Combined steam turbine admission volute and steam turbine cylinder

Abstract

The utility model discloses a combined type steam turbine admission volute and a steam turbine cylinder, the combined type steam turbine admission volute comprises a gradually-shrinking unit and a non-gradually-shrinking unit which are respectively formed, and the gradually-shrinking unit and the non-gradually-shrinking unit are connected through welding. Through the innovative design of split casting and welding connection, the manufacturing threshold of the small-size volute is remarkably reduced on the premise of not depending on an additional complex process, and meanwhile the molded line precision and the flowing efficiency are considered.

Description

Technical Field

[0001] This utility model relates to a combined steam turbine inlet volute and steam turbine cylinder, belonging to the field of steam turbine power generation. Background Technology

[0002] With the continuous research on efficient steam inlet structures for steam turbines, the tapered tangential steam inlet volute structure, as a low-pressure-loss steam inlet structure, has been widely used in the past decade. Various studies and engineering practices have shown that the tapered tangential steam inlet volute has good aerodynamic performance, good uniformity of steam velocity and flow rate at the volute outlet, and can effectively reduce steam inlet pressure loss.

[0003] Currently, this structure is mostly used in steam turbine units of 50MW and above. When applied to smaller power units, its overall volute size is small, and the diameter of the volute inlet pipe is small, especially the opening size of the volute outlet, which is usually less than 25mm. The tapered volute structure required to form a uniform flow field is also quite complex. This results in a small casting cross-sectional area, making it impossible to guarantee the size of the tapered volute. Sand removal is difficult and incomplete casting is prone to occur. The overall casting process is difficult and risky. After final molding, the inner wall cannot be polished, the inlet chamber is not smooth, and the inlet pressure loss is increased. Utility Model Content

[0004] The purpose of this utility model is to provide a combined steam turbine inlet volute and steam turbine cylinder to address the above-mentioned problems, which significantly reduces the casting difficulty of small-sized volutes and avoids casting defects caused by complex profiles and small cross-sectional areas.

[0005] The technical solution adopted in this utility model is as follows:

[0006] A combined steam turbine inlet volute includes separately formed tapered and non-tapered units, which are connected by welding.

[0007] Alternatively, the steam outlet of the combined steam turbine inlet volute has a profile formed by a tapered profile and a common confluence surface, wherein the common confluence surface is the inner ring of the volute outlet and the inner profile of the non-tapered unit; the tapered unit and the non-tapered unit are welded to the transition section between the tapered profile and the common confluence surface.

[0008] Alternatively, both the non-tapered unit and the tapered unit may have an upper shell and a lower shell.

[0009] Alternatively, the mating surface of the upper and lower housings can be the horizontal split surface of the cylinder.

[0010] Alternatively, the upper and lower housings can be connected by a flange.

[0011] A steam turbine cylinder, comprising the combined steam turbine inlet volute as described above.

[0012] Alternatively, the turbine cylinder may include an outer cylinder and an inner cylinder, with the combined turbine inlet volute serving as part of the inner cylinder and integrally formed.

[0013] Alternatively, the turbine cylinder may be a single cylinder, and the combined turbine inlet volute may be integrally formed as part of the single cylinder.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are:

[0015] This invention provides a combined steam turbine inlet volute, which, through an innovative design of separate casting and welding, significantly lowers the manufacturing threshold for small-sized volutes without relying on additional complex processes, while simultaneously ensuring profile accuracy and flow efficiency. By decomposing complex problems into simple modules and achieving high performance through standardized processes, it provides a feasible path for the development of miniaturized and high-efficiency steam turbines. It solves the casting difficulties of inlet volutes for small-power steam turbines below 50MW, enabling the smooth application of tangential inlet tapering volute structures in this field, reducing inlet pressure loss and effectively improving unit efficiency. Furthermore, as the inlet pressure of current small-power units continues to increase towards ultra-high pressure and subcritical parameters, and the inlet size further decreases, the application of combined inlet volutes will become increasingly widespread. Attached Figure Description

[0016] Figure 1 This is a structural diagram of the intake volute.

[0017] Figure 2 This is a longitudinal section view of the steam inlet volute.

[0018] Figure 3 This is a diagram of a tangentially converging steam inlet chamber.

[0019] Figure 4 It is a tapered line graph.

[0020] The markings in the diagram are: 1-recessed unit, 2-non-recessed unit, 3-recessed profile, 4-common meeting surface, 5-upper shell, 6-lower shell, 7-flange. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings.

[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0023] A type of combined steam turbine inlet volute, such as Figure 1-4 As shown, it includes separately formed tapered unit 1 and non-tapered unit 2, which are connected by welding.

[0024] From the perspective of volute casing casting technology, the small size of the steam outlet is a major challenge in the overall casting of the volute casing. Casting it separately along the inner and outer rings of the steam outlet allows the internal chambers of the volute casing to be opened, thus reducing the difficulty of steam intake and simplifying the internal chamber structure. The tapered unit 1 is responsible for accelerating steam flow and regulating pressure. Its profile is complex; separate casting avoids problems such as insufficient casting and difficulty in sand removal caused by excessively fine profiles in integral casting. Furthermore, the inner wall of the tapered unit 1 can be individually precision-machined to ensure dimensional accuracy and surface roughness. The non-tapered unit 2, serving as the steam outlet, maintains structural stability and guides steam flow towards it. Its relatively simple structure simplifies the processing flow and reduces overall costs. The tapered unit 1 and the non-tapered unit 2 are cast independently, avoiding casting defects caused by complex profiles and small cross-sectional areas when casting small-sized volutes as a whole. This increases the casting cross-sectional area, improves the fluidity of the molten metal, and reduces the scrap rate. Furthermore, it allows for precision machining of the inner wall before welding to ensure accurate steam inlet profile dimensions and reduce roughness. By combining separate casting with welding, the problem of integral molding caused by the small size of the volute in small-power units is solved, enabling low-pressure-loss flow even under small-size conditions with complex profile structures.

[0025] As another specific implementation, the steam outlet of the combined steam turbine inlet volute has a profile formed by the convergence line 3 and the common confluence surface 4. The common confluence surface 4 is the inner ring of the volute outlet and is the inner profile of the non-convergence unit 2. The convergence unit 1 and the non-convergence unit 2 are welded to the transition section between the convergence line 3 and the common confluence surface 4.

[0026] The profile design is existing technology. This solution splits the profile and corresponds it to the tapered unit 1 and the non-tapered unit 2. By casting the complex profile area of ​​the tapered profile 3 and the stable structural area of ​​the common confluence surface 4 separately, the risk of casting defects caused by geometric shrinkage and small size in the transition section can be significantly reduced. The area of ​​the tapered profile 3 and the rest of the volute structure are cast as tapered unit 1, and the common confluence surface 4 is non-tapered unit 2. The separate design significantly reduces the casting difficulty of the complex profile of the small-sized volute, allowing the tapered unit 1 to be independently precision machined, ensuring profile accuracy and inner wall smoothness, reducing steam flow separation and pressure loss, and facilitating subsequent welding and finishing. The welding position is selected at the transition section between the tapered profile 3 and the common confluence surface 4, which avoids direct action on the high-stress area, utilizes the gentle geometric characteristics of the transition section to reduce welding deformation, and facilitates secondary processing of the weld area.

[0027] In another specific embodiment, both the non-tapered unit 2 and the tapered unit 1 have an upper shell 5 and a lower shell 6. During casting, the volute is divided into four parts: the upper and lower halves of the non-tapered portion, and the upper and lower halves of the tapered portion, which are cast separately. The split structure of the upper shell 5 and the lower shell 6 allows for independent casting and machining of each half, significantly reducing the casting difficulty of small-sized volutes. Furthermore, the inner wall of each half can be individually polished with high precision after separation. The design of the upper shell 5 and the lower shell 6 also facilitates alignment and adjustment during assembly and subsequent maintenance.

[0028] In another specific embodiment, the mating surface of the upper housing 5 and the lower housing 6 is the horizontal split surface of the cylinder. By aligning the split surface of the volute housing with the horizontal split surface of the cylinder, seamless integration of the volute housing and cylinder structure is achieved, ensuring the sealing of the split mating surface and the assembly alignment accuracy.

[0029] In another specific embodiment, the upper housing 5 and the lower housing 6 are connected by a flange 7. The flange 7 connection provides a standardized and highly reliable assembly method, ensuring precise alignment and sealing of the upper and lower housings 6 through bolt tightening, effectively preventing steam leakage and maintaining a stable high-pressure environment inside the volute. Simultaneously, the flange 7 interface design is adapted to the horizontal split-face structure of the cylinder, facilitating rapid disassembly and integration of the volute with other cylinder components.

[0030] A steam turbine cylinder includes a combined steam turbine inlet volute as described above.

[0031] In another specific embodiment, the turbine cylinder includes an outer cylinder and an inner cylinder, with the combined turbine inlet volute serving as part of the inner cylinder and integrally formed. Specifically, the outer cylinder features a common upper and lower half-structure design, and the inner cylinder is integrated with the combined turbine inlet volute. In this embodiment, the inner cylinder is also divided into four parts: the upper and lower half-shells 6 of the non-recessed unit 2, and the upper and lower half-shells 6 of the receding unit 1. The other structures of the inner cylinder are integrated with the receding unit 1, formed integrally by casting. The receding unit 1 and the non-recessed unit 2 are welded together, and the upper half-shell 5 and the lower half-shell 6 are connected by bolts. This integrated design with the inner cylinder enhances the overall structural integrity, reduces the risk of steam leakage, and optimizes flow uniformity.

[0032] In another specific implementation, the turbine cylinder is a single cylinder, and the combined turbine inlet volute is integrally formed as part of the single cylinder. Specifically, the single cylinder is integrated with the combined turbine inlet volute. In this embodiment, the single cylinder is also divided into four parts: the upper shell 5 and lower shell 6 of the non-recessed unit 2, and the upper shell 5 and lower shell 6 of the recessed unit 1. The other structures of the single cylinder are integrated with the recessed unit 1 and integrally formed by casting. The recessed unit 1 and the non-recessed unit 2 are welded together, and the upper shell 5 and lower shell 6 are connected by bolts. By eliminating the inner cylinder structure, the cylinder hierarchy is simplified, the length of the inlet flow channel is shortened, and the dimensional accumulation error caused by multi-cylinder assembly is avoided. At the same time, the single-cylinder integral casting process improves manufacturing efficiency and rigidity, adapting to the compact and lightweight requirements of small-power units.

[0033] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. The present utility model extends to any new features or combinations disclosed in this specification, and any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model. It is obvious to those skilled in the art that the present utility model is not limited to the details of the above exemplary embodiments, and that detailed technical features not disclosed in this embodiment, such as specific structures and related parameters, are all prior art, which can be obtained by those skilled in the art from the prior art; the connection method can be a fixed connection, a detachable connection, or an integral part; it can be a fixed connection, a movable connection, or a hinged connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific manner of the above terms in the embodiments of the present utility model according to the specific circumstances, and the present disclosure does not specifically limit this aspect.

Claims

1. A combined steam turbine inlet volute, characterized in that: It includes separately formed tapered and non-tapered units, which are connected by welding.

2. The combined steam turbine inlet volute as described in claim 1, characterized in that: The steam outlet of the combined steam turbine inlet volute has a profile formed by a tapered profile and a common confluence surface. The common confluence surface is the inner ring of the volute outlet and is the inner profile of the non-tapered unit. The tapered unit and the non-tapered unit are welded to the transition section between the tapered profile and the common confluence surface.

3. The combined steam turbine inlet volute as described in claim 1, characterized in that: Both the non-tapered unit and the tapered unit have an upper shell and a lower shell.

4. The combined steam turbine inlet volute as described in claim 3, characterized in that: The mating surface between the upper and lower shells is the horizontal split surface of the cylinder.

5. The combined steam turbine inlet volute as described in claim 3, characterized in that: The upper and lower shells are connected by a flange.

6. A steam turbine cylinder, characterized in that: Includes the combined steam turbine inlet volute as described in any one of claims 1-5.

7. The turbine cylinder as described in claim 6, characterized in that: The turbine cylinder includes an outer cylinder and an inner cylinder, and the combined turbine inlet volute is integrally formed as part of the inner cylinder.

8. The steam turbine cylinder as described in claim 6, characterized in that: The turbine cylinder is a single cylinder, and the combined turbine inlet volute is integrally formed as part of the single cylinder.

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