Variable-frequency pump
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Use a variable-frequency pump to control the liquid level in the reactor! When the set liquid level is reached, the control valve of the variable-frequency pump opens! But the liquid level remains unchanged until the valve is opened to 100% (usually 20% is sufficient), at which point the liquid level drops to zero instantly! The level gauge is fine, and the valve opening is also okay! The pump is fine too!
Is it true that when the pump’s speed is below the rated frequency, its head is insufficient to meet the pressure required in the external pipelines? In such cases, no flow can occur no matter what adjustments are made; only when the pump’s speed reaches the rated frequency does its head become sufficient to match the pressure in the outlet pipelines, at which point the fluid is delivered quickly and the liquid level drops. If that is the case, variable frequency drive installation is not possible. When installing a variable frequency drive, there must be sufficient head margin.
It is best for variable-frequency pumps to have manual control of the speed, with the control valve opened fully for adjustment
A variable-frequency pump is used to adjust the speed of the motor, not the valves; the valves are kept fully open after the pump starts operating, and adjustment is done via variable frequency