Principle of centrifugal compressor: from structure to workflow analysis

Centrifugal compressor is known as the “heart” of large-scale chemical industry, air separation device and other industrial fields. This kind of equipment that relies on high-speed rotating impeller is playing an increasingly important role. Different from screw compressor and reciprocating compressor, the principle of centrifugal compressor is to increase the pressure by “accelerating gas”. This essential difference determines its uniqueness in performance characteristics and application scenarios.
First, the principle of centrifugal compressor
The working process of centrifugal compressor can be summarized as three key steps of “acceleration-expansion-pressurization”, which is essentially an engineering application of “kinetic energy-potential energy conversion law” in fluid mechanics.
1. Impeller acceleration
After the gas enters from the axial inlet of the compressor, the first thing it encounters is the impeller rotating at high speed.
When the motor drives the impeller to rotate at a speed of tens of thousands of revolutions per minute, the blades do work on the gas, and the gas is “thrown” to the outer edge of the impeller under the action of centrifugal force. In this process, the speed of gas increases sharply and a lot of kinetic energy is obtained.
2. Diffuser deceleration
After leaving the impeller, the high-speed gas enters the diffuser. When the gas flows through the diffuser, the cross-sectional area of the flow passage increases, and the gas velocity gradually decreases. According to Bernoulli’s principle, the decrease in velocity means that the kinetic energy decreases and the static pressure increases. This process completes the key conversion from kinetic energy to pressure energy, which is the core link of centrifugal compressor pressurization.
3. Volute
The high-pressure gas after diffusion then flows into the volute, and the function of the volute is to collect and guide the gas evenly to the compressor outlet and send it to the subsequent pipeline or the next stage impeller.
Second, the detailed explanation of the core components
The performance of centrifugal compressor depends largely on the design and manufacturing accuracy of its core components. The following is the functional analysis of the main components:
-Impeller (working wheel): the core working part, usually made of high-strength alloy, is the core of high-speed rotation and is responsible for exerting centrifugal force and giving kinetic energy to gas.
-Spindle: it connects the driving source (motor, steam turbine) and the impeller, transmits torque and drives the impeller to do high-speed rotation. It is the core shaft for power transmission.
-Diffuser: located at the outlet of the impeller, with a gradually expanding channel. The function is to reduce the gas velocity, convert the kinetic energy of high-speed gas flow into pressure energy, and realize initial pressurization.
-Volute: collect the pressurized gas output by the diffuser, further stabilize the pressure and guide the flow, and at the same time complete the conversion of residual kinetic energy into pressure energy, and then transport the gas to the outlet pipeline smoothly.
-Air inlet chamber, bend and reflux device: the supporting parts of multi-stage centrifugal compressor, which are responsible for smoothly introducing the gas compressed in the previous stage into the next stage impeller to realize step-by-step pressurization and meet higher pressure requirements.
-Seals, bearings: seals prevent gas leakage and lubricating oil from entering the gas chamber; Bearings support the high-speed rotating spindle, reducing friction loss and ensuring the running accuracy of the equipment.
The working principle of centrifugal compressor seems to be simple-“rotating acceleration, expanding pressure and boosting”, but it is combined with multidisciplinary knowledge such as fluid mechanics, material science and control theory. For the equipment selector, understanding this principle is helpful to:
Judging applicability: centrifugal compressor is selected for large flow (≥20m3/min), and screw or piston is selected for small flow;
Fault prevention: understand surge and take protective measures;
Optimal operation: reasonably match the resistance of pipe network to avoid deviating from better working conditions;
The above is an introduction to the principle of centrifugal compressor: from structure to workflow analysis. Mastering its core principle is not only helpful for equipment selection, but also provides strong support for energy saving and sustainable development of enterprises. Turbo-Tech centrifugal compressor plays an irreplaceable role in petrochemical, air separation, metallurgy and other key fields with its advantages of large flow, smooth operation, oil-free lubrication, high efficiency and long life.