Internal flow jet cooling device and cooling method for centrifugal compressor

Abstract

The invention discloses an internal flow jet cooling device and method for a centrifugal compressor, and solves the problems that in the prior art, temperature rise cannot be directly restrained in real time in the compression process to solve the fundamental overtemperature problem, or equipment damage, efficiency reduction and applicability limitation are caused when cooling is introduced. A cooling point is arranged in the middle of an internal flow channel of the centrifugal impeller, a mainstream working medium at the position is partially compressed and has enough degree of superheat, and a sprayed refrigerant can immediately evaporate and absorb heat and directly take away the compressed heat, so that on one hand, the erosive wear of a blade material caused by liquid drops is effectively reduced, and the service life of the impeller is remarkably prolonged; and on the other hand, impact and disturbance on the main air flow state are reduced, the stability of a flow field can be kept, accordingly, pneumatic losses are reduced, and the efficiency of the compressor is improved.

Description

Technical Field

[0001] This invention relates to the field of centrifugal compressor technology, specifically to an internal jet cooling device and cooling method for a centrifugal compressor. Background Technology

[0002] Centrifugal compressors are key power equipment widely used in industrial fields, commonly found in air compression, refrigeration cycles, high-temperature heat pumps, and process gas pressurization. Their working principle dictates that the working fluid experiences a significant temperature rise during compression, a phenomenon particularly pronounced in applications requiring high compression ratios or high exhaust temperatures. Excessive temperatures not only increase compression power consumption and reduce system efficiency but also threaten safe operation: for example, causing rotating components such as impellers to fail due to reduced material strength, or leading to the decomposition and degradation of organic working fluids and lubricating oils. Therefore, effective cooling of the working fluid during compression is a crucial technical requirement for ensuring the efficient, reliable, and long-life operation of centrifugal compressors.

[0003] To address the above problems, existing technologies mainly employ the following two cooling methods: First, there's pre-cooling and interstage cooling. This involves installing heat exchangers at the compressor inlet or between stages in multi-stage compression to cool the working fluid. While this method reduces inlet or interstage temperatures, it's essentially a sequential process of "cooling before compression" or "compression, cooling, then compression." The cooling effect occurs outside or after the compression stage and cannot directly intervene in the compression thermodynamics within the impeller. When the single-stage compression ratio is extremely high or the operating temperature range is extremely high, the working fluid temperature within the impeller and flow channels may still rise to dangerous levels, and the risk of overheating cannot be eliminated. Furthermore, the added heat exchanger introduces additional flow resistance, leading to pressure loss and imposing stringent requirements on the system's total pressure recovery coefficient, potentially offsetting some energy-saving benefits.

[0004] Secondly, there is intake spray cooling. Commonly used in gas turbine intake systems, this method involves spraying atomized liquid droplets into the intake pipe, utilizing their evaporation and heat absorption to lower the intake air temperature. However, this method has significant limitations: First, to prevent unevaporated droplets from impacting and eroding the downstream high-speed rotating impeller, strict limitations are placed on the spray particle size, evaporation distance, and air humidity, restricting cooling capacity and applicability. Second, for many compressor applications, the inlet working fluid is already near saturation; excessive spray volume can lead to premature liquid phase formation, potentially causing liquid slugging and endangering compressor safety. More importantly, the nozzles of traditional spray devices are fixed to a stationary casing, resulting in a significant relative velocity between the sprayed droplets and the high-speed rotating impeller. This not only causes severe impact erosion of the blades, significantly shortening impeller life, but also severely disrupts the uniformity and stability of the main intake airflow, leading to additional aerodynamic losses and affecting compressor efficiency and operational stability. Summary of the Invention

[0005] The purpose of this invention is to provide an internal jet cooling device and cooling method for a centrifugal compressor, in order to solve the problems mentioned in the background art, such as either being unable to suppress temperature rise in real time and directly during the compression process to solve the fundamental overheating problem, or causing equipment damage, efficiency reduction and limited applicability when introducing cooling.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an internal jet cooling device for a centrifugal compressor, comprising: Centrifugal impeller, its impeller back and blades form the main working fluid channel; A rotating shaft is fixedly connected coaxially to the centrifugal impeller; The refrigerant injection unit includes a stationary refrigerant inlet pipe and an injection pipe, used to introduce refrigerant into the interior of the rotating component; A storage chamber, located inside the hub of the rotating shaft and / or centrifugal impeller, and in fluid communication with the injection pipe, is used to contain refrigerant; A perforated chuck is provided at the front end or inside of the centrifugal impeller; At least one outflow hole is provided on the perforated chuck, connecting the storage cavity with the main working fluid channel; The outlet hole is located in the middle section of the mainstream working fluid channel. When the rotating shaft drives the centrifugal impeller to rotate, the refrigerant is injected from the storage chamber into the mainstream working fluid through the outlet hole under the action of centrifugal force, so as to achieve compression and cooling at the same time.

[0007] Preferably, the diameter of the outflow hole is less than or equal to 1 mm.

[0008] Preferably, the storage cavity is provided with a porous structure for uniform distribution of refrigerant.

[0009] More preferably, the outlet structure of the outflow hole is a flared opening, a porous structure, or a porous coating, to promote uniform mixing of the refrigerant and the mainstream working fluid.

[0010] More preferably, the outlet hole is inclined axially or in the opposite circumferential direction to reduce interference with the mainstream airflow.

[0011] One type of centrifugal compressor includes an internal jet cooling device.

[0012] A centrifugal compressor internal jet cooling method includes the following steps: The refrigerant is introduced into the storage chamber inside the high-speed rotating component through a stationary refrigerant injection unit; The centrifugal force generated by the high-speed rotation of the rotating component drives the refrigerant in the storage chamber to be ejected from the outflow hole located in the middle section of the main working fluid channel; The injected refrigerant mixes directly with the mainstream working fluid being compressed within the centrifugal impeller channel, absorbing the heat of compression and achieving simultaneous compression and cooling of the working fluid.

[0013] Preferably, the refrigerant is a liquid working fluid.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. The centrifugal compressor internal flow jet cooling device and cooling method sets the cooling point in the middle of the internal flow channel of the centrifugal impeller. At this position, the mainstream working fluid has been partially compressed and has sufficient superheat. The injected refrigerant can immediately evaporate and absorb heat, directly carrying away the compressed heat.

[0015] 2. The centrifugal compressor internal flow jet cooling device and cooling method, since the refrigerant is ejected from an open chuck that rotates at high speed synchronously with the impeller, the circumferential velocity of the ejected droplets is very close to the gas velocity in the impeller flow channel, which greatly reduces the relative velocity between the droplets and the impeller blades. On the one hand, this effectively reduces the erosion and wear of the blade material by the droplets and significantly extends the service life of the impeller; on the other hand, it reduces the impact and disturbance on the main airflow, which is conducive to maintaining the stability of the flow field, thereby reducing aerodynamic losses and improving the efficiency of the compressor. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the internal flow jet cooling structure of the perforated chuck of the centrifugal compressor of the present invention; Figure 2 This is a schematic diagram of the perforated chuck structure of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of the refrigerant inlet pipe of the present invention.

[0017] In the diagram: 101, refrigerant inlet pipe; 102, injection pipe; 103, storage chamber; 104, outlet hole; 105, perforated chuck; 201, centrifugal impeller blade; 202, centrifugal impeller back; 301, rotating shaft; 401, casing. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Refer to Figure 1-3 This embodiment provides an internal jet cooling device for a centrifugal compressor. This device is mainly used in centrifugal refrigerant compressors of high-temperature heat pumps to solve the problem of excessively high refrigerant temperature during compression.

[0020] The device includes a rotating shaft 301, a centrifugal impeller, an orifice chuck 105, and a stationary injection pipe 102.

[0021] The rotating shaft 301 has an axially extending refrigerant channel machined inside. The centrifugal impeller is fixed to the rotating shaft 301 by means of interference fit or key connection, and rotates at high speed with the shaft. The centrifugal impeller is composed of a wheel back 202 and multiple blades 201. The blades 201 and the wheel back 202 together form an impeller flow channel that expands from the center to the outer periphery.

[0022] The perforated chuck 105 is bolted to the front end of the centrifugal impeller and connected to the front end of the rotating shaft 301 to ensure synchronous rotation with the centrifugal impeller. An annular storage cavity 103 is machined inside the perforated chuck 105. The refrigerant channel outlet at the front end of the rotating shaft 301 communicates with the storage cavity 103. Multiple tiny outflow holes 104 are uniformly machined circumferentially on the radially outer side wall of the perforated chuck 105. The outlets of these outflow holes 104 are precisely located in the middle of the impeller flow channel to prevent excessive coolant spraying.

[0023] One end of the stationary injection pipe 102 is connected to the external refrigerant inlet pipe 101 via a flange, while the other end, a slender portion, extends into the refrigerant channel inlet at the rear end of the rotating shaft 301. The outer diameter of the injection pipe 102 is slightly smaller than the diameter of the channel inside the rotating shaft 301, forming an annular gap between them. Due to the centrifugal force creating a negative pressure in the storage chamber 103 that is much lower than the inlet pressure, coupled with the effect of liquid surface tension, the refrigerant will not flow out from this gap, thus affecting the operation of the impeller inlet.

[0024] The working process of this embodiment is as follows: The compressor starts, and the rotating shaft 301 drives the centrifugal impeller and the perforated chuck 105 to rotate at high speed. The liquid refrigerant provided by the external cooling system enters the refrigerant channel of the rotating shaft 301 through the refrigerant inlet pipe 101 and the injection pipe 102. Under the action of strong centrifugal force, the refrigerant is pressed towards the outer periphery of the rotating shaft and enters the storage chamber 103 of the perforated chuck 105 through the channel. Driven by the pressure difference generated by centrifugal force, the refrigerant in the storage chamber 103 is thrown out at high speed from the outlet hole 104, forming an atomized or fine jet. Since the outlet hole 104 is located in the middle of the impeller flow channel, the mainstream working fluid has been partially compressed and has sufficient superheat. The injected liquid refrigerant evaporates and absorbs heat rapidly, and mixes thoroughly with the mainstream working fluid, achieving the effect of "compression and cooling at the same time". This process directly removes the heat of compression and effectively controls the temperature rise of the impeller and the working fluid. At the same time, the circumferential velocity of the sprayed refrigerant droplets is close to that of the impeller, reducing the impact on the blades and the disturbance of the airflow. During the operation of the embodiment, centrifugal force creates a radial pressure difference within the refrigerant, from the center of rotation to the outlet. Assuming the impeller's operating speed is... N The density is... ρ l The location of the outlet hole is r 0 Then the pressure difference generated by centrifugal force is: ; Taking water spray cooling as an example, the density of water is 1000 kg / m³. 3 If the outlet is set at r 0 =50 At [mm], when the rotational speed is N At 30,000 rpm, the pressure difference between the shaft center and the outlet orifice is as high as =12.32MPa, which is not only far higher than the resistance that the liquid needs to overcome to flow through the internal channel, but also higher than the pressure of the mainstream medium.

[0025] Example 2: Based on Example 1, this example further optimizes the refrigerant outflow characteristics. Specifically, the storage cavity 103 of the perforated chuck 105 is filled with a porous metal fiber material. This porous structure helps to make the refrigerant distribution in the storage cavity 103 more uniform under high-speed rotation conditions, reducing the imbalance problem that may be caused by uneven liquid distribution during high-speed rotation. At the same time, the porous material has a certain damping and distribution effect on the refrigerant flow, which can make the refrigerant flow more smoothly to each outflow hole 104.

[0026] Example 3: Based on Example 1, this example improves the structure of the outflow hole 104. The outlet section of the outflow hole 104 is machined into an outwardly expanding funnel shape. This structure can reduce the flow velocity of the refrigerant when it flows out, making it easier to adhere to the flow channel wall and promoting its smooth mixing with the mainstream gas, thus avoiding the formation of excessively large droplets that impact the downstream blades.

[0027] Example 4: Based on Example 1, this example changes the opening direction of the outlet orifice 104. The central axis of the outlet orifice 104 is not strictly radial, but designed to have an anti-circumferential tilt angle opposite to the impeller rotation direction. This design can reduce the relative velocity difference and interference intensity between the refrigerant jet and the high-speed circumferentially flowing mainstream gas, further reducing aerodynamic losses.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A centrifugal compressor internal jet cooling device, characterized in that, include: The centrifugal impeller (202) has its back and blades (201) forming a mainstream working fluid channel; The rotating shaft (301) is coaxially and fixedly connected to the centrifugal impeller (202); The refrigerant injection unit includes a stationary refrigerant inlet pipe (101) and an injection pipe (102) for introducing refrigerant into the interior of the rotating component; The storage chamber (103) is disposed inside the hub of the rotating shaft (301) and / or the centrifugal impeller (202), and is in fluid communication with the injection pipe (102) for containing refrigerant; A perforated chuck (105) is disposed at the front end or inside the centrifugal impeller (202); At least one outlet hole (104) is provided on the perforated chuck (105) and connects the storage cavity (103) with the main working fluid channel; The outlet hole (104) is located in the middle section of the main working medium channel. When the rotating shaft (301) drives the centrifugal impeller (202) to rotate, the refrigerant is injected from the storage chamber (103) into the main working medium through the outlet hole (104) under the action of centrifugal force, so as to achieve compression and cooling at the same time.

2. The centrifugal compressor internal jet cooling device according to claim 1, characterized in that, The diameter of the outflow hole (104) is less than or equal to 1 mm.

3. The centrifugal compressor internal jet cooling device according to claim 1 or 2, characterized in that, The storage cavity (103) is provided with a porous structure for uniform distribution of refrigerant.

4. The centrifugal compressor internal jet cooling device according to claim 1 or 2, characterized in that, The outlet structure of the outflow hole (104) is a flared mouth, a porous structure, or a porous coating, to promote uniform mixing of the refrigerant and the mainstream working fluid.

5. The centrifugal compressor internal jet cooling device according to claim 1 or 2, characterized in that, The outlet hole (104) is inclined axially or in reverse circumferentially to reduce interference with the mainstream airflow.

6. A centrifugal compressor, characterized in that, It includes an internal jet cooling device for a centrifugal compressor as described in any one of claims 1 to 5.

7. A method for internal jet cooling of a centrifugal compressor, characterized in that, The device applied to any one of claims 1 to 5 includes the following steps: The refrigerant is introduced into the storage chamber (103) inside the high-speed rotating component through a stationary refrigerant injection unit. Using the centrifugal force generated by the high-speed rotation of the rotating component, the refrigerant in the storage chamber (103) is driven to be ejected from the outlet (104) located in the middle section of the main working fluid channel; The injected refrigerant mixes directly with the mainstream working fluid being compressed within the centrifugal impeller channel, absorbing the heat of compression and achieving simultaneous compression and cooling of the working fluid.

8. The centrifugal compressor internal jet cooling method according to claim 7, characterized in that: The refrigerant is a liquid working fluid.

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