From crude oil to oil, there are many processes, and different processes will produce the same raw materials .
The basic routes from crude oil to oil are generally:
1 The crude oil is first divided into different straight-run distillates according to the boiling point requirements of different products, and then the non-ideal components in the distillate are removed according to the quality standards of the products;
2 Conversion by chemical reaction to produce the desired components, which in turn yields a range of qualified petroleum products.
The common processes for petroleum refining are atmospheric and vacuum distillation, catalytic cracking, delayed coking, hydrocracking, solvent deasphalting, hydrorefining, and catalytic reforming.
1) Atmospheric and vacuum distillation
- Raw materials:
Crude oil, etc.
- Product:
Naphtha, gas oil (gas oil), residual oil, asphalt, minus one line.
- Basic concepts:
Atmospheric and vacuum distillation is a combination of atmospheric distillation and vacuum distillation. It is basically a physical process: the feedstock oil is divided into oils with different boiling points (called fractions) according to the evaporation capacity in the distillation tower. Some of these oils are blended. After adding the additive, it is delivered as a product, and a considerable part is the raw material of the subsequent processing device.
Atmospheric and vacuum distillation is the first process of oil processing in refinery, called primary processing of crude oil, including three processes: a. desalting and dehydration of crude oil; b. atmospheric distillation; c. vacuum distillation.
- Production process:
Crude oil generally has salt and water, which can cause corrosion of equipment. Therefore, crude oil is first subjected to desalting and dehydration pretreatment before entering atmospheric and vacuum, usually by adding demulsifier and water.
Crude oil is formed into two parts through a flow meter, a heat exchange part, and a distillation tower. A part of the oil forms a top oil, passes through a cooler, a flow meter, and finally enters the tank area. This part is a chemical light oil (so-called naphtha); Forming the bottom oil, and then passing through the heat exchange part, entering the atmospheric pressure furnace and the atmospheric pressure tower to form three parts, a part of diesel oil, a part of wax oil, and a part of bottom oil; the remaining bottom oil is passed through a vacuum furnace, a vacuum tower Further processing, generating a minus line, wax oil, residual oil and asphalt.
The respective yields: naphtha (light gasoline or chemical light oil) accounted for about 1%, diesel accounted for about 20%, wax oil accounted for about 30%, residual oil and asphalt accounted for about 42%, and reduced one line accounted for about 5%. about.
The atmospheric and vacuum distillation process does not produce gasoline products, in which wax oil and residual oil enter the catalytic cracking process to produce gasoline, diesel, kerosene and other refined oil products; naphtha is directly sold by other small enterprises to produce solvent oil or to further processing in the next step. It is generally used to produce solvent oil or extract extract compounds by catalytic reforming;
- Production equipment:
The atmospheric and vacuum distillation device is a distillation device for processing crude oil once, that is, a crude oil is fractionated into a processing device for components such as gasoline, kerosene, diesel oil, wax oil, and residual oil. Crude oil distillation generally includes two parts of atmospheric distillation and vacuum distillation.
- Atmospheric distillation tower
The atmospheric distillation of crude oil is the distillation of crude oil at normal pressure (or slightly higher than normal pressure). The distillation equipment used is called crude oil atmospheric distillation column (or atmospheric pressure column).
The heavy oil component remaining under atmospheric distillation has a large molecular weight, a high boiling point, and is easily decomposed at a high temperature, which deteriorates the distilled product and produces coke, which destroys normal production. Therefore, in order to extract more light components, the boiling point range of the distilled feedstock oil is often lowered by lowering the distillation pressure. This distillation process under reduced pressure is called vacuum distillation.
- Vacuum distillation tower
The vacuum distillation is a distillation process carried out under a negative pressure of less than 100 KPa. The core equipment for vacuum distillation is a vacuum tower and its vacuum system.
The vacuum pumping equipment of the vacuum tower is usually a steam injector (also called a steam suction pump) or a mechanical vacuum pump. Among them, the mechanical vacuum pump is only used in some dry vacuum distillation towers and vacuum towers of small refineries, and steam injectors are widely used.
(2) Catalytic cracking
Generally, crude oil obtained by atmospheric and vacuum distillation can be obtained from gasoline, kerosene and diesel oil, such as 10 to 40%, and the rest are heavy distillate and residual oil. If you want more light oils, you must reprocess the heavy and residual oils. Catalytic cracking is the most common production process for producing gasoline and diesel. Gasoline and diesel are mainly produced through this process. This is also the most important production link for general petroleum refining companies.
- Raw materials:
Residual oil and wax oil are about 70%. Catalytic cracking is generally based on vacuum distillate oil and coking wax oil. However, with the increasing crude oil and the increasing demand for light oil, most of the refining and chemical enterprises have begun. The vacuum residue is added to the raw material, and even the atmospheric residue is directly used as a raw material for refining.
- Product:
Gasoline, diesel, oil slurry (heavy distillate), liquid propylene, liquefied gas; each accounted for 42% of gasoline, diesel accounted for 21.5%, propylene accounted for 5.8%, liquefied gas accounted for 8%, and slurry accounted for 12%.
- Basic concepts:
Catalytic cracking is the main process for processing heavy oil (such as residue) into light oil (gasoline, kerosene, diesel) in the presence of a catalyst. It is the main secondary processing method in the refining process. Belongs to the chemical processing process.
- Production process:
The normal slag and the wax oil enter the riser, the settler and the regenerator through the feedstock buffer tank to form oil and gas, and enter the fractionation tower.
A part of the oil and gas enters the crude gasoline tower, the absorption tower, and the air compressor enters the condensed oil tank, passes through the re-absorption tower, the stabilization tower, and finally performs gasoline refining to produce gasoline.
A part of the oil and gas passes through the fractionation tower and enters the diesel stripper, and then the diesel is refined to produce diesel. A part of the oil and gas passes through the fractionation tower and enters the slurry circulation, and finally the oil slurry is produced.
A part of the oil and gas enters the liquid hydrocarbon buffer tank through the fractionation tower, and passes through the desulfurization adsorption tank, the sand filter tower, the water washing tank, the desulfurization alcohol extraction tower, the pre-alkaline washing tank, the amine liquid recovery unit, the desulfurization extraction tower, the buffer tower, and finally enters the liquid state. A hydrocarbon tank forms a liquefied gas.
A part of the oil and gas enters the depropanizer, reflux tower, deethanizer, propylene column, reflux tank through the liquid hydrocarbon buffer tank, and finally enters the spheroidal tank of the propylene zone to form liquid propylene.
The liquid propylene is further processed by the polypropylene workshop to produce polypropylene.
- Production equipment:
- Regenerator
The primary function of the regenerator is to burn off the coke on the coked catalyst to restore the activity of the catalyst while also providing the heat required for cracking. The regenerator consists of a casing, a cyclone, an air distributor, a secondary combustion chamber and a heat extractor.
- Riser reactor
Straight pipe type: It is mostly used for high and low side-by-side anti-re-rear system. It is characterized by direct insertion from the bottom of the settler, simple structure and small pressure drop.
Folding type: mostly used for coaxial anti-re-system.
- Settler
The function of the settler is to separate the reaction oil and gas from the riser and the catalyst. The oil and gas are separated from the entrained catalyst by the cyclone and then passed through the gas collection chamber to the fractionation system; the catalyst from the rapid separator falls down by gravity in the settler. , falling into the gas section.
- Three machines
Main fan: Supply regenerative scorch air.
Air press: used to boost the rich gas from the fractionation system and then sent to the absorption stabilization system.
Supercharger: Supply the type IV reaction regeneration unit dense phase riser to adjust the catalyst circulation amount.
- Three valve
Single-acting slide valve: In the type IV catalytic cracking unit, it is fully open during normal operation, closed in an emergency, and the two devices are disconnected to prevent backflow of the catalyst; the circulation of the two catalysts is adjusted in the riser catalytic cracking unit.
Double acting slide valve: installed between the regenerator outlet and the venting chimney, adjusting the pressure of the regenerator to maintain the pressure balance of the two devices.
Plug valve: The amount of circulation of the catalyst is adjusted in a coaxial catalytic cracking unit.
