Supercritical solvent extraction deasphalting process in petroleum refining
The basic approach from crude oil to petroleum is generally:
1. Crude oil is first divided into different straight-run distillate oils according to the boiling point requirements of different products, and then the non-ideal components in these distillate oils are removed according to the product quality standards;
2, through the chemical reaction transformation, generate the required components, and then get a series of qualified petroleum products.
Solvent deasphalting is a common process flow for petroleum refining.
Solvent deasphalting is a pretreatment of poor residue. With the method of extraction, from the vacuum residue obtained from the distillation of crude oil (sometimes also from the atmospheric residue), the gum and asphalt are removed to prepare a petroleum product refining process for deasphalting oil and producing petroleum asphalt.
1. Raw materials: heavy oil such as vacuum residue or atmospheric residue
2, products: deasphalting oil, etc.
3. Basic concept: Solvent deasphalting is an oil refining process for processing heavy oils. The process uses heavy oils such as vacuum residuum as raw materials, and uses hydrocarbons such as propane and butane as solvents for extraction and extraction. The de-asphalted oil can be used as heavy lubricating oil raw materials or cracking raw materials, and the de-oiled asphalt can be used as road asphalt or other purposes.
4, production process
Includes extraction and solvent recovery. The extraction section generally adopts a section of extraction process, and can also adopt a two-stage extraction process.
The bitumen and heavy deasphalted oil solutions contain less propane. One-time evaporation and stripping are used to recover propane. The light deasphalting oil solution contains more propane. Multi-effect evaporation and stripping or critical recovery and stripping recovery of propane are used to reduce Energy consumption.
The critical recovery process uses propane at near critical temperature and slightly above the critical pressure (96.8°C of propane critical temperature, 4.2 MPa critical pressure). The solubility of the oil is close to the minimum and the density is also close to the minimum. The light deasphalting oil and most of the propane are settled and separated in the critical tower, thus avoiding the evaporative condensation process of propane, and therefore, the energy consumption can be reduced more.
The solvent deasphalting process in China mainly consists of a two-stage deasphalting process by sedimentation, a critical recovery deasphalting process, and a supercritical extraction solvent deasphalting process.
Two-stage deasphalting process by sedimentation: The two-stage deasphalting by the sedimentation method is developed on the basis of a conventional deasphalting basis. Based on the study of the unique properties of Daqing vacuum residue, we noticed that the conventional propane deasphalting can not make full use of this resource and developed a new deasphalting process.
Critical recovery deasphalting process: The solvent's ability to dissolve oil decreases with increasing temperature. When the temperature and pressure are close to critical conditions, the solvent's ability to dissolve oil has dropped to a very low level. At this time, the propane solvent is cooled. Can be used directly after recycling, without having to go through evaporation recovery.
Supercritical solvent extraction deasphalting process: Supercritical fluid extraction is the use of extraction system near the critical region with abnormal phase equilibrium characteristics and abnormal thermodynamic properties, by changing the temperature, pressure and other parameters, so that the components within the system Mutual solubility changes drastically to achieve component separation
5, production equipment
The function of the extraction tower is as follows: the extraction zone is between the residue oil import and the main solvent inlet, the residue above the residue oil import is the fractionation zone, and the main solvent inlet is the following asphalt settlement zone.
Solvent critical/supercritical recovery tower
A deasphalting oil solution separator, also known as a supercritical or critical column, is actually a liquid-liquid separator that can operate above the critical pressure of the solvent to recover the solvent in the deasphalted oil solution.
The deasphalted oil solution booster pump is the key equipment for realizing the supercritical solvent recovery process. It needs to have a head of more than 1.5Mpa, the inlet can withstand high pressure and temperature, and the role of the pump is to ensure that the solvent is circulated in the system.