Roots vacuum pump is widely used in the key parts of paper consumption process, such as the network of paper machine, vacuum volt roll, vacuum pressing, wool dehydration and so on. The output of roots vacuum pump has a direct impact on the yield and quality of paper. When the flow rate falls and the vacuum degree decreases, it will cause the moisture change of the paper, forming paper diseases such as sticking rolls and embossing in the process of consumption. Therefore, roots vacuum pump operation is very important.
Adjust the clearance between impeller and rotor frequently:
As we all know, roots vacuum pump is a kind of vacuum pump caused by the volume change caused by the meshing of two “8-shaped” rotors, so it is also called the volume pump. During operation, a continuous contact line must exist at the part where the rotor of the pump is required to engage in order to prevent the exhaust gas from flowing back into the vacuum pump. Therefore, the meshing of the two rotors must be checked regularly. With the prolongation of operation time, the impeller wears for a long time and is restricted by directional rotation, resulting in uneven meshing clearance between the two impellers, and even collision, resulting in an isolated external depression of the impeller. As a result, the two impeller rotors have different levels of wear in outer diameter and length, and the clearance between the impeller rotors and the shell also increases. As a result, the vacuum degree of roots vacuum pump is reduced and the time is large and small. It is necessary to repair and adjust the clearance of the impeller and the gap between the end cover and the pump shell in time.
If the clearance between impeller and rotor is too small, it will increase the contraction ratio in roots vacuum pump, cause the air in the pump to heat up, and quickly cause the gear box and motor to heat up. Two the reason for the smaller clearance of impeller rotor is that the additives, fillers, and rubber materials are attached to the surface of the impeller. When this phenomenon occurs, the engagement between the two rotors becomes too tight to jam. It is very difficult to start up after shutdown or not to turn at all. Sometimes the motor will be burned out. Therefore, it is necessary to wash the inner surface of the pump and the surface of the impeller frequently. The cleaning solution can be washed with 5% sodium hydroxide solution or 5% hydrochloric acid solution, and then rinsed with clean water after pickling to avoid corrosion.
Check the sealing status of pump shaft regularly:
The sealing function of the pump shaft is to avoid the leakage of compressed gas from the pump shaft to the pump housing, and to avoid the immersion of external air into the pump. Mechanical seals and anti spiral seals, asbestos packing and rubber seals are often used. The mechanical seal has the best effect. Recently, the magnetic powder seal developed by Northeast University of technology has a good effect.
Rationally select the number of roots vacuum pump:
In the application of roots vacuum pump, we must adjust its revolutions according to practical needs. Obviously, the progress of revolution can increase theoretical exhaust volume, increase volumetric efficiency and output, but the resulting increase in noise will worsen the operating environment. When it is necessary to increase the speed of consumption to improve the ability of pumps, it should be adjusted within the allowable range of noise in the workshop. Progressive revolutions are usually not used. When the pump pumping speed is higher than the rated operating value, besides stopping adjustment with bypass valve, it should also reduce the speed and reactive power consumption. In this way, for the equipment itself, it can reduce faults, reduce vibration, increase power storage, improve overload ability, improve operating environment and reduce noise.
Series application of Roots vacuum pump:
In consumption, the two pumps are often used in series because the pump output can not reach the request. The high efficiency working area of ordinary roots vacuum pumps is between – 300 and – 400 mmHg columns. To reach above – 500 mmHg columns, the vacuum degree of a single pump is difficult to complete, so two pumps can be used in series. The series connection method adopted to comply with this process should make the pump in front play a pre-pumping role, and the pumping speed of the pump behind must be 1.5-2 times higher than that of the pump in front. In this way, we can perform our due effectiveness.
Overseas Roots vacuum pumps not only use the same type of two pumps with different capacities and sizes, but also often use different types of two pumps. They still make the capacity of the front suction pump small, the capacity of the back suction pump large, and they are designed as coaxial transmission, so that the coaxial compensation, the change range of the current of the two pumps is small, and the operation is convenient.
The use of series units should pay attention to the phenomenon of reverse flow of white water. When a series pump unit shuts down, there is often a lot of white water from the paper machine pouring into the pump cavity, especially the back suction pump of the unit. The suction port is below the pump body, and the water can not be swept away. Sometimes the water level is more than 250mm above the pump rotor. If self-consciously started under such conditions, the working medium of suction changed from air to water, and the motor would be overloaded and tripped. The treatment method is to install a one-way valve on the inlet pipeline to avoid white water flowing into the pump and to clean up the accumulated water at any time after shutdown.