Addtime： 2020-07-18 Browse times： 1995
Vacuum pumps include dry screw vacuum pump, water ring pump, reciprocating pump, slide valve pump, vane pump, roots pump and diffusion pump. These pumps are essential main pumps in the application of vacuum technology in various industries of China's national economy. In recent years, with the sustained and rapid development of China's economy, the vacuum pump related downstream application industry has maintained a rapid growth momentum. At the same time, driven by the continuous expansion of vacuum pump application field and other factors, China's vacuum pump industry has achieved sustained, stable and rapid development.
1. Very low vapor pressure: This is the most important performance of vacuum pump oil. Since vacuum pump requires high vacuum degree, paraffin based narrow fraction lubricating oil is generally used. For diffusion vacuum pump, silicone oil with low vapor pressure or other synthetic oil can also be used.
2. Proper viscosity and good viscosity temperature characteristics: the volume of vacuum pump cavity changes constantly and forms exhaust effect, so lubricating oil should have appropriate viscosity and viscosity temperature characteristics.
3. Good thermal oxidation stability: vacuum pump is developing to a high speed. Due to the high-speed friction between sliding vane and pump body, the oil temperature increases, and the oil is easy to be oxidized and decomposed. Especially, the diffusion pump is often in a very high temperature environment, which increases the vapor pressure in the system and reduces the vacuum degree. Therefore, the vacuum pump oil is required to have good thermal oxidation stability.
4. Good corrosion resistance and oxidation resistance: if the gas inhaled by vacuum pump is corrosive, it will react with oil and corrode the internal parts of the pump; there is often water vapor condensate in the air inhaled, which will cause emulsification of vacuum pump oil and corrosion of metal, so it is required to have good corrosion resistance and demulsibility.
5. High flash point: the vacuum pump should not carry light components to avoid affecting the saturated vapor pressure of oil.
6. Lower limit pressure: limit pressure is an important performance index of vacuum pump oil to understand the limit pressure of vacuum pump under the lowest vacuum limit pressure.
Vacuum pump refers to the device or equipment that uses mechanical, physical, chemical or physicochemical methods to extract air from the container to obtain vacuum. Generally speaking, vacuum pump is a device to improve, generate and maintain vacuum in a certain closed space by various methods. According to the working principle of vacuum pump, vacuum pump can be basically divided into two types, namely gas capture pump and gas transfer pump. It is widely used in metallurgy, chemical industry, food, electronic coating and other industries.
Steam pressure: low steam pressure and pressure fluctuation have a great impact on the capacity of vacuum pump, so the steam pressure should not be lower than the required working pressure. However, the structural design of the vacuum pump used has been finalized. Increasing the steam pressure too much will not increase the pumping capacity and vacuum degree. In addition, to ensure that the steam pressure supplied by the boiler is stable, it is better to use a boiler to provide working steam for the steam jet pump, so that the steam pressure will not fluctuate and the performance of the vacuum pump will be stable.
Circulating cooling water: if the cooling water supply is insufficient, the condenser will generate heat, the sound of air flow will increase, the vacuum degree will drop rapidly, and even the steam will return to the suction pipe. Condensate plays an important role in multi-stage vacuum pump. Condensate can condense steam fully. The partial pressure of water vapor in the discharge pressure of vacuum pump must be higher than the corresponding full steam pressure. Therefore, the temperature of condensate water should be lower than the full temperature under the pressure to ensure the normal operation of the pump body.
Nozzle: the nozzle is an important part that affects the performance of vacuum pump. The existing problems are: the nozzle is installed incorrectly, installed Skewly, blocked, damaged, corroded and leaked. No matter what preventive measures are taken, the nozzle blockage is inevitable. On the one hand, when the steam pipe is installed, the residual iron chips and welding slag in the pipe will block the nozzle; on the other hand, when the vacuum pump system is stopped, the steam pipe is easy to rust, and the rust spots fall down and block the nozzle when using.
Service environment: the environmental impact mainly refers to the pollution of the system caused by the extracted gas. In the process of liquid steel disposal, a lot of gas will be released from the molten steel. At the same time, some small particles such as oxide scale will be sucked into the vacuum pump. These small particles will accumulate and adhere to the pump body, which reduces the flow conductivity of the suction pipeline, prolongs the pumping time and reduces the pumping function of the pump.
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