What is the working principle of centrifugal air compressor

What is the working principle of centrifugal air compressor? What are the application areas? The working principle of centrifugal air compressor = impeller kinetic energy + diffuser pressure exchange + multi-stage series pressurization + intermediate cooling power saving + anti-surge and reliable. Turbo-Tech will introduce the working principle and application fields of centrifugal air compressors in detail below.
Ⅰ. The difference between the working principle of centrifugal air compressor and the volumetric type
Volumetric air compressor (air compressor, screw air compressor): by reducing the space occupied by the gas to pressurize.
Power Air Compressor/Speed Air Compressor (Centrifugal Air Compressor, Axial Flow Compressor): Relying on the conversion of kinetic energy and pressure energy.
The centrifugal air compressor is the representative of the latter, through the high-speed rotating impeller to throw out the gas, in the process of throwing energy to the gas.
Ⅱ. Introduction to the core principle of centrifugal air compressor
To understand centrifugal air compressors, you only need to remember four words: accelerate first, then diffuse. The working process of the whole machine can be broken down into four steps:
1. Inhale
The gas enters the center of the impeller along the axial direction.
2. Accelerate work
The impeller is driven by a motor or steam turbine and rotates at a high speed of tens of thousands or tens of thousands of revolutions per minute. After entering the blade passage, the gas is carried to rotate together, and under the strong centrifugal force, it is thrown from the core of the impeller to the outer edge.
In this process, the impeller does work on the gas, the speed of the gas increases sharply (kinetic energy increases greatly), and the pressure also increases. The higher the circumferential velocity of the outer edge of the impeller, the more energy the gas has.
3. Diffusion
The high-speed air flow thrown out of the impeller then enters the diffuser, an annular channel with a gradually expanding cross-sectional area. As the channel widens, the airflow is forced to slow down, and the kinetic energy is converted into pressure energy, and the pressure increases significantly.
4. Compilation/
The gas then enters the spiral volute with a gradually expanding section, the flow rate is further, the pressure continues to increase, and then it is smoothly collected to the exhaust pipe for delivery.
Will single stage be enough? The pressure ratio of single stage impeller is limited. If a higher exhaust pressure is required, multi-stage impellers are used in series: after the gas is compressed at one stage, it enters the next stage to continue to pressurize. In order to save power and control temperature, intercoolers are usually installed between stages-cooling the gas and then compressing it, which can not only consume power, but also avoid excessive exhaust temperature.
Ⅲ. Introduction to the application field of centrifugal air compressors
Centrifugal air compressors are widely used in the following fields by virtue of the advantages of “large flow, oil-free and stable operation”:
1. Petrochemicals and Refining
The main fan of catalytic cracking unit, the circulating hydrogen compressor of hydrogenation unit, the ethylene unit (cracking gas compressor, propylene compressor, etc. in “three machines”), natural gas pressurization and pipeline transportation are almost inseparable from centrifugal compressors.
2. Air separation (cryogenic air separation)
The oxygen, nitrogen and argon needed by the iron and steel, chemical and electronic industries are all separated from the air by air separation units. The core raw material of the air separation unit is clean air compressed to a certain pressure-this step is completed by a large centrifugal air compressor.
3. Metallurgy and steel
It can be seen in blast furnace blowing (although axial flow is commonly used in super-large air volume, centrifugal type is commonly used in small and medium-sized blast furnaces and various combustion support and air supply links), converter gas recovery, oxygen station pressurization and other scenarios.
4. Electricity and Environmental Protection
Flue gas desulfurization and oxidation wind, denitrification and ammonia injection gas, instruments and compressed air for ash removal in thermal power plants; Combustion-supporting wind for waste incineration power generation; And sewage treatment aeration, the energy saving effect is remarkable.
5. Pharmaceuticals, Food and Electronics
These three industries have strict requirements on the oil content and cleanliness of compressed air. The centrifugal air compressor itself is oil-free (with rear drying, filtration, and system), and can meet the needs of high-quality gas sources for pharmaceutical production, food and beverage filling/fermentation, and electronic chip manufacturing.
6. Emerging areas
Emerging tracks such as carbon capture and storage (CCUS) and compressed air energy storage (CAES) also rely on high-flow centrifugal compression/equipment.
7. General industry
For intermediate air compressor stations in textile, glass, papermaking, automobile manufacturing and other industries, when the gas consumption scale reaches a certain level, it is a common and economical configuration combination to use centrifugal air compressors as “base load” and screw machines as “peak shaving”.
The above is the introduction to “What is the working principle of centrifugal air compressor? What are the application fields?” If you want to know more about centrifugal air compressor knowledge, welcome to consult us Turbo-Tech Sales.