JP6049565B2 - Geothermal turbine - Google Patents

Description

  The present invention relates to a geothermal turbine, and in particular, circulates a cooling medium between a first-stage stationary blade on the steam introduction side and a rear-stage stationary blade in the geothermal turbine, and the first-stage stationary blade is cooled by heat exchange. The present invention relates to a geothermal turbine that heats a rear stator blade to prevent scale adhesion to the first stator blade and prevent erosion of the rear stator blade.

In recent years, as geothermal energy utilization, for example, there is a geothermal power generation system 1 shown in FIG. 10, and the geothermal power generation system 1 leads a production well 2 that generates hot water by a heat source in a deep underground, and leads from the production well 2 to the ground. A separator 3 that separates boiling hot water from steam is provided.
The geothermal power generation system 1 includes a reduction well 4 that returns hot water separated by the separator 3, a geothermal turbine 5 that is rotated by the separated steam, and a generator 6 that is connected to the geothermal turbine 5.
The geothermal power generation system 1 further includes a condenser 7 that warms the steam that has passed through the geothermal turbine 5 and a cooling tower 8 that cools the hot water.

FIG. 11 shows an example of a steam turbine as the geothermal turbine 5 used in the geothermal power generation system 1.
The steam turbine 5 is, for example, a well-known axial-flow steam turbine, and the rotor blades 5b on the rotor shaft 5a side and the stationary blades (nozzles) 5d fixed on the casing 5c side alternately oppose each other in multiple stages. Are lined up like this. The rotor of the generator 6 is connected to the rotor shaft 5a. The steam from the separator 3 is introduced from the steam inlet through the first stage stationary blade 5d, passes through the multistage moving blade 5b and the stationary blade 5d while expanding, is discharged from the steam discharge port, and the moving blade 5b is rotated by kinetic energy. Then, the rotor shaft 5a is rotated, the rotor of the generator 6 is rotationally driven, and electric power is taken out.

  By the way, high-temperature hot water ejected from the production well contains more calcium and dissolved silica than well water and river water, and therefore, scales such as calcium carbonate and amorphous silica are easily deposited. Particularly in the above-ground part and the reduction well, it is a problem to suppress the silica scale generated by the temperature drop of the hot water in the above-ground part.

Up to now, as a means for removing the scale deposited on the nozzle (especially the first stage stationary blade) of the steam turbine for geothermal power generation, there is one disclosed in Patent Document 1, for example.
Here, it has a cooling water passage penetrating the inside of the profile of the nozzle plate arranged at a predetermined angle as many as necessary in an annular shape, and a plurality of nozzle plates are arranged so that the whole constitutes several blocks. In the block, the cooling water passages are connected and communicated with each other through a cooling water connecting pipe, and the cooling water is supplied from the cooling water supply pipe and returned to the water drain pipe in the cold part.

Further, in the steam turbine 5 described above, as the steam flows while expanding from the first stage stationary blade to the rear stage stationary blade near the steam discharge port, it passes as wet steam. The water droplets cause erosion and damage the stationary blade.
In order to avoid such damage due to erosion, the present applicant, for example, disclosed in Patent Document 2, the wet steam is applied to the final stage moving blade of the turbine stage composed of the moving blade and the stationary blade. In order to prevent corrosion due to collision, dry steam is introduced from the thirst steam inlet pipe into the annular pocket of the blade ring of the final stage stationary blade.

Japanese Patent No. 3046907 JP 2012-140901 A

However, none has been developed which has a cooling function for the first stage stationary blade and a function for preventing the corrosion phenomenon of the last stage stationary blade in the steam turbine.
The present invention has been proposed from the above background. The first stage stationary blade in the geothermal turbine is cooled by a heat exchange action with the cooling medium, and the cooling medium used for cooling the first stage stationary blade is further cooled. An object of the present invention is to provide a geothermal turbine that is used for heating a blade and prevents the adhesion of scale to the first stage stationary blade and the erosion of the stationary blade on the rear stage side.

  In order to solve the above-mentioned problem, in the present invention according to claim 1, a plurality of moving blade rows arranged on the outer periphery of the rotor shaft and an inner periphery of a casing for housing the rotor shaft are respectively supported via blade attachment portions. A geothermal turbine comprising a plurality of stationary blade rows, wherein the moving blade rows and the stationary blade rows are alternately arranged opposite to each other, wherein the first stage stationary blade row of the plurality of stationary blade rows is a cooling medium. A cooling section that cools by heat exchange, a heating section that heats the stationary blade row downstream of the first stage stationary blade by heat exchange with the cooling medium, and a cooling medium in which the cooling medium circulates between the cooling section and the heating section A medium circulation unit.

Thereby, in the first stage stationary blade, the first stage stationary blade is cooled by heat exchange with the cooling medium, and then, the cooling medium whose temperature has increased due to heat exchange with the cooling medium is exchanged with the rear stage stationary blade by the heat exchange with the second stage stationary blade. The side vane is heated.
As a result, the high temperature heat at the turbine inlet is not easily transmitted to the stationary blade in the first stage stationary blade, and scale adhesion is suppressed, and the downstream stationary blade is heated and water droplets attached to the surface of the stationary blade are evaporated by wet steam. As a result, the generation of erosion in the rotor blade on the rear stage side is suppressed.

  Further, the present invention according to claim 2 is characterized in that the cooling section for cooling the first stage stationary blade row includes a cooling medium flow path through which a cooling medium flows in each stationary blade in the first stage stationary blade row.

  As a result, the cooling medium flows through the cooling medium flow path in each stationary blade in the first stage stationary blade row, so that the cooling medium is in direct contact with the stationary blade and makes it difficult for high temperature heat at the turbine inlet to be transmitted to the stationary blade. Can do.

  In the present invention according to claim 3, the cooling section for cooling the first stage stationary blade row is composed of a cooling medium flow path provided inside the blade mounting portion that supports the first stage stationary blade row. .

  As a result, the stationary blade is indirectly cooled by heat exchange by flowing the cooling medium through the cooling medium flow path provided in the blade attachment portion that supports the first stage stationary blade row.

  In the present invention described in claim 4, the heating unit for heating the stationary blade row on the rear stage side includes a cooling medium flow path through which a cooling medium flows in each stationary blade in the stationary blade row. .

  As a result, the cooling blade is heated by the heat exchange action between the cooling medium and the stationary blade through the cooling medium passage by flowing the cooling medium through the cooling medium passage in the latter stator blade, and the latter side It is possible to evaporate water droplets due to the wet steam generated on the surface of the stationary blades, and to prevent erosion from occurring on the rotor blades on the rear stage side.

  Further, in the present invention according to claim 5, the decompression expansion unit is interposed in the cooling medium forward path from the cooling unit to the heating unit in the cooling medium circulation unit, and the cooling medium from the cooling unit is decompressed to reduce the cooling medium after depressurization. The vapor phase component is supplied to the heating unit to be condensed, and the liquid phase component of the chilled heat medium after decompression is joined to the cooling medium return path from the heating unit to the cooling unit.

Thereby, after cooling the first stage stationary blade by heat exchange in the first stage stationary blade, the cooling medium is decompressed and expanded in the decompression and expansion section. Then, a part of the cooling medium evaporates to form a gas phase, while a part is returned to the cooling medium return path from the heating unit to the cooling unit in a liquid phase state.
The cold medium in the gas phase state sent to the heating unit is condensed and returned to the liquid phase. The heating unit can increase the amount of heat exchange by condensing the cooling medium, and can heat the rear stator blade.

According to the present invention, even if the first stage stationary blade is cooled by heat exchange in the first stage stationary blade, even if the heat energy of the cooling medium is lost and the temperature is increased, the stationary blade is removed by heat exchange with the rear stage stationary blade. By heating, the temperature of the cooling medium is lowered again, and this cooling medium can be used for cooling the first stage stationary blade by heat exchange with the first stage stationary blade.
Thus, since the energy lost by stationary blade cooling can be reduced by stationary blade heating, a decrease in cooling effect can be suppressed as compared with a method in which only stationary blade cooling is performed.
In addition, when only the stator blades are heated, the steam is inevitably reduced due to the condensation of the gas phase, but by using a cooling medium circulation system between the first stage stator blades and the rear stage stator blades, heat loss is reduced because there is less heat loss. There is no need to introduce it, and it is highly efficient.

It is a whole system explanatory view showing an example of a geothermal power generation system. It is principal part sectional explanatory drawing which shows an example of the geothermal turbine used for the geothermal power generation system shown in FIG. The first embodiment of the cooling unit of the first stage stationary blade and the heating unit of the rear stage stationary blade, and the cooling medium that circulates the cooling medium between the cooling unit and the heating unit, which is provided in the geothermal turbine shown in FIG. It is the systematic diagram of a circulation part, and the enlarged view of a first stage stationary blade and a moving blade. It is a typical cutting arrow line view which shows an example of the blade | wing attachment part which supports the first stage stationary blade and the first stage stationary blade cut | disconnected along the AA line shown in FIG. FIG. 4 is a schematic system diagram of a cooling unit of a first stage stationary blade and a heating unit of a rear stage stationary blade, and a cooling medium circulation unit that circulates a cooling medium between the cooling unit and the heating unit, showing a second embodiment. . FIG. 5 is a schematic system diagram of a cooling unit for a first stage stationary blade and a heating unit for a rear stage stationary blade, and a cooling medium circulation unit that circulates a cooling medium between the cooling unit and the heating unit, showing a third embodiment. . FIG. 10 is a schematic system diagram of a cooling unit of a first stage stationary blade and a heating unit of a rear stage stationary blade, and a cooling medium circulation unit that circulates a cooling medium between the cooling unit and the heating unit, showing a fourth embodiment. . FIG. 10 is a schematic system diagram of a cooling unit of a first stage stationary blade and a heating unit of a rear stage stationary blade, and a cooling medium circulation unit that circulates a cooling medium between the cooling unit and the heating unit, showing a fifth embodiment. . FIG. 10 is a schematic system diagram of a cooling unit for a first stage stationary blade and a heating unit for a rear stage stationary blade, and a cooling medium circulation unit that circulates a cooling medium between the cooling unit and the heating unit, showing a sixth embodiment. . It is a schematic system explanatory drawing which shows an example of the conventional geothermal power generation system. It is principal part sectional drawing which showed an example of the geothermal turbine used for the geothermal power generation system shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative positions, and the like of the components described in the following embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely descriptions. It is just an example.

FIG. 1 shows an embodiment of a geothermal power generation system 10 in which a geothermal turbine according to the present invention is used, and a description will be given based on the attached drawings.
This geothermal power generation system 10 includes a production well 11 that generates high-temperature and high-pressure hot water from a deep heat source, a separator 12 that separates the hot water boiled by guiding the high-temperature and high-pressure hot water to the ground, a separator, The reduction well 13 that returns the hot water separated in 12, the geothermal turbine 14 that is operated by the separated steam, the generator 15 that is connected to the geothermal turbine 14, and the recovery that warms the steam that has passed through the geothermal turbine 14. The water device 16 and the cooling tower 17 which cools warm water are provided.

  Hot water is taken out from the production well 11 to the separator 12 through the hot water outlet passage 18. A flow rate adjusting valve 19 is interposed in the hot water outlet channel 18.

The separator 12 is, for example, a cyclone type steam / water separator, and steam is separated from hot water by collecting steam on the upper side of the separator container and hot water on the lower side of the container. The steam separated by the separator 12 is sent to the geothermal turbine 14 through the steam flow path 20.
The hot water collected on the container lower side of the separator 12 is returned to the reduction well 13 through the reflux path 21.

  Although the details of the geothermal turbine 14 will be described later, for example, a well-known axial flow steam turbine 14 can be used.

  The condenser 16 condenses the steam that has passed through the geothermal turbine 14 and warms it up. Here, the condenser 16 uses water cooled by the cooling tower 17 to condense the steam. Yes.

Hot water from the condenser 16 is introduced into the cooling tower 17 by a pump 23 interposed through the condensate flow path 22.
The cooling tower 17 cools the hot water from the condenser 16 by bringing it into contact with the outside air that is forcibly sent by the blower 24 in the cooling tower 17. At this time, part of the condensate is evaporated, so that the warm water is further effectively cooled by the latent heat of vaporization.

Next, the main part of the geothermal turbine 14 will be described with reference to FIG.
The geothermal turbine 14 is arranged in a row such that the moving blades 26 projecting on the rotor shaft 25 side and the stationary blades 28 fixed on the casing 27 side via the blade mounting portions 27b alternately face each other in multiple stages. It is assumed to be configured. The moving blades 26 are arranged in a plurality of rows in the circumferential direction of the rotor shaft 25 to form a moving blade row, and the stationary blades 28 are arranged in a plurality of rows in the circumferential direction on the inner peripheral side of the casing 27 via the blade mounting portions 27b. It is installed and constitutes a stationary blade row. In FIG. 2, the moving blade 26 and the stationary blade 28 are shown as a part of the moving blade row and the stationary blade example, respectively. Therefore, hereinafter, examples of the moving blade row and the stationary blade will be described as the moving blade 26 and the stationary blade 28, respectively.
In the geothermal turbine 14, the steam is introduced from the steam inlet 29 through the first stage stationary blade 28 a near the steam inlet 29 among the stationary blades 28, passes between the multistage moving blades 26 and the stationary blades 28, and is a steam discharge port. It is configured to be released from (not shown).

(First embodiment)
As shown in FIG. 3, the geothermal turbine 14 as described above circulates a cooling medium between the first stage stationary blades 28a and the stationary blades 28e on the rear side of the first stage stationary blades 28a (hereinafter, the rear stage stationary blades 28e). A cooling medium circulating unit 30 is provided.
That is, the geothermal turbine 14 includes a cooling unit 31 that cools the first stage stationary blade 28a by heat exchange with a cooling medium.
Further, a heating unit 32 is provided that heats the rear stage stationary blade 28e by heat exchange with the cooling medium rather than the first stage stationary blade 28a.
Further, the cooling medium circulation unit 30 includes a cooling medium forward path 30a through which a cooling medium flows from the cooling unit 31 in the first stage stationary blade 28a to the heating unit 32 in the rear stage stationary blade 28e, and the first stage stationary blade 28a from the heating unit 32 in the rear stage stationary blade 28e. And a cooling medium return path 30b for returning to the cooling unit 31 in the above. A cooling medium forcibly circulating the cooling medium is interposed in the cooling medium return path 30b.

The cooling section 31 that cools the first stage stationary blade 28a is provided with, for example, an annular cooling section 40 that continuously circulates as a cooling medium flow path provided inside the blade attachment section 27b that supports the first stage stationary blade 28a (see FIG. 2, see FIG. 3 and FIG.
Here, the blade attachment portion 27 b is composed of an annular outer ring 27 b that is fixed to the inner periphery of the casing 27 and is formed of a member different from the casing 27. An annular cooling unit 40 is provided inside the outer ring 27b.
An inner ring 27i is provided on the inner peripheral side of the first stage stationary blade row 28a supported by the outer ring 27b.
And the annular cooling part 40 is comprised as the outer ring | wheel annular cooling part 40p which carries out one turn around concentric with the outer ring | wheel 27b. In addition, the outer ring annular cooling unit 40p is configured to circulate cooling water with the cooling medium circulation unit 30 through an inlet 40pin and an outlet 40pout that are arranged close to each other at predetermined positions.

In the cooling unit 31 that cools the first-stage stationary blade 28a as described above, the first-stage stationary blade 28a that is heated when steam (for example, 200 ° C. or more) from the steam inlet 29 passes through the ring is cooled in the blade mounting portion 27b. Cooling is performed indirectly by heat exchange by flowing cooling water through the portion 40.
That is, in the first stage stationary blade 28a, the scale is generated by increasing the temperature by the high temperature heat at the turbine inlet and repeating the drying and wetting. Therefore, by cooling the first stage stationary blade 28a, the repeated drying and wetting of the first stage stationary blade 28a is prevented. The scale is prevented from being generated on the first stage stationary blade 28a.

Next, the heating unit 32 in the rear stage stationary blade 28e will be described.
The heating unit 32 in the rear stage stationary blade 28e is provided with a cooling medium flow path 34 in which the inside of the rear stage stationary blade 28e is perforated and the cooling medium flows. The cooling medium flow passage 34 is a pair of through passages 34d and 34u penetrating through the rear stationary blade 28e in the vertical direction in the drawing. The heat exchange property with the rear stationary blade 28e is directly enhanced by the cooling medium entering and exiting the rear stationary blade 28e in the vertical direction.

The geothermal turbine 14 according to the first embodiment is as described above. Next, the operation and action will be described.
In the geothermal power generation system 10 shown in FIG. 1, the steam from the separator 12 is introduced from the steam inlet 29 of the geothermal turbine 14 through the first stage stationary blade 28 a and passes between the multistage moving blade 26 and the stationary blade 28 while expanding. It is discharged from the steam discharge port, and the rotor blades 26 are rotated by the kinetic energy to rotate the rotor shaft 25, and the rotor of the generator 15 is rotationally driven to extract electric power.

When the steam from the separator 12 is introduced from the steam inlet of the geothermal turbine 14 through the first stage stationary blade 28a, the steam has a high temperature and high pressure of about 200 ° C.
The steam expands as it progresses between the first stage stationary blade 28a and the moving blade 26 and sequentially between the rear stationary blade 28 and the moving blade 26, and heat energy is converted into kinetic energy. When it reaches the rear stationary blade 28e, it becomes a low temperature steam of about 70 ° C. As the low temperature steam expands to a low pressure as a result of the expansion, the humidity rises (approximately 16%) and passes through the rear stage stationary blade 28e, resulting in condensation on the surface of the rear stage stationary blade 28e.

The cooling medium 31 in the first stage stationary blade 28a is sent to the cooling medium 31 through the cooling medium return path 30b of the cooling medium circulation section 30 under the action of the pump 33, and close to the steam inlet 29 of the geothermal turbine 14 having the highest temperature. It flows into the outer ring annular cooling part 40p of the outer ring 27b through the inlet 40pin arranged at the position.
In this case, since the outer ring annular cooling portion 40p is configured as a cooling water pipe 30p that circulates once in the circumferential direction of the outer ring 27b, the first-stage stationary blade 28a supported inside the outer ring 27b is indirect. The first stage vane 28a is cooled so that the high temperature heat at the steam inlet is not easily transmitted to the first stage vane 28a so that the heat exchange is performed uniformly between the two, and the first stage vane 28a does not dry. it can.

In the cooling section 31 of the first stage stationary blade 28a, heat exchange is performed, and the temperature of the cooling medium flowing out from the cooling section 31 is increased by the heat taken from the first stage stationary blade 28a, and the cooling medium circulation path 30a of the cooling medium circulation section 30 is heated. To the heating section 32 of the rear stationary blade 28e.
When a cooling medium is provided to the heating unit 32 of the rear stationary blade 28e, the cooling medium enters and exits in the vertical direction through the through passages 34d and 34u, so that heat exchange with the rear stationary blade 28e can be performed directly.
Here, water droplets are attached to the surface of the rear stationary vane 28e by low-temperature steam, but heat is directly received from the cold medium by heat exchange with the cold medium and heated. As a result, water droplets can be evaporated from the surface of the rear stationary blade 28e, and occurrence of moving blade erosion or the like due to moisture can be avoided.

As described above, according to the present embodiment, the first stage vane 28a is cooled by heat exchange in the first stage vane 28a, so that even if the heat energy of the cooling medium is lost and the temperature rises, By heating the stationary blade 28e by heat exchange with the stationary blade 28e, the temperature of the cooling medium decreases again, and this cooling medium can be used for cooling the first-stage stationary blade 28a by heat exchange with the first-stage stationary blade 28a. it can.
Thus, since the energy lost by stationary blade cooling can be reduced by stationary blade heating, a decrease in cooling effect can be suppressed as compared with a method in which only stationary blade cooling is performed.
Furthermore, in the case where only the stationary blade heating is performed, the steam is inevitably lowered due to the condensation of the gas phase. However, since the cooling medium circulation system of the first stage stationary blade 28a and the rear stage stationary blade 28e is used, the heat loss is reduced. It is not necessary to introduce steam, and high efficiency can be ensured.

(Second Embodiment)
The present invention can also be implemented by the following second embodiment.
In the second embodiment, as shown in FIG. 5, the cooling unit 31 in the first stage stationary blade 28a includes a cooling medium flow path 35 through which the cooling medium flows in the first stage stationary blade 28a, like the heating unit 32 of the rear stage stationary blade 28e. .
The cooling medium passage 35 is a pair of through passages 35d and 35u penetrating in the first stage stationary blade 28a in the vertical direction in the drawing. Heat exchange with the first stage stationary blade 28a is directly performed by the cooling medium flowing in and out of the first stage stationary blade 28a in the vertical direction.
In addition, the cooling medium circulating unit 30 is not substantially different from the first embodiment, and can provide the same effects.

  As a result, by flowing the cooling medium through the cooling medium flow path 35 in each stationary blade 28a in the first stage stationary blade 28a, the cooling medium directly contacts the stationary blade 28a, and the high temperature heat at the turbine inlet is transferred to the stationary blade 28a. It can be difficult to communicate.

(Third embodiment)
The present invention can also be implemented as shown in FIG.
In the geothermal turbine 14 in this case, the decompression expansion unit 50 (flasher 50) is interposed in the cooling medium forward path 30a of the cooling medium circulation unit 30 from the cooling unit 31 in the first stage stationary blade 28a to the heating unit 32 in the rear stage stationary blade 28e. ing.
Although the detailed structure of the flasher 50 is omitted, the cooling unit 31 of the first stage stationary blade 28a is subjected to heat exchange with the first stage stationary blade 28a, and the high-pressure cooling water whose temperature has risen is decompressed and expanded. It has a function to vaporize the water. Then, the vaporized cooling water is sent to the heating unit 32 in the rear stage stationary blade 28e, and heat exchange is directly performed between the rear-stage stationary blade 28e and the gas phase state cooling medium sent to the heating unit 32. Yes.

  The flasher 50 is connected to the cooling medium return path 30b so as to return the liquid phase component of the cooling medium after decompression to the cooling medium return path 30b from the heating section 32 to the cooling section 31.

According to the third embodiment as described above, the cooling medium is decompressed and expanded in the flasher 50 after the first stage vane 28a is cooled by heat exchange in the first stage vane 28a. Then, a part of the cooling medium evaporates to form a gas phase, while a part thereof is returned to the cooling medium return path 30b from the heating unit 32 to the cooling unit 31 in a liquid phase state.
The gas-phase state cooling medium sent to the heating unit 32 directly exchanges heat with the rear stage stationary blade 28e by entering and exiting the rear stage stationary blade 28e in the vertical direction through the through passages 34d and 34u of the rear stage stationary blade 28e. By condensing with the latent heat of vaporization, the heat of condensation can be released and the rear stationary blade 28e can be heated.
After the heat exchange in the heating unit 32, the cooling medium returns to the liquid phase and merges with the cooling medium in the liquid phase returned from the flasher 50 in the cooling medium return path 30 b, and is cooled by the cooling unit 31 in the first stage stationary blade 28 a by the pump 33. Then, it is again subjected to heat exchange with the first stage stationary blade 28a.

As described above, in the third embodiment, the cooling medium partially vaporized by the expansion under reduced pressure in the flasher 50 is subjected to heat exchange with the heating unit 32, so that the cooling medium is made use of latent heat of evaporation. By condensing, the amount of heat exchange can be increased, and the rear stage stationary blade 28e can be efficiently heated.
By configuring as described above, it is possible to adjust the pressure of the closed cycle corresponding to the first stage stationary blade 28a having a high turbine internal pressure, the rear stage stationary blade 28e having a decreased pressure, and the vicinity of the final stage. Risks such as leakage and suction can be reduced, and reliability is improved.

(Fourth embodiment)
The present invention can also be implemented as shown in FIG.
In the fourth embodiment, even if the flasher 50 in the third embodiment is omitted, in order to enable cooling and heating by heat exchange, the cooling medium flowing through the cooling medium circulation path 30a of the cooling medium circulation unit 30 is a gas-liquid. The cooling medium is selected so that it becomes a two-phase flow (saturated steam). The temperature and pressure of the cooling medium may be adjusted in accordance with the standard of the geothermal turbine 14 used and other various piping and specifications.
Moreover, in order to make a cooling-heat medium become a gas-liquid two-phase flow, it is realizable also by adjusting operation state (output). That is, at the design point (100% load operation), even if the cooling medium is a single phase, there is a possibility of a two-phase flow by setting the partial load operation (for example, output 50%).

  If the cooling medium is used in a gas-liquid two-phase flow, high-speed and uniform heating by latent heat heating can be expected. However, care must be taken because the heating efficiency will be reduced if not used in a dry state, and the temperature will drop if the pressure drops due to pressure loss such as piping resistance.

As mentioned above, about the geothermal turbine concerning this invention, 1st-4th embodiment was mentioned and the effect was demonstrated in detail, respectively.
The geothermal turbine according to the present invention is not limited to the first to fourth embodiments.
For example, as shown in FIG. 8, the cooling medium can be a gas phase, that is, a gas such as air. In this case, the fan F is interposed in the cooling medium return path 30 b of the cooling medium circulation unit 30. However, the use of gas for the cooling medium has a low heat exchange efficiency compared to other cooling cases.
Further, as shown in FIG. 9, a liquid such as water or a low boiling point medium can be considered as the cooling medium. Examples of the low boiling point medium include a mixture of isobutane, chlorofluorocarbon, or ammonia + water.
By using a low-boiling point medium, as long as the sealing structure of the cooling medium circulating unit 30 can be secured, the cooling medium boils and vaporizes even at a lower temperature than water, so that more efficient heat exchange can be expected. .

The present invention is applicable to geothermal turbines of various scales and of various systems.
Further, the geothermal turbine in the present invention can be applied to products whose turbine operating conditions change regardless of the turbine for geothermal power generation (for example, a turbocharger turbine, a turbine used in an underwater vehicle).

14 Geothermal turbine 23 Pump 25 Rotor shaft 26 Rotor blade 27 Casing 27b Blade attachment part (outer ring)
27i Inner ring 28 Stator blade 28a First stage stator blade 29 Steam inlet 30 Cooling medium circulating section 30a Cooling medium forward path 30b Cooling medium return path 31 Cooling section 32 Heating section 33 Pump 34, 35 Cooling medium flow paths 34d, 34u, 35d, 35u Through-path 40 Annular cooling part 40p Outer ring annular cooling part 40pin Inlet pipe 40pout Outlet pipe 50 Flasher F Fan

Claims (5)

A plurality of moving blade rows arranged on the outer periphery of the rotor shaft, and a plurality of stationary blade rows supported on the inner periphery of a casing that houses the rotor shaft via blade attachment portions, A geothermal turbine having stationary blade rows alternately arranged,
Among the plurality of stationary blade rows, a cooling unit that cools the first-stage stationary blade row by heat exchange with a cooling medium;
A heating unit that heats the stationary blade row on the rear stage side of the first stage stationary blade by heat exchange with the cooling medium;
A cooling medium circulating section in which a cooling medium circulates between the cooling section and the heating section;
A geothermal turbine characterized by comprising:   2. The geothermal turbine according to claim 1, wherein the cooling unit that cools the first stage stationary blade row includes a cooling medium flow path through which the cooling medium flows in each stationary blade in the first stage stationary blade row.   The geothermal turbine according to claim 1, wherein the cooling unit that cools the first stage stationary blade row includes a cooling medium flow path provided inside a blade attachment portion that supports the first stage stationary blade row.   2. The geothermal turbine according to claim 1, wherein the heating unit that heats the rear-stage stationary blade row includes a cooling medium flow path through which the cooling medium flows in each stationary blade in the stationary blade row. A decompression expansion unit is interposed in the cooling medium forward path from the cooling unit to the heating unit in the cooling medium circulation unit, and the gas phase component of the cooling medium after depressurization is reduced by depressurizing the cooling medium from the cooling unit. The geothermal turbine according to claim 1, wherein the liquid phase component of the cold medium after decompression is joined to the cold medium return path from the heating unit to the cooling unit while being supplied and condensed. .

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