Dehumidification structure capable of automatically adjusting suction flow

Abstract

The invention discloses a dehumidification structure capable of automatically adjusting suction flow, and belongs to the technical field of steam turbines. The structure comprises a hollow stationary blade, an air cylinder inner wall, a combined suction cavity and a movable inner wall, stationary blade surface dehumidification seams and air cylinder inner wall water catching grooves share the combined suction cavity and a negative pressure source through evenly-arranged suction holes, and a combined dehumidification system for stationary blade surface water film catching and wall face water drop collecting is formed. The movable inner wall senses the steam pressure change through the pressure cavities on the two sides, the minimum opening degree of the water catching groove is maintained under the rated working condition, the opening degree is automatically increased under the small-flow working condition so as to improve the suction flow, and the dehumidification efficiency is enhanced and the last-stage blast loss is reduced synchronously. The device does not need an additional power source, adapts to different working conditions through a self-adjusting mechanism, has the advantages of being simple in structure, low in cost and high in working condition adaptability, effectively solves the problems of water erosion and efficiency of a steam turbine in a wet steam environment, and is suitable for turbine equipment such as thermal power equipment and nuclear power equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of steam turbines, and particularly relates to a dehumidification structure capable of automatically adjusting the suction flow rate, which is applicable to turbine equipment operating in a wet steam environment such as thermal power, nuclear power, nuclear-powered naval steam turbines, and geothermal power station steam turbines. Background Art

[0002] As the core thermal prime mover in the fields of energy, power, and power engineering, the steam turbine faces severe challenges when operating in a wet steam environment. The last few stages of thermal power plant steam turbines, nuclear power plant steam turbines, nuclear-powered naval steam turbines, and all or most stages of geothermal power station steam turbines operate in a wet steam state. The influence of wet steam on the turbine is mainly reflected in two aspects: Firstly, the non-equilibrium two-phase flow during the steam condensation process will generate wet steam losses. According to research, 1% humidity approximately leads to 1% efficiency loss, seriously affecting the economy of the steam turbine; Secondly, the primary water droplets formed by the condensation of wet steam and the secondary water droplets generated by the tearing of the water film on the blade surface will cause erosion and impact on the blade, leading to the problem of water erosion. In severe cases, it may cause the blade to break, threatening the safe and stable operation of the steam turbine.

[0003] To solve the problems brought by wet steam, the internal dehumidification technology has become the main means of steam turbine dehumidification due to its advantages of not requiring additional external equipment, simple structure, and strong operability. During the Soviet era, the dehumidification structure of the suction slot proposed by the Bryansk Institute of Machine Building could effectively capture the moisture in the wet steam by opening a slot on the inner arc surface of the stator blade not far from the outlet edge. As one of the earliest applied dehumidification technologies, the outer edge separation method uses the centrifugal effect generated by the high-speed rotation of the blade to throw the water droplets towards the outer edge catch tank and discharge them, and is widely used in the low-pressure stage of the steam turbine.

[0004] However, with the continuous improvement of the requirements for the safety and economy of steam turbines, a single dehumidification measure is difficult to meet the dehumidification requirements under complex working conditions. For example, relying solely on stator blade suction or wall suction, the dehumidification efficiency is limited and it is impossible to effectively control the steam humidity; if multiple independent dehumidification measures are adopted simultaneously, although the dehumidification effect can be improved, the equipment cost and structural complexity will increase significantly. In addition, the peak shaving task of thermal power steam turbines is becoming increasingly arduous. Under small flow conditions, backflow is likely to occur at the tip of the moving blade, resulting in increased erosion of the blade by water droplets. The traditional dehumidification structure cannot automatically adjust the suction flow rate according to the working conditions, making it difficult to provide sufficient dehumidification capacity at small flow rates, and at the same time, it may also increase the last-stage blowing loss due to insufficient suction flow rate.

[0005] In the prior art, although a few combined dehumidification structures have attempted to combine stationary blades and wall suction, most of them use independent suction pipelines and negative pressure sources, resulting in high manufacturing costs and complex systems. For the adjustment of the suction flow rate under changing operating conditions, there is a lack of an effective automatic control mechanism, and it is impossible to balance the dehumidification efficiency and economy under different operating conditions. Therefore, there is an urgent need for a combined dehumidification structure that can integrate the functions of stationary blades and the inner wall of the cylinder, share the suction pipeline and negative pressure source, and automatically adjust the suction flow rate according to the operating conditions, so as to improve the dehumidification performance on the premise of reducing costs and meet the requirements of modern steam turbines for efficient and safe operation. Summary of the Invention

[0006] The present invention aims to overcome the above-mentioned shortcomings of the prior art and provides a dehumidification structure capable of automatically adjusting the suction flow rate.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A dehumidification structure capable of automatically adjusting the suction flow rate, comprising:

[0009] A stationary blade, which is a hollow blade with dehumidification slits on its surface, and its inner cavity is connected to the combined suction cavity through stationary blade suction holes;

[0010] The inner wall of the cylinder, on the inner side of which there is a water-catching cavity, the water-catching cavity is connected to the combined suction cavity through water-catching cavity suction holes arranged uniformly along the circumference, and is connected to the main flow channel of the steam turbine through a water-catching groove;

[0011] The combined suction cavity is connected to the condenser through a combined suction pipeline to form a shared negative pressure suction system;

[0012] A movable inner wall is arranged on the inner wall of the cylinder. The movable inner wall is connected to the main flow channel of the steam turbine through a pressure cavity and can move axially under the action of steam pressure under different operating conditions to adjust the width of the water-catching groove.

[0013] Further, the movable inner wall is arranged in an L shape, and the pressure cavities are respectively arranged on the same side of the upper and lower parts of the L shape. Balance holes respectively introduce the steam pressure in the corresponding areas in the main flow channel of the steam turbine into the pressure cavities, and drive the movable inner wall to move through the pressure difference between the water-catching cavity and the pressure cavity.

[0014] Further, the water-catching cavity suction holes are arranged uniformly along the circumferential direction, and the number is 10 - 50 to achieve uniform distribution of the suction pressure in the water-catching cavity.

[0015] Further, the combined suction pipeline is arranged at the bottom of the lower half cylinder of the cylinder, and the number is 1 - 5. The combined suction cavity has a volume larger than the total volume of the water-catching cavity and the inner cavity of the stationary blade to form a stable negative pressure environment.

[0016] Further, the movement range of the movable inner wall is limited by a limiting block, which is arranged on the inner wall of the cylinder and used to limit its minimum opening degree.

[0017] Further, the inner wall of the cylinder and the movable inner wall are provided with diversion grooves at the water capture tank, which are used to guide the deposited water to be discharged through the hydrophobic system.

[0018] Further, the static blade dehumidification slot is arranged on the inner arc surface of the static blade.

[0019] Further, the water capture tank is arranged in the area of the inner wall of the cylinder between the static blade and the moving blade, and its width changes with the movement of the movable inner wall.

[0020] Further, a hydrophobic hole is arranged at the bottom of the inner cavity of the static blade, and the hydrophobic hole is communicated with the combined suction cavity to discharge the water deposited in the static blade.

[0021] Further, under the rated working condition, the left side pressure acting on the movable inner wall is greater than the right side pressure, and it moves to the right to contact the inner wall of the cylinder, so that the water capture tank maintains the maximum opening degree; under the small flow working condition, the right side pressure is greater than the left side pressure, and it moves to the left to the limiting block, so that the water capture tank maintains the minimum opening degree, realizing the automatic adjustment of the suction flow rate.

[0022] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0023] Through the combined suction of the static blade and the inner wall of the cylinder and the adaptive adjustment technology, the present invention significantly improves the dehumidification performance and operation economy of the wet steam stage of the steam turbine:

[0024] Combined suction structure: The inner cavity of the static blade and the water capture cavity of the inner wall of the cylinder share a negative pressure source and a suction pipeline through the combined suction cavity. While strengthening the double dehumidification effects of capturing the water film on the surface of the static blade and collecting the water droplets at the top of the moving blade, the arrangement of the independent suction system is reduced, and the manufacturing cost is reduced compared with the traditional composite dehumidification structure.

[0025] Working condition adaptive adjustment: The movable inner wall responds to the steam pressure change in real time through the pressure chambers on both sides. Under the rated working condition, it maintains the minimum opening degree of the water capture tank to avoid excessive suction. Under the small flow peak shaving working condition, it automatically increases the opening degree, so that the suction flow rate is increased, the dehumidification efficiency is significantly enhanced, and at the same time, the last stage blowing loss is effectively reduced by increasing the suction steam volume, solving the problem of aggravated water erosion of the traditional fixed structure under low load.

[0026] Simple and efficient structure: The self-adjusting mechanism and modular design without an additional power source are compatible with the existing steam turbine structure, and have wide applicability in the fields of thermal power, nuclear power, etc., providing an innovative solution for the safe and economic operation of turbine equipment in a wet steam environment. Description of the Drawings

[0027] Figure 1It is the overall meridional plane schematic diagram of the single-stage dehumidification structure of the turbine in the present invention.

[0028] Figure 2 It is the partial meridional plane schematic diagram of the minimum opening of the turbine dehumidification structure in the present invention.

[0029] Figure 3 It is the partial meridional plane schematic diagram of the maximum opening of the turbine dehumidification structure in the present invention.

[0030] Figure 4 It is the schematic diagram of the three-dimensional model of the turbine dehumidification structure in the present invention.

[0031] Figure 5 It is the schematic diagram of the movable inner wall structure in the present invention.

[0032] Markings in the figure:

[0033] 1 - stator blade; 2 - rotor blade; 3 - dehumidification slot; 4 - stator blade suction hole; 5 - combined suction cavity; 6 - combined suction pipeline; 7 - water-catching cavity suction hole; 8 - water-catching cavity; 9 - pressure cavity A; 10 - balance hole A; 11 - pressure cavity B; 12 - balance hole B; 13 - water-catching groove; 14 - movable inner wall; 15 - limit block; 16 - cylinder inner wall; 17 - diversion groove A; 18 - diversion groove B; 19 - drain hole A; 20 - drain hole B. Specific embodiments

[0034] The present invention will be described in detail below with reference to the accompanying drawings.

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention 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 the present invention and are not used to limit the present invention.

[0036] In this embodiment, as Figure 1 shown in Fig. -4, a dehumidification structure capable of automatically adjusting the suction flow rate includes:

[0037] Stator blades, which are hollow blades with dehumidification slots on their surfaces, and their inner cavities are connected to the combined suction cavity through stator blade suction holes;

[0038] Cylinder inner wall, with a water-catching cavity arranged on its inner side. The water-catching cavity is connected to the combined suction cavity through water-catching cavity suction holes arranged evenly along the circumference, and is connected to the main flow channel of the steam turbine through a water-catching groove;

[0039] The combined suction cavity is connected to the condenser through a combined suction pipeline to form a shared negative pressure suction system;

[0040] A movable inner wall is arranged on the inner wall of the cylinder. The movable inner wall is communicated with the main flow channel of the steam turbine through a pressure chamber and can move axially under the action of steam pressures in different working conditions to adjust the width of the water capture groove.

[0041] Specifically: the stationary blade is a hollow blade, and dehumidifying slits penetrating the blade wall surface are formed on the inner arc surface. The downstream of the dehumidifying slits is communicated with the inner cavity of the stationary blade; the inner cavity of the stationary blade is communicated with an annular combined suction chamber through a plurality of stationary blade suction holes, and the combined suction chamber is arranged around the inner wall of the cylinder.

[0042] An annular water capture chamber is arranged on the inner side of the inner wall of the cylinder. The water capture chamber is communicated with the combined suction chamber through water capture chamber suction holes uniformly distributed along the circumference; a water capture groove is formed on one side of the water capture chamber close to the gap between the stationary blade and the moving blade, and the water capture groove is directly communicated with the main flow channel of the steam turbine.

[0043] The combined suction chamber is connected with a condenser through a combined suction pipe at the bottom to form a negative pressure source; the movable inner wall is sleeved on the inner side of the inner wall of the cylinder and forms a sliding fit with the inner wall of the cylinder, and its axial movement direction is consistent with the water capture groove width adjustment direction.

[0044] When the steam turbine operates, the combined suction chamber forms a negative pressure due to being communicated with the condenser. The wet steam on the surface of the stationary blade carries water droplets and enters the inner cavity of the stationary blade through the dehumidifying slits, and converges into the combined suction chamber through the stationary blade suction holes; meanwhile, the wet steam and water droplets near the top of the moving blade enter the water capture chamber through the water capture groove and are sucked into the combined suction chamber through the water capture chamber suction holes, and finally are discharged into the condenser through the combined suction pipe.

[0045] Both sides of the movable inner wall bear the main flow pressure of the steam turbine and the negative pressure in the water capture chamber respectively. The pressure difference under different working conditions drives its axial movement: under the rated working condition, the main flow pressure is relatively high, pushing the movable inner wall to narrow the width of the water capture groove; under the small flow working condition, the main flow pressure decreases, and the negative pressure in the water capture chamber is relatively higher, pulling the movable inner wall to widen the width of the water capture groove.

[0046] The stationary blade and the inner wall of the cylinder share the same negative pressure source through the combined suction chamber and the suction pipe, reducing the layout of an independent suction system and lowering the manufacturing cost; the combined suction of the two can capture the water film on the surface of the stationary blade and the water droplets near the top of the moving blade at the same time, improving the dehumidification efficiency; the movable inner wall automatically adjusts the width of the water capture groove through the steam pressure, enabling the suction flow rate to adapt to the change of the working condition, and solving the problem of insufficient dehumidification of a single structure under small flow rates.

[0047] Further, as Figure 5 shown, the movable inner wall is arranged in an L shape, and the pressure chambers are respectively arranged on the same side of the upper part and the lower part of the L shape. Balance holes respectively introduce the steam pressures in the corresponding areas in the main flow channel of the steam turbine into the pressure chambers, and drive the movable inner wall to move through the pressure difference between the water capture chamber and the pressure chambers.

[0048] The movable inner wall is designed in an L-shaped structure. Its horizontal section fits the inner wall of the cylinder and slides axially, while the vertical section faces the reverse direction of the mainstream channel of the steam turbine. Pressure chambers are respectively arranged on both sides of the horizontal section. The upper pressure chamber A is connected to the mainstream area at the outlet of the stationary blade through the balance hole A, and the lower pressure chamber B is connected to the mainstream area at the inlet of the moving blade through another balance hole B.

[0049] Under the rated working condition, the pressure at the outlet of the stationary blade (upper pressure chamber) and the pressure at the inlet of the moving blade (lower pressure chamber) are both higher than the negative pressure in the water capture chamber. The pressure difference on both sides of the movable inner wall is to the left, pushing it to move left to the minimum opening of the water capture groove. Under the small flow condition, there is a backflow at the top of the moving blade, the pressure at the inlet of the moving blade decreases, the pressure in the lower pressure chamber is lower than the negative pressure in the water capture chamber, and the pressure difference is to the right, pulling the movable inner wall to move right to the maximum opening of the water capture groove.

[0050] The L-shaped structure enables the pressure chambers to respectively receive the mainstream pressures at the outlet of the stationary blade and the inlet of the moving blade, and transfers the working condition pressure changes in real time through the balance holes, ensuring the sensitive response of the movable inner wall to the steam pressure fluctuations. The design driven by the pressure difference on both sides does not require an additional power source, and realizes automatic adjustment by using the flow field characteristics of the steam turbine itself. The structure is simple and reliable, improving the adaptability to working conditions.

[0051] Furthermore, the suction holes in the water capture chamber are evenly arranged along the circumferential direction, and the number is 10 - 50 to achieve uniform distribution of the suction pressure in the water capture chamber.

[0052] Specifically: The suction holes in the water capture chamber are evenly arranged along the circumference of the inner wall of the cylinder, and the number is 20 - 30 (preferably 24). Each suction hole is equally spaced and has the same aperture. One end of the suction hole is connected to the inside of the water capture chamber, and the other end radially penetrates the inner wall of the cylinder and is connected to the combined suction chamber.

[0053] The evenly distributed suction holes enable the steam in each area of the water capture chamber to be synchronously sucked into the combined suction chamber under the action of negative pressure, avoiding uneven flow fields caused by too strong or too weak local suction. The symmetric arrangement in the circumferential direction ensures the same circumferential pressure in the water capture chamber, forming a stable annular suction effect.

[0054] The evenly arranged suction holes eliminate the pressure gradient in the water capture chamber, enabling the wet steam and water droplets within the entire circumference of the inner wall of the cylinder to be evenly captured, and avoiding water droplets from escaping to the top of the moving blade due to insufficient local suction. The stable suction flow field improves the reliability of the wall water capture structure and further reduces the risk of water erosion of the moving blade.

[0055] Furthermore, the combined suction pipelines are arranged at the bottom of the lower half of the cylinder, and the number is 1 - 5. The combined suction chamber has a volume larger than the total volume of the water capture chamber and the inner cavity of the stationary blade to form a stable negative pressure environment.

[0056] The combined suction pipeline is arranged at the bottom of the lower half of the cylinder, with a quantity of 3 (preferably an odd number and symmetrically distributed), and the pipeline diameter is designed according to the suction flow demand; the combined suction cavity is an annular cavity, whose volume is larger than the sum of the volumes of the inner cavity of the stationary blade and the water-catching cavity, and the inner wall is smooth to reduce the flow resistance.

[0057] The combined suction cavity stores a stable negative pressure through a large-volume design, avoiding sudden pressure changes caused by fluctuations in the suction flow; the pipelines at the bottom of the lower half of the cylinder utilize the action of gravity to automatically collect the water deposited in the inner cavity of the stationary blade and the water-catching cavity into the pipelines, and discharge it into the condenser together with the steam.

[0058] The large-volume combined suction cavity provides a stable negative pressure environment for the suction of the stationary blade and the inner wall of the cylinder, ensuring balanced suction power under different working conditions; the pipelines arranged in the lower half of the cylinder facilitate drainage, preventing water from staying at the bottom of the cavity, and improving the reliability of the dehumidification system; it reduces the problem of reduced suction efficiency caused by negative pressure fluctuations, and is especially suitable for the flow changes under peak shaving working conditions.

[0059] Furthermore, the moving range of the movable inner wall is limited by a limit block, and the limit block is arranged on the inner wall of the cylinder to limit its minimum opening degree.

[0060] The limit block is a boss structure and is arranged on the inner wall of the cylinder; the limit block is fixed at the left end of the inner wall of the cylinder in the axial direction, and when they are in contact, the minimum opening degree of the water-catching groove is limited.

[0061] The movable inner wall moves axially under the action of the pressure difference, and the limit block prevents it from moving too far to the left and causing the water-catching groove to close; the position of the limit block is preset according to the design working conditions of the steam turbine to ensure that the opening degree adjustment is within a safe range.

[0062] The limit structure avoids the out-of-control movement of the movable inner wall caused by pressure fluctuations, ensuring the safety of the dehumidification structure under extreme working conditions; the clear opening degree limit makes the adjustment of the width of the water-catching groove predictable, facilitating the matching with the steam turbine control system and improving the overall operation stability.

[0063] Furthermore, the inner wall of the cylinder and the movable inner wall are provided with diversion grooves at the water-catching groove for guiding the deposited water to be discharged through the drainage system.

[0064] The inner wall of the cylinder and the movable inner wall are respectively provided with inclined diversion groove A and diversion groove B at the water-catching groove, and the angle between the diversion groove and the horizontal plane is 15° - 30°.

[0065] The water droplets deposited on the inner wall of the cylinder flow towards the water-catching groove along the diversion groove under the action of gravity, and the inclined design guides the water flow direction, preventing the water droplets from re-entering the main flow channel due to the centrifugal force of the steam turbine rotation or the disturbance of the steam flow; the surface of the diversion groove is smooth, reducing the water flow resistance and ensuring smooth drainage.

[0066] The cooperation between the diversion groove and the water capture groove prevents water droplets on the inner wall of the cylinder (especially the upper half of the cylinder) from dripping onto the top of the moving blade, avoiding secondary water erosion; this design improves the hydrophobic efficiency of the dehumidification structure, ensuring that the captured moisture is effectively discharged instead of being re-mixed into the steam flow.

[0067] Furthermore, the dehumidification slot of the stationary blade is arranged on the inner arc surface of the stationary blade.

[0068] The arrangement of the dehumidification slots on the inner arc surface conforms to the water film flow characteristics, capable of efficiently capturing the condensed water on the surface of the stationary blade and reducing the amount of secondary water droplets shedding from the trailing edge; it forms a hierarchical dehumidification with the downstream water capture groove, improving the capture ability for water droplets of different particle sizes and reducing the risk of moving blade water erosion from the source.

[0069] Furthermore, the water capture groove is arranged in the area of the inner wall of the cylinder between the stationary blade and the moving blade, and its width changes with the movement of the movable inner wall.

[0070] The width of the water capture groove is dynamically adjusted according to the working conditions, balancing the dehumidification efficiency and the utilization of steam energy: under the rated working conditions, it avoids the efficiency reduction caused by excessive suction, and under small flow conditions, it increases the opening to improve the dehumidification ability and reduce the blowing loss, achieving the unity of economy and safety.

[0071] Furthermore, drain holes are provided at the bottom of the inner cavity of the stationary blade. The drain holes are connected to the combined suction cavity and are used to discharge the water deposited in the inner cavity of the stationary blade.

[0072] Multiple drain holes are opened at the bottom of the inner cavity of the stationary blade, evenly distributed in the root area of the blade; one end of the drain hole is connected to the inner cavity of the stationary blade, and the other end directly drains into the bottom of the combined suction cavity.

[0073] The water deposited in the inner cavity of the stationary blade gathers towards the bottom under the action of gravity and is directly discharged into the combined suction cavity through the drain holes, avoiding the internal corrosion of the stationary blade or the increase of flow resistance caused by water retention; the arrangement of the drain holes forms a complement with the suction holes of the stationary blade to ensure the dryness of the inner cavity.

[0074] The drain hole design solves the problem of water accumulation inside the hollow stationary blade, prevents the erosion of the stationary blade structure by water during long-term operation, and extends the blade life; at the same time, it avoids the influence of water accumulation on the suction flow field and ensures the continuous and efficient operation of the dehumidification slots of the stationary blade.

[0075] Furthermore, under the rated working conditions, the pressure on the left side of the movable inner wall is greater than that on the right side, and it moves to the right to contact the inner wall of the cylinder, making the water capture groove maintain the maximum opening; under small flow working conditions, the pressure on the right side is greater than that on the left side, and it moves to the left to the limit block, making the water capture groove maintain the minimum opening, realizing the automatic adjustment of the suction flow rate.

[0076] The left side of the movable inner wall is connected to the main flow channel of the steam turbine (the stator vane outlet area), and the right side is connected to the water capture chamber. Under rated conditions, the main flow pressure (left side) is greater than the negative pressure in the water capture chamber (right side), and the resultant pressure is to the left, pushing the movable inner wall to move left to the limit block, and the water capture groove maintains the minimum opening. Under low-flow conditions, the main flow pressure drops, and the negative pressure in the water capture chamber is relatively higher. The resultant pressure is to the right, pulling the movable inner wall to move right until it contacts the cylinder inner wall, and the water capture groove maintains the maximum opening.

[0077] The pressure chamber transmits the main flow pressure in real time through the balance hole, and the movable inner wall automatically responds to the change of working conditions: restricting suction at high flow rates to ensure efficiency, and increasing suction at low flow rates to enhance dehumidification.

[0078] The self-regulating mechanism based on the pressure difference does not require external control and can adapt to the load change of the steam turbine in real time. Especially under the peak-shaving low-flow conditions, by increasing the width of the water capture groove, the suction flow rate is significantly increased, effectively reducing the water droplet deposition at the blade tip of the moving blade caused by backflow, reducing the risk of water erosion. At the same time, by increasing the suction steam volume, the last-stage windage loss is reduced, achieving a double optimization of working condition adaptability and economy.

[0079] The above are only the preferred embodiments of the invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An automatically adjustable suction flow dehumidification structure, characterized in that, Comprising: A stationary blade, which is a hollow blade with dehumidification slits formed on its surface, and its inner cavity is communicated with a combined suction cavity through stationary blade suction holes; The inner wall of the cylinder, on the inner side of which there is a water capture cavity, the water capture cavity is communicated with the combined suction cavity through water capture cavity suction holes uniformly arranged along the circumference, and is communicated with the main steam passage of the steam turbine through a water capture groove; The combined suction cavity is connected to a condenser through a combined suction pipeline to form a shared negative pressure suction system; A movable inner wall is arranged on the inner wall of the cylinder, the movable inner wall is communicated with the main steam passage of the steam turbine through a pressure cavity, and can move axially under the action of steam pressure under different working conditions to adjust the width of the water capture groove; 2. The automatically adjustable suction flow dehumidification structure according to claim 1, wherein, The movable inner wall is arranged in an L shape, the pressure cavities are respectively arranged on the same side of the upper and lower parts of the L shape, balance holes respectively introduce the steam pressure in the corresponding areas in the main steam passage of the steam turbine into the pressure cavities, and the movable inner wall is driven to move through the pressure difference between the water capture cavity and the pressure cavity; 3. The automatic suction flow adjustable dehumidification structure according to claim 1, characterized in that, The water capture cavity suction holes are uniformly arranged along the circumferential direction, and the number is 10 - 50 to achieve uniform distribution of the suction pressure in the water capture cavity; 4. The dehumidification structure with an automatically adjustable suction flow rate according to claim 1, characterized in that, The combined suction pipelines are arranged at the bottom of the lower half cylinder of the cylinder, and the number is 1 - 5. The combined suction cavity has a volume larger than the total volume of the water capture cavity and the inner cavity of the stationary blade to form a stable negative pressure environment; 5. The dehumidification structure with an automatically adjustable suction flow rate according to claim 1, wherein, The movement range of the movable inner wall is limited by a limit block, and the limit block is arranged on the inner wall of the cylinder to limit its minimum opening; 6. The dehumidification structure with an automatically adjustable suction flow rate according to claim 1, characterized in that The inner wall of the cylinder and the movable inner wall are provided with diversion grooves at the water capture groove for guiding the deposited water to be discharged through a drainage system; 7. An automatically adjustable suction flow dehumidification structure according to claim 1, characterized in that, The dehumidification slits of the stationary blade are arranged on the inner arc surface of the stationary blade; 8. A dehumidification structure with an automatically adjustable suction flow rate according to claim 1, characterized in that, The water capture groove is arranged in the area of the inner wall of the cylinder between the stationary blade and the moving blade, and its width changes with the movement of the movable inner wall; 9. The automatic suction flow adjustable dehumidification structure according to claim 1, characterized in that, A drainage hole is arranged at the bottom of the inner cavity of the stationary blade, and the drainage hole is communicated with the combined suction cavity for discharging the water deposited in the stationary blade; 10. A dehumidification structure with an automatically adjustable suction flow rate according to claim 5, characterized in that, Under the rated working condition, the pressure on the left side of the movable inner wall is greater than that on the right side, and it moves to the right to contact the inner wall of the cylinder, so that the water capture groove maintains the maximum opening; Under the small flow working condition, the pressure on the right side is greater than that on the left side, and it moves to the left to the limit block, so that the water capture groove maintains the minimum opening to realize automatic adjustment of the suction flow.

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