Structure composition of roots pump

Structure composition of roots pump

How to arrange the two rotors of Roots vacuum pump in the pump body determines the overall structure of the pump. There are generally three schemes for the general structural arrangement of Roots vacuum pump at home and abroad

1. Vertical: the axes of the two rotors are installed horizontally, but the plane formed by the axes of the two rotors is perpendicular to the horizontal plane. In this structure, the intake and exhaust ports of the pump are set horizontally, and it is convenient to assemble and connect pipes. But its disadvantage is that the center of gravity of the pump is too high, and the stability is poor when running at high speed, so there are not many pumps with this structure type except for small size pumps.

2. Horizontal: the axes of the two rotors are installed horizontally, and the plane formed by the axes of the two rotors is in a horizontal direction. In this structure, the air inlet of the pump is above the pump, and the air outlet is below the pump (there are also opposite). The lower exhaust port is generally connected horizontally, so the intake and exhaust directions are perpendicular to each other. The exhaust port is connected with a three-way pipe, which opens in two directions. One end is connected with the exhaust pipe, and the other end is connected with the bypass valve. This structure is characterized by low center of gravity and good stability at high speed. This type of structure is widely used in large and medium pumps at home and abroad.

3. Vertical axis type: some foreign roots pump two rotor axis and the horizontal plane vertical installation. The assembly clearance of this structure is easy to control, the rotor assembly is convenient, and the floor area is small, but the gear and other transmission mechanisms are inconvenient to assemble and disassemble, and the lubrication device is also complex.

When the overall structure is determined, the structure and shape of the pump body will be determined accordingly.

4. Roots pump with overflow valve: in order to prevent accidents caused by overload, roots pump is equipped with a more reliable safety protector, that is, an overflow valve is installed on the bypass pipeline. When the exhaust port is at the specified pressure, the relief valve is closed. When the pressure of the vent exceeds the specified pressure, the valve of the relief valve will be automatically pushed open and overflow will occur. When the pressure of the vent becomes normal, the relief valve will automatically close again. It can be adjusted automatically, and it is also the allowable differential pressure device of the pump. Therefore, the biggest advantage of the relief valve is that the roots pump can operate continuously in various pressure ranges together with the front pump. With this design, the stopping time of the vacuum vessel in the rough vacuum state can be reduced by 30 ~ 50%. For larger pumps, the relief valve is installed in the bypass pipe outside the pump body. For smaller pumps, the relief valve is installed in the pump shell.

5. Roots pump with steam condenser: when it is necessary to pump steam, the air extraction unit must be designed with a condenser that can condense the steam. The condenser can be installed in front of the pump or behind the pump instead of on the pump body of roots pump. In some cases, condensing heat absorption can reduce the heating of roots pump. Assuming that the use of a duplex condenser, in the maintenance of the appropriate solvent can be used to remove dirt, steam can flow smoothly in the duct.