(1) Application of screw vacuum pump in solvent recovery in pharmaceutical industry

Apis using a solvent crystallization process are usually filtered, washed, and vacuum dried after crystallization. The moisture content in the material is usually 20%~200%. The solvent contained in the wet material is usually flammable, explosive, toxic and harmful medium, which is pumped away by the vacuum unit in the drying process.

Traditional wet vacuum system generally choose roots - liquid ring vacuum pump unit, in the operation of the liquid ring pump sealing fluid in will dissolve or absorb part of the organic solvent, separation of waste gas in the vapour liquid separator and a high concentration of organic waste liquid, the two parts are need to deal with, it is not only this part is not fully recycled solvent, and increase the enterprise operation cost, more safety and environmental challenges to health; And application of dry type vacuum condensate system, can make the drying process of the organic solvent in the exhaust lateral condensation, implementation of solvent recovery, and waste water zero discharge of liquid waste, because of the progressive cavity pump cavity medium without any other process, internal surface coating anticorrosive measures, both energy saving and environmental protection, no liquid waste processing problems, solvent can also be all recycled. So screw vacuum pump has become the best choice in this application field.

 

(2) Application of screw vacuum pump in gasoline vapor recovery in petrochemical industry

Dry screw vacuum pump is a key equipment in the gasoline steam recovery device. The gas pumped is volatile gasoline steam, mainly composed of C4, C5, C6 and other gasoline steam.

Generally, the operating temperature of the pump is required to be controlled below 80℃. However, the operation of the pump cannot be reduced to such a low temperature only by cooling the jacket of the pump body. In addition, most of the sites cannot provide cooling water, and the coolant that can be provided is gasoline. In order to reduce the operating temperature of the pump in addition to the pump body jacket through the gasoline, the most effective way is to pump chamber (at the highest temperature) into an appropriate amount of gasoline, in order to reduce the pump chamber temperature by evaporation absorption.

In the process of oil and vapor recovery of screw vacuum pump, the condensed gasoline will be piled up at the exhaust outlet of the pump. This liquid accumulation phenomenon will cause abnormal vibration and noise of the pump, so it must be discharged in time. For this reason, the following three improvement measures can be taken.

Measure 1: the exhaust pipe of the pump tilts downward and the exhaust pipe is lower than the exhaust port of the pump.

Measure 2: Install a circulating pump at the lowest vent or muffler of the pump to eliminate effusion.

Measure 3: Install a check valve in the exhaust port of the pump to prevent the condensation flowing backward into the pump chamber due to the siphon phenomenon when the pump stops running.

 

(3) Application of screw vacuum pump in space simulation

Because of the space simulator on being the container from several thousand cubic meters to tens of thousands of cubic meters, the volume of vacuum degree change from tens of thousands of Pa to several Pa, and is pumped gas contains a large amount of water vapor or part of the nitrogen oxide, so this kind of vacuum system is the first problem is vacuum problem, if use the traditional plunger pump as a backing pump has the following problems:

Firstly, the slide valve pump operates for a long time under high inlet pressure. Due to the role of air flow, its oil injection is very serious.

Due to the large amount of water vapor or nitrogen oxide in the pumped gas, once these gases enter the pump, the vacuum pump oil will be emulsified and deteriorated rapidly, and the sealing of the oil will be damaged, leading to the deterioration of the vacuum performance, or even the destruction of the pump;

Need to configure the number of pumps, and the slide valve pump vibration, noise is also large;

Screw vacuum pump has become the first choice for large space simulation vacuum system due to its advantages of clean, oil-free, high pumping speed, low vibration and low noise. In addition, in order to improve the pumping speed and limit vacuum of the vacuum unit and reduce the size of screw pump accordingly, it is generally adopted a two-stage unit consisting of one Roots pump and screw vacuum pump in series or a three-stage unit consisting of two Roots pump and screw vacuum pump in series. In order to prevent particles and impurities from entering the pump, the inlet of the vacuum unit is equipped with an inlet filter with an accuracy of 50 m.