JP2017008775A - Expansion turbine device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress seal leakage of a low temperature gas in an expansion turbine device having a static pressure gas bearing.SOLUTION: An expansion turbine device 1 includes: a body 10; a turbine impeller 11; a brake impeller 12; a rotating shaft 13; static pressure gas bearings 14a-14d; a first labyrinth seal 30; an exhaust line (mixed gas discharging passage) 18 for discharging mixed gas of bearing gas discharged from the first radial static pressure bearing 14d and refrigerant gas leaked from an expansion chamber through the first labyrinth seal 30; a first back pressure adjusting valve 80; a temperature sensor 60 for measuring a temperature of the mixed gas flowing through the exhaust line (mixed gas discharging passage) 18; and a control device 90 for controlling the first back pressure adjusting valve 80 so as to increase a pressure of the exhaust line 18 when a temperature of the mixed gas is lowered.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an expansion turbine device, and more particularly to a leakage prevention technique for an expansion turbine device including a static pressure gas bearing.

  Generally, a liquefaction system for liquefying a source gas such as hydrogen gas or helium gas includes a feed line for sending the source gas, a refrigerant circulation line for circulating the refrigerant gas, and a heat exchanger for cooling the source gas with the refrigerant. Yes. The refrigerant gas circulating in the refrigerant circulation line is compressed by the compressor, then adiabatically expanded by the expansion turbine, and the temperature is lowered. The raw material gas is cooled by exchanging heat with the cooled refrigerant gas in the heat exchanger.

  The expansion turbine needs a bearing for supporting the rotating shaft. If a liquid bearing using lubricating oil is applied as the bearing, the lubricating oil may be mixed into the refrigerant gas passing through the expansion turbine. Therefore, it is preferable to apply a gas bearing using the same type of gas as the refrigerant gas to the bearing. Of the gas bearings, static pressure gas bearings can suppress friction between the bearing surface and the rotating shaft at the time of starting and stopping the liquefaction system, and are suitable for ultra-high speed rotation. For this reason, static pressure gas bearings are used as bearings for expansion turbines (see, for example, Patent Document 1).

  An expansion turbine using a static pressure gas bearing includes a bearing supply line for supplying a bearing gas of the same type as the refrigerant gas to the static pressure gas bearing, and a bearing exhaust line for exhausting the bearing gas that has passed through the static pressure gas bearing. . A rotation shaft is inserted into a bearing chamber inside the expansion turbine, and a bearing supply line and a bearing exhaust line are communicated with each other. A turbine impeller provided at one end of the rotating shaft is accommodated in the expansion chamber. In the expansion chamber, an expansion chamber inlet into which refrigerant gas flows is formed on the outer peripheral side of the turbine impeller, and an expansion chamber outlet from which refrigerant gas flows out is formed in the central axis direction. On the other hand, the brake impeller provided at the other end of the rotating shaft is accommodated in the braking gas chamber. In the braking gas chamber, a communication path that connects the outlet and the inlet of the braking gas chamber is formed, and a closed circuit including a brake impeller is formed.

  A labyrinth seal is provided on the rear surface of the turbine impeller of the expansion turbine in order to prevent low-temperature refrigerant gas from leaking from the expansion chamber to the bearing chamber (see, for example, Patent Document 2).

JP 2000-55050 A JP-A-6-26301

  However, since the labyrinth seal has a certain gap with the rotating shaft, the leakage cannot be completely prevented as long as there is a differential pressure of the seal. When the leakage of low-temperature gas from the expansion chamber to the bearing chamber increases, the efficiency of the expansion turbine decreases, and the bearing chamber is cooled, so that the clearance between the rotating shaft and the radial hydrostatic bearing changes, and in some cases it rotates. Contact between the shaft and the radial hydrostatic bearing occurs.

  Then, an object of this invention is to suppress the seal | sticker leakage of a low temperature gas in an expansion turbine provided with a static pressure gas bearing.

  An expansion turbine apparatus according to an aspect of the present invention has an expansion chamber, a braking gas chamber, and a shaft insertion hole formed therein, and the shaft insertion hole communicates the expansion chamber and the braking gas chamber and has a rotating shaft. Is inserted into the main body, the turbine impeller accommodated in the expansion chamber and expands the refrigerant gas, and the brake accommodated in the braking gas chamber and braked by the same type of braking gas as the refrigerant gas. An impeller, the shaft insertion hole with a gap between them, the turbine impeller provided at one end, the rotation shaft provided with the brake impeller at the other end, and the shaft insertion hole A static pressure gas bearing that is provided at the inlet and is rotatably supported by the static pressure of a bearing gas of the same type as the refrigerant gas that is supplied from the outlet and discharged from the outlet; and on the expansion chamber side of the bearing chamber end Mixing of a first labyrinth seal provided in a portion between the portion provided with the hydrostatic gas bearing, and a refrigerant gas leaking from the expansion chamber to the bearing chamber through the bearing gas and the first labyrinth seal A mixed gas discharge path for discharging gas; a first back pressure adjusting valve for adjusting a back pressure of the static pressure gas bearing; provided in the mixed gas discharge path; provided in the mixed gas discharge path; And a control device for controlling the first back pressure regulating valve so as to increase the back pressure of the static pressure gas bearing when the temperature of the mixed gas flowing through the mixed gas discharge path decreases. And comprising.

  According to the above configuration, when the refrigerant gas leaking from the expansion chamber to the bearing chamber through the first labyrinth seal increases, the temperature of the mixed gas flowing through the mixed gas discharge path decreases. Increase back pressure of pressurized gas bearing. Thereby, since the differential pressure | voltage of a 1st labyrinth seal becomes small, the amount of leaks can be controlled.

  In the above-described expansion turbine apparatus, the static pressure gas bearing includes first and second radial hydrostatic bearings that support the rotary shaft so as to be rotatable in the radial direction, and a thrust static bearing that supports the rotary shaft so as to be rotatable in the axial direction. The first radial hydrostatic bearing, the thrust hydrostatic bearing, and the second radial hydrostatic bearing are sequentially located in the bearing chamber from the expansion chamber toward the braking gas chamber. And the first labyrinth seal is provided at a portion between the end of the bearing chamber on the expansion chamber side and the portion where the first radial hydrostatic bearing is provided, and the first radial static seal is provided. The upstream end of the mixed gas discharge path may be connected to the outlet of the pressure bearing, and the upstream end of the dedicated bearing gas discharge path may be connected to the outlet of the thrust hydrostatic bearing and the outlet of the second radial hydrostatic bearing.

  According to the above configuration, the back pressure control independent of the other bearings is performed only on the first radial hydrostatic bearing located on the expansion chamber side. Back pressure control may have the adverse effect of reducing bearing performance if the back pressure is increased too much. However, according to the above configuration, only the first radial hydrostatic bearing on the expansion chamber side adjacent to the first labyrinth seal is controlled. Therefore, the purpose can be achieved, and the degree of freedom in setting the back pressure of other bearings is increased, so that suitable control can be realized.

  In the above-described expansion turbine apparatus, the static pressure gas bearing includes first and second radial hydrostatic bearings that rotatably support the rotary shaft in the radial direction, and a thrust static shaft that rotatably supports the rotary shaft in the axial direction. The first radial hydrostatic bearing, the thrust hydrostatic bearing, and the second radial hydrostatic bearing are sequentially located in the bearing chamber from the expansion chamber toward the braking gas chamber. And a second labyrinth seal provided in a portion of the bearing chamber between the first radial hydrostatic bearing and the thrust hydrostatic bearing, an outlet of the thrust hydrostatic bearing, and the second A dedicated exhaust for the bearing gas, whose upstream end is connected to the outlet of the radial hydrostatic bearing, and a dedicated exhaust for the bearing gas, which adjust the back pressure of the thrust hydrostatic bearing and the second radial hydrostatic bearing. A second back pressure regulating valve, one end connected to the outlet of the braking gas chamber, the other end connected to the inlet of the braking gas chamber, one end connected to the braking line, and And a ventilation path having the other end connected to the bearing gas dedicated discharge path.

  According to the above configuration, the pressure of the braking line and the back pressure of the thrust hydrostatic bearing and the second radial hydrostatic bearing are made uniform through the ventilation path, independent of the bearing back pressure of the first radial hydrostatic bearing. Pressure control can be performed. Furthermore, according to the said structure, the distance between a 2nd radial hydrostatic bearing and an expansion chamber can be shortened by moving a 2nd labyrinth seal between a 1st radial hydrostatic bearing and a thrust hydrostatic bearing. It is possible to reduce the axial length of the rotary shaft from the second radial hydrostatic bearing to the expansion chamber side, thereby reducing the mass of the rotating body and improving the vibration stability.

  In the expansion turbine apparatus, the static pressure gas bearing includes first and second radial hydrostatic bearings that rotatably support the rotating shaft in a radial direction, and a thrust static bearing that rotatably supports the rotating shaft in an axial direction. The first radial hydrostatic bearing, the thrust hydrostatic bearing, and the second radial hydrostatic bearing are sequentially located in the bearing chamber from the expansion chamber toward the braking gas chamber. And the first labyrinth seal is provided at a portion between the end of the bearing chamber on the expansion chamber side and the portion where the first radial hydrostatic bearing is provided, and the first radial static seal is provided. An upstream end of the mixed gas discharge path is connected to an outlet on the expansion chamber side of the pressure bearing, an outlet on the braking gas chamber side of the first radial hydrostatic bearing, an outlet of the thrust hydrostatic bearing, and the second radial Static pressure The upstream end of the bearing gas only discharge path to receive the outlet may be connected.

  According to the above configuration, since the back pressure control is performed only on the expansion chamber side outlet of the first radial hydrostatic bearing closest to the first labyrinth seal, the degree of freedom in setting the back pressure is increased and suitable control is performed. Can be realized.

  ADVANTAGE OF THE INVENTION According to this invention, the seal leak of a low temperature gas can be suppressed in an expansion turbine apparatus provided with a static pressure gas bearing. Thereby, the efficiency fall of a turbine and the cooling of a bearing chamber can be suppressed.

It is a partial cross section figure which shows the structure of the expansion turbine apparatus which concerns on 1st Embodiment. It is the schematic which shows the structure of the radial hydrostatic bearing of FIG. It is the schematic which shows the structure of the thrust hydrostatic bearing of FIG. It is a schematic diagram which shows the structure of the labyrinth seal of FIG. It is the schematic which shows the whole structure of the expansion turbine apparatus of FIG. It is a schematic diagram which shows the structure of the expansion turbine apparatus which concerns on 2nd Embodiment. It is a schematic diagram which shows the structure of the expansion turbine apparatus which concerns on 3rd Embodiment. It is a schematic diagram which shows the structure of the expansion turbine apparatus which concerns on 4th Embodiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. Below, the same code | symbol is attached | subjected to the element which is the same or it corresponds through all the drawings, and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a partial cross-sectional view showing the structure of the expansion turbine apparatus according to the first embodiment. As shown in FIG. 1, the expansion turbine device 1 has an expansion chamber 21, a braking gas chamber 20, and a shaft insertion hole 22 formed in the main body 10. The main body 10 is formed in a casing shape, for example. The shaft insertion hole 22 is formed so that the expansion chamber 21 and the braking gas chamber 20 communicate with each other and the rotation shaft 13 can be inserted.

  The rotary shaft 13 is inserted into the shaft insertion hole 22 with a gap, the turbine impeller 11 is provided at one end, and the brake impeller 12 is provided at the other end. The rotary shaft 13 extends in the vertical direction within the main body 10 and is supported so as to be rotatable about the vertical axis.

  The turbine impeller 11 is accommodated in the expansion chamber 21 and configured to expand the refrigerant gas. The turbine impeller 11 is formed at the lower end of the rotating shaft 13. An expansion chamber inlet 24 and an expansion chamber outlet 26 are formed in the lower part of the main body 10, and thereby the expansion chamber 21 that houses the turbine impeller 11 communicates with the turbine line 16 outside the main body 10. The refrigerant that has flowed into the expansion chamber inlet 24 from the turbine line 16 is injected toward the turbine impeller 11. The refrigerant gas expands and cools down as the turbine impeller 11 rotates, and then flows out of the main body 10 from the expansion chamber outlet 26.

  The brake impeller 12 is housed in the braking gas chamber 20 and is braked by the same type of braking gas as the refrigerant gas. The brake impeller 12 is formed at the upper end of the rotating shaft 13. A brake gas chamber inlet 27 and a brake gas chamber outlet 29 are formed in the upper portion of the main body 10, and thereby the brake gas chamber 20 accommodating the brake impeller 12 communicates with the brake line 15 outside the main body 10. The normal-temperature braking gas that has flowed into the braking gas chamber inlet 27 from the braking line 15 flows directly toward the brake impeller 12. The braking gas is compressed along with the rotation of the brake impeller 12 to increase in pressure and temperature, and then returns from the braking gas chamber outlet 29 to the braking gas chamber inlet 27 through the braking line 15.

  The static pressure gas bearing 14 is provided in a bearing chamber 23 formed in the shaft insertion hole 22, and static pressure gas bearing 14 of the same type as the refrigerant gas supplied from the expansion chamber inlet 24 and discharged from the expansion chamber outlet 26. The rotating shaft 13 is rotatably supported by the pressure. The static pressure gas bearing 14 includes radial static pressure bearings 14a and 14d that support the rotary shaft 13 rotatably in the radial direction, and thrust static pressure bearings 14b and 14c that support the rotary shaft 13 rotatably in the axial direction. . These static pressure gas bearings 14 a to 14 d are formed in a substantially cylindrical shape and are provided so as to surround the outer peripheral side of the rotating shaft 13. The first radial hydrostatic bearing 14d, the first thrust hydrostatic bearing 14c, the second thrust hydrostatic bearing 14b, and the radial hydrostatic bearing 14a are sequentially located in the bearing chamber 23 from the expansion chamber 21 toward the braking gas chamber 20. It is provided as follows. The second thrust hydrostatic bearing 14b and the first thrust hydrostatic bearing 14c are arranged so as to sandwich the thrust collar 34 protruding in the radial direction from the upper and lower central portion of the rotating shaft 13 in the vertical direction.

  In the main body 10, a first common supply passage 35a, a second common supply passage 35b, and a common exhaust passage 36 are formed. The first common supply passage 35a, the second common supply passage 35b, and the common exhaust passage 36 are formed at different positions in the circumferential direction. The first common air supply passage 35a communicates with the bearing gas inlet 49, and is a passage through which the bearing gas supplied to the gap between the second radial hydrostatic bearing 14a and the first radial hydrostatic bearing 14d flows. The two common air supply passages 35b communicate with the bearing gas inlet 49 and are passages through which the bearing gas supplied to the gap between the second thrust hydrostatic bearing 14b and the first thrust hydrostatic bearing 14c flows. In the present embodiment, the first common supply passage 35a and the second common supply passage 35b are configured independently, but may be configured in common. The common exhaust passage 36 communicates with the bearing gas outlet 50 and is a passage through which the bearing gas discharged from the gaps between the static pressure gas bearings 14a to 14d flows.

  The first common supply passage 35 a is branched into a first supply passage 37 and a second supply passage 38. The second common supply passage 35 b is branched into a third supply passage 43 and a fourth supply passage 44. The first air supply passage 37 is a passage through which the bearing gas supplied to the gap of the second radial hydrostatic bearing 14a flows. The second air supply passage 38 is a passage through which the bearing gas supplied to the gap of the first radial hydrostatic bearing 14d flows. The third air supply passage 43 is a passage through which the bearing gas supplied to the gap of the second thrust hydrostatic bearing 14b flows. The fourth air supply passage 44 is a passage through which the bearing gas supplied to the gap of the first thrust hydrostatic bearing 14c flows.

  The common exhaust passage 36 communicates with the first exhaust passage 39, the second exhaust passage 40, the third exhaust passage 41, and the fourth exhaust passage 42. The first exhaust passage 39 is a passage through which the bearing gas discharged upward from the clearance of the second radial hydrostatic bearing 14a flows. The second exhaust passage 40 is a passage through which the bearing gas discharged downward from the gap of the second radial hydrostatic bearing 14a and the bearing gas discharged upward from the gap of the second thrust hydrostatic bearing 14b flow. The third exhaust passage 41 is a passage through which the bearing gas discharged downward from the clearance of the first thrust hydrostatic bearing 14c and the bearing gas discharged upward from the clearance of the first radial hydrostatic bearing 14d flow. The fourth exhaust passage 42 is a passage through which the bearing gas discharged downward from the clearance of the first radial hydrostatic bearing 14d flows, and the fourth exhaust passage 42 passes from the expansion chamber 21 through the first labyrinth seal 30. The refrigerant gas leaking into the bearing chamber 23 of the first radial hydrostatic bearing 14d flows.

  FIG. 2 schematically shows a cross-sectional view of the first radial hydrostatic bearing 14d. As shown in FIG. 2, a bearing member 51 is formed in a substantially cylindrical shape so as to surround the outer peripheral side of the rotating shaft 13. The bearing member 51 has a gap with the rotary shaft 13. A plurality of nozzle holes (bearing inlets) 51 a are formed in the bearing member 51 in the circumferential direction. The bearing gas flowing through the second air supply passage 38 branched from the first common air supply passage 35a in FIG. 1 is injected to the rotary shaft 13 from the nozzle hole 51a. A bearing film (dotted line) of the first radial hydrostatic bearing 14 d is formed between the inner peripheral surface of the bearing member 51 and the outer peripheral surface of the rotary shaft 13. The bearing gas (dotted arrow) discharged upward from one end (bearing outlet) of the gap of the first radial hydrostatic bearing 14d is discharged from the third exhaust passage 41 of FIG. The bearing gas (dotted arrow) discharged downward from the other end (bearing outlet) of the clearance of the first radial hydrostatic bearing 14d is discharged from the fourth exhaust passage 42 of FIG. 1 through the common exhaust passage 36. The second radial hydrostatic bearing 14a in FIG. 1 also has the same configuration as the first radial hydrostatic bearing 14d, a bearing film is formed by bearing gas, and both ends of the gap (bearing outlet) of the second radial hydrostatic bearing 14a are formed. The bearing gas discharged from the upper and lower sides is guided to the common exhaust passage 36 through the first exhaust passage 39 and the second exhaust passage 40.

  FIG. 3 schematically shows a cross-sectional view of the thrust hydrostatic bearings 14b and 14c. As shown in FIG. 3, the rotating shaft 13 and the thrust collar 34 are arranged with a gap inside the main body 10. Here, the third air supply passage 43 is a passage branched from the second common air supply passage 35b of FIG. 1 and through which the bearing gas supplied to the gap of the second thrust hydrostatic bearing 14b flows. The fourth air supply passage 44 is a passage that branches from the second common air supply passage 35b and through which the bearing gas supplied to the gap of the first thrust hydrostatic bearing 14c flows.

  The bearing gas flowing through the third air supply passage 43 is injected from the nozzle hole (bearing inlet) 43a, and the bearing film (dotted line) of the second thrust hydrostatic bearing 14b is connected to the lower end surface of the inner wall 22a of the shaft insertion hole 22 and the thrust collar. 34 is formed between the upper end surface of 34. The bearing gas flowing through the fourth air supply passage 44 is injected from the nozzle hole 44 a, and the bearing film (dotted line) of the first thrust hydrostatic bearing 14 c is connected to the upper end surface of the inner wall 22 a of the shaft insertion hole 22 and the lower end surface of the thrust collar 34. Formed between. The bearing gas (dotted arrow) discharged upward from one end (bearing outlet) of the gap of the second thrust hydrostatic bearing 14b is discharged from the second exhaust passage 40 of FIG. The bearing gas (dotted arrow) discharged downward from the other end (bearing outlet) of the clearance of the first thrust hydrostatic bearing 14c is discharged from the third exhaust passage 41 of FIG. 1 through the common exhaust passage 36. The bearing gas (dotted arrow) that flows downward from one end (bearing outlet) of the gap of the second thrust hydrostatic bearing 14b and the upper side from the other end (bearing outlet) of the bearing gap of the first thrust hydrostatic bearing 14c. The bearing gas that has flowed out (dotted line arrow) is also discharged through the common exhaust passage 36.

  The main body 10 of FIG. 1 has a bearing gas inlet 49 and a bearing gas outlet 50. The bearing gas inlet 49 communicates with the first common supply passage 35a and the second common supply passage 35b. The bearing gas outlet 50 communicates with the common exhaust passage 36. A bearing gas is supplied from the bearing gas inlet 49 to the static pressure gas bearings 14 a to 14 d in the main body 10 of the expansion turbine device 1. The same type of gas as the refrigerant gas is used for the bearing gas. By supplying bearing gas to the gaps between the static pressure gas bearings 14a to 14d, the rotary shaft 13 can be rotatably supported in the main body 10, and the radial load and thrust load of the rotary shaft 13 can be favorably supported. be able to. At the time of starting and stopping, there is no friction between the outer peripheral surface of the rotating shaft 13 and the inner peripheral surfaces of the static pressure gas bearings 14a to 14d. For this reason, the lifetime of the expansion turbine apparatus 1 can be extended.

  A first labyrinth seal 30 is provided at a portion between the end of the bearing chamber 23 on the expansion chamber 21 side and a portion where the first radial hydrostatic bearing 14d is provided (see FIG. 1). FIG. 4 is a schematic diagram showing the configuration of the first labyrinth seal 30. As shown in FIG. 4, the first labyrinth seal 30 has an inner peripheral surface that surrounds the outer peripheral side of the rotary shaft 13 with a certain distance from the rotary shaft 13. A plurality of concave and convex gaps are provided on the inner peripheral surface. Each time the refrigerant enters the gap, the leakage pressure gradually decreases. The refrigerant leakage between the cryogenic refrigerant gas and the bearing gas which are adiabatically expanded in the expansion chamber 21 is suppressed. A second labyrinth seal 31 having a similar structure is also provided at a portion between the end on the braking gas chamber 20 side and the portion where the second radial hydrostatic bearing 14a is provided (see FIG. 1). The leakage of the refrigerant between the braking gas and the bearing gas in the braking gas chamber 20 is suppressed.

  FIG. 5 is a schematic diagram showing an overall configuration of the expansion turbine apparatus 1 of FIG. In the following, description of the already described configuration is omitted. As shown in FIG. 5, the expansion turbine apparatus 1 includes a main body 10, a braking line 15, a turbine line 16, a bearing supply line 17, an exhaust line 18, a temperature sensor 60, and a first back pressure adjustment valve 80. And a control device 90.

  The braking line 15 is a pipe for circulating the braking gas and supplying the braking gas to the brake impeller 12. One end of the brake line 15 is connected to the brake gas chamber inlet 27 of the brake gas chamber 20 of FIG. 1, and the other end of the brake line 15 is connected to the brake gas chamber outlet 29 of the brake gas chamber 20. A heat exchanger 53 is provided in the middle of the braking line 15.

  The heat exchanger 53 lowers and lowers the pressure of the braking gas circulating in the braking line 15. In addition, the braking gas circulating in the braking line 15 is compressed and raised in temperature and raised in the process of passing through the brake impeller 12, but lowered and lowered in pressure as it passes through the heat exchanger 53.

  The turbine line 16 is a pipe for supplying refrigerant gas to the turbine impeller 11. One end of the turbine line 16 is connected to the expansion chamber inlet 24 of the expansion chamber 21 in FIG. 1, and the other end of the turbine line 16 is connected to the expansion chamber outlet 26 of the expansion chamber 21. The low-temperature and high-pressure refrigerant compressed by a compressor (not shown) is introduced to the turbine impeller 11 upstream of the expansion chamber inlet 24 of the expansion chamber 21. The turbine impeller 11 lowers the temperature and pressure of the low-temperature and high-pressure refrigerant by adiabatic expansion.

  The bearing supply line 17 is configured to supply bearing gas to the static pressure gas bearings 14a to 14d. One end of the bearing supply line 17 is connected to, for example, a feed line that feeds the raw material gas of the liquefaction system, and the other end of the bearing supply line 17 is connected to a bearing gas inlet 49 of the main body 10 (see FIG. 1). The bearing supply line 17 supplies bearing gas to each of the second radial hydrostatic bearing 14a, the second thrust hydrostatic bearing 14b, the first thrust hydrostatic bearing 14c, and the first radial hydrostatic bearing 14d. It is configured. The bearing supply line 17 communicates with the first common air supply passage 35a and the second common air supply passage 25b in FIG. Bearing gas is supplied to the second radial hydrostatic bearing 14a and the first radial hydrostatic bearing 14d through the first air supply passage 37 and the second air supply passage 38 branched from the first common air supply passage 35a. The bearing gas is supplied to the first thrust hydrostatic bearing 14c and the second thrust hydrostatic bearing 14b through the third supply passage 43 and the fourth supply passage 44 branched from the supply passage 35b (see FIG. 1). .

  The exhaust line 18 has an upstream end connected to the outlets of the bearing chambers 23 of the static pressure gas bearings 14a to 14d, and discharges the bearing gas that has passed through the static pressure gas bearings 14a to 14d. In the present embodiment, the upstream end of the exhaust line 18 is connected to the bearing gas outlet 50 of FIG. The exhaust line 18 includes a first exhaust passage 39, a second exhaust passage 40, a third exhaust passage 41, a fourth exhaust passage 42, and a common exhaust passage 36 in FIG. 1 (see FIG. 1). The exhaust line 18 is used for bearing gas that has passed through the static pressure gas bearings 14 a to 14 d and refrigerant gas that leaks from the turbine line 16 (expansion chamber) to the bearing chamber 23 of the first radial static pressure bearing 14 d through the first labyrinth seal 30. A mixed gas discharge path configured to discharge the mixed gas.

The temperature sensor 60 is provided in the exhaust line 18 and is configured to measure a bearing exhaust temperature T ₁ of the exhaust line 18. The temperature sensor 60 is configured to output the measured temperature information to the control device 90.

  The first back pressure adjustment valve 80 is provided in the exhaust line 18 and is configured to adjust the back pressure of the exhaust line 18 based on a command from the control device 90.

The control device 90 is provided in the exhaust line 18 and controls the opening and closing of the first back pressure regulating valve 80 based on the bearing exhaust temperature T ₁ measured by the temperature sensor 60. In the present embodiment, the control device 90 has a function of controlling not only the expansion turbine device 1 but also other devices such as a compressor. The control device 90 is, for example, a microcomputer mainly composed of a CPU, a ROM, and an input / output interface. Process data such as measured values of the pressure and temperature of the exhaust line 18, turbine rotational speed, and the like are input to the input side of the control device 90. A first back pressure adjusting valve 80, a supply valve, a discharge valve, and the like are connected to the output side of the control device 90. The CPU executes a control program stored in the ROM. The CPU controls the first back pressure regulating valve 80 so as to obtain the bearing back pressure as set while monitoring the temperature measurement value of the process data. The control device 90, when the bearing exhaust temperatures T ₁ is lower than the reference value T _S, is controlled so as to increase the bearing back pressure P _1. Here reference temperature T _S is the value of a predetermined value or a predetermined range in a normal.

Next, operation | movement of the expansion turbine apparatus 1 of the above structures is demonstrated using FIG. The expansion turbine device 1 rotates at an ultra high speed by a low-temperature and high-pressure refrigerant supplied through the turbine line 16. During operation of the expansion turbine device 1, bearing gas is supplied from the bearing supply line 17 to the gaps between the static pressure gas bearings 14 a to 14 d of the turbine body 10. Thereby, the rotating shaft 13 is rotatably supported in the main body 10, and the radial load and the thrust load of the rotating shaft 13 are supported. From the exhaust line 18, the bearing gases of the static pressure gas bearings 14a to 14d are discharged. A first labyrinth seal 30 is provided at a portion between an end of the bearing chamber 23 in which the turbine impeller 11 is accommodated on the expansion chamber 21 side and a portion where the first radial hydrostatic bearing 14d is provided. There is refrigerant gas leaking from the turbine line 16 (expansion chamber) to the bearing chamber 23 through the 1 labyrinth seal 30. For this reason, the exhaust line 18 contains a mixed gas of the bearing gas and the leaked refrigerant gas. When the refrigerant gas leaked from the turbine line 16 (expansion chamber) to the bearing chamber 23 through the first labyrinth seal 30 increases, the temperature of the exhaust line 18 measured by the temperature sensor 60 decreases. As the differential pressure of the first labyrinth seal 30 increases, the amount of leakage increases. Sensor installation is difficult at the inlet or outlet of the first labyrinth seal 30, and accurate pressure measurement is difficult. Therefore, the control device 90, when the bearing exhaust temperature T ₁ of the exhaust line 18 is lower than the reference value T _S, is controlled so as to increase the bearing back pressure P _1. Thereby, since the differential pressure | voltage of the 1st labyrinth seal 30 becomes small, the amount of leaks can be controlled.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. Below, the description of the structure common to 1st Embodiment is abbreviate | omitted, and only a different structure is demonstrated.

  FIG. 6 is a schematic diagram illustrating a configuration of an expansion turbine apparatus 1A according to the second embodiment. As shown in FIG. 6, in the expansion turbine apparatus 1A, the upstream end of the exhaust line (mixed gas discharge path) 18 is connected to the outlet of the first radial hydrostatic bearing 14d as compared with the first embodiment (FIG. 5). The upstream end of the bearing exhaust line (bearing gas exclusive discharge path) 18a is connected to the outlet of the first thrust hydrostatic bearing 14c and the second thrust hydrostatic bearing 14b and the outlet of the second radial hydrostatic bearing 14a. Is different. The exhaust line 18 is configured to discharge the bearing gas that has passed through the first radial hydrostatic bearing 14d. The bearing exhaust line 18a is configured to discharge the bearing gas that has passed through the thrust hydrostatic bearings 14b and 14c and the second radial hydrostatic bearing 14a. In the present embodiment, the downstream end of the bearing exhaust line 18 a is configured to merge in the middle of the exhaust line 18. A third labyrinth seal 32 is provided in a portion between the first radial hydrostatic bearing 14d and the first thrust hydrostatic bearing 14c.

  Further, in the present embodiment, a temperature sensor 60 and a first back pressure adjustment valve 80 are provided in the exhaust line 18. A pressure sensor 100 and a second back pressure regulating valve 110 are provided in the bearing exhaust line 18a. Pressure control of the static pressure gas bearings 14a, 14b, and 14c is performed by the pressure sensor 100 and the second back pressure regulating valve 110. Further, back pressure control independent of the other static pressure gas bearings 14a, 14b, and 14c is performed only on the first radial static pressure bearing 14d located on the expansion chamber 21 side. The back pressure control may have a harmful effect that the bearing performance deteriorates if the back pressure is increased too much. However, according to this embodiment, the first radial hydrostatic bearing 14d on the expansion chamber 21 side adjacent to the first labyrinth seal 30 is used. The purpose can be achieved by controlling only the pressure, and the degree of freedom in setting the back pressure of the other static pressure gas bearings 14a, 14b, 14c is increased, and suitable control can be realized.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG. In the following, description of the configuration common to the above embodiment will be omitted, and only the configuration that is different will be described.

  FIG. 7 is a schematic diagram showing a configuration of an expansion turbine apparatus 1B according to the third embodiment. As shown in FIG. 7, the expansion turbine apparatus 1B has a second labyrinth seal 31 between the first radial hydrostatic bearing 14d and the first thrust hydrostatic bearing 14c, as compared with the first embodiment (FIG. 5). It is provided in the part. The upstream end of the exhaust line (mixed gas discharge path) 18 is connected to the outlet of the first radial hydrostatic bearing 14d, the outlets of the first thrust hydrostatic bearing 14c and the second thrust hydrostatic bearing 14b, and the second radial hydrostatic bearing. The upstream end of a bearing exhaust line (bearing gas exclusive discharge path) 18a is connected to the outlet 14a. Further, a pressure sensor 100 and a second back pressure adjusting valve 110 are provided in the bearing exhaust line 18a. The present embodiment is different in that it further includes a ventilation path 15b having one end connected to the brake line 15 and the other end connected to the bearing exhaust line 18a.

  According to the above configuration, in addition to the effects of the second embodiment, the pressure of the braking line 15 and the back pressure of the thrust hydrostatic bearings 14b and 14c and the second radial hydrostatic bearing 14a are made uniform via the ventilation path 15b. The pressure can be controlled by the pressure sensor 100 and the second back pressure regulating valve 110.

  Further, according to the above configuration, the second labyrinth seal 31 is moved between the first radial hydrostatic bearing 14d and the thrust hydrostatic bearing 14c, so that the distance between the second radial hydrostatic bearing 14a and the expansion chamber 21 is increased. The axial length of the rotary shaft 13 from the second radial hydrostatic bearing 14a to the expansion chamber 21 side can be shortened, and the mass of the rotary body can be reduced and the vibration stability can be improved. .

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG. In the following, description of the configuration common to the above embodiment will be omitted, and only the configuration that is different will be described.

  FIG. 8 is a block diagram showing a configuration of an expansion turbine apparatus 1C according to the fourth embodiment. As shown in FIG. 8, in the expansion turbine apparatus 1C, the upstream end of the exhaust line 18 is connected only to the outlet on the expansion chamber side of the first radial hydrostatic bearing 14d, as compared with the first embodiment (FIG. 5). And the upstream end of the bearing exhaust line 18a are connected to the outlet on the braking gas chamber side of the first radial hydrostatic bearing 14d, the outlets of the thrust hydrostatic bearings 14b and 14c, and the outlet of the second radial hydrostatic bearing 14a. Is different. The exhaust line 18 discharges the mixed gas of the bearing gas discharged from the clearance of the first radial hydrostatic bearing 14 d to the expansion chamber side and the refrigerant gas leaking from the expansion chamber 21 to the bearing chamber 23 through the first labyrinth seal 30. .

  According to the above configuration, since the back pressure control is performed only on the outlet on the expansion chamber side of the first radial hydrostatic bearing 14d closest to the first labyrinth seal 30, a countermeasure for the temperature of the leaked low temperature gas is effective. Can be implemented. Further, the degree of freedom in setting the back pressure is increased, and suitable control can be realized.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of one or both of the structure and function may be substantially changed without departing from the spirit of the invention.

  The present invention is useful for an expansion turbine including a static pressure gas bearing.

1, 1A, 1B, 1C Expansion turbine device 10 Turbine body 11 Turbine impeller 12 Brake impeller 13 Rotating shaft 14 Hydrostatic gas bearing 14a Second radial hydrostatic bearing (braking gas chamber side)
14b Second thrust hydrostatic bearing (brake gas chamber side)
14c 1st thrust hydrostatic bearing (expansion chamber side)
14d First radial hydrostatic bearing (expansion chamber side)
15 Braking line 16 Turbine line 17 Bearing supply line 18 Exhaust line (mixed gas discharge path)
18a Bearing exhaust line (exhaust passage exclusively for bearing gas)
20 Braking gas chamber 21 Expansion chamber 22 Shaft insertion hole 23 Bearing chamber 24 Expansion chamber inlet 26 Expansion chamber outlet 27 Braking gas chamber inlet 29 Braking gas chamber outlet 30 First labyrinth seal (expansion chamber side)
31 Second labyrinth seal (braking gas chamber side)
32 3rd labyrinth seal 60 Temperature sensor 80 1st back pressure regulation valve 90 Control device 100 Pressure sensor 110 2nd back pressure regulation valve

Claims (4)

An expansion chamber, a braking gas chamber, and a shaft insertion hole are formed therein, and the shaft insertion hole communicates with the expansion chamber and the braking gas chamber, and a main body is formed so that a rotation shaft can be inserted;
A turbine impeller that is housed in the expansion chamber and expands the refrigerant gas;
A brake impeller housed in the braking gas chamber and braked by the same type of braking gas as the refrigerant gas;
The rotary shaft, which is inserted with a gap in the shaft insertion hole, the turbine impeller is provided at one end, and the brake impeller is provided at the other end,
A static pressure gas that is provided in a bearing chamber formed in the shaft insertion hole and rotatably supports the rotating shaft by a static pressure of the same type of bearing gas as the refrigerant gas supplied from the inlet and discharged from the outlet. A bearing,
A first labyrinth seal provided at a portion between the end of the bearing chamber on the expansion chamber side and a portion provided with the static pressure gas bearing;
A mixed gas discharge path for discharging a mixed gas of the bearing gas and a refrigerant gas leaking from the expansion chamber to the bearing chamber through the first labyrinth seal;
A first back pressure adjusting valve provided in the mixed gas discharge path for adjusting a back pressure of the static pressure gas bearing;
A temperature sensor provided in the mixed gas discharge path for measuring the temperature of the mixed gas;
A control device for controlling the first back pressure regulating valve so as to increase the back pressure of the static pressure gas bearing when the temperature of the mixed gas flowing through the mixed gas discharge path decreases;
An expansion turbine device comprising: The hydrostatic gas bearing includes first and second radial hydrostatic bearings that rotatably support the rotating shaft in a radial direction, and a thrust hydrostatic bearing that supports the rotating shaft so as to be rotatable in an axial direction. ,
In the bearing chamber, the first radial hydrostatic bearing, the thrust hydrostatic bearing, and the second radial hydrostatic bearing are provided in order from the expansion chamber toward the braking gas chamber, and The first labyrinth seal is provided at a portion between the end of the bearing chamber on the expansion chamber side and a portion where the first radial hydrostatic bearing is provided,
An upstream end of the mixed gas discharge path is connected to an outlet of the first radial hydrostatic bearing;
The expansion turbine apparatus according to claim 1, wherein an upstream end of a bearing gas exclusive discharge path is connected to an outlet of the thrust hydrostatic bearing and an outlet of the second radial hydrostatic bearing. The hydrostatic gas bearing includes first and second radial hydrostatic bearings that rotatably support the rotating shaft in a radial direction, and a thrust hydrostatic bearing that supports the rotating shaft so as to be rotatable in an axial direction. ,
In the bearing chamber, the first radial hydrostatic bearing, the thrust hydrostatic bearing, and the second radial hydrostatic bearing are provided in order from the expansion chamber toward the braking gas chamber, and A second labyrinth seal provided in a portion of the bearing chamber between the first radial hydrostatic bearing and the thrust hydrostatic bearing;
A bearing gas exclusive discharge path having an upstream end connected to an outlet of the thrust hydrostatic bearing and an outlet of the second radial hydrostatic bearing;
A second back pressure regulating valve that is provided in the bearing gas exclusive discharge path and that adjusts the back pressure of the thrust hydrostatic bearing and the second radial hydrostatic bearing;
A braking line having one end connected to the outlet of the braking gas chamber and the other end connected to the inlet of the braking gas chamber;
The expansion turbine apparatus according to claim 1, further comprising: a ventilation path having one end connected to the braking line and the other end connected to the bearing gas dedicated discharge path. The hydrostatic gas bearing includes first and second radial hydrostatic bearings that rotatably support the rotating shaft in a radial direction, and a thrust hydrostatic bearing that supports the rotating shaft so as to be rotatable in an axial direction. ,
In the bearing chamber, the first radial hydrostatic bearing, the thrust hydrostatic bearing, and the second radial hydrostatic bearing are provided in order from the expansion chamber toward the braking gas chamber, and The first labyrinth seal is provided at a portion between the end of the bearing chamber on the expansion chamber side and a portion where the first radial hydrostatic bearing is provided,
An upstream end of the mixed gas discharge path is connected to an outlet of the first radial hydrostatic bearing on the expansion chamber side;
The upstream end of a bearing gas exclusive discharge path is connected to the outlet on the braking gas chamber side of the first radial hydrostatic bearing, the outlet of the thrust hydrostatic bearing, and the outlet of the second radial hydrostatic bearing. 2. The expansion turbine device according to 1.

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