The aromatics extraction unit can not only reduce the benzene content in gasoline, improve the quality of gasoline and protect the environment on which human beings depend; more importantly, it can provide high purity basic materials such as benzene, toluene, xylene and o-xylene to meet the growing needs of petrochemical industry and chemical fiber industry. Moreover, the extracted non-aromatic hydrocarbon products can also be used as raw materials for producing high quality solvent oil. This paper deals with an aromatics extraction process, especially in the field of oil refining and petrochemical industry.
The recovery tower in aromatics extraction unit is an important unit for producing aromatics products and recovering solvents. Due to the limitation of solvent degradation temperature, the recovery tower is generally designed to operate under negative pressure. In the past aromatics process packages, the vacuum system of recovery tower is mainly realized by steam jet pump, which consumes a lot of energy and produces a large amount of sewage in production, which is easy to pollute the environment. In recent years, with the improvement of equipment level in the petrochemical industry and the national attention to energy saving and emission reduction, dry vacuum system has gradually replaced the traditional wet system. Dry screw vacuum pump is widely used in Australian refining industry.
The dry vacuum pump system and the process steam do not pollute each other. The process steam can be directly removed from the tail gas treatment system after compression and pressurization by the dry screw vacuum pump. EVP vacuum pump manufacturer suggests that dry vacuum pump is the main vacuum scheme for aromatics extraction unit.
Why choose dry screw vacuum pump? What are its performance characteristics?
Performance characteristics of dry screw vacuum pump:
1. Clean vacuum can be obtained without any medium in the working chamber.
2. The working chamber and the surface of the screw rotor are coated with anticorrosive coating, which can adapt to the harsh working conditions.
3. The gas is not compressed in the pump, so it is suitable to extract condensable gas.
4. A single pump can be pumped from the atmosphere to 1Pa. The vacuum system can be greatly simplified.
5. Water temperature has little effect on vacuum, saving more than 90% water, even without water consumption.
6. No fuel consumption, no drip and leakage
7. There is no friction between rotating parts. It can run at high speed and the whole body is small.
8. The structure is simple and easy to maintain.
9. The pumped gas is directly discharged from the pump body, without polluting the water, without environmental protection pressure, and the gas recovery is more convenient.
10. Oil-free unit with Roots pump and molecular pump
From the performance characteristics of screw vacuum pump, it can be seen that the use of dry vacuum pump instead of steam jet pump in recovery system has remarkable energy saving and environmental protection effect, and the investment recovery period is short, which can create considerable economic and social benefits for the device. At present, the application of dry screw vacuum pump in aromatic hydrocarbon extraction process can reduce the discharge of benzene-containing wastewater and environmental pollution of the unit, and greatly reduce the operating cost, which lays a good foundation for the clean production of the unit after its commissioning.