JP2010133315A - Geothermal turbine device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress hampering of sealability or reduction of thickness caused by corrosion of a gland part, by reducing a content of a corrosive material such as H<SB>2</SB>S and CO<SB>2</SB>in steam for a gland seal introduced into a gland part having a labyrinth seal of a geothermal turbine. <P>SOLUTION: The geothermal turbine device includes: a geothermal turbine rotary-driven by geothermal steam supplied through a main steam pipe; a shaft of the geothermal steam penetrating a turbine casing; and a shaft seal part in which the labyrinth seal to which steam for seal is supplied is applied to the shaft. As steam for seal, clean steam condensate made by removing the corrosive material from the geothermal turbine after drive of a geothermal turbine drive is heated and evaporated by branched main steam branched from the main steam pipe, and is supplied to the labyrinth seal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a geothermal turbine that is rotationally driven by geothermal steam supplied through a main steam pipe, a shaft of the geothermal turbine that penetrates a turbine casing, and a labyrinth seal that is supplied with seal steam. The present invention relates to a geothermal turbine device including a shaft seal portion.

  A geothermal turbine introduces steam (geothermal steam) heated by underground magma into a working fluid to obtain rotational power. Such geothermal turbines are used, for example, in power generation facilities.

A power generation facility using a geothermal turbine will be described with reference to FIG. FIG. 5 is a system diagram of a power generation facility using a conventional geothermal turbine.
Steam (geothermal steam) heated by underground magma is led to the ground by the well 102, and earth and sand, water, etc. are separated by passing through the separator 104, and the steam component is taken out as main steam. The main steam is guided to the geothermal turbine 108 via the main steam line 106, and the rotor 112 is rotated to operate the generator 112. The steam obtained by rotating the rotor 110 by the geothermal turbine 108 is guided to the condenser 114, cooled and condensed to become water (condensate). A part of the condensate is further cooled through a circulating water line 120 including a circulating water pump 116 and a cooling tower 118 and used as cooling water for cooling the steam in the condenser 114, and used as the cooling water. The condensate that was not returned is returned to the basement.

  The main steam line 106 is branched to a main steam branch line 122, and a part of the main steam flowing through the main steam line 106 flows to the main steam branch line 122. The steam that has flowed to the main steam branch line 122 is pressure-adjusted by a gland pressure regulator 124 as gland seal steam, and a front gland 182 and a rear gland equipped with a labyrinth seal of the geothermal turbine 108 via a gland seal steam supply pipe 126 It is led to 184 and used for the ground seal. The steam used for the gland seal is led to a gland condenser 130 via a gland seal steam extraction pipe 128, cooled and condensed to become water, and led to the condenser 114.

  In this way, the technique of using the steam flowing through the main steam branch line branched from the main steam line as the ground seal steam is not limited to the geothermal turbine, but is a technique in the steam turbine. Yes.

JP 2001-140606 A

However, since the main steam in the geothermal turbine 108, that is, the steam used for the ground seal is a steam obtained by separating the earth and sand, water, and the like through the separator 104 as described above, hydrogen sulfide (H ₂ S) is contained in the steam. Corrosive gases such as carbon dioxide (CO ₂ ) and corrosive substances such as sodium chloride are contained.

Since the ground portion of the geothermal turbine 108 is at a lower temperature than the main steam used for the ground seal, a part of the steam is condensed and drained when the main steam is supplied. When a large amount of drain is generated, corrosive gases such as H ₂ S and CO ₂ contained in the main steam (geothermal steam) are dissolved in the drain, causing corrosion such as pitting corrosion in the rear ground 84, and sealing performance is improved. There were problems such as hindering steam leakage and reducing the reliability of the turbine rotor due to thinning.

Therefore, in view of the problems of the prior art, the present invention reduces the content of corrosive substances such as H ₂ S and CO ₂ in the gland seal steam introduced into the gland portion provided with the labyrinth seal of the geothermal turbine, An object of the present invention is to provide a geothermal turbine apparatus capable of suppressing the hindering of the sealing performance and the thinning due to the corrosion at the ground portion.

In order to solve the above problems, in the present invention, a geothermal turbine that is rotationally driven by geothermal steam supplied via a main steam pipe, a shaft of the geothermal turbine that penetrates the turbine casing, and a seal steam that seals the shaft. In a geothermal turbine device comprising a shaft seal portion made of a supplied labyrinth seal,
Purified condensate from which corrosive substances have been removed from the geothermal steam after the geothermal turbine is driven is converted into heated steam by the branched main steam branched from the main steam pipe and supplied to the labyrinth seal.

Steam obtained by vaporizing clean condensate from which corrosive substances have been removed from the geothermal steam after the geothermal turbine is driven is contained in the steam, such as H ₂ S, CO _2, etc., compared to the geothermal steam conventionally used as the ground seal steam. Corrosive gases such as sodium chloride and corrosive substances such as sodium chloride are significantly reduced. Therefore, by using the vapor obtained by vaporizing the clean condensate as the gland seal steam, H ₂ S, CO in the gland seal steam introduced into the gland portion (shaft seal portion) provided with the labyrinth seal of the geothermal turbine. The content of corrosive substances such as No. ₂ can be greatly reduced, and hindering of sealing performance and thinning due to corrosion at the ground portion (shaft seal portion) can be suppressed.

  Further, the use of steam obtained by vaporizing the purified condensate as steam with a greatly reduced content of corrosive substances can solve the problem without significant modification of equipment.

Further, the pH of the clean condensate is adjusted to the alkali side, and the clean condensate whose pH has been adjusted is heated and vaporized by the branched main steam branched from the main steam pipe and supplied to the labyrinth seal.
Thereby, steam with higher cleanliness can be stably supplied to the gland part provided with the labyrinth seal of the geothermal turbine, and the corrosion resistance of the gland part can be further enhanced. The effect is large when the pH of the clean condensate is adjusted to about 9 to 11 by adjusting the pH.

In addition, the main steam is mixed with the clean condensate to such an extent that the anticorrosive property of the labyrinth seal does not affect, and the mixed condensate is heated and vaporized by the branched main steam branched from the main steam pipe, thereby the labyrinth. It is characterized by supplying the seal.
Thereby, while reducing the corrosion of the gland | grand | ground part provided with the labyrinth seal, the usage-amount of the vapor | steam which vaporized clean condensate can be reduced, and the loss of the heat | fever required for the said vaporization can be reduced.

As described above, according to the present invention, the content of corrosive substances such as H ₂ S and CO ₂ in the gland seal steam introduced into the gland portion equipped with the labyrinth seal of the geothermal turbine is reduced, and the gland portion It is possible to provide a geothermal turbine apparatus capable of suppressing the hindering of the sealing performance and the thinning due to the corrosion.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

FIG. 1 is a system diagram of a geothermal turbine facility according to the first embodiment.
Steam (geothermal steam) heated by underground magma is led to the ground by a well (not shown), and earth and sand, water, etc. are separated by passing through a separator (not shown), and the steam is taken out as main steam. It is. The main steam is guided to the geothermal turbine 8 through the main steam line 6 to rotate the rotor 10. The steam obtained by rotating the rotor 10 by the geothermal turbine 8 is guided to the condenser 14, cooled and condensed to become water. Further, a gas extraction device 32 is connected to the condenser 14, and corrosion of H ₂ S, CO _{2 and the} like contained in the steam led from the geothermal turbine 8 to the condenser 14 by the gas extraction device 32. Sex gas is extracted from the condenser 14. The extracted gas is discharged from the upper part of the condenser 14.

  A part of the water (hereinafter referred to as “clean condensate”), which is led to the condenser 14 and cooled and condensed, is further cooled via a circulating water line 20 including a circulating pump 16 and a cooling tower 18 to be further recovered. 14 and used to cool the steam led from the geothermal turbine 8 to the condenser 14 and the remaining clean condensate is returned underground.

  The main steam line 6 is branched to the main steam branch line 22, and by opening a valve 40 provided on the main steam branch line 22, a part of the main steam flowing through the main steam line 6 is the main steam. It flows to the branch line 22. The steam that has flowed to the main steam branch line 22 exchanges heat with clean condensate in a circulating water branch line 34 to be described later in a heat exchanger 33, vaporizes the clean condensate, and then is sent to the condenser 14. Then, the rotor 10 is rotated by the geothermal turbine 8 and is cooled and condensed together with the steam guided to the condenser 14 to be purified condensate again.

  The circulating water line 20 is branched to the circulating water branch line 34 on the downstream side of the circulation pump 16 and the upstream side of the cooling tower 18, and by opening a valve 36 provided on the circulating water branch line 34, A part of the clean condensate flowing through the circulating water line 20 flows to the circulating water branch line 34. The purified condensate that has flowed into the circulating water branch line 34 is heated by heat exchange with the main steam flowing through the main steam branch line 22 in the heat exchanger 33, and is vaporized to become steam. The steam is guided to the front gland 82 and the rear gland 84 provided with the labyrinth seal of the geothermal turbine 8 through the gland seal steam supply pipe 26 as gland seal steam and used for the gland seal. A check valve 38 is provided on the gland seal steam supply pipe 26 to prevent backflow of steam. The steam used for the gland seal is guided to the condenser 14 via the gland seal steam extraction pipe 28, and is cooled together with the steam guided to the condenser 14 by rotating the rotor 10 by the geothermal turbine 8. Condensate again to become clean condensate.

  The branch position of the circulating water branch line 34 is not particularly limited as long as it is in the circulating water line 20, but the purified condensate flowing in the circulating water line 20 is converted by the heat exchanger 33 into the main steam branch line 22. Therefore, when the heat exchange efficiency in the heat exchanger 33 is taken into consideration, the clean condensate before being cooled by the cooling tower 18 is converted into the heat exchanger 33. As shown in FIG. 1, it is preferable to branch the circulating water branch line 34 from the circulating water line 20 on the upstream side of the cooling tower 18 as shown in FIG.

  The flow rate of the clean condensate and the main steam branching to the circulating water branch line 34 and the main steam branch line 22 is the amount of steam vaporized from the clean condensate necessary for ground sealing the front gland 82 and the rear gland 84. The flow rate adjusting method is not particularly limited as long as it is possible. As a method of adjusting the flow rate, for example, the valve 36 is opened at a constant opening so that the amount of clean condensate converted from the amount of steam necessary for supplying to the front gland 82 and the rear gland 84 flows stably to the circulating water branch line 34. In addition, a thermometer for measuring the temperature of the steam flowing through the gland seal steam supply pipe 26 is provided, and the opening degree is adjusted by using the valve 40 as a temperature control valve so that the thermometer reaches a specified temperature. For example, adjusting the flow rate of the main steam flowing.

The geothermal turbine 8 will be described with reference to FIG. 2 with reference to FIG. FIG. 2 is a configuration diagram of the geothermal turbine 8.
In FIG. 2, reference numeral 10 denotes a rotating rotor, to which a plurality of turbine blades (moving blades) 11 are attached. A turbine casing 86 is provided so as to cover the entire rotor blade 11, and the rotor 10 penetrates the turbine casing 86. Further, a front gland 82 and a rear gland 84 each provided with a labyrinth seal are provided on the main steam inlet side and the outlet side from the main steam line 6 of the turbine casing 86. The front gland 82 and the rear gland 84 leak the main steam introduced into the turbine casing 86 to rotate the rotor from the gap between the rotating turbine rotor 10 and the stationary turbine casing 86. This is provided in order to prevent air from flowing into the turbine casing 86.

In the front gland 82, a suction port for sucking steam flowing through the main steam branch line 22 is provided on the turbine casing 86 side closer to the turbine inner side, and a negative pressure from the atmospheric pressure is set on the turbine casing side closer to the outside air side. By providing a suction port connected to the ground condenser 30, the structure is configured to suck outside air and main steam leaking from the inside of the turbine. As a result, the front gland 82 is sealed by the resistance of the gland seal steam passing through the labyrinth seal.
Further, the rear gland 84 is provided with a supply port for supplying gland seal steam adjusted to a positive pressure from the exhaust pressure of the turbine from the gland seal steam supply pipe 26 on the turbine casing side closer to the turbine inner side. By providing a suction port connected to the ground condenser 30 that is adjusted from the atmospheric pressure to the negative pressure via the ground seal steam extraction pipe 28 on the passenger compartment side, the outside air and main steam leaking from the inside of the turbine are sucked in. It has a structure to do. As a result, the rear gland 84 is sealed by the resistance of the gland seal steam passing through the labyrinth seal.

In this way, clean condensate in which corrosive gases such as H ₂ S and CO ₂ contained in the steam guided to the condenser 14 are extracted by the gas extraction device 32 connected to the condenser 14. A part of the steam is heated and vaporized by the branched main steam branched from the main steam line 6 and supplied to the front gland 82 and the rear gland 84, thereby suppressing the hindering of the sealing performance and the thinning due to corrosion at the gland. be able to.
The clean condensate obtained by the condenser 14 has a significantly low content of the corrosive gas because the gas extractor 32 extracts corrosive gases such as H ₂ S and CO ₂ contained in the steam. Therefore, by using the steam obtained by vaporizing the clean condensate using the heat exchanger 33 as the ground seal steam, the H ₂ S, CO _2, etc. in the ground seal steam to be introduced into the ground portion of the geothermal turbine are used. The content of the corrosive substance is remarkably small, so that it is possible to suppress the hindering of the sealing property and the thinning due to the corrosion at the front gland 82 and the rear gland 84.

  In addition, the clean condensate obtained by the condenser 14 is partially cooled by a cooling tower to cool the condenser 14, and the clean condensate other than for cooling has been returned to the basement. It exists. Therefore, it is not necessary to make major modifications to the facilities by evaporating the clean condensate existing from the past and using it as steam.

FIG. 3 is a system diagram of the geothermal turbine facility according to the second embodiment.
The same code | symbol as the geothermal turbine installation which concerns on Example 1 shown in FIG. 1 represents the same thing, The description is abbreviate | omitted.
In the second embodiment, in addition to the configuration of the geothermal turbine facility according to the first embodiment shown in FIG. 1, it is on the circulating water branch line 34, downstream of the valve 36 and upstream of the heat exchanger 33. A water storage tank 42 and a pH adjuster 44 attached to the condensate storage tank 42 are provided.

  In FIG. 3, a part of the clean condensate flowing through the circulating water line 20 flows into the circulating water branch line 34 by opening a valve 36 provided on the circulating water branch line 34. The purified condensate that has flowed to the circulating water branch line 34 is temporarily stored in the condensate storage tank 42, and a pH adjuster is introduced by a pH adjuster attached to the condensate storage tank 42, so that the alkali side (pH 9 to 11). Adjusted to The pH-adjusted clean condensate is heat-exchanged with the steam flowing through the main steam branch line 22 by the heat exchanger 33 and is warmed and vaporized to become steam. The steam is guided to the front ground 82 and the rear ground 84 of the geothermal turbine 8 through the ground seal steam supply pipe 26 as ground seal steam and used for the ground seal.

Thus, as in the first embodiment, the gas extraction device 32 connected to the condenser 14 extracts corrosive gases such as H ₂ S and CO ₂ contained in the steam guided to the condenser 14. Since the vapor | steam which vaporized a part of the clean condensate is supplied to the front gland | grand | ground 82 and the rear gland | grand | ground 84, the obstruction | occlusion of the sealing performance by the corrosion in a gland | grand | ground part, thinning etc. can be suppressed.

Further, by providing the condensate storage tank 42, steam can be stably supplied to the front gland 82 and the rear gland 84 even if the amount of clean condensate flowing through the circulating water line 20 varies.
Furthermore, by providing the pH adjuster 44, steam with higher cleanliness can be stably supplied to the front gland 82 and the rear gland 84 of the geothermal turbine 8, and the corrosion resistance of the gland is further enhanced. be able to. The effect is large when the pH of the clean condensate is adjusted to about 9 to 11 by adjusting the pH.

FIG. 4 is a system diagram of the geothermal turbine facility according to the third embodiment.
The same code | symbol as the geothermal turbine installation which concerns on Example 1 shown in FIG. 1 represents the same thing, The description is abbreviate | omitted.
In the third embodiment, in addition to the configuration of the geothermal turbine facility according to the first embodiment shown in FIG. 1, a second main steam branch line 52 that branches the main steam line 6 on the downstream side of the main steam branch line 22. The main steam that flows through the second main steam branch line 52 and the steam that the purified condensate that flows through the circulating water branch line 34 is vaporized in the heat exchanger 33 are mixed to form the front ground 82 and the rear ground 84. It is supplied as steam for ground sealing.

First, the flow of the main steam branch will be described.
In FIG. 4, a part of the main steam flowing through the main steam line 6 flows into the main steam branch line 22 by opening the valve 40 provided on the main steam branch line 22. The main steam that has flowed to the main steam branch line 22 is heat-exchanged with the clean condensate that flows through the circulating water branch line 34 by the heat exchanger 33, vaporizes the clean condensate, and then sent to the condenser 14.

  Further, the main steam line 6 is branched to the second main steam branch line 52 on the downstream side of the main steam line 22, and the valve 54 provided on the second main steam branch line 52 is opened to open the main steam line 6. A part of the main steam flowing in the steam line 6 flows to the second main steam branch line 52. The main steam that has flowed to the second main steam branch line 52 is adjusted in pressure by the gland pressure regulator 46 and mixed with the vapor from which the purified condensate is vaporized, and is supplied to the front of the geothermal turbine 8 via the gland seal steam supply pipe 26. It is led to the part ground 82 and the rear ground 84 and used for the ground seal.

Next, the flow of branching of circulating water (clean condensate) will be described.
In FIG. 4, a part of the clean condensate flowing through the circulating water line 20 flows into the circulating water branch line 34 by opening a valve 36 provided on the circulating water branch line 34. The purified condensate that has flowed to the circulating water branch line 34 is heated by heat exchange with the steam that flows through the main steam branch line 22 in the heat exchanger 33 and is vaporized to become steam. The steam is sent via line 48 to a ground pressure regulator 46. The steam sent to the ground pressure regulator 46 is mixed with the main steam sent from the second main steam branch line 52 to the ground pressure regulator 46, and the front ground of the geothermal turbine 8 through the ground seal steam supply pipe 26. 82 and the rear gland 84 are used for gland seals.

  The mixing ratio of the main steam to the steam vaporized from the clean condensate is set so as not to affect the corrosion resistance of the front gland 82 and the rear gland 84, and it is necessary not to mix a large amount of the main steam. .

Thus, as in the first and second embodiments, the gas extraction device 32 connected to the condenser 14 corrodes H ₂ S, CO _{2 and the} like contained in the steam guided to the condenser 14. Since the vapor | steam which vaporized a part of the clean condensate which extracted the property gas is supplied to the front gland | grand | ground 82 and the rear gland | grand | ground 84, obstruction | occlusion of the sealing performance by the corrosion in a gland | grand | ground part, thinning etc. can be suppressed.

  Furthermore, since the main steam is mixed with the steam vaporized from the clean condensate, the required amount of steam vaporized from the clean condensate can be reduced, and the loss of heat required for vaporizing the clean condensate can be reduced. it can.

Reduces the content of corrosive substances such as H ₂ S and CO ₂ in the gland seal steam introduced into the gland equipped with the labyrinth seal of the geothermal turbine, hinders sealability due to corrosion at the gland and reduces the thickness It can utilize as a geothermal turbine apparatus which enabled it to suppress these.

1 is a system diagram of a geothermal turbine facility according to Embodiment 1. FIG. It is a block diagram of a geothermal turbine. It is a systematic diagram of the geothermal turbine equipment which concerns on Example 2. FIG. It is a systematic diagram of the geothermal turbine equipment which concerns on Example 3. FIG. It is a systematic diagram of the power generation equipment using the conventional geothermal turbine.

Explanation of symbols

6 Main steam line (main steam pipe)
8 Geothermal turbine 10 Rotor (shaft)
14 Condenser 20 Circulating Water Line 22 Main Steam Branch Line 26 Gland Seal Steam Supply Pipe 28 Gland Seal Steam Extraction Pipe 32 Gas Extractor 33 Heat Exchanger 34 Circulating Water Branch Line 42 Condensate Storage Tank 44 pH Controller 82 Previous Part ground (shaft seal)
84 Rear gland (shaft seal)

Claims (3)

A geothermal turbine that is rotationally driven by geothermal steam supplied through a main steam pipe, a shaft of the geothermal turbine that penetrates the turbine casing, and a shaft seal portion that is formed by a labyrinth seal that is supplied with seal steam. In a geothermal turbine device comprising:
A geothermal heat characterized in that clean condensate from which corrosive substances have been removed from geothermal steam after driving a geothermal turbine to the seal steam is heated and steamed by a branched main steam branched from the main steam pipe and supplied to the labyrinth seal. Turbine device.   2. The pH of the clean condensate is adjusted to the alkali side, and the pH-adjusted clean condensate is heated and vaporized by a branched main steam branched from the main steam pipe and supplied to the labyrinth seal. The geothermal turbine device described.   The main steam is mixed with the clean condensate to such an extent that the anticorrosive property of the labyrinth seal does not affect, and the mixed condensate is heated and steamed by the branched main steam branched from the main steam pipe to form the labyrinth seal. The geothermal turbine device according to claim 1, wherein the geothermal turbine device is supplied.

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