How can self-priming chemical pumps be used to save energy?
1 Improve the water pump maintenance process to reduce hydraulic loss
1.1 Improve the flow path finish
During the inspection, the rust, scale, burr and flash of the impeller and the flow passage of the blade are polished and polished, so that the smoothness of the flow channel reaches Δ4 or more, and the friction between the water and the flow wall is reduced to impact the vortex loss. However, due to the limitations of the site conditions, it is not easy to polish the entire flow-passing part. It is important to polish and polish the key parts that affect the efficiency, such as the positive guide vane, the inlet of the impeller, and the exit of the impeller. Wait. It is only necessary to polish the metallic luster, and the original profile of the flow channel must not be destroyed.
1.2 Improve the smoothness of the outer wall of the impeller and the inner wall of the pump casing. During the inspection and repair, the embroidering scale and burr of the outer wall of the impeller and the inner wall of the pump casing are polished and polished, while keeping the scoring deviation of the impeller not exceeding the specified value, reducing the friction loss of the disc.
1.3 Reduce the impact loss of the impeller outlet
When the impeller and vane circulation center are coping, the impeller flow passage cannot exceed the vane flow passage, and the impeller outlet should not have burrs or flash edges. When installing, the axial dimension of the rotor and the pump casing should be controlled within the allowable range. The axial displacement change of the pump reflects the difference between the impeller and the vane of each stage. The axial displacement of the pump should be controlled during normal operation. To reduce the impact loss of the impeller outlet fluid.
2 Reduce volume loss and improve operating efficiency
(1) Reduce the leakage loss in the pump, improve the machining accuracy and assembly quality of the parts, reduce the radial clearance of the front disc of the balance disc and the radial clearance of the front and rear seal rings and the vane seal ring, and reduce the liquid in the pump. The pressure loss caused by leakage on the high pressure side to the low pressure side. For the impeller seal ring, the guide vane sleeve, the balance plate front throttle and other components, the material with higher hardness should be selected, and the heat treatment for improving the wear resistance should be performed.
(2) When starting the feed pump in cold state, the pump should be fully warmed according to the requirements of the regulations. If the warm pump is not sufficient, the pump body will easily generate a large thermal temperature difference, which will cause the bow to deform. At this time, the pump is easy to make the internal seal gap. Grinding, resulting in internal leakage and increased backflow volume loss.
(3) Carefully monitor the axial turbulence of the pump and the change of the discharge pressure after the balance disc during operation. During normal operation, the pressure after the balance disc is larger than the inlet pressure of the pump, and should be repaired in time to reduce leakage. Loss and increase the volumetric efficiency of the pump.
(4) When adjusting the load, it should be stable, avoid the large fluctuation of the water supply pressure, maintain the continuous and stable operation of the feed water pump, and reduce the axial movement of the pump to avoid the wear of the seal gap.
3 Reduce the leakage loss of the water supply system
(1) Under normal operating conditions, the water discharge door, the drain door, the pump drain valve, the boiler's regular drain door, and the accident drain door of the water supply system should be closed tightly, and the hand should be cool after the door is inspected. If the valve is not strict, it should be processed in time.
(2) Reduce the leakage loss of the feed pump recirculation door. The feed water pump recirculation device is used to maintain a minimum flow rate when the feed water pump is started, when it is put into operation, and when the boiler water supply is stopped, so as to prevent heat from being generated due to small flow during operation, and the water is vaporized, causing an accident. The recirculation door should be closed tightly during normal operation. At the scene, due to problems such as structure and material, the recirculation door is generally leaked under the action of large pressure difference, and a large amount of high-pressure feed water is returned to the deaerator for useless work, resulting in waste of electric energy and even affecting boiler feed water. At this point, the operation should be withdrawn in time to repair the leaking door with serious leakage and maintain its good tightness. In addition, when starting the feed pump, when the pump is running normally, the recirculation door should be closed in time to reduce the power loss at this time.
(3) The exit gate of the standby feed pump should be strict, and the outlet valve of the feed pump that is connected to the standby is generally open. If the back door is not strict, the high pressure feed water leaks back to the deaerator through the pump body, and even causes the backup pump to reverse. It should immediately exit the standby for treatment, which not only reduces the pressure energy loss of the high pressure feed water, but also ensures the safe standby of the equipment. In addition, in the case of meeting the water supply needs, only the "feedwater pump outlet door" can be kept in the fully open state, and the exit valves of other standby pumps can be closed to reduce the leakage loss.
4 application of inverter controller
The water pump frequency conversion speed regulation operation means that the water pump is driven by the adjustable speed motor, and the operating condition of the water pump device is changed by changing the rotation speed. This greatly expands the effective working range of the pump and is a very important and applicable adjustment method in engineering. At present, the electric energy consumed by the motor accounts for about 65% of the industrial power consumption. The motor used in most equipment is still a general non-regulating motor. If these non-regulating motors are converted into speed-regulating motors, and their power consumption varies with load, a large amount of electric energy can be saved. According to the centrifugal pump principle, in a similar situation, the flow, head and power of the pump are proportional to the primary, secondary and cubic of the rotational speed. For the occasion where the water often changes, the water supply with variable frequency speed control pump can significantly reduce the throttling loss and has obvious energy saving effect.
Compared with other speed control technologies, the water pump frequency conversion speed control technology has the following advantages: First, the speed control efficiency is high. The frequency conversion speed regulation is that after the frequency changes, the motor still runs near the synchronous speed of the frequency, basically maintains the rated speed difference, and the speed loss does not increase. Therefore, the variable frequency speed control water pump is a high efficiency speed control pump. Second, the speed range is large. The speed range of the inverter can reach 1%-100%, and it has high speed regulation efficiency in the whole speed regulation range. When the speed regulation range is less than 30%, the inverter efficiency can reach 90%. Therefore, the variable frequency speed control water pump is especially suitable for a state in which the speed regulation range is wide and is often operated under a low load state. Third, the speed regulation is convenient. It is necessary to adjust the speed of the original motor without having to replace the motor. Fourth, continuous speed regulation is possible, and the starting current is small. Choose a better running speed, which can achieve low speed start and smooth speed control. The maximum speed is not affected by the power supply, and the motor can be speeded up and miniaturized. Fifth, the frequency conversion device can double as a starting device. The motor is started to a certain speed through the variable frequency power supply, and then the variable frequency power supply is disconnected, and the motor is accelerated to full speed by the commercial frequency power supply. Sixth, the main circuit can maintain direct power supply. When the inverter device fails, it can be taken out of operation, and the main circuit is directly powered, which does not affect the continued operation of the pump.