The Correct Use of Roots Vacuum Pump
Roots vacuum pump is widely used in the key parts of the paper consumption process, such as the web part of the paper machine, the vacuum couch, the vacuum press, the wool dehydration, etc. The output of roots pump directly affects the output and quality of paper. When the flow rate and vacuum degree decrease, it will cause the moisture change of the paper page and form the paper defects such as sticking roller and embossing in the consumption process. Therefore, it is very important to use roots pump well.
1、 Adjust the clearance between impeller and rotor frequently
As we all know, roots pump is a kind of vacuum pump caused by the change of volume caused by the meshing of two “8-shaped” relative rotating rotors, so it is also called volume pump. There must be a continuous contact line at the place where the rotor of the pump is required to engage during the operation to prevent the gas from the exhaust port from flowing back to the vacuum pump. Therefore, it is necessary to check the engagement of the two rotors frequently. With the extension of operation time, the impeller has been worn for a long time, but also limited by the directional rotation, resulting in uneven meshing clearance between the two impellers, resulting in a collision, resulting in a concave surface of the impeller. Therefore, the outer diameter and length of the two impeller rotors have different levels of wear, and the clearance between the impeller rotors and the shell also increases. Thus, the vacuum degree of roots pump is reduced, and the time is large and the time is small. It is necessary to maintain and adjust the clearance between the impeller and the end cover and the pump housing in time.
If the clearance between the impeller and rotor is too small, the contraction ratio in roots pump will increase, which will cause the air in the pump to heat up, and soon lead to the heating of gearbox and motor. The reason why the gap between the two impellers becomes smaller is that additives, fillers, rubber and other substances are attached to the surface of the impellers. When this phenomenon occurs, the two rotors become too tightly meshed and even stuck. It is very difficult or basically does not rotate when it is restarted after shutdown, and the motor is burnt out sometimes. Therefore, it is necessary to clean the inner wall of the pump casing and the surface of the impeller rotor. The cleaning solution can be 5% sodium hydroxide solution or 5% hydrochloric acid solution. After acid cleaning, rinse with clean water to avoid corrosion.
(ULVAC RDA series multistage roots vacuum pump)
2、 Check the sealing condition of pump shaft frequently
The sealing function of the pump shaft is to prevent the compressed gas in the pump from leaking out between the pump shaft and the pump housing, and at the same time to prevent the external air from entering the pump. Mechanical seal and anti spiral seal, asbestos packing seal and rubber seal ring are often used. The mechanical seal effect is good.
3、 Reasonable selection of rotations of roots pump
In the application of roots pump, its revolution must be adjusted according to the practical demand. Obviously, the improvement of revolution can increase the theoretical exhaust volume, increase the volumetric efficiency, and increase the output significantly, but the resulting increase in noise will worsen the operating environment. When it is necessary to increase the number of revolutions in consumption to improve the ability of the pump, it shall be adjusted within the allowable range of workshop noise. Generally, the method of progressive revolution is not used. When the pumping speed of the pump is higher than the rated operating value, in addition to stop adjustment with the bypass valve, the speed shall be reduced and the reactive power consumption shall be reduced. In this way, for the equipment itself, it can reduce the production problems of the machine, reduce the vibration, increase the power storage and reduce the overload so as to improve the operating environment and reduce the noise at the same time.
4、 Series application of Roots vacuum pump
In consumption, two pumps are often used in series because the output of the pump can not meet the requirements. The high efficiency working area of ordinary roots pump is between – 300 and – 400mmhg column. To reach above – 500mmhg column, the vacuum degree of single pump is difficult to complete, so two pumps can be used in series. In accordance with the series connection mode adopted in this process, the pump placed at the front should play a pre pumping role, and the pumping speed of the pump at the back must be 1.5-2 times higher than that of the pump at the front. Only in this way can we play our due role.
Overseas Roots pumps in series use not only two pumps of the same type but also two pumps of different sizes, which still make the capacity of the front suction pump small and the capacity of the rear suction pump large. They are designed to be coaxial transmission, so that the coaxial compensation, the current change of the two pumps is small and the operation is convenient.
