START WITH CRUDE OIL
Try living a day without utilizing something made from crude oil. It is a difficult prospect in the current economy. Crude oil is the term for unprocessed oil. That is the material that comes out of the ground. Crude oil is a fossil fuel, meaning that it was made naturally from decaying plants and animals living in ancient seas millions of years ago -- most places you can find crude oil were once sea beds. Crude oils vary in color, from clear to tar-black, and in viscosity, from water to almost solid.
Crude oils are such a useful starting point for so many different substances because they contain hydrocarbons. Hydrocarbons are molecules that contain hydrogen and carbon and come in various lengths and structures, from straight chains to branching chains to rings.
There are two things that make hydrocarbons exciting to chemists: Hydrocarbons contain a lot of energy. Many of the things derived from crude oil like gasoline, diesel fuel, paraffin wax and so on take advantage of this energy.
Hydrocarbons can take on many different forms. The smallest hydrocarbon is methane (CH4), which is a gas that is a lighter than air. Longer chains with 5 or more carbons are liquids. Very long chains are solids like wax or tar. By chemically cross-linking hydrocarbon chains you can get everything from synthetic rubber to nylon to the plastic in tupperware. Hydrocarbon chains are extremely versatile.
The problem with crude oil is that it contains hundreds of different types of hydrocarbons all mixed together. They have to be separated to be made into useful products. Fortunately there is an easy way to separate things, and this is what oil refining is all about.
Different hydrocarbon chain lengths all have progressively higher boiling points, so they can all be separated by distillation (heating). This is what happens in a traditional oil refinery - in one part of the process, crude oil is heated and the different chains are pulled out by their vaporization temperatures. Each different chain length has a different property that makes it useful in a different way.
To understand the diversity contained in crude oil, and to understand why refining crude oil is so important in our society, look through the following list of products that come from crude oil:
Petroleum gas - used for heating, cooking, making plastics
commonly known by the names methane, ethane, propane, butane
boiling range = less than 104° F (40° C).
often liquified under pressure to create LPG (liquified petroleum gas)
Naphtha or Ligroin - intermediate that will be further processed to make gasoline
boiling range = 140 to 212° F (60 to 100° C).
Gasoline - motor fuel
boiling range = 104 to 401° F (40 to 205° C).
Kerosene - fuel for jet engines and tractors; starting material for making other products
boiling range = 350 to 617° F (175 to 325° C).
Gas oil or Diesel distillate - used for diesel fuel and heating oil;
boiling range = 482 to 662° F (250 to 350° C).
Lubricating oil - used for motor oil, grease, other lubricants
boiling range = 572 to 700° F (300 to 370° C).
Heavy gas or Fuel oil - used for industrial fuel
boiling range = 700 to 1112° F (370 to 600° C).
Residual Solids - coke, asphalt, tar, waxes
boiling range = greater than 1112° F (600° C).
CRUDE OIL REFINED
The oil refining process starts with a fractional distillation column.The problem with crude oil is that it contains hundreds of different types of hydrocarbons all mixed together. They have to be separated to be made into useful products. Fortunately there is an easy way to separate things, and this is what oil refining is all about.
Different hydrocarbon chain lengths all have progressively higher boiling points, so they can all be separated by distillation (heating). This is what happens in a traditional oil refinery - in one part of the process, crude oil is heated and the different chains are pulled out by their vaporization temperatures. Each different chain length has a different property that makes it useful in a different way.
To understand the diversity contained in crude oil, and to understand why refining crude oil is so important in our society, look through the following list of products that come from crude oil:
Petroleum gas - used for heating, cooking, making plastics
commonly known by the names methane, ethane, propane, butane
boiling range = less than 104° F (40° C).
often liquified under pressure to create LPG (liquified petroleum gas)
Naphtha or Ligroin - intermediate that will be further processed to make gasoline
boiling range = 140 to 212° F (60 to 100° C).
Gasoline - motor fuel
boiling range = 104 to 401° F (40 to 205° C).
Kerosene - fuel for jet engines and tractors; starting material for making other products
boiling range = 350 to 617° F (175 to 325° C).
Gas oil or Diesel distillate - used for diesel fuel and heating oil;
boiling range = 482 to 662° F (250 to 350° C).
Lubricating oil - used for motor oil, grease, other lubricants
boiling range = 572 to 700° F (300 to 370° C).
Heavy gas or Fuel oil - used for industrial fuel
boiling range = 700 to 1112° F (370 to 600° C).
Residual Solids - coke, asphalt, tar, waxes
boiling range = greater than 1112° F (600° C).
CHEMICAL PROCESSING
Newer refineries use Chemical processing on some of the fractions to make others, in a process called conversion. Chemical processing, for example, can break longer chains into shorter ones. This allows a refinery to turn diesel fuel into gasoline depending on the demand for gasoline. Refineries must treat the fractions to remove impurities. Refineries combine the various fractions (processed, unprocessed) into mixtures to make desired products. For example, different mixtures of chains can create gasolines with different octane ratings.One fraction can be changed into another by one of three methods:
(1) breaking large hydrocarbons into smaller pieces (cracking)
(2) combining smaller pieces to make larger ones (unification)
(3) rearranging various pieces to make desired hydrocarbons (alteration)
Cracking
Cracking takes large hydrocarbons and breaks them into smaller ones.
There are several types of cracking: Thermal - heating large hydrocarbons at high temperatures (sometimes high pressures as well) causes them to break apart. Steam - high temperature steam (1500° F (816° C) is used to break ethane, butane and naptha into ethylene and benzene, which are used to manufacture chemicals. Visbreaking - residual from the distillation tower is heated (900° F (482° C), cooled with gas oil and rapidly burned (flashed) in a distillation tower. This process reduces the viscosity of heavy weight oils and produces tar. Coking - residual from the distillation tower is heated to temperatures above 900° F (482° C) until it cracks into heavy oil, gasoline and naphtha. When the process is done, a heavy, almost pure carbon residue is left (coke); the coke is cleaned from the cokers and sold.
Catalysts used in catalytic cracking or reforming
Catalytic - uses a catalyst to speed up the cracking reaction. Catalysts include zeolite, aluminum hydrosilicate, bauxite and silica-alumina. fluid catalytic cracking - a hot, fluid catalyst 1000° F 538° C) cracks heavy gas oil into diesel oils and gasoline. Hydrocracking - similar to fluid catalytic cracking, but uses a different catalyst, lower temperatures, higher pressure, and hydrogen gas. It takes heavy oil and cracks it into gasoline and kerosene (jet fuel).After various hydrocarbons are cracked into smaller hydrocarbons, the products go through another fractional distillation column to separate them.
Unification
Sometimes, you need to combine smaller hydrocarbons to make larger ones -- this process is called unification. The major unification process is called catalytic reforming and uses a catalyst (platinum, platinum-rhenium mix) to combine low weight naphtha into aromatics, which are used in making chemicals and in blending gasoline. A significant by-product of this reaction is hydrogen gas, which is then either used for hydrocracking or sold.
Alteration
Sometimes, the structures of molecules in one fraction are rearranged to produce another. Commonly, this is done using a process called alkylation. In alkylation, low molecular weight compounds, such as propylene and butylene, are mixed in the presence of a catalyst such as hydrofluoric acid or sulfuric acid (a by-product from removing impurities from many oil products). The products of alkylation are high octane hydrocarbons, which are used in gasoline blends to reduce knocking. |
| Oil Refining combines all of these processes. |
Treating and Blending the Fractions
Distillated and chemically processed fractions are treated to remove impurities, such as organic compounds containing sulfur, nitrogen, oxygen, water, dissolved metals and inorganic salts. Treating is usually done by passing the fractions through the following:
(1) a column of sulfuric acid - removes unsaturated hydrocarbons (those with carbon-carbon double-bonds), nitrogen compounds, oxygen compounds and residual solids (tars, asphalt)
(2) an absorption column filled with drying agents to remove water
sulfur treatment and hydrogen-sulfide scrubbers to remove sulfur and sulfur compounds
After the fractions have been treated, they are cooled and then blended together to make various products, such as:
(2) an absorption column filled with drying agents to remove water
sulfur treatment and hydrogen-sulfide scrubbers to remove sulfur and sulfur compounds
After the fractions have been treated, they are cooled and then blended together to make various products, such as:
gasoline of various grades, with or without additives
lubricating oils of various weights and grades (e.g. 10W-40, 5W-30)
kerosene of various various grades
jet fuel
diesel fuel
heating oil
chemicals of various grades for making plastics and other polymers
 |
| Plastics produced from refined oil fractions |
Designer Corn Seed Stolen by Chinese
The case of the missing corn seeds first broke in May 2011 when a manager at a DuPont research farm in Iowa noticed an Asian man on his knees, digging up a field.
US Oil Production Projected to Surge, Leading to Lower Prices at Gas Pumps
Domestic oil production will continue to soar for years to come, the Energy Department predicted in early 2014, scaling to levels not seen in nearly half a century by 2016.
Does the President of the United States Control Gas Prices?
Any respectable economist will tell you that the president of the United States does not control gas prices.