Speed regulation method of multistage centrifugal water pump for mine
At present, the common mining multi-stage centrifugal water pump speed control devices include hydraulic coupling speed control, liquid viscosity speed control clutch speed control and frequency conversion speed control motor.
Multi-stage centrifugal water pump for mine
1. The concept of three speed control methods for common mining multistage pumps
2. Liquid viscous transmission is a new technology. The liquid-viscous speed-regulating clutch uses viscous liquid as the working medium, and transmits power by the viscous shear force of the viscous liquid in the gap between the active and driven friction plates. Through the command current (mA) of the control system, the oil cylinder is pressurized to change the friction plate gap (that is, the oil film thickness), thereby changing the slip and torque of the active and driven friction plates to implement stepless speed regulation.
3. Changing the frequency of the input power at the stator end of the asynchronous motor, thereby changing the motor speed is called variable frequency speed regulation. There are three main types of frequency conversion devices for water pumps: AC-DC-AC-voltage, current and pulse width modulation (PWM).
Two. Which aspects of the pump speed control method should be referred to?
1. Price comparison. The hydraulic coupling is the most economical speed regulating device; the high-power variable frequency speed regulating motor and the speed regulating device are expensive.
2. Energy saving comparison. The fluid coupling is an additional slip speed regulating device, and its efficiency is the ratio of the output speed to the input speed, and the maximum speed can only reach 97%~98% of the input speed. The effect of energy saving is poor, especially at low speeds; the liquid viscous speed control clutch is also an additional poor speed control device, and its efficiency is also the ratio of the output speed to the input speed, but the liquid viscosity speed control clutch can be fully integrated, which can be 100% Ground transmission, which is better than the hydraulic coupling, the former has at least 3% speed difference; the variable frequency speed control motor is a speed control device without additional slip, and the efficiency is relatively high, especially at low speed, the effect is significant, but the frequency control The speed motor also has energy loss during the frequency conversion and voltage transformation process. The effect is significant when the speed is above 85%, but the frequency conversion speed regulation motor also has energy loss during the frequency conversion and voltage transformation process. When the speed is above 85%, its efficiency is not as good as the previous two The speed regulator is out.
3. Stability comparison. The impeller coupling is one of the most mature and reliable speed regulating devices. The speed is very reliable and stable in the speed range of 25% to 97%; the liquid viscous clutch is unstable in the range of 90% to 100%. If it is used If the speed is closed-loop control, oscillation will occur, which is not allowed; the variable frequency speed control motor can reliably adjust the speed in the range of 20% to 100%, but it is not as mature as the fluid coupling.
4. Maintenance comparison. The fluid coupling is a speed regulating device that is the easiest to maintain, and it is also the most familiar to maintenance personnel; followed by the liquid viscous clutch; the frequency conversion speed regulating motor has higher requirements for maintenance personnel.
