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Oil vacuum pump maintenance and maintenance

Oil vacuum pump maintenance and maintenance

The quality of the vacuum pump depends on its mechanical structure and the quality of the oil. It must be well protected when using the vacuum pump. If the volatile organic solvent is distilled, the organic solvent will be absorbed by the oil, which will increase the vapor pressure, thereby reducing the evacuation efficiency. The turbid liquid is pumped out and the vacuum pump is damaged.
Therefore, the following points must be paid attention to when using the vacuum pump:
Between the distillation system and the vacuum pump, an absorption device must be installed.
Before distillation, the vapor of organic solvent in the system must be completely evacuated with a water pump.
If a pump can be used to pump air, use a pump as much as possible. If the distillate contains volatile substances, the pump can be used to reduce the pressure and then use an oil pump.
The decompression system must be kept airtight, all rubber stoppers should be of suitable size and holes, and the rubber tube should be a rubber tube for vacuum. Ground glass coated with vacuum grease.

Vacuum pumps can be divided into three categories according to the scope of use and pumping efficiency:
(1) For general water pumps, the pressure can reach 1.333~100kPa (10~760mmHg) as a "coarse" vacuum.
(2) Oil pump, the pressure can reach 0.133~133.3Pa (0.001~1mmHg), which is the "second highest" vacuum.
(3) Diffusion pump, the pressure can reach below 0.133Pa, (10-3mmHg) is "high" vacuum.
If you want a lower pressure, you need to use an oil pump. A good oil pump can pump below 133.3Pa (1mmHg).
There are two types of decompression pumps commonly used in organic chemistry laboratories: water pumps and vacuum pumps. If very low pressure is not required, a water pump can be used. If the water pump is well constructed and the water pressure is high, the evacuation efficiency can reach 1067~3333Pa (8 ~25mmHg). The lowest pressure that the pump can pump is theoretically equivalent to the water vapor pressure at the water temperature at that time. For example, when the water temperature is 25°C, 20°C, and 10°C, the pressure of the water vapor is 3192, 2394, and 1197Pa (8-25mmHg), respectively. When pumping air with the water pump, a safety bottle should be installed in front of the water pump to prevent the water pressure from dropping and the water flow sucking back; before stopping the air pumping, the air should be released first, and then the water pump should be turned off.
high motor temperature
A company's 300MW unit, each unit is equipped with 2 mechanical vacuum pumps, one of which is running and one is standby. The vacuum pump is used to evacuate the unit when it starts, and it is used to pump out the uncondensed gas in the condenser during normal operation. The pump is equipped with a motor of 160kW, a speed of 590r/min, a rated current of 330A, a voltage of 380V, class B insulation, and a current of 220 to 230A during normal operation. Every summer, the temperature of the motor will exceed the limit, and it is forced to install a temporary cooling fan, but the effect is not great. Long-term high temperature operation of the motor will cause insulation aging and shorten its service life. The reasons for the high temperature of the vacuum pump motor are analyzed as follows.

Cause Analysis
(1) The motor power is large, the working current is large, and the calorific value is large.
(2) The fan speed is low, the wind pressure and the air volume are small.
(3) The number of fan blades is small, and the air volume generated is small.
(4) The motor is attached with dust and oil, which reduces the heat dissipation capacity.
(5) The voltage of the busbar where the vacuum pump motor is located is 380V. Due to the cable voltage drop and uneven load distribution, the actual voltage applied to the motor is only 365V, and the low voltage causes a large operating current.
The motor power and speed are matched with the vacuum pump and cannot be changed. The fan is installed on the main shaft of the motor, and the speed of the motor determines the speed of the fan, and it cannot be replaced. Although increasing the number of fan blades can play a certain role, after the number of blades increases, the dynamic balance is not easy to find. If the alignment is not good, the vibration of the motor will increase.
(1) Lengthen the original fan cover by 40cm, and install an axial flow fan with the same diameter as the fan cover. The motor power of the axial flow fan is 850W, the speed is 1489r/min, and the voltage is 380V. The original fan remains. The axial flow fan is provided with another power supply control, and the axial flow fan is not interlocked with the main motor. Start the axial flow fan in time after the vacuum pump is started, and stop the axial flow fan 30 minutes after the vacuum pump is stopped, so that the main motor can be fully cooled;
(2) Regularly remove dust on the motor, keep the motor heat sink clean, and increase its heat dissipation capacity;
(3) Adjust the bus voltage of the vacuum pump to 400V.

(1) Due to the high rotational speed of the axial flow fan and the large air pressure and air volume, the cooling effect is greatly enhanced. Under the same ambient temperature and load current, the temperature of the main motor drops by 12 °C. The temperature of the main motor does not exceed the limit in summer.
(2) The axial flow fan can be controlled manually. After the main motor is stopped, the axial flow fan can still run, which can fully cool the main motor.
(3) Try to balance the load distribution of the 2-section busbars to prevent excessive voltage drop in a certain section of busbars due to heavy load.
(4) After the voltage is adjusted, the operating current of the vacuum pump is reduced to 210A, and the calorific value is relatively reduced.
(5) Slow down the insulation aging speed of the main motor and prolong its service life.
Pump shaft bearing wear
Wear of vacuum pump transmission parts is a common problem, including bearing positions, bearing seats, bearing chambers, keyways and threads. The traditional methods are mainly repair welding and brush plating, but both have certain drawbacks: repair welding high temperature The generated thermal stress cannot be completely eliminated, and it is easy to cause material damage, resulting in bending or breaking of parts; while brush plating is limited by the thickness of the coating, it is easy to peel off, and the above two methods are to repair the metal with metal, which cannot change the "hard pair". The "hard" cooperation relationship will still cause re-wear under the combined action of various forces. Contemporary western countries mostly use the repair method of polymer composite materials to solve the above problems, and the most widely used is the American Meijiahua technology system, which has comprehensive properties such as super adhesion and excellent compressive strength. It is repaired by polymer materials, which can be disassembled and machine-free. It is not affected by the thermal stress of repair welding, and the repair thickness is not limited. At the same time, the metal material of the product does not have the concessional property, which can absorb the shock and vibration of the equipment, avoid the possibility of re-wear, and greatly prolong the service life of the equipment parts. Businesses save a lot of downtime and create enormous economic value.
Corrosion Polymer Composites Repair Vacuum Pump Corrosion
The form of vacuum pump corrosion can be divided into two categories: comprehensive (uniform) corrosion and localized corrosion. The former occurs more uniformly on the entire surface of the vacuum pump, while the latter only occurs locally, such as pitting corrosion, crevice corrosion, intergranular corrosion, stress corrosion, etc. . The use of polymer composite materials to implement anti-corrosion on the surface of vacuum pumps with organic coatings has good chemical resistance and excellent mechanical properties and adhesion properties. Compared with traditional pressure vessel welding and repairing, it has the advantages of simple construction, low cost and safety performance. , the repair effect is good.
Shell cracks and cracks repairing shell cracks with polymer composites
Vacuum pumps often cause cracks or fractures in parts due to casting, machining defects, internal stress and overload operation. The conventional repair method is to use welding, but some parts are made of cast iron, aluminum alloy, and titanium alloy, which are difficult to be welded. There are also some dangerous occasions that are prone to explosion, and it is even more difficult to use welding repair methods. Meijiahua technology is a "cold welding" technology, which can avoid thermal stress deformation. At the same time, the material has good adhesion, compression resistance, corrosion resistance and other comprehensive properties, which can meet the requirements of various equipment components to the greatest extent, so that the lowest Effectively guarantee production under cost input. Safe, convenient and reliable.

smoke and fuel injection
1. Smoke, if the pump has just started to run and there is smoke, it is normal, if it is smoking for a long time, it is not normal. Solution: The smoke indicates that the air inlet of the pump, including the pipes, valves, and containers, has been repaired. After the leak detection is processed, the smoking will end. Vortex flowmeter
2. Fuel injection means that there are a lot of leakage points outside the air intake, and even the air intake is exposed to the atmosphere. Solution: seal the air inlet of the pump to make the pump run, if it does not inject fuel, it means there is a leak; the exhaust valve is damaged, check whether the exhaust valve is damaged, and replace the bad exhaust valve.

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