Working principle of centrifugal multistage compressor

In the scene of increasing demand for high-pressure gas in industrial production, centrifugal multistage compressor has become the key equipment in petrochemical industry, natural gas transportation, power generation and other fields by virtue of its core advantages of high-pressure output and stable operation. Turbo-Tech will disassemble the working principle of centrifugal multi-stage compressor in detail for you, and help industry practitioners to deeply understand the essence of equipment operation.
Working principle of centrifugal multistage compressor
First, the core energy conversion mechanism
Compared with single-stage centrifugal compressor, multi-stage structure breaks through the pressure limitation of single-stage compression by connecting multiple compression units in series, and at the same time, it takes into account the balance of flow and efficiency.
Centrifugal multi-stage compressor realizes gas pressurization by step-by-step conversion from kinetic energy to pressure energy, and its essence is the synergistic effect of gas dynamics and rotating machinery. Each stage of compression unit is composed of an impeller and supporting fixed elements, forming an independent energy conversion channel.
Impeller: As a working part, it is driven by a high-speed rotating spindle. After gas enters axially, it accelerates along the radial direction under the action of centrifugal force and blade thrust, and mechanical energy is converted into high-speed kinetic energy of gas.
Diffuser: located at the outlet of the impeller, the cross-sectional area of the flow passage gradually expands, and the gas flow rate decreases. According to Bernoulli’s principle, kinetic energy is converted into static pressure energy to improve the pressure.
Inter-stage diversion system: including bend and reflux device, which guides the gas to turn smoothly from the outlet of the previous stage diffuser and uniformly introduce it into the inlet of the next stage impeller to avoid turbulence and energy loss.
Each stage completes an “acceleration-deceleration-pressurization” cycle, and the gas pressure is accumulated step by step, and then collected by the volute and guided to the outlet.
Second, the functional division of multi-level structure
In the multi-level system, each level undertakes the task of differentiation, and the structural configuration accurately matches the airflow characteristics:
Level core component function description
The first stage, inlet chamber+impeller+diffuser, realizes uniform axial suction of gas, and completes initial kinetic energy injection and initial pressure rise;
The middle stage, impeller+diffuser+bend+reflux device, repeats the energy conversion process, and the diversion system ensures the accurate transition of airflow direction;
The last stage, impeller+diffuser+volute, completes the pressurization, and the volute decelerates the high-speed airflow and collects it into a stable outlet flow;
The impeller diameter, blade angle and rotating speed of each stage can be independently designed to meet the requirements of different pressure ratios, realize non-uniform compression ratio distribution and optimize overall efficiency.
Third, the working characteristics of centrifugal multistage compressor
Based on the above working principle, the centrifugal multistage compressor has the following core working characteristics:
1. Strong pressure improvement ability. By increasing the number of compression stages, higher outlet pressure can be achieved to meet the requirements of high-pressure process;
2. The operation stability is high, the multi-stage structure makes the gas pressure increase steadily step by step, reducing the impact of sudden pressure change on the equipment, and at the same time, the continuous gas flow mode also reduces the flow pulsation;
3. Good efficiency adaptability. By optimizing the structural parameters of impellers and diffusers at all levels, the compressor can maintain high compression efficiency in a wide working range, especially suitable for continuous operation scenes with large flow and high pressure.
It should be noted that in the process of multi-stage compression, the temperature will rise when the gas is compressed, and if the temperature is too high, it may affect the gas properties or damage the equipment parts. Therefore, in practical application, cooling devices are often installed between stages, so that the gas temperature drops before entering the next stage of compression, further improving compression efficiency and equipment reliability.
The above is an introduction to the working principle of centrifugal multistage compressor. Through the cooperative mechanism of “multistage impeller doing work+interstage energy conversion+precise guidance”, centrifugal multistage compressor realizes the gradual increase of gas pressure, and deeply understands its working principle, which is of great significance for equipment selection, operation and maintenance, optimization and upgrading.