JP2017008776A - Expansion turbine device - Google Patents

Abstract

An object of the present invention is to suppress seal leakage of low-temperature gas in an expansion turbine apparatus including a static pressure gas bearing. An expansion turbine device (1) supplies a rotary shaft (13), static pressure gas bearings (14a to 14d), a first labyrinth seal (30), and a gas of the same type as a refrigerant in the middle of the first labyrinth seal (30). The upstream end is connected to the gas supply path 55 and the outlet of the bearing chamber 23 of the static pressure gas bearing, and the refrigerant gas that leaks from the expansion chamber 21 to the bearing chamber 23 through the first labyrinth seal 30 and the bearing gas that has passed through the static pressure gas bearing. And a bearing exhaust line (mixed gas discharge path) 18 for discharging a mixed gas of the first labyrinth seal 30 and a gas supplied in the middle of the first labyrinth seal 30, and the pressure of the gas supplied in the middle of the first labyrinth seal 30 is It is lower than the inlet pressure of the expansion chamber 21 and higher than the back pressure of the static pressure bearing. [Selection] 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, a shaft inserted through the shaft insertion hole with a gap, the rotating shaft provided with the turbine impeller at one end and the brake impeller at the other end, and the shaft insertion hole A hydrostatic gas bearing which is provided in a bearing chamber formed in the bearing chamber and rotatably supports the rotating shaft by a static pressure of a bearing gas of the same type as the refrigerant gas supplied from the inlet and discharged from the outlet; and the bearing And a labyrinth seal provided between the expansion chamber, a gas supply path for supplying the same kind of gas as the refrigerant gas in the middle of the labyrinth seal, and upstream of the bearing chamber outlet of the hydrostatic gas bearing The mixed gas of the bearing gas that is connected to the end and passed through the hydrostatic gas bearing, the refrigerant gas that leaks from the expansion chamber to the bearing chamber through the labyrinth seal, and the gas that is supplied in the middle of the labyrinth seal is discharged. And a mixed gas discharge path, wherein the pressure of the gas supplied in the middle of the labyrinth seal is lower than the inlet pressure of the expansion chamber and higher than the back pressure of the static pressure bearing.

  According to the above configuration, gas having a pressure lower than the inlet pressure of the expansion chamber and higher than the back pressure of the static pressure bearing is supplied in the middle of the labyrinth seal, and therefore leaks from the expansion chamber to the mixed gas discharge path via the labyrinth seal. The amount of the refrigerant gas to be determined is substantially determined by the gas supply pressure. Therefore, the leakage amount of the refrigerant gas with respect to the back pressure of the same static pressure gas bearing can be reduced as compared with the case where no gas is supplied. For example, when no gas is supplied, there is a method of increasing the bearing back pressure and reducing the labyrinth differential pressure in order to reduce the leakage amount of the refrigerant gas. On the other hand, since gas is supplied by the said structure, the leakage amount of the refrigerant gas from a labyrinth seal can be suppressed, without raising a bearing back pressure.

  The expansion turbine apparatus includes a first pressure sensor that measures the pressure of the gas, a pressure adjustment valve that is provided in the gas supply path, and that adjusts the pressure of the gas, and a second pressure that measures the inlet pressure of the expansion chamber. The apparatus may further include a pressure sensor and a control device that controls the pressure adjusting valve so that the pressure of the gas is lower than an inlet pressure of the expansion chamber and higher than a back pressure of the static pressure bearing.

  According to the above configuration, since the control device controls the gas pressure to be lower than the inlet pressure of the expansion chamber and higher than the back pressure of the static pressure bearing, there is no need to increase the bearing back pressure to reduce the amount of leakage. Further, it is possible to prevent a decrease in bearing performance due to an increase in back pressure.

  The control device controls the initial pressure of the gas supplied in the middle of the labyrinth seal to the same degree as the bearing back pressure, and the pressure of the gas when the temperature of the mixed gas flowing through the mixed gas discharge path decreases. The pressure regulating valve may be controlled to raise the pressure.

  According to the above configuration, when the refrigerant gas leaking from the expansion chamber through the labyrinth seal increases, the temperature of the mixed gas discharge path decreases, but by increasing the pressure of the gas supplied to the labyrinth seal, the turbine side pressure of the labyrinth seal And gas pressure can be balanced, and theoretically, leakage of low temperature gas from the turbine can be eliminated. Moreover, since the amount of leakage of the low temperature gas flowing on the turbine side is reduced, it is possible to prevent a temperature drop on the normal temperature side.

  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.

  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, a turbine nozzle 25, and an expansion chamber outlet 26 are formed in the lower part of the main body 10. The expansion chamber inlet 24 opens to the lower part of the main body 10. The turbine nozzle 25 communicates with the expansion chamber inlet 24 at one end and communicates with the expansion chamber 21 at the other end. The expansion chamber outlet 26 opens at the center lower portion of the main body 10, whereby the expansion chamber 21 of the turbine impeller 11 communicates with the outside of the main body 10. The refrigerant flowing into the expansion chamber inlet 24 is injected from the other end of the turbine nozzle 25 toward the turbine impeller 11. The refrigerant 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 gas bearings 14a and 14d that support the rotary shaft 13 rotatably in the radial direction, and thrust static pressure gas bearings 14b and 14c that support the rotary shaft 13 rotatably in the axial direction. Is provided. 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 second radial hydrostatic bearing 14a are sequentially provided in the bearing chamber 23 from the expansion chamber 21 toward the braking gas chamber 20. It is provided so that it may be located. 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 gap of the first radial hydrostatic bearing 14d flows. The refrigerant gas leaking from the expansion chamber 21 to the bearing chamber 23 of the first radial hydrostatic bearing 14 d flows into the fourth exhaust passage 42 through the first labyrinth seal 30.

  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. Incidentally, 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 bearing that flows upward from the other end (bearing outlet) of the first thrust hydrostatic bearing 14c. Gas (dotted 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. High-pressure 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. In this embodiment, normal temperature hydrogen gas of the same type as the refrigerant gas is used as the bearing gas. By supplying high-pressure bearing gas to the bearing gaps of the hydrostatic bearings 14a to 14d, the rotating shaft 13 can be supported rotatably in the main body 10, and the radial load and thrust load of the rotating shaft 13 can be improved. Can be supported. 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 hydrostatic bearings 14a to 14d. For this reason, the lifetime of the expansion turbine device 1 and the radial hydrostatic bearings 14a and 14d can be extended.

  A first labyrinth seal 30 is provided between the bearing chamber 23 and the expansion chamber 21 (see FIG. 1). A second labyrinth seal 31 is provided at a portion between the end of the bearing chamber 23 on the brake gas chamber 20 side and a portion where the brake-side radial hydrostatic bearing 14a is provided (see FIG. 1). The first labyrinth seal 30 and the second labyrinth seal 31 are provided so as to surround the outer peripheral side of the rotating shaft 13. In the present embodiment, a gas supply path 55 is provided in the middle of the first labyrinth seal 30 for supplying a normal temperature gas of the same type as the bearing gas.

  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 seal teeth are formed on the inner peripheral surface. These seal teeth are formed along the outer periphery of the rotating shaft 13. In the present embodiment, the seal teeth are formed on the stationary side (first labyrinth seal 30), but may be formed on the rotating shaft 13 side. Hereinafter, the seal tooth and the tooth gap are collectively referred to as one stage. Ideally, all the refrigerant flowing in from the expansion chamber inlet 24 flows out to the expansion chamber outlet 26 after passing through the turbine nozzle 25, but partially leaks to the first labyrinth seal 30 located on the rear surface of the turbine impeller 11. (See FIG. 1). The pressure of the leaked refrigerant gas gradually decreases every time it passes through each stage of the first labyrinth seal 30. In the present embodiment, one end of the gas supply path 55 penetrates the inside from the outer peripheral surface of the first labyrinth seal 30 and opens on the surface of the inner peripheral surface of the seal. In FIG. 4, one end of the gas supply path 55 is configured to supply gas from the inside of the first labyrinth seal 30 to the rotary shaft 13 from both the left and right sides of FIG. 4, but in the middle of the first labyrinth seal 30. As long as it is the structure which supplies the normal temperature gas of the same kind as refrigerant gas, it will not be limited to the structure of FIG.1 and FIG.4.

  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 device 1 includes a main body 10, a braking line 15, a turbine line 16, a bearing supply line 17, a bearing exhaust line 18, a gas supply path 55, and a first pressure sensor 60. A second pressure sensor 70, a third pressure sensor 80, a pressure regulating valve 90, a control device 100, and a temperature sensor 110.

  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 is lowered and lowered in pressure and maintained at room temperature by passing through the heat exchanger 53. .

  The turbine line 16 is a pipe for supplying a refrigerant 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 high-pressure 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 for sending a liquefied 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 bearing exhaust line 18 has an upstream end connected to the outlet of the bearing chamber 23 of the static pressure gas bearings 14 a to 14 d, and the turbine line 16 (expansion chamber) through the bearing gas that has passed through the static pressure gas bearings 14 a to 14 d and the first labyrinth seal 30. ) Is a mixed gas discharge path configured to discharge a mixed gas of the refrigerant gas leaking into the bearing chamber 23 and the gas supplied in the middle of the first labyrinth seal 30. In the present embodiment, the bearing 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. (See FIG. 1).

  The gas supply path 55 is a pipe for supplying the same type of gas as the refrigerant to the first labyrinth seal 30. One end of the gas supply path 55 is branched from the bearing supply line 17, and the other end of the gas supply path 55 penetrates the inside from the outer peripheral surface of the first labyrinth seal 30 and opens to the surface of the inner peripheral surface of the seal (FIG. 1). reference).

The first pressure sensor 60 is provided in the gas supply path 55 is configured to measure the pressure P ₁ of the gas. The first pressure sensor 60 is configured to output the measured pressure information to the control device 100.

The second pressure sensor 70 configured to measure the turbine line 16, the inlet pressure _{P 2} of the expansion chamber 21. The second pressure sensor 70 is configured to output the measured pressure information to the control device 100.

The third pressure sensor 80 is provided in the bearing exhaust line 18 and is configured to measure the bearing back pressure P ₃ of the bearing exhaust line 18. The third pressure sensor 80 is configured to output the measured pressure information to the control device 100.

The pressure regulating valve 90 is provided in the gas supply path 55 configured to adjust the pressure P ₁ of the gas. The pressure adjustment valve 90 is configured to adjust the opening of the valve based on a command from the control device 100.

The temperature sensor 110 is provided in the bearing exhaust line 18 and is configured to measure the bearing exhaust temperature T ₁ of the bearing exhaust line 18. The temperature sensor 110 is configured to output the measured temperature information to the control device 100.

The control device 100 controls the pressure regulating valve 90 based on the gas pressure P ₁ , the inlet pressure P ₂ of the expansion chamber 21, the back pressure P ₃ of the static pressure gas bearings 14 a to 14 d, and the bearing exhaust temperature T _1. Configured. In the present embodiment, the control device 100 has a function of controlling not only the expansion turbine device 1 but also other devices such as a compressor. The control device 100 is, for example, a microcomputer mainly composed of a CPU, a ROM, and an input / output interface. On the input side of the control device 100, process data such as a gas pressure P ₁ , an inlet pressure P ₂ of the expansion chamber 21, a back pressure P ₃ of the bearing exhaust line 18, a measured value of the bearing exhaust temperature T ₁ , and a turbine speed are stored. Entered. A pressure regulating valve 90, a supply valve, a discharge valve, and the like are connected to the output side of the control device 100. The CPU executes a control program stored in the ROM. Further, the CPU controls the pressure regulating valve 90 so as to obtain the gas pressure P ₁ , the inlet pressure P ₂ of the expansion chamber 21, and the bearing back pressure P ₃ as set while monitoring the temperature measurement value of the process data. . Controller 100, the initial pressure of the gas pressure P ₁ set at the same level as the bearing back pressure P _3, when the bearing exhaust temperatures T ₁ is lower than the reference value T _S, raising the pressure P ₁ of the gas Thus, the pressure regulating valve 90 is controlled. Here reference temperature T _S is the value of a predetermined value or a predetermined range in a normal.

During operation of the expansion turbine device 1, high-pressure 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. The bearing gas of the static pressure gas bearings 14a to 14d is discharged from the bearing exhaust line 18. The pressure P ₂ of the expansion chamber inlet 24 reduces the pressure in the turbine nozzle 25, the main stream of refrigerant turbine line 16 (expansion chamber) adiabatic expansion in the turbine impeller 11 towards the expansion chamber outlet 26. A first labyrinth seal 30 is provided at a portion between the end on the expansion chamber 21 side where the turbine impeller 11 is accommodated and a portion where the radial hydrostatic bearing 14 d is provided. There is refrigerant gas leaking from the line 16 (expansion chamber) to the bearing. For this reason, the bearing exhaust line 18 contains a mixed gas of the bearing gas and the leaked refrigerant gas. At this time, the amount of leakage of the first labyrinth seal 30 depends on the differential pressure between the pressure P _{4 at} the inlet of the first labyrinth seal 30 and the pressure at the outlet of the first labyrinth seal 30. Inlet or outlet of the first labyrinth seal 30 is the installation difficult accurate pressure measurement of the sensor is difficult, the pressure of the first labyrinth seal 30 outlet is substantially equal to approximately the bearing back pressure P _3.

In the present embodiment, a gas having a pressure P ₁ lower than the inlet pressure P ₂ of the expansion chamber 21 and higher than the back pressure P ₃ of the static pressure bearing is supplied in the middle of the first labyrinth seal 30. In other words, the amount of refrigerant gas leaks from the expansion chamber 21 via a first labyrinth seal 30 into the bearing exhaust line 18 is substantially determined by the supply pressure P ₁ of the gas. Therefore, the leakage amount of the refrigerant gas with respect to the back pressure of the same static pressure gas bearing can be reduced as compared with the case where no gas is supplied. For example, when no gas is supplied, there is a method of increasing the bearing back pressure and reducing the labyrinth differential pressure in order to reduce the leakage amount of the refrigerant gas. On the other hand, when supplying gas like this embodiment, the leakage amount of the refrigerant gas from the 1st labyrinth seal 30 can be suppressed, without raising a bearing back pressure.

Here, since the labyrinth seal inlet pressure is actually lower than the expansion chamber inlet, even if the gas pressure is lower than the expansion chamber inlet pressure, if a gas higher than the labyrinth seal inlet pressure is supplied, the labyrinth seal inlet pressure flows back into the expansion chamber. Room temperature gas will flow. Therefore, it is desirable that the gas supply pressure P ₁ be lower than the inlet pressure P ₄ of the first labyrinth seal 30. Inlet pressure P ₄ of the first labyrinth seal 30 is substantially equal to the outlet pressure of the turbine nozzle 25 FIG. Thereby, room temperature gas can be prevented from flowing into the expansion chamber 21 from the inlet of the first labyrinth seal 30.

Further, when the refrigerant gas leaking from the turbine line 16 (expansion chamber) to the bearing through the first labyrinth seal 30 increases, the temperature of the bearing exhaust line 18 measured by the temperature sensor 110 decreases. The control device 100 controls the pressure regulating valve 90 so as to increase the pressure P ₁ of the gas supplied to the first labyrinth seal 30 when the bearing exhaust temperature T ₁ is lower than the reference value T _S. Accordingly, the pressure P ₁ on the turbine side of the inlet pressure and the gas in the first labyrinth seal 30 can be balanced, theoretically it is possible to eliminate the leakage of cold gas from the turbine. As a result, it is possible to prevent a decrease in turbine performance and a temperature decrease on the normal temperature side.

(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 block diagram showing a configuration of an expansion turbine apparatus 1A according to the second embodiment. As shown in FIG. 6, the expansion turbine device 1 </ b> A includes a back pressure adjusting valve 120 that is provided in the bearing exhaust line 18 and adjusts the back pressure P ₃ of the static pressure gas bearings 14 a to 14 d as compared with the first embodiment. further comprising, control device 100, the point of controlling the back pressure regulating valve 120 to raise the back pressure P ₃ of the externally pressurized gas bearing 14a~14d when the temperature of the mixed gas flowing in the bearing exhaust line 18 is lowered Is different. According to the above configuration, it is possible by increasing the back pressure P ₃ of the hydrostatic bearing, as compared with the first embodiment, enhance the effect of leakage of cryogenic gas from the turbine.

Although the present embodiment has been controlled to increase only the back pressure P ₃ of the externally pressurized gas bearing 14a to 14d, to prevent the differential pressure of the inlet / outlet of the bearing is lowered, the expansion turbine apparatus 1A bearings A means (not shown) for controlling the pressure of the supply line 17 may be further provided.

  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 hydrostatic bearing.

DESCRIPTION OF SYMBOLS 1,1A Expansion turbine apparatus 10 Turbine main body 11 Turbine impeller 12 Brake impeller 13 Rotating shaft 14 Static pressure gas bearing 14a 2nd radial static pressure bearing (brake 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 Bearing exhaust line (mixed gas discharge path)
20 Braking gas chamber 21 Expansion chamber 22 Shaft insertion hole 23 Bearing chamber 24 Expansion chamber inlet 25 Turbine nozzle 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)
60 first pressure sensor 70 second pressure sensor 80 third pressure sensor 90 pressure regulating valve 100 control device 110 temperature sensor 120 back pressure regulating valve

Claims (3)

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 labyrinth seal provided between the bearing chamber and the expansion chamber;
A gas supply path for supplying the same type of gas as the refrigerant gas in the middle of the labyrinth seal;
An upstream end is connected to the bearing chamber outlet of the static pressure gas bearing, and the bearing gas that has passed through the static pressure gas bearing and the refrigerant gas that leaks from the expansion chamber to the bearing chamber through the labyrinth seal and the middle of the labyrinth seal A mixed gas discharge path for discharging a mixed gas with the gas supplied to
With
An expansion turbine apparatus, wherein a pressure of gas supplied in the middle of the labyrinth seal is lower than an inlet pressure of the expansion chamber and higher than a back pressure of the static pressure bearing. A first pressure sensor for measuring the pressure of the gas;
A pressure adjusting valve provided in the gas supply path for adjusting the pressure of the gas;
A second pressure sensor for measuring an inlet pressure of the expansion chamber;
The expansion turbine apparatus according to claim 1, further comprising a control device that controls the pressure regulating valve so that the pressure of the gas is lower than an inlet pressure of the expansion chamber and higher than a back pressure of the static pressure bearing. .   The control device controls the initial pressure of the gas supplied in the middle of the labyrinth seal to the same degree as the bearing back pressure, and the pressure of the gas when the temperature of the mixed gas flowing through the mixed gas discharge path decreases. The expansion turbine apparatus according to claim 2, wherein the pressure regulating valve is controlled to raise the pressure.

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