Steam turbine inlet structure

Abstract

The present invention relates to the technical field of steam turbines, and in particular to a steam inlet structure of a steam turbine, wherein a steam inlet chamber is formed in an inner cylinder, steam inlets are correspondingly provided on the upper half of the outer cylinder and the upper half of the inner cylinder, a steam inlet plug is provided at the steam inlet, the steam inlet plug is inserted into the upper half of the outer cylinder and connected to the upper half of the inner cylinder and communicated with the steam inlet chamber, and the steam inlet chamber is a tapered cross-section volute type. In the steam inlet structure of the steam turbine of the present invention, the steam inlet chamber is a tapered cross-section volute type, which can be suitable for single-side tangential full-circle steam inlet, and can effectively reduce the total pressure loss of the cylinder steam inlet chamber, thereby improving the flow efficiency of the unit.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbines, and in particular to a steam inlet structure of a steam turbine. Background Art

[0002] The steam inlet chamber of the steam turbine is the steam flow passage connecting the valve and the flow blade stage group. The rationality of the steam inlet chamber design is crucial to the efficiency and safety of the unit. Most of the chambers that domestic and foreign companies use full-circle steam inlet adopt the lower half steam inlet equal section design. In the single-sided equal-section steam inlet chamber, the flow field in the chamber is unevenly distributed, the outlet steam flow angle is large and the circumferential difference is obvious, resulting in a large first-stage stator blade attack angle and poor aerodynamic performance. For the cylinders with steam inlet on both sides, the steam inlets are arranged symmetrically on the left and right. After the steam enters the inner cylinder, there will be a collision and form a vortex, which will make the steam flow field in the steam inlet chamber disordered, which will also cause a large capacity loss and affect the efficiency of the unit. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-efficiency steam turbine steam inlet structure to overcome the above-mentioned defects of the prior art.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: a steam turbine steam inlet structure, comprising an outer cylinder and an inner cylinder arranged inside the outer cylinder, a steam inlet chamber is formed in the inner cylinder, steam inlets are correspondingly opened on the outer cylinder and the inner cylinder, a steam inlet plug is provided at the steam inlet, the steam inlet plug is inserted into the outer cylinder and connected to the inner cylinder and communicated with the steam inlet chamber, and the steam inlet chamber is a volute type with a tapered cross-section.

[0005] Preferably, the steam inlet chamber is a tapered cross-section volute type designed using a constant speed moment calculation method, a constant velocity calculation method, a variable speed calculation method, or a variable speed moment calculation method.

[0006] Preferably, one end of the steam inlet pipe inserted into the outer cylinder is detachably connected to the inner cylinder, the other end of the steam inlet pipe is detachably connected to the steam inlet valve, and a gasket is provided between the steam inlet pipe and the steam inlet valve.

[0007] Preferably, a first annular connector is circumferentially provided at one end of the steam inlet pipe inserted into the outer cylinder, a first annular connector groove is provided on the end face of the inner cylinder at the steam inlet, and the first annular connector is inserted into the first annular connector groove.

[0008] Preferably, a self-balancing component for offsetting the unbalanced force in the steam inlet chamber is provided on the inner cylinder, and the self-balancing component is arranged on the opposite side of the steam inlet.

[0009] Preferably, self-balancing interfaces are correspondingly provided on the outer cylinder and the inner cylinder, and the self-balancing interfaces are located on the opposite side of the steam inlet. The self-balancing assembly includes a self-balancing plug provided at the self-balancing interface, one end of the self-balancing plug is closed and the other end is open, and the open end of the self-balancing plug is inserted into the outer cylinder, connected to the inner cylinder and communicated with the steam inlet chamber.

[0010] Preferably, one end of the self-balancing cannula inserted into the outer cylinder is detachably connected to the inner cylinder, and the other end of the self-balancing cannula is connected to the outer cylinder.

[0011] Preferably, a second annular connector is circumferentially provided at one end of the self-balancing cannula inserted into the outer cylinder, a second annular connector groove is provided on the end face of the inner cylinder at the self-balancing interface, and the second annular connector is inserted into the second annular connector groove.

[0012] Preferably, the outer cylinder includes an outer cylinder upper half and an outer cylinder lower half connected at a horizontal center plane, and the inner cylinder includes an inner cylinder upper half and an inner cylinder lower half connected at a horizontal center plane; steam inlets are correspondingly opened on the outer cylinder upper half and the inner cylinder upper half, or steam inlets are correspondingly opened on the outer cylinder lower half and the inner cylinder lower half.

[0013] Preferably, the first-stage stationary vanes in the inner cylinder adopt large steam inlet angle stationary vanes that match the steam outlet angle of the steam inlet chamber.

[0014] Compared with the prior art, the present invention has significant improvements:

[0015] In the steam turbine steam inlet structure of the present invention, the steam inlet chamber is a tapered cross-section volute type, which can be suitable for single-side tangential full-circle steam inlet and can effectively reduce the total pressure loss of the cylinder steam inlet chamber, thereby improving the flow efficiency of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a cross-sectional schematic diagram of the steam inlet structure of the steam turbine according to the first embodiment of the present invention.

[0017] Figure 2 It is a schematic diagram of the fluid domain in the steam inlet chamber of the steam turbine steam inlet structure according to the first embodiment of the present invention.

[0018] Figure 3 It is a structural schematic diagram of the first-stage stationary blades in the steam inlet structure of the steam turbine according to the first embodiment of the present invention.

[0019] Figure 4 It is a cross-sectional schematic diagram of the steam inlet structure of the steam turbine according to the second embodiment of the present invention.

[0020] Figure 5 It is a schematic diagram of the fluid domain in the steam inlet chamber of the steam turbine steam inlet structure according to the second embodiment of the present invention.

[0021] The reference numerals are described as follows:

[0022] 11. Upper half of outer cylinder 12. Lower half of outer cylinder

[0023] 13. First groove 14. Anti-rotation pin

[0024] 20. Steam inlet chamber 21. Upper half of inner cylinder

[0025] 22. Lower half of the inner cylinder 23. Cat's claw

[0026] 24. Second groove 25. First annular plug-in groove

[0027] 26. Second annular plug groove 3. Steam inlet plug pipe

[0028] 31. First annular connector 4. Steam inlet valve

[0029] 5. Gasket 6. Self-balancing cannula

[0030] 61. Second annular connector 7. First stage stationary blade

[0031] 8. Inner cylinder bolts 9. Outer cylinder bolts DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0036] Embodiment 1

[0037] like Figures 1 to 3 FIG. 1 shows a first embodiment of a steam turbine steam inlet structure according to the present invention.

[0038] See also Figure 1 The steam inlet structure of the steam turbine of the first embodiment is a horizontal center-divided cylinder, which includes an outer cylinder and an inner cylinder arranged inside the outer cylinder. The outer cylinder includes an outer cylinder upper half 11 and an outer cylinder lower half 12 connected at the horizontal center-divided plane, and the inner cylinder includes an inner cylinder upper half 21 and an inner cylinder lower half 22 connected at the horizontal center-divided plane. A steam inlet chamber 20 is formed in the inner cylinder. The first embodiment adopts upper-half steam inlet, and steam inlets are correspondingly provided on the outer cylinder upper half 11 and the inner cylinder upper half 21. A steam inlet plug 3 is provided at the steam inlet. The steam inlet plug 3 is inserted into the outer cylinder upper half 11 at the steam inlet and connected to the inner cylinder upper half 21, and the steam inlet plug 3 is communicated with the steam inlet chamber 20 for conveying steam into the steam inlet chamber 20. The steam inlet chamber 20 in the first embodiment is a tapered section volute type designed by a constant speed moment calculation method or a constant velocity calculation method or a variable speed calculation method or a variable velocity moment calculation method.

[0039] Specifically, in the first embodiment, the steam inlet chamber 20 can be a tapered cross-section volute type designed using the constant velocity moment calculation method. Under ideal conditions, the movement of the steam flow in the steam inlet volute forms a certain amount of circulation in the volute, and flows out evenly along the circumferential outlet and enters the downstream stator flow channel. Therefore, the flow of steam in the volute can be simplified to a plane potential flow, and further abstracted to an ideal fluid axisymmetric potential flow, whose streamlines are equiangular helices. In order to reduce flow losses, the introduction of the fluid should conform to the shape of an equiangular helix, which is a free vortex design. The constant velocity moment calculation method used in the steam inlet chamber 20 of the first embodiment is a design method based on the free vortex concept.

[0040] Specifically, in the polar coordinate system, the velocity potential function of the axisymmetric potential flow of an ideal fluid is:

[0041]

[0042] The stream function is:

[0043]

[0044] The equation of the equipotential line can be obtained through the velocity potential function:

[0045]

[0046] The streamline equation can be obtained through the stream function:

[0047]

[0048] In the above formula, Γ is the vortex strength and Q is the flow rate.

[0049] It can be seen that the streamline equation is an equiangular spiral equation, that is, the streamline is an equiangular spiral. Therefore, according to the vortex strength and flow value required by the steam turbine with different working parameters, the above streamline equation can be substituted to calculate and design the constant velocity moment tapered cross-section volute with different external dimensions. Through numerical simulation evaluation, the optimal volute profile and the corresponding steam outlet angle can be obtained.

[0050] Figure 2 The schematic diagram of the fluid domain in the steam inlet chamber 20 of the uniform moment tapered cross-section single-side tangential steam inlet volute of the first embodiment is shown. In practical applications, by comparing the uniform cross-section single-side tangential steam inlet volute, the steam inlet structure of the first embodiment is adopted, and the total pressure loss of the steam inlet chamber is reduced from 0.7575% to 0.1045%. The average steam outlet angle of the uniform cross-section volute is calculated to be 168°, while the average steam outlet angle of the tapered cross-section volute of the first embodiment is 152°. Therefore, the total pressure loss of the steam inlet chamber plus the first-stage stationary blade is reduced from 2.0807% to 0.2334%, and the flow efficiency of the unit is greatly improved.

[0051] See also Figure 3 In order to ensure the efficiency of the first-stage stationary blades 7, preferably, the first-stage stationary blades 7 in the inner cylinder adopt large steam inlet angle stationary blades that match the steam outlet angle of the steam inlet chamber 20. Large steam inlet angle stationary blades refer to stationary blades whose steam inlet angle is greater than that of conventional stationary blades. In a preferred embodiment, compared with conventional stationary blades, the steam inlet angle of the first-stage stationary blades 7 is increased from 90° to 140°, and the safety and reliability of the first-stage stationary blades 7 can be ensured by strength calculation and analysis.

[0052] In the second embodiment, the steam inlet chamber 20 may be a tapered volute type designed using a constant velocity calculation method. The constant velocity calculation method assumes that the fluid velocity in the volute is V u =const regular distribution (where V u is the flow velocity of each section of the volute, and const is a constant). Its characteristic is that the flow velocity of each section of the volute is equal. Therefore, the flow velocity at the tail of the volute is compared with V. u R = const calculated to be smaller (where V u R is the velocity moment), which makes the volute section wider and the loss smaller.

[0053] In the third embodiment, the steam inlet chamber 20 may be a tapered volute type designed using a variable speed calculation method. The variable speed calculation method assumes that the flow velocity V of each section of the volute is u It gradually decreases along the circumference. For example, the flow velocity at the volute inlet section is V u , and the velocity of the tail section of the volute is (0.6-0.8)V uThe flow velocity of each middle section is distributed according to the law of straight line or parabola, which further reduces the flow velocity at the tail of the volute and reduces the loss at the tail.

[0054] In the fourth embodiment, the steam inlet chamber 20 may be a tapered volute designed using a variable speed moment calculation method. The variable speed moment calculation method assumes that the speed moment is unevenly distributed along the axial direction and satisfies a functional relationship with the circumferential angle: V u R = k(φ), where V u R is the velocity moment, and φ is the circumferential position of the volute section. This method can not only ensure the uniform distribution of pressure and flow velocity at the tail of the volute, but also reduce pressure loss and improve efficiency.

[0055] In summary, the tapered cross-section volute-type steam inlet chamber 20 of the first embodiment is suitable for single-side tangential full-circle steam inlet and can effectively reduce the total pressure loss of the cylinder steam inlet chamber, thereby improving the flow efficiency of the unit.

[0056] See also Figure 1 In the first embodiment, the lower half 22 of the inner cylinder has a cat claw 23 extending at the horizontal mid-plane, and the lower half 12 of the outer cylinder has a first groove 13 at the horizontal mid-plane, and the cat claw 23 is embedded in the first groove 13 to achieve support and axial positioning of the inner cylinder. The inner cylinder is provided with a second groove 24 in both the upper and lower directions, and the outer cylinder is provided with an anti-rotation pin 14 in both the upper and lower directions that matches the second groove 24, thereby achieving lateral positioning of the inner cylinder.

[0057] In the first embodiment, preferably, one end of the steam inlet pipe 3 inserted into the outer cylinder upper half 11 is detachably connected to the inner cylinder upper half 21, and the other end of the steam inlet pipe 3 is detachably connected to the steam inlet valve 4. After the steam comes out of the steam inlet valve 4, it enters the steam inlet chamber 20 of the inner cylinder through the steam inlet pipe 3, and enters the flow vane while rotating in the steam inlet chamber 20. A gasket 5 is provided between the steam inlet pipe 3 and the steam inlet valve 4. Therefore, when the cylinder is opened for maintenance, it is only necessary to release the connection between the steam inlet pipe 3 and the steam inlet valve 4, remove the gasket 5 between the steam inlet pipe 3 and the steam inlet valve 4, withdraw the steam inlet pipe 3 from the outer cylinder upper half 11 by a certain distance, separate the steam inlet pipe 3 from the inner cylinder upper half 21, and then the outer cylinder upper half 11 and the steam inlet pipe 3 can be lifted away together without cutting the steam pipeline to lift the steam inlet valve 4, which can fully simplify the on-site construction process, reduce the construction workload, and reduce the maintenance cost of the unit.

[0058] Preferably, the end of the steam inlet spigot 3 inserted into the outer cylinder upper half 11 is provided with a first annular plug-in component 31 along the circumferential direction, and the inner cylinder upper half 21 is provided with a first annular plug-in groove 25 on the end surface at the steam inlet, and the first annular plug-in component 31 is inserted into the first annular plug-in groove 25. Thus, a detachable connection between the end of the steam inlet spigot 3 inserted into the outer cylinder upper half 11 and the inner cylinder upper half 21 is realized. When the cylinder is opened, the first annular plug-in component 31 can be withdrawn from the first annular plug-in groove 25 by directly moving the steam inlet spigot 3, so as to realize the separation of the steam inlet spigot 3 and the inner cylinder upper half 21, which is very convenient to operate. In order to ensure that the first annular plug-in component 31 is completely withdrawn from the first annular plug-in groove 25 by moving the steam inlet spigot 3, the thickness of the gasket 5 should not be less than the length of the first annular plug-in component 31 inserted into the first annular plug-in groove 25, so as to provide sufficient moving space for the steam inlet spigot 3.

[0059] Preferably, the cross-sectional shape of the first annular connector 31 is L-shaped, and the L-shaped first annular connector 31 includes a first connecting portion and a first plugging portion which are perpendicular to each other, the first connecting portion is connected to the steam inlet pipe 3 , and the first plugging portion cooperates with the first annular plugging groove 25 .

[0060] In the steam inlet chamber 20 of the inner cylinder with single-side steam inlet, an unbalanced force proportional to the steam inlet pressure and the size of the steam inlet will be generated on the opposite side of the steam inlet. Therefore, in this embodiment, a self-balancing component for offsetting the unbalanced force in the steam inlet chamber 20 is provided on the upper half 21 of the inner cylinder, and the self-balancing component is provided on the opposite side of the steam inlet. By offsetting the unbalanced force in the steam chamber 20 by the self-balancing component, the center position of the inner cylinder and the radial clearance for flow can be guaranteed.

[0061] Preferably, self-balancing interfaces are correspondingly provided on the outer cylinder upper half 11 and the inner cylinder upper half 21, and the self-balancing interfaces are located on the opposite side of the steam inlet. The self-balancing component includes a self-balancing plug 6 provided at the self-balancing interface, one end of the self-balancing plug 6 is closed and the other end is open, the open end of the self-balancing plug 6 is inserted into the outer cylinder upper half 11 and connected to the inner cylinder upper half 21, and the open end of the self-balancing plug 6 is communicated with the steam inlet chamber 20, thereby forming a self-balancing space on the opposite side of the steam inlet.

[0062] Preferably, one end of the self-balancing cannula 6 inserted into the outer cylinder upper half 11 is detachably connected to the inner cylinder upper half 21, and the other end of the self-balancing cannula 6 is connected to the outer cylinder upper half 11. When the cylinder is opened for maintenance, the self-balancing cannula 6 can be withdrawn from the outer cylinder upper half 11 by a certain distance to separate the self-balancing cannula 6 from the inner cylinder upper half 21, thereby facilitating the lifting of the outer cylinder upper half 11.

[0063] Preferably, the end of the self-balancing cannula 6 inserted into the outer cylinder upper half 11 is provided with a second annular plug-in piece 61 along the circumferential direction, and the inner cylinder upper half 21 is provided with a second annular plug-in groove 26 on the end surface at the self-balancing interface, and the second annular plug-in piece 61 is inserted into the second annular plug-in groove 26. When the cylinder is opened, the second annular plug-in piece 61 can be withdrawn from the second annular plug-in groove 26 by directly moving the self-balancing cannula 6, so that the self-balancing cannula 6 and the inner cylinder upper half 21 are separated, and the operation is very convenient.

[0064] Preferably, the cross-section of the second annular connector 61 is L-shaped, and the L-shaped second annular connector 61 includes a second connecting portion and a second plugging portion perpendicular to each other, the second connecting portion is connected to the self-balancing plug tube 6, and the second plugging portion cooperates with the second annular plugging groove 26.

[0065] In addition, the inner cylinder upper half 21 and the inner cylinder lower half 22 are connected by the inner cylinder bolts 8, and the outer cylinder upper half 11 and the outer cylinder lower half 12 are connected by the outer cylinder bolts 9. Considering the space requirements for the installation, maintenance and disassembly of the outer cylinder bolts 9 at the center dividing surface of the outer cylinder in the steam inlet area, the bolt holes on the center dividing surface flange of the outer cylinder at this location are arranged in reverse, that is, the threads are on the outer cylinder upper half 12, and the smooth holes are on the outer cylinder lower half 12.

[0066] Embodiment 2

[0067] like Figure 4 and Figure 5 As shown in FIG. 1 , the second embodiment of the steam turbine steam inlet structure of the present invention is shown in FIG. The second embodiment is basically the same as the first embodiment, and the similarities are not repeated here. The difference is that Figure 4 As shown, the second embodiment adopts the lower half steam inlet, and the steam inlet port is opened on the outer cylinder lower half 12 and the inner cylinder lower half 22. The steam inlet plug 3 is inserted into the outer cylinder lower half 12 at the steam inlet port and connected with the inner cylinder lower half 22. The inner cylinder lower half 22 is provided with a first annular plug groove 25 on the end face at the steam inlet port, and the first annular plug-in piece 31 on the steam inlet plug 3 is inserted into the first annular plug groove 25.

[0068] Correspondingly, in the second embodiment, the self-balancing interface is also provided on the outer cylinder lower half 12 and the inner cylinder lower half 22, the open end of the self-balancing tube 6 is inserted into the outer cylinder lower half 12 from the self-balancing interface and connected to the inner cylinder lower half 22, the other end of the self-balancing tube 6 is connected to the outer cylinder lower half 12, and the inner cylinder lower half 22 is provided with a second annular plug-in groove 26 on the end face at the self-balancing interface, and the second annular plug-in component 61 is inserted into the second annular plug-in groove 26.

[0069] In the second embodiment, the cat claw 23 is arranged on the upper half 21 of the inner cylinder, and the first groove 13 is opened on the upper half 11 of the outer cylinder.

[0070] Figure 5A schematic diagram of the fluid domain in the steam inlet chamber 20 of the tapered cross-section single-side tangential steam inlet volute type of the second embodiment is shown.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A steam turbine steam inlet structure, comprising an outer cylinder and an inner cylinder arranged inside the outer cylinder, wherein a steam inlet chamber (20) is formed inside the inner cylinder, characterized in that: The outer cylinder and the inner cylinder are provided with steam inlets correspondingly, and a steam inlet insert (3) is provided at the steam inlet. The steam inlet insert (3) is inserted into the outer cylinder and connected to the inner cylinder and communicated with the steam inlet chamber (20). The steam inlet chamber (20) is a volute type with a tapered cross section. The inner cylinder is provided with a self-balancing component for counteracting the unbalanced force in the steam inlet chamber (20), and the self-balancing component is arranged on the opposite side of the steam inlet; The outer cylinder and the inner cylinder are provided with self-balancing interfaces correspondingly, and the self-balancing interfaces are located on the opposite side of the steam inlet. The self-balancing component comprises a self-balancing plug (6) provided at the self-balancing interface, one end of the self-balancing plug (6) is closed and the other end is open, and the open end of the self-balancing plug (6) is inserted into the outer cylinder and connected to the inner cylinder and communicated with the steam inlet chamber (20).

2. The steam turbine steam inlet structure according to claim 1, characterized in that: The steam inlet chamber (20) is of a tapered cross-section volute type designed using a constant speed moment calculation method, a constant velocity calculation method, a variable speed calculation method, or a variable speed moment calculation method.

3. The steam turbine steam inlet structure according to claim 1, characterized in that: One end of the steam inlet pipe (3) inserted into the outer cylinder is detachably connected to the inner cylinder, and the other end of the steam inlet pipe (3) is detachably connected to a steam inlet valve (4), and a gasket (5) is provided between the steam inlet pipe (3) and the steam inlet valve (4).

4. The steam turbine steam inlet structure according to claim 3, characterized in that: A first annular plug-in component (31) is circumferentially provided at one end of the steam inlet plug-in pipe (3) inserted into the outer cylinder, and a first annular plug-in groove (25) is provided on the end surface of the inner cylinder at the steam inlet port, and the first annular plug-in component (31) is inserted into the first annular plug-in groove (25).

5. The steam turbine steam inlet structure according to claim 1, characterized in that: One end of the self-balancing cannula (6) inserted into the outer cylinder is detachably connected to the inner cylinder, and the other end of the self-balancing cannula (6) is connected to the outer cylinder.

6. The steam turbine steam inlet structure according to claim 5, characterized in that: A second annular connector (61) is circumferentially provided at one end of the self-balancing insert pipe (6) inserted into the outer cylinder, and a second annular connector groove (26) is provided on the end surface of the inner cylinder at the self-balancing interface, and the second annular connector (61) is inserted into the second annular connector groove (26).

7. The steam turbine steam inlet structure according to claim 1, characterized in that: The outer cylinder comprises an outer cylinder upper half (11) and an outer cylinder lower half (12) connected at a horizontal mid-plane, and the inner cylinder comprises an inner cylinder upper half (21) and an inner cylinder lower half (22) connected at a horizontal mid-plane; the outer cylinder upper half (11) and the inner cylinder upper half (21) are correspondingly provided with the steam inlet, or the outer cylinder lower half (12) and the inner cylinder lower half (22) are correspondingly provided with the steam inlet.

8. The steam turbine steam inlet structure according to claim 1, characterized in that: The first-stage stationary blades (7) in the inner cylinder are stationary blades with a large steam inlet angle that matches the steam outlet angle of the steam inlet chamber (20).

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