JP5329942B2 - Steam turbine - Google Patents

Description

  The present invention relates to a steam turbine capable of reducing wet loss, and more particularly to a steam turbine capable of reducing condensate loss of wet loss.

  In order to realize further improvement of the performance of the steam turbine, it is necessary to reduce the moisture loss peculiar to the steam turbine. This wet loss includes condensate loss (thermodynamic loss when micro water droplets are generated), braking loss (loss due to water droplets colliding with moving blades), acceleration loss (friction loss when steam accelerates water droplets) ) And can be classified into three losses.

Conventional methods for reducing wet loss are mainly aimed at removing moisture. Conventionally, for example, a drain catcher that effectively separates and removes water droplets blown to the outer peripheral wall surface by the centrifugal force of the moving blade, and sucks the water film formed on the nozzle blade surface and the wall surface by making the inside of the nozzle hollow Thus, the reduction of wet loss was suppressed using a slit, a drain separator, or the like that suppresses the generation of coarse water droplets (see, for example, Non-Patent Document 1).
Turbomachinery Association "Steam Turbine" pages 179-180

  However, in the conventional wet loss reduction method described above, moisture is separated and removed, which contributes to the reduction of braking loss and acceleration loss in the wet loss, but condensate loss that occurs when water droplets are generated. The effect of reducing was not obtained.

  Therefore, the present invention has been made to solve the above-described problem, and an object of the present invention is to provide a steam turbine that can reduce condensate loss and wet loss.

In order to achieve the above object, according to one aspect of the present invention, a steam turbine including a plurality of turbine stages composed of a cascade of stationary blades and moving blades, wherein a steam condition at a stage inlet is a dry region. And a fluid supply means for supplying wet steam to a turbine passage section between a turbine stage where the steam condition at the outlet of the stage is in a wet region and a turbine stage immediately upstream of the turbine stage. A steam turbine is provided.

  According to the steam turbine of the present invention, it is possible to reduce the condensate loss and reduce the wet loss.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view of a steam turbine 200 including a fluid supply unit 10 according to a first embodiment of the present invention.

  As shown in FIG. 1, the steam turbine 200 includes, for example, a double-structure casing that includes an inner casing 210 and an outer casing 211 provided outside the inner casing 210. Further, a turbine rotor 212 is provided through the inner casing 210. A plurality of turbine rotor blades 220 are implanted in the turbine rotor 212 side by side in the circumferential direction, and a plurality of stages are provided in the axial direction of the turbine rotor 212. In addition, a nozzle 230 that functions as a stationary blade is disposed on the inner surface of the inner casing 210 so as to alternate with the turbine rotor blade 220 in the axial direction of the turbine rotor 212. One nozzle stage is constituted by the nozzle blade row composed of the nozzles 230 and the rotor blade blade row composed of the turbine blades 220 immediately downstream of the nozzle blade row.

  A steam inlet pipe 214 is connected to the steam turbine 200, from which low-pressure steam is introduced into each turbine stage arranged in series.

  In addition, between the turbine stage in which the steam condition is in the dry zone at the inlet of the paragraph and in the wet zone at the outlet of the paragraph, and the turbine stage upstream of the turbine stage, there are fine particles in the steam passage between the paragraphs. Fluid supply means 10 for supplying a fluid containing

  Here, the dry region refers to a region above the saturated vapor line in the hs diagram, and the wet region refers to a region below the saturated vapor line in the hs diagram. The steam condition in the steam turbine is determined by whether the expansion line on the hs diagram in the steam turbine is in the above-described dry region or the wet region. The expansion line on the hs diagram indicates the state quantity of steam in each stage of the turbine. From the pressure and temperature in the dry area above the saturated steam line, the pressure in the wet area below the saturated steam line. The position of the expansion line can be specified from the wetness.

  Note that the configuration of the steam turbine 200 is not limited to the configuration described above. For example, the number of turbine stages and the configuration of the casing can be changed as appropriate.

  Next, the configuration of the fluid supply means 10 will be described.

  FIG. 2 shows a steam turbine 200 provided with the fluid supply means 10 according to the first embodiment of the present invention in the vicinity of the turbine stage where the steam condition is in the dry area at the paragraph inlet and in the wet area at the paragraph outlet. It is a figure which shows a cross section. Here, the steam condition is a dry zone at the inlet of the paragraph and a turbine paragraph in the wet zone at the outlet of the paragraph is indicated by 240a, this turbine stage is indicated by the turbine blades constituting the 240a, and the nozzle is indicated by 230a. Further, a turbine stage immediately upstream of the turbine stage 240a is indicated by 240b, a turbine rotor blade constituting the turbine stage 240b is indicated by 220b, and a nozzle is indicated by 230b.

  As shown in FIG. 2, the fluid supply means 10 includes an inner casing between a turbine stage 240a in which the steam condition is in a dry zone at the paragraph inlet and in a wet zone at the paragraph outlet and a turbine paragraph 240b immediately upstream thereof. A through-hole 11 formed in 210 and a pipe 12 connected to one end of the through-hole 11 and guiding a fluid containing fine particles are provided. In order to uniformly disperse the fluid containing fine particles in the vapor passage, it is preferable that a plurality of the through holes 11 and the pipes 12 are provided at predetermined intervals in the circumferential direction of the inner casing 210.

  Here, the fluid containing fine particles is composed of wet vapor or vapor containing plastic fine particles (for example, fine particles of polystyrene or polypropylene). When the fluid containing microparticles is composed of wet steam, the microparticles are water droplets. In this case, the wetness of the wet steam is preferably 0.05 or less. The reason why the wet steam has a wetness of 0.05 or less is that when the wetness exceeds 0.05, water droplets are likely to grow into coarse water droplets, resulting in increased wet loss and erosion. In addition, for the reason of easy growth of water droplets, the lower limit of the wetness of the wet steam is preferably 0.01. In addition, the average particle diameter of the water droplet contained in the wet steam is about 0.05 μm to 2 μm. The average particle diameter here is a median diameter defined by a 50% diameter of the relative particle amount. Further, the average particle diameter of the water droplets can be measured, for example, by irradiating the water droplets with laser light and using information on the intensity and angle of scattered light from the water droplets.

  On the other hand, when the fluid containing fine particles is composed of steam containing plastic fine particles, wet steam, dry saturated steam or superheated steam having a wetness of 0.05 or less is used as the steam. The average particle size of the plastic fine particles is preferably 0.1 μm to 2 μm. This average particle size range is preferable because if the average particle size is smaller than 0.1 μm, recovery of the particles may be difficult. If it is larger than 2 μm, water droplets adhering around the particles This is because the probability of growing into coarse particles having a size of 100 μm or more increases, which may cause erosion. For example, the average particle diameter of plastic fine particles such as polystyrene can be measured, for example, by irradiating the fine particles with laser light and using information on the intensity and angle of scattered light from the fine particles. Moreover, the average particle diameter here is a median diameter defined by a 50% diameter of the relative particle amount. In addition, as the plastic fine particles, it is preferable to use polystyrene particles, polypropylene particles, and the like, which have a small variation in particle size and are commercially available in various particle sizes.

  When the fluid containing fine particles is composed of vapor containing plastic fine particles, a mixing unit (not shown) for mixing the vapor and plastic fine particles on a part of the pipe 12 or upstream of the pipe 12. Is provided.

  Since the fluid containing the fine particles is ejected into the vapor passage by the fluid supply means 10, the pressure of the fluid containing the fine particles is set higher than the pressure of the main steam flowing in the vapor passage. It is preferable to set the pressure of the fluid containing fine particles to, for example, 1.05 times or more the pressure of the main steam. Moreover, as the above-described steam, for example, steam extracted from the upstream paragraph can be used.

  Next, operation | movement of the steam turbine 200 of 1st Embodiment is demonstrated.

  The low-pressure main steam flowing into the steam turbine 200 through the steam inlet pipe 214 passes through the steam passage between the nozzle 230 and the turbine rotor blade 220 of each turbine stage, and rotates the turbine rotor 212. Further, when the main steam passes through each turbine stage, the steam condition is in the dry zone at the paragraph inlet and from the other end of the through-hole 11 provided on the upstream side of the turbine paragraph 240a in the wet zone at the paragraph outlet, A fluid containing fine particles guided from the outside by the pipe 12 is ejected into the vapor passage. The fluid containing the ejected fine particles is mixed with the main steam and flows into the turbine stage 240a. Further, the steam that has performed expansion work is exhausted and guided to a condenser (not shown).

  When recovering plastic fine particles when using vapor containing plastic fine particles as a fluid containing fine particles, the fine particles contained in the condensate are centrifuged after the steam condenses in the condenser. It can be recovered by a centrifuge tank using force.

  Next, the action of the fluid containing fine particles ejected into the vapor passage by the fluid supply means 10 will be described.

  First, condensate loss will be described.

  FIG. 3 is a diagram showing the relationship between the virus line and the pressure change on an enthalpy-entropy diagram (hereinafter referred to as hs diagram).

  Generally, in a steam turbine, even when dry steam expands and reaches a wet region beyond the saturated steam line on the hs diagram, condensate of steam does not occur immediately. In FIG. 3, the dry region refers to the region above the saturated vapor line, and the wet region refers to the region below the saturated vapor line. The reason why steam condensate does not occur immediately after dry steam reaches the wet region is based on the effect of surface tension, and such steam is called supersaturated steam. The line connecting the points on the h-s diagram where the steam condensate starts from this supersaturated steam state is called the virus line, and is almost parallel to the isohumidity line.

  The virus line is influenced by the magnitude of the pressure change of the steam, and as shown in FIG. 3, the supersaturated state continues as the pressure change (ΔP) increases. Therefore, the larger the pressure change (ΔP), the more the viron line is located in a region where the wetness range is wider, that is, a region away from the saturated vapor line in the wet region. On the other hand, when the pressure change (ΔP) is small, the range of the supersaturated state is narrowed, and the virus ray is located in a region where the wetness range is narrow, that is, a region close to the saturated vapor line in the wet region. Here, the pressure change (ΔP) is expressed by the following equation (1).

                ΔP = −1 / P × (dP / dt) Equation (1)

  Here, dP / dt is the change in pressure per unit time, and P is the steam pressure in the turbine cascade.

  When condensate is generated from the supersaturated steam in the state on the virus line, heat transfer from the newly generated water droplet nucleus to the gas phase is performed. Therefore, the entropy of the gas phase is increased, resulting in a thermodynamic loss. This is called condensate loss.

  As described above, condensate loss occurs because heat transfer from newly generated droplet nuclei to the gas phase occurs when condensate starts from supersaturated steam and the entropy of the gas phase increases. Therefore, as described above, in the steam turbine according to the present invention, before the water droplet nuclei are generated in the turbine stage 240a that is in the dry zone at the paragraph inlet and in the wet zone at the paragraph outlet, A fluid containing fine particles is ejected from the upstream side by the fluid supply means 10, and the fine particles are dispersed in the main steam flowing into the turbine stage 240a.

  By flowing into the turbine stage 240a, the main steam whose steam condition has become a wet region through the saturated vapor line from the dry region condenses around the fine particle with the fine particle as a nucleus. By condensing water around the microparticles in this way, it is possible to prevent the main steam from becoming supersaturated. Therefore, it is possible to suppress the occurrence of condensate loss caused by the generation of water droplet nuclei in the supersaturated main steam.

  As described above, according to the steam turbine 200 of the first embodiment, the steam is supplied by the fluid supply means 10 from the upstream side of the turbine stage where the steam condition is in the dry zone at the paragraph inlet and in the wet zone at the paragraph outlet. By supplying a fluid containing fine particles in the passage, it is possible to prevent the main steam from being oversaturated. As a result, in the steam turbine 200 of the first embodiment, the occurrence of condensate loss is suppressed, and it is possible to reduce the wet loss.

  Note that the configuration of the steam turbine 200 according to the first embodiment is not limited to the configuration described above. For example, the fluid supply means 10 may be configured as follows as a configuration in which a fluid containing fine particles is uniformly dispersed in the vapor passage.

  FIG. 4 is a view showing a cross section near the turbine stage where the steam condition is in the dry region at the stage inlet and in the wet area at the stage outlet in the steam turbine 200 having the fluid supply means 10 of another configuration.

  As shown in FIG. 4, the fluid supply means 10 may include a tubular supply pipe 15 having a jet outlet 16 for ejecting a fluid containing fine particles, which is installed by being inserted into a vapor passage. The outlet 16 of the supply pipe 15 is formed to face the nozzle 230a of the turbine stage 240a. The direction of the jet port 16 is not limited to this, and any configuration may be used as long as the fluid containing the fine particles ejected from the jet port 16 can be uniformly mixed with the main steam flowing in the steam passage. Further, in order to uniformly mix the fluid containing fine particles into the main steam flowing in the steam passage, the supply pipe 15 has the jet outlet 16 positioned at the center of the radial length of the nozzle 230a of the turbine stage 240a, for example. It is preferable that they are arranged as described above.

  Moreover, you may equip the jet nozzle 16 with the injection nozzle which ejects the fluid containing a microparticle with a predetermined | prescribed injection angle. By providing this injection nozzle, the fluid containing fine particles is jetted at a predetermined jetting angle, so that the fluid containing fine particles can be mixed more uniformly with the main steam flowing through the steam passage. In the fluid supply means 10 described above that does not include the supply pipe 15, the above-described injection nozzle may be provided at the other end of the through-hole 11, that is, at the end of the through-hole 11 on the vapor passage side. Further, the number of the ejection ports 16 is not limited to one, and a plurality of ejection ports may be formed on the tube wall of the supply pipe 15. Thus, by providing a plurality of jet outlets, the fluid containing fine particles can be more uniformly mixed with the main steam flowing in the steam passage. Furthermore, the supply pipe 15 with the tip end closed and a plurality of jet holes formed in the pipe wall may be provided over the radial length of the nozzle 230a of the turbine stage 240a.

  In addition, a plurality of fluid supply means 10 having other configurations described above are preferably provided at predetermined intervals in the circumferential direction of the inner casing 210 in order to uniformly disperse the fluid containing fine particles in the vapor passage.

  Also in the steam turbine 200 including the fluid supply means 10 having the other configuration described above, it is possible to prevent the main steam from being oversaturated, similarly to the steam turbine 200 of the first embodiment. Thereby, in the steam turbine 200, the occurrence of condensate loss is suppressed, and the wet loss can be reduced. Furthermore, since the fluid containing microparticles can be more uniformly mixed with the main steam flowing through the steam passage, it is possible to more effectively suppress the occurrence of condensate loss.

(Second Embodiment)
In the steam turbine 200 according to the second embodiment of the present invention, the configuration of the fluid supply means is different from that of the steam turbine 200 according to the first embodiment described above. Therefore, here, the fluid supply unit 20 having a different configuration from the fluid supply unit 10 of the first embodiment will be mainly described.

  FIG. 5 shows a steam turbine 200 provided with the fluid supply means 20 according to the second embodiment of the present invention. It is a figure which shows a cross section. FIG. 6 is a view showing a cross section taken along the line AA of FIG. In addition, the same code | symbol is attached | subjected to the same part as the structure of the steam turbine 200 of 1st Embodiment, and the overlapping description is abbreviate | omitted or simplified.

  As shown in FIG. 5, the fluid supply means 20 removes fine particles formed in the nozzle 230a constituting the turbine stage 240a in which the steam condition at the paragraph inlet is in the dry region and the steam condition at the paragraph outlet is in the wet region. A jet outlet 21 for jetting out the fluid is provided. The jet port 21 is configured by, for example, a slit-shaped opening having a predetermined width and extending in the radial direction of the nozzle 230a. Moreover, the jet nozzle 21 is formed in the center part of the radial direction length of the nozzle 230a. Moreover, as shown in FIG. 6, the jet nozzle 21 is formed in the back side and the stomach side of the nozzle 230a. Moreover, the jet nozzle 21 formed on the back side is formed on the front edge side, and the jet nozzle 21 formed on the ventral side is formed on the rear edge side.

  In addition, the shape and formation position of the jet nozzle 21 are not restricted to this, What is necessary is just a structure which can eject the fluid containing a microparticle in the main steam which flows around the nozzle 230a. Furthermore, it is sufficient that at least one ejection port 21 is formed, and three or more ejection ports 21 may be formed. For example, in order to more uniformly mix the fluid containing microparticles with the main steam flowing in the steam passage, a plurality of jet nozzles 21 may be formed across the radial direction of the nozzle 230a.

  Moreover, although the jet nozzle 21 should just be formed in the at least 1 nozzle 230a among the several nozzles 230a which comprise the nozzle cascade of the turbine stage 240a, the fluid containing a microparticle is uniformly in a vapor | steam channel | path. In order to disperse, it is preferable that the nozzles 230a are formed. For example, the spout 21 may be formed every other nozzles 230a arranged in a row. Moreover, you may form the jet nozzle 21 in all the nozzles 230a arranged in a line. In addition, although the example which made the shape of the jet nozzle 21 slit shape was shown here, the shape of the jet nozzle 21 is not restricted to this. For example, it may be configured by a plurality of openings such as a circle and a rectangle. Moreover, you may equip the formed opening with the injection nozzle mentioned above.

  As shown in FIG. 6, the fluid containing fine particles guided into the hollow nozzle 230 a is ejected from the ejection port 21 into the main steam flowing around the nozzle 230 a. The main effect is that the same effect as that of the fluid containing fine particles described in the steam turbine 200 of the first embodiment is exhibited, and the steam condition passes through the saturated steam line from the dry region to become the wet region. The steam condenses around the microparticles using the microparticles as nuclei. By condensing water around the microparticles in this way, it is possible to prevent the main steam from becoming supersaturated. Therefore, it is possible to suppress the occurrence of condensate loss caused by the generation of water droplet nuclei in the supersaturated main steam.

  Here, as described above, since the fluid containing fine particles is ejected from the ejection port 21 into the vapor passage, the pressure of the fluid containing fine particles is set higher than the pressure of the main steam flowing in the vapor passage. . For example, it is preferable to set the pressure of the fluid containing fine particles to 1.05 times or more the pressure of the main vapor. Moreover, as the above-described steam, for example, steam extracted from the upstream paragraph can be used.

  As described above, according to the steam turbine 200 of the second embodiment, the nozzle 230a constituting the turbine stage 240a in which the steam condition at the paragraph inlet is in the dry region and the steam condition at the paragraph outlet is in the wet region is By providing the ejection port 21 that ejects a fluid containing fine particles, the main steam can be prevented from being oversaturated. Thereby, in the steam turbine 200, the occurrence of condensate loss is suppressed, and the wet loss can be reduced. Furthermore, since the fluid containing microparticles can be more uniformly mixed with the main steam flowing through the steam passage, it is possible to more effectively suppress the occurrence of condensate loss.

  Although the present invention has been specifically described above with reference to the embodiments, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the invention.

A sectional view of a steam turbine provided with fluid supply means of a 1st embodiment concerning the present invention. The figure which shows the cross section of the turbine stage vicinity in the steam turbine provided with the fluid supply means of 1st Embodiment which concerns on this invention in which a steam condition exists in a dry area in a paragraph inlet, and exists in a wet area in a paragraph outlet. The figure which shows the relationship between a viral line and a pressure change on an enthalpy-entropy diagram. The figure which shows the cross section of the turbine stage vicinity in which the steam conditions in a steam turbine provided with the fluid supply means of another structure are in a dry area in a paragraph inlet, and are in a wet area in a paragraph outlet. The steam turbine provided with the fluid supply means of 2nd Embodiment which concerns on this invention WHEREIN: The figure which shows the cross section of turbine stage vicinity in which steam conditions exist in a dry area in a paragraph inlet, and are in a wet area in a paragraph outlet. The figure which shows the AA cross section of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,20 ... Fluid supply means, 11 ... Through port, 12 ... Pipe, 15 ... Supply pipe, 16, 21 ... Jet port, 200 ... Steam turbine, 210 ... Inner casing, 211 ... Outer casing, 212 ... Turbine rotor, 214 ... steam inlet pipe, 220 ... turbine blade, 230, 230a ... nozzle, 240a, 240b ... turbine stage.

Claims (9)

A steam turbine comprising a plurality of turbine stages composed of a cascade of stationary and moving blades,
Fluid supplying wet steam to a turbine passage section between a turbine stage in which the steam condition at the paragraph inlet is in a dry region and the steam condition at the paragraph outlet is in a wet region, and the turbine stage immediately upstream of the turbine stage A steam turbine comprising supply means. The steam turbine according to claim 1, wherein the fluid supply means includes a through-hole formed in a casing constituting the turbine passage portion, and supplies the wet steam through the through-hole. 2. The steam according to claim 1, wherein the fluid supply means includes a tubular supply pipe formed by being inserted into the turbine passage portion and having at least one jet outlet for ejecting the wet steam. Turbine. The steam turbine according to any one of claims 1 to 3, wherein the wet steam has a wetness of 0.05 or less . The steam turbine according to claim 1, wherein an average particle diameter (median diameter) of water droplets contained in the wet steam is 0.05 μm to 2 μm . A steam turbine comprising a plurality of turbine stages composed of a cascade of stationary and moving blades,
The turbine passage section between the turbine stage where the steam condition at the stage inlet is in the dry area and the steam condition at the stage outlet is in the wet area and the turbine stage immediately upstream of the turbine stage contains plastic fine particles. A steam turbine comprising fluid supply means for supplying steam. The said fluid supply means is provided with the through-hole formed in the casing which comprises the said turbine channel | path part, The vapor | steam containing the said plastic type microparticles | fine-particles is supplied through the said through-hole . Steam turbine. The fluid supply means is provided with a tubular supply pipe formed by inserting at least one jet outlet for ejecting a vapor containing the plastic fine particles, which is inserted into the turbine passage. Item 7. The steam turbine according to Item 6 . The steam turbine according to any one of claims 6 to 8, wherein the steam is wet steam having a wetness of 0.05 or less, dry saturated steam, or superheated steam.

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