JP2014206085A - Axial flow turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve high nozzle efficiency over the whole area of a varying pressure ratio in an axial flow turbine in which a pressure ratio of working fluid between a nozzle blade inlet and a nozzle blade outlet is drastically varied.SOLUTION: Nozzle chambers 16a-16d are provided in such a manner of surrounding a turbine rotor 14, and working fluid w is supplied from working fluid supply pipes 22a-22d to the nozzle chambers 16a-16d. Flow control valves 26a-26d are respectively provided in the working fluid supply pipes 22a-22d. The flow control valves 26a-26d are opened and closed by a control device 28. A nozzle blade group constituted by nozzle blades having different shapes is provided for each of the nozzle chambers so that reduction of nozzle efficiency can be prevented in correspondence with different pressure ratios of nozzle inlet pressure and nozzle outlet pressure of the working fluid w.

Description

  The present invention is suitable for an axial flow turbine in which the pressure ratio of the working fluid at the inlet and outlet of the nozzle blades varies greatly depending on operating conditions, and includes a turbine nozzle that can maintain high nozzle efficiency even when the pressure ratio varies. The present invention relates to an axial flow turbine.

In the axial turbine, the working fluid is introduced from the working fluid supply pipe into the first stage turbine rotor blade through an annular introduction path provided with a turbine nozzle. And axial-flow turbine used as a power of underwater equipment, in a DSS (days start stop) axial flow turbine provided in the power plant, the inlet (leading edge) of the nozzle blade that constitutes the turbine nozzle pressure P ₁ and the outlet (after edge) pressure ratio between the pressure _{P 2 (P 1 / P 2} ) is varied significantly. Under operating conditions where the pressure ratio increases and the flow rate of the working fluid reaches the supersonic region, a tapered-diverging nozzle blade with a small energy loss (pressure loss) in the supersonic region is generally used.

  FIG. 7 (A) is a diagram schematically showing a tapered-diverging nozzle blade. As shown in the figure, the tapered-widest nozzle wing 1 has an inlet 1a having a wide cross-sectional area, a throat portion 1b having a minimum cross-sectional area, and an outlet 1c having a wide cross-sectional area. The working fluid w below the sonic velocity flowing in from the inlet 1a increases in speed and depressurizes as the nozzle cross-sectional area decreases. Under certain conditions, the sound velocity (Mach M = 1) is reached at the throat 1b. Thereafter, as the cross-sectional area increases, the working fluid w is depressurized (expanded) and becomes supersonic (M> 1).

  FIG. 7B is a diagram schematically showing a tapered nozzle blade. As shown in the figure, the tapered nozzle blade 3 has an inlet 3a having the widest cross-sectional area and an outlet 3b having the narrowest cross-sectional area. The flow velocity of the working fluid w is the fastest at the outlet 3b, but is not supersonic. Accordingly, the tapered nozzle blade is used for subsonic speed or transonic speed.

However, when the pressure ratio (P ₁ / P ₂ ) fluctuates widely from 1 to 30, in a turbine nozzle that uses only supersonic-compatible nozzle blades, the flow rate of the working fluid drops below subsonic speed during partial load operation. As a result, the nozzle efficiency is greatly reduced.
FIG. 8 shows an example of the shape and arrangement of the tapered-divergent nozzle blades 5 constituting the turbine nozzle. In FIG. 8, the point t indicates the throat portion between the nozzle blades where the gap area is the narrowest between the nozzle blades. The ratio (b / a) between the clearance area (throat area) a of the throat t and the clearance area b of the nozzle blade outlet in the tapered-diverged nozzle blade is referred to as an AR value.

FIG. 9 shows an example of the pressure ratio (P ₁ / P ₂ ) of the working fluid in the turbine nozzle. In the figure, the critical point corresponds to the throat t. The working fluid flowing between the nozzle blades expands (depressurizes) while accelerating, and the pressure ratio increases. The nozzle efficiency is best when the pressure ratio is Po at the nozzle blade outlet. In an axial turbine having a large fluctuation range of the pressure ratio during operation, the shape of the nozzle blade is designed in accordance with the supersonic region (region D). However, with this nozzle blade shape, when the pressure ratio at the nozzle blade outlet becomes a value in the region B (subsonic region) or region C (transonic region), a shock wave is generated and the nozzle efficiency is lowered.

  In Patent Document 1, an annular introduction path provided with a turbine nozzle is divided into two in the radial direction, and the working fluid is introduced into only one introduction path during partial load operation where the flow rate of the working fluid is small. A configuration for ensuring pressure and flow velocity is disclosed. In this configuration, when the annular introduction path is divided in the circumferential direction and the working fluid is introduced into only some of the introduction paths, a sudden flow change occurs at the boundary of these introduction paths, resulting in excessive impact on the turbine blades. This is used to prevent the turbine blades from being damaged due to the applied force.

  Patent Document 2 discloses an axial turbine in which the annular introduction path is divided in the circumferential direction to form a plurality of nozzle chambers. This axial flow turbine ensures the pressure and flow velocity of the working fluid by restricting the opening area of a part of the nozzle chamber where the pressure of the working fluid decreases, and prevents the nozzle efficiency (regulator stage efficiency) from decreasing. I have to.

JP-A-60-69213 Utility Model No. 2601200

  As described above, in an axial flow turbine in which the pressure ratio varies widely during operation, it is difficult to maintain high nozzle efficiency over the entire pressure ratio. The configurations disclosed in Patent Document 1 and Patent Document 2 do not solve this problem.

  In the axial flow turbine in which the pressure ratio of the working fluid between the nozzle blade inlet and the nozzle blade outlet fluctuates greatly, the present invention enables high nozzle efficiency in the entire range of the varying pressure ratio. With the goal.

  The axial flow turbine of the present invention includes a turbine nozzle in which nozzle blade groups are arranged in a line around the turbine rotor, and a turbine rotor blade group that is part of the turbine rotor and is disposed adjacent to the turbine nozzle. And a working fluid supply path that supplies the working fluid to the turbine rotor blade group via the turbine nozzle.

  In order to achieve the object, the turbine nozzle is divided into a plurality of nozzle chambers formed by dividing an annular space formed around the turbine rotor into a plurality of circumferential directions of the turbine rotor, and a plurality of nozzle chambers. Nozzle blades that are provided and have different shapes for each nozzle chamber and can prevent a decrease in nozzle efficiency corresponding to different pressure ratios of the nozzle inlet pressure and nozzle outlet pressure of the working fluid or different flow rates of the working fluid. It consists of groups. And the flow control mechanism which controls the flow volume of the working fluid supplied to each nozzle chamber, and the control apparatus which controls a flow control mechanism by the operating condition of an axial flow turbine are provided.

  With this configuration, the control device controls the flow rate control mechanism in response to fluctuations in the pressure ratio or flow rate of the working fluid during operation, and introduces the working fluid into the nozzle chamber having the nozzle blades with the best nozzle efficiency. To do. Thereby, even if the pressure ratio fluctuates, a high nozzle efficiency can always be obtained. Note that the flow rate control mechanism may be, for example, a flow rate control valve or a flow rate control damper provided in a working fluid supply path that supplies the working fluid to the turbine nozzle, or an open / close that opens and closes the inlet of each nozzle chamber into which the working fluid flows. A mechanism may be provided.

FIG. 1 shows the energy loss coefficient ratio of the working fluid to the flow velocity (Mach number) of the working fluid at the nozzle blade outlet (ratio of the energy loss coefficient when the minimum energy loss generated in the nozzle blade is 1.0). . In the figure, curve A is a case of a tapered nozzle blade having a large curvature, curve B is a case of a tapered nozzle blade having a small curvature, and curve C is a case of a flat back nozzle blade (FB nozzle blade). Curve D is for a tapered-splunger nozzle blade.
The tapered nozzle blade having a large curvature is a tapered nozzle blade having a shape with a large curvature on the back surface f near the nozzle blade outlet, like a nozzle blade 30a shown in FIG. The FB nozzle blade refers to a tapered nozzle blade having a straight section from the center of the nozzle blade rear exit to the outlet, that is, an infinite curvature radius, like a nozzle blade 30b shown in FIG.

  As shown in FIG. 1, when the Mach number is 0.6 or less, the taper-shaped nozzle blade having a large curvature has the least energy loss. When the Mach number is 0.6 to 1.0, the energy of the tapered nozzle blade having a small curvature is small. The least loss. Further, when the Mach number is 1.0 to 1.4, the energy loss of the tapered nozzle blade is the smallest, and when the Mach number is 1.4 or more, the energy loss of the tapered-divergent nozzle blade is the smallest.

  As one aspect of the present invention, all the nozzle blades provided in the plurality of nozzle chambers can be constituted by a tapered-diverging nozzle blade for supersonic speed. The tapered-diverged nozzle blade has a different area ratio (AR value) between the throat area and the outlet gap area for each nozzle chamber, and the AR value of the nozzle blade provided in each nozzle chamber has a plurality of different values. The nozzle efficiency can be set to a value that can be reduced corresponding to each pressure ratio.

  The said aspect is an aspect applied when a working fluid becomes a supersonic speed between nozzle blades. The taper-diverging nozzle blades have different AR values that provide the best nozzle efficiency depending on the pressure ratio. According to this aspect, by introducing the working fluid into the nozzle chamber having the nozzle blades with the best nozzle efficiency with respect to the pressure ratio during operation, high nozzle efficiency is always obtained even if the pressure ratio varies. be able to.

As another aspect of the present invention, all the nozzle blades provided in each nozzle chamber are set so that the variation in the outlet outflow angle when the working fluid flows into the turbine blade is within ± 10 degrees. ing.
Thereby, the pressure loss of the working fluid when the working fluid flows into the turbine rotor blade can be suppressed, and the decrease in nozzle efficiency can be prevented.

As another aspect of the present invention, all the nozzle blades provided in the plurality of nozzle chambers are composed of tapered nozzle blades for subsonic speed, and the outlet back curvature of the tapered nozzle blade is different for each nozzle chamber. Can be. This aspect is applied when the working fluid has subsonic speed including transonic speed between the nozzle blades.
In this way, by changing the outlet back curvature of the tapered nozzle blade for each nozzle chamber, the shape of the nozzle blade can correspond to a plurality of different pressure ratios for each nozzle chamber, thereby preventing a decrease in nozzle efficiency. Can be. Then, by introducing the working fluid into the nozzle chamber having the nozzle blade that minimizes the energy loss of the working fluid according to the flow velocity of the working fluid between the nozzle blades, the working fluid is always kept in place even if the pressure ratio fluctuates. Energy loss can be suppressed and nozzle efficiency can be maintained high.

  As yet another aspect of the present invention, among the plurality of nozzle chambers, the nozzle blades provided in one nozzle chamber are configured with a tapered-divergent nozzle blade for supersonic speed, and are provided in the other nozzle chambers. The nozzle blade can be formed of a tapered nozzle blade for subsonic speed.

  The turbine nozzle having such a configuration is suitable for a DSS axial flow turbine provided in a power plant. In the DSS axial flow turbine, when the load fluctuates between 75% and 100%, the flow rate of the working fluid in some nozzle chambers is reduced to a small flow rate. Therefore, in the nozzle chamber with a small flow rate, the working fluid has a high pressure ratio between the nozzle blades and is supersonic. When a tapered nozzle blade for subsonic speed is provided in such a small flow rate nozzle chamber, a shock wave is generated and pressure loss increases. Therefore, the nozzle efficiency of the nozzle chamber can be improved by making the nozzle blade of the nozzle chamber into a tapered-diverging nozzle blade for ultrasonic waves.

  In yet another aspect of the present invention, among the plurality of nozzle chambers, the nozzle blades provided in one nozzle chamber are configured with a tapered-divergent nozzle blade for supersonic speed and provided in the other nozzle chamber. The nozzle blades thus formed can be configured with a tapered nozzle blade for transonic speed, and the nozzle blades provided in the remaining nozzle chambers can be configured with a tapered nozzle blade for subsonic speed.

  When the load is reduced to around 50% in the DSS axial flow turbine, the working fluid has a smaller flow rate. Therefore, even a part of the nozzle chamber provided with the subsonic nozzle blades corresponding to the subsonic speed has a high pressure ratio and a small flow rate, so that a shock wave is easily generated and the nozzle efficiency is lowered. Therefore, by substituting the tapered nozzle blade for subsonic speed provided in the nozzle chamber having a small flow rate with the tapered nozzle blade for transonic speed, the generation of shock waves can be suppressed and the nozzle efficiency can be increased. .

  In addition, the taper type nozzle blade for transonic response can be easily manufactured by making the back surface of the exit area of the working fluid a flat surface. Therefore, the manufacturing cost of the tapered nozzle for transonic response can be reduced.

  Yet another aspect of the present invention is suitable for an axial turbine mounted on a ship. In this aspect, the first exhaust gas discharged from the main engine of the ship that drives the propulsion shaft of the ship is supplied as a working fluid to a part of the plurality of nozzle chambers to drive the generator mounted on the ship. The second exhaust gas discharged from the auxiliary engine is supplied to the other nozzle chamber as a working fluid. In this embodiment, the distinction is made not by the difference in shape as in the tapered-diverging nozzle or the tapered nozzle, but by the difference in the throat area of the nozzle blades.

  That is, the throat area of the nozzle blades provided in the plurality of nozzle chambers for the first exhaust gas is made larger than the throat area of the nozzle blades provided in the nozzle chamber for the second exhaust gas. In the case of exhaust gas with a large flow rate such as the first exhaust gas, nozzle efficiency can be improved by introducing it into a nozzle chamber provided with nozzle blades having a large throat area. On the other hand, since the exhaust gas discharged from the auxiliary engine has a small flow rate, the nozzle efficiency can be maintained high by introducing it into a nozzle chamber provided with nozzle blades having a smaller throat area. In this case, it does not matter whether the shape of the nozzle blades is a tapered-diverging nozzle blade or a tapered nozzle blade.

  According to the present invention, even an axial turbine having a large fluctuation in the pressure ratio or flow rate of the working fluid can always be operated with high nozzle efficiency.

It is a diagram which shows the energy loss coefficient ratio of the nozzle blade of various shapes. It is a longitudinal section of an axial flow turbine concerning a 1st embodiment of the present invention. It is the schematic diagram seen from the arrow E direction in FIG. (A) is a cross-sectional view of a tapered-divergent nozzle blade having a large AR value, and (B) is a cross-sectional view of a tapered-divergent nozzle blade having a small AR value. (A) And (B) is a cross-sectional view of the taper type | mold nozzle blade from which an exit back surface curvature differs. It is a schematic diagram of the axial flow turbine which concerns on 5th Embodiment of this invention. (A) is a schematic diagram of a taper-diverging nozzle, and (B) is a schematic diagram of a tapering-diverging nozzle. FIG. 3 is a cross-sectional view of a tapered-suehiro type nozzle blade. It is a diagram which shows the pressure ratio of the working fluid between nozzle blades.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
A first embodiment of the present invention will be described with reference to FIGS. 2 and 3, the axial turbine 10 </ b> A according to the present embodiment is mounted on an underwater device for power, for example. A turbine rotor 14 is provided at the inner center of the inner casing 12. Four nozzle chambers 16 a to 16 d are provided between the inner casing 12 and the turbine rotor 14 so as to surround the turbine rotor 14. The nozzle chambers 16a to 16d are fixed to the inner casing 12, and a nozzle blade group including a large number of nozzle blades is provided inside the nozzle chambers 16a to 16d. A large number of turbine rotor blade groups 20 constituting a part of the turbine rotor 14 are radially attached so as to be adjacent to and face the nozzle chambers 16a to 16d.

Working fluid supply pipes 22a to 22d are connected to the nozzle chambers 16a to 16d, respectively. The working fluid supply pipes 22a to 22d are provided with flow control valves 26a to 26d, respectively.
FIG. 3 is a schematic diagram of the nozzle chambers 16a to 16d viewed from the direction of the arrow A. FIG. 3 schematically shows the outlet openings 24a to 24d of the working fluid supply pipes 22a to 22d connected to the nozzle chambers 16a to 16d, respectively. The opening / closing operation of the flow control valves 26 a to 26 d is controlled by the control device 28.

  The turbine blade group 20 is arranged in the circumferential direction of the turbine rotor 14, but the nozzle blades provided in the nozzle chambers 16 a to 16 d are also arranged in the circumferential direction of the turbine rotor 14, similarly to the turbine blade group 20. Has been placed. The nozzle chambers 16 a to 16 d are opened facing the turbine blade group 20. Each nozzle chamber is provided with nozzle blades having different shapes. In other words, this is applied when the flow velocity of the working fluid is Mach number 1.4 or more, and the nozzle blades provided in each nozzle chamber are all tapered-stoe-wide nozzle blades for ultrasonic waves. However, each nozzle chamber has a shape with a different AR value (nozzle blade outlet clearance area b / throat part t throat area a).

  FIG. 4 shows a tapered-divergent nozzle blade used in this embodiment. In the figure, (A) shows a tapered-diverging nozzle blade 18a having a large AR value, and FIG. 4 (B) shows a tapered-diverging nozzle blade 18b having a small AR value.

Opening and closing operation of the flow control valve 24a~24d is by the control device 28 is controlled according to the pressure ratio _(P 1 / P _2). The working fluid w flows into one of the nozzle chambers 16a to 16d from one of the working fluid supply pipes 22a to 22d, and further flows from the nozzle chamber to the turbine blade group 20. The AR value that provides the best nozzle efficiency varies depending on the pressure ratio (P ₁ / P ₂ ) during operation. Therefore, the control device 28 opens the flow control valve of the nozzle chamber provided with the nozzle blades 18 that can obtain the best nozzle efficiency in accordance with the pressure ratio. As a result, the best nozzle efficiency can be obtained even if the pressure ratio fluctuates during operation.

Further, since the variation of the outlet outflow angle c of all the nozzle blades 18 in the nozzle chambers 16a to 16d is set to be within ± 10 degrees, the operation is performed when the working fluid w flows into the turbine blade group 20. The pressure loss of the working fluid w when the fluid w flows into the turbine blade group 20 can be minimized.
In this embodiment, a flow rate control damper may be provided instead of the flow rate control valves 26a to 26d, or an opening / closing mechanism for opening / closing each nozzle chamber into which the working fluid w flows is provided. By controlling with the control device 28, the working fluid w may be selectively introduced into any of the nozzle chambers 16a to 16d.

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to FIG. The configuration of the axial turbine according to this embodiment has the same configuration as that of the first embodiment except for the shape of the nozzle blades provided in the nozzle chambers 16a to 16d. Unlike the first embodiment, this embodiment is applied when the Mach number is 1.4 or less. FIG. 5 shows the shape of the nozzle blade used in the present embodiment.

Nozzle blades 30a and 30b shown in FIGS. 5A and 5B are tapered nozzle blades corresponding to subsonic speed. The tapered nozzle blade 30a and the nozzle blade 30b have different curvatures at the nozzle blade outlet rear surface f according to the Mach number of the working fluid w.
The tapered nozzle blade 30a is a tapered nozzle blade having a large curvature, the back surface f near the nozzle blade outlet has a positive curvature, and the tapered nozzle blade 30b is a flat back nozzle (FB nozzle). It has a straight section from the center of the rear exit to the exit, that is, the curvature is infinite.
The four nozzle chambers 16a to 16d are provided with tapered nozzle blades each having a shape with a different outlet back curvature.

  When the flow velocity of the working fluid is subsonic as in this embodiment, the efficiency decreases with the supersonic-capable taper-divergent nozzle used in the first embodiment. Efficiency is obtained. Further, as shown in FIG. 5, by adjusting the curvature of the back surface of the nozzle outlet, nozzle blades with good nozzle efficiency can be used according to the Mach number even when the Mach number is 1.4 or less.

  In the present embodiment, the working fluid w is introduced into a nozzle chamber having nozzle blades with the least energy loss in accordance with the Mach number of the working fluid w generated at the nozzle blade outlet. Thereby, even if the pressure ratio varies, the nozzle efficiency can always be maintained high. Further, since the variation of the outlet outflow angle c of all the nozzle blades is set within ± 10 degrees, the pressure loss of the working fluid w flowing into the turbine blade group 20 can be minimized. .

(Embodiment 3)
Next, a third embodiment of the present invention will be described. This embodiment is an embodiment suitable for a DSS axial flow turbine for adjusting electric power load. Also in this embodiment, the nozzle chamber is divided into four nozzle chambers 16a to 16d, as in the first and second embodiments. The nozzle chambers 16a to 16d are not all tapered nozzles corresponding to subsonic speeds as in the second embodiment, and the nozzle blades provided in the nozzle chambers 16a to 16c are all tapered nozzle blades corresponding to subsonic speeds. Only the nozzle blades provided in the nozzle chamber 16d are tapered and divergent nozzle blades for ultrasonic waves. Further, it is desirable that the outlet outflow angles c of all the nozzle blades be unified regardless of the nozzle shape so as to suppress an increase in the incidence loss and other losses in the turbine blade 20.

  In the DSS axial flow turbine, during operation, all the flow control valves 26a to 26d are opened, and the working fluid w is introduced into the nozzle chambers 16a to 16d. Most of the operation is partial load operation (the working fluid w flows in 100% in the nozzle chambers 16a to 16c, and the inflow amount of the working fluid w is adjusted in the nozzle chamber 16d). Therefore, in the load operation of 75 to 100%, the nozzle chamber 16d is mostly in a low flow state during operation, and the working fluid w is operating at supersonic speed.

  Therefore, by providing the nozzle chamber 16d with a tapered-diverging nozzle blade for supersonic speed, the nozzle efficiency can be maintained high. In the nozzle chamber 16d, the closer to 100% load operation, the higher the pressure ratio and the smaller the flow rate. Therefore, the flow velocity of the working fluid w becomes a supersonic region, and shock waves are generated in the tapered nozzle blades, resulting in a decrease in nozzle efficiency. Therefore, in the nozzle chamber 16d, nozzle efficiency can be maintained high by making the nozzle blades into tapered and divergent nozzle blades for ultrasonic waves.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. In the DSS axial flow turbine, when the load is about 50%, the nozzle chamber other than the nozzle chamber 16d (for example, the nozzle chamber 16c) is also operated with the flow rate of the working fluid w reduced. For this reason, in the nozzle chamber 16c, the Mach number of the working fluid w increases, and when the nozzle chamber 16c is provided with a tapered nozzle blade for subsonic speed, the pressure loss due to the shock wave increases and the nozzle efficiency decreases. Therefore, in this embodiment, a tapered nozzle (nozzle blade 30b in FIG. 5B) that can cope with transonic speed is provided. Other configurations are the same as those of the third embodiment.

  Thereby, the nozzle efficiency of the nozzle chamber 16c can be improved even at 50% load. Note that, when the load is 75 to 100%, the flow rate of the working fluid w is not reduced in the nozzle chamber 16c, so the Mach number is low. For this reason, if the nozzle chamber 16c is provided with a tapered-diverged nozzle blade for ultrasonic waves, the nozzle efficiency is greatly reduced at 75 to 100% load. Therefore, the tapered nozzle 30b for transonic speed has a higher nozzle efficiency. It does not decline.

  Further, in the present embodiment, the nozzle chambers 16a and 16b having a large inflow amount of the working fluid w are arranged facing the turbine rotor 14 and the nozzle chambers 16c and 16d having a small inflow amount of the working fluid w are disposed in the turbine rotor 14. It is arranged in the opposite direction across the. Therefore, the balance of the force of the working fluid w striking the turbine rotor blade 20 can be made uniform in the circumferential direction of the turbine rotor 14, so that vibration of the turbine rotor blade 20 can be prevented.

(Embodiment 5)
Next, an embodiment in which the present invention is applied to an axial flow turbine mounted on a ship will be described with reference to FIG. In FIG. 6, a main engine 40 and an auxiliary engine 42 are mounted. The propulsion unit 44 is driven by the main engine 40 and the generator 46 is driven by the auxiliary engine 42 to supply power in the ship. The axial turbine 10B according to the present embodiment has four nozzle chambers 16a to 16d. The nozzle chambers 16a and 16b are extended long in the circumferential direction of the turbine rotor 14, are formed to have a large volume, and a high-pressure and large-flow working fluid can flow in. On the other hand, the nozzle chambers 16c and 16d are shorter in the circumferential direction than the nozzle chambers 16a and 16b, have a small volume, and are configured such that a low-pressure and small flow rate working fluid flows in.

  The exhaust gas passage 48 provided in the main engine 40 is connected to the supply pipes 22a and 22b, and the exhaust gas discharged from the main engine 40 can be supplied to the nozzle chambers 16a and 16b. Further, the exhaust gas passage 50 provided in the auxiliary engine 42 is connected to the supply pipes 22c and 22d, and the exhaust gas discharged from the auxiliary engine 42 can be supplied to the nozzle chambers 16c and 16d.

  In the present embodiment, as in the first to third embodiments, the difference is not the difference in the shape of the tapered-diverging nozzle blade or the tapered nozzle blade, but the difference in the throat area of the nozzle blade. is there. That is, the high-pressure and large-flow exhaust gas discharged from the head engine 40 is introduced into the nozzle chambers 16a and 16b provided with nozzle blades having a large throat area, and the low-pressure and small-flow exhaust gas discharged from the auxiliary engine 42. Is introduced into the nozzle chambers 16c and 16d provided with nozzle blades having a smaller throat area.

  Further, a generator (not shown) is connected to the turbine rotor 14 of the axial flow turbine 10 </ b> B so that power can be generated by the rotation of the turbine rotor 14. The control device 28 performs opening / closing operations of the flow control valves 24a to 24d. The outlet outflow angle c of all the nozzle blades is set to an angle at which the incidence loss in the turbine blade 20 is minimized.

  In such a configuration, the axial turbine 10 </ b> B is driven by the excess exhaust heat of the main engine 40 and the auxiliary engine 42 to enable power generation. Thus, the excess exhaust heat generated by the main engine 40 and the auxiliary engine 42 can be effectively utilized for power recovery by the single axial turbine 10B. Further, since the exhaust gas discharged from the main engine 40 has a large pressure and flow rate, the nozzle efficiency is improved by supplying the nozzle chambers 16a and 16b having nozzle blades having a large throat area into which a large flow rate of exhaust gas can flow. it can. On the other hand, since the exhaust gas discharged from the auxiliary engine 42 has a small pressure and flow rate, the nozzle efficiency can be maintained high by supplying it to the nozzle chambers 16c and 16d provided with the nozzle blades having a smaller throat area than the nozzle blades.

  According to the present invention, in an axial turbine in which the pressure ratio varies widely during operation, high turbine efficiency can be maintained over the entire pressure ratio.

DESCRIPTION OF SYMBOLS 1, 5 Tapered-snow-wide nozzle blade 1a Inlet 1b Throat 1c Outlet 3 Tapered nozzle blade 3a Inlet 3b Outlet 10A, 10B Axial flow turbine 12 Inner casing 14 Turbine rotor 16a-16d Nozzle chamber 18a, 18b Tapered nozzle blade 20 Turbine blade group 22a-22d Working fluid supply pipe 24a-24d Outlet opening 26a-26d Flow rate control valve 28 Control device 30a, 30b Tapered nozzle blade 40 Main engine 42 Auxiliary engine 44 Propeller 46 Generator 48, 50 Exhaust passage a Throat area b Outlet clearance area c Outlet outflow angle t Throat w Working fluid

Claims (8)

A turbine nozzle in which nozzle blade groups are arranged in a row around the turbine rotor;
A portion of the turbine rotor, and a turbine blade group disposed adjacent to the turbine nozzle;
An axial flow turbine comprising a working fluid supply path for supplying a working fluid to the turbine rotor blade group via the turbine nozzle;
The turbine nozzle is provided in a plurality of nozzle chambers formed by partitioning an annular space formed around the turbine rotor into a plurality of circumferential directions of the turbine rotor, and the nozzle chambers. A nozzle blade group that has a different shape for each, and that can prevent a decrease in nozzle efficiency corresponding to different pressure ratios of nozzle inlet pressure and nozzle outlet pressure of the working fluid or different flow rates of the working fluid. And
A flow rate control mechanism for controlling the flow rate of the working fluid supplied to the nozzle chamber;
And a control device that controls the flow rate control mechanism according to operating conditions of the axial flow turbine.   All the nozzle blades constituting the nozzle blade group provided in the plurality of nozzle chambers are configured with a tapered-diverging nozzle blade for supersonic speed, and the tapered-diverging type for each nozzle chamber. The axial flow turbine according to claim 1, wherein an area ratio between a throat area of the nozzle blade and an outlet clearance area is different.   All the nozzle blades constituting the nozzle blade group provided in the plurality of nozzle chambers are set so that the variation in outlet outlet angle when the working fluid flows into the turbine blade is within ± 10 degrees. The axial-flow turbine according to claim 1, wherein the axial-flow turbine is provided.   All the nozzle blades constituting the nozzle blade group provided in the plurality of nozzle chambers are formed of tapered nozzle blades for subsonic speed, and the outlet back surface curvature of the tapered nozzle blades is different for each nozzle chamber. The axial-flow turbine according to claim 1. Among the plurality of nozzle chambers, a nozzle blade provided in one nozzle chamber is composed of a tapered-diverging nozzle blade for supersonic speed,
2. The axial flow turbine according to claim 1, wherein the nozzle blades provided in the other nozzle chambers are tapered nozzle blades for subsonic speed. Among the plurality of nozzle chambers, a nozzle blade provided in one nozzle chamber is composed of a tapered-diverging nozzle blade for supersonic speed,
The nozzle blade provided in the other nozzle chamber is composed of a tapered nozzle blade for transonic speed,
2. The axial flow turbine according to claim 1, wherein the nozzle blades provided in the remaining nozzle chambers are tapered nozzle blades for subsonic speed.   The axial flow turbine according to claim 6, wherein the tapered nozzle blade for transonic speed has a flat back surface in a rear edge region. The axial turbine is mounted on a ship;
The first exhaust gas discharged from the main engine of the ship that drives the propulsion shaft of the ship is supplied to some of the plurality of nozzle chambers as the working fluid,
A second exhaust gas having a lower flow rate than the first exhaust gas discharged from an auxiliary engine of the ship driving a generator mounted on the ship is supplied to the other nozzle chamber as the working fluid;
The throat area of the nozzle blades constituting the nozzle blade group provided in the plurality of nozzle chambers for the first exhaust gas constitutes the nozzle blade group provided in the nozzle chamber for the second exhaust gas. The axial turbine according to claim 1, wherein the axial turbine is larger than a throat area of the nozzle blade.

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