Pump types are very many, here we introduce the most basic "centrifugal pump", its structure is as follows:
Working principle is: the liquid rotates with the impeller and moves to the outer edge along the channel between the blades under the action of centrifugal force. The speed increases and the mechanical energy increases. Liquid leaves the impeller and enters the volute, flow channel of the volute expands gradually, fluid speed slows down, the liquid kinetic energy is converted into static pressure energy, and the pressure keeps rising, and finally flows out of the volute along the tangential direction and is discharged through the catheter:
Animation of the working process is as follows:
Impeller
Impeller transfers the mechanical energy of the prime mover to the liquid. Core components that enhance liquid energy. It has three types of open, semi-open and closed impeller:
Open impeller without front and back plate and only blade, mostly used for conveying liquid containing impurities, such as submersible pump impeller is the use of open impeller.
The semi-open impeller only has rear disk.
Closed impeller has both front plate and back plate, the impeller of the clean water pump is closed impeller.
Impeller should have enough strength and steel, flow channel shape in line with the flow law of liquid, flow channel surface roughness is small; The material should have good wear resistance; Simple structure, good manufacturing technology. The impeller of the centrifugal pump is generally a backward blade, through casting.
If the transfer fluid viscosity is high, motor speed can't be 2900 RPM. There should be have gear motor or pulley between the motor and the pump to reduce pump speed. In this way, high viscosity liquids can be transferred.
Pump case
Pump shell collects the liquid from the impeller, and converts the kinetic energy of part of the liquid into pressure energy, and finally leads the liquid evenly to the secondary impeller or the guide outlet.
Casing of single-stage centrifugal pump is mostly spiral spiral shell, which has the characteristics of convenient manufacturing and high efficiency. The output of the cochlear machine should be in the same direction as the rotation of the impeller:
Stuffing box
Stuffing box is mainly used to prevent the leakage of the liquid when the pressure increases. There are many types of sealing devices, the most used is the packing seal and mechanical seal.
Packing seal is some soft packing with a certain pressure on the shaft to achieve the purpose of sealing. Soft packing is oil-soaked or graphite coated asbestos rope, put it between the stuffing box and the pump shaft, pressing the gland to make it deformation to seal. Fillers are damaged after a period of use and require regular inspection and replacement.
Mechanical seals have two hard and smooth surfaces, one static and one rotating. This sealing device can achieve good sealing requirements, but should not be used in the delivery system containing impurities, because the smooth surface will be broken and lose sealing effect. This type of seal is very common in liquid circulation systems:
The above is the main content of the centrifugal pump structure.
