Selection and application of screw pump

Screw pumps are widely used in sewage treatment plants to transport water, wet sludge and flocculant liquids due to their variable volume transport, strong self-priming ability, reversibility, and ability to transport liquids containing solid particles. . The selection of screw pump should follow the principles of economy, reasonableness and reliability. If the design and selection are not considered carefully, it will cause trouble in future use, management, and maintenance. Therefore, choosing a reasonable and reliable screw pump based on actual production needs can not only ensure smooth production, but also reduce repair costs.

screw pump
screw pump
  1. Selection of screw pump speed

The flow rate of the screw pump has a linear relationship with the rotation speed. Compared with the screw pump with a low rotation speed, the screw pump with a high rotation speed can increase the flow rate and lift, but the power is significantly increased. The high rotation speed accelerates the wear between the rotor and the stator, which will inevitably cause The screw pump fails prematurely, and the stator and rotor of the high-speed screw pump are very short and easy to wear, thus shortening the service life of the screw pump.

The speed is reduced through a deceleration mechanism or a stepless speed regulating mechanism to keep the speed within a reasonable range of less than 300 rpm. Compared with a high-speed screw pump, the service life can be extended several times.

  1. Quality of screw pump

There are many types of screw pumps. Relatively speaking, imported screw pumps have reasonable designs and excellent materials, but they are more expensive, some services are not in place, the accessories are expensive, and the ordering cycle is long, which may affect the normal operation of production.

Most of the domestically produced products are imitations of imported products, and the quality of the products varies. When selecting domestically produced products, when considering their cost performance, choose products with low speed, long lead, excellent materials for transmission components, and long rated life.

  1. Ensure that debris does not enter the screw pump

The solid debris mixed in the wet sludge will cause damage to the rubber stator of the screw pump, so it is very important to ensure that debris does not enter the pump cavity. Many sewage plants have installed crushers in front of the pumps, and some have installed The grille device or filter prevents debris from entering the screw pump. The grille should be cleared in time to avoid clogging.

  1. Avoid screw pump outage

The screw pump is never allowed to operate when the material is cut off. Once this occurs, the rubber stator will instantly generate high temperature and burn out due to dry friction. Therefore, the pulverizer is intact and the grille is unobstructed. This is one of the necessary conditions for the normal operation of the screw pump. In addition, some screw pumps are also equipped with a material interruption and shutdown device on the pump body. When a material interruption occurs, due to the self-priming function of the screw pump, a vacuum will be generated in the cavity, and the vacuum device will stop the screw pump.

  1. Maintain constant outlet pressure of screw pump

The screw pump is a positive displacement rotary pump. When the outlet end is blocked, the pressure will gradually increase to exceed a predetermined pressure value. At this time, the motor load increases sharply. The load on the relevant parts of the transmission machinery will also exceed the design value. In severe cases, the motor will burn out and the transmission parts will break. In order to avoid damage to the screw pump, an oil return valve is generally installed at the outlet of the screw pump to stabilize the outlet pressure and maintain the normal operation of the pump.

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