Centrifugal compressor and control method thereof

Abstract

The invention discloses a centrifugal compressor and a control method, and relates to the technical field of compressors. A first cavity is formed by the front face of the impeller and an inlet of the volute, a second cavity is formed by the back face of the impeller and the inner wall of the volute, and a third cavity is formed by the circumferential face of the impeller and an outlet of the volute; an adjusting channel with adjustable flux is arranged between the first chamber and the third chamber in a conducting manner; according to the centrifugal compressor and the control method, the adjusting channel communicated with the low-pressure cavity of the inlet of the compressor and the high-pressure cavity of the outlet of the compressor is arranged, the pressure difference of the two sides of the impeller is rapidly adjusted by controlling the flux of the adjusting channel, and then the axial force balance of the impeller rotating shaft is achieved under the dynamic load.

Description

Technical Field

[0001] The present invention relates to the field of compressor technology, and more specifically, to a centrifugal compressor. In addition, the present invention also relates to a control method applied to the centrifugal compressor. Background Art

[0002] When a centrifugal compressor is working, the medium in the chambers on both sides of its impeller is unevenly distributed, causing axial force on the impeller's rotating shaft. The size and direction of the axial force are related to the pressure difference between the chambers on both sides, the impeller diameter, etc. As the impeller speed increases, the pressure difference between the chambers on both sides of the impeller further increases, and the rotating shaft is subjected to greater force, which may seriously cause axial displacement of the rotor, cause bearing strain, friction and collision of moving and static parts, or overload damage to the auxiliary bearing. In particular, the increase in pressure difference when running at full load will increase the risk of equipment damage.

[0003] In the prior art, a mechanical balancing disk is provided in a centrifugal compressor to balance the axial force of the rotating shaft. However, the balancing method in the prior art is only applicable to the axial force adjustment under a fixed load state. When the load at the inlet or outlet of the centrifugal pump fluctuates, the adjustment effect is not sufficient to completely eliminate the axial force generated by the rotation of the impeller, and there is still a risk of axial displacement of the rotor or overload damage to the auxiliary bearing.

[0004] In summary, how to solve the axial force balance of a centrifugal compressor under dynamic load is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a centrifugal compressor, which is provided with an adjustment channel connecting the low-pressure chamber at the compressor inlet and the high-pressure chamber at the outlet. By controlling the flux of the adjustment channel, the pressure difference on both sides of the impeller is quickly adjusted, thereby achieving axial force balance of the impeller shaft under dynamic load.

[0006] Another object of the present invention is to provide a control method applied to the above-mentioned centrifugal compressor to obtain the pressure difference on both sides of the impeller and control the flux of the regulating channel between the low-pressure chamber of the compressor and the high-pressure chamber of the outlet, so as to quickly achieve the pressure balance of the cavities on both sides of the impeller, and then achieve the balance of the axial force of the impeller shaft under dynamic load.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A centrifugal compressor comprising:

[0009] volute;

[0010] An impeller, wherein the front surface of the impeller and the inlet of the volute form a first chamber, the back surface of the impeller and the inner wall of the volute form a second chamber, and the peripheral surface of the impeller and the outlet of the volute form a third chamber;

[0011] Wherein, a flux-adjustable regulating channel is provided between the first chamber and the third chamber.

[0012] Preferably, a first pressure sensor is provided in the first chamber for monitoring the pressure in the first chamber.

[0013] Preferably, a second pressure sensor is provided in the second chamber for monitoring the pressure in the second chamber.

[0014] Preferably, an electric regulating valve is provided in the regulating channel or at the position where it communicates with the third chamber.

[0015] Preferably, auxiliary blades are provided on the back side of the impeller for forming low pressure in the second chamber.

[0016] Preferably, the auxiliary blades are centrifugal blades and are arranged in an annular array on the back of the impeller.

[0017] A control method, applied to any one of the centrifugal compressors described above, comprising:

[0018] Continuously obtaining a pressure difference ΔP between the pressure P1 of the first chamber and the pressure P2 of the second chamber, ΔP=P1-P2;

[0019] Determine whether △P is less than the minimum value of the preset value interval;

[0020] If yes, the flux of the regulating channel is controlled to increase until ΔP is not less than the minimum value of the preset value interval;

[0021] If not, determine whether ΔP is greater than the maximum value of the preset value interval;

[0022] If yes, the flux of the regulating channel is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval;

[0023] If not, the current flux of the regulation channel is maintained.

[0024] Preferably, the back of the impeller is provided with auxiliary blades;

[0025] If yes, then controlling the flux of the regulating channel to increase until ΔP is not less than the minimum value of the preset value interval, further comprising:

[0026] The speed of the impeller is controlled to increase.

[0027] Preferably, the back of the impeller is provided with auxiliary blades;

[0028] If yes, the flux of the regulating channel is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval, further comprising:

[0029] The rotation speed of the impeller is controlled to decrease.

[0030] Preferably, the back of the impeller is provided with auxiliary blades;

[0031] If yes, the flux of the regulating channel is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval, and replaced by:

[0032] If yes, the impeller is controlled to reduce its rotation speed until ΔP is no greater than the maximum value of the preset value interval.

[0033] The centrifugal compressor provided by the present invention has at least the following beneficial effects compared with the prior art:

[0034] When the impeller rotates at high speed, a low-pressure chamber is formed at the first chamber and the second chamber on both sides of the impeller, and a high-pressure chamber is formed at the third chamber at the volute outlet. When the pressure in the first chamber and the second chamber is unbalanced, the impeller will be pushed to move toward the side with low pressure, that is, the impeller shaft generates an axial force in the corresponding direction. At this time, an adjustment channel is set between the first chamber and the third chamber on the front side of the impeller, and the flux of the adjustment channel is regulated, so that the high-pressure medium in the third chamber can quickly enter or quickly stop entering the first chamber, and then the pressure of the first chamber can be quickly regulated to eliminate the pressure difference between the first chamber and the second chamber, so as to meet the balanced adjustment of the axial force under dynamic load. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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 use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0036] Figure 1 This is a schematic structural diagram of a specific centrifugal compressor provided by the present invention;

[0037] Figure 2 A cross-sectional view of a centrifugal compressor provided by the present invention;

[0038] Figure 3 This is a schematic structural diagram of the back side of the specific impeller provided by the present invention;

[0039] Figure 4 This is a flow chart of the specific control method provided by the present invention.

[0040] In the picture:

[0041] 1. Volute; 2. Impeller; 21. Auxiliary blades; 3. Adjustment channel; 31. Adjustment valve; 4. First chamber; 5. Second chamber; 6. Third chamber. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] The core of the present invention is to provide a centrifugal compressor, which is equipped with an adjustment channel connecting the low-pressure chamber at the compressor inlet and the high-pressure chamber at the outlet. By controlling the flux of the adjustment channel, the pressure difference on both sides of the impeller is quickly adjusted, thereby achieving axial force balance of the impeller shaft under dynamic load.

[0044] Another core of the present invention is to provide a control method including the above-mentioned centrifugal compressor, obtain the pressure difference on both sides of the impeller, and control the flux of the regulating channel between the low-pressure chamber of the compressor and the high-pressure chamber of the outlet, so as to quickly achieve the pressure balance of the cavities on both sides of the impeller, and then achieve the balance of the axial force of the impeller shaft under dynamic load.

[0045] Please refer to Figure 1 and Figure 2 , a centrifugal compressor comprising:

[0046] volute 1;

[0047] The impeller 2 has a front surface and an inlet of the volute 1 forming a first chamber 4, a back surface and an inner wall of the volute 1 forming a second chamber 5, and a peripheral surface of the impeller 2 and an outlet of the volute 1 forming a third chamber 6.

[0048] A flux-adjustable regulating channel 3 is provided between the first chamber 4 and the third chamber 6 .

[0049] like Figure 2As shown, a first chamber 4 and a second chamber 5 are formed on both sides of the impeller 2 respectively. The first chamber 4 is close to the inlet of the volute 1, and a third chamber 6 is formed at the circumferential surface of the impeller 2 and the outlet of the volute 1. Due to the structural limitations of the impeller 2, the third chamber 6 simultaneously connects the first chamber 4 and the second chamber 5. When the impeller 2 rotates at high speed, the first chamber 4 and the second chamber 5 both form low-pressure chambers, while the third chamber 6 forms a high-pressure chamber. The pressures of the first chamber 4 and the third chamber 6 fluctuate under the influence of dynamic loads. When the pressures of the first chamber 4 and the second chamber 5 are unbalanced, a force that drives the axial movement of the impeller 2 is generated, that is, the axial force of the rotating shaft of the impeller 2 is unbalanced.

[0050] At this time, by providing an adjustment channel 3 between the first chamber 4 and the third chamber 6, the high-pressure medium in the third chamber 6 can enter the first chamber 4 through the adjustment channel 3, thereby changing the pressure of the first chamber 4 to eliminate the pressure difference between the first chamber 4 and the second chamber 5, that is, to eliminate the axial force of the rotating shaft of the impeller 2;

[0051] Moreover, the flux of the regulating channel 3 is adjustable, that is, by changing the flux of the regulating channel 3, the pressure of the first chamber 4 can be accurately adjusted, that is, the axial force of the rotating shaft of the impeller 2 under dynamic load can be adjusted;

[0052] At the same time, since the third chamber 6 is a high-pressure chamber and the first chamber 4 is a low-pressure chamber, that is, the pressure of the third chamber 6 is much greater than that of the first chamber 4, the high-pressure medium in the third chamber 6 can quickly pass through the adjustment channel 3, so that the pressure of the first chamber 4 can be quickly adjusted, that is, the axial force adjustment of the rotating shaft of the impeller 2 under high-frequency dynamic load conditions is met.

[0053] For example, when the pressure in the first chamber 4 is lower than that in the second chamber 5, the flux of the regulating channel 3 is increased, so that the high-pressure medium in the third chamber 6 can be quickly introduced into the first chamber 4, thereby increasing the pressure in the first chamber 4 and eliminating the pressure difference between the first chamber 4 and the second chamber 5, thereby achieving a balance in the axial force of the impeller 2.

[0054] When the pressure in the first chamber 4 is greater than that in the second chamber 5, the flux of the regulating channel 3 is reduced, or the regulating channel 3 is directly cut off to reduce the flow of the high-pressure medium in the third chamber 6 to the first chamber 4, so that the pressure in the first chamber 4 can be quickly reduced, eliminating the pressure difference with the second chamber 5, so as to achieve the balance of the axial force of the rotating shaft of the impeller 2.

[0055] In some embodiments, a first pressure sensor is provided in the first chamber 4 for monitoring the pressure in the first chamber 4 .

[0056] A first pressure sensor is set in the first chamber 4, such as a first pressure sensor is set at the diffuser at the inlet of the volute 1, to obtain the pressure in the first chamber 4 in real time, which is then used to accurately feedback the impact of the flux regulation of the regulation channel 3 on the pressure of the first chamber 4.

[0057] In some embodiments, a second pressure sensor is provided in the second chamber 5 for monitoring the pressure in the second chamber 5 .

[0058] A second pressure sensor is provided in the second chamber 5 to obtain the pressure of the second chamber 5 in real time, and then compare it with the pressure of the first chamber 4 to accurately obtain the pressure difference between the first chamber 4 and the second chamber 5, so as to provide the regulating channel 3 with accurate flux regulation.

[0059] In some embodiments, an electric regulating valve 31 is provided at the regulating channel 3 or the position where the regulating channel 3 communicates with the third chamber 6 .

[0060] like Figure 1 and Figure 2 As shown, an external or internal pipeline is used as a channel to connect the first chamber 4 and the third chamber 6, and an electric regulating valve 31 is integrated in the pipeline. By detecting the pressure difference between the first chamber 4 and the second chamber 5, the flux of the electric regulating valve 31 is regulated, that is, the flux of the regulating channel 3 is changed, and then the pressure of the first chamber 4 is adjusted to eliminate the pressure difference between the first chamber 4 and the second chamber 5, and then eliminate the axial force of the rotating shaft of the impeller 2.

[0061] In some embodiments, the electric regulating valve 31 is set at the communication position between the regulating channel 3 and the third chamber 6. When the flux of the electric regulating valve 31 is small or closed, it can effectively avoid high pressure in the pipeline, thereby reducing the risk of pipeline rupture.

[0062] In some embodiments, auxiliary blades 21 are provided on the back side of the impeller 2 for forming a low pressure in the second chamber 5 .

[0063] like Figure 2 and Figure 3 As shown, auxiliary blades 21 are synchronously provided on the back of the impeller 2. When the impeller 2 rotates at high speed, the auxiliary blades 21 can drive the medium in the second chamber 5 to perform centrifugal motion, and then enter the third chamber 6, so that the second chamber 5 presents a negative pressure close to that of the first chamber 4, which helps to improve the pressure balance on both sides of the impeller 2. At the same time, since the second chamber 5 is at a negative pressure, the leakage of the medium at the junction of the rotating shaft and the volute 1 is reduced.

[0064] In some embodiments, the auxiliary blades 21 are centrifugal blades and are arranged in an annular array on the back of the impeller 2 .

[0065] like Figure 3As shown, the auxiliary blades 21 are centrifugal blades. When the impeller 2 rotates, the auxiliary blades 21 act to form a negative pressure in the second chamber 5. The faster the impeller 2 rotates, the smaller the pressure in the second chamber 5. By reducing the speed of the impeller 2, the pressure in the second chamber 5 rises. Then, by adjusting the speed of the impeller 2, the pressure in the second chamber 5 can be changed to balance the pressures in the first chamber 4 and the second chamber 5, which helps to quickly achieve axial force balance of the rotating shaft.

[0066] In addition to the centrifugal compressors disclosed in the above embodiments, the present invention further provides a control method for a centrifugal compressor applied to any of the above embodiments, comprising:

[0067] Continuously obtain the pressure difference ΔP between the pressure P1 of the first chamber 4 and the pressure P2 of the second chamber 5, ΔP=P1-P2;

[0068] Determine whether △P is less than the minimum value of the preset value interval;

[0069] If yes, the flux of control channel 3 is increased until ΔP is not less than the minimum value of the preset value interval;

[0070] If not, determine whether ΔP is greater than the maximum value of the preset value interval;

[0071] If yes, the flux of the control regulating channel 3 is reduced until ΔP is no greater than the maximum value of the preset value interval;

[0072] If not, keep regulating the current flux of channel 3.

[0073] like Figure 4 As shown, during the operation of the centrifugal compressor, the pressures P1 and P2 in the first chamber 4 and the second chamber 5 are continuously obtained, the pressure difference △P between the two is obtained by calculation, and the pressure difference △P is compared with the preset value range. When △P is within the preset value range, the pressure difference △P on both sides of the surface impeller 2 is within a reasonable range, that is, the pressures in the first chamber 4 and the second chamber 5 are balanced, or the axial force is insufficient to cause axial displacement of the rotor and overload damage to the auxiliary bearing; when the pressure difference △P exceeds the preset value range, the flux of the regulating channel 3 is adjusted to control the amount of high-pressure medium in the third chamber 6 entering the first chamber 4, and then the pressure of the first chamber 4 is adjusted so that the pressure difference △P between it and the second chamber 5 returns to the preset value range.

[0074] Using a preset value interval as a comparison standard instead of a fixed preset value can reduce the frequency of adjustment of the adjustment channel 3, avoid frequent pressure fluctuations in the first chamber 4 caused by frequent activation of the adjustment mechanism, and ensure the smooth operation of the centrifugal compressor.

[0075] In some embodiments, the back of the impeller 2 is provided with auxiliary blades 21;

[0076] In the above embodiment, if the answer is yes, the step of controlling the flux of the regulating channel 3 to increase until ΔP is not less than the minimum value of the preset value interval further includes the following steps:

[0077] The speed of the impeller 2 is controlled to increase.

[0078] It should be noted that when the flux of the regulating channel 3 increases, the amount of high-pressure medium in the third chamber 6 entering the first chamber 4 increases, and the pressure difference between the first chamber 4 and the third chamber 6 decreases, which affects the working efficiency of the centrifugal compressor. Therefore, by arranging auxiliary blades 21 on the back of the impeller 2, by adjusting the speed of the impeller 2, the pressure of the second chamber 5 is adjusted, and the flux adjustment of the regulating channel 3 is coordinated, the pressure difference △P between the first chamber 4 and the second chamber 5 is quickly reduced, and the impact on the pressure difference between the first chamber 4 and the third chamber 6 is reduced, that is, the impact on the working efficiency of the centrifugal compressor is reduced.

[0079] In some embodiments, the back of the impeller 2 is provided with auxiliary blades 21;

[0080] In the above embodiment, if the answer is yes, the step of controlling the flux of the regulating channel 3 to decrease until ΔP is no greater than the maximum value of the preset value interval further includes the following steps:

[0081] The rotation speed of the impeller 2 is controlled to decrease.

[0082] When the flux of the regulating channel 3 decreases, the pressure of the first chamber 4 can be reduced accordingly. When the pressure of the second chamber 5 is still lower than that of the first chamber 4, or by reducing the flux of the regulating channel 3 and the pressure drop rate of the first chamber 4 is slow, the pressure of the second chamber 5 can be increased to reduce the pressure difference △P between the first chamber 4 and the second chamber 5. That is, by reducing the rotation speed of the impeller 2, the influence of the auxiliary blades 21 on the pressure of the second chamber 5 is reduced to increase the pressure of the second chamber 5, thereby quickly achieving pressure balance on both sides of the impeller 2 and achieving axial force balance of the rotating shaft of the impeller 2.

[0083] In some embodiments, the back of the impeller 2 is provided with auxiliary blades 21;

[0084] In the above embodiment, the step of: if yes, controlling the flux of the regulating channel 3 to decrease until ΔP is no greater than the maximum value of the preset value interval can be replaced by:

[0085] If yes, the speed of the impeller 2 is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval.

[0086] In actual use, there is a problem that even if the adjustment channel 3 is completely cut off, the pressure difference △P between the first chamber 4 and the second chamber 5 is still greater than the maximum value of the preset value range. At this time, the pressure in the second chamber 5 can only be increased by reducing the speed of the impeller 2, so that the pressure difference △P between the first chamber 4 and the second chamber 5 returns to the preset value range, that is, the axial force balance of the rotating shaft of the impeller 2 is achieved.

[0087] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0088] The centrifugal compressor and control method provided by the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A centrifugal compressor, characterized in that: include: volute (1); An impeller (2), wherein the front surface of the impeller (2) and the inlet of the volute (1) form a first chamber (4), the back surface of the impeller (2) and the inner wall of the volute (1) form a second chamber (5), and the peripheral surface of the impeller (2) and the outlet of the volute (1) form a third chamber (6); A flux-adjustable regulating channel (3) is provided between the first chamber (4) and the third chamber (6).

2. The centrifugal compressor according to claim 1, wherein A first pressure sensor is provided in the first chamber (4) for monitoring the pressure in the first chamber (4).

3. The centrifugal compressor according to claim 1, wherein: A second pressure sensor is provided in the second chamber (5) for monitoring the pressure in the second chamber (5).

4. The centrifugal compressor according to claim 1, wherein: An electric regulating valve (31) is provided at the regulating channel (3) or at a position where the regulating channel (3) communicates with the third chamber (6).

5. The centrifugal compressor according to any one of claims 1 to 4, characterized in that: Auxiliary blades (21) are provided on the back side of the impeller (2) for forming a low pressure in the second chamber (5).

6. The centrifugal compressor according to claim 5, characterized in that The auxiliary blades (21) are centrifugal blades and are arranged in an annular array on the back of the impeller (2).

7. A control method, characterized in that: The centrifugal compressor according to any one of claims 1 to 6 comprises: Continuously obtaining a pressure difference ΔP between the pressure P1 of the first chamber (4) and the pressure P2 of the second chamber (5), ΔP=P1-P2; Determine whether △P is less than the minimum value of the preset value interval; If yes, the flux of the regulating channel (3) is controlled to increase until ΔP is not less than the minimum value of the preset value interval; If not, determine whether ΔP is greater than the maximum value of the preset value interval; If yes, the flux of the regulating channel (3) is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval; If not, the current flux of the regulating channel (3) is maintained.

8. The control method according to claim 7, characterized in that: Auxiliary blades (21) are provided on the back side of the impeller (2); If yes, the flux of the regulating channel (3) is controlled to increase until ΔP is not less than the minimum value of the preset value interval, and further comprising: Control the rotation speed of the impeller (2) to increase.

9. The control method according to claim 7, characterized in that: Auxiliary blades (21) are provided on the back side of the impeller (2); If yes, the flux of the regulating channel (3) is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval, and further comprising: The rotation speed of the impeller (2) is controlled to decrease.

10. The control method according to claim 7, characterized in that: Auxiliary blades (21) are provided on the back side of the impeller (2); If yes, the flux of the regulating channel (3) is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval, and replaced by: If yes, the rotation speed of the impeller (2) is controlled to decrease until ΔP is no greater than the maximum value of the preset value interval.

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