Impeller for improving axial stress of CO2 centrifugal compressor and size calculation method of impeller

Abstract

The invention discloses an impeller for improving axial stress of a CO2 centrifugal compressor and a size calculation method of the impeller, relates to a centrifugal compressor impeller and a size calculation method of the impeller, and aims to solve the problem that the CO2 centrifugal compressor is poor in safety and stability due to the fact that axial stress of an existing CO2 centrifugal compressor impeller is completely borne by fastening bolts. A sealing shaft sleeve is arranged outside a rotating shaft, and an annular boss on the back of a centrifugal impeller and the sealing shaft sleeve are pressed tightly through a fastening bolt; wherein the annular boss on the back of the centrifugal impeller disc, the annular sealing ring, the sealing shaft sleeve and the rotating shaft form a sealing structure; torque is transmitted between the centrifugal impeller and the rotating shaft through a spline. The CO2 centrifugal compressor has the beneficial effects that the axial stress direction of the centrifugal impeller is changed from the loosening direction to the pressing direction, the load of the fastening bolt is effectively reduced, the risk of fatigue failure of the bolt is avoided, and the safety and stability of the CO2 centrifugal compressor are improved.

Description

Technical Field

[0001] The invention relates to a centrifugal compressor impeller and a method for calculating its size. Background Art

[0002] As an important fluid machinery, CO2 centrifugal compressor has been widely used in supercritical CO2 power generation, compressed CO2 energy storage and other fields. Its main function is to perform work on CO2 gas through high-speed rotating impellers, increasing the pressure and temperature of the gas, thereby meeting the needs of different process flows. However, in actual operation, due to the high outlet pressure of the working fluid (≥20MPa), the axial force on the back of the centrifugal impeller is greater than that on the front. Under extreme working conditions, the axial force on the centrifugal impeller exceeds 30kN, and the direction of the axial force points to the direction of loosening of the impeller and the rotating shaft. Such a huge axial force is borne entirely by the fastening bolts, which brings huge challenges to the safe operation of the CO2 centrifugal compressor.

[0003] At present, although certain progress has been made in the design and manufacturing of centrifugal compressors, there is still a lack of effective solutions to the problem of excessive axial force on the impeller of CO2 centrifugal compressors. The existing centrifugal compressor impeller structure design is usually not specifically optimized for axial force, resulting in serious impact on the connection reliability between the impeller and the rotating shaft under high-pressure conditions, and the fastening bolts are prone to fatigue failure and other problems, which in turn affects the normal operation of the entire compressor and may even cause serious safety accidents.

[0004] Furthermore, with the expansion of CO2 centrifugal compressor applications in more fields and the increasing demands for compressor performance and safety, effectively improving the axial stress on the impeller has become a pressing technical challenge. This not only impacts the compressor's operating efficiency and service life, but also directly affects the equipment's safety and reliability. Therefore, developing a back structure and sizing method that can effectively improve the axial stress on the CO2 centrifugal compressor impeller has important practical significance and broad application prospects. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that the axial force of the impeller of the existing CO2 centrifugal compressor is entirely borne by the fastening bolts, resulting in poor safety and stability of the CO2 centrifugal compressor. An impeller that improves the axial force of the CO2 centrifugal compressor and a method for calculating its size are proposed.

[0006] The impeller for improving the axial force of a CO2 centrifugal compressor according to the present invention comprises a fastening bolt, a centrifugal impeller, a sealing sleeve and a rotating shaft;

[0007] The sealing sleeve is coaxially sleeved on the outside of the rotating shaft, and an annular groove is provided on the contact side of the sealing sleeve and the centrifugal impeller. An annular boss is provided on the back of the centrifugal impeller disc, and the annular boss on the back of the centrifugal impeller is pressed into the annular groove of the sealing sleeve by fastening bolts; wherein, the annular boss on the back of the centrifugal impeller disc, the sealing sleeve and the rotating shaft constitute a sealing structure; and torque is transmitted between the centrifugal impeller and the rotating shaft through a spline.

[0008] Furthermore, it also includes an annular sealing ring;

[0009] The annular sealing ring is arranged in the annular groove of the sealing sleeve.

[0010] Furthermore, a plurality of groups of balancing holes are provided on the front side wall of the centrifugal impeller disc at equal spans along its circumference.

[0011] Furthermore, the number of groups of balancing holes is four, and the inner diameter of each group of balancing holes is 2.0 mm.

[0012] A method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor comprises the following steps:

[0013] According to the inner diameter R of the centrifugal impeller 1h , Centrifugal impeller inlet rim radius R 1t , centrifugal impeller mass flow Q, centrifugal impeller inlet axial velocity C1 and inlet static pressure P1, calculate the centrifugal impeller front inner hole radius R 1h The radius R of the centrifugal impeller inlet rim 1t Axial force F0 within the range;

[0014] According to the centrifugal impeller inlet rim radius R 1t , centrifugal impeller outlet radius R2, inlet static pressure P1 and outlet static pressure P2, calculate the centrifugal impeller front inlet rim radius R 1t The axial force F1 within the radius R2 of the centrifugal impeller outlet;

[0015] According to the centrifugal impeller outlet static pressure P2, centrifugal impeller outlet radius R2, centrifugal impeller outlet density ρ, centrifugal impeller rotation speed ω and the sealing radius R of the annular boss 6 on the back of the centrifugal impeller m , calculate the sealing radius R of the annular boss on the back of the centrifugal impeller m The axial force F2 within the radius R2 of the centrifugal impeller outlet;

[0016] According to the centrifugal impeller inlet static pressure P1, centrifugal impeller inner hole radius R 1h And the sealing radius R of the annular boss on the back of the centrifugal impeller m , calculate the sealing radius R of the annular boss on the back of the centrifugal impeller m and the inner diameter R of the centrifugal impeller 1hAxial force F3 within the range;

[0017] And by adjusting the sealing radius R of the annular boss on the back of the centrifugal impeller m , change the axial force F2 and the axial force F3 so that (F0+F1)-(F2+F3)≥1kN, and then solve the sealing radius R of the annular boss on the back of the centrifugal impeller m The minimum value of .

[0018] Furthermore, the calculation formula of the axial force F0 is:

[0019]

[0020] Furthermore, the calculation formula of the axial force F1 is:

[0021]

[0022] Furthermore, the calculation formula of the axial force F2 is:

[0023]

[0024] Furthermore, the calculation formula of the axial force F3 is:

[0025]

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] Taking a single-stage supercritical CO2 centrifugal compressor as an example, the mass flow rate at the strength operating point is 12.0kg / s, the static pressure at the centrifugal impeller inlet P1=7.76MPa, the static pressure at the centrifugal impeller outlet is 17.05MPa, the static temperature at the centrifugal impeller outlet is 72.7℃, the centrifugal impeller inlet rim radius R1t=20.00mm, and the centrifugal impeller outlet radius R2=48.00mm; before improvement, the centrifugal impeller was subjected to an axial force of -30.15kN, pointing to the direction of loosening of the centrifugal impeller and the rotating shaft; after applying the impeller for improving the axial force of the CO2 centrifugal compressor described in the present invention, the centrifugal impeller was subjected to an axial force of +1.28kN, that is, by setting a sealing structure on the back of the centrifugal impeller to change the axial force direction of the centrifugal impeller from the loosening direction to the tightening direction, the stress state of the fastening bolts is greatly improved, the load of the fastening bolts is effectively reduced, the risk of fatigue failure of the bolts is avoided, and the safety and stability of the CO2 centrifugal compressor are improved; and by adjusting the sealing radius R of the annular boss on the back of the centrifugal impeller m , change the axial force, and calculate the sealing radius R by a clear calculation method m The minimum value improves design efficiency and accuracy, making it easier for engineering technicians to design quickly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic cross-sectional view of an impeller for improving the axial force of a CO2 centrifugal compressor according to the first embodiment;

[0029] Figure 2 for Figure 1 Schematic diagram of the enlarged structure at position Ⅰ;

[0030] Figure 3 for Figure 1 Schematic diagram of the enlarged structure at point II;

[0031] Figure 4 This is a schematic diagram of the radial dimensions of the CO2 centrifugal compressor impeller in the fifth embodiment;

[0032] Figure 5 This is a schematic diagram of the axial force on the impeller of the CO2 centrifugal compressor in the fifth embodiment. DETAILED DESCRIPTION

[0033] Specific implementation method 1. Combination Figures 1 to 3 To illustrate this embodiment, an impeller for improving the axial force of a CO2 centrifugal compressor according to this embodiment includes a fastening bolt 1, a centrifugal impeller 2, a sealing sleeve 3 and a rotating shaft 4;

[0034] The sealing sleeve 3 is coaxially sleeved on the outside of the rotating shaft 4, and an annular groove is provided on the contact side of the sealing sleeve 3 and the centrifugal impeller 2. An annular boss 6 is provided on the back of the impeller disk of the centrifugal impeller 2, and the annular boss 6 on the back of the impeller disk of the centrifugal impeller 2 is pressed into the annular groove of the sealing sleeve 3 by the fastening bolt 1; wherein, the annular boss 6 on the back of the impeller disk of the centrifugal impeller 2, the sealing sleeve 3 and the rotating shaft 4 constitute a sealing structure; and torque is transmitted between the centrifugal impeller 2 and the rotating shaft 4 through a spline.

[0035] In this embodiment, the dual connection method of fastening bolts 1 and splines is used to effectively improve the connection strength and reliability between the centrifugal impeller 2 and the rotating shaft 4, thereby avoiding the risk of the impeller loosening under high-pressure conditions and improving the safety and stability of the CO2 centrifugal compressor. In addition, the fastening bolts 1 and spline connection method have a simple structure, are easy to assemble and disassemble, and reduce manufacturing and maintenance costs.

[0036] Specific embodiment 2: This embodiment further defines the impeller for improving the axial force of the CO2 centrifugal compressor described in specific embodiment 1. In this embodiment, it further includes an annular sealing ring 5;

[0037] The annular sealing ring 5 is arranged in the annular groove of the sealing sleeve 3 .

[0038] In this embodiment, through the press fit between the annular sealing ring 5 and the annular boss 6 on the back of the centrifugal impeller 2, the annular sealing ring 5 is deformed to form a sealing surface, which effectively prevents the leakage of high-pressure CO2 gas and improves the sealing performance of the compressor; through the press fit between the annular sealing ring 5 and the annular boss 6, the pressure distribution on the back of the centrifugal impeller 2 is changed, thereby improving the axial force condition of the centrifugal impeller 2 and reducing the load of the fastening bolt 1.

[0039] Specific embodiment three: This embodiment further limits the impeller for improving the axial force of a CO2 centrifugal compressor described in specific embodiment two. In this embodiment, a plurality of groups of balancing holes 7 are provided on the front side wall of the impeller disc of the centrifugal impeller 2 at equal spans along its circumference.

[0040] In this embodiment, the static pressure within the radius of the annular boss 6 on the back of the centrifugal impeller 2 is kept consistent with the static pressure at the inlet of the centrifugal impeller 2 through the balancing hole 7, effectively balancing the pressure distribution on the back of the impeller, and further improving the axial force condition of the centrifugal impeller 2; at the same time, the setting of the balancing hole 7 reduces the pressure fluctuation on the back of the centrifugal impeller 2, reduces vibration and noise, and improves the operating stability and reliability of the compressor.

[0041] Specific embodiment 4. This embodiment further limits the impeller for improving the axial force of a CO2 centrifugal compressor described in specific embodiment 3. In this embodiment, the number of groups of balancing holes 7 is four, and the inner diameter of each group of balancing holes 7 is 2.0 mm.

[0042] In this embodiment, by clarifying the number and size of the balancing holes, the accuracy and stability of the pressure balance on the back of the centrifugal impeller 2 are ensured, and the axial force condition is further optimized; clear size and quantity requirements facilitate processing and quality control, and reduce production costs.

[0043] Specific implementation method 5. Combination Figures 4 and 5 This embodiment describes a method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor according to the third embodiment, which includes the following steps:

[0044] According to the inner hole radius R of the centrifugal impeller 2 1h , Centrifugal impeller 2 inlet rim radius R 1t , the mass flow rate Q of centrifugal impeller 2, the axial velocity C1 and the static pressure P1 of the inlet of centrifugal impeller 2, calculate the radius R of the inner hole at the front of centrifugal impeller 2 1h The radius R of the inlet rim of the centrifugal impeller 2 1t Axial force F0 within the range;

[0045] According to the inlet rim radius R of the centrifugal impeller 2 1t, centrifugal impeller 2 outlet radius R2, inlet static pressure P1 and outlet static pressure P2, calculate the centrifugal impeller 2 front inlet rim radius R 1t The axial force F1 within the radius R2 of the centrifugal impeller 2;

[0046] According to the static pressure P2 at the outlet of the centrifugal impeller 2, the radius R2 at the outlet of the centrifugal impeller 2, the density ρ at the outlet of the centrifugal impeller 2, the rotation speed ω of the centrifugal impeller 2 and the sealing radius R of the annular boss 6 at the back of the centrifugal impeller 2 m , calculate the sealing radius R of the annular boss 6 on the back of the centrifugal impeller 2 m The axial force F2 within the radius R2 of the centrifugal impeller 2;

[0047] According to the static pressure P1 at the inlet of the centrifugal impeller 2 and the inner hole radius R of the centrifugal impeller 2 1h And the sealing radius R of the annular boss 6 on the back of the centrifugal impeller 2 m , calculate the sealing radius R of the annular boss 6 on the back of the centrifugal impeller 2 m The inner diameter R of the centrifugal impeller 2 1h Axial force F3 within the range;

[0048] By adjusting the sealing radius R of the annular boss 6 on the back of the centrifugal impeller 2 m , change the axial force F2 and the axial force F3 so that (F0+F1)-(F2+F3)≥1kN, and then solve the sealing radius R of the annular boss 6 on the back of the centrifugal impeller 2 m The minimum value of .

[0049] In this embodiment, the inner diameter R of the centrifugal impeller 2 is 1h , Centrifugal impeller 2 inlet rim radius R 1t , the inlet static pressure P1 of the centrifugal impeller 2, the inlet axial velocity C1 of the centrifugal impeller 2, the mass flow rate Q of the centrifugal impeller (2), the outlet static pressure P2 of the centrifugal impeller 2, the outlet radius R2 of the centrifugal impeller 2, the outlet density ρ of the centrifugal impeller 2 and the rotational speed ω of the centrifugal impeller 2 are all given input data; the sealing radius R m For adjustable data;

[0050] Through clear calculation steps and formulas, the minimum sealing radius of the annular boss 6 on the back of the centrifugal impeller 2 can be accurately calculated, ensuring the effective improvement of the axial force of the centrifugal impeller 2; and it is clear that the core of the size calculation method of the impeller to improve the axial force of the CO2 centrifugal compressor is to calculate the minimum sealing radius R at the annular boss 6 on the back of the centrifugal impeller 2 m ; The minimum sealing radius R obtained m When the number is a decimal, it is rounded up to 0.00mm / 0.25mm / 0.50mm / 0.75mm.

[0051] Specific embodiment 6: This embodiment further limits the method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor described in specific embodiment 5. In this embodiment, the calculation formula of the axial force F0 is:

[0052]

[0053] In this embodiment, the axial force at the front of the centrifugal impeller 2 can be accurately calculated through a clear formula, providing reliable data support for the subsequent structural design and optimization of the centrifugal impeller 2; the formula is simple and clear, easy to understand and apply, and improves design efficiency.

[0054] Specific embodiment 7: This embodiment further limits the method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor described in specific embodiment 6. In this embodiment, the calculation formula of the axial force F1 is:

[0055]

[0056] In this embodiment, the calculation formula of the axial force F1 is derived by determining the distribution law P1(R) of the static pressure at the front of the centrifugal impeller with the radius R;

[0057] The calculation formula of the static pressure distribution law P1(R) at the front of the centrifugal impeller with radius R is:

[0058]

[0059] Among them, R is the radius independent variable;

[0060] Then, the calculation formula of the axial force F1 is derived as follows:

[0061]

[0062] Through a clear formula for static pressure distribution, the pressure distribution in front of the centrifugal impeller 2 can be accurately described, providing a basis for accurate calculation of the axial force; through precise formula calculation, the axial force condition of the centrifugal impeller 2 can be more accurately predicted, and the impeller structure design can be further optimized.

[0063] Specific embodiment 8. This embodiment further limits the method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor described in specific embodiment 7. In this embodiment, the calculation formula of the axial force F2 is:

[0064]

[0065] In this embodiment, the calculation formula of the axial force F2 is derived by determining the calculation formula of the distribution law P2(R) of the static pressure at the back of the centrifugal impeller 2 with the radius R; and the calculation formula of the distribution law P2(R) of the static pressure at the back of the centrifugal impeller 2 with the radius R is determined by using the derivative of the static pressure P2(R) at the back of the centrifugal impeller 2 with respect to the radius R;

[0066] Among them, the specific formula for the derivative of the static pressure P2(R) on the back of the centrifugal impeller 2 with respect to the radius R is:

[0067]

[0068] Integrating the above formula, the distribution law of the static pressure P2(R) on the back of the centrifugal impeller is:

[0069]

[0070] It can be deduced that the calculation formula of the axial force F2 is:

[0071]

[0072] Through a clear formula for static pressure distribution, the pressure distribution on the back of the centrifugal impeller 2 can be accurately described, providing a basis for the accurate calculation of the axial force; by accurately calculating the back axial force, the structural design of the back of the centrifugal impeller 2 can be better optimized, and the axial force condition can be further improved.

[0073] Specific embodiment 9. This embodiment further limits the method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor described in specific embodiment 8. In this embodiment, the calculation formula of the axial force F3 is:

[0074]

[0075] In this embodiment, due to the existence of the balancing holes 7, the sealing radius R of the annular boss 6 on the back of the centrifugal impeller 2 is m The inner diameter R of the centrifugal impeller 2 1h The static pressure within the range is equal to the static pressure P1 at the centrifugal impeller inlet; thus, the calculation formula of the axial force F3 is obtained; and through comprehensive and accurate calculation, the centrifugal impeller 2 structure that meets the working conditions can be designed more reliably, thereby improving the safety and stability of the compressor.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An impeller for improving the axial force of a CO2 centrifugal compressor, characterized in that: It comprises a fastening bolt (1), a centrifugal impeller (2), a sealing sleeve (3) and a rotating shaft (4); The sealing sleeve (3) is coaxially sleeved on the outside of the rotating shaft (4), and an annular groove is provided on the contact side of the sealing sleeve (3) and the centrifugal impeller (2). An annular boss (6) is provided on the back of the centrifugal impeller (2) wheel disc, and the annular boss (6) on the back of the centrifugal impeller (2) is pressed into the annular groove of the sealing sleeve (3) by fastening bolts (1); wherein the annular boss (6) on the back of the centrifugal impeller (2) wheel disc, the sealing sleeve (3) and the rotating shaft (4) constitute a sealing structure; and torque is transmitted between the centrifugal impeller (2) and the rotating shaft (4) via a spline.

2. The impeller for improving the axial force of a CO2 centrifugal compressor according to claim 1, characterized in that: Also includes an annular sealing ring (5); The annular sealing ring (5) is arranged in the annular groove of the sealing sleeve (3).

3. The impeller for improving the axial force of a CO2 centrifugal compressor according to claim 2, characterized in that: A plurality of groups of balancing holes (7) are provided on the front side wall of the wheel disc of the centrifugal impeller (2) at equal spans along the circumference thereof.

4. The impeller for improving the axial force of a CO2 centrifugal compressor according to claim 3, characterized in that: The number of groups of the balancing holes (7) is four, and the inner diameter of each group of balancing holes (7) is 2.0 mm.

5. A method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor according to claim 3, characterized in that: The following steps are involved: According to the inner diameter R of the centrifugal impeller (2) 1h 、Centrifugal impeller (2) inlet rim radius R 1t , the mass flow rate Q of the centrifugal impeller (2), the axial velocity C1 at the inlet of the centrifugal impeller (2) and the static pressure P1 at the inlet, calculate the radius R of the inner hole at the front of the centrifugal impeller (2) 1h The radius R of the inlet rim of the centrifugal impeller (2) 1t Axial force F0 within the range; According to the inlet rim radius R of the centrifugal impeller (2) 1t , centrifugal impeller (2) outlet radius R2, inlet static pressure P1 and outlet static pressure P2, calculate the centrifugal impeller (2) front inlet rim radius R 1t An axial force F1 within the radius R2 of the centrifugal impeller (2); According to the static pressure P2 at the outlet of the centrifugal impeller (2), the radius R2 at the outlet of the centrifugal impeller (2), the density ρ at the outlet of the centrifugal impeller (2), the rotation speed ω of the centrifugal impeller (2) and the sealing radius R of the annular boss (6) at the back of the centrifugal impeller (2) m Calculate the sealing radius R of the annular boss (6) on the back of the centrifugal impeller (2) m An axial force F2 within the radius R2 of the centrifugal impeller (2); According to the static pressure P1 at the inlet of the centrifugal impeller (2) and the inner hole radius R of the centrifugal impeller (2) 1h and the sealing radius R of the annular boss (6) on the back of the centrifugal impeller (2) m Calculate the sealing radius R of the annular boss (6) on the back of the centrifugal impeller (2) m and the inner diameter R of the centrifugal impeller (2) 1h Axial force F3 within the range; By adjusting the sealing radius R of the annular boss (6) on the back of the centrifugal impeller (2) m , change the axial force F2 and the axial force F3 so that (F0+F1)-(F2+F3)≥1kN, and then solve the sealing radius R of the annular boss (6) on the back of the centrifugal impeller (2) m The minimum value of .

6. The method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor according to claim 5, characterized in that: The calculation formula of axial force F0 is:

7. The method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor according to claim 6, characterized in that: The calculation formula of the axial force F1 is:

8. The method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor according to claim 7, characterized in that: The calculation formula of axial force F2 is:

9. The method for calculating the size of an impeller for improving the axial force of a CO2 centrifugal compressor according to claim 8, characterized in that: The calculation formula of axial force F3 is:

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