Built-in pressure balance structure of screw compressor

Abstract

The application relates to the technical field of screw compressors, in particular to a built-in pressure balance structure of a screw compressor, which can simplify the complexity of sealing, has a simple structure, reduces cost, and improves safety and reliability, and comprises a compressor shell, a female rotor and a male rotor are installed in the compressor shell, an air inlet and an air outlet corresponding to the female rotor and the male rotor are arranged on the compressor shell, are located on the air exhaust side, an air exhaust gap is left between the inner wall of the compressor shell and the female rotor and the male rotor, a uniform pressure cavity in communication with the air exhaust gap and a flow guide groove in communication with the uniform pressure cavity are arranged on the inner wall of the compressor shell, the flow guide groove extends from the uniform pressure cavity to the low-pressure side, and the cross section of the flow guide groove is a right trapezoid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of screw compressors, in particular to a built-in pressure balance structure of a screw compressor. BACKGROUND

[0002] As a rotary positive displacement compressor, the screw compressor can compress multiple phases. However, when compressing gas medium containing solid particles, the balance cavity on the exhaust side of the screw compressor is blocked, which is a problem in the design of the shaft seal of the screw compressor. To solve this problem, the traditional method is to cancel the balance structure and use high-pressure gas or liquid for blocking and sealing to ensure sealing without causing blockage. However, this will greatly increase the consumption of sealing gas (or liquid), and also cause the sealing structures on the suction and exhaust sides to be different, greatly increasing the complexity of the sealing auxiliary system. SUMMARY

[0003] In order to solve the problems of complex sealing structure and high cost, the present application provides a built-in pressure balance structure of a screw compressor, which can simplify the complexity of the sealing structure, has a simple structure, reduces the cost, and improves the safety and reliability.

[0004] The technical scheme is as follows: a built-in pressure balance structure of a screw compressor, comprising a compressor shell, a female rotor and a male rotor are installed in the compressor shell, an air inlet and an air outlet corresponding to the female rotor and the male rotor are formed on the compressor shell, and the air outlet is located on the exhaust side; an exhaust gap is left between the inner wall of the compressor shell and the female rotor and the male rotor, characterized in that a plurality of pressure equalization cavities are formed in the inner wall of the compressor shell and are in communication with the exhaust gap, and a plurality of flow guide grooves are formed in the inner wall of the compressor shell and are in communication with the pressure equalization cavities, wherein the flow guide grooves extend from the pressure equalization cavities to the low-pressure side.

[0005] Further, the cross section of the flow guide groove is a right trapezoid.

[0006] The bottom angle a of the right trapezoid is 15-30°.

[0007] The diameter of the tooth tip circle of the female rotor and the male rotor is D, the bottom diameter is d3, the width of the pressure equalization cavity is h1, the depth of the pressure equalization cavity is b, the length of the bottom edge of the flow guide groove is a, the depth of the flow guide groove is c, and the width of the flow guide groove is h2. The above parameters satisfy the following conditions: h2=h1=0.01-0.02D, b=(d2-d1) / 2, a=0.02-0.04D, c=0.4-0.45D, d2-d1=0.015-0.025D, d1 is determined according to the shaft system design, and d3>d2.

[0008] With this invention, a pressure equalization chamber is opened at the exhaust end, allowing the high-pressure exhaust to expand and depressurize rapidly within the chamber. A guide channel is also provided, connecting to the pressure equalization chamber. The gas in the pressure equalization chamber is as close as possible to the intake pressure, achieving a pressure equalization effect. Pressure balance on both sides provides a sealing function, simplifying the sealing process, resulting in a simpler structure, reduced costs, and improved safety and reliability. Furthermore, the guide channel has a right-angled trapezoidal cross-section with a slope on the front side in the rotor's rotation direction, preventing blockage of the pressure equalization chamber and guide channel by solid microparticles. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention;

[0010] Figure 2 Cross-sectional views of the male and female rotors;

[0011] Figure 3 This is a schematic diagram of the equalizing chamber and the flow guide channel;

[0012] Figure 4 for Figure 1 Sectional view along the AA direction;

[0013] Figure 5 for Figure 4 Cross-sectional view along the BB direction;

[0014] Figure 6 for Figure 4 Enlarged cross-sectional view along the CC direction. Detailed Implementation

[0015] See Figures 1 to 6 As shown, a screw compressor with a built-in pressure balancing structure includes a compressor housing 1, a female rotor 2 and a male rotor 3 installed inside the compressor housing 1, an air inlet 4 and an exhaust port 5 corresponding to the female rotor 2 and the male rotor 3 respectively, located on the exhaust side, an exhaust gap 6 is left between the inner wall of the compressor housing 1 and the female rotor 2 and the male rotor 3, a pressure equalization chamber 7 communicating with the exhaust gap 6 and a guide groove 8 communicating with the pressure equalization chamber 7 are formed on the inner wall of the compressor housing 1, and the guide groove 8 extends from the pressure equalization chamber 7 to the low-pressure side.

[0016] The cross-section of the guide channel 8 is a right trapezoid, and the base angle α of the right trapezoid is 15-30°.

[0017] The diameter of the tooth top circle of the female rotor and the male rotor is D, the bottom diameter is d3, the width of the pressure equalizing cavity is h1, the depth of the pressure equalizing cavity is b, the length of the bottom edge of the flow guide groove is a, the depth of the flow guide groove is c, and the width of the flow guide groove is h2, and the above parameters satisfy the following conditions: h2=h1=0.01-0.02D, b=(d2-d1) / 2, a=0.02-0.04D, c=0.4-0.45D, d2-d1=0.015-0.025D, the rotor shaft diameter d1 is determined according to the shaft system design, and d3>d2.

[0018] The high-pressure gas on the exhaust side of the traditional built-in balance structure leaks from the exhaust gap 6 to the shaft seal, and if the gas contains dust particles, the shaft seal will be blocked, the present application opens a pressure equalizing cavity 7 on the exhaust end of the compressor shell 1, which is a circular ring structure, so that the high-pressure exhaust gas expands rapidly in the pressure equalizing cavity 7. In order to make the high-pressure gas and the low-pressure gas mix well, the pressure drop reaches the expected result as much as possible, the present design is that the depth of the pressure equalizing cavity 7 is b (i.e. the difference between the inner and outer diameters of the circular ring is b), and the width of the pressure equalizing cavity 7 is h1. At the same time, in order to achieve pressure equalization as much as possible, a flow guide groove 8 is also opened on the compressor shell 1, so that the flow guide groove 8 communicates with the pressure equalizing cavity 7. In order to make the gas in the pressure equalizing cavity 7 as close to the suction pressure as possible, the flow guide groove 8 extends from the pressure equalizing cavity 7 to the suction side (low-pressure cavity), and the flow guide groove 8 is opened to a depth of c, a bottom edge length of a, and a width of h2. Because the gas contains solid micro-particles, in order to prevent the pressure equalizing cavity 7 and the flow guide groove 8 from being blocked by solid micro-particles, a slope is arranged on the front side in the direction of rotation of the rotor, and the slope angle is α, Figure 6 The flow guide groove section at the male rotor is given, and the flow guide groove section at the female rotor is axisymmetric with that at the male rotor.

[0019] The present application adopts air pressure balance to mix the high-pressure gas on the exhaust side with the low-pressure gas through the pressure equalizing cavity, and then communicates with the low-pressure cavity through the flow guide groove, so that the gas pressure in the pressure equalizing cavity is close to the suction side pressure, pressure equalization is achieved, the shaft neck pressure on the exhaust side is effectively reduced, it is not easy to be blocked by solid particles, the structure is low in complexity, the possibility of installation failure and subsequent operation failure is reduced, installation is simpler, and cost is reduced.

Claims

1. A built-in pressure balance structure of a screw compressor, comprising a compressor housing, a female rotor and a male rotor installed in the compressor housing, an air inlet and an air outlet corresponding to the female rotor and the male rotor are formed on the compressor housing, and an air discharge gap is left between the inner wall of the compressor housing and the female rotor and the male rotor. The compressor housing inner wall is provided with a circle of pressure equalizing cavities communicated with the exhaust gap, and flow guide grooves communicated with the pressure equalizing cavities, the flow guide grooves extend from the pressure equalizing cavities to the low pressure side, the cross section of the flow guide grooves is right trapezoid, the diameter of the tooth top circle of the female rotor and the male rotor is D, the bottom diameter is d3, the pressure equalizing cavity width is h1, the pressure equalizing cavity depth is b, the flow guide groove bottom side length is a, the flow guide groove depth is c, the flow guide groove width is h2, and the following conditions are met: h2=h1=0.01-0.02D, b=(d2-d1) / 2, a=0.02-0.04D, c=0.4-0.45D, d2-d1=0.015-0.025D, d1 is determined according to the shaft system design and d3>d2.

2. A built-in pressure balance structure of a screw compressor according to claim 1, characterized in that, The bottom angle α of the right trapezoid is 15-30°.

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