Date post: | 18-Oct-2014 |
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Education |
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Petroleum Refinery
Basics
• Crude Oil components
• Refinery Flowchart
• Other refinery units
• Unit Opns & Unit Proces in refining
• Physical and process Hazards
Thanks to
• John Kulluk Ph.D.
• Torrance Fire Department
• &
• Robert Distaso PE – 714/573-6253
• Orange County Fire Authority
Petroleum is extracted from underground reserves;
then it is cracked or “refined” into end products for
various uses. The petroleum industry thus has two
parts: an oil exploration and production industry
upstream and a refinery industry downstream.
Most oil producers also own refineries. But the
reverse is not true; a high proportion of oil is sold
to refinery companies that do not produce crude
oil.
Refining Means. . .
1. To reduce to a pure state, to remove
impurities
2. To improve or perfect
Salable products are made from crude.
What is Crude Oil?
• Mixture of organic
carbon chain
molecules
• Impurities include
sulfur and nitrogen
compounds
• Some metals and
salts too
Components such as . . .
• Straight-Chain
Hydrocarbons
• Olefins
• Cyclic H/C
• Aromatics
(Benzene, toluene,
xylenes)
• Mercaptans
• Hydrogen Sulfide
(H2S)
• Greases
• Propane
• LPG
Other Hazardous Materials
• Sulfur
• Hydrofluoric Acid (HF)
• Sulfuric Acid (H2SO4)
• Ammonia (NH3)
• Sodium Hypochlorite
• Radioactive Materials
• Chlorine
• Amines
• MEK
• Sulfur Dioxide (SO2)
• Heavy Metal Catalysts
• Sour Water
• Caustic (fresh/spent)
• Alcohol
• Asbestos
Heat & Mass Transfer Opns
The reactor effluent is then cooled via heat
exchange with unit feedstocks, fractionated into
the desired product streams via distillation,
which are then further cooled via heat exchange
with unit feedstocks. Individual refinery
processes are described subsequently,
simplified process flow diagrams will be
provided to illustrate the specific process flow
sequence for the applicable process.
Heat & Mass Transfer Opns
In fractionation or distillation the feedstock is
distilled into various cuts of target boiling ranges or
even separated into individual hydrocarbon
compounds. Distillation is accomplished by
imposing a temperature profile across the tower
enabling differences in the equilibrium
compositions of the vapor and liquid phases to
change the compositions throughout the distillation
tower.
Heat is added to the hydrocarbons at the bottom
of the tower through heat exchange in a reboiler
which vaporizes a portion of the tower bottoms
liquid for recirculation to the bottom of the tower.
Heat is removed from the top of the tower through
heat exchange in an overhead condenser and
then returning a portion of the condensed
hydrocarbons back to the tower as .reflux..
This heat addition at the bottom and heat
removal from the top of the tower establishes the
temperature profile across the tower. In some
applications, additional heat is removed by heat
exchange with circulating liquid „pump-around‟
streams which are withdrawn and returned at
intermediate levels of the tower. Perforated tray
decks or packed bed sections allow intimate
contacting of the liquid and vapor phases
followed by separation.
• Petroleum crude oils are : numerous hydrocarbons.
• Hydrocarbons are chemical compounds made up of
predominantly carbon and hydrogen.
• Hydrocarbons found in crude oils generally also
contain the elements sulfur and nitrogen. Many crude
oils also contain absorbed levels of the toxic gas
hydrogen sulfide (H2S).
Composition of crude oil
• Crude oils may contain trace amounts of metals
such as nickel and vanadium, as well as salts.
• Most of the nonhydrogen, non-carbon elements
found in crude oils are undesirable and are
removed from the hydrocarbons in total or in part
during refinery processing.
Components_ To be removed
Refinery Process Flow Chart
Dis
tilling
Flasher
Visbreaker
CCU
Alky
Sp
litter
Hydrotreating
Hydrotreating
Isom
Reformer
Gas Plant
Sulfur
Fuel Gas
Gasoline
Jet Fuel
Distillate Fuel
Residual
Fuel Leffler, 1985
The principal products, with their
approximate boiling points, are petroleum
gas (20ºC), naphtha (40ºC), petrol (70ºC),
kerosene and jet fuel (120ºC), diesel (200ºC),
lubricant (300ºC), and furnace oil (370ºC);
solid petroleum coke collects at the bottom
after the liquid fractions are removed.
FLUID CATALYTIC CRACKING
HYDRO TREATING
Many fuels products are treated as a finishing
step prior to being shipped as .finished. products.
Treating removes impurities which cause
objectionable odors, unwanted colors or
corrosion of the product. Hydrogen sulfide (H2S)
and other sulfur compounds such as mercaptans
are examples of such impurities.
Amine contacting using aqueous amine solutions such as
monoethanolamine (MEA), diethanolamine (DEA), or
methyldiethanol amine (MDEA) are commonly used to
remove H2S from light ends streams prior to
disposition as fuel gas or propane (i.e., Liquefied
Petroleum Gas or .LPG.) product. The amine solution is
then regenerated in a still in which the application
of heat drives off the H2S. The H2S-rich stream produced
from the still (called acid gas.) is then routed to the Sulfur
Conversion process.
Other Refinery Units • Steam Generation
• Wastewater Treatment
• Hydrogen Generation
• Power Generation (e.g., cogen)
• Air Separation Plant
• Loading/Unloading - Railcar, Trucks, etc.
• Storage (high pressure hydrocarbon, crude oil, intermediates)
Floating-Roof Tanks - 150„ diameter is common
Spherical Tanks - 50„ are common
Horton Spheroid (refrigerated)
Steam-Heated Tanks for “Heavier” Products
• Self-Contained Firewater Supply
• Firewater Pumps
What’s All this Stuff?
What Goes on at a Refinery. . .?
• Separation of components by distillation, e.g.:
Atmospheric
Vacuum
Hydrotreating (uses excess hydrogen)
• Breaking apart molecules to make smaller ones, e.g.:
catalytic cracking
hydrocracking
• Joining molecules to make bigger ones, e.g.:
Reforming - alkylation that lengthens the hydrocarbon chain
Reforming - cyclic that generates hydrogen
Physical Hazards
• High Pressure/Temperature Steam
• Oil/Gas-Fired Furnaces
• Acoustic
• High Voltage (4160V, 480V, 13.2 kV)
• Falling Hazards
• Confined Space Hazards
• Cranes/Lifting Hazards
• Hot Work Hazards
• Acid Exposure
• Toxic Vapors
• Radiation
• Flammability Hazards
Common PPE Requirements
• Hardhat
• Hardsoled / Hardtoe Shoes
• Safety Glasses with Side
Protection
• Safety Goggles or Faceshield
• Fire-Resistant Clothing
Process Hazards
• Emergency Flare
• Atmospheric Pressure Relief
• High Temperature (up to 2000oF)
• Low Temperature (e.g., Brittle Fracture)
• High Pressure (up to 3000 psig)
• Low Pressure (e.g., vacuum)
Some petrochemicals are produced in large enough bulk to
take a significant proportion of refinery products: the
world consumed 345 million tons of hydrocarbons in 2004
to make 310 million tons of petrochemicals.
Most of the hydrocarbons are first turned into one of three
intermediates - ethylene, propylene and aromatics – before
being converted to other products. Of the latter, plastics
accounted for 225 million tons, and fibres for 38 million
tons; solvents, detergents and synthetic rubber accounted
for most of the rest.