The twin-screw pump is very similar to the gear pump. One screw rotates to drive the other screw. The liquid is intercepted in the meshing chamber, pushed along the rod axis, and then squeezed to the center to be discharged.
1) Wide range of pressure and flow;
2) Wide range of types and viscosities of liquids to be transported;
3) Because the inertial force of the rotating parts in the pump is low, a high speed can be used;
4) Good suction performance and self-priming ability;
5) The flow is uniform and continuous, with little vibration and low noise;
6) Compared with other rotary pumps, it is less sensitive to incoming gas and dirt;
7) Solid structure, easy installation and maintenance.
The processing and assembly requirements of the screw are high; the performance of the pump is sensitive to changes in the viscosity of the liquid.
When the piston moves to the right, the pressure in the cavity decreases, the upper valve is pressed down, the lower valve is pushed up, and the liquid is sucked in; when the piston moves to the left, the pressure in the cavity increases, the upper valve is pushed up, the lower valve is pushed down, and the liquid is discharged.
(1) High discharge pressure can be obtained, and the flow rate has nothing to do with the pressure, the suction performance is good, and the efficiency is high, among which the steam reciprocating pump can reach 80%~95%;
(2) In principle, any medium can be transported, almost not limited by the physical or chemical properties of the medium;
(3) The performance of the pump does not change with the change of the pressure and the viscosity of the conveying medium.
Other pumps do not have the above outstanding advantages of reciprocating pumps, but their structure is relatively simple, the use and operation are relatively convenient, and they also have the advantages of small size, light weight, uniform flow, and serialized mass production.
Traffic is not very stable. Under the same flow rate, it is larger than the centrifugal pump; the mechanism is complex; the capital consumption is large; it is not easy to maintain, etc.
Compared with the reciprocating pump, the screw pump has the following characteristics:
1. It has a simple structure. The total number of parts is 55% of the reciprocating pump with the same working parameters, and the total number of wearing parts is 17% of the reciprocating pump.
2. The screw pump is small in size and light in weight. The weight is 20% of the reciprocating pump with the same working parameters.
3. The flow is uniform, the pressure is stable, and there is no pulsation.
4. The cost is low, which is 30% of the reciprocating pump with the same working parameters.
5. The manufacturing process of the screw pair of the screw pump bushing is complicated and the service life is low.
6. It is difficult to start, and the efficiency is low (the efficiency is 50-70%).
The screw pump can be used to transport clean water, mud, chemical slurry, oil, etc.
The screw pump is divided into a single-wave tooth screw pump and a multi-wave tooth screw pump according to the number of waves of the screw (or the number of threads).