Application skills of screw pump in sewage treatment

Pumps are widely used in wastewater treatment plants to transport water, wet sludge and flocculant liquid because of their variable transportation, strong self-priming ability, reversibility and ability to transport liquid containing solid particles The selection of screw pump should follow the principle of economy, rationality and reliability If the design and selection are not considered carefully, it will bring trouble to the later use, management and maintenance Therefore, a reasonable and reliable screw pump selected according to the actual production needs can not only ensure the smooth production, but also reduce the repair cost Now we will introduce some experience in the application of screw pump as follows: first, the selection of rotating speed of screw pump The flow rate of the screw pump is linear with the rotating speed Compared with the low rotating speed screw pump, the high rotating speed screw pump can increase the flow rate and the head, but the power is obviously increased The high rotating speed speeds up the abrasion between the rotor and the stator, which will make the screw pump fail prematurely, and the length of the stator and rotor of the high rotating speed screw pump is very short, which is very easy to wear, so the service life of the screw pump is shortened Life Through reducer or stepless speed regulation mechanism to reduce the speed and keep the speed below 300 rpm, the service life can be extended several times compared with high-speed screw pump 2、 There are many kinds of screw pumps in the market Comparatively speaking, the imported screw pumps are of reasonable design and excellent materials, but the price is high, some services are not in place, the price of accessories is high, and the ordering period is long, which may affect the normal operation of production Most of the domestic products are imitated from the imported ones, and the quality of the products varies When choosing the domestic products, the products with low speed, long lead, excellent material of transmission parts and long rated life shall be selected when considering their cost performance 3、 Ensure that debris does not enter the pump body The solid sundries mixed in the wet sludge will damage the rubber stator of the screw pump, so it is very important to ensure that the sundries do not enter the cavity of the pump Many sewage plants have installed a crusher in front of the pump, and some have installed a grid device or filter screen to prevent the sundries from entering the screw pump The grid should be removed in time to avoid blocking 4、 Avoid breaking The screw pump is not allowed to operate under the condition of material breaking Once it happens, the rubber stator is burnt out due to dry friction and high temperature in an instant Therefore, the crusher is in good condition and the grid is smooth, which is one of the necessary conditions for the normal operation of the screw pump Therefore, some screw pumps also install the material breaking shutdown device on the pump body When the material breaking occurs, the screw pump has self-priming function The vacuum device will stop the screw pump 5、 The screw pump with constant outlet pressure is a positive displacement rotary pump When the outlet end is blocked, the pressure will gradually increase, so that it exceeds the predetermined pressure value At this time, the motor load increases sharply The load of the relevant parts of the transmission machinery will also exceed the design value In serious cases, the motor will burn out and the transmission parts will break In order to avoid damage to the screw pump, a bypass overflow valve is usually installed at the outlet of the screw pump to stabilize the outlet pressure and maintain the normal operation of the pump