Transcript Refinery Processes - پایگاه اطلاع رسانی

Refinery Processes
Muhammad Fahad Ansari
Raw Material
• Crude Oil is the raw material for any
refinery.
• In Pakistan ratio of imported Crude &
local crude is 85% & 15%
respectively.
Refinery Processes
• Because of wide differences in crude
oils , we find number of different
Refinery Processes methods
• The most important method of
separating petroleum products is
Distillation .
Distillation
• In this process, the crude oil is heated to
above 400 OC to vapourize. The resulting
vapours are then carried to a fractional
column, having different temperature
zones i-e. fractional column is divided into
several compartments, each compartment
has a specific range of temperature. As
the petroleum vapours ascent the column,
cont….
several fractions
condense & separate in
these compartments.
More than 500
hydrocarbons are
separated from crude oil.
The lighter molecules
comes off at the top of
the distillation column,
the heavier at the
bottom.
Fraction
Boiling
Range (oC)
Number of
Carbon
Atoms
natural gas
< 20
C1 to C4
petroleum ether
20 - 60
C5 to C6
gasoline
40 - 200
C5 to C12
kerosene
150 - 260
C12 to C13
fuel oils
> 260
C14 to C19
lubricants
> 400
C20 and above
asphalt or
coke
Residue
polycyclic
Cracking
• Cracking is a process in which heavy-molecular
weight hydrocarbons are broken up into light
hydrocarbon molecules by the application of heat
and pressure, with or without the use of catalysts,
to derive a variety of fuel products. Cracking is
one of the principal ways in which crude oil is
converted into useful fuels such as motor
gasoline, jet fuel, and home heating oil.
Example
C16H34
C8H18+C8H16
• Molecule with 16 carbon atoms
cannot be used as gasoline but
molecule with 8 carbon atom can.
Coking
• The coking process is very similar to an extreme case of
cracking where one of the end products is coke
• Heavy residual products which accumulate at the base of
the fractionation tower have become more of a problem for
petroleum refneries.
• This is primarily due to the decrease in demand for heavy
residual fuels.
Dewaxing
• Petroleum dewaxing is used to
extract high molecular weight
components, often referred to as
waxes, from a petroleum stream.
These impurities cause petroleum
products to gel or solidify at higher
temperatures.
• Gases such as propane are useful as
dewaxing agents. When propane is
injected into the fluid stream it becomes a
gas; this effect, called auto refrigeration,
causes the fluid to cool rapidly. The waxy
materials will turn from liquid to solid and
can be filtered out or skimmed from the top
of the tank.
HYDROFINISHING UNIT
• In this final processing stage, the lube
base oils are stabilized and their colour is
further improved by hydrogenation under
severe operating conditions in the
presence of a catalyst.
• The hydrofinished lube oils are dispatched
to refinery storage tanks for distribution to
Oil Marketing/Lube Oil Blending
Companies.
•Environmental
Pollution in
Petroleum
Refineries
Air Pollutants from Refining
Operations
Major air pollutant that may be emitted
from refining operations are
• Sulphur Compounds
• Hydrocarbons
• Nitrogen oxides
• Particulates
• etc
Sulphur Compounds
• The main source of sulphur dioxide
emissions are from combustion
operations such as fired heaters ,
boilers & catalytic cracking.
Hydrocarbons
• The emissions of hydrocarbons result
mainly from evaporation of light oils
during storage & handling of crude &
petroleum products & from leaks.
Nitrogen oxides
• Combustion of fuel in fired heaters &
boilers & in internal combustion
engines , electric generators are the
main source of Nitrogen oxides
emissions.
Particulates
• The major sources include sludge
burner, emergency flares , and
boilers , furnaces , emergency
operations and incomplete
combustion.
Water Pollution from
Refining Operations
• Water is used in petroleum refineries
for variety of puposes.Since water
does not enter into the final product ,
it can be expected that 80-90% of the
water supplied to the refinery comes
out as waste water.
Characteristics Of wastewater from
Petroleum Refineries in Pakistan
S.No.
Effluent characteristics
Value
1
Flow,1/kg oil
1.5
2
pH
6.8-7.2
3
Suspended solids, mg/l
200-400
4
BOD , mg/l
100-300
5
COD , mg/l
---
6
BOD/COD
---
7
BOD load, g/unit product
0.3