On variable-frequency control of water pumps
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Dear sea friends, please share your insights: I have a 15-ton steam boiler in operation here, equipped with a DG25-30x7 30KW pump, manufactured by Shanghai Kaiquan. By utilizing the remote signal from the magnetic flap level gauge, a control signal is generated via the PLC to drive the frequency converter, which in turn controls the water pump. Due to the very low production load at the factory at present, the backup pump operates at a low frequency, around 25HZ; sometimes it even stops running. After contacting the pump manufacturer, they advised against using variable-frequency control for this type of DG pump, suggesting instead that it operate at a fixed frequency of 45HZ, as otherwise it could damage the balance disk and shorten its service life. What do you all think? Is there a better way to supply water?
A pump with a lower power rating can be used; the small pump runs continuously under light loads, while the large pump starts automatically under heavy loads, and it stops again once the load decreases.
The bypass valve is used for adjustment, allowing excess water to return to the water tank. A 15-ton steam boiler definitely has a water softening tank at the beginning; a bypass is used to send excess water back to the tank, thus creating a circulation system.
Your insights are valuable; I still have the following questions: 1- Does the bypass valve need to be electric? Should we simply use a small tube as a loop? 2- Can the DG-type horizontal boiler feed water pump be used with frequency conversion at high frequencies?
Doing this doesn’t help reduce energy consumption
What excellent insight, sir! Is an automatic control valve required for this bypass? Is it significant? Additionally, is the DG-type horizontal centrifugal multi-stage boiler make-up water pump suitable for use with variable frequency at high frequencies? ?
Energy consumption should give way to stable operation