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Centrifugal air compressor: why does centrifugal air compressor not use frequency conversion control

Centrifugal air compressor is a speed compressor, driven by the impeller gas to do high-speed rotation, so that the gas produces centrifugal force, because of the gas in the impeller diffuser flow, so that the flow rate and pressure of the gas through the impeller is improved, continuous production of compressed air. Compus compressor introduces why centrifugal air compressor does not use frequency conversion control.

 

Centrifugal air compressor depends on the change of kinetic energy to improve the pressure of gas. When the bladed rotor (the working wheel) turns, the blades turn the gas, transferring work to the gas so that the gas gains kinetic energy. After entering the stator part, due to the stator's diffuser action, the speed and energy indenter is converted into the required pressure, and the speed decreases and the pressure increases. At the same time, the stator part's guiding effect is used to enter the impeller below and continue to boost the pressure, which is discharged from the volute.

Frequency conversion control for screw compressor is very effective, through pressure feedback, frequency conversion to speed regulation. Screw type "the change of speed has nothing to do with the exhaust pressure", and the centrifugal air compressor is "the exhaust pressure changes with the change of speed". That is, as the speed of the centrifuge drops, so does its pressure. Therefore, when the tail end needs a certain degree of pressure, the capacity regulation of centrifugal air compressor cannot be controlled by frequency conversion.

The capacity regulation mode of centrifugal air compressor mainly depends on the control of the opening size of the inlet guide blade to control the air intake, and the measures of venting or reflux. The adjustable range of centrifugal air compressor itself is generally about 70%. Even if frequency conversion control is used, it can not be less than the limit flow of centrifugal air compressor, otherwise, it is easy to produce "surge".

The impact of surge on centrifugal air compressor is very great, which can not be eliminated from the design of the machine. I won't repeat it here. The way to prevent "surge" is to increase the flow.

Shijiazhuang Compus Compressor Co., LTD., founded in 2004, is a high-tech enterprise specializing in the research and development, production and sales of air compressors. Its main products are oil-free mobile machines, drilling air compressors, centrifugal air compressors, screw air compressors and so on. Welcome to consult and cooperate!