JPH06272698A - Axial gap control method for centrifugal compressor - Google Patents

Abstract

(57) [Abstract] [Purpose] Completely shut off the leak gas from the high-pressure compressor impeller to the atmosphere to the movable part of the casing shroud to improve the compressor performance and reliability. Especially. In a centrifugal compressor in which a rotary shaft 2 supporting a compressor impeller 1 is supported by a radial bearing 3 and a thrust bearing 4, the end face of the compressor impeller 1 facing the end face of the compressor impeller 1 caused by thermal deformation of the rotary shaft 2 is opposed. The change in the axial gap between the casing 5 and the casing 5 attached thereto is detected from the relationship between the output of the displacement sensor 10 installed on the rear surface of the compressor impeller 1 and the initial gap, and this detection signal is stored inside the casing 5. Output to the attached electromagnet 6, and the ring-shaped shroud 7 is driven by the attraction force with the magnet 8 installed so as to face the electromagnet 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial clearance control method for a centrifugal compressor suitable for controlling the clearance of a centrifugal compressor used in an air separation device or the like.

[0002]

2. Description of the Related Art As a conventional technique for controlling a clearance between an end face of an impeller and a shroud provided on a casing, Japanese Patent Publication Shohei 2
No. 19319 gazette, the portion of the compressor casing that surrounds the impeller facing the impeller blade tip is a movable casing that is driven by gear drive, and is divided into equal parts in the circumferential direction, and each is adjusted by an adjusting operation device. Some are mobile and can always maintain high-efficiency operation.

[0003]

DISCLOSURE OF THE INVENTION In a centrifugal compressor,
The reason for optimizing the clearance between the impeller and the casing shroud is to reduce the leakage loss and the friction loss of the fluid to improve the impeller efficiency. If too much, the effect of fluid friction loss becomes stronger. On the other hand, the reason why it is difficult to maintain and improve the optimum clearance is not only the processing accuracy of the shroud surface of the casing part and the end surface of the impeller and the combined accuracy of both, but also deformation due to shaft resonance occurring during rotation or temperature change during driving operation. This is due to the thermal deformation of the member that corresponds to the above.However, regarding the shaft resonance that occurs during rotation of the former, at the present time especially by establishing the technology of bearing support and operating at a rotation speed that avoids shaft resonance, It doesn't matter. For this reason, in the above-mentioned conventional technique, the latter is considered in consideration of the thermal deformation so that the device can maintain an optimum gap.

However, in the above-mentioned prior art, since the drive mechanism section of the movable casing extends from the atmospheric pressure section to the high-pressure compressor impeller section, and a plurality of similar drive mechanism sections exist in the circumferential direction, leak gas is prevented. Sealing technology for shutting off is required. Further, in order to maintain the gap between the impeller and the casing shroud at an optimum position at all times, it is important to improve the response and controllability of the controller. Since it is necessary to control a plurality of movable casings at the same time, there is a problem that responsiveness and controllability may be hindered and an expensive control device may be provided.

An object of the present invention is to completely shut off a leak gas from a high-pressure compressor impeller to an atmospheric portion with respect to a movable part of a casing shroud, thereby improving compressor performance and reliability. Especially. Another object is to minimize the detector, improve the responsiveness and controllability of the controller, and reduce the cost.

[0006]

The object is to centrifugally compress a rotary shaft supporting an impeller for a compressor by an oil or gas bearing or a magnetic bearing composed of an electromagnet and a displacement sensor for detecting the rotary shaft. In the machine, the change in the axial clearance between the end surface of the compressor impeller and the casing part that is provided to face the end surface of the compressor impeller caused by the thermal deformation of the rotary shaft is changed by one or more installed on the rear surface of the compressor impeller. Detected from the relationship between the displacement sensor output and the initial back clearance, the detection signal is output to one or more electromagnets attached inside the casing, and the ring-shaped shroud is attracted by a magnet installed so as to face the electromagnets. Is achieved by driving.

In the turbine / compressor in which the expansion turbine impeller is attached to one side of the rotary shaft, the same clearance control as described above is performed for the expansion turbine impeller. As the cooling gas for the shroud driving electromagnet, the process gas that has been boosted by the compressor and then cooled by the cooler or the gas in the auxiliary tank whose temperature can be adjusted is used.

As a driving means for the shroud, a ring-shaped rigid body and a ring-shaped shroud having bellow rings mounted on the inner and outer circumferences thereof are attached to a casing portion facing the end surface of the compressor impeller, while corresponding to a detection signal. A part of the process gas is controlled by a supply valve and a leak valve, and introduced into the casing and the cavity formed of the bellow ring and the ring-shaped rigid body.

[0009]

The centrifugal compressor supports axial movement by means of thrust bearings and circumferential movement by means of radial bearings. Therefore, the axial clearance between the end surface of the compressor impeller set in the initial stage and the casing portion provided to face the end surface is kept constant. If the operation is continued under such a condition, for example, heat generation due to wind loss of the thrust portion in the bearing portion or heat generation of the electromagnet portion when using the magnetic bearing occurs, while a high temperature turbine or a low temperature turbine is connected. Thermal stress is generated in the rotating shaft supporting the impeller in the ambient temperature environment of the compressor of the type, and the rotating shaft is thermally deformed. Therefore, the initial clearance maintained at the optimum position changes due to the thermal deformation of the rotating shaft, and in particular, when thermal expansion occurs, the impeller end surface and the casing part come into contact with each other, causing damage to the impeller end surface. Becomes Therefore, the contraction change of the axial gap between the casing part attached to face the end face of the compressor impeller caused by the thermal expansion of the rotary shaft is output by the displacement sensor installed on the rear face of the compressor impeller. And the initial back clearance,
This detection signal is converted into a voltage and then applied to an electromagnet attached inside the casing. As a result, the ring-shaped shroud is lifted by the thermal expansion of the rotating shaft due to the suction force of the magnet installed on the surface installed so as to face the electromagnet, and the compressor shaft is lifted, maintaining the optimum axial clearance. To be done. Further, at this time, the electromagnet transmits the force to the magnet without making contact inside the casing, so that the gas flowing in the compressor is transferred to a predetermined flow path without leaking to the outside. Further, since the change in the axial clearance due to the thermal deformation of the rotating shaft is sensed only on the back surface of the compressor impeller, the response and controllability are excellent, and the control can be performed by an inexpensive control device.

Turbines used in air separation devices, etc.
In the case of a compressor, the same axial clearance control is performed for the expansion turbine impeller facing the compressor impeller via the rotary shaft.

According to a fourth aspect of the present invention, the heat generated in the electromagnet portion is generated by the process gas flowing through the existing gas line, whereby unnecessary equipment is not required and the life of the electromagnet is improved. It has the effect of maintaining reliability. At the same time, there is an effect that it can be used as a cooling source for suppressing thermal deformation generated in the casing.

[0012] Claim 5 can be used as an alternative to Claim 4, and is also effective as a backup when the process gas line of Claim 4 is stopped.

According to a sixth aspect of the present invention, which has the same effect as that of the second aspect, the action is as follows: the ring-shaped rigid body and the inner and outer circumferences of the ring-shaped rigid body in the casing portion facing the end surface of the compressor impeller. A ring-shaped shroud with a bellows ring is attached to the upper part of the process gas, and a part of the process gas corresponding to the detection signal is controlled by a supply valve and an exhaust valve to form a casing part, the bellows ring and a ring-shaped rigid body. The optimum axial clearance is maintained by introducing it into the cavity.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a compressor impeller having a plurality of blades on a disk, 2 denotes a rotary shaft for supporting and rotating the compressor impeller 1,
3 is a radial bearing that supports the displacement of the rotary shaft 2 in the circumferential direction, 4
Is a thrust bearing that supports axial displacement at a thrust portion attached to the rotary shaft 2, 5 is a casing that surrounds the compressor impeller 1, and 6 is a compressor impeller 1 in the casing 5. The electromagnets 7 are installed so as to face each other in the axial direction, 7 is a ring-shaped shroud that faces the electromagnet 6 and the compressor impeller 1, and 8 is a position that faces the electromagnet 6 of the shroud 7. A magnet attached to the magnet 6 and having an attraction relationship with the electromagnetic 6 stone, and 9 a casing 5 and a shroud 7 at the lower end of the electromagnet 6.
A connecting rod for connecting the above and preventing circumferential driving, 10 is a displacement sensor for measuring the amount of displacement of the back face of the compressor impeller 1, 11 is a power supply for applying a predetermined voltage to the electromagnet 6, Reference numeral 12 converts the displacement amount when comparing the output of the displacement sensor 10 with the initial clearance amount on the rear surface of the impeller when the clearance between the end of the compressor impeller 1 and the shroud 7 is optimized,
It is a controller for an electromagnet which is an input of the power supply 11.

Next, the operation of this embodiment will be described. The low-pressure gas flowing in from the impeller inlet portion (left side in the drawing) of the compressor impeller 1 is decelerated by flowing in the impeller, and the decelerated component recovers in pressure and becomes high-pressure gas from the outer peripheral end of the impeller. Is discharged. Since the rotary shaft 2 is supported by the radial bearing 3 and the thrust bearing 4, the rotary shaft 2 can be stably rotated while keeping the gap between the shroud 7 and the end face of the compressor impeller 1 at an optimum gap. When the operation is continued under such a condition, heat is generated in the bearing part due to windage loss of the thrust part or heat is generated by the electromagnet when the magnetic bearing is used, while the end part facing the compressor is generated. For example, in an ambient temperature environment of a type in which a high temperature turbine is connected, thermal stress is generated in the rotary shaft 2 supporting the compressor impeller 1, and the rotary shaft 2 thermally expands in the axial direction. The thermally expanded rotary shaft 2 is supported by the thrust bearing 4, so that the compressor impeller 1 moves in a certain axial direction (on the left side in the figure) to widen the gap on the rear face of the impeller, and the shroud 7
And the gap between the end surface of the impeller 1 for compressor and the end surface of the compressor impeller tries to narrow. At this time, in the electromagnet controller 12, the initial clearance amount on the rear surface of the impeller and the clearance on the rear surface of the impeller detected by the displacement sensor 10 when the clearance between the end of the compressor impeller 1 and the shroud 7 is optimized. The amount of spread is compared, the amount of change is obtained, and converted into an electrical signal. By applying a power supply voltage corresponding to the electric signal to the electromagnet 6, an attractive force acts on the magnet 8 facing the electromagnet 6, and the shroud 7 is supported by the connecting rod 9 in the circumferential direction. Move to the side. Therefore, even if thermal expansion occurs, the gap between the end of the compressor impeller 1 and the shroud 7 is kept at an optimum gap.

According to this embodiment, the efficiency of the rotary shaft can be improved during operation by preventing the impeller efficiency from deteriorating due to thermal deformation of the rotary shaft during operation and change of the clearance. Also,
At this time, since the electromagnet transmits the force to the magnet without contacting inside the casing, the gas flowing in the compressor is transferred to a predetermined flow path without leaking to the outside, improving the compressor performance and reliability. There is also an effect to do. Furthermore, since the change in the axial clearance due to the thermal deformation of the rotating shaft is sensed only on the back surface of the compressor impeller, it is possible to perform control with an inexpensive control device having excellent responsiveness and controllability. In the present embodiment, the one in which the electromagnet attracts has been described, but it is also possible to control the repulsion to reduce the axial gap, and it is also easy to simultaneously perform the attraction and the repulsion.

FIG. 2 shows a turbine compressor according to another embodiment of the present invention. Reference numeral 13 denotes an expansion turbine impeller facing the compressor impeller 1 and connected to the rotary shaft 2. The description of other symbols is the same as that of FIG.
This figure shows, for example, a turbine used in an air separation device.
This is intended for a compressor, and the expansion turbine impeller 13 is also subjected to the same axial clearance control as in FIG. 1. The effect is also the same as in FIG. 1, but in this embodiment, the turbine efficiency is also improved. Has the effect of

FIG. 3 shows a peripheral view of a compressor impeller according to another embodiment of the present invention. 14 is a main line for transferring the process gas exhausted from the compressor outlet to the next equipment, 15 is a cooler for cooling the high temperature gas in the main line 14, and 16 is a part of the cooling process gas flowing through the main line 14. Casing 5
An air supply line for supplying to the electromagnet 6 therein, a reference numeral 17 for adjusting the flow rate of the process gas flowing into the air supply line 16, and a reference numeral 18 for a process gas return line for recovering the calorific value of the electromagnet 6. In the present embodiment, under the same operation as in FIG. 1, the heat generated in the electromagnet 6 is generated by the process gas flowing through the existing gas line, so that unnecessary equipment is not required and the life of the electromagnet 6 is improved. It has the effect of maintaining reliability. At the same time, there is an effect that it can be used as a cooling source for suppressing thermal deformation generated in the casing.

FIG. 4 shows a peripheral view of a compressor impeller according to still another embodiment of the present invention. 19 is an electromagnet 6 in the casing 5.
It is an auxiliary tank with a temperature control for cooling.
While this embodiment is used as an alternative to the embodiment of FIG. 3, it is installed in parallel with the line of FIG. 3 and is also effective as a backup when the main line 14 of the process gas of FIG. 3 is stopped.

FIG. 5 shows a peripheral view of a compressor impeller according to another embodiment of the present invention. Reference numeral 20 is a ring-shaped bellows having a ring-shaped rigid body and a bellows ring attached on its inner and outer circumferences in a casing portion facing the end face of the compressor impeller 1, and 21 is a cavity formed by the casing portion and the bellows ring and the ring-shaped rigid body. An electronic pressure gauge for constantly monitoring the pressure of a section, 22 is a bellows controller that outputs a control signal in consideration of the situation of the electronic pressure gauge 21, and 23 is a control signal of the bellows controller 22. A supply valve for replenishing the generated gas pressure to the casing portion and the hollow portion formed by the bellow ring and the ring-shaped rigid body from a part of the process gas, and 24 is a gas pressure corresponding to a control signal of the bellow controller 22. Is an exhaust valve for discharging gas from the cavity. The operation and effect of this embodiment are basically the same as those of the embodiment of FIG. 1, but there is an effect that the axial clearance can be controlled with a simpler structure by changing the pressure of the cavity.

FIG. 6 shows a peripheral view of a compressor impeller according to another embodiment of the present invention. Reference numeral 25 is an exhaust line for exhausting the gas in the hollow portion composed of the casing portion and the bellow ring and the ring-shaped rigid body to the outside. While this embodiment is used as an alternative to the embodiment of FIG. 5, it is also effective as a backup when it is installed in parallel with the line of FIG. 5 and the process gas line of FIG. 5 stops.

[0022]

According to the present invention, the gap between the end of the impeller for the compressor and the shroud exists at the optimum position even when the rotary shaft is thermally deformed due to the heat generation of the bearing and the operating environment. Therefore, it is possible to prevent the efficiency of the impeller from lowering and maintain high efficiency during operation. In addition, the structure that completely shuts off the leak gas from the high pressure compressor impeller part to the atmospheric part with respect to the movable part of the casing shroud allows the gas flowing in the compressor to flow through the specified part without leaking to the outside. There is also an effect that it is transferred to the route and reliability is improved. Furthermore, since the change in the axial clearance due to the thermal deformation of the rotating shaft is sensed only on the back surface of the compressor impeller, it is possible to perform control with an inexpensive control device having excellent responsiveness and controllability.

Further, since heat generated in the electromagnet is generated by the process gas flowing through the existing gas line, unnecessary facilities are not required, the life of the electromagnet is improved, and reliability is maintained. At the same time, there is an effect that it can be used as a cooling source for suppressing thermal deformation generated in the casing. Further, it is effective as a backup when the process gas line is stopped.

[Brief description of drawings]

FIG. 1 is a cross-sectional view around a compressor impeller showing an embodiment of the present invention.

FIG. 2 is a sectional view of a turbine compressor according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view around a compressor impeller according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view around a compressor impeller according to still another embodiment of the present invention.

FIG. 5 is a cross-sectional view around a compressor impeller according to another embodiment of the present invention.

FIG. 6 is a cross-sectional view around a compressor impeller according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Impeller for compressor, 2 ... Rotating shaft, 3 ... Radial bearing, 4
... thrust bearing, 5 ... casing, 6 ... electromagnet, 7 ... ring-shaped shroud, 8 ... magnet, 9 ... connecting rod, 10 ... displacement sensor, 11 ... power supply, 12 ... electromagnet controller, 13 ...
Expansion turbine impeller, 14 ... Main line, 15 ... Cooler,
16 ... Air supply line, 17 ... Regulator valve, 18 ... Return line, 19 ... Auxiliary tank, 20 ... Ring-shaped bellows, 21 ...
Electronic pressure gauge, 22 ... Bellows controller, 23 ... Supply valve, 24 ... Exhaust valve, 25 ... Exhaust line.

Claims (7)

[Claims] 1. A centrifugal compressor in which a rotary shaft supporting a compressor impeller is supported by an oil or gas bearing or a magnetic bearing composed of an electromagnet and a displacement sensor for detecting the rotary shaft. At least one or more displacement sensor outputs installed on the rear surface of the compressor impeller and the initial rear surface are used to detect changes in the axial clearance between the casing portion attached to face the end surface of the compressor impeller caused by the deformation. The ring-shaped shroud, which is a part of the casing attached to face the end face of the compressor impeller, is driven by detecting from the relationship of the gap and outputting this detection signal to the drive source that is not communicating with the inside of the compressor. A method for controlling the axial clearance of a centrifugal compressor characterized by: 2. The method for controlling the axial clearance of a centrifugal compressor according to claim 1, wherein the detection signal is output to at least one electromagnet provided inside the casing, and the magnet is installed so as to face the electromagnet. An axial clearance control method for a centrifugal compressor, characterized in that the ring-shaped shroud is driven by a suction force (or a repulsive force) with. 3. An axial clearance control method for a turbine / compressor according to the axial clearance control method for a centrifugal compressor of claim 1, wherein clearance control is performed for the rotary shaft expansion turbine impeller. 4. The axial clearance control method for a centrifugal compressor according to claim 1, wherein a part of the process gas cooled by a cooler after being pressurized by the compressor is introduced as a cooling gas for said shroud driving electromagnet. A method for controlling the axial clearance of a centrifugal compressor, which is characterized in that 5. The method for controlling the axial clearance of a centrifugal compressor according to claim 4, wherein the gas in the auxiliary tank whose temperature is adjustable is introduced as the cooling gas for the electromagnet for driving the shroud. Axial clearance control method. 6. The method for controlling the axial clearance of a centrifugal compressor according to claim 1, wherein a ring-shaped rigid body and a bellows ring are formed on the inner and outer circumferences of the ring-shaped rigid body in the casing portion facing the end surface of the compressor impeller. While the attached ring-shaped shroud is attached, a part of the process gas corresponding to the detection signal is controlled by a supply valve and an exhaust valve, and is introduced into a cavity portion composed of a casing portion, the bellow ring and a ring-shaped rigid body. An axial clearance control method for a centrifugal compressor, which is characterized in that 7. The axial clearance control method for a centrifugal compressor according to claim 6, wherein gas in an auxiliary tank whose temperature is adjustable is introduced into the cavity. .