to a steel mill