A wet compression centrifugal compressor and intake air compression control method

Abstract

The present invention discloses a wet compression centrifugal compressor and an intake compression control method, the compressor comprising an impeller and a wheel cover, an intake air flow passage being formed between the wheel cover and the impeller, water spray holes for spraying liquid for cooling into the intake air flow passage are arranged in the direction of intake air flow on the wheel cover, the water spray holes are evenly distributed along the surface of the wheel cover, a nozzle is correspondingly arranged in each water spray hole, the nozzles are connected to a water volume server through a pipeline, a regulating valve for controlling the water spray volume is separately connected at the connection point, and the water spray volume at the water spray hole is controlled by the water volume server; along the air flow direction of the intake air flow passage; the present invention arranges a main vaporization water spray hole and a supplementary vaporization water spray hole on the wheel cover, so as to flexibly adjust the water spray volume, ensure that the air in the gas compression passage is close to saturated wet air, is suitable for variable frequency compressors, and the power saving will not be significantly reduced with changes in the operating conditions of the compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of centrifugal compressors, and in particular to a wet compression centrifugal compressor and an intake air compression control method. Background Art

[0002] Centrifugal compressors are widely used in industrial production due to their high single-stage pressure ratio and wide operating range. However, their power consumption at higher pressure levels is higher than that of oil-injected screw compressors of the same class. This is primarily because centrifugal compressors typically use adiabatic compression, which consumes a lot of power during the compression process.

[0003] The concept of wet compression was first proposed in the gas turbine field in the last century. This approach reduces the compression work required by injecting liquid droplets during the compression process, where the evaporation of the droplets absorbs heat. Current wet compression technologies can be categorized into three main types: inlet water injection, interstage water injection, and blade water injection. Compressor inlet water injection has a simple structure, but it is difficult to ensure optimal vaporization of the liquid during the entire compression process. Furthermore, inlet water injection can cause distortion in the compressor's intake air, impacting efficiency, and poses a risk of freezing in winter due to low inlet temperatures. Interstage water injection can lower the intake air temperature of subsequent stages and prevent freezing, but its power savings are lower than inlet water injection. Impeller water injection offers better results, but its structural complexity makes it difficult to apply to civilian applications. Furthermore, unlike the geared compressors of the last century, more centrifugal compressors now utilize variable-frequency motors to accommodate a wider range of operating conditions. Traditional fixed-volume water injection systems struggle to adapt to both winter and summer conditions, as well as to high and low load conditions. This significantly reduces the power savings of wet compression with water injection compared to the ideal optimal solution, and even creates the risk of downtime due to excessive water injection and insufficient aeration. Summary of the Invention

[0004] Technical purpose: In view of the shortcomings of the above-mentioned existing centrifugal compressor impeller water spraying, the present invention discloses a wet compression centrifugal compressor and an intake compression control method that can flexibly adjust the water spraying amount.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A wet compression centrifugal compressor comprises an impeller and a wheel cover, an inlet air flow passage is formed between the wheel cover and the impeller, water spray holes for spraying liquid into the inlet air flow passage for cooling the air are arranged on the wheel cover in the direction of the air flow, the water spray holes are evenly distributed along the surface of the wheel cover, a nozzle is correspondingly arranged in each water spray hole, the nozzles are connected to the water volume server through a pipeline, a regulating valve for controlling the water spray volume is separately connected at the connection point, and the water spray volume at the water spray hole is controlled by the water volume server; along the air flow direction of the inlet air flow passage, the water spray holes comprise a main vaporization water spray hole located near the inlet end of the inlet air flow passage and a supplementary vaporization water spray hole located inside the main vaporization water spray hole for supplementary water spray according to the relative humidity of the gas, the nozzle aperture in the main vaporization water spray hole is larger than the nozzle aperture of the supplementary vaporization water spray hole.

[0007] Preferably, in the present invention, the axis of the water spray holes near the gas inlet and outlet ends along the gas flow direction of the inlet flow duct is perpendicular to the wall surface of the inlet flow duct; the axis of the water spray holes in the middle area is parallel to the wall surface of the inlet flow duct, spraying liquid to cool the gas while suppressing leakage of the impeller blade tip gap.

[0008] Preferably, the present invention provides a humidity measuring point for detecting the humidity of the gas behind the corresponding water spray hole along the axial direction of the inlet air passage.

[0009] Preferably, the water spray holes in the same axial plane of the wheel cover of the present invention are arranged at 5%, 30% and 70% of the length of the intake air duct along the axial direction of the intake air duct, among which the water spray holes at the 5% length position serve as main vaporization water spray holes, and the water spray holes at the 30% and 70% length positions serve as supplementary vaporization water spray holes.

[0010] Preferably, the humidity measurement points of the present invention are set at 15%, 45% and 85% length positions of the axis of the intake air passage.

[0011] Preferably, the water spraying positions of the water spraying holes in front of the humidity measuring point positions of the present invention are staggered with each other in the circumferential direction.

[0012] Preferably, the axis of the water spray hole at the 30% length position of the present invention is parallel to the wall surface of the intake air channel, and the axis of the water spray hole at the 70% length position is perpendicular to the intake channel.

[0013] The present invention discloses an intake air compression control method for the wet compression centrifugal compressor, comprising the steps of:

[0014] S01. Dividing the centrifugal compressor into a normal operation zone and a near-surge zone according to operating conditions, setting corresponding water spray volumes, and determining the current operating zone of the compressor based on flow and pressure parameters during operation of the centrifugal compressor;

[0015] S02. Determine the corresponding maximum total water spray flow rate according to the suction flow rate;

[0016] S03. Within a range below the maximum total water spray flow rate, the water flow rate of the nozzle is distributed through the water volume servo, and the humidity of the gas is monitored through the humidity measurement points set on the wheel cover. The water flow rate of the nozzle is adjusted according to the monitoring results to make the humidity of the gas downstream along the air intake direction close to 99%.

[0017] Preferably, in step S02 of the present invention, when water is initially sprayed, if the operating area of ​​the centrifugal compressor is in the normal operating area, the maximum total water spray flow rate is set to 3% of the suction flow rate; if the operating area of ​​the centrifugal compressor is in the near-surge area, the maximum total water spray flow rate is set to 1% of the suction flow rate.

[0018] Preferably, in step S03 of the present invention, when the water spraying amount of the nozzle is adjusted according to the monitoring result of the humidity measuring point, when the average humidity value monitored by the humidity measuring point is lower than 95% or higher than 99%, the total water spraying flow rate is increased or decreased accordingly, and the gas humidity is controlled so that the average humidity value is in the range of 95%-99%; when the average humidity value is in the range of 95%-99%, the flow rate of the nozzle is adjusted according to the gas humidity monitored by the humidity measuring point downstream of the inlet flow duct, so that the downstream gas humidity approaches 99%.

[0019] Beneficial effects: The wet compression centrifugal compressor and intake air compression control method disclosed in the present invention have the following beneficial effects:

[0020] 1. The present invention provides a main vaporization water spray hole and a supplementary vaporization water spray hole on the wheel cover, so that the water spray amount can be flexibly adjusted to ensure that the gas humidity meets the requirements. It is suitable for variable frequency compressors, and the power saving will not decrease significantly with changes in the operating conditions of the compressor.

[0021] 2. According to the contour of the intake duct, the water spray holes near the inlet and outlet areas of the present invention are arranged with their axes perpendicular to the wall of the intake duct, so that liquid droplets can be sent into the interior of the intake duct for sufficient vaporization and cooling. The axes of the water spray holes in the middle area are nearly parallel to the wall of the intake duct, which can supplement the vaporization and cooling of the gas while suppressing leakage in the blade tip clearance, thereby improving the operating efficiency and operating range of the centrifugal compressor.

[0022] 3. The present invention sets humidity measuring points to monitor the gas humidity and realizes real-time feedback control of the water spraying amount, which can improve the control accuracy and make the relative humidity of the air always close to 100% during the compression process. The simulated power saving can reach 5%.

[0023] 4. The humidity measuring point of the present invention is arranged behind the water spraying position and is offset from the water spraying point in the circumferential direction, which can improve the accuracy of gas humidity monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0025] Figure 1 This is a schematic diagram of the compressor impeller position structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the roulette disc structure of the present invention;

[0027] Among them, 1-impeller, 2-impeller cover, 3-inlet air duct, 4-water spray hole, 5-humidity measurement point. DETAILED DESCRIPTION

[0028] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are set forth herein below. Each embodiment and example is provided by way of explanation of the apparatus, composition, and materials of the present disclosure, and is not intended to be limiting. On the contrary, the following description provides a convenient illustration of exemplary embodiments for implementing the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made within the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0029] like Figure 1 and Figure 2 As shown, a wet compression centrifugal compressor, the improvement mainly involves the improvement of the water spray structure at the compressor impeller position, so Figure 1 and Figure 2 Provides a partial view of the impeller position; includes an impeller 1 and a wheel cover 2, an inlet air duct 3 is formed between the wheel cover 2 and the impeller 1, and water spray holes 4 for spraying liquid into the inlet air duct 3 for cooling are provided on the wheel cover 2 in the direction of the air flow. The water spray holes 4 are evenly distributed along the surface of the wheel cover 2, and each water spray hole 4 is correspondingly provided with a nozzle. The nozzles are connected to the water volume server through a pipeline, and a regulating valve for controlling the water spray volume is separately connected at the connection point. The water spray volume at the water spray hole 4 is controlled by the water volume server; along The air flow direction of the intake air duct 3, the water spray hole includes a main vaporization water spray hole located near the inlet end of the intake air duct and a supplementary vaporization water spray hole located inside the main vaporization water spray hole for supplementary water spraying according to the relative humidity of the gas. The nozzle aperture of the main vaporization water spray hole is larger than the nozzle aperture of the supplementary vaporization water spray hole. The nozzle aperture of the main vaporization water spray hole is large, and larger droplets can be produced to extend into the intake air duct to fully vaporize and cool the gas. In the embodiment of the present invention, the nozzle diameter of the main vaporization water spray hole is 20 , the nozzle diameter of the vaporization water hole is 10 .

[0030] In the present invention, the axis of the water spray hole 4 located near the gas inlet and outlet ends along the gas flow direction of the inlet flow channel 3 is perpendicular to the wall of the inlet flow channel, so that the liquid droplets can penetrate into the inlet flow channel to ensure the heat exchange effect; the axis of the water spray hole 4 in the middle area is parallel to the wall of the inlet flow channel, where the curvature is large, and part of the air flow will flow out through the fitting gap between the impeller and the wheel disc, thereby affecting the efficiency of the compressor. The water spray hole of the present invention is arranged in a type parallel to the wall of the inlet flow channel, which can realize the liquid spraying to cool the gas while suppressing the leakage of the impeller blade tip gap, thereby improving the operating efficiency and operating range of the compressor.

[0031] To achieve real-time monitoring of humidity, Figure 2 As shown, the present invention provides a humidity measuring point 5 for detecting gas humidity behind the corresponding water spray hole 4 along the axial direction of the inlet air flow channel 3. The gas humidity after each water spray hole 4 sprays water is detected through the humidity measuring point 5. To improve the accuracy of the detection, the water spraying positions of the water spray holes 4 in front of the humidity measuring point 5 are staggered in the circumferential direction. The staggering angle is preferably 45°. An electronic hygrometer is installed for detection. After water spraying, the vaporized and cooled gas will flow to the area where the humidity measuring point 5 is located, thereby obtaining accurate humidity data in the vaporized gas.

[0032] The water spray holes 4 of the present invention, which are located in the same axial plane of the wheel cover 2, are arranged at 5%, 30% and 70% of the length of the intake air duct along the axial direction of the intake air duct, wherein the water spray hole at the 5% length position serves as the main vaporization water spray hole, and the water spray holes at the 30% and 70% length positions serve as supplementary vaporization water spray holes. The axis of the water spray hole at the 30% length position is parallel to the wall of the intake air duct, and the axis of the water spray hole at the 70% length position is perpendicular to the intake duct. There are 12 water spray holes in total, which are distributed at 90° intervals along the circumferential direction of the wheel cover 2. The corresponding humidity measuring points 5 are set at 15%, 45% and 85% of the length of the intake air duct axis to detect the humidity of the gas after water is sprayed from the corresponding front water spray holes.

[0033] The present invention discloses an intake air compression control method for the wet compression centrifugal compressor, comprising the steps of:

[0034] S01. Dividing the centrifugal compressor into a normal operation zone and a near-surge zone according to operating conditions, setting corresponding water spray volumes, and determining the current operating zone of the compressor based on flow and pressure parameters during operation of the centrifugal compressor;

[0035] S02. Determine the corresponding maximum total water injection flow rate based on the suction flow rate. During the initial water injection, if the centrifugal compressor is operating in the normal operating area, the maximum total water injection flow rate is set to 3% of the suction flow rate. If the centrifugal compressor is operating in the near-surge area, the maximum total water injection flow rate is set to 1% of the suction flow rate.

[0036] S03. Within a range below the maximum total water spray flow rate, the water flow rate of the nozzle is distributed through the water volume servo, and the humidity of the gas is monitored through the humidity measurement points set on the wheel cover. The water flow rate of the nozzle is adjusted according to the monitoring results to make the humidity of the gas downstream along the air intake direction close to 99%.

[0037] In step S03 of the present invention, when the water spray volume of the nozzle is adjusted according to the monitoring results of the humidity measuring point, when the average humidity value monitored by the humidity measuring point is lower than 95% or higher than 99%, the total water spray flow rate is increased or decreased accordingly to control the gas humidity so that the average humidity value is within the range of 95%-99%; when the average humidity value is within the range of 95%-99%, the flow rate of the nozzle is adjusted according to the gas humidity monitored by the humidity measuring point downstream of the inlet flow channel so that the downstream gas humidity approaches 99%. The control method of the present invention can realize the ideal wet compression process of the compressor, that is, the evaporation of the water injected during the compression process makes the relative humidity of the air during the compression process always close to 100%. After computational fluid dynamics simulation, the power saving can reach 5%, and the water spray volume at each point can be adjusted in real time. It is suitable for variable frequency compressors, and the power saving does not decrease significantly with changes in the operating conditions of the compressor, thereby ensuring efficiency.

Claims

1. A wet compression centrifugal compressor, characterized in that: The invention comprises an impeller (1) and a wheel cover (2), an inlet flow channel (3) is formed between the wheel cover (2) and the impeller (1), a water spray hole (4) for spraying liquid to cool the inlet flow channel (3) is provided on the wheel cover (2) in the direction of the inlet flow, the water spray holes (4) are evenly distributed along the surface of the wheel cover (2), a nozzle is correspondingly provided in each water spray hole (4), the nozzles are connected to the water volume servo through a pipeline, a regulating valve for controlling the water spray volume is separately connected at the connection point, and the water spray volume at the water spray hole (4) is controlled by the water volume servo; along the air flow direction of the inlet flow channel (3), the water spray hole comprises a main vaporization water spray hole located near the inlet end of the inlet flow channel and a supplementary vaporization water spray hole located inside the main vaporization water spray hole for supplementary water spray according to the relative humidity of the gas, the nozzle aperture in the main vaporization water spray hole is larger than the nozzle aperture of the supplementary vaporization water spray hole; Along the gas flow direction of the inlet flow channel (3), the axes of the water spray holes (4) located near the inlet and outlet ends of the inlet flow channel are perpendicular to the wall surface of the inlet flow channel; the axes of the water spray holes (4) located in the middle area are parallel to the wall surface of the inlet flow channel, spraying liquid to cool the gas while suppressing leakage from the impeller tip clearance; A humidity measuring point (5) for detecting gas humidity is provided behind the corresponding water spray hole (4) along the axial direction of the inlet air flow channel (3).

2. A wet compression centrifugal compressor according to claim 1, characterized in that: The water spray holes (4) located in the same axial plane of the wheel cover (2) are arranged at 5%, 30% and 70% length positions of the intake air duct along the axial direction of the intake air duct, wherein the water spray hole at the 5% length position serves as a main vaporization water spray hole, and the water spray holes at the 30% and 70% length positions serve as supplementary vaporization water spray holes.

3. A wet compression centrifugal compressor according to claim 2, characterized in that: The humidity measuring points (5) are arranged at 15%, 45% and 85% length positions of the intake air duct axis.

4. A wet compression centrifugal compressor according to claim 2, characterized in that: The water spraying positions of the water spraying holes (4) in front of the humidity measuring point (5) corresponding to the position are staggered in the circumferential direction.

5. A wet compression centrifugal compressor according to claim 2, characterized in that: The axis of the water spray hole at the 30% length position is parallel to the wall surface of the intake air duct, and the axis of the water spray hole at the 70% length position is perpendicular to the wall surface of the intake air duct.

6. A method for controlling intake air compression of a wet compression centrifugal compressor according to any one of claims 1 to 5, characterized in that: Including steps: S01. Dividing the centrifugal compressor into a normal operation zone and a near-surge zone according to operating conditions, setting corresponding water spray volumes, and determining the current operating zone of the compressor based on flow and pressure parameters during operation of the centrifugal compressor; S02. Determine the corresponding maximum total water spray flow rate according to the suction flow rate; S03. Within a range below the maximum total water spray flow rate, the water flow rate of the nozzle is distributed through the water volume servo, and the humidity of the gas is monitored through the humidity measurement points set on the wheel cover. The water flow rate of the nozzle is adjusted according to the monitoring results to make the humidity of the gas downstream along the air intake direction close to 99%.

7. The method for controlling intake air compression of a wet compression centrifugal compressor according to claim 6, characterized in that: In step S02, when water spraying is initially performed, if the operating area of ​​the centrifugal compressor is in the normal operating area, the maximum total water spray flow rate is set to 3% of the suction flow rate; if the operating area of ​​the centrifugal compressor is in the near-surge area, the maximum total water spray flow rate is set to 1% of the suction flow rate.

8. The method for controlling intake air compression of a wet compression centrifugal compressor according to claim 6, wherein: In step S03, when the water spraying amount of the nozzle is adjusted according to the monitoring results of the humidity measuring point, when the average relative humidity monitored by the humidity measuring point is lower than 95% or higher than 99%, the total water spraying flow rate is increased or decreased accordingly, and the gas humidity is controlled so that the average humidity value is in the range of 95%-99%; when the average humidity value is in the range of 95%-99%, the flow rate of the nozzle is adjusted according to the gas humidity monitored by the humidity measuring point downstream of the inlet flow duct, so that the downstream gas humidity approaches 99%.

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