The oils produced by the above-mentioned devices are generally not directly available as commodities. In order to meet the requirements of the products, in addition to blending and adding additives, it is often necessary to further refine, remove impurities, and improve performance to meet actual requirements. Common impurities are compounds containing sulfur, nitrogen, and oxygen, as well as undesirable components such as waxes and gums mixed in oil. They can make the oil smelly, deep in color, corrode mechanical equipment, and difficult to store. Commonly used methods for removing impurities include acid-base refining, deodorization, hydrogenation, solvent refining, white clay refining, and dewaxing. Acid refining is the treatment of oils with sulfuric acid to remove certain sulfur compounds, nitrogen compounds and gums. Alkali refining is the treatment of oils such as gasoline, diesel, and lubricating oil with an aqueous solution of caustic soda to remove oxygenates and sulfides, and to remove sulfuric acid remaining during acid refining. Acid refining and alkali refining are often combined, so it is called acid-base refining. Deodorization is the production of steam, coal, and diesel oil for crude oil containing high sulfur, which produces malodor due to the presence of mercaptans. When the content of thiol is high, the oil will be gelatinous and difficult to store. It can be treated with an alkali solution and then oxidized with air in the presence of a catalyst. Hydrogenation is carried out in the presence of a catalyst at 300-425 ° C, 1.5 MPa pressure hydrogenation, can remove sulfur, nitrogen, oxygen compounds and metal impurities, improve oil storage properties and corrosivity, flammability, available For a variety of oil products. Dewaxing is mainly used to refine aviation kerosene, diesel and so on. The oil contains wax, which forms crystals of wax at low temperatures, affects flow properties, and is prone to plugging pipes. Dewaxing is very important for aviation oil. Dewaxing can be adsorbed by molecular sieves. The refining of lubricating oils often uses solvent refining to remove undesirable components to improve composition and color. Sometimes you need to dewax. The white clay refining is generally placed at the end of the refining process, and the harmful substances are adsorbed by clay (mainly composed of silica and alumina).
Acid refining
The oil is treated with sulfuric acid to remove certain sulfur compounds, nitrogen compounds and gums.
Alkali refining
The oil is treated with an aqueous solution of caustic soda, such as gasoline, diesel, and lubricating oil, to remove oxygenates and sulfides, and to remove sulfuric acid remaining during acid purification. Acid refining and alkali refining are often combined, so it is called acid-base refining.
Deodorization
It is a kind of steam, coal and diesel oil made from high-sulfur crude oil. It produces malodor due to the presence of mercaptan. When the mercaptan content is high, it will cause the oil to be colloidal and difficult to store. It can be treated with an alkali solution and then oxidized with air in the presence of a catalyst.
Hydrogenation
It is hydrogenated at 300~425°C and 1.5 MPa in the presence of catalyst to remove sulfur, nitrogen and oxygen compounds and metal impurities, improve oil storage performance, corrosion and flammability, and can be used in various Oil products.
Dewaxing
Mainly used to refine aviation kerosene, diesel and so on. The oil contains wax, which forms crystals of wax at low temperatures, affects flow properties, and is prone to plugging pipes. Dewaxing is very important for aviation oil. Dewaxing can be adsorbed by molecular sieves. Refinement of lubricating oils often uses solvent refining to remove undesirable components to improve composition and color. Sometimes you need to dewax.
White clay refining
At the end of the refining process, it is generally used to adsorb harmful substances using clay (mainly composed of silica and alumina).
lubricating oil
The raw materials are mainly derived from the distillation of crude oil. The most important properties of lubricating oil are viscosity, stability and lubricity. The basic process of producing lubricating oil is essentially to remove undesirable components in the feedstock oil, mainly colloids, asphaltenes and compounds containing sulfur, nitrogen and oxygen, as well as waxes, polycyclic aromatic hydrocarbons, which mainly affect viscosity, Stability, color. The methods include solvent refining, dewaxing and deasphalting, hydrogenation and white clay refining.
Solvent refining
It is the use of solvent to different solubility of different components to achieve the purpose of refining, which is used in most lubricant production processes. Commonly used solvents are furfural and phenol. The production process is similar to the aromatics extraction of the reformer.
Solvent dewaxing
It is a component which is easy to produce crystallization at low temperature in the raw material of lubricating oil, mainly refers to paraffin wax, and the cold crystallization method is used for dewaxing. In order to overcome the excessive viscosity at low temperature, the paraffin crystal is too small to be inconveniently filtered, and often has no dissolution effect on wax. A mixed solvent such as toluene-methyl ethyl ketone is often referred to as ketone benzene dewaxing.