Asphalt production technology

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1. It is impossible to directly produce qualified road asphalt by distillation method from almost all waxy crude oils, and it is also difficult to produce qualified construction asphalt by oxidation method. The main problem is that the wax content is too high. Solvent deasphalting technology is used to treat vacuum residual oil. After one or two stages of extraction, while obtaining lubricating oil or catalytic cracking feed, low-wax deoiled asphalt can be obtained. This deoiled asphalt has the potential to directly produce road asphalt products that meet specifications. As the blending component powder, vacuum residual oil, vacuum distillate oil, lubricating oil solvent refined extracted oil, catalytic oil slurry, waste engine oil, etc. can be used. Therefore, using deoiled asphalt as the basic component and then blending it with various components expands the oil source for producing asphalt products, increases the variety of asphalt products, and improves the quality of asphalt products. Therefore, it can best make full use of my country's abundant waxy crude oil resources. From the late 1970s to the 1980s, my country's petroleum refining research and production and utilization departments have cooperated comprehensively and long-term, clarifying the possibility of producing asphalt from various waxy crude oils, proposing reasonable processing routes, and verifying them through production and use practices. The solvent method can be used to directly obtain the waxy crude oil content of qualified road asphalt products.: Daqing, Fuyu, Erlian, Shengli, Linpan, Xinjiang Baik blend and other crude oils ； There are few crude oils that can directly obtain qualified construction asphalt products, only Daqing, Fuyu, Shengli and other crude oils. Flexibility to produce qualified asphalt products if deoiled asphalt is blended with other components * * To improve, the key is to control the appropriate distillation depth, solvent deoiling depth and select suitable blending components. Then you can blend a variety of products that comply with GB/T15180 heavy traffic road asphalt or SH0522 road petroleum asphalt. ； However, blended construction asphalt is still limited by oil sources. The deoiled asphalt from Xinjiang Baik mixed crude oil can be directly oxidized or mixed with other components and then oxidized to produce a variety of special asphalts such as cable asphalt, battery sealant, insulating asphalt, and body coating asphalt. The product quality fully meets the specifications of industry standards. 2. Distillation-semi-oxidation combined process The distillation method can directly produce road asphalt from most intermediate bases, naphthenic-intermediate bases and naphthenic bases. However, the distillation temperatures of asphalt with the same penetration degree produced from different oil sources are different. The distillation temperature is related to the density, viscosity, fraction composition and chemical composition of crude oil. There are not many crude oils that can directly produce road asphalt with a penetration of 40-120 at a distillation temperature below 480°C (converted to normal pressure). For example, when asphalt with a penetration of 100 is produced from Shanjiasi heavy oil, its distillation cutting temperature is 438°C, and Suizhong 36-1 crude oil is 465°C.℃ ； When the crude oils of Huanxiling, Gudao, Karamay 9th District and Yangsanmu are 510, 515, 520 and 525℃ respectively, it is difficult to achieve it by ordinary vacuum distillation. In order to produce various grades of road asphalt from similar heavy oils, it is best to use a combined distillation and semi-oxidation process. By reasonably adjusting the depth of distillation and semi-oxidation, production and product variety and quality can be flexibly controlled. The chemical composition of asphalt undergoes certain changes after semi-oxidation. The asphaltene increases, which is beneficial to increasing the viscosity of asphalt and correspondingly improving the heat resistance, viscoelasticity and temperature sensitivity. Therefore, semi-oxidation is an effective means to adjust the chemical composition of asphalt to produce high-viscosity road asphalt. At present, heavy oil such as Huanxiling, Jiuqu, Suizhong 36-1 and imported Kuwait crude oil use this combined process to produce various brands of heavy traffic road petroleum asphalt, and have formed a considerable scale of production capacity. 1. Distillation method: The crude oil is distilled under normal pressure to separate light fractions such as gasoline, kerosene, and diesel, and then the vacuum distillate is separated through vacuum distillation (residual pressure 10~100mmHg). When the remaining residue meets the specifications of road asphalt, asphalt products can be directly produced. The resulting asphalt is also called straight-run asphalt, which is the main method for producing road asphalt. 2. Solvent precipitation method: Non-polar low-molecular-weight alkane solvents have different solubilities for each component in vacuum residue oil. The difference in solubility can be used to achieve component separation. Therefore, components that are detrimental to asphalt properties can be removed from vacuum residue oil and produce asphalt products that meet specifications. This is the solvent precipitation method. 3. Oxidation method: Air is blown into vacuum residue or deoiled asphalt at a certain range of high temperatures to change its composition and properties. The resulting product is called oxidized asphalt. Vacuum residual oil will vaporize and evaporate under the action of high temperature and blowing air, and at the same time, a series of reactions such as dehydrogenation, oxidation, polymerization and condensation will occur. This is a very complex comprehensive reaction process in which multiple components interact with each other. It is not just an oxidation reaction, but * Conventionally called oxidation method and oxidized asphalt, it is also called air blowing method and air blown asphalt. 4. Adjustment method: The production of asphalt by the blending method initially refers to the re-blending of the four components of asphalt composed of the same crude oil in the proportion required by the quality requirements. The resulting product is called synthetic asphalt or reconstructed asphalt. With the development of process technology, the sources of blending ingredients have expanded. For example, residues or components from primary and secondary processing of the same crude oil or different crude oils, as well as various industrial waste oils, can be used as blending components, which reduces the dependence on oil source selection in asphalt production. With the increasing shortage of crude oil suitable for making asphalt, the flexibility and economy shown by the blending method are increasingly being valued and widely used. 5. Emulsification method: The surface tensions of asphalt and water are very different and they are not miscible with each other at normal or high temperatures. However, when asphalt is subjected to mechanical action such as high-speed centrifugation, shearing, and impact, it becomes particles with a particle size of 0.1 to 5 μm, and is dispersed into a water medium containing a surfactant (emulsifier-stabilizer). Since the emulsifier can be directionally adsorbed on the surface of the asphalt particles, the interfacial tension between water and asphalt is reduced, allowing the asphalt particles to form a stable dispersion system in the water. This is an oil-in-water emulsion. This dispersion system is brown in color, with asphalt as the dispersed phase and water as the continuous phase, and has good fluidity at room temperature. In a sense, emulsified asphalt "dilutes" the asphalt with water, thereby improving the fluidity of the asphalt. 6. Modified asphalt: Modern highways and roads undergo many changes: Traffic flow and driving frequency have increased dramatically, the axle load of freight trucks has continued to increase, and one-way driving in separate lanes has been widely implemented, requiring further improvement of road surface flow resistance, that is, the ability to resist rutting under high temperatures. ； Improve flexibility and elasticity, i.e. the ability to resist cracking at low temperatures ； Improve wear resistance and extend service life. Modern buildings generally use long-span prestressed roof panels, which require roof waterproofing materials to adapt to large displacements, be more resistant to harsh high and low temperature climate conditions, have better durability, have self-adhesiveness, facilitate construction, and reduce maintenance workload. These changes in the use environment pose severe challenges to the performance of petroleum asphalt. Modification of petroleum asphalt to adapt to the above-mentioned harsh usage requirements has attracted people's attention. After decades of research and development, a wide variety of modified road asphalt, waterproof membranes and coatings have emerged, showing certain practical engineering effects. However, given that the price of modified asphalt is usually 2 to 7 times higher than that of ordinary petroleum asphalt, users have not yet fully grasped the engineering performance of the material, and the output of modified asphalt has grown slowly. At present, modified road asphalt is mainly used for paving applications in special occasions such as airport runways, waterproof bridge decks, parking lots, sports fields, heavy traffic pavements, intersections and road turns. Recently, modified asphalt has been applied to the maintenance and reinforcement of road networks in Europe, which has greatly promoted the widespread application of modified road asphalt. Modified asphalt waterproofing membranes and coatings are mainly used in waterproofing projects for high-end buildings. With the advancement of science and technology and the development of economic construction, the variety development and production technology of modified asphalt will be further promoted. The variety and preparation technology of modified asphalt depend on the type and amount of modifier and the composition and properties of the base asphalt (i.e. raw asphalt). Due to the wide variety of modifiers with different forms, in order to form a uniform material with petroleum asphalt that can be used for engineering applications, various types of modifiers have been evaluated over the years and corresponding formulas and preparation methods have been developed. However, most of the modified asphalts that have been used in engineering applications belong to patented technologies and patented products.