What are the practical methods of dry screw vacuum pump in industry?

I. Dry Screw Vacuum Pump for Solvent Recovery in Pharmaceutical Industry
The bulk drug selected from the solvent crystallization method is usually filtered after crystallization, washing and vacuum drying. The moisture content of materials is usually 20% to 200%. Solvents in wet materials are usually flammable, explosive, toxic and harmful media, which are vacuum-pumped during drilling.
Roots-liquid ring vacuum pump is used in traditional wet vacuum system. Sealant for liquid seal pump dissolves or absorbs some organic solvents during operation, and separates waste gas and high concentration organic waste liquid in vapor-liquid separator. Some of them need to be addressed. This will not only not completely recover this part of the solvent, but also increase the company's operating costs, bringing health, safety and environmental protection to the battle; dry vacuum condensation system can discharge organic solvents in the boring process. Because there is no other process medium in the pump chamber of the screw pump, the internal coating anti-corrosion method is adopted, which is energy-saving and environmental protection. Therefore, side condensation, complete solvent recovery, zero discharge of waste liquid. Solvents can be completely recovered without waste disposal problems. Therefore, screw vacuum pump has become an excellent choice in this field.
Secondly, dry screw vacuum pump is applied to gasoline vapor recovery in petrochemical industry
Dry screw vacuum pump is the key equipment of gasoline steam recovery equipment. The pumped gas is simply gasoline vapor. The main components are gasoline vapor, such as C4, C5 and C6.
Usually, the working temperature of the pump is controlled below 80 degrees C. However, by relying on jacket cooling, the cooling of the pump can not be reduced to such a low temperature. Most stations do not have cooling water. The coolant available is gasoline. In order to reduce the working temperature of the pump, besides introducing gasoline into the jacket of the pump body, the most useful method is to inject appropriate amount of gasoline into the pump chamber (at the highest temperature) to absorb the evaporative heat to reduce the temperature in the pump chamber.
As the screw vacuum pump is in the process of oil vapor recovery, the condensed gasoline will accumulate in the exhaust port of the pump. This cumulative phenomenon can cause abnormal oscillation and noise of the pump, so it must be discharged in time. Improvement methods.
1. The exhaust pipe of the pump inclines downward, and the direction of the exhaust pipe is lower than the direction of the exhaust port of the pump.
2. Install a circulating pump at the lowest point of the exhaust port or muffler of the pump to eliminate liquid accumulation.
3. Install a check valve at the outlet of the pump to prevent condensate from siphoning into the pump chamber during stopping operation.
3. Application of dry screw vacuum pump in space imitation
Because the volume of space analog pumping vessel varies from several thousand cubic meters to tens of thousands of cubic meters, the vacuum degree changes from tens of thousands of Pa to several Pa, and the pumping gas contains a large amount of water vapor or part of nitrogen oxide, the first problem encountered in this vacuum system is pre-vacuum. If the traditional slide valve is used as the front pump, the following problems exist:
First, the sliding valve operates for a long time under high inlet pressure. Due to the air flow effect, fuel injection is very serious. One is to destroy a lot of expensive oil, the other is to pollute the environment.
Because the pumped gas contains a lot of water vapor or nitrogen oxides, once the gas enters the pump, the vacuum pump oil will emulsify and deteriorate, the oil seal will be damaged, the vacuum function will be reduced, and the pump will be destroyed.
The number of pumps required by the equipment is very large, and the vibration and noise of the valve core pump are also very large. The screw vacuum pump has the advantages of clean, oil-free, high pumping speed, low vibration and low noise, and has become the first choice of large space simulation vacuum system. In addition, two-stage unit or two Roots pumps and screw vacuum pumps, as well as Roots pumps and screw vacuum pumps, are commonly used in order to improve the pumping speed and limit vacuum degree of vacuum devices and reduce the size of screw pumps. A three-level unit consisting of three series of connections. In order to prevent particulate impurities from entering the pump, the inlet of the vacuum device is equipped with an inlet filter with an accuracy of 50 microns.
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