Low-resistance exhaust nozzle for steam turbine

Abstract

This invention relates to the field of steam turbine technology, specifically to a low-resistance exhaust throat for steam turbines. The throat includes a shell with multiple sets of tapered guide holes on its sidewalls. Multiple rows of streamlined, staggered guide columns are arranged inside. Guide sleeves are fitted at both ends of the guide columns. A C-shaped metal elastic ring is fitted into the annular groove of the guide sleeve, and the C-shaped opening is fitted with an elastic overlapping compensation piece. The tapered guide holes have bidirectional tapered surfaces that fit against the elastic rings. A sliding gap is reserved between the guide holes and the guide sleeves, and an axial gap is reserved between the guide columns and the sealing cover. A fixed sliding groove is provided inside the guide holes, and a fixed slider is fitted into the guide sleeves. The guide columns have guide grooves and vibration-absorbing holes, and are fitted with fluororubber sealing gaskets. This achieves elastic floating and thermal expansion self-adaptation of the guide columns, resulting in a low-resistance, regularized flow field. This solves the problems of rigid jamming, high flow resistance, and vibration fatigue in traditional structures, improving exhaust efficiency and equipment operational reliability.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, specifically to a low-resistance exhaust throat for steam turbines. Background Technology

[0002] In large steam turbine units, the exhaust throat, as a key transitional component connecting the low-pressure cylinder and the condenser, typically employs a welded shell structure. To overcome the enormous negative pressure environment inside the shell, an internal support truss composed of channel steel or steel pipes is generally installed, along with fixed guide vanes within the exhaust passage to guide the high-speed airflow uniformly into the condenser. However, under actual operating conditions, this structure exhibits significant flow losses. Due to the extremely high exhaust velocity, the complex support truss forms a substantial solid obstruction, resulting in a significant increase in exhaust back pressure, directly reducing the unit's thermal efficiency.

[0003] To address the aforementioned issues, existing technologies offer several solutions. For instance, utility model patent application number 202320380993.4 provides a frame-type welded exhaust cylinder for steam turbines. This application discloses the following solution: the frame-type load-bearing structure formed by welding channel steel and the internal flow channel design fundamentally improve the structural rigidity and flow performance of the exhaust cylinder, eliminating the material waste and excessive secondary flow in the internal flow channel caused by traditional thick panel structures. At the same time, the upper and lower half-separated assembly and the integrated design of the closed extraction chamber can stably realize the exhaust steam guiding and extraction functions, alleviating the problem of low unit thermal efficiency caused by large total pressure loss. It can be adapted to the stable operation and use of small and medium-sized steam turbines in the scenarios of high-efficiency exhaust and lightweight manufacturing. However, this solution has certain limitations in actual use: the welded and fixed frame and flow channel structure have no self-adjustment capability and are prone to operational failures due to thermal expansion deviation, scale buildup and jamming, and stress fatigue, such as poor sealing, decreased flow efficiency, and insufficient rigidity. Summary of the Invention

[0004] The purpose of this invention is to provide a low-resistance exhaust throat for steam turbines to solve the problem that the flow channel lacks adaptive adjustment capability due to thermal expansion.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A low-resistance exhaust throat for a steam turbine includes a throat shell with multiple tapered guide holes on its sidewall. Multiple rows of guide columns are arranged inside the throat shell, each with a streamlined axial cross-section. The rows of guide columns are staggered. Guide sleeves are provided at both ends of each guide column, which penetrates the guide sleeve and is slidably connected to it. An annular groove is provided on the sidewall of the guide sleeve, and a metal elastic ring is fitted inside the annular groove. The horizontal cross-section of the metal elastic ring is C-shaped. Both ends of the guide columns are elastically connected to the metal elastic ring. The tube is supported within a tapered guide hole. A sliding gap of 1-2 mm is provided between the tapered guide hole and the guide sleeve. A first tapered surface is provided within the tapered guide hole. The diameter of the tapered guide hole gradually decreases from the outside to the inside of the throat shell. The first tapered surface contacts the outside of the metal elastic ring. When the metal elastic ring deforms to fit the annular groove on the inside, the diameter of the metal elastic ring is larger than the small end diameter of the tapered guide hole. A sealing cap is fitted on the outside of the tapered guide hole. Both ends of the guide column and the sealing cap have an axial gap of 1.5-2 mm.

[0006] By creating multiple conical guide holes with internal first conical surfaces on the sidewall of the throat casing, the diameter of which gradually decreases from the outside to the inside of the throat casing. The design also incorporates multiple rows of streamlined, staggered guide columns within the throat casing. These guide columns pass through guide sleeves at both ends and slide together. A C-shaped metal elastic ring is fitted into the annular groove on the sidewall of the guide sleeve, elastically supporting both ends of the guide columns within the conical guide holes. A 1-2 mm sliding gap is maintained between the conical guide hole and the guide sleeve, allowing the metal elastic ring to deform to a diameter larger than the smaller end diameter of the conical guide hole when it fits against the annular groove. A sealing cap is fitted onto the outside of the conical guide hole, with a 1.5-2 mm axial gap between the guide columns and the sealing cap. This design eliminates the conventional structure of rigidly fixed turbine exhaust throat guide components lacking thermal expansion self-compensation capabilities, thus preventing thermal expansion issues during high-temperature turbine operation. This system addresses issues such as jamming, stress concentration, sealing failure, and excessive flow resistance caused by expansion and deformation. It avoids problems like airflow leakage, guide column displacement and deformation, increased erosion and wear on the inner wall of the throat, and support structure failure during steam exhaust. It can accurately adapt to temperature changes and thermal expansion displacement during turbine operation under varying conditions. The radial floating elastic support of the guide column is achieved through the elastic fit between the C-shaped metal elastic ring and the first conical surface of the conical guide hole. The limited sliding and axial clearances provide sufficient compensation space for the thermal deformation of the guide column. The streamlined staggered arrangement of the guide columns optimizes the exhaust flow distribution and significantly reduces exhaust flow resistance. The sealing performance of the throat is ensured by the structure of the sealing cover and clearance fit. This effectively improves the structural stability, operational reliability, and adaptive adjustment capability of the exhaust throat under high temperature and variable pressure conditions, significantly reduces exhaust flow losses, improves turbine exhaust efficiency, and extends the overall service life of the guide column, guide sleeve, and throat shell.

[0007] Preferably, a conical block is provided on the side of the conical guide hole away from the throat housing. The conical block is fixedly installed inside the port of the conical guide hole. A second conical surface is provided on the side of the conical block opposite to the throat housing. The second conical surface is opposite to the first conical surface and contacts the outer side of the metal elastic ring.

[0008] By fixing a conical block inside the conical guide hole on the side away from the throat housing, and setting a second conical surface arranged in the opposite direction to the first conical surface on the side of the conical block opposite to the throat housing, the second conical surface always maintains contact with the outer side of the metal elastic ring. This design addresses the core problem of cold contraction deformation of the throat housing under low-pressure or low-temperature conditions, which leads to the first conical surface separating from the metal elastic ring and the failure of the elastic floating support effect of the guide column. With the bidirectional conical clamping and limiting structure formed by the reverse second conical surface and the first conical surface, a stable radial constraint and support can be continuously provided for the metal elastic ring when the throat housing cold contracts, ensuring that the metal elastic ring will not separate from the conical surface regardless of whether it is in a state of high-temperature expansion or low-temperature contraction. Maintaining a reliable elastic support state at all times, effectively preserving the elastic floating adjustment function of the guide column, and forming a strong correlation and synergistic effect with the core design of the conical guide hole, the first conical surface, the C-shaped metal elastic ring, the sliding gap, and the axial gap, further enhancing the core beneficial effects of thermal expansion adaptive compensation, jam-free operation, structural stability, and reliable sealing, eliminating hidden dangers such as floating failure, support imbalance, and seal disconnection caused by cold contraction, significantly improving the adaptive adjustment capability and operational reliability of the exhaust throat under all operating conditions and a wide temperature range, ensuring that the guide column is always in a stable elastic support state, continuously optimizing the exhaust flow field distribution, reducing flow resistance, and ensuring that the turbine exhaust efficiency and the overall service life of the equipment are not affected by operating condition fluctuations.

[0009] Preferably, the streamlined cross-section of the guide column is a teardrop shape, with the head of the teardrop-shaped cross-section facing the airflow inlet and the tail having a gradually narrowing section along the airflow direction.

[0010] By designing the guide column with a teardrop-shaped cross-section, ensuring the head of the teardrop precisely faces the airflow inlet, and incorporating a gradually narrowing section at the tail end along the airflow direction, this design optimizes the streamlined cross-section based on the existing staggered, elastically floating guide column structure. The smooth, frontal head significantly reduces the frontal impact resistance and airflow disturbance of high-speed exhaust airflow, while the gradually narrowing tail smoothly guides the airflow along the wall for stable flow, effectively suppressing boundary layer separation, eliminating vortices and wake losses at the tail end of the guide column, and reducing flow losses at the source. The kinetic energy dissipation significantly reduces exhaust flow resistance and back pressure inside the throat. This structure, together with the core designs such as multiple rows of staggered guide columns, C-shaped metal elastic ring radial elastic support, and conical guide holes with thermal expansion self-adaptation, forms a synergistic effect, further improving the flow guiding efficiency and flow field regularity of the guide columns. This allows the guide columns to maintain a highly efficient and low-resistance flow guiding state during thermal expansion and contraction under varying operating conditions, comprehensively improving the flow performance and operational stability of the exhaust throat. This better achieves the core technical objectives of low air resistance, high self-adaptation, and long service life, helping to reduce turbine exhaust losses and improve the overall thermal efficiency of the unit.

[0011] Preferably, a fixed groove is provided on the inner side of the tapered guide hole, and a fixed slider is provided on the side wall of the guide sleeve, the fixed slider being slidably connected to the fixed groove.

[0012] By setting a fixed groove on the inner side of the tapered guide hole and setting a fixed slider on the corresponding side wall of the guide sleeve that can slide with the fixed groove, the structural design ensures that the fixed slider and the fixed groove always maintain a precise sliding connection. This design can form a stable circumferential constraint on the guide sleeve, preventing problems such as circumferential rotation, deflection, and misalignment of the guide sleeve during the process of the guide column being impacted by high-speed airflow, undergoing thermal expansion and contraction due to temperature changes, and radial elastic floating. It effectively prevents the C-shaped metal elastic ring in the annular groove from becoming skewed, twisted, experiencing localized accelerated wear, or having poor contact with the first conical surface and support failure due to the rotation of the guide sleeve. This ensures that the metal elastic ring is always in contact with the first conical surface. The surface maintains a uniform and stable fit and support state, ensuring the stable functioning of core structures such as the sliding connection between the guide column and the guide sleeve, the elastic support of the metal elastic ring, the guidance of the conical guide hole, and the reserved sliding gap and axial gap. This further improves the accuracy and synchronization of the movement of the guide sleeve and the guide column, eliminating hidden dangers such as support imbalance, seal disconnection, increased airflow disturbance, and increased flow resistance caused by circumferential rotation. It allows the guide column to maintain a regular elastic floating posture in complex operating environments with high temperature, variable pressure, and variable working conditions, continuously optimizing the exhaust flow field distribution, stably achieving low air resistance exhaust effect, and significantly improving the durability, operational stability, and long-term working reliability of the overall exhaust throat structure.

[0013] Preferably, a buffer ring is provided between the annular groove and the metal elastic ring, a sealing groove is provided on the side of the sliding gap in the conical guide hole opposite to the metal elastic ring, a sealing ring is provided in the sealing groove, and a sealing gasket is provided in each of the axial gaps. The buffer ring, sealing ring and sealing gasket are all made of fluororubber.

[0014] By setting a buffer ring between the annular groove and the metal elastic ring, setting a sealing ring in the sealing groove on the side opposite to the sliding gap and the metal elastic ring, and setting a sealing gasket in the axial gap between the two ends of the guide column and the sealing cover, and by using fluororubber for all three components—buffer ring, sealing ring, and sealing gasket—the excellent high-temperature resistance, corrosion resistance, aging resistance, and flexible sealing properties of fluororubber are utilized to fill the sliding gap, axial gap, and fitting gap between the annular groove and the metal elastic ring, which are specifically reserved for the elastic floating support of the guide column. This creates a comprehensive, multi-level sealing barrier, effectively preventing internal leaks in the turbine exhaust pipe under high-temperature and high-negative-pressure operating conditions. This flexible seal addresses the issues of steam leakage and external air infiltration. It also possesses excellent deformation adaptability, ensuring that the elastic deformation of the metal elastic ring and the radial elastic floating movement of the guide sleeve and flow guide column are not hindered. This improves the overall sealing performance and wide-temperature-range adaptability of the exhaust throat, resolving the industry pain point of traditional rigid seals or ordinary sealing materials easily hardening, cracking, and failing under high-temperature conditions, leading to poor sealing. It ensures that the flow guide column maintains stable elastic support and sealing throughout the entire temperature range and under varying operating conditions, continuously optimizing the exhaust flow field distribution, reducing flow resistance, and effectively improving the turbine exhaust efficiency and the long-term reliability and service life of the equipment.

[0015] Preferably, the surface of the guide column is provided with a guide groove along the airflow direction, and the depth of the guide groove is 0.2 to 0.5 mm.

[0016] By creating guide grooves with a depth of 0.2–0.5 mm along the airflow direction on the surface of a guide column with a teardrop-shaped cross-section, a head facing the airflow inlet, and a gradually narrowing tail, this design further refines and regulates the airflow on the guide column surface, building upon the teardrop-shaped streamlined drag reduction. This effectively disrupts the thick boundary layer formed by high-speed exhaust on the column surface, suppressing airflow turbulence, eddies, and local backflow. It also reduces frictional resistance and flow energy dissipation between the airflow and the guide column surface, allowing the exhaust airflow to pass smoothly and stably along the guide grooves, further reducing exhaust flow resistance and the internal throat area. Back pressure, building upon the already achieved benefits of reducing frontal airflow impact, suppressing boundary layer separation, and eliminating tail wake losses, further enhances the core performance of low-resistance flow guidance. This allows the overall streamline optimization of the guide column and the surface groove guidance to form a dual drag reduction system. At the same time, this shallow groove design does not affect the structural strength of the guide column and is fully compatible with the elastic floating and thermal expansion adaptive operating state of the guide column. This comprehensively improves the regularity and flow efficiency of the exhaust steam flow field, further highlighting the technical advantages of low air resistance and high flow guidance efficiency of this invention, and better solving the problems of large flow losses and low unit thermal efficiency in traditional exhaust throat pipes.

[0017] Preferably, the C-shaped opening of the metal elastic ring is provided with an insertion interface, the insertion interface is provided with an elastic overlap compensation piece, one end of the elastic overlap compensation piece is provided with an insertion segment, and the insertion segment is slidably connected in the insertion interface.

[0018] By setting an insertion interface at the C-shaped opening of a metal elastic ring, and installing an elastic overlapping compensation piece inside the insertion interface, with one end of the elastic overlapping compensation piece slidably connected to the insertion interface, this structure can improve the problems of stress concentration, uneven deformation, weakened support force, and failure to fit with the first conical surface due to excessive expansion of the opening at high temperatures that are common in traditional C-shaped metal elastic rings. The elastic overlapping compensation piece can adaptively expand and contract and overlap in sync with the radial elastic deformation of the C-shaped ring, always maintaining the integrity of the overall outline of the C-shaped ring and the uniformity of the support force, effectively avoiding the opening... Abnormal changes in the gap can cause imbalances in the elastic support, poor local contact, and jamming of the guide sleeve. This ensures that the metal elastic ring maintains a stable and uniform fit with the first conical surface of the conical guide hole during high-temperature expansion, low-temperature contraction, and variable operating conditions. This further improves the structural strength, high-temperature durability, and support stability of the metal elastic ring, and solves the defects of traditional open-type elastic rings, such as easy deformation, easy failure, and insufficient support accuracy. It ensures that the guide column is always in a stable and reliable elastic support state under all operating conditions and a wide temperature range, continuously optimizing the exhaust flow field distribution and reducing flow resistance.

[0019] Preferably, the guide column has a vibration-absorbing hole in the radial center, the vibration-absorbing hole penetrates the entire guide column, and the vibration-absorbing hole is filled with vibration-absorbing material.

[0020] By creating vibration-absorbing holes in the radial center of the guide column and filling them with vibration-absorbing material, a damping and vibration-reducing system formed by the built-in vibration-absorbing holes and material effectively absorbs and dissipates the excitation energy, airflow pulsation, and minute vibrations generated by the high-speed exhaust airflow impacting the guide column, as well as the minor vibrations generated by the guide column during elastic floating support. This suppresses resonance, swaying, and displacement of the guide column, preventing vibration transmission from causing problems such as loosening, accelerated wear, and decreased fitting accuracy in core mating components such as the guide sleeve, metal elastic ring, and conical guide hole. This ensures that the guide column maintains a stable and regular working posture. This invention improves the structural stability and smooth operation of the guide column. The vibration-absorbing holes are radially positioned at the center, preserving the teardrop-shaped streamline profile of the guide column and maintaining its low air resistance. This design perfectly adapts to the guide column's elastic floating and thermal expansion adaptation, comprehensively optimizing the overall operating conditions of the exhaust throat, reducing the risk of vibration fatigue damage, extending the service life of the guide column and all supporting components, and enhancing the reliability and stability of the exhaust throat under high-speed airflow and complex vibration environments. This further solidifies the core technological advantages of this invention: low air resistance, high flow efficiency, and long service life.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through the design of a C-shaped metal elastic ring, bidirectional conical guide, and gap compensation thermal expansion adaptive support system, combined with elastic overlapping compensation plates and annular groove structure, the double conical surfaces continuously fit the elastic ring, and the compensation plates expand and contract synchronously with deformation to eliminate stress. The 1-2mm sliding gap and 1.5-2mm axial gap reserve sufficient space for thermal deformation, solving the problems of rigid fixing and stress concentration. It adapts to thermal expansion and contraction under all working conditions, ensures the elastic floating of the guide column, and greatly improves the support stability and adaptive capability under different working conditions.

[0022] 2. Through the design of a low-resistance flow guiding system with teardrop-shaped streamline cross section, staggered arrangement, and flow guiding grooves, combined with a tail-end tapered diameter structure, the head faces the flow to reduce airflow impact, breaks the boundary layer to suppress eddies, and multiple rows of staggered and regularized flow fields, the flow energy dissipation and back pressure increase are reduced from the source. This solves the problems of high flow resistance, high wake loss, and turbulent flow field in traditional structures, optimizes exhaust distribution, significantly reduces air resistance, and effectively improves turbine exhaust efficiency.

[0023] 3. Through the design of a durable protection system with multi-stage fluororubber sealing, vibration absorption and damping, and circumferential limiting, combined with fixed slide block, wear-resistant guide structure, full-dimensional gap filling of sealing gasket to prevent gas leakage, vibration absorption holes to dissipate vibration energy, and slide constraint guide sleeve to prevent deflection and jamming, the system solves the problems of sealing failure, vibration fatigue, and reduced fit accuracy. It is suitable for harsh working conditions with high temperature and negative pressure, reduces structural wear and maintenance frequency, and comprehensively improves the durability and long-term operational reliability of the equipment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the low-resistance exhaust throat for steam turbines according to the present invention; Figure 2 This is a front view of the throat shell of the present invention; Figure 3 for Figure 2 Cross-sectional view of AA in the middle; Figure 4 This is a top view of the throat tube housing of the present invention; Figure 5 for Figure 4 Sectional view of BB; Figure 6 for Figure 3 Enlarged view of point C in the middle; Figure 7 for Figure 5 Enlarged view of point D in the middle; Figure 8 This is a schematic diagram of the structure of the flow guide column and guide sleeve of the present invention; Figure 9 This is a schematic diagram of the structure of the guide sleeve of the present invention; Figure 10 for Figure 9 Cross-sectional view of the EE; Figure 11 This is a schematic diagram of the structure of the metal elastic ring of the present invention; Figure 12 for Figure 11 Cross-sectional view of FF.

[0025] In the figure: 1. Throat shell; 2. Conical guide hole; 201. Sliding clearance; 202. First conical surface; 203. Fixed groove; 204. Sealing groove; 3. Guide column; 301. Teardrop-shaped cross-section; 302. Guide groove; 303. Vibration absorption hole; 4. Guide sleeve; 401. Annular groove; 402. Fixed slider; 5. Metal elastic ring; 501. Insertion interface; 6. Sealing cover; 601. Axial clearance; 7. Conical block; 701. Second conical surface; 8. Sealing gasket; 9. Elastic overlap compensation piece; 901. Insertion section; 10. Steam turbine; 11. Buffer ring; 12. Sealing ring. Detailed Implementation

[0026] Please see Figures 1 to 12 This invention provides a low-resistance exhaust throat for steam turbines, the technical solution of which is as follows: A low-resistance exhaust throat for a steam turbine includes a throat shell 1, a steam turbine 10 disposed on the left side of the throat shell 1, multiple tapered guide holes 2 formed on the side wall of the throat shell 1, and multiple rows of guide columns 3 disposed inside the throat shell 1. The axial cross-section of the guide column 3 is streamlined, and the streamlined cross-section of the guide column 3 is a teardrop-shaped cross-section 301. The head of the teardrop-shaped cross-section 301 faces the direction of the airflow inlet, and the tail has a gradually narrowing section along the airflow direction. The surface of the guide column 3 has guide grooves 302 formed along the airflow direction, and the depth of the guide grooves 302 is 0.5 mm. A vibration-absorbing hole 303 is disposed in the radial center of the guide column 3, penetrating the entire guide column 3. The vibration-absorbing hole 303 is filled with a vibration-absorbing material, which is high-temperature resistant. The high-damping rubber has multiple rows of staggered guide columns 3. Guide sleeves 4 are provided at both ends of each guide column 3, with the guide column 3 penetrating through the guide sleeves 4 and slidably connected to them. An annular groove 401 is provided on the side wall of the guide sleeve 4, and a metal elastic ring 5 is fitted inside the annular groove 401. The horizontal cross-section of the metal elastic ring 5 is C-shaped, and an insertion interface 501 is provided at the C-shaped opening of the metal elastic ring 5. An elastic overlap compensation piece 9 is provided inside the insertion interface 501. One end of the elastic overlap compensation piece 9 has an insertion section 901, which is slidably connected inside the insertion interface 501. The other end of the elastic overlap compensation piece 9 is fixedly connected to one side of the opening of the metal elastic ring 5. Both ends of the guide column 3 are elastically supported by the metal elastic rings 5 ​​on a conical shape. Inside the guide hole 2, a fixed groove 203 is provided on the inner side of the tapered guide hole 2. A fixed slider 402 is provided on the side wall of the guide sleeve 4. The fixed slider 402 is slidably connected to the fixed groove 203. A sliding gap 201 of 2mm is provided between the tapered guide hole 2 and the guide sleeve 4. A first tapered surface 202 is provided inside the tapered guide hole 2. The diameter of the tapered guide hole 2 gradually decreases from the outside to the inside of the throat housing 1. The first tapered surface 202 contacts the outside of the metal elastic ring 5. A tapered block 7 is provided on the side of the tapered guide hole 2 away from the throat housing 1. The tapered block 7 is fixedly installed in the port of the tapered guide hole 2. A second tapered surface 701 is provided on the side of the tapered block 7 opposite to the throat housing 1. The second tapered surface 701 and the first tapered surface 202 are connected. Conversely, the second conical surface 701 contacts the outer side of the metal elastic ring 5, and the first conical surface 202 and the second conical surface 701 form a V-shaped angled space. The axial width of the V-shaped angled space is greater than the thickness of the metal elastic ring 5. The reserved space allows the metal elastic ring 5 to generate a small axial displacement when it contracts radially on the first conical surface 202, preventing rigid jamming caused by thermal stress. When not in operation, the metal elastic ring 5 is clamped in the middle of this space. When the metal elastic ring 5 deforms to fit the inner side with the annular groove 401, the diameter of the metal elastic ring 5 is greater than the small end diameter of the conical guide hole 2. A sealing cap 6 is fitted on the outer side of the conical guide hole 2, and both ends of the guide column 3 and the sealing cap 6 are provided with an axial gap 601, which is 2mm.A buffer ring 11 is provided between the annular groove 401 and the metal elastic ring 5. A sealing groove 204 is provided on the side of the sliding gap 201 in the conical guide hole 2 opposite to the metal elastic ring 5. A sealing ring 12 is provided in the sealing groove 204. A sliding groove is provided between the fixed slider 402 and the guide sleeve 4. The opening of the sliding groove faces the inside of the throat housing 1. When the guide sleeve 4 performs a compensation action, the sealing ring 12 can slide in the sliding groove. The sealing ring 12 is embedded in the sealing groove 204, and its sealing surface is interference-fitted with the outer periphery of the guide sleeve 4. When the guide sleeve 4 moves axially or radially, the sealing ring always maintains dynamic sealing contact. A sealing gasket 8 is provided in the axial gap 601. The materials of the buffer ring 11, sealing ring 12, and sealing gasket 8 are all fluororubber.

[0027] Working principle: Please refer to Figures 1 to 12 During normal operation of the low-resistance exhaust throat of the steam turbine, multiple teardrop-shaped streamlined guide columns 3 are staggered within the throat shell 1. The guide columns 3 pass through guide sleeves 4 at both ends and are slidably connected to them. The C-shaped metal elastic ring 5 within the annular groove 401 of the guide sleeve 4 is bidirectionally clamped and fitted by the first conical surface 202 of the conical guide hole 2 and the second conical surface 701 of the conical block 7. The elastic overlapping compensation piece 9 at the C-shaped opening closes the compensation gap. The fixed slider 402 of the guide sleeve 4 is embedded in the fixed groove 203 of the conical guide hole 2 to achieve circumferential... Limiting, a 2mm sliding gap 201 between the tapered guide hole 2 and the guide sleeve 4, and a 2mm axial gap 601 between the guide column 3 and the sealing cover 6 are reserved for deformation allowance. The fluororubber buffer ring 11, sealing ring 12, and sealing gasket 8 in the annular groove 401, sliding gap 201 and axial gap 601 are flexibly filled and sealed. The guide groove 302 on the surface of the guide column 3 regulates the airflow and the vibration absorption hole 303 in the middle dissipates the vibration. The whole forms a stable operating state with bidirectional conical surface elastic support, circumferential limiting, gap compensation, sealing and vibration reduction.

[0028] When the unit is under high-temperature thermal expansion conditions, the guide column 3 and the guide sleeve 4 expand radially due to heat, pushing the C-shaped metal elastic ring 5 to adaptively contract radially along the first conical surface 202 and the second conical surface 701. The elastic overlapping compensation piece 9 stretches and expands synchronously with the metal elastic ring 5, continuously compensating for the opening gap to avoid stress concentration. The sliding gap 201 and the axial gap 601 release thermal deformation stress synchronously. The fixed slider 402 slides along the fixed slide groove 203 to prevent the guide sleeve 4 from deflecting. The fluororubber sealing ring 12 flexibly adapts to the seal as the gap changes. The metal elastic ring 5 always maintains close contact with the bidirectional conical surface for support. The guide column 3 achieves unimpeded elastic floating. The teardrop-shaped streamline and the guide groove 302 continuously guide the flow with low resistance, without rigid jamming, support failure, or sealing leakage.

[0029] When the unit is in a low-temperature cold contraction condition, the throat shell 1 and the flow guiding component contract when cooled. The first conical surface 202 of the conical guide hole 2 expands outward as the shell contracts. The second conical surface 701 of the conical block 7 clamps the C-shaped metal elastic ring 5 in the opposite direction, keeping the elastic ring and the conical surface tightly fitted to prevent the support from falling off. The elastic overlap compensation piece 9 retracts and closes synchronously with the metal elastic ring 5, maintaining the integrity of the ring outline and uniform support. The sliding gap 201 and the axial gap 601 compensate for the amount of cold contraction. The fixed slide groove 203 and the slider continuously constrain the circumferential position of the guide sleeve 4. The fluororubber sealing ring 12 remains sealed. The flow guiding column 3 is still in a stable elastic support. The regular flow field and low air resistance flow guiding effect are not affected.

[0030] After the unit shutdown temperature drops back to normal, the guide column 3, guide sleeve 4, C-shaped metal elastic ring 5 and elastic overlap compensation plate 9 synchronously restore their initial shape. The bidirectional conical support, clearance fit and sealing vibration reduction structure are reset, and the throat returns to its initial stable operating state, which can once again adapt to the full-condition temperature and pressure change exhaust requirements of the steam turbine 10.

[0031] The specific embodiment of the present invention has been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the embodiments described above. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and ideas of the present invention should still fall within the protection scope of the present invention.

Claims

1. A low-resistance exhaust-steam nozzle for a steam turbine, comprising a nozzle housing (1), characterized in that The throat housing (1) has multiple tapered guide holes (2) on its sidewall. Multiple rows of guide columns (3) are arranged inside the throat housing (1). The axial cross-section of each guide column (3) is streamlined. The multiple rows of guide columns (3) are staggered. Guide sleeves (4) are provided at both ends of each guide column (3). The guide column (3) penetrates the guide sleeve (4), and the guide column (3) and guide sleeve (4) are slidably connected. An annular groove (401) is provided on the sidewall of the guide sleeve (4). A metal elastic ring (5) is fitted inside the annular groove (401). The horizontal cross-section of the metal elastic ring (5) is C-shaped. Both ends of the guide column (3) are elastically supported within the tapered guide holes (2) by the metal elastic rings (5). A sliding gap (201) is provided between the hole (2) and the guide sleeve (4), the sliding gap (201) being 1-2 mm. A first conical surface (202) is provided inside the conical guide hole (2). The diameter of the conical guide hole (2) gradually decreases from the outside to the inside of the throat housing (1). The first conical surface (202) contacts the outside of the metal elastic ring (5). When the metal elastic ring (5) is deformed to fit the annular groove (401) on the inside, the diameter of the metal elastic ring (5) is greater than the small end diameter of the conical guide hole (2). A sealing cover (6) is sleeved on the outside of the conical guide hole (2). Both ends of the guide column (3) and the sealing cover (6) are provided with an axial gap (601), the axial gap (601) being 1.5-2 mm.

2. The low-resistance exhaust throat for a steam turbine according to claim 1, characterized in that, A conical block (7) is provided on the side of the conical guide hole (2) away from the throat housing (1). The conical block (7) is fixedly installed in the port of the conical guide hole (2). A second conical surface (701) is provided on the side of the conical block (7) opposite to the throat housing (1). The second conical surface (701) is opposite to the first conical surface (202), and the second conical surface (701) contacts the outer side of the metal elastic ring (5).

3. A low-resistance exhaust throat for a steam turbine according to claim 1, characterized in that, The streamlined cross section of the guide column (3) is a teardrop-shaped cross section (301). The head of the teardrop-shaped cross section (301) faces the direction of the airflow inlet, and the tail is provided with a gradually narrowing section along the airflow direction.

4. A low-resistance exhaust throat for a steam turbine according to claim 2, characterized in that, The tapered guide hole (2) is provided with a fixed slide groove (203) on the inner side, and the guide sleeve (4) is provided with a fixed slider (402) on the side wall, and the fixed slider (402) is slidably connected to the fixed slide groove (203).

5. A low-resistance exhaust throat for a steam turbine according to claim 1, characterized in that, A buffer ring (11) is provided between the annular groove (401) and the metal elastic ring (5). A sealing groove (204) is provided on the side of the sliding gap (201) in the conical guide hole (2) opposite to the metal elastic ring (5). A sealing ring (12) is provided in the sealing groove (204). A sealing gasket (8) is provided in the axial gap (601). The materials of the buffer ring (11), the sealing ring (12) and the sealing gasket (8) are all fluororubber.

6. A low-resistance exhaust throat for a steam turbine according to claim 3, characterized in that, The surface of the guide column (3) is provided with a guide groove (302) along the airflow direction, and the depth of the guide groove (302) is 0.2 to 0.5 mm.

7. A low-resistance exhaust throat for a steam turbine according to claim 1, characterized in that, The metal elastic ring (5) has a C-shaped opening with a plug-in interface (501). The plug-in interface (501) has an elastic overlap compensation piece (9) inside. One end of the elastic overlap compensation piece (9) has a plug-in section (901) which is slidably connected inside the plug-in interface (501).

8. A low-resistance exhaust throat for a steam turbine according to claim 3, characterized in that, The guide column (3) has a vibration-absorbing hole (303) in the radial center. The vibration-absorbing hole (303) penetrates the entire guide column (3) and is filled with vibration-absorbing material.

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