Oil refinery

An oil refinery is a big factory where crude oil, also called petroleum, is changed into many useful products like gasoline, diesel fuel, asphalt base, and heating oil. These products help power cars, heat homes, and build roads. Inside the refinery, crude oil goes through special processes to separate it into different parts, much like how water can be turned into ice, steam, or liquid.

Oil refineries are huge and complex, filled with long pipes and big machines. They work like giant chemical factories, using many different technologies to turn crude oil into valuable products. The biggest oil refinery in the world is the Jamnagar Refinery in Gujarat, India, which can process over one million barrels of oil each day.

These refineries are very important because they help make the fuels and materials we use every day. They are part of the petroleum industry’s downstream sector, meaning they take the raw oil and turn it into things people need. Refineries are often found near places where oil is stored, so they can easily get their supply of crude oil.

History

The Chinese were among the first to refine oil. As early as the first century, they refined crude oil for energy. In the late Northern Wei dynasty, a Chinese writer described how to make different oils from crude oil.

Persian chemists also refined oil, and streets in Baghdad were paved with tar from petroleum. In the 9th century, oil fields were used near modern Baku, Azerbaijan. Arab and Persian chemists made flammable products from oil for military use.

In the Northern Song dynasty, China had a workshop that made refined oil for weapons. Troops used this oil in iron cans to start fires on enemy soldiers.

Before the 1800s, people in many places used petroleum, but the modern oil industry began in 1846 when a man in Canada found a way to make kerosene from coal. Soon after, in 1854, another man in Poland began making kerosene from oil wells.

The first oil well in North America was drilled in Canada in 1858. In the United States, oil drilling began in 1859 in Pennsylvania. At first, refineries mainly made kerosene for oil lamps. But with the invention of the automobile, there was a big need for gasoline, which led to faster growth in the oil industry.

America’s first oil refinery was built in Pittsburgh in 1853. Another early refinery was built in Jasło, Poland, in 1854. The first large refinery opened in Ploiești, Romania, in 1856–1857.

In the early 1940s, most refineries in the United States only distilled crude oil. During World War II and after, new methods were developed to meet the growing need for gasoline and aircraft fuel.

United States

Main article: Petroleum refining in the United States

In the 1800s, U.S. refineries mainly made kerosene from crude oil. Gasoline was considered waste and was often dumped. The automobile changed this, and gasoline and diesel became the main products.

Today, refineries must meet strict rules to keep air and water clean. Because it became so hard and expensive to get permits to build new refineries, no new ones were built in the U.S. from 1976 until 2014. Many old refineries closed, but the ones that remained got bigger and more efficient. In 1982, the U.S. had 301 refineries, but by 2010, there were only 149. However, the total ability to process oil stayed about the same, and by 2014, the total capacity even went up a little.

In 2009 and 2010, many refineries closed or were sold because there was less demand for oil products and there was already a lot of oil available before the economic recession.

Operation

The oil refinery in Haifa, Israel can process about 9 million tons (66 million barrels) of crude oil each year. Crude oil needs to be processed because it isn’t useful in its raw form for most things.

In a refinery, the different parts of crude oil are separated into useful products like fuels, lubricants, and materials used to make things such as plastics, detergents, and fibers. This is done by heating the oil and separating it based on how easily it evaporates. Refineries turn heavy oils into lighter, more useful fuels and can also make special chemicals needed for many products we use every day.

Major products

Petroleum products come from crude oil when it is processed in oil refineries. Most of the oil is turned into fuels like gasoline, jet fuel, diesel, heating oil, and other heavier fuels.

Oil refineries also make other important materials. These include hydrogen, light hydrocarbons, and special mixtures used in chemical plants. Some of these materials are used to make plastics and other useful products. The oil also has sulfur, which is turned into elemental sulfur for sale to the chemical industry. The heat from this process is often used in other parts of the refinery.

Petroleum products are materials derived from crude oil (petroleum) as it is processed in oil refineries. The majority of petroleum is converted to petroleum products, which includes several classes of fuels.

Oil refineries also produce various intermediate products such as hydrogen, light hydrocarbons, reformate and pyrolysis gasoline. These are not usually transported but instead are blended or processed further on-site. Chemical plants are thus often adjacent to oil refineries or a number of further chemical processes are integrated into it. For example, light hydrocarbons are steam-cracked in an ethylene plant, and the produced ethylene is polymerized to produce polyethene.

To ensure both proper separation and environmental protection, a very low sulfur content is necessary in all but the heaviest products. The crude sulfur contaminant is transformed to hydrogen sulfide via catalytic hydrodesulfurization and removed from the product stream via amine gas treating. Using the Claus process, hydrogen sulfide is afterward transformed to elementary sulfur to be sold to the chemical industry. The rather large heat energy freed by this process is directly used in the other parts of the refinery. Often an electrical power plant is combined into the whole refinery process to take up the excess heat.

According to the composition of the crude oil and depending on the demands of the market, refineries can produce different shares of petroleum products. The largest share of oil products is used as "energy carriers", i.e. various grades of fuel oil and gasoline. These fuels include or can be blended to give gasoline, jet fuel, diesel fuel, heating oil, and heavier fuel oils. Heavier (less volatile) fractions can also be used to produce asphalt, tar, paraffin wax, lubricating and other heavy oils. Refineries also produce other chemicals, some of which are used in chemical processes to produce plastics and other useful materials. Since petroleum often contains a few percent sulfur-containing molecules, elemental sulfur is also often produced as a petroleum product. Carbon, in the form of petroleum coke, and hydrogen may also be produced as petroleum products. The hydrogen produced is often used as an intermediate product for other oil refinery processes such as hydrocracking and hydrodesulfurization.

Categories of petroleum products

light distillates

middle distillates

heavy distillates and residuum

These require blending various feedstocks, mixing appropriate additives, providing short-term storage, and preparation for bulk loading to trucks, barges, product ships, and railcars. This classification is based on the way crude oil is distilled and separated into fractions.

Other products

Sulfur (or sulfuric acid), byproducts of sulfur removal from petroleum which may have up to a couple of percent sulfur as organic sulfur-containing compounds. Sulfur and sulfuric acid are useful industrial materials. Sulfuric acid is usually prepared and shipped as the acid precursor oleum.

Over 6,000 items are made from petroleum waste by-products, including fertilizer, floor coverings, perfume, insecticide, petroleum jelly, soap, and vitamin capsules.

Sample of [crude oil](/wiki/Crude_oil) (petroleum)

[Cylinders](/wiki/Gas_cylinder) of [liquified petroleum gas](/wiki/Liquified_petroleum_gas)

Sample of gasoline

Sample of [kerosene](/wiki/Kerosene)

Sample of [diesel fuel](/wiki/Diesel_fuel)

[Motor oil](/wiki/Motor_oil)

Pile of asphalt-covered aggregate for formation into [asphalt concrete](/wiki/Asphalt_concrete)

[Sulphur](/wiki/Sulphur)

Chemical processes

Desalter

A desalter is a special part of an oil refinery that takes salt out of crude oil. The salt is mixed with water in the oil, not in the oil itself. This is usually the first step in making new products from crude oil.

Atmospheric and vacuum distillation

Atmospheric and vacuum distillation are important ways to separate different parts of crude oil. These processes make products like gasoline and diesel fuel. Distillation happens first at normal air pressure and then using a vacuum. This helps separate the oil into lighter and heavier parts.

Hydrodesulfurization

Hydrodesulfurization is a process that takes sulfur out of fuels like gasoline and diesel. This is done to stop bad air pollution when these fuels are burned in cars, planes, and other machines.

Catalytic reforming

Catalytic reforming changes some parts of crude oil into better gasoline. It turns simple molecules into more useful ones and makes extra hydrogen gas that helps in other refinery steps.

Fluid catalytic cracking

Fluid catalytic cracking breaks down bigger oil molecules into smaller ones to make more gasoline and useful gases. This method is better than older ways of breaking down oil.

Hydrocracker

Hydrocracking is a special way to break down big oil molecules using added hydrogen gas. It makes valuable products from heavy oil fractions.

Merox

Merox is a process that takes unwanted substances out of fuels like jet fuel and propane. It changes these substances into safer liquid forms.

Coker unit

A coker unit changes leftover heavy oil into smaller molecules and leaves behind a solid called petroleum coke. This helps make more useful products from the heavy parts of oil.

Alkylation unit

An alkylation unit mixes two small oil molecules together to make a bigger one that is great for gasoline. This makes the gasoline stronger and better.

Dimerization unit

Dimerization turns small oil molecules into bigger ones that can be used to make high-quality gasoline. These bigger molecules help improve gasoline.

Isomerization

Isomerization changes straight oil molecules into bent ones, which are better for gasoline. This also helps make other useful products.

Steam reforming

Steam reforming is a way to make hydrogen gas from natural gas and water. This hydrogen is used for many important things, like making ammonia or methanol.

LNG storage tank

LNG storage tanks are special containers for storing liquefied natural gas at very cold temperatures. These tanks keep the gas safe at -162 °C and are used on the ground, above ground, or on ships.

Amine gas treater

Amine gas treating is a process that cleans gases by taking out bad-smelling and harmful parts like hydrogen sulfide and carbon dioxide. This helps make the gases safer to use.

Power generation

Cooling towers move water to keep things cool, boiler plants make steam for special machines, and instrument air systems help control equipment.

Waste treatment

Wastewater systems clean water from the refinery so it can be reused or safely disposed of. Special tools help remove unwanted substances from oil products before they are stored.

Flow diagram of typical refinery

The image below shows a simple picture of how an oil refinery works. It illustrates the different steps and how the materials move from the raw oil to the finished products. This picture shows just one way an oil refinery can be set up — there are actually hundreds of different setups possible. The picture also does not include the extra buildings and tools that refineries need, like those that provide steam, cooling water, or electricity, nor does it show the storage tanks for the raw oil and the products made along the way.

Different refineries can have different setups. For example, a vacuum distillation unit can also make products like special oils used in factories or for making clothes, as well as oils for machines and cars, and different kinds of wax.

Crude oil distillation unit

The crude oil distillation unit (CDU) is the first place where oil is processed in a refinery. It sorts the oil into different parts based on how hot they boil. This helps make many useful products.

The oil is first heated and cleaned before going into the distillation unit. It is then heated even more and put into the bottom of a tall tower. As it moves up, different parts cool down and are collected at different levels. These parts are stored before being made into things like gasoline and other fuels.

Location of refineries

When choosing a place to build an oil refinery, there are important things to think about. The place should be far enough from homes to keep people safe. It also needs good roads and ways to bring in raw materials and send out finished products.

Oil refineries often sit near rivers or the coast because they need a lot of water and easy access for ships. Pipelines are great for moving large amounts of oil, but smaller products might travel by train, truck, or boat. Places that make special chemicals also need extra space for mixing and processing.

Safety and environment

Oil refineries can release different chemicals into the air and often have a strong smell. They also create wastewater and can sometimes have accidents like fires or explosions. The noise from refineries can affect people’s health too.

Many countries have rules to limit the harmful things refineries can release. Most refineries have special equipment to follow these rules. In the United States, no big new refineries have been built since 1976, but many existing ones have gotten bigger. Some older refineries have closed down. Because of safety and health concerns, refineries are often placed far from big cities. However, some refineries are close to towns and can sometimes cause problems for people living nearby.

Worker health

Modern oil refineries use many chemical reactions that need exact temperatures and pressures. This makes the work complex, but systems are designed to keep workers safe. Even so, some jobs can still be risky.

Workers might face dangers from chemicals or machines. Some chemicals can be harmful if inhaled or touched. Machines can cause injuries, and loud noises can affect hearing. Workers must follow safety rules and use protective gear like ear covers and safe clothing to stay healthy.

In the United States, groups like the Occupational Safety and Health Administration watch over refinery safety. Rules help keep workers safe from fires, chemical spills, and other dangers.

Corrosion

Corrosion is a big problem in oil refineries because it can make machines break and need fixing often. In the United States, it cost the oil industry a lot of money many years ago.

Corrosion can happen in different ways, like from water or certain chemicals. Most machines are made from a type of steel that is cheap and strong, but sometimes more special metals are needed for very tough places. Refineries fight corrosion by watching for it, fixing things before they break, and using the right materials. They also use special coatings to protect the machines. Newer ways to watch corrosion in real time help engineers make quick changes to keep things running smoothly.