Air compressors are potent tools used in industrial applications and farming alike. There are two general principles of gas or air: dynamic compression and positive compression.
Examples of positive displacement include scroll compressors, piston compressors, and rotary screw compressors.
Dynamic compressors are sometimes known to as turbocompressors. Radially designed ones are known as centrifugal compressors.
The dynamic compressor operates at a constant pressure. The displacement compressor operates with low pressure.
Make sure you understand the principles behind each type of air compressors before you buy one. Here are the four basic types of air compressors.
Reciprocating Type of Air Compressors
Piston or reciprocating air compressors are found at home construction projects. At times at smaller work sites like the garages. These type of air compressors are not for consistent use. Unlike the rotary screw compressors.
They consist of many movable parts that the rotary screw compressor. These parts are oil lubricated for smoother movement.
A piston compressor air delivers gases at high pressure. It compresses and displaces the air using a piston driven crankshaft to achieve this.
Reciprocating air compressors come in single or multiple stage variations. They help determine the number of pressure rangers they can deliver.
If you need a lot of power, then the best option for you is the multi-stage reciprocating air compressor. They deliver more power required for extreme construction, like auto assembling and maintenance.
Multi-stage air compressors can hit up to 30 horsepower. But, single stage air compressors are for small projects like metalworking and woodworking.
Uses
A reciprocating compressor is used for low-velocity/ high-pressure applications – below 30 bars.
Piston air compressors have many industrial uses. You can use them in oil refineries, chemical plants, and natural gas processing and delivery.
Compressed gases also play an essential part in refrigeration technology. Here, the successive re-expansion of the gas after its compressed delivers the needed cooling effect.
A lot of compressed air applications make use of reciprocating air compressors. You can also use them in automotive workshops, agriculture, dental surgeries, and in diving.
Pneumatic tools (air-powered tools), like angle-grinders and drills, are essential in the industry. This is because they are safer and lighter than those using an electric motor.
Axial Compressor
This compressor is a dynamic type of compressor that pressurizes gases continuously. External changes such as inlet temperature affect this type of air compressor.
These type of compressors have an axial flow as the name suggests. The gas is delivered to the compressor shaft. It then goes through rows of stationary and rotating blades.
Kinetic energy is converted to pressure by the blades, and an inbuilt balancing drum offsets the resulting axial thrust.
Axial compressors are typically smaller, lighter, and more reliable than their centrifugal counterparts.
A multistage axial flow compressor contains more than one row of rotating blades. These blades operate in series on a separate rotor in a separate shell. The shell consists of stationary vanes that deliver the gas to each subsequent row of rotating vanes.
The fixed stators or vanes can be combined or fixed at a variable angle. Fixed and rotating blades are the basic types of blading designed for an axial flow compressor.
Uses
These type of compressors are widely used in steel mills, petrochemical plants, and refineries. Specifically, in refineries, axial flow compressors have replaced centrifugal units. They perfume various applications that the units formerly performed.
These type of compressors are also utilized in many applications. For example, in fluid catalytic cracking air, blast furnace air, dehydrogenation of propane and in the big volume air separation farms.
High-speed engines on planes and ships also use this type of air compressor. Their high reliability, high performance, and their flexibility in operation during the flight envelope make them perfect for areophane engines. Their ability to hit thousands of horsepower is another reason as to why they are reserved for areophane researches.
They have high-efficiency rates, but they cost more than any other type of air compressor.
Rotary Screw Compressor
This type operates on a rotary type positive displacement machinery. Rotary Screw Compressors are used in place of piston compressors when there is need of huge volume of high pressure, either to run top power air tools like the jackhammer or for large industrial uses.
Unlike piston compressors, rotary screw compressors compress gases continuously resulting in minimal pulsation or surging of flow.
An Oil-free compressor compresses the gas completely without the help of an oil seal but through the action of the screws. As a result, their ability to reach optimum discharge pressure decreases. Nonetheless, multi-stage oil-free compressors compress the gas using multiple sets of screws can attain pressures surpassing 150psig, and volume output of over 2000 cubic feet each minute.
Fields that need no oil contact use an oil-free rotary screw compressor. They’re also used for long-lasting applications with high velocity 7/8 bars /low-pressure.
Medical research and semiconductors manufacturing industries use oil-free compressors.
The cavity compressions are injected with oil to seal and to cool the gas in an oil-injected compressor. It’s then isolated from the outlet for cooling, filtration, and recycling.
The depolarized particulates from the air are stick onto the oil. This action reduces the overloading of particles in the compressed air.
Some oil compressors can be used in the compressed gas flow below the compressor. But a lot of applications correct it by filter vessels.
Some also rectify this by using collecting tanks which decrease the local velocity of the air compressed. This action allows the oil to condense and leave the mainstream of the compressed gas system through the condensing device.
Industrial Applications
Rotary screw compressors are positive displacement, as mentioned above. Many manufacturing industries utilize them.
If you come to see a large manufacturing building, in most instances, rotary screw compressors are assisting in production processes. The justification for this is a rotary screw compressor has a complete cycle of duty, and it operates nonstop.
Some of the industrial applications include:
1. Household Appliance
2. Electronic and Electrical
3. Textile industry
4. Metallurgy and Mining
5. Printing and papermaking
6. Electric Power
7. Light Industry and Food
8. Medicine and Health
9. Petrochemical Engineering
10. Transportation
11. Mechanical and Electrical Machinery
12. Construction and Building Material
Centrifugal Compressors
This is a type of turbo or dynamic compressor. They are radially designed. This compressor relies on the rotating impeller energy transfer to the air.
A Dynamic compressor performs at a steady pressure. External conditions of incoming temperature variations influence its performance. On the other hand, displacement compressors only deliver at a constant flow.
Also, this compressor is for greater capacity due to its continuous flow through the compressor.
Their maintenance cost is low compared to reciprocating or rotary screw compressors, and some types can produce oil-free air.
These type of compressors work by slowing and cooling the incoming air via a diffuser to generate potential energy. Before the gas flows into the impellers center, kinetic energy converts into pressure in the diffuser. Air then flows into the impeller center containing radial vanes. It is then directed towards the impeller by the centrifugal forces.
Centrifugal compressors can produce high amounts of energy in a relatively small machine. This is due to their multi-phase compression processes.
Each stage depends on the compressor unit general pressure rise. Many steps are put in series to gain a greater pressure relying on the pressure needed.
Uses
They are used in construction sites such as in the steel manufacturing centers or the chemical plants. This is because their horsepower can reach 1,000.
Multi-stage is applied in industrial processes, gas, and oil applications. While Single-stage application is implemented in low pressure and in the treatment of wastewater. They help reach the required pressure ratio.
Ultra-high electric motors drive impellers in the current configurations of centrifugal air compressors. This driving action leads to a compact air compressor which has no related oil-lubrication systems and no gearbox. This makes it free of oil and suitable for projects that need perfect oil-free air.
The Bottom Line
The popularity of these compressors depend on the mentioned differences and functionalities. Thus, you should choose the appropriate type based on your needs.
Put the air supply you need. Do you need pressurized air for specific uses? You should check this in the specification. Air is measured in cubic per minute.
Fields that need no oil contact use an oil-free rotary screw compressor. They’re also used for long-lasting applications with high velocity 7/8 bars /low-pressure.
On a similar note, oil-injected screw compressors are more energy efficient than the piston type. It works quietly and provides large amounts of pressurized air a moderately low temperature.
Lastly, a reciprocating compressor is used for low-velocity/ high-pressure applications – below 30 bars.
Wrap-Up
As you have noticed, air compressors differ in a lot of ways. Each contains their compression stages, lubrication methods, and cooling methods. Furthermore, they vary according to how each operates and drive modes.
After reading this article, you’re now in a position to make the right choice of the type of air compressors that meet your requirements.
Please explore the other sections of our blog for more insightful information about air compressors.
