Oil is a precious energy with high utilization value. It is the main component of global energy supply in this century, accounting for about 35% – 50% of the total. Petroleum products, as energy and chemical raw materials, are involved in various fields of national economy and national defense construction, and go deep into every link of people’s clothing, food, housing and transportation, becoming an important strategic material related to the national economy and people’s livelihood. Therefore, the refining industry that produces petroleum products has become one of the basic industries of the national economy.
Process of using water ring vacuum pump technology in oil refining process
There are four crude oil processing schemes: fuel type, fuel chemical type, fuel lubricating oil type and fuel lubricating oil chemical type.
Water ring vacuum pump technology in petroleum refining industry mainly embodies the following aspects:
1. Vacuum distillation
Crude oil distillation is the first process of crude oil processing, generally including atmospheric distillation and vacuum distillation. Crude oil can only obtain light oil (gasoline, kerosene, diesel oil, etc.) accounting for about 20% – 30% of the total crude oil under the charm part of atmospheric distillation, and the rest is atmospheric heavy oil. In order to produce more distillate oil as the secondary processing raw material without thermal cracking reaction of macromolecular hydrocarbon in heavy oil, vacuum distillation is used. As the boiling point of the substance decreases with the decrease of the external pressure, the high boiling point fraction (i.e. macromolecular hydrocarbon) will be gasified at a lower temperature by heating the atmospheric heavy oil at a lower pressure, so as to effectively separate the high boiling point fraction oil and residual oil with the boiling point lower than 500 and avoid cracking.
According to operation conditions, vacuum distillation can be divided into “wet” and “dry”. The so-called dry vacuum distillation, which does not rely on the injection of water vapor to reduce the partial pressure of oil and gas, is widely used for its low energy consumption and high extraction rate, while the wet vacuum distillation process is gradually replaced by the former.
For vacuum system, two-stage steam jet pump is used for wet distillation, and the residual pressure on the top of the tower is 3-5kpa. For dry vacuum distillation, the residual pressure on the top of the tower with three-stage steam jet pump can be reduced to 1-2kpa. The ratio between the total amount of each fraction obtained by distillation and the crude oil treatment capacity is called the total pullout rate. To improve the crude oil extraction rate is mainly to improve the extraction rate of the vacuum tower or the crude oil cutting depth. Under the same gasification temperature, the higher the vacuum degree is, the higher the oil gasification rate is, the higher the tower extraction rate is
2. Catalytic reforming, aromatics extraction
Catalytic reforming is an important secondary processing method in petroleum processing. It is used to produce gasoline with high octane number or aromatic hydrocarbon (benzene, toluene, xylene, etc.) as chemical raw material. When sulfolane is used for extraction, aromatics are separated from the solvent by vacuum distillation, and the top gas of the recovery tower is condensed and then enters the aromatics tank (the top of the tank is vacuumed by steam jet pump).
3. Solvent refining of lubricating oil
The amount of lubricating oil is not much, which accounts for a small proportion of petroleum products, but there are many kinds of lubricating oil, hundreds of them, and they often have different general processes of lubricating oil production with special requirements, such as raw material → refining → deasphalting → dewaxing and supplementary refining → post-treatment → blending.
The purpose of solvent refining is to remove harmful impurities, improve the performance of lubricating oil and meet the use requirements. The basic principle of solvent refining is to use the selective dissolving ability of some solvents to achieve the purpose of removing well ideal components from lubricating oil. No matter what solvent is used, the basic production process is composed of two parts: solvent extraction and solvent recovery. In the solvent recovery process, the recovery of refined liquid and the removal of residual solvent in the extraction liquid are all completed by vacuum distillation in the stripper cluster in the vacuum state.
The imported vacuum pump technology in petroleum refining industry is on the rise. A large number of vacuum equipment used in oil refineries are steam jet pumps, only a small number of mechanical vacuum pumps are used in some dry vacuum distillation towers and small refineries. With the development of the vacuum tower, the steam jet pump has become a behemoth. The contradiction of energy consumption, low efficiency and water pollution has become increasingly prominent.
In recent years, the pumping capacity of the imported vacuum pump has also been greatly improved, which is enough to meet the vacuum requirements of some small and medium-sized pressure reducing devices, solvent recovery devices and oil refining devices.