Service Hotline: 800-803-8026(Fixed telephone)  400-603-8026(Mobile phone)

language
中国
韩国
韩国
韩国
韩国
韩国
 石家庄康普斯压缩机有限公司

新闻动态

imgboxbg

资讯详情

Comparison of performance characteristics, advantages and disadvantages of three compressors

  • Categories:Industry News
  • Author:
  • Origin:
  • Time of issue:2020-11-16 11:27
  • Views:

(Summary description)

Comparison of performance characteristics, advantages and disadvantages of three compressors

(Summary description)

  • Categories:Industry News
  • Author:
  • Origin:
  • Time of issue:2020-11-16 11:27
  • Views:
Information

1. screw compressor


Screw compressors are also called screw compressors. In the 1950s, oil-injected screw compressors were used in refrigeration devices. Because of their simple structure and few wearing parts, they can have low exhaust temperature under working conditions with large pressure differences or pressure ratios. The agent contains a large amount of lubricating oil (often referred to as the wet stroke), it is insensitive and has good air flow regulation. It quickly occupied the use range of large-capacity reciprocating compressors, and it continued to extend to the medium-capacity range. It is widely used in refrigeration equipment such as freezing, cold storage, air conditioning and chemical technology.

The screw heat pump with it as the main engine has been used in heating and air conditioning since the early 1970s. There are air heat source type, water heat pump type, heat recovery type, ice storage type and so on. In industry, in order to save energy, screw heat pumps are also used for heat recovery.

2.centrifugal compressor


A centrifugal compressor is a vane rotary compressor (that is, a turbo compressor). In a centrifugal compressor, the centrifugal force given to the gas by the high-speed rotating impeller and the diffuser effect given to the gas in the diffuser channel increase the gas pressure.

In the early days, because this compressor was only suitable for low, medium pressure and large flow occasions, it was not noticed by people. Due to the development of the chemical industry and the establishment of various large-scale chemical plants and refineries, centrifugal compressors have become a key machine for compressing and transporting various gases in chemical production, and occupy an extremely important position. With the achievements of aerodynamics research, the efficiency of centrifugal compressors has been continuously improved, and the development of key technologies such as high pressure sealing, small flow and narrow impellers, and multi-oil wedge bearings has solved the problem of high pressure and wide A series of problems in the development of flow range have greatly expanded the application range of centrifugal compressors, so that it can replace reciprocating compressors in many occasions, and greatly expand the application range.

3. reciprocating piston compressor


It is the earliest developed type of compressors. The wooden bellows invented in China in 1500 BC is the prototype of reciprocating piston compressors. At the end of the 18th century, Britain made the first industrial reciprocating piston air compressor. Labyrinth compressors began to appear in the 1930s, followed by various oil-free compressors and diaphragm compressors. The counter-acting structure that appeared in the 1950s greatly reduced the size of the large-scale reciprocating piston compressor, and realized multiple uses of a single machine.

Piston compressors have a long history of use and are currently the most used compressors in China. Due to its wide pressure range, it can adapt to a wide energy range, and has the advantages of high speed, multiple cylinders, adjustable energy, high thermal efficiency, and suitable for various working conditions; its disadvantages are complex structure, many vulnerable parts, and short maintenance cycle , Sensitive to wet stroke, impulse vibration, poor running stability.

Screw compressor is a new type of compression device. Compared with reciprocating type:

advantage:

①The machine has compact structure, small volume, less floor space and light weight.

②High thermal efficiency, fewer machining parts, and the total number of compressor parts is only 1/10 of the piston type. The machine has few wearing parts, safe and reliable operation, simple operation and maintenance.

③The gas has no pulsation, the operation is stable, and the unit has a low foundation, and no special foundation is needed. ④Inject oil into the rotor cavity during operation, so the exhaust temperature is low.

⑤Insensitive to wet stroke, wet steam or a small amount of liquid enters the machine, there is no danger of liquid shock.

⑥ It can be operated at a higher pressure ratio.

⑦The effective stroke of compression can be changed with the help of slide valve, and the stepless cooling capacity can be adjusted from 10 to 100%.

Disadvantages:

Complicated oil treatment equipment is required, and equipment such as oil separators and oil coolers with good separation effects are required. The noise is relatively large, generally above 85 decibels, and sound insulation measures are required.

Compared with the piston type, the centrifugal type has high speed, large air volume, less mechanical wear, less wearing parts, simple maintenance, long continuous working time, low vibration, stable operation, low basic requirements, and unit power when the air volume is The unit is light in weight, small in size, and occupies a small area. The gas volume can be adjusted steplessly in the range of 30% to 100%. It is easy to multi-stage compression and throttling. It can meet the requirements of certain chemical processes and is easy to realize automation. Large machines can be directly driven by economical industrial steam turbines, which has economic advantages for enterprises with waste heat steam. The disadvantages are: high noise frequency, large cooling water consumption, improper operation will cause surge.

Three common compression refrigerators (reciprocating, screw, centrifugal)

Comparison of performance characteristics

In the refrigeration system, because the reciprocating refrigeration compressor and the screw refrigeration compressor have different working principles, the reasons for their pressure loss and leakage loss are also different.

For reciprocating refrigeration compressors, the main factors affecting its pressure loss and leakage loss are the quality of the valve and the sealing performance when the valve is closed. This is because the suction valve has to overcome the spring resistance (compression spring) when the suction valve is opened and when the gas flows through the valve, due to the small passage section and high flow speed, a certain flow resistance is generated. Therefore, the reciprocating refrigeration compressor is During the suction process, the gas pressure in the cylinder is always lower than the gas pressure in the suction pipe; similarly, the gas pressure in the cylinder of the reciprocating refrigeration compressor is always higher than the gas pressure in the suction pipe during the exhaust process. If the passage section of the air valve is smaller, the resistance loss is greater. If the weight of the valve plate is large and the spring force of the valve is also large, the resistance loss will increase, and the pressure coefficient value will decrease.

For screw refrigeration compressors, the main reason affecting its pressure loss and leakage loss is the gas flow rate.

In screw refrigeration compressors, the performance of the screw is the key. If the tooth profile of the screw is a symmetrical arc type, its manufacture is simple. If the tooth profile of the screw is asymmetrical, its air delivery screw volume is large and the efficiency is high. If the length-to-diameter ratio of the screw is reduced, the screw can have good strength, increase the reliability of the operation of the screw-type refrigeration compressor, and facilitate the development of the screw-type refrigeration compressor in the direction of high pressure ratio.

In screw-type refrigeration compressors, two pairs of screws with the same diameter and length, and the pair with a larger rotor area utilization coefficient, have a larger displacement. On the surface, the larger the rotor area utilization coefficient, the better the performance of the screw refrigeration compressor. However, if the rotor area utilization factor is too large, the strength and rigidity of the screw will be reduced.

In the screw refrigeration compressor, reducing the number of teeth of the screw can increase the area between the teeth of the screw and increase the displacement of the screw refrigeration compressor. On the surface, the fewer the number of teeth of the screw, the better the performance of the screw refrigeration compressor. However, if the number of teeth of the screw is too small, the bending strength and rigidity of the screw will be reduced.

In screw refrigeration compressors, increasing the circumferential speed of the screw can reduce the size and quality of the screw refrigeration compressor, and the relative leakage of gas through the gap in the screw refrigeration compressor will be reduced. , Is beneficial to improve the volumetric efficiency and thermal efficiency of the screw refrigeration compressor. On the surface, the faster the circumferential speed of the screw, the better the performance of the screw refrigeration compressor. However, if the peripheral speed of the screw is too fast, it will correspondingly increase the gas flow loss in the peripheral speed between the suction and exhaust ports and between the teeth.

Among the three common refrigeration compressors (reciprocating, screw, and centrifugal), the inertia generated by reciprocating motion is the main disadvantage of reciprocating refrigeration compressors. Because they are often subjected to inertia caused by reciprocating motion, the valve and crank connecting rod mechanism in the reciprocating refrigeration compressor are most vulnerable to damage.

Among the three common refrigeration compressors (reciprocating, screw, and centrifugal), the huge noise generated during operation is the main disadvantage of screw refrigeration compressors. Because the refrigerant gas is often affected by the periodic high-speed passage of the suction and discharge ports, and the leakage through the gap, a reasonable screw operating speed must be selected in the screw refrigeration compressor.

Among the three common refrigeration compressors (reciprocating, screw, and centrifugal), surge is the main disadvantage of centrifugal refrigeration compressors.

The reason for the surge of the centrifugal refrigeration compressor is that when the cooling water inlet of the condenser is reduced to a certain extent, the flow rate of the centrifugal refrigeration compressor is reduced to a small amount, and serious gas desorption occurs in its passage. Flow, its outlet pressure suddenly drops. Although the centrifugal refrigeration compressor and the condenser work together, the pressure of the gas in the condenser is not reduced at the same time, so the pressure of the gas in the condenser is greater than the outlet pressure of the centrifugal refrigeration compressor, resulting in the condenser The gas in the refrigerant flows back into the centrifugal refrigeration compressor until the gas pressure in the condenser drops to equal to the outlet pressure of the centrifugal refrigeration compressor.

This is, the centrifugal refrigeration compressor starts to send air to the condenser again, the flow rate increases, and the centrifugal refrigeration compressor resumes normal operation. However, when the gas pressure in the condenser is also restored to the original gas pressure, the flow rate of the centrifugal refrigeration compressor decreases again, the outlet pressure of the centrifugal refrigeration compressor begins to drop, and the gas flows back again. This goes back and forth, producing periodic airflow oscillations. Therefore, in the centrifugal refrigeration compressor, the cooling water volume of the condenser should not be too small, otherwise it will cause strong vibration when the centrifugal refrigeration compressor is in operation, and even cause damage to the centrifugal refrigeration compressor in severe cases. Broken.

Xiaoqi summary: In the refrigeration system, because the three common refrigeration compressors (reciprocating, screw, centrifugal) have their own different characteristics. Therefore, they have their own advantages and their own shortcomings in performance.

Keyword:

Scan the QR code to read on your phone

 石家庄康普斯压缩机有限公司

Copyright:Shijiazhuang Comps Compressor Co., Ltd

冀ICP备15000208号-1       Poweredby:300.cn

石家庄康普斯压缩机有限公司