Energy loss of horizontal multistage centrifugal pump
There are three energy losses in the flow of actual liquid from the pump population to the pump outlet. These energy losses reduce the efficiency of the centrifugal pump.
Mine wear-resistant multistage pump
1. Hydraulic loss
Surface friction occurs when liquid flows through the contacted channels, and the resulting energy loss depends primarily on the length, size, shape, surface roughness, and flow rate characteristics of the liquid. It includes the impact loss caused by the liquid flow in the human leaf channel and the pressure chamber flow path, the frictional resistance loss along the liquid flowing through the liquid absorption chamber and the diffuser tube, and the liquid flowing through the above-mentioned places due to turning and contraction or expansion, etc. The resulting vortex loss.
2. The volume loss
The loss due to the leakage of the seal gap is called volume loss. The volume loss includes leakage loss of the seal ring, leakage loss of the balance mechanism, loss between stages, and loss of the loss of the packing. In order to reduce the volume loss, the sealing gap should be minimized and the wear resistance and assembly precision of the seal should be improved.
3. Seal ring leakage loss
When the pump is working, there is always a pressure difference between the two sides of the seal ring, so there will always be a part of the liquid from the impeller outlet to the leaf: the wheel population leaks. The energy of the leaking liquid is all used to overcome the resistance of the seal ring.
4. Balance mechanism leakage loss
In many vertical multistage pumps, there are mechanisms for balancing axial thrust, such as balance holes, balance tubes, balance plates, and the like. Since there is a pressure difference on both sides of the balance mechanism, a part of the liquid leaks from the high pressure region to the low pressure region.
5. Leakage loss between stages
In the volute multi-stage pump, the pressure on both sides of the stage spacer is not equal, and thus there is also leakage loss.
6. Mechanical loss
Mechanical losses include frictional losses between the pump shaft and the bearings and seals, and frictional losses (wheel resistance losses) between the outer surface of the impeller front and rear covers and the liquid. Mechanical losses are independent of flow.
Normal starting conditions for horizontal multistage centrifugal pumps
1 The steering of the motor should be the same as the steering indicated by the pump (reverse flow and head are significantly reduced);
2 The fixed connection parts should be free from looseness, and the lubrication parts should be filled with lubricant to prevent dry rotation;
3 The parts with pre-lubrication requirements shall be pre-lubricated as required;
4 All indicating instruments and safety protection devices should be sensitive, accurate and reliable;
5 cars should be flexible, no abnormalities;
Horizontal multistage pump operation precautions
1 It is forbidden to run without water, do not adjust the population to reduce the displacement, and prohibit running under too low flow rate;
2 to ensure that the mechanical seal has a fully flushed water flow, water-cooled bearings are prohibited from using excessive water flow;
3 Do not use too much lubricant;
4 Check according to the recommended cycle. Establish operational records, including hours of operation, adjustment and replacement of mechanical seals, addition of lubricants and other maintenance measures and time. Pumping and discharge pressures, flow rates, input power, wash and bearing temperatures, and vibration conditions should be measured periodically.
5 Centrifugal pump relies on atmospheric pressure to pump low water to a high point, while atmospheric pressure can only support water column of about 10.3m at most, so theoretically all the main engine of the pump can not get water from the water surface 10.3 meters, according to the actual situation The air pressure and sealing performance are generally not more than 6 meters, and the measures such as vacuum pump can reach about 7.5, and the self-priming water supply time can be effectively reduced.
