JP2015021404A - Radial turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radial turbine capable of easily discharging condensed drain from gas, and capable of improving turbine efficiency without increasing the manufacturing cost in a radial turbine allowing the gas flowing into an impeller in a radial direction through a casing suction port to flow out in an axial direction.SOLUTION: A radial turbine 1 includes a turbine casing 2, a casing suction port 3 formed in the casing 2, a gas flow passage allowing the gas sucked from the suction port 3 to inwardly flow from an outer periphery of a turbine nozzle, and an impeller having a plurality of moving blades on which the gas flowing in from the outer periphery of the turbine nozzle acts, and a center line CL of the suction port 3 is arranged in an obliquely downward direction or a directly downward direction at an angle θ less than 90 degrees with respect to a downward vertical line VL passing through an axis of a rotating shaft CA of the impeller.

Description

  The present invention includes a gas sucked from a casing suction port of a turbine casing in a radial turbine in which the gas flows in an axial direction and flows out in an axial direction to an impeller to which a plurality of moving blades are attached. The present invention relates to a radial turbine capable of easily discharging drain from the turbine casing.

  Turbines are generally classified roughly into axial flow turbines and radial turbines. Axial turbines are suitable for medium and large capacity, and almost all axial turbines are used for steam turbines in large thermal power plants. On the other hand, radial turbines have historically been developed for gas cold generation, and are intended to lower the temperature of gas by supplying gas to the turbine and expanding it. A generated expansion turbine is a typical example.

  And the heat insulation efficiency of the medium and small-sized axial flow turbines is about 40% at the maximum, whereas the radial turbine reaches 80 to 85%. This decisive difference is the greatest feature of the radial turbine, and the amount of power recovered from the gas is almost twice that of the axial flow turbine (per single stage).

  The radial turbine is configured to rotate the impeller to which a plurality of moving blades are attached by directing the gas flowing into the turbine casing through the turbine casing suction port inward in the radial direction. Was usually configured upwards.

First, problems of such a radial turbine will be described below.
In the radial turbine, the gas sucked from the casing suction port provided in the turbine casing passes through the gas flow path, and then flows into the impeller to which a plurality of moving blades are attached through the turbine nozzle. By rotating the car, the gas energy is converted into the rotational energy of the impeller. And the gas after impeller passage is discharged | emitted from a turbine casing through a discharge port.

  In a radial turbine, air, combustion gas, or superheated gas is often used as a working medium, and the gas accelerated by the turbine nozzle through the gas flow path is condensed when entering the wet region, and drain ( Condensate) is generated as droplets.

  However, when the casing suction port provided in the turbine casing is configured to face upward, the gas enters the region of the moving blade and adiabatically expands, but a part of the droplets staying in the turbine casing is moved to the moving blade. It adheres to the negative pressure surface and merges with other droplets on the negative pressure surface and becomes gradually larger. The increased droplets are blown to the outer peripheral side by the centrifugal force of the moving blade, and collide with the inward surface of the turbine nozzle at the tip peripheral speed of the moving blade. And the droplet after a collision stays as a drain in the lowest part of the gas flow path in a turbine casing.

  The collision of the liquid droplets with the turbine nozzle causes a so-called drain attack, and the nozzle surface is eroded into a fluttering shape, not only reducing the efficiency of the nozzle, but also missing a part of the nozzle, resulting in debris. There was a problem that the blades could be damaged. Moreover, the drain staying at the lowermost part of the gas flow path has also caused corrosion of the turbine casing. Further, due to the influence of the accumulated drain, problems such as a decrease in turbine performance and an increase in turbine shaft vibration may occur in the worst case.

  Next, a radial turbine according to a conventional example in which such problems are improved will be described with reference to FIG. FIG. 5 is a longitudinal sectional view showing a main part of a radial turbine according to a conventional example.

  In the radial turbine according to the conventional example, the inlet end 23a of the rotor blade 23 is inclined, and the back plate 25 of the impeller is further extended to the turbine outer peripheral side than the inlet end 23a of the rotor blade 23. A through hole 26 is provided in the portion 25a from the intersection of the rotor blade 23 and the back plate 25 as a starting point, obliquely rearward when viewed from the turbine side, and radially when viewed from the front. A droplet collector 27 is installed on the back surface of the back plate 25 so as to be positioned at the outlet of the through hole 26.

  With such a configuration, the droplets adhering to the vicinity of the inlet end 23a of the moving blade 23 are aggregated by the action of the interfacial tension and centrifugal force and the component force in the direction along the inlet end 23a of the moving blade 23, and the inlet end 23a. It flows to the back plate 25 side along the inclination. Then, the liquid droplets flowing toward the back plate 25 pass through the through-hole 26, are guided behind the nozzle 22, are once collected by the liquid droplet collector 27, and then appropriately discharged.

  As a result, the radial turbine according to the conventional example can reduce the flow return amount of the droplets to the nozzle 22 to prevent the drain attack, and extend the life of the radial turbine used under the condition where the condensate is generated. The effect of improving the reliability was obtained (see Patent Document 1).

  However, the radial turbine according to this conventional example is provided with an inclination to the inlet end 23a of the rotor blade 23, the formation of the extension 25a that extends the back plate 25 of the impeller, the formation of the through hole 26 in the extension 25a, In addition, since it is necessary to install the droplet collector 27, the manufacturing cost is considerably increased.

Japanese Utility Model Publication 2-74501

  Accordingly, an object of the present invention is to easily remove the drain condensed from the gas in a radial turbine in which the gas flowing in the radial direction flows into the impeller to which the moving blade is attached via the casing suction port. A radial turbine capable of improving turbine efficiency without increasing the manufacturing cost is provided.

  In order to achieve the above object, the means adopted by the radial turbine according to claim 1 of the present invention is a radial turbine that obtains a rotational force by causing a gas flowing inward in the radial direction to flow out in the direction of the rotation axis. A turbine casing, a casing suction port formed in the turbine casing, a gas flow path formed in the turbine casing and configured to flow the gas sucked from the casing suction port radially inward from the outer periphery of the turbine nozzle; And an impeller having a plurality of moving blades on which gas flowing from the outer periphery of the turbine nozzle acts.

  And the means adopted by this radial turbine is that the center line of the casing suction port is at an angle of less than 90 degrees with respect to the downward perpendicular passing through the axis of the rotation shaft of the impeller, and the diagonally downward direction. Is arranged in the direct downward direction.

  The means adopted by the radial turbine of the compressor according to claim 2 of the present invention is the radial turbine according to claim 1, wherein the gas flow path includes a casing flow path formed on an outer periphery of the impeller, The casing passage is formed by a nozzle passage communicating with the turbine nozzle, and the casing suction port is connected so that a lowermost portion of the casing passage is located inside the casing suction port. Is.

  The means adopted by the radial turbine of the compressor according to claim 3 of the present invention is the radial turbine according to claim 1 or 2, wherein the center line of the casing suction port is directed downward through the axis of the rotary shaft. It is characterized by being arranged obliquely downward or directly downward at an angle of 45 degrees or less with respect to the perpendicular.

  The radial turbine according to claim 1 of the present invention is a radial turbine that obtains a rotational force by letting a gas flowing inward in the radial direction flow out in the direction of the rotation axis, and is formed in the turbine casing and the turbine casing. The casing suction port, the gas flow passage formed in the turbine casing and allowing the gas sucked from the casing suction port to flow radially inward from the outer periphery of the turbine nozzle, and the gas flowing from the outer periphery of the turbine nozzle act. And an impeller having a plurality of moving blades.

  At the same time, according to this radial turbine, the center line of the casing suction port forms an angle of less than 90 degrees with respect to the downward perpendicular passing through the axis of the rotating shaft of the impeller, and is obliquely downward or directly below. Since it is arranged in the direction, there is no need to provide a drain discharge passage or drain collecting means in the turbine case, and the turbine efficiency can be improved without increasing the manufacturing cost.

  Moreover, according to the radial turbine which concerns on Claim 2 of this invention, the said gas flow path is the casing flow path formed in the outer periphery of the said impeller, and the nozzle channel | path which connects this casing flow path and the said turbine nozzle. The casing suction port is formed and connected so that the lowermost part of the casing flow path is located inside the casing suction port, so that drain accumulation in the turbine casing can be effectively eliminated. it can.

  Furthermore, according to the radial turbine according to claim 3 of the present invention, the center line of the casing suction port is inclined obliquely at an angle of 45 degrees or less with respect to the downward perpendicular passing through the axis of the rotating shaft. Since it is arranged in the direction or directly below, the drain in the turbine casing can be discharged more reliably by its own weight from the casing suction port.

It is a plane sectional view showing the whole radial turbine composition concerning an embodiment of the invention. It is a longitudinal cross-sectional view which shows the principal part of FIG. 1 by arrow AA. FIG. 3 is a left side view of FIG. 2. It is a longitudinal cross-sectional view which shows arrow BB of FIG. It is a longitudinal cross-sectional view which shows the principal part of the radial turbine which concerns on a prior art example.

  A radial turbine according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a plan sectional view showing the overall configuration of a radial turbine according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing the main part of FIG. FIG. 4 and FIG. 4 are longitudinal sectional views showing an arrow BB in FIG.

  The radial turbine according to the embodiment of the present invention is a radial turbine 1 that converts a gas that flows inward in the radial direction outflows in the direction of the rotation shaft 7a and converts the thermal energy of the gas into the rotation energy of the rotation shaft 7a.

  And this radial turbine 1 has the substantially circular external shape as shown in FIG. 3, the turbine casing 2 which accommodated the principal parts, such as the impeller 7, etc., and the casing inlet formed in this turbine casing 2 3. At the same time, as shown in FIG. 2, the radial turbine 1 is formed in the turbine casing 2, and the gas flow path 4 that causes the gas sucked from the casing suction port 3 to flow inward in the radial direction from the outer periphery of the turbine nozzle 5; And an impeller 7 having a plurality of moving blades 6 on which gas flowing in from the outer periphery of the turbine nozzle 5 acts.

  Here, the gas flow path 4 is formed in a substantially annular shape as shown in FIG. 4 in order to uniformly guide the gas sucked into the turbine casing 2 from the casing suction port 3 to the outer periphery of the impeller 7. 4a and a nozzle passage 4b formed in communication with the axial center CA in order to introduce the gas guided to the casing flow path 4a into the turbine nozzle 5.

  Moreover, partitions 2a and 2b for dividing the gas sucked from the casing suction port 3 into two hands along the flow path are formed in the casing flow path 4a. The nozzle passage 4b and the turbine nozzle 5 increase the speed of the gas divided and introduced into the casing flow path 4a and apply the swirling energy to the gas (and thus to the impeller 7), so that the direction from the axis CA direction to the radial direction. It is formed to change.

  In the vicinity of the axis CA in the turbine casing 2, an impeller 7 to which a plurality of moving blades 6 are attached and the impeller for converting the swirling energy of the accelerated gas into the rotational energy of the impeller 7. The rotating shaft 7a which supports 7 so that rotation is possible is accommodated.

  An impeller channel 7b is formed between each of the plurality of moving blades 6, and after colliding with the moving blades 6, the outlet 8 for discharging the gas passing through the impeller channel 7b and moving in the direction of the axis CA. Is formed in the turbine casing 2. A discharge pipe 9 is attached to the discharge port 8. On the other hand, the energy received by the moving blade 6 can be converted into the rotational energy of the rotary shaft 7 a via the impeller 7.

  A reduction gear 11 is attached to the radial turbine 1, and the rotary shaft 7 a of the radial turbine 1 and the high speed shaft 12 of the reduction gear 11 are directly connected. And the high speed rotation speed in the rotating shaft 7a based on the rotational energy obtained by the radial turbine 1 is changed from the high speed shaft gear 12a attached to the high speed shaft 12 to the low speed shaft gear 13a attached to the low speed shaft 13. The speed is reduced to a low speed at the low speed shaft 13.

  In the radial turbine 1 according to the embodiment of the present invention configured as described above, a suction opening surface 3a is provided at the tip of the casing suction port 3 as shown in FIGS. The center line CL of the casing suction port 3 is disposed obliquely downward or directly downward with an angle θ of less than 90 degrees with respect to the downward perpendicular VL passing through the axis CA of the rotating shaft. The drain condensed from the gas in the turbine casing 2 is formed so as to be discharged from the casing suction port 3 by its own weight.

  The casing suction port 3 is disposed with its center line CL directed obliquely upward or directly upward at an angle θ of 90 degrees or more with respect to a downward vertical line VL passing through the axis CA of the rotating shaft 7a. This is because it becomes difficult for the drain in the turbine casing 2 to be discharged from the casing suction port 3 by its own weight.

  An air supply pipe (not shown) for supplying this gas is connected to the suction opening surface 3 a of the casing suction port 3. If drain stays in this air supply pipe, it may cause corrosion of the pipe. Connect a drain discharge pipe (not shown) with an open / close valve (not shown) to the air supply pipe. It is preferable that the valve can be opened every predetermined time so that the drain can be collected.

  In addition, in order to allow the drain in the turbine casing 2 to be discharged from the casing suction port 3 with its own weight more reliably, the casing suction port 3 has its center line CL downwardly passing through the axis CA of the rotating shaft. It is arranged in an obliquely downward direction or a direct downward direction with an angle θ of 45 degrees or less with respect to the vertical line VL, so that the drain condensed from the gas in the turbine casing 2 can be reliably obtained by its own weight from the casing suction port 3. It is further preferable in that it can be discharged.

  In order to form the casing suction port 3 having the above-described configuration, when the turbine casing 2 is formed by casting or the like, the center line CL of the casing suction port 3a from the beginning is set to the axis CA of the rotary shaft 7a. What is necessary is just to form in the diagonally downward direction or the direct downward direction, forming the angle (theta) below 90 degree | times with respect to the downward perpendicular line VL which passes, and also the angle (theta) below 45 degree | times.

  Further, as shown in FIG. 2, the casing suction port 3 is connected so that the lowermost part 4c of the casing channel is located inside the suction channel 3b formed in the casing suction port 3. It is preferable in that drain accumulation in the turbine casing 2 can be effectively eliminated.

  When the angle θ formed between the center line CL of the casing suction port 3 and the downward vertical line VL passing through the axis CA is close to 90 degrees, along the center line CL at the bottom of the cross section of the suction flow path 3b. It is preferable to form a groove, such as a V-shaped groove or a U-shaped groove, so that the drain can be easily removed out of the turbine casing 2 along the groove.

  On the other hand, the angle θ between the center line CL of the casing suction port 3 and the downward vertical line VL passing through the axis CA is more than 90 degrees, and the angle θ is 45 degrees or less and obliquely downward or directly downward. In the same manner as described above, a groove may be formed along the center line CL at the lowest part of the cross section of the suction flow path 3b.

  Moreover, it is preferable that the suction flow path 3b of the casing suction port 3 has a cross-sectional area at least twice as large as the maximum flow path cross section of the casing flow path 4a in the flow path cross section where the partition 2a does not exist. When the gas suction flow velocity in the suction flow passage 3b is faster than the flow velocity in the casing flow passage 4a, the drain discharged from the turbine casing 2 to the suction flow passage 3b is sucked by the frictional resistance of the suction gas sucked in the opposite direction. This is because further discharge in the direction of the opening surface 3a may be prevented.

  Furthermore, the cross-sectional shape of the suction flow passage 3b is not particularly limited, such as a circular cross-section, an elliptical cross-section, or a polygonal cross-section, but it is preferably a circular cross-section from the viewpoint of ease of manufacture.

  Next, the operation of the radial turbine 1 according to the embodiment of the present invention configured as described above will be described along the flow of gas.

  As shown in FIGS. 3 and 4, the gas serving as the working medium of the radial turbine 1 forms an angle θ with the center line CL being less than 90 degrees with respect to the downward vertical line VL passing through the axis CA of the rotating shaft 7 a. The air is sucked into the turbine casing 2 through an air supply pipe (not shown) from the suction opening surface 3a of the casing suction port 3 arranged obliquely downward or directly downward.

  The gas sucked from the suction opening surface 3a is introduced into the suction flow path 3b of the casing suction port 3 as shown by the arrows in FIGS. To the casing flow path 4a. Next, as shown in FIG. 2, the gas that has flowed into the turbine nozzle 5 inward in the radial direction from the nozzle passage 4 b in the axial center CA direction is accelerated by the turbine nozzle 5 as a swirl flow around the axial center CA. Collides with the moving blade 6. And the gas which collided with the moving blade 6 flows into the impeller channel 7b formed between these moving blades 6.

  At that time, the gas colliding with the moving blade 6 gives torque to the rotating shaft 7a connected to the impeller 7 as it goes from the outer peripheral side to the inner peripheral side in the impeller 7, and then decreases the rotational speed. However, it flows out in the direction of the axis CA and is discharged from the discharge pipe 9 attached to the turbine casing 2 through the discharge port 8.

  Then, the rotation of the rotating shaft 7 a is transmitted to the rotation of the high speed shaft 12 of the speed reducer 11. The high speed shaft 12 rotates at a low speed as needed in the low speed shaft 13 from the high speed shaft gear 12a attached to the high speed shaft 12 to the low speed shaft gear 13a attached to the low speed shaft 13. Decelerated to a number.

  According to the radial turbine 1 according to the embodiment of the present invention configured as described above, the center line CL of the casing suction port 3 is directed to the downward vertical line VL passing through the axis CA of the rotating shaft 7a of the impeller 7. The casing suction port 3 is arranged in an obliquely downward direction or a direct downward direction with an angle θ of less than 90 degrees, and the shape of the casing suction port 3 is such that drain condensed from the gas can be discharged from the casing suction port 3 by its own weight. Is formed.

  As a result, there is no need to provide a drain discharge passage or drain collector in the turbine casing 2 and the retention of drain in the gas flow path 4 in the turbine casing 2 is eliminated, thereby increasing the manufacturing cost. The turbine efficiency can be improved without any problem.

CA: axial center (of rotating shaft) CL: center line of casing suction port VL: downward vertical line passing through axis CL CL: angle formed by downward vertical line VL passing through center line CL of casing suction port 1 : Radial turbine 2: Turbine casing 2a, 2b: Partition 3: Casing suction port 3a: Suction opening surface 3b: Suction channel 4: Gas channel 4a: Casing channel 4b: Nozzle channel 4c: Bottom of casing channel 5: Turbine nozzle 6: Moving blade 7: Impeller 7a: Rotating shaft 7b: Impeller flow path 8: Discharge port 9: Discharge pipe 11: Reducer 12: High speed shaft 12a: High speed shaft gear 13: Low speed shaft 13a: Low speed shaft gear

Claims (3)

A radial turbine that obtains a rotational force by causing a gas flowing inward in a radial direction to flow out in a rotational axis direction,
A turbine casing;
A casing suction port formed in the turbine casing;
A gas flow path that is formed in the turbine casing and allows the gas sucked from the casing suction port to flow radially inward from the outer periphery of the turbine nozzle;
An impeller having a plurality of moving blades on which gas flowing from the outer periphery of the turbine nozzle acts;
A center line of the casing suction port is disposed in an obliquely downward direction or a direct downward direction at an angle of less than 90 degrees with respect to a downward perpendicular passing through the axis of the rotation shaft of the impeller. A characteristic radial turbine. The gas flow path is formed by a casing flow path formed on the outer periphery of the impeller, and a nozzle passage communicating the casing flow path and the turbine nozzle,
The radial turbine according to claim 1, wherein the casing suction port is connected so that a lowermost portion of the casing flow path is located inside the casing suction port.   A center line of the casing suction port is disposed obliquely downward or directly downward at an angle of 45 degrees or less with respect to a downward perpendicular passing through the axis of the rotating shaft. The radial turbine according to claim 1 or 2.