Preparatory Work Before Centrifugal Pump Starts
A. centrifugal pump before startup inspection
The name, type, main performance and quantity of lubricant are in line with the requirements of technical documents.
Whether the bearing lubrication system, sealing system and cooling system are in good condition, and whether the bearing oil and water lines are unblocked;
The rotor of the disc pump is rotate 1~2 times to check whether the rotor is rubbed or jammed.
Is there any debris that prevents rotation in the vicinity of the coupling or belt protection device?
Whether the foundation bolts of pump, bearing block and motor are loose;
The valve or accessories of the pump working system should be in the position of the minimum load when the pump is running, and the outlet regulating valve should be closed.
Point pump, to see whether the impeller steering is consistent with the design steering, if not consistent, it is necessary to make the impeller completely stop rotation, adjust the motor wiring, before restarting.
B. centrifugal pump water filling
Before starting the pump, the pump shell and the suction pipe must be filled with water. This is because in the presence of air, the pump suction port vacuum can not be formed and maintained.
C. centrifugal pump warm pump
The multistage centrifugal pumps that deliver high temperature liquids, such as boiler feed pumps of power plants, must be warm before starting. This is because when the feedwater pump starts up, the high temperature feed water flows through the pump, so that the temperature of the pump body rises rapidly from room temperature to 100-200 degrees centigrade, which will cause the temperature difference between the inside and outside of the pump and between the parts. If there is not enough long time for heat transfer and proper measures to control the temperature rise, the expansion of the pump will be uneven, resulting in the deformation and grinding of the parts of the pump body. Damage, vibration and bearing axle holding accidents.
Two, matters needing attention
Centrifugal pump is a vane pump, relying on the rotating impeller in the rotating process, due to the interaction between the blade and the liquid, the blade will transfer mechanical energy to the liquid, so that the pressure of the liquid can be increased, to achieve the purpose of transporting liquid. Four points should be paid attention to when starting a centrifugal pump.
(1) the centrifugal pump has a limited value at a certain speed. The flow rate and shaft power at the operating point depend on the condition of the device system connected to the pump (position difference, pressure difference and pipeline loss). The lift varies with the flow rate.
2. Stable operation, continuous conveying, no pulse flow and pressure.
Generally, there is no self sucking ability. It is necessary to fill the liquid first or pump the pipeline into vacuum before it can start work.
(4) The centrifugal pump starts when the discharge pipeline valve is closed, and the vortex pump and the axial flow pump start when the valve is fully open to reduce the starting power.
Because the centrifugal pump relies on centrifugal impeller force to form a vacuum suction to lift water, so when the centrifugal pump starts, must first close the gate valve, irrigation. The water level exceeds the impeller position and the air in the centrifugal pump can be discharged to start. After starting, a vacuum is formed around the impeller to suck up the water, and the gate valve can be automatically opened to lift the water. Therefore, we must first close the gate valve.
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