The use of screw pump in sewage treatment

Screw pumps are widely used in the transportation of water, wet sludge and flocculant liquids in sewage treatment plants due to their characteristics of variable delivery, strong self-priming ability, reversibility, and the ability to transport liquids containing solid particles. . Screw pump selection should follow the principles of economy and reasonableness. If the design is poorly selected, it will cause troubles for future use, management, and maintenance. Therefore, using a practical and reliable screw pump in accordance with actual production needs can not only ensure smooth production, but also reduce repair costs.

First, the quality of the screw pump

There are many kinds of screw pumps on the market. Relatively speaking, the imported screw pumps are designed with reasonable materials and high quality. However, the prices are relatively high, some services are not in place, the accessories are expensive, and the long order period may affect the normal production. run.

Most of the domestic production of imitation of imported products, product quality varies greatly, in the selection of domestic production of products, when considering its cost-effective, choose low-speed, long lead, transmission components, material quality, long life rating of the product.

Second, the speed of the screw pump selection Screw pump flow and speed linear relationship, compared to low speed screw pump, high speed screw pump can increase the flow and head, but the power is significantly increased, the high speed speed up the rotor and Abrasive wear between the stators will definitely lead to premature failure of the screw pump, and the fixed rotor length of the high-speed rotary screw pump is very short and it is easy to wear, thus shortening the service life of the screw pump.

By reducing the speed through a speed-reducing mechanism or a stepless speed-regulating mechanism, the speed is maintained within a reasonable range below each minute of three hundred revolutions, and the service life can be extended several times as compared with a high-speed screw pump.

Third, to ensure that debris does not enter the pump wet sludge mixed with solid debris will damage the rubber pump stator stator, so to ensure that debris does not enter the pump cavity is very important, many sewage treatment plant in front of the pump The pulverizer is installed, and some grid devices or screens are installed to prevent debris from entering the screw pump. The grid should be cleaned in time to avoid clogging.

Fourth, to avoid the material screw pump must not be allowed to operate in the case of broken material, once it occurs, the rubber stator due to dry friction, instant high temperature and burn out, so the crusher is intact, smooth grille is necessary for the normal operation of the screw pump One of the conditions, for this reason, some screw pumps are also equipped with a shut-off stop device on the pump body. When the cut-off occurs, due to the self-priming function of the screw pump, a vacuum will be generated in the chamber and the vacuum device will stop the screw pump. Operation.

Fifth, to maintain a constant outlet pressure The screw pump is a positive displacement rotary pump, when the outlet end is blocked, the pressure will gradually increase, so that more than a predetermined pressure value. At this point, the motor load increases dramatically. The load of the related parts of the transmission machinery will also exceed the design value. In severe cases, the motor will be burned and the transmission parts will be broken. In order to avoid damage to the screw pump, a bypass relief valve is generally installed at the outlet of the screw pump to stabilize the outlet pressure and maintain the normal operation of the pump.

Overview of the screw pump: The screw pump is a single-screw type transport pump. Its main working parts are the screw (called the rotor) of the eccentric spiral body and the screw bush (called the stator) with the double-thread spiral surface on the inner surface. The working principle is that when the motor drives the pump shaft to rotate, the screw rotates around its own axis on the one hand and it rolls along the inner surface of the bush on the other hand, thus forming a sealed chamber of the pump. Every revolution of the screw, the liquid in the seal chamber is advanced by a pitch. With the continuous rotation of the screw, the liquid spirally presses from one seal chamber to the other, and finally the pump body is extruded. The screw pump is a new type of liquid conveying machine and has the advantages of simple structure, safe and reliable operation, convenient use and maintenance, continuous and uniform liquid discharging, stable pressure, and the like. The working principle of the screw pump is: when the screw pump is working, the liquid is sucked into the sealed space enclosed by the thread and the pump shell. When the active screw rotates, the screw pump sealing volume increases the screw pump pressure under the compression of the screw teeth. And move in the axial direction. Since the screw is rotating at a constant speed, the flow out of the liquid is also uniform.