Oil Refinery
After crude oil is removed from the ground, it is sent to a refinery by pipeline or ship.
At a refinery, different parts of the crude oil are separated into useable petroleum products.
A refiner's choice of crude oil will be influenced by the type of processing units at the refinery. Refineries fall into three broad categories.
The simplest refinery is a topping plant
Which consists only of a distillation unit and probably a catalytic reformer to provide octane.
Yields from this plant would most closely reflect the natural yields from the crude processed.
Typically only condensates or light sweet crude would be processed at this type of facility,
unless markets for heavy fuel oil (HFO) are readily and economically available.
Asphalt plants are topping refineries that run heavy crude oil because they are only interested in producing asphalt.
The first step is to separate the crude oil into its naturally occurring components. This is known as separation.
A furnace heats and partly vaporises the "feed stream".
The vapour and liquid mixture is then fed into the bottom section of the tower.
As the vapour rises, it cools down and the different components condensate.
Heavier oils, with longer hydrocarbon chains, will condensate first and the gasses (with very short hydrocarbon chains) are collected from the top.
The “yield” from a distillation tower refers to the relative percentage of each of the separated components, known as product streams.
This will vary according to the characteristics of the crude oil being processed.
Products from the distillation tower range from gases at the top to very heavy, viscous liquids at the bottom.
In all cases, these product streams are still considered “unfinished” and require further processing to become useful products.
The products from distillation, are frequently not in the same proportions as the product mix that consumers demand.
The biggest difference is that there is too little petrol, jet fuel (Kerosene) and Diesel, and too much heavy oil naturally occurring in crude oil.
That is why conversion processes are so important.
Their primary purpose is to convert low valued heavy oil into high valued petrol.
The next level of refining is called a cracking refinery.
This refinery takes the gas oil portion from the crude distillation unit (a stream heavier than diesel fuel, but lighter than HFO) and breaks it down further into gasoline and distillate components using catalysts, high temperature and/or pressure.
Converting heavier hydrocarbons to lighter hydrocarbons can be compared to cutting a link on a steel chain to make two smaller chains.
This is the function of the Fluidised Catalytic Cracking unit (FCCU).
The FCCU catalyst promotes the reaction that breaks the heavier chains in the right place to make as much petrol as possible.
However, even with the catalyst, the reactions require a lot of heat; therefore the FCCU reactor operates at about 530 degrees Celsius.
Because you cannot control exactly where you cut the chain, in the middle or at the end, the process will produce some short chain hydrocarbons.
Therefore, in addition to breaking chains, there are times when you want to put chains together or change the form of the chain.
This is where the Catalytic Reformer and Alkylation are necessary.
Specialised catalysts are of critical importance in most of these processes.
The last level of refining is the coking refinery.
This refinery processes residual fuel, the heaviest material from the crude unit and thermally cracks it into lighter product in a coker or a hydrocraker.
The addition of a fluid catalytic cracking unit (FCCU) or a hydro cracker significantly increases the yield of higher-valued products like gasoline and diesel oil from a barrel of crude,
allowing a refinery to process cheaper, heavier crude while producing an equivalent or greater volume of high-valued products.
Figure 2. Basic Petroleum Refining Process. Source: Energy Information Administration
Hydrotreating is a process used to remove sulphur from finished products.
As the requirement to produce ultra low sulphur products increases, additional hydrotreating capability is being added to refineries.
Refineries that currently have large hydrotreating capability have the ability to process crude oil with a higher sulphur content.
Figure 4 demonstrates that using the same crude input (in this example a heavy crude with a 27 API) yields a very different range of petroleum products depending on the refining units and processes used.
In the case of the cracking refinery, the addition of other blending materials at various stages of production is required but the resulting volumetric output is greater than the volume of the crude oil input.
Each refinery is unique due to age / technology and modifications over time, but generalizations are possible.
The installation of additional conversion capability increases the yield of clean products and reduces the yield of heavy fuel oil.
However, increased conversion capability would generally result in higher energy use and, therefore, higher operating costs.
These higher operating and capital costs must be weighed against the lower cost of the heavier crude oil.
Canada has primarily cracking refineries.
These refineries run a mix of light and heavy crude oils to meet the product slate required by Canadian consumers.
Historically, the abundance of domestically produced light sweet crude oils and a higher demand for distillate products,
such as heating oil, than in some jurisdictions reduced the need for upgrading capacity in Canada.
However, in more recent years, the supply of light sweet crude has declined and newer sources of crude oil tend to be heavier.
Many of the Canadian refineries are now being equipped with upgraders to handle the heavier grades of crude oil currently being produced.
Australia:
In Australia there are 7 operating refineries.- BP owns and operates two refineries.
- BP’s Kwinana Refinery is one of the most modern in the southern hemisphere.
It is Western Australia’s only refinery and with a capacity of 138,000 barrels of crude oil per day, it is Australia’s largest. - BP’s Bulwer Island Refinery in Queensland has a capacity of 88,000 barrels of oil a day.
Products include Petrol, Bitumen, Aviation Fuel, Fuel oils, LPG (including propane and butane), Diesel fuels (gas oils).
- BP’s Kwinana Refinery is one of the most modern in the southern hemisphere.
- Caltex owns and operates 2 petroleum fuels refineries (Lytton QLD) and Kurnell NSW) with a combined capacity of more than 35 million litres per day,
making Caltex the largest refiner of crude oil in Australia.
They also have a lubricating oil refinery, adjacent to the Kurnell fuels refinery.
- The Lytton refinery is located at the mouth of the Brisbane River to the south of the Brisbane CBD.
The refinery was commissioned in 1965 and with a crude oil throughput of 17 million litres per day, is the largest oil refinery in Queensland and fifth largest oil refinery in Australia.
On average, production at the Lytton refinery is comprised of 45% petrol, 35% diesel, 13% jet fuel, 2% fuel oil and 5% LPG and other gases. - The two Kurnell refineries are located on the southern shore of Botany Bay in Sydney 's south-east.
A petroleum fuels refinery, commissioned in 1956.
Based on a crude oil throughput capacity of 20 million litres per day, this is the largest refinery in NSW and the second largest of the seven operating oil refineries in Australia.
Approximately 50% of production at the Kurnell fuels refinery is petrol; 22% is diesel; 15% jet fuel; 5% fuel oil; 4% LPG, butane and propane; 1% bitumen; and the remainder is made up of lubricating oil base stocks, waxes, process oils and sulphur.
Located adjacent to the Kurnell fuels refinery is a 600,000 litre per day lubricating oil refinery.
- The Lytton refinery is located at the mouth of the Brisbane River to the south of the Brisbane CBD.
- Shell operates 2 refineries.
- The Clyde Refinery in NSW.
Each year the refinery processes about 30 million barrels of crude oil and other feeds.
It produces over 4.8 billion litres of petroleum products - equal to around 13 million litres per day.
Major products produced are: Petrol(of which 20% are high octane grades) Diesel Fuel, Jet Fuel, Bitumen and LPG. - The Geelong Refinery in Victoria.
The refinery processes about 38 million barrels of crude oil and other feedstocks.
It produces about six billion litres of petroleum products - around 17 million litres a day.
- The Clyde Refinery in NSW.
- Exxon Mobil operates the Altona Refinery in Victoria.
The refinery produces up to 13 million litres of refined products per day.
Petrol 50 %, diesel 25 % and jet fuel around 15 %. They also produce bitumen and LPG (Liquefied Petroleum Gas).
Exxon Mobil also owns the Adelaide refinery.
Production at the Adelaide refinery ceased in July 2003, although the refinery is being maintained in a condition that will allow a restart should viable operations be sustainable in the future.
FAQ
How much petrol can you get out of a litre of crude oil?
How much petrol or diesel you get out of one barrel of crude is hard to say.
This amount depends on the type of oil used i.e. heavy or light, and what the refinery operator needs.
Yields from the simplest refinery, a topping plant, would most closely reflect the natural yields from the crude processed.
A light crude would yield a higher percentage of Distillate and Gasoline than a very heavy crude.
The yield of higher-valued products like gasoline and diesel oil from a barrel of crude using a cracking refinery would be greater, and that of a coking refinery would be greater still.
The operator of the last two types of refineries can adjust the percentages, depending on requirement. In winter more heating oil is needed, in summer more fuel for transport.
In theory it would be possible to process almost any type of crude oil into (almost) 100% petrol or diesel.
In practice, the refinery operator has to balance the cost of doing this against the profit he would make.
Figure 4.
Comparison of Yields by Refinery Type
"Heavy Crude Oil Example"
For More Frequently Asked Questions see FAQ section in Petrol Price Calculation