JP2016017446A - Axial-flow turbine and power generation plant with axial-flow turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial-flow turbine including a partial outlet/inlet structure, capable of suppressing energy loss resulting from the partial outlet/inlet structure, and capable of improving efficiency.SOLUTION: An axial-flow turbine according to an embodiment comprises: a nozzle structure 20 supported by a casing; and a rotor blade structure 40 provided downstream of the nozzle structure 20 and supported by a turbine rotor rotatable with respect to the casing. The nozzle structure 20 includes nozzles 25 provided in part of a circumferential region in an annular opening portion formed between a diaphragm outer ring and a diaphragm inner ring; and a closing portion 30 provided in the other circumferential region in the annular opening portion. The closing portion 30 closes the other region and prevents a working fluid from flowing into the other region. A penetrating opening portion 50 penetrating the closing portion 30 from an upstream side surface 31 to a downstream side surface 32 is provided in the closing portion 30.SELECTED DRAWING: Figure 5

Description

  Embodiments described herein relate generally to an axial turbine and a power plant including the axial turbine.

  In recent years, in a power plant equipped with an axial turbine, it is desired to improve power generation efficiency and to suppress the generation of CO2, SOx, NOx, and other gases to suppress global warming.

  In a thermal power plant using an axial flow turbine such as a steam turbine or a gas turbine, as an effective method for improving power generation efficiency, the temperature of the working fluid supplied to the axial flow turbine, that is, the turbine inlet temperature, can be increased. Has been done.

  On the other hand, when the volume flow rate of the working fluid flowing into the axial turbine is small, it is required to reduce the throat area (minimum flow path area) between the nozzles (stationary blades). This inevitably reduces the blade height of the nozzle by design. In this case, the secondary flow becomes dominant between the nozzles, the secondary loss increases, and the performance of the axial turbine may be degraded. For this reason, when the volume flow rate of the working fluid is small, it may be difficult to suppress the secondary flow while suppressing the deterioration of the turbine performance.

  By the way, in the steam turbine, a so-called partial feed structure is applied in order to suppress the secondary flow when the volume flow rate of the working fluid is small. Usually, a plurality of nozzles are arranged over the entire circumference of the annular opening formed between the diaphragm outer ring and the diaphragm inner ring of the steam turbine, so that the working fluid flows through the entire circumference of the annular opening. It has become. On the other hand, the partial feeding is a structure in which the working fluid is allowed to flow into a partial region in the circumferential direction of the annular opening and the other region is closed. That is, as shown in FIG. 10, at least one nozzle 100 is provided in a partial region in the circumferential direction of the annular opening, and a closing portion 101 is provided in another region of the annular opening. In this case, the nozzle 101 is not provided, and the closing portion 101 is closed so that the working fluid does not flow in. In this case, the blade height of the nozzle 100 can be adjusted to be higher by changing the ratio of the region of the closing portion 101 in the annular opening. For this reason, even if the volumetric flow rate of the working fluid is small, it is possible to suppress the secondary flow and suppress the performance deterioration of the axial turbine. Such a partial feed structure is normally used suitably for the speed control stage of a steam turbine.

Japanese Patent Laid-Open No. 2-78703

  As described above, in the axial turbine having a small volume flow rate of the working fluid, the partial feed structure is often applied. However, in the partial feeding structure, an additional loss due to the partial feeding structure occurs, and the efficiency can be lowered. There are two main reasons for the decrease in efficiency.

  That is, the working fluid does not flow into the closing portion 101 provided in the annular opening. This makes it difficult for the working fluid to flow into the space between the moving blades 102 that are not positioned in the flow path of the main flow F <b> 1 that has flowed out of the nozzle 100. The working fluid having a small flow rate is filled and stays. For this reason, there is a problem that the rotational energy of the moving blade 102 is consumed to rotate the staying working fluid, and a loss occurs.

  Further, as shown in FIG. 10, the operation along the rotation direction of the moving blade 102 is dragged by the rotation of the moving blade 102 between the downstream side surface 101 a of the closing portion 101 and the upstream end 102 a of the moving blade 102. A rotation direction flow F2 of the fluid is formed, and the formed rotation direction flow F2 reaches the end portion 101b on the downstream side surface 101a of the closing portion 101 on the rotation direction side. However, the speed of the rotational flow F2 reaching the end 101b is very small. As a result, the energy of the main flow F1 of the working fluid accelerated by the nozzle 100 is consumed to accelerate the rotational flow F2 having a small speed reaching the end 101b toward the moving blade 102, resulting in loss. There is a problem that occurs.

  In this way, a new loss occurs by applying the partial feeding structure, which hinders efficiency improvement.

  The present invention has been made in consideration of such a point, and is an axial flow turbine having a partial feed structure, which improves energy efficiency by suppressing energy loss caused by the partial feed structure. It is an object of the present invention to provide an axial flow turbine capable of generating a power plant and a power plant including the same.

  An axial turbine according to an embodiment includes a nozzle structure supported by a casing, and a rotor blade structure provided on a downstream side of the nozzle structure and supported by a turbine rotor that is rotatable with respect to the casing. doing. The nozzle structure is provided in a part of the annular opening formed between the outer ring of the diaphragm and the inner ring of the diaphragm in a region in the circumferential direction and in another region of the annular opening in the circumferential direction. And a closing portion. The closing portion closes this other region and prevents the working fluid from flowing into this other region. The closing portion is provided with a through opening that penetrates from the upstream side surface to the downstream side surface of the closing portion.

  The axial turbine according to the embodiment includes a plurality of nozzle structures supported by a casing and a plurality of blade structures supported by a turbine rotor that is rotatable with respect to the casing. The nozzle structure and the rotor blade structure are alternately arranged in the axial direction of the turbine rotor. The nozzle structure is provided in a part of the annular opening formed between the outer ring of the diaphragm and the inner ring of the diaphragm in a region in the circumferential direction and in another region of the annular opening in the circumferential direction. And a closing portion. The closing portion closes this other region and prevents the working fluid from flowing into this other region. A through opening that penetrates from the upstream side surface to the downstream side surface of the closing portion is provided in the closing portion of the nozzle structure disposed on the downstream side of the moving blade structure. The through opening is arranged at a position overlapping the closing portion of the nozzle structure adjacent to the through opening on the upstream side in the circumferential direction.

  An axial turbine according to the embodiment includes a nozzle structure supported by a casing, a moving blade structure provided on a downstream side of the nozzle structure and supported by a turbine rotor that is rotatable with respect to the casing, have. The nozzle structure is provided in a part of the annular opening formed between the outer ring of the diaphragm and the inner ring of the diaphragm in a region in the circumferential direction and in another region of the annular opening in the circumferential direction. And a closing portion. The closing portion closes this other region and prevents the working fluid from flowing into this other region. The moving blade structure includes a plurality of moving blades arranged in the circumferential direction. The downstream side surface of the closing portion is formed so as to approach the upstream end of the moving blade in the rotation direction of the moving blade structure.

  Furthermore, the axial turbine according to the embodiment includes a nozzle structure supported by a casing, a moving blade structure provided on a downstream side of the nozzle structure and supported by a turbine rotor rotatable with respect to the casing, have. The nozzle structure is provided in a part of the annular opening formed between the outer ring of the diaphragm and the inner ring of the diaphragm in a region in the circumferential direction and in another region of the annular opening in the circumferential direction. And a closing portion. The closing portion closes this other region and prevents the working fluid from flowing into this other region. The moving blade structure includes a plurality of moving blades arranged in the circumferential direction. A guiding portion for guiding the working fluid between the downstream side surface and the upstream end of the moving blade to the moving blade side is provided on the downstream side surface of the closing portion.

  In addition, the power plant according to the embodiment combusts an oxygen production apparatus that extracts oxygen from the air by removing nitrogen, fuel, and oxygen extracted by the oxygen production apparatus to generate combustion gas. And the above-described axial turbine in which the combustion gas generated by the combustor is supplied as a working fluid and rotationally driven. The generator generates electricity by the rotational drive of the axial turbine. The exhaust gas discharged from the axial turbine is cooled by a cooler. The moisture in the exhaust gas cooled by the cooler is separated and removed by the moisture separator, and the exhaust gas is regenerated. The regeneration gas regenerated by the moisture separator is compressed by the compressor. In the regenerative heat exchanger, heat exchange is performed between the regenerated gas compressed by the compressor and the exhaust gas from the axial turbine toward the cooler. The regeneration gas heat-exchanged by the regeneration heat exchanger is supplied to the combustor.

FIG. 1 is a diagram showing an overall configuration of a power plant according to a first embodiment of the present invention. FIG. 2 is an overall view showing an example of an axial turbine used in the power plant of FIG. FIG. 3 is a partial cross-sectional view of the axial turbine of FIG. FIG. 4 is a view of the nozzle structure of FIG. 3 as seen from the axial direction of the turbine rotor. FIG. 5 is a view showing a section of a turbine stage corresponding to the line XX in FIG. 3. FIG. 6 is a diagram showing a cross section of a turbine stage similar to FIG. 5 in the second embodiment of the present invention. FIG. 7 is a view showing a cross section of a turbine stage similar to FIG. 5 in the third embodiment of the present invention. FIG. 8 is a diagram showing a modification of FIG. FIG. 9 is a view showing a cross section of a turbine stage similar to FIG. 5 in the fourth embodiment of the present invention. FIG. 10 is a diagram showing a cross section of a turbine stage similar to that of FIG. 5 in an axial turbine having a general partial insertion structure.

(First embodiment)
The axial turbine and the power plant including the axial turbine according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

  First, the power plant 1 will be described with reference to FIG.

  As shown in FIG. 1, the power plant 1 includes an oxygen production apparatus 2 that extracts oxygen from air by removing nitrogen, a combustor 3 that generates combustion gas, and a combustion gas generated by the combustor 3. And an axial turbine 10 having a turbine rotor 12 (see FIG. 2) that is supplied as a working fluid and rotationally driven.

  Among these, the oxygen extracted by the oxygen production apparatus 2 is supplied to the combustor 3, and the combustor 3 burns this oxygen and fuel to generate combustion gas. It has become. Examples of the fuel used in the combustor 3 include natural gas containing no nitrogen such as methane gas. Since combustion of fuel uses air from which nitrogen has been removed, that is, oxygen, the combustion gas generated in the combustor 3 contains CO 2 gas and water vapor. That is, the components of the combustion gas are CO2 (carbon dioxide) and water. For this reason, it can suppress that gases, such as SOx (sulfur oxide) and NOx (nitrogen oxide), are contained in combustion gas.

  In the combustor 3, high-temperature combustion gas is generated. For example, it is preferable that combustion gas of 600 ° C. or higher is generated. As a result, it is possible to improve the power generation efficiency and suppress the generation amount of gas such as CO2. The combustor 3 is supplied with a regeneration gas (specifically, CO 2 gas, that is, a gas containing CO 2 as a component) heated in the regeneration heat exchanger 5 from a regeneration heat exchanger 5 described later. The fuel is burned together with the supplied regeneration gas.

  Combustion gas generated by the combustor 3 is supplied to the axial flow turbine 10 as a working fluid, performs work on a moving blade 41 (see FIG. 3) described later, and rotationally drives the turbine rotor 12. A generator 4 is connected to the turbine rotor 12 of the axial flow turbine 10, and the generator 4 generates power when the turbine rotor 12 is rotationally driven.

  The combustion gas that has worked in the axial flow turbine 10 is discharged from the axial flow turbine 10 as exhaust gas. The exhaust gas contains CO2 gas and water vapor. That is, the components of the exhaust gas are also CO2 and water. The exhaust gas is supplied to the regenerative heat exchanger 5 provided on the downstream side of the axial turbine 10. In addition, the regeneration heat exchanger 5 is supplied with a relatively low temperature regeneration gas from a CO2 pump (compressor) 8 described later. Thereby, in the regeneration heat exchanger 5, the regeneration gas and the exhaust gas exchange heat, and the relatively high temperature exhaust gas is cooled.

  A cooler 6 is provided on the downstream side of the regenerative heat exchanger 5. The cooler 6 is supplied with the exhaust gas cooled from the regenerative heat exchanger 5, and the cooler 6 further cools the exhaust gas.

  A moisture separator 7 is provided on the downstream side of the cooler 6. The moisture separator 7 is supplied with the exhaust gas cooled by the cooler 6, and the moisture separator 7 separates and removes moisture from the exhaust gas. Thus, moisture is removed from the exhaust gas containing CO2 and water as components, and the exhaust gas is regenerated. That is, the exhaust gas is regenerated into a regenerated gas as a gas containing CO 2 as a component.

  A CO2 pump 8 is provided on the downstream side of the moisture separator 7. The regeneration gas regenerated by the moisture separator 7 is supplied to the CO2 pump 8, and the CO2 pump 8 compresses the regeneration gas to increase the pressure of the regeneration gas.

  The compressed regeneration gas is supplied to the regeneration heat exchanger 5 described above. In the regenerative heat exchanger 5, heat exchange is performed between the regenerated gas compressed by the CO 2 pump 8 and the exhaust gas from the axial turbine 10 toward the cooler 6 as described above. Thereby, the relatively low temperature regeneration gas is heated. A part of the regeneration gas compressed by the CO 2 pump 8 is recovered without being supplied to the regeneration heat exchanger 5. The recovered regeneration gas is stored or used for other purposes (for example, for increasing the amount of oil drilling).

  The regeneration gas heated by the regeneration heat exchanger 5 is supplied to the combustor 3.

  As described above, in the power plant 1 shown in FIG. 1, power generation is performed using a combustion gas of 600 ° C. or higher that includes CO2 generated by combustion and water as components, and most of the CO2 is circulated and reused. Is done. As a result, the volume flow rate of the working fluid can be increased, and the generation of NOx and SOx that are harmful gases can be prevented. Moreover, the equipment for separating and recovering CO2 from the exhaust gas can be eliminated. Furthermore, the purity of the recovered CO2 can be increased, and it can be used for various purposes other than power generation.

  Next, the axial flow turbine 10 in this Embodiment is demonstrated using FIG. Here, an example of a high-pressure turbine in which the pressure of the combustion gas is relatively high is shown as the axial flow turbine 10.

  As shown in FIG. 2, the axial turbine 10 includes a casing 11 and a turbine rotor 12 provided to be rotatable with respect to the casing 11. Among these, the casing 11 has an inner casing 11a and an outer casing 11b provided outside the inner casing 11a, and has a double structure.

  A gas supply pipe 13 is connected to the outer casing 11b, and the combustion gas generated in the combustor 3 is supplied to the axial flow turbine 10 as a working fluid. The working fluid supplied to the axial turbine 10 is guided to the most upstream turbine stage 15 among a plurality of turbine stages 15 to be described later by an inlet sleeve 14 a and a nozzle box 14 b provided in the casing 11. It has become. The above-described generator 4 is connected to the turbine rotor 12.

  A plurality of nozzle structures 20 are supported on the casing 11 (more specifically, the inner casing 11a). A plurality of blade structures 40 are supported on the turbine rotor 12. The nozzle structures 20 and the rotor blade structures 40 are alternately arranged in the axial direction of the turbine rotor 12. One turbine stage 15 is configured by one nozzle structure 20 and one blade structure 40 arranged adjacent to the downstream side of the one nozzle structure 20. The axial turbine 10 is provided with a plurality of such turbine stages 15 in the axial direction of the turbine rotor 12. In this way, the working fluid supplied through the gas supply pipe 13 passes through the plurality of turbine stages 15 to perform work on the rotor blade 41, and the turbine rotor 12 is rotationally driven. Yes.

  The working fluid that has passed through the rotor blade 41 in the final stage is discharged to the outside of the axial turbine 10 through the exhaust passage 16.

  Next, the nozzle structure 20 will be described with reference to FIGS. 3 and 4.

  As shown in FIG. 3, the nozzle structure 20 includes a diaphragm outer ring 21 supported by the casing 11, and a diaphragm inner ring 22 provided on the inner peripheral side from the diaphragm outer ring 21. As shown in FIGS. 3 and 4, an annular opening 23 extending in the circumferential direction is formed between the diaphragm outer ring 21 and the diaphragm inner ring 22. The diaphragm outer ring 21 is fitted and fixed to the casing 11.

  A labyrinth packing 24 is provided on the inner peripheral surface of the diaphragm inner ring 22. The labyrinth packing 24 is for preventing the working fluid from flowing downstream and leaking between the diaphragm inner ring 22 and the turbine rotor 12.

  As shown in FIG. 4, a plurality of nozzles (static blades) 25 are provided in a partial region in the circumferential direction of the annular opening 23 described above. The plurality of nozzles 25 are arranged in a row in the circumferential direction in the region. A region where the nozzle 25 is disposed forms a nozzle opening 26, and the working fluid is fed into the nozzle opening 26 and flows into the nozzle opening 26.

  A closing portion 30 is provided in another region of the annular opening 23 in the circumferential direction. The closing part 30 is for closing the other region and preventing the working fluid from flowing into the region. Such a structure is called a partial delivery structure. The partial feed structure is preferably applied to each nozzle structure 20. In this case, it is preferable that the closing portions 30 of the nozzle structures 20 that are adjacent to each other via the moving blade structure 40 are arranged so as to be shifted from each other in the circumferential direction. Further, as shown in FIG. 5, the end surface on the rotational direction side of the moving blade 41 of the closing portion 30 (the end surface on the right side in FIG. 5) has the same shape as the negative pressure surface of the nozzle 25, and adjacent nozzles The nozzle 25 is separated from the nozzle 25 by a nozzle pitch T. The end surface (the end surface on the left side in FIG. 5) opposite to the rotation direction side of the closing portion 30 has the same shape as the pressure surface of the nozzle 25 and is formed away from the adjacent nozzle 25 by the nozzle pitch T. Has been.

  In this way, a partial feeding structure is formed in which the working fluid is fed into a part of the annular opening 23. In addition, the closing part 30 can be comprised by the plate-shaped member attached to the annular opening part 23. FIG.

  Next, the moving blade structure 40 will be described with reference to FIG.

  As shown in FIG. 3, the moving blade structure 40 has a plurality of moving blades 41. That is, the turbine rotor 12 is provided with a rotor disk 12a projecting to the outer peripheral side, and the rotor blades 41 are implanted and fixed to the rotor disk 12a. The plurality of moving blades 41 are arranged in the circumferential direction. When such a moving blade 41 receives work from the working fluid, rotational energy is obtained and the turbine rotor 12 rotates.

  A snubber 42 is provided at the outer peripheral end portion of the moving blade 41. The snubber 42 is for suppressing the vibration of the turbine rotor 12. Seal fins 43 are arranged on the outer peripheral surface of the snubber 42. The seal fin 43 prevents the working fluid from flowing downstream and leaking between the diaphragm outer ring 21 (more specifically, a portion extending to the moving blade 41 side of the diaphragm outer ring 21) and the snubber 42. Is for. The seal fins 43 are preferably provided on the diaphragm outer ring 21.

  Next, the through opening 50 provided in the closing portion 30 will be described with reference to FIG.

  As shown in FIG. 5, the closing portion 30 is provided with a through opening 50 that penetrates from the upstream side surface 31 to the downstream side surface 32 of the closing portion 30. The through opening 50 forms a through opening flow F3 for supplying the working fluid to the downstream blade 41 instead of the main flow F1 passing through the nozzle 25, and the working fluid upstream of the closing portion 30 is moved to the blade. 41 side. In FIG. 5, the through opening 50 is formed so as to extend along the axial direction of the turbine rotor 12, and forms a through opening flow F <b> 3 along the axial direction.

  The circumferential position of the through opening 50 is not particularly limited, but is preferably arranged as follows. That is, in order to prevent the main flow F1 of the working fluid that has been accelerated and flowed out by the nozzle 25 from being obstructed, it is preferable to secure a certain distance in the circumferential direction from the nozzle 25. On the other hand, in the space between the downstream side surface 32 of the closing portion 30 and the upstream end 41a of the moving blade 41, the through-flow flow F3 effectively forms the rotating flow F2 along the rotating direction of the moving blade 41. In order to suppress, it is preferable that the circumferential distance from the nozzle 25 is not so large.

を満たしていることが好適である。 In order to achieve such an object, the through opening 50 is preferably arranged as follows. That is, as shown in FIG. 5, the through opening 50 is preferably arranged on the side opposite to the rotation direction side of the moving blade 41 in the closing portion 30. Further, the throat (minimum distance between nozzles 25) between adjacent nozzles 25 is S, the pitch (circumferential distance) of the nozzles 25 is T, and the axis between the downstream side surface 32 of the closing portion 30 and the upstream end 41a of the moving blade 41. When the directional distance is B, and the circumferential distance between the downstream end 25a of the nozzle 25 arranged on the most rotational direction side (the leftmost side in FIG. 5) and the through opening 50 (the center thereof) is A, A is

It is preferable that

で一般的に表される。この関係を用いることにより、［数１］の関係を求めることができる。すなわち、この流出角度αで主流Ｆ１が軸方向に距離Ｂだけ進んだ場合、周方向に進む距離は、

となる。 By the way, the outflow angle α of the main flow F1 flowing out from the nozzle 25 (the inclination angle of the main flow F1 with respect to the rotation direction of the moving blade 41) is determined using the throat S and the pitch T described above.

It is generally expressed as By using this relationship, the relationship of [Equation 1] can be obtained. That is, when the main flow F1 advances by the distance B in the axial direction at the outflow angle α, the distance to advance in the circumferential direction is

It becomes.

  The main flow F1 also flows out from between the downstream end 25a of the nozzle 25 on the most rotational direction side and the end 32a on the downstream side surface 32 of the closing portion 30 opposite to the rotational direction side. As described above, the end portion 32a is formed at a position shifted by the pitch T from the downstream end 25a of the nozzle 25 on the most rotational direction side. Thus, in order to prevent the main flow F1 flowing out from the vicinity of the end portion 32a from being obstructed by the through-opening flow F3, the value obtained by adding the pitch T of the nozzle 25 to [Equation 3] is the circumferential direction. It can be a suitable lower limit value of the distance A.

  On the other hand, in order to effectively suppress the formation of the rotational flow F2 described above, the value obtained by further adding the pitch T of the nozzles 25 to the lower limit value obtained as described above is the circumferential distance A. Can be a suitable upper limit value.

  In this way, [Equation 1] described above can be obtained.

  Incidentally, in FIG. 5, the through opening 50 is formed in a tapered shape toward the downstream side, and the flow passage cross-sectional area of the through opening 50 gradually decreases from the upstream side toward the downstream side (for example, a conical shape). The example is formed in a trapezoidal shape. In this case, the through-opening flow F3 can be accelerated to increase the speed of the through-opening flow F3. Note that a plurality of the through openings 50 described above may be provided in the closing portion 30 of one nozzle structure 20. Furthermore, each nozzle structure 20 may be provided in the closing portion 30.

  Next, the operation of the present embodiment having such a configuration will be described.

  When combustion gas as working fluid is supplied from the combustor 3 shown in FIG. 1 to the axial turbine 10 via the gas supply pipe 13 (see FIG. 2), the supplied working fluid is supplied to the inlet sleeve 14a and the nozzle box. 14b is supplied to the most upstream turbine stage 15. The supplied working fluid performs work on the moving blade 41 of the turbine stage 15 (see FIGS. 3 and 5), and then also works on the moving blade 41 of each turbine stage 15 on the downstream side. . In this way, the turbine rotor 12 is rotationally driven.

  During this time, the working fluid of 600 ° C. or higher is fed into the nozzle openings 26 (see FIG. 4) of the nozzle structure 20 of each turbine stage 15, passes between the nozzles 25, and flows out from the nozzles 25.

  Most of the working fluid in the main flow F <b> 1 that has flowed out of the nozzle 25 flows into the space between the moving blades 41, but part of the working fluid flows between the downstream side surface 32 of the closing portion 30 and the upstream end 41 a of the moving blade 41. It flows into the space and tries to form a rotational flow F2 along the rotational direction.

  However, in the present embodiment, the working fluid flows out from the through opening 50 provided in the closing portion 30 to the moving blade 41 side to form the through opening flow F3. As a result, the rotational flow F2 described above can be guided to the side of the moving blade 41 to flow into the space between the moving blades 41, and the rotational flow F2 flows along the rotational direction of the moving blade 41. It can suppress effectively continuing. It is also possible to recover the power of the rotational flow F2. Furthermore, by forming the through-opening flow F3, the working fluid staying in the space between the moving blades 41 not positioned in the flow path of the main flow F1 can be guided and flowed downstream.

  Thus, according to the present embodiment, it is possible to form the through-opening flow F3 in which the working fluid flows out from the through-opening 50 provided in the closing portion 30. As a result, the working fluid staying between the moving blades 41 can flow to the downstream side, and the rotation energy of the moving blades 41 can be prevented from being consumed to rotate the staying working fluid. . Further, it is possible to effectively suppress the formation of the rotational flow F2 along the rotational direction of the moving blade 41 in the space between the downstream side surface 32 of the closing portion 30 and the upstream end 41a of the moving blade 41. It is possible to prevent the energy of the main flow F <b> 1 accelerated and discharged by the nozzle 25 from being consumed to guide the rotational flow F <b> 2 toward the moving blade 41. For this reason, the energy loss resulting from the partial insertion structure can be suppressed, and the efficiency can be improved.

(Second Embodiment)
Next, an axial flow turbine and a power plant provided with the axial flow turbine according to the second embodiment of the present invention will be described with reference to FIG.

  The second embodiment shown in FIG. 6 is mainly different in that the through-opening is provided in the closing portion of the nozzle structure disposed on the downstream side of the moving blade structure. These are substantially the same as those of the first embodiment shown in FIGS. In FIG. 6, the same parts as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 6, in the present embodiment, the closing portion 30 of the nozzle structure 20 disposed on the downstream side of the moving blade structure 40 penetrates from the upstream side surface 31 to the downstream side surface 32 of the closing portion 30. A through opening 60 is provided. The through opening 60 draws out the working fluid staying between the upstream moving blades 41 and supplies the working fluid to the downstream moving blade 41 side instead of the main flow F1 passing through the nozzle 25. A flow F3 is formed. By drawing out the working fluid remaining between the upstream moving blades 41 in this way, a space is formed between the downstream side surface 32 of the upstream closing portion 30 and the upstream end 41 a of the moving blade 41. The rotational flow F2 along the rotational direction is guided between the moving blades 41, and the rotational flow F2 can be prevented from coming into contact with the main flow F1.

  Such a through opening 60 is provided not in the closing part 30 of the first turbine stage 15 but in the closing part 30 of the turbine stage 15 on the downstream side of the first turbine stage 15. If the turbine stage 15 is downstream of the first turbine stage 15, the through opening 60 may be provided in the closing portions 30 of the plurality of turbine stages 15. A plurality of through openings 60 may be provided in the closing portion 30 of one turbine stage 15.

  The circumferential position of the through opening 60 is not particularly limited, but is preferably arranged as follows. That is, in order to prevent the main flow F <b> 1 of the working fluid accelerated and discharged by the nozzle 25 from being obstructed by being drawn out by the through opening 60, the end portion on the rotation direction side of the downstream side surface 32 of the closing portion 30. It is preferably positioned on the side opposite to the rotational direction side from 32b. On the other hand, in order to prevent the formation of the rotational flow F2 that can come into contact with the main flow F1, it is preferable that the circumferential distance from the nozzle 25 is not so large.

  In order to achieve such an object, the through opening 60 is preferably arranged as follows. That is, as shown in FIG. 6, it is preferable that the through opening 60 is arranged at a position overlapping with the closing part 30 of the nozzle structure 20 adjacent to the through opening 60 on the upstream side in the circumferential direction. Further, the through opening 60 is disposed on the rotation direction side of the moving blade 41 in the closing portion 30, the pitch of the nozzles 25 is T, the rotation direction side end portion 32 b on the downstream side surface 32 of the upstream closing portion 30, and When the circumferential distance from the through opening 60 (the center thereof) is C, it is preferable that C satisfies T ≧ C ≧ 0.

  The through-opening 60 can have the same configuration as the through-opening 50 shown in FIG. 5 except for the configuration described above.

  As described above, according to the present embodiment, it is possible to form the through-opening flow F3 in which the working fluid flows out from the through-opening 60 provided in the downstream-side closing portion 30, and The working fluid staying in between can be drawn out. By this, the rotational flow F2 along the rotational direction formed in the space between the downstream side surface 32 of the upstream closing portion 30 and the upstream end 41a of the moving blade 41 is guided to the moving blade 41 side. Can do. For this reason, it is possible to prevent the rotational flow F2 from coming into contact with the main flow F1 that has been accelerated by the nozzle 25 and flowed out, and the energy of the main flow F1 is consumed because the rotational flow F2 is guided to the moving blade 41 side. Can be prevented. In addition, the working fluid staying between the moving blades 41 can flow to the downstream side, and the rotation energy of the moving blades 41 can be prevented from being consumed to rotate the staying working fluid. As a result, energy loss due to the partial insertion structure can be suppressed and efficiency can be improved.

  In FIG. 6 of the present embodiment described above, the upstream side closing portion 30 is not provided with the through opening 50 as shown in FIG. 5, but the present invention is not limited to this. A through-opening 50 may be provided in the closing part 30. In this case, the effect of the through-opening 50 described in the first embodiment can also be achieved, and energy loss can be further suppressed.

(Third embodiment)
Next, with reference to FIG. 7, an axial flow turbine and a power plant including the axial flow turbine according to a third embodiment of the present invention will be described.

  The third embodiment shown in FIG. 7 is mainly different in that the downstream side surface of the closing portion is formed so as to approach the moving blade structure in the rotation direction of the moving blade structure. The configuration is substantially the same as that of the first embodiment shown in FIGS. In FIG. 7, the same parts as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, in the present embodiment, the downstream side surface 32 of the closing portion 30 is formed so as to approach the upstream end 41 a of the moving blade 41 in the rotation direction of the moving blade 41. More specifically, the downstream side surface 32 of the closing portion 30 is inclined so as to gradually approach the upstream end 41a of the moving blade 41 in the rotational direction. In other words, the downstream side surface 32 is formed so as to form a part of a spiral so as to be displaced downstream in the rotational direction of the rotor blade 41.

  As a result, the distance between the downstream side surface 32 and the upstream end 41a of the rotor blade 41 can be reduced in the rotational direction, and the volume of the space between the downstream side surface 32 and the upstream end 41a is reduced. can do. For this reason, the rotational flow F2 along the rotational direction formed in the space between the downstream side surface 32 of the closing portion 30 and the upstream end 41a of the rotor blade 41 can be contracted, and the rotational flow F2 can be formed. It can be effectively suppressed.

  The downstream side surface 32 of the closing portion 30 is inclined at an inclination angle β with respect to the rotational direction of the moving blade 41. The inclination angle β is preferably substantially equal to the above-described outflow angle α of the main flow F1 flowing out from the nozzle 25. In this case, the downstream side surface 32 can be inclined along the direction of the main flow F1, the main flow F1 can be prevented from being obstructed, and the main flow F1 can be efficiently guided to the space between the moving blades 41.

  Thus, according to the present embodiment, the downstream side surface 32 of the closing portion 30 is formed so as to approach the moving blade 41 in the rotation direction of the moving blade 41. Thereby, the main flow F <b> 1 flowing out from the nozzle 25 can be effectively guided between the moving blades 41. For this reason, it is possible to effectively suppress the formation of the rotational flow F2 along the rotational direction in the space between the downstream side surface 32 of the closing portion 30 and the upstream end 41a of the rotor blade 41. It is possible to prevent the energy of the main flow F <b> 1 that has been accelerated and flowed out from being consumed to guide the rotational flow F <b> 2 toward the moving blade 41. In addition, the working fluid staying between the moving blades 41 can flow to the downstream side, and the rotation energy of the moving blades 41 can be prevented from being consumed to rotate the staying working fluid. As a result, energy loss due to the partial insertion structure can be suppressed and efficiency can be improved.

  In the present embodiment described above, for example, as shown in FIG. 8, the working fluid between the downstream side surface 32 and the upstream end 41 a of the moving blade 41 is applied to the downstream side surface 32 of the closing portion 30. A guiding portion 70 that guides to the side of the head may be provided. The guide portion 70 is disposed on the side opposite to the rotational direction side of the moving blade 41 in the closing portion 30. Further, as shown in FIG. 8, the guide portion 70 is preferably formed so as to protrude from the downstream side surface 32 of the closing portion 30 to the moving blade 41 side (downstream side). In the form shown in FIG. 8, the working fluid between the downstream side surface 32 of the closing portion 30 and the upstream end 41 a of the moving blade 41 can be more reliably guided to the moving blade 41 side. Although FIG. 8 shows an example in which two such guiding portions 70 are provided, the present invention is not limited to this, and it is sufficient that at least one guiding portion 70 is provided.

(Fourth embodiment)
Next, an axial flow turbine and a power plant provided with the axial flow turbine according to a fourth embodiment of the present invention will be described with reference to FIG.

  In the fourth embodiment shown in FIG. 9, a guiding portion that guides the working fluid between the downstream side surface and the upstream end of the moving blade to the moving blade side is provided on the downstream side surface of the closing portion. The main difference is that the side surfaces are not inclined, and the other configuration is substantially the same as that of the first embodiment shown in FIGS. In FIG. 9, the same parts as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 9, a guiding portion 70 that guides the working fluid between the downstream side surface 32 and the upstream end 41 a of the moving blade 41 toward the moving blade 41 is provided on the downstream side surface 32 of the closing portion 30. . The guide portion 70 is disposed on the side opposite to the rotational direction side of the moving blade 41 in the closing portion 30. In addition, as shown in FIG. 9, the guide portion 70 is preferably formed so as to protrude from the downstream side surface 32 of the closing portion 30 to the moving blade 14 side (downstream side).

  In the form shown in FIG. 9, the downstream side surface 32 of the closing portion 30 is not inclined and is formed substantially parallel to the upstream side surface 31 so as to follow the rotating direction of the moving blade 41.

  As described above, according to the present embodiment, the working fluid between the downstream side surface 32 and the upper end portion 41 a of the moving blade 41 is transferred to the moving blade 41 side by the guide portion 70 provided on the downstream side surface 32 of the closing portion 30. To flow into the space between the rotor blades 41. Thus, it is possible to effectively suppress the formation of the rotational flow F2 along the rotational direction in the space between the downstream side surface 32 of the upstream closing portion 30 and the upstream end 41a of the rotor blade 41. It is possible to prevent the energy of the main flow F <b> 1 accelerated and discharged by the nozzle 25 from being consumed to guide the rotational flow F <b> 2 toward the moving blade 41. In addition, the working fluid staying between the moving blades 41 can flow to the downstream side, and the rotation energy of the moving blades 41 can be prevented from being consumed to rotate the staying working fluid. As a result, energy loss due to the partial insertion structure can be suppressed and efficiency can be improved.

  According to the embodiment described above, even in an axial flow turbine having a partial feed structure, it is possible to improve efficiency by suppressing energy loss caused by the partial feed structure.

    Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof. Moreover, as a matter of course, these embodiments can be partially combined as appropriate within the scope of the present invention.

  In each of the above-described embodiments, the combustor 3 that generates combustion gas as a working fluid supplied to the axial turbine 10 burns oxygen supplied from the oxygen production apparatus 2 and fuel. The example which produces | generates combustion gas was demonstrated. However, the present invention is not limited to this, and the combustor 3 may generate combustion gas by burning air and fuel. Further, the axial turbine 10 in the above-described embodiment can be applied not only to the power plant 1 as shown in FIG. 1 but also to a power plant having an arbitrary configuration.

DESCRIPTION OF SYMBOLS 1 Power plant 2 Oxygen production apparatus 3 Combustor 4 Generator 5 Regenerative heat exchanger 6 Cooler 7 Moisture separator 8 CO2 pump 10 Axial flow turbine 11 Casing 12 Turbine rotor 20 Nozzle structure 21 Diaphragm outer ring 22 Diaphragm inner ring 23 Annular Opening portion 25 Nozzle 25a Downstream end 30 Closure portion 31 Upstream side surface 32 Downstream side surface 32a End portion 32b opposite to the rotation direction side End portion 40 in the rotation direction side 40 Blade structure 41 Moving blade 41a Upstream end 50 Through opening 60 Through opening 70 Guide part

Claims (14)

In an axial turbine having a nozzle structure supported by a casing, and a blade structure provided on a downstream side of the nozzle structure and supported by a turbine rotor rotatable with respect to the casing,
The nozzle structure is
A nozzle provided in a partial region in the circumferential direction of the annular opening formed between the diaphragm outer ring and the diaphragm inner ring;
A closing portion provided in another region in the circumferential direction of the annular opening, the closing portion closing the other region and preventing the working fluid from flowing into the other region,
The axial flow turbine according to claim 1, wherein the closing portion is provided with a through opening that penetrates from the upstream side surface to the downstream side surface of the closing portion. The moving blade structure includes a plurality of moving blades arranged in a circumferential direction,
The through opening is arranged on the side opposite to the rotation direction side in the closing portion,
The nozzle throat is S, the nozzle pitch is T, the axial distance between the downstream side surface of the closing portion and the upstream end of the moving blade is B, and is arranged closest to the rotating direction of the moving blade structure. When the circumferential distance between the downstream end of the nozzle and the through opening is A, A is

The axial turbine according to claim 1, wherein:   The axial flow turbine according to claim 1, wherein the plurality of nozzle structures and the plurality of blade structures are alternately arranged in an axial direction of the turbine rotor.   The through-opening portion of the nozzle structure disposed on the downstream side of the rotor blade structure is disposed at a position overlapping the closing portion of the nozzle structure adjacent to the through-opening on the upstream side in the circumferential direction. The axial-flow turbine according to claim 3, wherein   The pitch of the nozzle is T, the through opening, and the end of the moving blade structure on the downstream side of the closing portion of the nozzle structure adjacent to the through opening on the upstream side. The axial turbine according to claim 4, wherein when the circumferential distance is C, C satisfies T ≧ C ≧ 0. A plurality of nozzle structures supported by a casing, and a plurality of blade structures supported by a turbine rotor rotatable with respect to the casing, the nozzle structure and the bucket structure, In the axial turbine arranged alternately in the axial direction of the turbine rotor,
The nozzle structure is
A nozzle provided in a partial region in the circumferential direction of the annular opening formed between the diaphragm outer ring and the diaphragm inner ring;
A closing portion provided in another region in the circumferential direction of the annular opening, the closing portion closing the other region and preventing the working fluid from flowing into the other region,
The closing portion of the nozzle structure disposed on the downstream side of the moving blade structure is provided with a through opening that penetrates from the upstream side surface to the downstream side surface of the closing portion,
The axial flow turbine is characterized in that the through opening is arranged at a position overlapping with the closing portion of the nozzle structure adjacent to the through opening on the upstream side in the circumferential direction.   The pitch of the nozzle is T, the through opening, and the end of the moving blade structure on the downstream side of the closing portion of the nozzle structure adjacent to the through opening on the upstream side. The axial flow turbine according to claim 6, wherein when the circumferential distance is C, C satisfies T ≧ C ≧ 0. In an axial turbine having a nozzle structure supported by a casing, and a blade structure provided on a downstream side of the nozzle structure and supported by a turbine rotor rotatable with respect to the casing,
The nozzle structure is
A nozzle provided in a partial region in the circumferential direction of the annular opening formed between the diaphragm outer ring and the diaphragm inner ring;
A closing portion provided in another region in the circumferential direction of the annular opening, the closing portion closing the other region and preventing the working fluid from flowing into the other region,
The moving blade structure includes a plurality of moving blades arranged in a circumferential direction,
An axial flow turbine characterized in that the downstream side surface of the closing portion is formed so as to approach the upstream end of the moving blade in the rotational direction of the moving blade structure.   The axial flow turbine according to claim 8, wherein the downstream side surface of the closing portion is formed so as to gradually approach the upstream end of the moving blade in the rotation direction of the moving blade structure. .   9. The guide portion for guiding the working fluid between the downstream side surface and the upstream end of the moving blade to the moving blade side is provided on the downstream side surface of the closing portion. The axial flow turbine according to claim 9.   The axial flow turbine according to claim 10, wherein the guide portion is formed so as to protrude from the downstream side surface of the closing portion toward the moving blade. In an axial turbine having a nozzle structure supported by a casing, and a blade structure provided on a downstream side of the nozzle structure and supported by a turbine rotor rotatable with respect to the casing,
The nozzle structure is
A nozzle provided in a partial region in the circumferential direction of the annular opening formed between the diaphragm outer ring and the diaphragm inner ring;
A closing portion provided in another region in the circumferential direction of the annular opening, the closing portion closing the other region and preventing the working fluid from flowing into the other region,
The moving blade structure includes a plurality of moving blades arranged in a circumferential direction,
An axial flow turbine characterized in that a guiding portion for guiding the working fluid between the downstream side surface and the upstream end of the moving blade to the moving blade side is provided on the downstream side surface of the closing portion.   The axial flow turbine according to claim 12, wherein the guide portion is formed so as to protrude from the downstream side surface of the closing portion toward the moving blade. An oxygen production device that extracts oxygen from the air by removing nitrogen; and
A combustor for combusting fuel and oxygen extracted by the oxygen producing device to generate combustion gas;
The axial flow turbine according to any one of claims 1 to 13, wherein the combustion gas generated by the combustor is supplied as a working fluid and rotationally driven.
A generator for generating electric power by rotational driving of the axial flow turbine;
A cooler for cooling the exhaust gas discharged from the axial turbine;
A moisture separator that separates and removes moisture from the exhaust gas cooled by the cooler and regenerates the exhaust gas;
A compressor for compressing the regenerated gas regenerated by the moisture separator;
A regeneration heat exchanger that exchanges heat between the regeneration gas compressed by the compressor and the exhaust gas from the axial turbine toward the cooler,
The power generation plant, wherein the regeneration gas heat-exchanged by the regeneration heat exchanger is supplied to the combustor.

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