JP2015059525A - Exhaust turbine supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain an appropriate clearance between a turbine blade and a shroud ring by considering the mounting structure and shape of the shroud ring in an exhaust turbine supercharger.SOLUTION: An axial flow type exhaust turbine supercharger includes: a gas inlet casing that defines an exhaust gas flow passage; a gas outlet casing 6 communicated with the gas inlet casing via an exhaust gas outlet guide cylinder 5; and a turbine moving blade 7 and a turbine nozzle 8 disposed adjacent to the turbine moving blade, which are located on the upstream side of the exhaust gas outlet guide cylinder. Expansion of exhaust gas introduced to the turbine moving blade through the turbine nozzle causes rotation of the turbine moving blade, and by using axial rotating force obtained by the rotation of the turbine moving blade, a compressor is rotated. A shroud ring 20 that surrounds the turbine moving blade and defines a clearance g with a tip of the turbine moving blade is arranged on the upstream side of the exhaust gas outlet guide cylinder. One peripheral edge side of the shroud ring is fixed to the upstream side of the exhaust gas outlet guide cylinder, and the other peripheral edge side is engaged with the turbine nozzle side so as to enable expansion of the diameter in the radial direction.

Description

  The present invention relates to an exhaust turbine supercharger used in combination with a large internal combustion engine such as a marine internal combustion engine or a power generation internal combustion engine, and more particularly to an exhaust turbine turbocharger that supercharges an internal combustion engine using an axial flow turbine. Regarding the feeder.

Conventionally, various types of superchargers have been used to improve the output of an internal combustion engine. For example, an exhaust turbine supercharger using an axial turbine is employed in a large diesel engine or the like that requires high output, such as a ship or a power generation device. This is because the engine itself is large and the amount of intake air is very large, so the exhaust turbine supercharger must be large and have a large capacity, and can be manufactured easily and inexpensively compared to a radial turbine. This is because an axial turbine can be considered.
An exhaust turbine supercharger generally includes a single stage exhaust gas turbine and a compressor mounted on the same rotating shaft, and rotates the exhaust gas turbine by exhaust gas, and drives the compressor with the rotational force. It is a thing of composition to do.

As a conventional exhaust turbine supercharger employing an axial flow turbine, there is one disclosed by the present applicant as shown in Patent Document 1.
In this case, Patent Document 1 proposes a technique for solving the problem of thermal expansion and the problem of weight increase by the assembly structure of the casing. That is, in Patent Document 1, a gas inlet having a double structure in which a separate inner casing and outer casing are integrated by bolting and a space formed between the two casings serves as an exhaust gas flow path that guides exhaust gas to the turbine nozzle. A casing is provided, exhaust gas passages are provided over the entire circumference in the turbine rotation direction, and the inner casing is detachable in the axial direction.
In Patent Document 1, supercharged exhaust gas is led from a gas inlet casing, a turbine nozzle, and a turbine rotor blade to a gas outlet casing, and discharged from the gas outlet to the outside.

  By the way, in the exhaust turbine supercharger using the axial turbine described above, there is no large temperature difference between the inner and outer casings, and the heat spread in the radial direction is uniform, so an inlay structure between the turbine nozzle and the gas guide cylinder is possible. Thus, the sealing performance of the fitting portion is improved and gas leakage can be prevented.

  Moreover, in patent document 2, the clearance gap between the front-end | tip and shroud ring of the turbine rotor blade of the gas turbine used in a high temperature area is effectively sealed, and it is supposed that turbine efficiency can be improved.

JP 2006-153002 A JP-A-10-220204

However, in Patent Document 1, there is a turbine blade tip clearance (clearance) between the turbine rotor blade tip and the gas guide cylinder, and the turbine rotor blade is subjected to centrifugal and thermal expansion during supercharger operation. The turbine blade tip clearance between the gas outlet guide cylinder and the gas outlet guide cylinder that extends in the radial direction may be reduced and contact may occur.
Further, in Patent Document 2, in order to suppress the gap between the turbine blade tip and the shroud ring as much as possible, a dug groove that allows the tip of the turbine blade to partially face the portion facing the turbine blade tip on the shroud ring side. And a ceramic fiber is provided in the groove. In this way, special processing is required for the shroud ring, which is complicated, and wears out easily, and the frequency of replacement of the shroud ring is higher than other parts.
The present invention has been proposed from the background as described above, and adopts a shroud ring mounting structure, material, and shape taking thermal expansion into account, and ensures an appropriate clearance between the turbine blade and the shroud ring. It is an object of the present invention to provide an exhaust turbine supercharger in which there is no problem such as contact between a turbine blade tip and a shroud ring.

  In order to solve the above-mentioned problems, in the present invention according to claim 1, the gas inlet casing defining the exhaust gas flow path through which the introduced exhaust gas flows, the gas inlet casing, and the exhaust gas outlet guide tube are provided. The turbine rotor blade is provided with a gas outlet casing that communicates with the turbine rotor blade and a turbine nozzle disposed adjacent to the turbine rotor blade on the upstream side of the exhaust gas outlet guide cylinder, and is expanded by exhaust gas introduced into the turbine rotor blade through the turbine nozzle. In the axial flow type exhaust turbine supercharger in which the compressor is rotated by the shaft rotational force obtained by rotating the turbine blade, the turbine rotor blade is surrounded on the upstream side of the exhaust gas outlet guide cylinder, A shroud ring is provided to regulate the gap between the two, and the shroud ring can be fixed to the upstream side of the exhaust gas outlet guide cylinder while the other peripheral side can be radially expanded in the radial direction. It engaged comprising a turbine nozzle side, and wherein the.

As a result, the shroud ring is thin during operation and has a good temperature responsiveness, so that it expands by a certain amount in the radial and axial directions due to thermal expansion.
During operation, even if the turbine blades extend, they extend in the radial and axial directions of the shroud ring that surrounds the outer periphery of the turbine blades, so that the clearance between the turbine blades and the shroud ring is adequately secured and cannot be contacted. Absent.

  In the present invention described in claim 2, the shroud ring is characterized in that one peripheral edge side is fixed to the upstream side of the exhaust gas outlet guide tube with a fastening member via a flange portion.

  As a result, the shroud ring is fixed only at one peripheral edge side via the flange portion, so that the shroud ring expands in the radial direction along with the expansion of the exhaust gas outlet guide cylinder by operation, and a clearance with the turbine blade is secured. can do.

  Furthermore, the present invention according to claim 3 is characterized in that the shroud ring is formed of a thin steel material having a thermal expansion coefficient equivalent to that of the turbine rotor blade.

  As a result, the thermal response of the shroud ring is good, and even if the turbine blades expand in the radial and axial directions during operation, the shroud ring outside the turbine blades extends in the radial direction equally. Wings and shroud rings do not interfere.

According to the present invention, the shroud ring is thin during operation and has a good temperature responsiveness, so that it expands by a certain amount in the radial and axial directions due to thermal expansion.
During operation, even if the turbine blade extends, the radial and axial expansion of the shroud ring that surrounds the outer periphery of the turbine blade ensures that the clearance between the turbine blade and the shroud ring is properly secured and that Absent.

It is sectional drawing by the side of the turbine of the exhaust turbine supercharger concerning this invention. It is the figure which expanded and showed the turbine nozzle and turbine rotor blade which are the principal parts A of the exhaust turbine supercharger shown in FIG. FIG. 3 is a schematic diagram for explaining a radial change due to thermal expansion exerted on the turbine rotor blade and the shroud ring during operation in the turbine nozzle and the turbine rotor blade of FIG. 2. FIG. 3 is a schematic diagram for explaining a change in the radial direction of the shroud ring when the turbine nozzle and the turbine blade of FIG. 2 are in contact with the shroud ring due to thermal expansion of the turbine blade during operation.

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

FIG. 1 shows an embodiment of an exhaust turbine supercharger 1 for a large internal combustion engine in which a turbine and a compressor are provided coaxially.
This exhaust turbine supercharger 1 rotates a coaxial compressor 3 with an axial output obtained by expanding exhaust gas of an internal combustion engine introduced into an axial flow turbine 2, and compressed air compressed to a high pressure by the compressor 3. Is an axial flow type configured to supply to the internal combustion engine.

  That is, the exhaust turbine supercharger 1 includes a gas inlet casing 4 that defines an exhaust gas passage (described later) through which the introduced exhaust gas flows, and the gas inlet casing 4 and the exhaust gas outlet guide cylinder 5. A gas outlet casing 6 that communicates with each other, a turbine rotor blade 7 on the upstream side of the exhaust gas outlet guide cylinder 5, and a turbine nozzle 8 that is disposed adjacent to the turbine rotor blade 7, are introduced into the turbine rotor blade 7 through the turbine nozzle 8. This is an axial flow type in which the compressor 3 is rotated by an axial rotational force obtained by rotating the turbine rotor blade 7 by the expansion of the exhaust gas.

The gas inlet casing 4 is configured by integrating an inner casing 4a and an outer casing 4b with a fastening member, and an exhaust gas passage 9 for guiding exhaust gas to the turbine nozzle 8 between the inner casing 4a and the outer casing 4b. Is defined. In this case, the exhaust gas passage 9 is formed over the entire circumference in the rotational direction of the axial turbine 2, and the exhaust gas introduced from the gas inlet 4 i of the gas inlet casing 4 passes through the exhaust gas passage 9 to the gas outlet. 4o, the gas is discharged from the outlet of the gas outlet casing 6 to the outside through the exhaust gas outlet guide tube 5.
The gas outlet 4o is provided to be open so as to supply exhaust gas to the turbine nozzle 8 over the entire circumference in the rotational direction.

Further, the axial turbine 2 is configured such that a large number of turbine rotor blades 7 are attached to a rotor disk 11 provided at one end of the rotor shaft 10 in the circumferential direction. For the turbine rotor blade 7 and the rotor disk 11, for example, heat-resistant steel such as SUH (Steel Use Heat Resisting) or Nimonic (Ni—Cr alloy) can be used.
The turbine blade 7 is provided adjacent to the downstream side serving as the outlet of the turbine nozzle 8, that is, adjacent to the upstream side of the exhaust gas outlet guide cylinder 5 in the gas outlet casing 6, and high-temperature exhaust gas ejected from the turbine nozzle 8 is turbine-driven. The rotor disk 11 and the rotor shaft 10 are rotated by expanding through the blades 7.

Further, on the gas outlet 4 o in the gas inlet casing 4, that is, on the side facing the upstream side of the exhaust gas outlet guide cylinder 5 in the gas outlet casing 6, an inner peripheral portion of a ring-shaped member (nozzle ring) forming the turbine nozzle 8. 8a is fixed on the shaft. That is, the turbine nozzle 8 here is a ring-shaped member and has a double ring structure in which the ring members of the inner peripheral portion 8a and the outer peripheral portion 8b having a predetermined interval are connected by a partition member.
On the other hand, as shown in FIG. 2, the outer peripheral portion 8b of the nozzle ring forming the turbine nozzle 8 has an end inner peripheral surface 8c on the gas inlet side (gas outlet 4o side) expanded. Further, the end portion on the rotor disk side of the outer casing 4b is provided with a stepped portion 4bb so that the inner peripheral surface thereof is bent in the rotor axial direction, and the outer peripheral surface of the stepped portion 4bb and the gas inlet side end portion of the nozzle ring. A step portion 8d provided in the shaft is engaged in the axial direction.

  The outer peripheral portion 8b of the turbine nozzle 8 is attached to the upstream side of the exhaust gas outlet guide tube 5 at the end portion on the gas outlet side (turbine rotor blade 7 side), as will be described in detail later. The shroud ring 20 surrounding the two is connected in an engaged state with each other (inlay structure).

Therefore, the shroud ring 20 surrounding the turbine rotor blade 7 will be described in detail.
As described above, the shroud ring 20 surrounds the turbine rotor blade 7 on the upstream side of the exhaust gas outlet guide cylinder 5, and defines a gap g with the tip of the turbine rotor blade 7 (FIGS. 2 and 2). 3).
That is, the shroud ring 20 is an annular ring formed of a thin steel material, and one peripheral edge side is fixed to the upstream side of the exhaust gas outlet guide tube 5 with the bolt member 21 via the flange portion 20f. Further, the other peripheral edge side of the shroud ring 20 is engaged with the outer peripheral portion 8b of the turbine nozzle 8 from the radially outer side at the engagement portion with the outer peripheral portion 8b of the turbine nozzle 8, thereby causing the shroud ring 20 to have a diameter. The diameter can be expanded in the direction. That is, even if the thermal expansion of the turbine blade 7 during operation may contact the shroud ring 20, the other peripheral edge side of the shroud ring 20 is deformed radially outward, so that the turbine blade 7. And the shroud ring 20 are reduced in contact pressure, and damage to the turbine rotor blade 7 is suppressed.

Moreover, the mounting structure with respect to the exhaust gas outlet guide cylinder 5 in the above shroud ring 20 is demonstrated concretely.
That is, when the one peripheral edge side of the shroud ring 20 is fixed to the upstream side of the exhaust gas outlet guide tube 5 with the bolt member 21 via the flange portion 20f, the gasket G is against the upstream end surface of the exhaust gas outlet guide tube 5. The bolt member 21 is screwed onto the upstream end face of the exhaust gas outlet guide tube 5 in a state where the flange portion 20f is pressed through the flange. At this time, the bolt head 21h of the bolt member 21 is sandwiched with the spring washer w to increase the fastening force and the air tightness so as to minimize the leakage of the exhaust gas.

  And when this shroud ring 20 is fixed to the upstream end face of the exhaust gas outlet guide cylinder 5, the gap g with the tip of the turbine rotor blade 7 is set to be, for example, 0.3 to 0.6 mm. Yes.

Next, operation | movement and an effect | action are demonstrated about the exhaust turbine supercharger 1 demonstrated above.
When the supercharging operation is performed by introducing the exhaust gas, the exhaust gas introduced from the gas inlet 4 i of the gas inlet casing 4 is guided to the gas outlet 4 o through the exhaust gas passage 9. This exhaust gas is sucked into the turbine nozzle 8 from the gas outlet 4o that opens over the entire circumference in the rotation direction, and expands when passing through the turbine rotor blade 7 to rotate the rotor disk 11 and the rotor shaft 10. The compressor 3 is driven to compress the air supplied to the internal combustion engine. The air compressed by the compressor 3 is sucked through a filter (not shown). The exhaust gas expanded by the turbine rotor blade 7 is guided to the exhaust gas outlet guide cylinder 5 and the gas outlet casing 6 and flows out to the outside.

When the supercharging operation is continued, the exhaust gas passing through the exhaust gas passage 9 is sucked into the turbine nozzle 8 and passes through the turbine rotor blade 7. For this reason, the turbine nozzle 8, the turbine rotor blade 7, and the shroud ring 20 surrounding the turbine rotor blade 7 are heated by the exhaust gas. For this reason, the turbine rotor blade 7 and the shroud ring 20 are thermally expanded in the radial direction and the axial direction (see FIG. 3).
For example, when the temperature of the exhaust gas is 400 ° C., if the diameter of the rotor disk 11 is 900 mm, the radial extension of the turbine rotor blade 7 is 2 mm.

However, the shroud ring 20 positioned on the radially outer side of the turbine rotor blade 7 also thermally expands uniformly in the radial direction and the axial direction due to the linear expansion coefficient characteristic.
Since the shroud ring 20 is composed of a thin annular body, the temperature responsiveness is good, and the thermal expansion is performed prior to the elongation on the turbine blade 7 side, so that the turbine blade 7 and the shroud ring 20 are appropriate. A sufficient gap g is secured, and contact between the turbine rotor blade 7 and the shroud ring 20 can be avoided.
For example, even if the temperature of the exhaust gas exceeds the assumed temperature and the turbine rotor blade 7 side is greatly stretched and contacts the shroud ring 20, the other peripheral edge side of the shroud ring 20 is the turbine nozzle. 8 is engaged with the outer peripheral portion 8b of the turbine nozzle 8 from the outside in the radial direction at the site of engagement with the outer peripheral portion 8b. Therefore, the shroud ring 20 is pushed so as to escape outward in the radial direction. Problems that are damaged by contact between the moving blade 7 and the shroud ring 20 can be suppressed as much as possible (see FIG. 4).

The exhaust turbine supercharger according to the present invention has been described with reference to the embodiment.
Of course, the material, dimensions, and shape of the shroud ring 20 in the above embodiment are adopted in view of the specifications, standards, and the like of the exhaust turbine turbocharger provided.

  The shroud ring of the turbine rotor blade according to the present invention is not limited to such an exhaust turbine, but can be applied to a steam turbine, a gas turbine, and the like, and is highly versatile.

DESCRIPTION OF SYMBOLS 1 Exhaust turbine supercharger 2 Axial flow turbine 3 Compressor 4 Gas inlet casing 4a Inner casing 4b Outer casing 4ba Inner peripheral surface 4bb Stepped part 4i Gas inlet 4o Gas outlet 4c End inner peripheral part 5 Exhaust gas outlet guide cylinder 6 Gas outlet casing 7 Turbine blade 8 Turbine nozzle 8a Inner peripheral part 8b Outer peripheral part 8d Stepped part 9 Exhaust gas flow path 10 Rotor shaft 11 Rotor disk 20 Shroud ring 20f Flange part 21 Bolt member 21h Bolt head w Spring washer

Claims (3)

A gas inlet casing defining an exhaust gas passage through which exhaust gas to be introduced flows, a gas outlet casing communicating with the gas inlet casing via an exhaust gas outlet guide cylinder, and a turbine upstream of the exhaust gas outlet guide cylinder A turbine nozzle disposed adjacent to the turbine blade, and compressed by an axial rotational force obtained by rotating the turbine blade by expansion of exhaust gas introduced into the turbine blade through the turbine nozzle In the axial flow type exhaust turbine supercharger that rotates the machine,
Provided on the upstream side of the exhaust gas outlet guide cylinder is a shroud ring that surrounds the turbine rotor blade and defines a gap with the turbine rotor blade tip,
The shroud ring is configured such that one peripheral edge side is fixed to the upstream side of the exhaust gas outlet guide cylinder, and the other peripheral edge side is engaged with the turbine nozzle side so as to be radially expandable. Exhaust turbine supercharger.   2. The exhaust turbine supercharger according to claim 1, wherein the shroud ring is fixed to the upstream side of the exhaust gas outlet guide cylinder by a fastening member on the one peripheral edge side through a flange portion. The exhaust turbine supercharger according to claim 1 or 2, wherein the shroud ring is formed of a thin steel material having a thermal expansion coefficient equivalent to that of the turbine rotor blade.

Images