Air compressor selection and energy saving methods

Air compressor selection and energy saving methods

Air compressor selection and energy saving methods

I. Overview

Among many commonly used energy sources, compressed air can be said to be one of the popular energy sources second only to electricity. Although the use of compressed air has not yet penetrated into ordinary households like electricity, but the industry, mining, engineering, medical industry and even Agriculture has increasingly extensive uses, especially in the industrial world. The amount of use is extremely considerable, mainly because it has the following characteristics that other energy sources cannot replace:

1. No pollution or low pollution. In the era of high environmental protection awareness, compressed air is taken from the atmosphere and returned to the atmosphere. It does not need to be recycled and will not cause pollution at all (the oily compressed air after separation and filtration will have traces Oil and gas, even if there is a leak, there is no concern about environmental pollution.

2. In the production process, compressed air can directly contact most of the products to transmit power without harming the products.

3. It has no spontaneous combustion and is not easy to cause public accidents. Except that the pressure vessel needs to be set up and regularly inspected in accordance with regulations, there is no concern about pollution or electric shock.

4. The temperature is not high, and it is not easy to cause major injuries such as burns and scalds.

5. Separation technology can be used to produce nitrogen, oxygen, hydrogen nitrogen or rare gases for special purposes.

6. Provide non-energy uses, such as specific uses such as human breathing, water treatment, fermentation, and chemical reactions.

In view of the fact that compressed air has been widely used in all walks of life, the use of compressed air is increasing rapidly under the prerequisite of large-scale factories and automation, and while air compressors produce energy/compressed air, they are also in large quantities. Taking the most common 100PSIG (7kg/cm2G) compressed air system as an example, it takes about 20HP of energy to produce 100ICFM of compressed air. In the current industry, thousands of horsepower or even tens of thousands of horsepower air compressors are frequently used. There are so many factories in, how to save such a huge energy consumption is indeed a subject worthy of consideration for the industry.

Most air compressors are driven by motors. A very small number of air compressors are driven by steam turbines or gas turbines. When there is excess steam or gas (exhaust gas) is available The industries that use turbines to drive air compressors do have great energy-saving effects. There are not many cases of using turbine drive. The drive mode of the hollow compressor in the following description will be specifically referred to as motor drive.

Two, the type of air compressor

1. In the process of compressing air, air compressors are classified according to whether the air is mixed with lubricating oil. They can be divided into oil-free and oil-free air compressors. Lubricating oil can lubricate and cool any mechanical equipment. For oil-type air compressors, lubricating oil also has an air-tight effect to improve the volumetric efficiency of the air compressor. Therefore, from the perspective of energy saving, the energy efficiency of oil-type air compressors will definitely be higher than Oil-free air compressor. It is undeniable that the oil and gas in the compressed air will cause a lot of troubles in use. Even after the treatment of the precision filter, it cannot reach the completely oil-free state. Although the energy efficiency of the oil compressor is higher, the precision filter The purchase cost of the filter and the pressure loss and energy loss caused by the precision filter are also considerable. Unless the pneumatic equipment can accept oily compressed air or the use of compressed air is small, most users, especially industrial The world has discarded oil-type air compressors. Therefore, in the following chapters, the analysis and introduction of oil-free air compressors will be the main focus.

2. The air compressor can be divided into a fixed displacement air compressor (Positive Displacement Compressor) and a kinetic energy air compressor (Dynamic Compressor).

(A) The common feature of fixed-displacement air compressors is to use the air compressor to apply mechanical work to the air enclosed in a certain volume to "compress" the air volume and increase the pressure. This type of air compressor reciprocates Reciprocating and Rotory Screw are the most representative and popular.

(B) Any indirect "compression" of the volume of air to increase the pressure can be classified as a kinetic air compressor. There are many special publications on kinetic air compressors, so I won't repeat them here. In terms of its popularity and energy saving, it is introduced that when pushing centrifugal air compressors are the mainstream, in fact, centrifugal air compressors can be divided into multi-stage coaxial (Milti-Stage In-line) and gear-increasing type ( Integral Gear) mainly two kinds. Compared with the multi-segment coaxial type and the gear-increasing type, the multi-segment coaxial type is much larger than the gear-increasing type in terms of volume and weight. Of course, besides the higher cost, its energy efficiency is far less than that. Gear-increasing speed type, therefore, its traces can be seen in the use of super large air volume (the market segment is about 100,000CFM / 170,000CMH) compressed special gas (gas other than air or nitrogen). The common models on the market are The first gear-increasing centrifugal air compressor is the representative of kinetic energy air compressor.

3. Introduction to the advantages and disadvantages of reciprocating air compressors

In the process of industrialization, the reciprocating air compressor was one of the first air compressors to ask the market. Its contribution to the industry is indelible, even if it has lost its former style, it is gradually being spiraled, The centrifugal air compressor has replaced the dominant position, but it still has a certain living space. It can be seen that it still has some unique superior characteristics that other types of air compressors cannot completely surpass or replace.

The advantages are:

1. The intake and exhaust pressures cover a wide range, which can meet the demand of more than 4,000PSIG (280kg / cm2G)　.

2. The coverage of air volume is also quite wide. Although the application of large air volume has been gradually replaced by other types of air compressors and withdrawn from the market, the application range of small air volume (several horsepower or even smaller) still has considerable scope. The advantages.

3. In the application field of small air volume and high pressure, the reciprocating air compressor can be used as a booster.

4. Taking 100PISG (7kg / cm2 G) as an example, the performance of a two-stage compression reciprocating air compressor is quite superior in terms of energy efficiency, and its polytropic efficiency (Polytropic Efficiency) 　 can reach about 87%, this standard It is also the target for other types of air compressors to pursue breakthroughs.

5. The air tightness is quite good, so it is also suitable for special gases other than compressed air or nitrogen.

6. When adopting a high-strength (Heavy Duty) design, the speed is low, sturdy and durable, and the failure rate of continuous use is low.

7. Each stage of multi-cylinder (Multi-Cylincler) double-acting (Double Acting) design can adopt multi-step (Multi-Step Control) volume control mode, which can be used in compressed air systems that are extremely unstable in compressed air consumption The 0-50-100% three-step control type or the 0-25-50-75-100% five-step control type have significant benefits for throttling control.

I. Overview

Among the many energy sources that have been used, compressed air can be said to be one of the popular energy sources second only to electricity. Although the use of compressed air has not yet penetrated into ordinary households like electricity, but the industry, mining, engineering, and medical industries Even agriculture has increasingly wide-ranging uses, especially in the industrial world. The usage is extremely considerable, mainly because it has the following characteristics that other energy sources cannot replace:

1. No pollution or low pollution. In the era of high environmental protection awareness, compressed air is taken from the atmosphere and returned to the atmosphere. It does not need to be recycled and will not cause pollution at all (the oily compressed air after separation and filtration will have traces Oil and gas, even if there is a leak, there is no concern about environmental pollution.

2. In the production process, compressed air can directly contact most of the products to transmit power without harming the products.

3. It has no spontaneous combustion and is not easy to cause public accidents. Except that the pressure vessel needs to be set up and regularly inspected in accordance with regulations, there is no concern about pollution or electric shock.

4. The temperature is not high, and it is not easy to cause major injuries such as burns and scalds.

5. Separation technology can be used to produce nitrogen, oxygen, hydrogen nitrogen or rare gases for special purposes.

6. Provide non-energy uses, such as specific uses such as human breathing, water treatment, fermentation, and chemical reactions.

In view of the fact that compressed air has been widely used in all walks of life, the use of compressed air is increasing rapidly under the prerequisite of large-scale factories and automation, and while air compressors produce energy/compressed air, they are also in large quantities. Taking the most common 100PSIG (7kg/cm2G) compressed air system as an example, it takes about 20HP of energy to produce 100ICFM of compressed air. In the current industry, thousands of horsepower or even tens of thousands of horsepower air compressors are frequently used. There are so many factories in, how to save such a huge energy consumption is indeed a subject worthy of consideration for the industry.

Most air compressors are driven by motors. A very small number of air compressors are driven by steam turbines or gas turbines. When there is excess steam or gas (exhaust gas) is available The industries that use turbines to drive air compressors do have great energy-saving effects. There are not many cases of using turbine drive. The drive mode of the hollow compressor in the following description will be specifically referred to as motor drive.

Two, the type of air compressor

1. In the process of compressing air, air compressors are classified according to whether the air is mixed with lubricating oil. They can be divided into oil-free and oil-free air compressors. Lubricating oil can lubricate and cool any mechanical equipment. For oil-type air compressors, lubricating oil also has an air-tight effect to improve the volumetric efficiency of the air compressor. Therefore, from the perspective of energy saving, the energy efficiency of oil-type air compressors will definitely be higher than Oil-free air compressor. It is undeniable that the oil and gas in the compressed air will cause a lot of troubles in use. Even after the treatment of the precision filter, it cannot reach the completely oil-free state. Although the energy efficiency of the oil compressor is higher, the precision filter The purchase cost of the filter and the pressure loss and energy loss caused by the precision filter are also considerable. Unless the pneumatic equipment can accept oily compressed air or the use of compressed air is small, most users, especially industrial The world has discarded oil-type air compressors. Therefore, in the following chapters, the analysis and introduction of oil-free air compressors will be the main focus.

2. The air compressor can be divided into a fixed displacement air compressor (Positive Displacement Compressor) and a kinetic energy air compressor (Dynamic Compressor). The advantages and disadvantages of each type of air compressor will be introduced separately later.

(A) The common feature of fixed-displacement air compressors is to use the air compressor to apply mechanical work to the air enclosed in a certain volume to "compress" the air volume and increase the pressure. This type of air compressor reciprocates Reciprocating and Rotory Screw are the most representative and popular.

(B) Any indirect "compression" of the volume of air to increase the pressure can be classified as a kinetic air compressor. There are many special publications on kinetic air compressors, so I won't repeat them here. In terms of its popularity and energy saving, it is introduced that when pushing centrifugal air compressors are the mainstream, in fact, centrifugal air compressors can be divided into multi-stage coaxial (Milti-Stage In-line) and gear-increasing type ( Integral Gear) mainly two kinds. Compared with the multi-segment coaxial type and the gear-increasing type, the multi-segment coaxial type is much larger than the gear-increasing type in terms of volume and weight. Of course, besides the higher cost, its energy efficiency is far less than that. Gear-increasing type, therefore, it can be seen in the use of super large air volume (the market segment is about 100,000CFM / 170,000CMH) compressed special gas (gas other than air or nitrogen), and the common models on the market are The first gear-increasing centrifugal air compressor is the representative of the kinetic air compressor, and this type of air compressor will be the main introduction object in the following text.

3. Introduction to the advantages and disadvantages of reciprocating air compressors

In the process of industrialization, the reciprocating air compressor was one of the first air compressors to ask the market. Its contribution to the industry is indelible, even if it has lost its former style, it is gradually being spiraled, The centrifugal air compressor has replaced the dominant position, but it still has a certain living space. It can be seen that it still has some unique superior characteristics that other types of air compressors cannot completely surpass or replace.

The advantages are:

1. The intake and exhaust pressures cover a wide range, which can meet the demand of more than 4,000PSIG (280kg / cm2G)

　. 2. The coverage of air volume is also quite wide. Although the application of large air volume has been gradually replaced by other types of air compressors and withdrawn from the market, the application range of small air volume (several horsepower or even smaller) still has considerable scope. The advantages.

3. In the application field of small air volume and high pressure, the reciprocating air compressor can be used as a booster.

4. Taking 100PISG (7kg / cm2 G) as an example, the performance of a two-stage compression reciprocating air compressor is quite superior in terms of energy efficiency, and its polytropic efficiency (Polytropic Efficiency) 　 can reach about 87%, this standard It is also the target for other types of air compressors to pursue breakthroughs.

5. The air tightness is quite good, so it is also suitable for special gases other than compressed air or nitrogen.

6. When adopting a high-strength (Heavy Duty) design, the speed is low, sturdy and durable, and the failure rate of continuous use is low.

7. Each stage of multi-cylinder (Multi-Cylincler) double-acting (Double Acting) design can adopt multi-step (Multi-Step Control) volume control mode, which can be used in compressed air systems that are extremely unstable in compressed air consumption The 0-50-100% three-step control type or the 0-25-50-75-100% five-step control type have significant benefits for throttling control.