How car oil is refined

How car oil is refined

Here you can get car oil is refined. Here we provide Refining, fractions, Cracking, properties of Petrol and Storage/transport.

The fuel used in a modern car, whether petrol, diesel or maybe LPG ( Liquid Petroleum Gas ), has got to meet high standards of purity if the car’s engine is to run smoothly. Modern fuels need to be sufficiently volatile to ignite quickly, even under adverse conditions, and that they need to have the right blend of hydrocarbons to burn evenly enough to develop useful power in an indoor combustion engine. The fuel must even have the proper octane value to stop pinking (detonating too early) which may cause engine damage.

Internal combustion engines are tailored to run on a specific grade of fuel and tuned to run quite on the brink of the bounds which that fuel can support, so consistent quality is vital in modern fuels. Both petrol and diesel are derived from crude oil, which may be a complex mixture of the many many different hydrocarbons also as other products which require to be removed during refining. Crude oils vary from source to source; they typically contain light volatile liquids, petrol among others, also the maximum amount heavier, almost solid constituents, like bitumen. Separating out and purifying petrol and diesel from crude oil requires complex processes, which are carried out in an oil refinery.


The oil is refined into its constituents by a process called fractional distillation . This separates out the different constituents of crude oil by making use of the very fact that they boil off and vaporize at different temperatures. The first process is administered during a fractionating column, a tall cylindrical tower up to 250ft (75m) high, inside which are between 30 and 40 trays called fractionating trays, stacked one above the opposite . rock bottom of the column is kept extremely popular but the temperature drops the further you progress up the column, in order that each tray is slightly cooler than the one below it.

The petroleum is preheated to between 315°C and 370°C in order that all except the heaviest constituents vaporize. it’s then fed in towards rock bottom of the fractionating column as a mix of gas and liquid. The oil vapor rises up the column through devices, like bubble caps, within the fractionating trays which cause it to be thoroughly mixed with the liquid already there. The heavier, still-liquid oil passes right down to rock bottom of the column.

As the vapor rises it cools in line with the falling temperature of the trays. Whenever the vapor passes up to and bubbles through a tray containing liquid whose temperature corresponds to the boiling point of 1 of the constituents of the vapor, that constituent condenses out on the tray. The other, higher-boiling-point vapors keep it up up the column.

The fractions

In this way, each constituent within the vapor meets a tray on which it condenses out. The result’s a series of separated constituents, called fractions, which can be drawn faraway from the column through pipes. There are six main fractions. The lightest, which remains a gas when it reaches the top of the column, is named refinery gas and is used as a fuel by the refinery itself.

The rest is further processed in a further plant. The lightest of the resulting liquid fractions are very volatile and are used for blending into petrol. Then come naphtha (used for further processing into petrochemicals or alternatively for blending into petrol), kerosene (which is essentially paraffin), diesel oils and light and heavy oils used for industrial lubricating, then the heaviest fraction, bitumen, which is left as a residue.


The basic fractionation process divides up crude oil into its pure chemical hydrocarbons. But a number of these hydrocarbons are more valuable than others. especially , the demand for petrol is far greater than for bitumen, or indeed for diesel. So a number of the heavier fractions are converted at the petroleum refinery into petrol. this is often done by a process called cracking. Thermal cracking uses heat within the process, while catalytic cracking uses a chemical catalyst.

In thermal cracking the hydrocarbons are heated to between 450°C and 540°C at high pressure. The result is a low-grade fuel which is then refined again at higher temperatures and pressures to produce petrol of good enough quality to use in car engines. Catalytic cracking is more useful than thermal cracking since it gives a higher yield of useful products. By adding a catalyst (usually an aluminum-silica powder) to the oil during the per-heating phase, the heavy fractions are often broken into a mix of lighter ones, which are then fed into a fractionating column to be separated out. These light fractions then undergo further processes called conversion processes to supply the right mixture of hydrocarbons.

Petrol properties

These conversions are followed by treatment stages where the appropriate additives are introduced to form the blended petrol suitable for winter or summer use. To be useful for running internal combustion engines, petrol must have certain properties. It must burn smoothly within the engine over a good range of speeds and power outputs without detonation . This manifests itself by ‘knocking’ and, if allowed to persist, may result in serious engine damage. The petrol must have some readily volatile constituents which permit the engine to start out easily in cold weather. But the petrol must not be so volatile that it vaporizes too easily and causes a lock within the equipment , or maybe carburetor icing (see sideline, right).

The performance of petrol is gauged primarily by its octane number. to figure this out, the petrol is compared with two standard fuels of known performance called n-heptagon and ISO-octane, both of which are hydrocarbons. N-heptagon may be a poor fuel for internal combustion engines and causes heavy knocking; it’s an octane rating of 0. ISO_octane is that the opposite, a really top quality fuel, and has an octane rating of 100. If petrol has an octane rating of 90 this suggests that it gives a performance like a mix of 90 parts ISO-octane to 10 parts heptagon. Most car engines require petrol with an octane rating of between 90 and 100.

As an extra anti-knock measure, it’s still normal practice to feature a little quantity of tetra ethyl or tetra-methyl cause the petrol. However, this is often steadily being curtailed due to the poisonous nature of lead. The maximum amount of lead allowed in petrol was lowered from 0.4 to 0.15 grammes per liter in 1986, and unleaded petrol is beginning to appear on the ecu market. this is often petrol to which no lead compounds are added.


From the oil refinery, the petrol and diesel are transported to their garage and repair station outlets by road or rail specially designed tankers. The fuels are usually stored in under ground tanks below the forecourt at the purpose of sale – the filling station. Petrol and diesel fuels are stored in separate tanks, as are different grades of petrol, until they’re lifted to above ground level and metered for sale by the pumps.

How a petrol station works

Petrol pumps can normally call up fuel from any of the underground tanks and blend it to supply the users with whichever grade is required . However, leaded and unleaded petrol must not be mixed in order that they need separate tanks and pumps which must be clearly marked to show what they contain.


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