JPH0861089A - Dynamic pressure gas thrust bearing for turbine compressor - Google Patents

Abstract

PURPOSE: To secure a dynamic pressure gas thrust bearing that is ease of metalworking and excellent in wear and abrasion resistance in expanding an applicable range to a plant by way of improving a load capacity in this dynamic pressure gas thrust bearing capable of promoting the compactification and low-unit cost of a device in addition to cleanliness in environment. CONSTITUTION: In this turbine compressor which has supported a rotator attached with a turbine rotor 8, making high pressure gas into adiabatic expansion, at one and also a compressor rotor 2, making gas into adiabatic compression by dint of power produced by this turbine rotor 8, at the other end with a dynamic gas journal bearing 12 and a dynamic gas thrust bearing 14, a base material of this dynamic gas thrust bearing 14 is made into such material as being ease of machining in particular, and basic form of the bearing is formed into a spiral shape being high in relatively load capacity. In addition, the spiral form tilts a bottom surface of a spiral groove so as to be narrowed in the rotational direction, and a surface of the thrust bearing 14 is subjected to surface reforming and filming by an ion source, thereby improving the extent of wear and abrasion resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic gas thrust bearing for a turbine compressor in which a turbine wheel is attached to one end of a rotor and a compressor wheel is attached to the other end.

[0002]

2. Description of the Related Art As a general prior art for bearings for turbine compressors, for example, Turbomachinery Vol. 21, No. 5, P.
As described in the literature relating to the new technology of turbomachinery for low-temperature equipment in No. 62, an example of using oil bearings for bearings of relatively large air separation devices and gas bearings for bearings of small plants was introduced. ing.

[0003]

The viscosity coefficient of gas is the same as that of oil.
Since the order is 1/1000, the gas bearing has lower load capacity and bearing rigidity than the oil bearing. Therefore, oil bearings are used in large plants that require high load capacity. However, a plant using an oil bearing requires accessory parts such as a refueling device and a pipe connecting the refueling device and the turbine compressor, so that the size of the entire device is inevitably increased.
There is also a problem of environmental degradation due to smoke emission.

On the other hand, a turbine compressor using a gas bearing has a small bearing loss and can effectively use the power on the turbine side for the compressor power, and since there are no accessories such as an oil supply device, it is compact and has a low load capacity. Optimal for plants. However, as described above, since the load capacity and the bearing rigidity are small, the application range is limited to the small size. In addition, there are static pressure type and dynamic pressure type gas bearings.The static pressure type has higher load capacity than the dynamic pressure type, but it is necessary to supply extra gas to the bearing part, which is not economically efficient. There are drawbacks such as the structure of the piping for supplying gas and the supply section becoming complicated. Dynamic gas bearings can compensate for the drawbacks of oil bearings and hydrostatic bearings, but they do not work as bearings because pressure is not generated to support the load unless the bearing surface has a relative speed, and the shaft and bearing are solid when starting and stopping. You will come into contact. Therefore, in order to make a dynamic pressure gas bearing, it is necessary to select a hard material that is not damaged or worn away even if solid contact occurs. On the other hand, in the case of a hard material, it is generally difficult to process, and when performing fine processing such as a complicated groove, the processing cost becomes high.

An object of the present invention is to expand the range of application to a plant by increasing the load capacity of a dynamic pressure gas bearing, which has a clean environment, can make the apparatus compact and reduce the cost.
An object of the present invention is to provide a dynamic pressure gas thrust bearing that is easy to machine and has excellent wear resistance.

[0006]

SUMMARY OF THE INVENTION The above object is to rotate a turbine impeller for adiabatically expanding high-pressure gas at one end and a compressor impeller for adiabatically compressing gas by the power generated by the turbine impeller at the other end. In a turbine compressor in which a body is supported by a dynamic pressure gas journal bearing and a dynamic pressure gas thrust bearing, especially the base material of the dynamic pressure gas thrust bearing is a material that is easy to machine, and the basic shape of the bearing is a spiral with a relatively high load capacity. The shape of the spiral is such that the bottom surface of the spiral groove is inclined or stepped so that it narrows in the direction of rotation, or both, and the thrust bearing surface or the opposing surface or both are surface-modified or film-formed by an ion source. , By improving wear resistance.

[0007]

For example, when the rotary body is used with a vertical shaft with the compressor side facing downward, the shaft and the bearing are in solid contact with each other and are stationary. When gas is supplied to the turbine side in this state, the turbine is driven by the turbine impeller and turbine power, and thrust force acts upward. On the other hand, in the thrust portion, the gas in the bearing chamber is sucked toward the inner peripheral side from the outer peripheral side, the pressure in the spiral groove increases, and the force that pushes down the rotating body works. At this time, since the bottom surface of the spiral groove is inclined so as to narrow in the rotation direction, the load capacity generated by the spiral groove and the wedge-shaped gap existing in the rotation direction increase the bearing load capacity by 20 to 30% compared to the spiral unit. To do. The rotating body involves some solid contact in the initial floating stage, and the thrust force and the bearing load capacity are balanced at a predetermined rotation speed to maintain a predetermined gap. Further, at the time of stop, contrary to the above, the gas supply to the turbine side is stopped, so that the rotation speed is reduced and the thrust force and the bearing load capacity are reduced. For this reason, the shaft and the bearing are stopped with solid contact. However, abrasion or seizure caused by solid contact at the time of starting or stopping can be prevented because the surface of the thrust bearing is surface-modified or film-formed by an ion source to improve abrasion resistance.

As a result, the range of application of the turbine compressor can be expanded by improving the load capacity, and the unnecessary pipe or oil supply device can be eliminated to achieve compactness, cost reduction and cleanliness. In addition, since the base material of the thrust bearing is a material that can be easily processed, this bearing can easily manufacture bearings with complicated shapes. Surface modification or film formation on the thrust bearing surface or counter surface with an ion source Therefore, the bearing is easy to machine and has excellent wear resistance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The process gas first passes through the compressor suction port 1 and is compressed by the compressor wheel 2. The diffuser 3 provided at the outlet of the compressor wheel 2 efficiently converts velocity energy into pressure. Further, the process gas is discharged from the compressor outlet 4, cooled by the heat exchanger 5, and then guided to the turbine inlet 6, passes through the nozzle 7, and is adiabatically expanded by the turbine impeller 8 to become a low-temperature low-pressure process gas. leak.

Further, labyrinths 9 are installed on the back surfaces of the compressor impeller 2 and the turbine impeller 8 to separate the compressor chamber, the turbine chamber and the bearing chamber 10. The power generated during the adiabatic expansion of the turbine impeller 8 is generated by the shaft 11
Is transmitted to the compressor impeller 2 and the process gas is adiabatically compressed. The shaft 11 is supported by a dynamic pressure gas journal bearing 12 and a dynamic pressure gas thrust bearing 20.
The dynamic pressure gas thrust bearing 20 includes a thrust collar 13 integrated with the shaft 11 and the thrust collar 13 thereof.
The thrust bearing 14 has a sandwich structure in which spiral grooves are formed at both ends of the material, such as SUS, Cu, or Al, which is easily processed.

FIG. 2 shows a detailed view of the thrust bearing 14.
The spiral groove 15 is arranged in a logarithmic spiral shape from the outer circumference of the thrust bearing 14 toward the seal surface 16 (this drawing is an example in the case of 9 grooves). The state of the bottom in the groove direction is
As shown in FIG. 3, the groove is inclined with respect to the rotation direction so that the groove depth becomes small, and the surface thereof is subjected to surface modification or film formation by an ion source, and a layer 17 having improved wear resistance is provided. .

Next, the specific operation of the turbine compressor having the above-mentioned components will be described.

For example, when the compressor is used with a vertical shaft with the compressor side facing downward as shown in FIG. 1, the thrust collar 13 and the thrust bearing 14 are in solid contact with each other and are stationary. In this state, when the process gas discharged from the compressor is supplied to the turbine side, the turbine impeller 8 rotates, while the compressor is started by the turbine power, and the thrust force acts from the compressor side to the turbine side. By the thrust force, the thrust collar 13 and the upper thrust bearing 1
4 approaches, and the bearing chamber 1
The gas in 0 is sucked toward the inner peripheral side to increase the pressure in the spiral groove 15, and the rotor (shaft 11, thrust collar 1
3 and the shaft 11 on both ends of which the turbine impeller 8 and the compressor impeller 2 are installed). At this time, since the bottom surface of the spiral groove 15 is inclined so as to be narrow in the rotation direction, the load capacity generated by the spiral groove 15 and the wedge-shaped gap existing in the rotation direction make the bearing load capacity 2 to 3 times that of the spiral unit. Increase relatively. The rotating body involves some solid contact in the initial floating stage, and the thrust force and the bearing load capacity are balanced at a predetermined rotation speed to maintain a predetermined clearance. Further, at the time of stoppage, contrary to the above, the gas supply to the turbine side is stopped, so that the rotation speed is reduced and the thrust force and the bearing load capacity are reduced. Therefore, the thrust collar 13 and the lower thrust bearing 14 are stopped together with solid contact. However, abrasion or seizure caused by solid contact at the time of starting or stopping can be prevented because the surface of the thrust bearing is surface-modified or film-formed by an ion source to improve abrasion resistance.

4 and 5 show the state of the bottom surface in the groove direction of the spiral groove according to another embodiment of the present invention. 18 is a stepped bottom surface in which the groove depth decreases stepwise with respect to the rotation direction,
Similarly, 19 is a stepped inclined surface in which the groove depth becomes smaller due to a step and an inclination from the middle. Both of the present embodiments have the same effect as the example shown in FIG.

[0015]

According to the present invention, the range of application of the turbine compressor can be expanded by improving the load capacity, and the unnecessary pipe or oil supply device can be eliminated to achieve compactness, cost reduction and cleanliness. In addition, since this bearing uses the base material of the thrust bearing as a material that can be easily processed, it is possible to easily manufacture bearings with complicated shapes, and the surface of the thrust bearing or the opposing surface or both of them can be surface modified by an ion source. Because of the thin film formation, it is possible to obtain a bearing that is easy to machine and has excellent wear resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dynamic pressure gas bearing type turbine compressor to which an embodiment of the present invention is applied.

FIG. 2 is a detailed plan view of a dynamic pressure gas thrust bearing showing an embodiment of the present invention.

3 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 4 is a cross-sectional view showing another embodiment of the bottom surface in the groove direction.

FIG. 5 is a sectional view showing a groove-direction bottom surface state of yet another embodiment.

[Explanation of symbols]

1 ... Compressor suction port, 2 ... Compressor wheel, 3
... Diffuser, 4 ... Compressor outlet, 5 ... Heat exchanger, 6 ... Turbine inlet, 7 ... Nozzle, 8 ... Turbine impeller, 9 ... Labyrinth, 10 ... Bearing chamber, 11 ... Shaft,
12 ... Dynamic pressure gas journal bearing, 13 ... Thrust collar, 14 ... Thrust bearing, 15 ... Spiral groove, 16 ...
Sealing surface, 17 ... Layer, 18 ... Stepped bottom surface, 19 ... Stepped inclined surface, 20 ... Dynamic pressure gas thrust bearing.

Claims (1)

[Claims] 1. A rotary body having a turbine impeller for adiabatically expanding high-pressure gas at one end and a compressor impeller for adiabatically compressing gas by the power generated by the turbine impeller at the other end as a dynamic pressure gas journal bearing and In a turbine compressor supported by a dynamic pressure gas thrust bearing, the base material of the dynamic pressure gas thrust bearing is a material that can be easily processed, and the bearing shape is a spiral type, and the bottom of the spiral type groove is narrowed in the rotation direction. A dynamic pressure gas thrust bearing for a turbine compressor, wherein the thrust bearing surface or the opposing surface or both are inclined or stepped or both, and surface modification or film formation is performed by an ion source.