CN1793654A - Double-screw compressor for high pressure system - Google Patents

Abstract

The invention discloses a twin-screw compressor used in a high-pressure system, which comprises a working chamber composed of intermeshed male rotors, female rotors and a housing; A shaft seal is arranged on the shaft extending outward, and the air intake and exhaust passages are arranged in the casing; the male rotor and the female rotor have bearings for bearing axial force and radial force respectively, and they are distributed in the male rotor and the female rotor. The two ends and the middle of the two ends and the middle; the male rotor and the female rotor both have two helical sections, and the two helical sections on one rotor have the same tooth shape and size, and the teeth correspond to each other and the helical direction is opposite; the helical The length to diameter ratio of the segment is 1:1~1:1.2, the number of teeth of the male rotor is 5 teeth or 6 teeth, the number of teeth of the female rotor is 7 teeth or 8 teeth, and the diameter of the dedendum circle of the female rotor is equal to or greater than that of the male rotor teeth Root circle diameter. Its exhaust pressure can reach up to 15MPa, and it can be widely used in high-pressure systems such as transcritical CO ₂ refrigeration, process compression, oil-gas mixed transportation, natural gas gathering and transportation, and high-pressure air compression.

Description

A twin-screw compressor for high-pressure systems

Technical field

The invention belongs to the technical field of mechanical engineering, in particular to a twin-screw compressor that can be widely used in high-pressure systems.

Background technique

Twin-screw compressor is a kind of volumetric compressor. Due to its advantages of simple structure, high reliability, convenient operation and maintenance, strong adaptability and multi-phase mixed transmission, it has been widely used. In aerodynamic devices and refrigeration devices with medium cooling capacity, it has become the mainstream model.

In the field of refrigeration, the replacement of Freon refrigerants is becoming more and more prominent. Among the many alternative refrigerants, CO ₂ refrigerants have attracted widespread attention in the industry. The transcritical CO ₂ unit has the advantages of high heat transfer coefficient and low compression ratio, but its working pressure is high, which can reach 15MPa, so it poses a challenge to the design and manufacture of the compressor, which is the heart of the unit. Existing twin-screw compressors are used in large temperature difference conditions such as air-cooled heat pumps and ice storage, or in systems using high-pressure refrigerants such as R410A. Due to the high discharge pressure, it not only increases the cost of the machine but also affects the application site. caused certain restrictions.

In the process of oil and natural gas extraction and transportation, due to the remoteness of oil and gas fields, natural gas and its mixture with crude oil and water need to be transported from the oil field to remote storage and processing sites for processing, which requires the use of high-pressure compressors in the pipeline transportation system. The fluid is pressurized.

In the field of aerodynamics, high-pressure air compressors with an exhaust pressure exceeding 3 MPa are currently reciprocating piston compressors. This type of compressor has poor reliability, low degree of automation, and large volume when it has a large flow rate. Therefore, there is an urgent need for a high-pressure screw compressor that can solve these problems in the field of aerodynamics.

The needs of these different fields make the design of compressors must be innovative. The main factor that limits the discharge pressure of the traditional twin-screw compressor is the problem of bearing life, especially the life of the bearing that bears the axial force of the male rotor. In order to cope with the large axial force of the male rotor, a large-sized axial force bearing is usually arranged on it, while the radial force bearing of the female rotor can only use a smaller size due to the limitation of the center distance between the two rotors. In this way, among all the bearings that bear the radial force of the rotor, the radial force on the discharge end of the female rotor is relatively large, while the radial force bearing used by it is very small, so its life is the shortest, which limits the overall performance of the screw compressor. machine life. In this case, the usual measure is to increase the number of bearings of the screw compressor, or add a complex balance piston system to offset part of the axial force of the male rotor, so that the compressor can withstand greater pressure and prolong its life. Furthermore, multi-stage compression can be used to achieve the required high pressure. These methods greatly increase the cost of manufacture and use. In addition, the rigidity of the rotor after stress under high pressure is also a problem. These circumstances make the current maximum operating pressure of twin-screw compressors usually less than 3Mpa, and its application in high-pressure systems is limited, making it difficult to greatly increase the operating pressure.

Contents of the invention

The object of the present invention is to provide a kind of twin-screw compressor for high-pressure system, and this twin-screw compressor can be widely used in high-pressure systems such as _CO Refrigeration, process compression, oil-gas mixed transportation, natural gas gathering and transportation, and high-pressure air compression.

In order to achieve the above object, the technical solution adopted by the present invention is: a twin-screw compressor used in a high-pressure system, including a male rotor and a female rotor that mesh with each other, and the male rotor, the female rotor and the housing together form a compressor for compressing gas Working chamber; the housing is provided with an air intake port and an exhaust port, the outer shaft of the male rotor is provided with a shaft seal, and the air intake and exhaust passages are arranged in the housing;

The male rotor and the female rotor have bearings for bearing axial force and bearings for bearing radial force, which are distributed at both ends and in the middle of the male rotor and the female rotor; the characteristics are as follows:

Both the male rotor and the female rotor are provided with two helical sections, the tooth profile and size of the two helical sections on the same rotor are the same, the teeth correspond to each other and the helical direction is opposite; the length and diameter ratio of the helical section is 1:1～1:1.2, the number of teeth of the male rotor is 5 teeth or 6 teeth, the number of teeth of the female rotor is 7 teeth or 8 teeth, and the diameter of the dedendum circle of the female rotor is equal to or greater than the diameter of the dedendum circle of the male rotor;

After the gas enters the shell through the suction port, it is divided into two paths, which are respectively inhaled and compressed by the two helical sections on the male rotor and the female rotor. After being discharged, they converge into one path in the shell and are discharged through the exhaust port.

The twin-screw compressor used in the high-pressure system of the present invention adopts the symmetrical arrangement of two helical sections with the same shape and size and opposite direction of rotation on the rotor, and the gas is divided into two paths to be sucked, compressed and discharged symmetrically in two sections , so the axial force of the gas on the rotor is symmetrical, the direction is opposite, and the pulse frequency is consistent, so that the axial force completely cancels each other and the vibration is reduced. The radial force of the rotor can be shared by three sets of radial force bearings at three fulcrums, so that the load on each bearing is greatly reduced. At the same time, the male and female rotors are designed with multiple teeth, and the length-to-diameter ratio of the helical section is 1:1~1:1.2, so that the diameter of the female rotor increases and the center distance of the rotor increases, so the radial force bearing of the female rotor can be equal to or greater than The male rotor bears the radial force distribution more reasonably, and also increases the rigidity of the rotor.

Due to the unique structural design of the invention, the axial forces of the rotors cancel each other and the radial forces are shared. The bearing arrangement breaks through the limitations of the traditional structure and can be reasonably configured according to the magnitude of the force. Therefore, the entire compressor can withstand greater pressure and pressure. Compared with the exhaust pressure, the highest exhaust pressure can reach 15MPa, and the vibration will be further reduced, and the manufacturing and use costs will be reduced, which can well meet the requirements of the high-pressure system for the twin-screw compressor.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention;

Fig. 2 is a schematic diagram of the gas channel of the present invention;

Fig. 3 is a schematic diagram of the layout of the male and female rotors of the present invention;

Fig. 4 is a schematic diagram of the teeth profile of the helical segment of the male and female rotors of the present invention.

The structural features and working principles of the present invention will be further described in detail below in conjunction with the accompanying drawings, and examples will be given to understand the implementation and features of the present invention more clearly.

Detailed ways

According to the technical solution of the present invention, a pair of intermeshing male rotors and female rotors together with the housing form a working chamber, the suction and exhaust passages are on the housing, and three sets of bearings are respectively installed on the male rotor and the female rotor, arranged on two At the end and in the middle, there is a shaft seal on the outstretched shaft of the male rotor.

The above-mentioned male rotor and female rotor have two helical sections on both the male rotor and the female rotor. The two helical sections on the same rotor have the same profile and the same size, and the length and diameter ratio of each helical section is 1:1~1. : 1.2, the direction of rotation of the two helical segments on each rotor is opposite, and the teeth of the two helical segments correspond one to one, and are arranged in a mirror image. This structure enables the rotor axial forces to completely cancel each other out.

The above-mentioned twin-screw compressor male rotor and female rotor have a multi-tooth scheme for the profile line of the helical section. For example, the male rotor has 5 or 6 teeth, and the female rotor has 7 or 8 teeth, so that the diameter of the female rotor increases, and the diameter of the dedendum circle can be increased. It is equal to or greater than the diameter of the dedendum circle of the male rotor, and the center distance is increased to facilitate the arrangement of larger-sized bearings.

There are three sets of bearings on each rotor of the above-mentioned twin-screw compressor, which bear radial force and axial force respectively. The radial force bearings are arranged at both ends and the middle of the rotor, and the axial force bearings are arranged at one of them; when the pressure is not high, the middle set of bearings may not be used, and only the bearings are arranged at both ends.

In the twin-screw compressor mentioned above, due to the mutual cancellation of the axial force, the diameter of the female rotor increases and the center distance increases, so the radial force bearing of the female rotor can be equal to or greater than that of the male rotor.

The gas inhaled by the air inlet of the twin-screw compressor is divided into two paths in the casing, which are respectively inhaled and compressed by two intermeshed helical sections of the rotor.

The high-pressure gas compressed by the above-mentioned screw compressor is discharged from the two helical parts of the rotor, and then merged into one path in the housing, and then discharged through the exhaust port.

The following are the specific examples given by the inventor:

Referring to Fig. 1 and Fig. 3, the present invention includes a pair of intermeshing male rotor 1 and female rotor 5. There are two helical parts a and b with opposite directions on the male rotor 1, and there are two corresponding helical parts a and b on the female rotor 2. To the opposite helical parts c and d. Three sets of bearings are respectively arranged on the male rotor 1 and the female rotor 5, the radial force bearing 3, the radial force bearing 12, and the radial force bearing 11 at the two ends and the middle of the male rotor 1, and the radial force bearings at both ends and the middle of the female rotor 5. Radial force bearing 4, radial force bearing 7, radial force bearing 8. And axial force bearing 9, axial force bearing 10. The axial force bearing 9 and the axial force bearing 10 can be arranged at the end of the rotor, or at the middle section of the rotor. The casing 6 with several components together with the male rotor 1 and the female rotor 5 constitutes the working chamber for gas suction, compression and discharge. There is a shaft seal 2 at the power input end where the male rotor 1 extends out of the housing 6 to separate the internal fluid from the outside.

Referring to Fig. 2, the intake and exhaust passages of the present invention are arranged in the housing 6, and there are two arrangements, as shown in Fig. 2(a): the gas enters from the suction port 13 and is divided into two paths, in the middle of the rotor The sections are respectively inhaled by two helical sections, discharged at both ends after being compressed, and merged into a route to be discharged from the exhaust port 14; as shown in Figure 2(b): the gas enters from the suction port 13 and is divided into two routes, at both ends of the rotor They are respectively inhaled by the two helical sections, and discharged in the middle section after being compressed, and merged into a route to be discharged from the exhaust port 14.

Referring to FIG. 3 , the present invention includes a pair of male rotor 1 and female rotor 5 meshing with each other. The male rotor 1 has two helical parts a and b in opposite directions, and the female rotor 5 also has two helical parts c and d in opposite directions. The direction of rotation of the helical part on the rotor can be combined in two ways, as shown in Figure 3(a) and (b). In addition, the two helical parts on the male rotor 1 and the female rotor 5 can be partially or completely disassembled on the rotor, such as parts a and c are detachable, b and d are integrated with the shaft; or b and d can be disassembled , a, c and the shaft are made into one; or the four helical segments can be disassembled, which is conducive to the standardization of parts.

Referring to Fig. 4, the profiles of the helical parts of the male rotor and the female rotor of the present invention adopt a multi-tooth structure, so that the rotor diameter and center distance are increased. The specific embodiment given by the present invention is: as shown in Figure 4 (a), the male rotor 1 tooth profile structure is made of 5 identical teeth, and the female rotor 5 tooth profile is formed of 7 identical teeth; as shown in Figure 4 (b ), the male rotor 1-tooth structure is composed of 6 identical teeth, and the female rotor 5-tooth structure is composed of 8 identical teeth. This method makes the tooth bottom circle diameter of the female rotor equal to or greater than that of the male rotor, thereby increasing the center distance between the two rotors and improving the rigidity of the rotor. The male teeth and the female teeth mesh with each other to form suction and exhaust chambers with the housing.

Claims (4)

1, a kind of double-screw compressor that is used for high-pressure system comprises intermeshing male rotor and female rotor, the active chamber that male rotor, female rotor and the paired gas of housing mutual group compress; Be furnished with intakeport and relief opening on the housing, the extension projecting shaft of male rotor is furnished with the axle envelope, and air inlet and air outlet flue are arranged in the housing;

Respectively be useful on the bearing that bears axial force and the bearing of bearing radial force on male rotor and the female rotor, they are distributed in the two ends and the centre of male rotor and female rotor;

It is characterized in that:

All have two sections spiral sections on described male rotor and the female rotor, with the flute profile of epitrochanterian two sections spiral sections and measure-alike, tooth correspondence and rotary orientation one by one is opposite; The L/D ratio of spiral section is 1: 1～1: 1.2, and the number of teeth of male rotor is 5 teeth or 6 teeth, and the number of teeth of female rotor is 7 teeth or 8 teeth, and the root diameter of female rotor is equal to or greater than the male rotor root diameter;

Gas is divided into two-way after intakeport enters housing, suck by two spiral sections on male rotor and the female rotor respectively and compress, after pressurized gas were after compression discharged by two spiral sections on male rotor and the female rotor, the Cheng Yilu that confluxes in housing discharged through relief opening.

As right 1 described high pressure double-screw compressor, it is characterized in that 2, the bearing that is used for bearing radial force on the described female rotor is equal to or greater than the bearing that is used for bearing radial force on the male rotor of corresponding position.

3. as right 1 described high pressure double-screw compressor, it is characterized in that when the pressure of high-pressure system hanged down, the bearing that is used for bearing radial force was arranged in two ends, the centre is not arranged.

4. as right 1 described high pressure double-screw compressor, it is characterized in that the spiral section on described male rotor and the female rotor can be dismantled.