Screw pump classification and performance screw pump according to the number is divided into. This article Keywords: screw pump
Single Screw Pump - A single screw engages a rotating pump in the internal thread groove of the pump body.
Twin Screw Pump - A pump that pumps liquid between two screws.
Multi-Screw Pump - A pump that pumps liquids by engaging multiple screws.
Single screw pump is a single screw pump, its main working parts are eccentric screw spiral (referred to as the rotor) and the inner surface of the double helical screw bush (called stator). Its working principle is that when the motor drives the pump shaft to rotate, the screw rotates on its own axis on the one hand, and on the other hand, it rolls along the inner surface of the liner to form a sealed chamber of the pump. Each revolution of the screw, the liquid in the sealed cavity is pushed forward by one pitch. As the screw rotates continuously, the liquid spirally presses from one sealed cavity to the other sealed cavity, and finally the pump body is extruded. Screw pump is a new type of liquid conveying machinery, with the advantages of simple structure, safe and reliable operation, convenient use and maintenance, continuous and uniform liquid discharge, and stable pressure.
A pump that uses the rotation of a screw to pump liquid, which is best suited for absorbing viscous liquids.
The basic working principle of the screw pump 1. The working principle of the screw pump is: screw pump work, the liquid is sucked into the screw and the pump casing into the enclosed space, when the active screw rotation, the screw pump seal volume in the screw teeth Squeeze to raise the screw pump pressure and move in the axial direction. Since the screw is rotating at a constant speed, the flow of liquid out is also uniform.
Screw pump features: screw pump loss, good economic performance. High pressure and uniform, uniform flow, high speed, with the original direct motivation.
Screw pump can transport lubricating oil, conveying fuel, conveying a variety of oils and polymers for conveying viscous liquid.
High viscosity medium transport: Screw pump is the use of screw rotation to suction and discharge liquid. The screw is an active screw driven by the prime mover. The screw on both sides is a driven screw, which rotates reversely with the active screw. Active screw driven screw thread are double-headed thread.
Due to the mutual engagement of the screws and the tight fit of the screw with the inner wall of the liner, one or more sealed spaces are separated between the suction and discharge of the pump. As the screw is rotated and engaged, these sealed spaces are constantly formed at the suction side of the pump, the liquid in the suction chamber is enclosed therein and continuously displaced in the axial direction of the screw from the suction chamber to the discharge end, to be enclosed in the spaces Continued discharge of liquid, like a nut in the screw rotation is constantly moving forward, as the case, which is the basic working principle of screw pump.
2. According to the size of the pump can deliver viscosities from 37000-200000 centipoise medium.
Medium containing particles or fibers: The particle diameter can be 30mm (not exceeding rotor eccentricity). The fiber length can be 350mm (equivalent to the pitch of 0.4 rotor). Its content is generally up to 40% of the media pit, the medium if the solid matter is a fine powder, the maximum content of up to 60% or more can also be transported.
Requires delivery pressure is stable, the media do not like to destroy the inherent structure, the selection of single screw pump ideal delivery.
Screw pump often encounter problems 1. Pump vibration or noise:
Causes: Pump installation is not strong or the pump is installed too high; Motor ball bearings damaged; Pump spindle bending or not with the motor spindle, not parallel and so on.
Treatment: install a steady pump or reduce the installation height of the pump; replace the motor ball bearings; correct the bending of the pump shaft or adjust the relative position of the pump and the motor.
2. Drive shaft or motor bearing overheat:
Reason: lack of oil or bearing rupture.
Approach: add oil or replace the bearing.
3. Pump does not water:
Reason: pump and suction pipe did not fill the diversion; moving water level lower than the pump drainage pipe; suction pipe rupture.
The sealing surface between the screw and the housing is a curved surface. There are unsealed areas such as ab or de on this surface and a number of triangular notches abc, def with the groove portion of the screw. The notches of these triangles form a passage for the liquid, allowing the drive screw groove A to communicate with the grooves B, C in the driven screw. The grooves B, C, along with their spiral around the back, respectively, and the back of the grooves D, E communicated. Since there is also a triangular notch a "" b "" c "" similar to the front surface on the sealing surface where the grooves D, E engage with the groove F (which belongs to the other thread), D, F, E will also be connected. In this way, the groove ABCDEA also form a ∞-shaped sealing space (such as the use of single-head thread, the groove will be along the axial disc Rao screw, the suction port through, can not form a seal). Not hard to imagine, in such a screw, will form a number of independent ∞-shaped seal space, seal space occupied by each axial length just equal to the lead t of the tired rod. Therefore, in order to make the suction and discharge of the screw, the length of the screw thread should be longer than one lead.
Screw pump advantages From the above work can be seen, screw pump has the following advantages:
1) Wide range of pressure and flow. The pressure is about 3.4-340 kgf / cm 2, the flow rate is up to 18,600 cm 3 / min;
2) Wide range of liquid types and viscosities;
3) Because of the lower inertial force of rotating components in the pump, it can use high speed;
4) Inhalation performance, self-priming capability;
5) uniform and continuous flow, small vibration, low noise;
6) less sensitive to incoming gas and dirt compared to other rotary pumps;
7) solid structure, easy installation and maintenance.
The disadvantage of the screw pump is that the screw machining and assembly requirements are higher; the performance of the pump is sensitive to changes in the viscosity of the liquid.
Screw pump management 1) Start screw pump should stop suction valve in full open case to prevent overload or suction air.
Although the pump has dry suction capacity, but must prevent dry rotation, so as not to scratch the work surface.
If the pump needs to be started with very low oil temperature or high viscosity, it should be started with the suction valve and by-pass valve fully open to minimize the load when starting the pump. Until the prime mover reaches the rated speed, Bypass valve gradually closed.
When the by-pass valve is opened, the liquid is circulated and circulated in the pump under the condition of throttling, and the more the circulating oil is, the longer the circulating time is, the more severe the heat of the liquid is, and even the pump factor High temperature deformation and damage, we must pay attention.
2) Screw pump operation must be the direction of the established operation, to produce a certain suction row.
Pump work, should pay attention to check the pressure, temperature and mechanical seal work. Shaft seal should allow a trace of leakage, such as leakage does not exceed 20-30 seconds / drop, then that normal. If the pump is noisy at work, it is often caused by too low an oil temperature, too high a viscosity of the fluid, air entering the fluid, loss of coupling, or excessive wear on the pump.
3) Stop the pump, stop discharging the stop valve, and close the suction stop valve after the pump stops completely.
4) Screw pump due to the larger working screw length, poor rigidity, easily lead to bending, resulting in abnormal work. Shaft connection must be well centered; the best work is to be carried out after the installation of positioning, so as not to cause deformation of the pipeline implicated; connection pipe should be independently fixed, as far as possible to reduce the implication of the pump. In addition, the spare screw, the best preserved in the use of suspended fixed method to avoid distortion caused by uneven placement of the third century BC, Archimedes invented the spiral rod, the water can be smooth and continuous to a few meters high , The principle is still used by modern screw pump.