1. Understand the principle of centrifugal air compressor
The centrifugal air compressor is a speed type compressor. The impeller drives the gas to rotate at a high speed to generate centrifugal force. Due to the diffusing flow of the gas in the impeller, the flow rate and pressure after the gas passes through the impeller are improved, and the production is continuously performed. Compressed air.
Centrifugal air compressors rely on changes in kinetic energy to increase the pressure of the gas. When the bladed rotor (ie, the working wheel) rotates, the blade drives the gas to rotate, transferring work to the gas, and the gas gains kinetic energy. After entering the stator part, the speed energy head is converted into the required pressure due to the expansion of the stator, the speed is reduced, the pressure is increased, and the guiding action of the stator part is used to enter the lower stage impeller to continue to increase the pressure, and finally discharged by the volute .
2. Why can't it be unnecessary?
The frequency conversion control is very effective for the screw compressor. Through the pressure feedback, the frequency conversion adjusts the speed of the speed. The screw type "the change in the rotational speed is independent of the exhaust pressure", while the centrifugal type is "the exhaust pressure changes with the change in the rotational speed". That is, the rotation speed of the centrifuge drops, and the pressure also decreases. Therefore, when a certain degree of pressure is required at the end, the capacity adjustment of the centrifugal compressor cannot be controlled by frequency conversion.
The capacity adjustment mode of the centrifugal air compressor mainly controls the intake air amount by controlling the opening of the intake air guide vane, and the venting or recirculating measures. The adjustable range of the centrifuge itself is generally about 70%-100%. Even if the inverter control is used, it can't be smaller than the minimum flow of the compressor (or because the back pressure of the compressor is higher than its maximum discharge pressure). Otherwise, it is easy to produce " Surge".
