A steam turbine unit, thermal system, and operation method based on series auxiliary regulation.

Abstract

This invention provides a steam turbine unit, thermal system, and operation method based on series auxiliary regulation. Multiple regulating pressure stages (6) that can use full-circumference steam inlet are connected in series before the conventional pressure stage group (41). Each regulating pressure stage group (6) has a corresponding regulating steam inlet channel (10) to transport steam. Different regulating pressure stages (6) are put into operation according to different load ranges. When the regulating pressure stage group (6) located upstream is put into operation, the regulating pressure stage group (6) located downstream is also put into operation due to the series relationship, realizing the structural adaptability reconstruction of the steam turbine unit, improving the low-load efficiency of the unit, reducing the vibration amplitude, and only using the axial length space of the unit, the construction of different pressure stage structures can be realized. Under medium and low loads, the boiler flue temperature is low, which poses a risk of not meeting the denitrification requirements. By leading an extraction pipe from the end of the regulating pressure stage group and connecting it to an adjustable heater, the water temperature at the boiler inlet is increased. The flue gas temperature at the denitrification point is adjusted according to actual needs to meet the denitrification requirements.

Description

Technical Field

[0001] This invention belongs to the field of thermal conversion technology, and particularly relates to a steam turbine unit, thermal system and operation method based on series auxiliary regulation. Background Technology

[0002] Steam turbines are widely used in civilian power generation (thermal power, nuclear power, biomass power, etc.) and large civilian transport vessels, as well as in military transport applications such as aircraft carriers, large ships, and nuclear submarines, making them one of the most important large-scale power equipment. Low-load operation of steam turbines not only leads to a significant increase in unit energy consumption, but also, under conventional sequential valve steam distribution, can cause severe unit vibration due to uneven circumferential steam intake, affecting safe operation and even impacting the radar protection capabilities of military vessels.

[0003] The "dual-carbon" strategy promotes the construction of a new power system with new energy sources as the mainstay. With the grid connection of large-scale photovoltaic, wind power, and other new energy power sources with random fluctuations, the basic power system, mainly thermal power, is forced to fully participate in deep peak shaving. Thermal power unit design mainly considers the operating efficiency under rated load conditions. During deep peak shaving, the power generation efficiency of units under medium and low load conditions deteriorates sharply. Compared with rated load conditions, the coal consumption of conventional thermal power units at 30% rated load conditions increases by 30-40 g / kW·h. This greatly reduces the overall energy conservation and emission reduction benefits for the whole society generated by making way for new energy sources.

[0004] Based on the existing technical and structural characteristics of steam turbines and thermal systems, under low-load conditions, regardless of whether the main steam pressure operates in sliding pressure, constant pressure, or "constant-sliding-constant" mode, the pressures after the regulating stage drop significantly. Furthermore, under medium- and low-load conditions, the large ideal enthalpy drop between the rated main steam pressure provided by the boiler and the pressure after the regulating stage cannot be effectively utilized by existing technologies. This directly leads to a significant decrease in the cycle efficiency of the thermal system and a substantial increase in system energy consumption under medium- and low-load conditions.

[0005] Solving the problem of decreased operating efficiency of steam turbine units under low-load conditions during deep peak shaving is a crucial issue concerning energy conservation and emission reduction for civilian enterprises, overall energy conservation and emission reduction, and even the timely and high-quality achievement of the national "dual carbon" targets. It is also a fundamental issue concerning the single-voyage range and overall service capability of transport equipment. Vibration issues under low-load conditions are a core issue concerning the safe operation of equipment and safe navigation for military purposes. Therefore, there is an urgent need for a steam turbine unit and thermal system that can maintain high cycle efficiency and controllable vibration performance under medium and low load conditions to solve the current problems. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a full-load high-efficiency steam turbine unit, thermal system and operation method, which is mainly used to solve the problems of low operating efficiency, poor regulation capability and large vibration of coal-fired power units under medium and low loads when participating in deep peak shaving.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides a steam turbine unit based on series auxiliary regulation, comprising a power cylinder body, wherein the power cylinder body is any one of a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder, wherein the power cylinder body is provided with a conventional steam inlet passage and a conventional pressure stage group, and wherein the power cylinder body is also provided with at least one regulating pressure stage group, wherein the regulating pressure stage group is coaxially connected in series before the conventional pressure stage group, wherein each regulating pressure stage group is provided with at least one pressure stage, wherein the pressure stage is composed of a stationary blade plate at the front end and a moving blade plate at the rear end, wherein each regulating pressure stage group corresponds to an independent regulating steam inlet passage, and wherein at least one regulating valve for controlling the on / off of steam flow is connected to the front end of the regulating steam inlet passage.

[0009] Furthermore, the conventional pressure stage group or at least one of the regulating pressure stage groups adopts a full-circumferential steam inlet method, and no regulating stage is set at its front end.

[0010] Furthermore, the stationary vane in the foremost pressure stage of the regulating pressure stage group, which is furthest from the conventional pressure stage group, is embedded in the inner cylinder of the working cylinder.

[0011] Furthermore, the regulating pressure stage group furthest from the conventional pressure stage group is provided with an regulating stage, and the regulating stage is provided with at least two nozzle groups.

[0012] Furthermore, each of the regulating pressure stage groups is provided with a corresponding check valve assembly at its outlet. The check valve assembly is used to open when the corresponding regulating pressure stage group and the regulating pressure stage groups preceding it are in operation, and to close when the corresponding regulating pressure stage group is not in operation and the regulating pressure stage group or the conventional pressure stage group following it is in operation.

[0013] Furthermore, each of the pressure regulating stages has an annular channel at its outlet, and the check valve assembly is located at the annular channel.

[0014] Furthermore, the anti-reverse gate assembly includes multiple anti-reverse gate units arranged sequentially along the circumferential direction. Each anti-reverse gate unit includes a rotating shaft and an opening / closing component. The opening / closing component can rotate along the rotating shaft. In the closed state, the axial projection of the opening / closing component is an irregular surface composed of an inner edge line, a first side line, a second side line, and an outer edge line. The irregular surfaces do not overlap. In the closed state, the circle formed by the inner edges of the multiple opening / closing components connected end to end coincides with the inner circle of the annular channel. The outer edges of the multiple opening / closing components connected end to end form a closed shape.

[0015] Furthermore, the outer edge line is a straight line, the closed shape is a polygon, the polygon has ≥3 sides, and the central axis of the rotation axis coincides with the axial projection of the edge line of the polygon.

[0016] Furthermore, the area covered by the inscribed circle of the polygon is greater than or equal to the outer circle of the annular channel.

[0017] Furthermore, the outer edge line is an arc, the closed shape is a circle, and the coverage area of ​​the circle is greater than or equal to the outer circle of the annular channel.

[0018] Furthermore, the opening and closing member flips outward or inward along the rotation axis according to the front and rear pressure difference of the area it is in.

[0019] Furthermore, the rotation angle of the opening and closing component from the closed state to the open state is no greater than 135°.

[0020] Furthermore, the non-return door unit also includes two positioning components, which are used to fix or buffer the opening and closing components in the closed and open states, respectively.

[0021] Secondly, the present invention also provides a thermal system based on series auxiliary regulation, including a boiler and a steam turbine unit based on series auxiliary regulation as described above, wherein the working cylinder is a high-pressure cylinder, the boiler is connected to the regulating steam inlet channels one by one through a pipeline system, the pipeline system is provided with a main steam valve for controlling the on and off of the main steam flow of the boiler, and at least one regulating valve is provided between the main steam valve and each regulating steam inlet channel.

[0022] Furthermore, the pipeline system includes a main steam pipeline and at least one branch steam pipeline network. The main steam valve is located on the main steam pipeline, and the branch steam pipeline network consists of several branch steam pipelines, each of which is equipped with a regulating valve.

[0023] Furthermore, it also includes a regenerative system, which includes at least one adjustable heater, and at least one steam outlet of the regulating pressure stage group is connected to the adjustable heater via an extraction pipe, the extraction pipe being equipped with an adjusting valve assembly, and the adjustable heater being connected to the boiler.

[0024] Thirdly, the present invention also provides a method for operating a thermodynamic system based on series-assisted regulation, comprising the following steps:

[0025] Based on the distance between each regulating pressure level group and the first pressure level of the conventional pressure level group, they are defined sequentially from near to far as the first regulating pressure level group, the second regulating pressure level group, ... the nth regulating pressure level group. The regulating steam inlet channels corresponding to the regulating pressure level groups are defined sequentially as the first regulating steam inlet channel, the second regulating steam inlet channel, ... the nth regulating steam inlet channel. The conventional steam inlet channel is determined as the zeroth steam inlet channel.

[0026] The operating load of the thermal system is divided into n+1 load intervals, and each load interval is associated with one of the regulating steam inlet channels.

[0027] Based on the current operating load rate of the thermal system or the set target load rate, determine the target load range that the thermal system needs to enter, and switch to the regulating steam inlet channel corresponding to the target load range.

[0028] Furthermore, when the thermal system is increasing its load, the final regulating steam inlet channel to be switched to is determined based on the load increase rate or target load rate requirement;

[0029] Directly open the final regulating steam inlet passage, or;

[0030] If there are other intermediate regulating steam inlet channels between the final regulating steam inlet channel and the current regulating steam inlet channel, then the intermediate regulating steam inlet channels shall be opened sequentially or simultaneously starting from the current regulating steam inlet channel until the final regulating steam inlet channel is opened.

[0031] Determine if the current load has reached the set value. If it has, gradually close all regulating steam inlet channels except for the final regulating steam inlet channel.

[0032] Furthermore, when the thermal system is reducing its load, the final regulating steam inlet channel to be switched to is determined according to the required load reduction rate.

[0033] Gradually close the regulating valve corresponding to the current steam inlet channel;

[0034] Determine whether the current load has reached the set value. If it has, gradually open the regulating valve corresponding to the final regulating steam inlet channel and gradually close the regulating valve corresponding to the current regulating steam inlet channel.

[0035] Furthermore, when the load rate of the thermal system is lower than X% of the rated load, the gas regulating valve assembly is opened to input the steam in the corresponding regulating pressure stage group into the adjustable heater.

[0036] Furthermore, the boiler flue temperature is detected. If the boiler flue temperature is lower than the set temperature value, the gas regulating valve assembly is opened. By controlling the opening degree of the gas regulating valve assembly, the boiler flue temperature is adjusted to be higher than the set temperature value.

[0037] Compared with the prior art, the present invention has at least the following beneficial effects:

[0038] Multiple regulating pressure stages are connected in series before the conventional pressure stage group. Each regulating pressure stage group has a corresponding regulating steam inlet channel to transport steam. Different regulating pressure stages are put into operation according to different load ranges. When the upstream regulating pressure stage group is put into operation, the downstream regulating pressure stage group will also be put into operation due to the series connection. This realizes the structural adaptability reconstruction of the turbine unit, improves the low-load efficiency of the unit, and only requires the axial length space of the unit to build different pressure stage structures.

[0039] Since the regulating pressure stage group can fully adopt the full circumferential steam intake method, it can eliminate the problem of uneven circumferential steam intake caused by partial steam intake under low load conditions, which leads to excessive unit vibration.

[0040] The main steam valve and regulating valves installed in the pipeline system are used to control the opening and closing of each regulating steam inlet channel. In addition, by setting up a multi-level branch steam pipeline network, a smooth transition can be achieved when switching between different regulating steam inlet channels, avoiding sudden changes in steam flow and eliminating potential vibration and safety hazards under low load conditions.

[0041] Under low and medium load conditions, the boiler flue temperature is low, which poses a risk of not meeting the denitrification requirements. By leading an extraction pipe from the end of the regulating pressure stage group and connecting it to an adjustable heater, the water temperature at the boiler inlet can be increased. The flue gas temperature at the denitrification point can be adjusted according to actual needs to meet the denitrification requirements.

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0043] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0044] Figure 1 This is a half-sectional schematic diagram of a steam turbine unit based on series auxiliary regulation provided by the present invention.

[0045] Figure 2 This is a schematic diagram of the non-return valve assembly in the closed state according to an embodiment of the present invention.

[0046] Figure 3 This is a schematic diagram of the non-return valve assembly in the open state according to an embodiment of the present invention.

[0047] Figure 4 This is a schematic diagram of the non-return valve assembly in the closed state according to another embodiment of the present invention.

[0048] Figure 5 This is a schematic diagram of the non-return valve assembly in the open state according to another embodiment of the present invention.

[0049] Figure 6 This is a schematic diagram of a thermodynamic system based on series auxiliary regulation provided by the present invention.

[0050] Figure 7 This is a schematic diagram of a piping system in one implementation method.

[0051] Figure 8 This is a schematic diagram of a piping system in another implementation method. Detailed Implementation

[0052] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0054] In the description of this invention, when a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device. When a specific device is described as being connected to other devices, the specific device may be directly connected to the other devices without an intermediary device, or it may not be directly connected to the other devices but may have an intermediary device.

[0055] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0056] Firstly, referring to Figure 1 This embodiment discloses a steam turbine unit based on series auxiliary regulation, including a power cylinder 2, which is any one of a high-pressure cylinder 4, an intermediate-pressure cylinder, and a low-pressure cylinder. The power cylinder 2 is provided with a conventional steam inlet passage 42 and a conventional pressure stage group 41. However, since the operating load of the unit often changes, and the conventional pressure stage group 41 is designed according to the rated load condition, it cannot adapt to the medium and low load conditions. Therefore, this embodiment also provides at least one regulating pressure stage group 6 in the power cylinder 2. The regulating pressure stage group 6 is coaxially connected in series before the conventional pressure stage group 41. Each regulating pressure stage group 6 is provided with at least one pressure stage 7. The pressure stage 7 consists of a stator vane 8 located at the front end and a rear... The pressure stage 7 is composed of two sets of moving blades 9 at the end, and two sets of moving blades 8 are composed of multiple stationary blades arranged circumferentially. The pressure stage 7 responds to the main steam generated from the boiler 1 and performs work. Each regulating pressure stage group 6 has an independent regulating steam inlet channel 10. The front end of the regulating steam inlet channel 10 is connected to at least one regulating valve 11 for controlling the flow of steam. Along the axial direction, the pressure stages 7 of the two regulating pressure stage groups 6 are separated by the regulating steam inlet channel 10. The pressure stages of the last regulating pressure stage group and the conventional pressure stage group 41 are separated by the conventional steam inlet channel 42.

[0057] It should be noted that the working cylinder 2 in the steam turbine unit can be a high-pressure cylinder 4, an intermediate-pressure cylinder, and a low-pressure cylinder. Each of the high-pressure cylinder 4, the intermediate-pressure cylinder, and the low-pressure cylinder can be equipped with at least one pressure regulating stage group 6 connected in series. Therefore, it should be considered that no matter which one or more working cylinders 2 are equipped with a pressure regulating stage group 6, they are all within the scope of protection claimed in this embodiment, and will not be described in detail here.

[0058] Each regulating steam inlet channel 10 has a corresponding regulating valve 11 that controls the on / off flow of its steam. It should be noted that one regulating valve 11 can control one regulating steam inlet channel 10, or one regulating valve 11 can control two or more regulating steam inlet channels 10, or multiple regulating valves 11 can control one regulating steam inlet channel 10, or a combination of the above methods.

[0059] When operating under high load, the conventional steam inlet channel 42 is opened and delivers main steam, and the conventional pressure stage group 41 is put into operation. When the unit operates under medium and low load, it can switch to different regulating pressure stage groups 6 according to the specific load range. Each regulating pressure stage group 6 is connected in series along the coaxial direction of the conventional pressure stage group 41. Each regulating pressure stage group 6 is equipped with a pressure stage 7 for performing work. That is, each pressure stage 7 is connected in series along the coaxial direction, and each pressure stage 7 is in standby state. Therefore, when the upstream regulating pressure stage group 6 is put into operation, the pressure stage 7 in the downstream regulating pressure stage group 6 will also be put into operation. By activating different regulating steam inlet channels 10, the lower the unit load, the more regulating pressure stages 7 are put into operation, and the downstream pressure stages 7 can be shared. Different pressure stage 7 structures can be built by utilizing the axial length space of the stage group, realizing the structural adaptability reconstruction of the turbine unit and improving the low load efficiency of the unit.

[0060] As can be seen, each regulating pressure stage group 6 is a backup pressure stage group of the conventional pressure stage group 41. It can dynamically reconfigure the pressure stage group actually in operation in the working cylinder 2 according to the actual load. The lower the load, the more pressure stages 7 are put into operation. In this embodiment, each pressure stage 7 is arranged along the axial direction. Only the upstream regulating steam inlet channel 10 needs to be opened to utilize the downstream pressure stage 7. The pressure stage 7 has a high utilization rate, strong adaptability of the unit, and high efficiency.

[0061] In some embodiments, the conventional pressure stage group 41 or at least one regulating pressure stage group 6 adopts a full-circumferential steam inlet method, and no regulating stage is set at its front end. Furthermore, no regulating stage with partial steam inlet is set. Through the above steam inlet method, and in addition to switching to the regulating steam inlet channel 10 that allows more pressure stages 7 to be put into operation at low load, the problem of excessive unit vibration caused by uneven circumferential steam inlet due to partial steam inlet under low load conditions can be eliminated, and the vibration amplitude of the unit under low load conditions can be reduced.

[0062] In some embodiments, the various regulating pressure stage groups are arranged in series from near to far along the axial direction. Under the lowest load condition, the regulating pressure stage group 63, which is farthest from the conventional pressure stage group 41, is turned on. In order to improve the operating stability of the turbine unit under the lowest load, the stator vane of the pressure stage at the frontmost part of the farthest regulating pressure stage group 63 is embedded in the inner cylinder 26 of the power cylinder 2. Since the inner cylinder 26 is the stator, it is stationary and has high stability, thus strengthening the connection strength of the stator vane of the frontmost pressure stage 63.

[0063] In some embodiments, the regulating pressure stage group 6, which is furthest from the conventional pressure stage group 41, is provided with a regulating stage. The regulating stage is provided with at least two nozzle groups. That is, under the lowest load condition, the regulating stage needs to be added. By utilizing the function of the regulating stage, the operating efficiency is improved when all the pressure stages 7 in the regulating pressure stage group 6 are in operation.

[0064] In this embodiment, each regulating pressure stage group 6 has a corresponding check valve assembly 12 at its outlet, and each regulating pressure stage group 6 has a corresponding check valve assembly 12. The regulating pressure stage group 6 is in front, and the check valve assembly 12 is behind. The check valve assembly 12 is used to open when the corresponding regulating pressure stage group 6 and the regulating pressure stage group 6 before it are in operation, and to close when the corresponding regulating pressure stage group 6 is not in operation, and the regulating pressure stage group 6 after it or the conventional pressure stage group 41 is in operation. The above description of the front and back directions corresponds to the direction of steam flow. That is, the check valve assembly 12 is equivalent to an on / off valve. It can ensure that only a portion of the pressure stages 7 that are actually needed have steam passing through in the various pressure stages 7 connected in series along the same axis, while the other portion of the pressure stages 7 that do not need to be put into operation does not have steam passing through, and prevents this portion of the pressure stages 7 from running dry, causing a blowout phenomenon and reducing system efficiency.

[0065] More specifically, three regulating pressure stage groups 6 are set before the conventional pressure stage group 41, namely the first regulating pressure stage group 61, the second regulating pressure stage group 62, and the third regulating pressure stage group 63, from near to far. Each regulating pressure stage group 6 has two pressure stages 7, for a total of six pressure stages 7. Immediately following each regulating pressure stage group 6 is its corresponding check valve assembly 12. The regulating pressure stage group 6 and the check valve assembly 12 correspond one-to-one. For example, when the second regulating pressure stage group 62 is in operation, the second check valve assembly and the first check valve assembly will be open, and all four pressure stages in the first regulating pressure stage group 61 and the second regulating pressure stage group 62 will be in operation. However, the third check valve assembly will be closed, meaning that the two pressure stages in the third regulating pressure stage group 63 will not be in operation and will not rotate.

[0066] Furthermore, each regulating pressure stage group 6 has an annular channel 104 at its outlet. The regulating steam inlet channel 10 of the next regulating pressure stage group is distributed through this annular channel 104. The non-return valve assembly 12 is located at the annular channel 104. Utilizing the space of the annular channel 104, the non-return valve assembly 12 can both block the regulating steam inlet channel 10 of the next stage outward and block the outlet of the current regulating pressure stage group 6 inward. For example, in the previous example, the position of the third non-return valve assembly is the annular channel 104 corresponding to the regulating steam inlet channel 10 of the second regulating pressure stage group 62. When the third non-return valve assembly is closed, the steam in the regulating steam inlet channel 10 of the second regulating pressure stage group 62 can pass smoothly through the annular channel 104 and then enter the two pressure stages in the second regulating pressure stage group 62 and the two pressure stages in the first regulating pressure stage group 61 in sequence.

[0067] Reference Figures 2 to 5In this embodiment, the anti-reverse valve assembly 12 includes multiple anti-reverse valve units 13 arranged sequentially along the circumferential direction. Each anti-reverse valve unit 13 is connected end to end. Each anti-reverse valve unit 13 includes a rotating shaft 15 and an opening / closing member 14. The opening / closing member 14 can rotate along the rotating shaft 15, while the position of the rotating shaft 15 remains fixed. The opening / closing member 14 has two states: an open state and a closed state. In the closed state, the axial projection of the opening / closing member 14 is an irregular surface composed of an inner edge line 21, a first edge line 22, a second edge line 23, and an outer edge line 24. The inner edge line 21 and the outer edge line 24 are located on the inner and outer sides, respectively. The first edge line 22 and the second edge line 23 connect the left and right ends of the inner edge line 21 and the outer edge line 24, respectively. In the axial projection, the irregular surfaces corresponding to each opening and closing component 14 do not overlap. In the closed state, the circle formed by the inner edge lines 21 of multiple opening and closing components 14 coincides with the inner circle 17 of the annular channel 104. The outer edge lines 24 of multiple opening and closing components 14 form a closed shape. When multiple non-return valve units 13 are closed, the circle formed by the multiple inner edge lines 21 can abut against the inner circle 17 of the corresponding annular channel 104 to ensure sealing and effectively prevent steam from flowing to the upstream area.

[0068] Combination Figure 2 and Figure 3 In one implementation, the outer edge 24 is a straight line, the closed shape is a polygon, the number of sides of the polygon is ≥3, the central axis of the rotation axis 15 coincides with the axial projection of the edge of the polygon, and the opening and closing member 14 rotates along the rotation axis 15, which is equivalent to the irregular surface rotating along the edge of the polygon.

[0069] Preferably, the coverage area of ​​the inscribed circle of the polygon is greater than or equal to the outer circle 16 of the annular channel 104. That is, when the non-return valve assembly 12 is in the open state, after each opening and closing component 14 flips outward along the rotation axis 15, the outer circle 16 of the annular channel 104 can be completely exposed, and the flow of steam in the annular channel 104 is no longer affected by the non-return valve assembly 12, ensuring smooth flow.

[0070] Combination Figure 4 and Figure 5 In another implementation, the outer edge line 24 is an arc, and the closed shape is a circle. The outer edge lines 24 of each opening and closing component 14 are connected end to end to form a closed circle. At this time, the two endpoints of the outer edge line 24 are connected by a straight line. The virtual straight line corresponding to each opening and closing component 14 is also connected end to end to form a polygon. Furthermore, the coverage area of ​​the circle is greater than or equal to the outer circle 16 of the annular channel 104. In addition, when the opening and closing component 14 is rotated outward by 180°, that is, the outer edge line 24 is rotated inward and the inner edge line 21 is rotated outward, the coverage area of ​​the shape formed by the outer edge lines 24 also completely covers the outer circle 16 of the annular channel 104, ensuring that even in the most extreme state, it does not occupy the flow area of ​​the annular channel 104.

[0071] In this embodiment, the opening and closing component 14 flips outward or inward along the rotation axis 15 according to the pressure difference between the front and rear of the area. That is, there are no other actuators between the opening and closing component 14 and the rotation axis 15. The opening and closing of the opening and closing component 14 depends entirely on the action of steam flow. When the regulating pressure stage group 6 in front of the check valve assembly 12 is in operation, the steam flow in front opens each opening and closing component 14. When the regulating pressure stage group 6 in front of the check valve assembly 12 is not in operation, and the regulating air intake channel immediately behind it is open to allow steam to flow, the steam flow behind it closes each opening and closing component 14. The entire opening and closing process does not require specific actuators for control. It changes according to the changes in steam flow. The opening and closing process is stable and reliable and does not require control.

[0072] Preferably, the rotation angle of the opening and closing member 14 from the closed state to the open state is no more than 135°. Furthermore, the anti-reverse door unit 13 also includes two positioning members, which are used to fix or buffer the opening and closing member 14 in the closed state and the open state, respectively.

[0073] It should be noted that, due to the high speed of the steam flow, the opening and closing component 14 may be suddenly impacted whether it is open or closed. In order to eliminate the sudden impact or vibration of the opening and closing component 14, positioning components are set at the two position points of the opening and closing component 14 in the closed and open states, respectively. This serves two purposes: first, to fix the opening and closing component 14 in place, and second, to achieve a buffering effect and avoid damage to the cylinder.

[0074] Reference Figure 6 Secondly, this embodiment provides a thermal system based on series auxiliary regulation, including a boiler 1 and a steam turbine unit based on series auxiliary regulation as described in the above embodiment. The working cylinder 2 is a high-pressure cylinder 4. The boiler 1 is connected to the regulating steam inlet channels 10 one by one through a pipeline system. The pipeline system is provided with a main steam valve 5 for controlling the on / off of the main steam flow of the boiler 1. At least one regulating valve 11 is provided between the main steam valve 5 and each regulating steam inlet channel 10. The main steam valve 5 is used to control the on / off of the main steam at the outlet of the boiler 1, while the regulating valve 11 is used to control the on / off of one or more regulating steam inlet channels 10. Of course, a regulating valve 11 that can control the flow ratio can also be adopted, and the steam flow rate can be changed by controlling the opening degree of the regulating valve 11.

[0075] It should be noted that in order to achieve the operation switching between the regulating steam inlet channels 10, there are many kinds of correspondence between the regulating valve 11 and the regulating steam inlet channel 10. These correspondences are all realized by the pipeline system. More specifically, the pipeline system includes a main steam pipeline and at least one level of branch steam pipeline. The main steam valve 5 is located on the main steam pipeline, and the branch steam pipeline consists of several branch steam pipelines. Each branch steam pipeline is equipped with a regulating valve 11.

[0076] Reference Figure 7 As one implementation method, a one-to-many approach is adopted, with one main steam pipeline paired with a primary branch steam pipeline network. The number of branch steam pipelines is equal to the number of regulating steam inlet channels 10. One regulating valve 11 directly controls one regulating steam inlet channel 10. There is only one regulating valve 11 between the regulating steam inlet channel 10 and the main steam valve 5.

[0077] Reference Figure 8 As another implementation method, a "one-to-many" approach is adopted, with one main steam pipeline connected to two levels of branch steam networks. That is, the main steam pipeline is directly connected to the first-level branch steam network, and the first-level branch steam network is then directly connected to the second-level branch steam network. In an embodiment with three regulating steam inlet channels 10, the first-level branch steam network has two branch steam pipelines, and the second-level branch steam network has three branch steam pipelines. Each branch steam pipeline in the first-level branch steam network is simultaneously connected to the branch steam pipelines of two second-level branch steam networks. The advantage of this arrangement is that when it is necessary to switch regulation across regulating steam inlet channels 10, the intermediate regulating steam inlet channel 10 can play a transitional role, providing a transitional phase.

[0078] Additionally, if the working cylinder 2 is a medium-pressure cylinder, at least one pressure regulating stage group 6 is installed in the medium-pressure cylinder. This pressure regulating stage group 6 is connected to the reheated pipeline in the boiler 1. Similarly, the connection relationship between the reheated pipeline and the pressure regulating stage group 6 of the medium-pressure cylinder can refer to the connection relationship between the main steam pipeline of the boiler 1 and the pressure regulating stage group 6 of the high-pressure cylinder 4. The same applies if the working cylinder 2 is a low-pressure cylinder. These details will not be elaborated here.

[0079] Reference Figure 6In some embodiments, a regeneration system 3 is also included. The regeneration system 3 includes an adjustable heater 19. The end of the regulating pressure stage group 6 is connected to the adjustable heater 19 via an extraction pipe. Typically, the extraction pipe is connected at the annular channel 104 after the pressure stage 7 of the regulating pressure stage group 6, which is closest to the conventional pressure stage group 41. An air regulating valve assembly 18 is provided on the extraction pipe, which can adjust the opening and closing of the extraction pipe and its flow rate. The adjustable heater 19 is connected to the boiler 1. The purpose of this is that when the boiler 1 is under medium and low load, the flue gas temperature is low, which may not meet the denitrification requirements. By leading an extraction pipe from the end of the regulating pressure stage group 6 to the adjustable heater 19, the water temperature at the inlet of the boiler 1 is increased, and the flue gas temperature at the denitrification point is adjusted according to actual needs to meet the denitrification requirements.

[0080] Thirdly, this embodiment provides a method for operating a thermodynamic system based on series auxiliary regulation, including the following steps:

[0081] S1: Based on the distance between each regulating pressure stage group 6 and the first pressure stage 7 of the conventional pressure stage group 41, they are defined from near to far as first regulating pressure stage group 61, second regulating pressure stage group 62... nth regulating pressure stage group 6, and the regulating steam inlet channel 10 corresponding to the regulating pressure stage group 6 is defined as first regulating steam inlet channel 101, second regulating steam inlet channel 102... nth regulating steam inlet channel 10, and the conventional steam inlet channel 42 is determined as the zeroth steam inlet channel;

[0082] S2: Divide the operating load of the thermal system into n+1 load intervals, and associate each load interval with a regulating steam inlet channel 10;

[0083] In this embodiment, n=3, meaning there are 3 regulating steam inlet channels 10 arranged sequentially from near to far. The conventional steam inlet channel 42, or zeroth steam inlet channel, immediately follows the conventional pressure stage group 41. A total of 4 load intervals are defined: [100%, 90%], [90%, 70%], [70%, 50%], and [50%, 30%]. The [100%, 90%] load interval corresponds to only the zeroth steam inlet channel being activated, with only the conventional pressure stage group 41 in operation. The [90%, 70%] load interval corresponds to... Only the first regulating steam inlet channel 101 is opened, and the first regulating pressure stage group 61 and the conventional pressure stage group 41 are put into operation; for the [70%, 50%] load range, only the second regulating steam inlet channel 102 is opened, and the second regulating pressure stage group 62, the first regulating pressure stage group 61 and the conventional pressure stage group 41 are put into operation; for the [50%, 30%] load range, only the third regulating steam inlet channel 103 is opened, and the third regulating pressure stage group 63, the second regulating pressure stage group 62, the first regulating pressure stage group 61 and the conventional pressure stage group 41 are all put into operation.

[0084] S3: Based on the current operating load rate of the thermal system or the set target load rate, determine the target load range that the thermal system needs to enter, and switch to the regulating steam inlet channel 10 corresponding to the target load range. If the load range does not change, maintain the current steam inlet channel operation. If the load range changes, switch from the current regulating steam inlet channel 10 to the regulating steam inlet channel 10 corresponding to the target load range.

[0085] As can be seen, the number of pressure stages 7 required to be put into operation will also change with the change in unit load. By automatically reconfiguring the thermal system state and switching to different regulating steam inlet channels 10, the number of pressure stages 7 after reconfiguration is better matched to the current load rate. To achieve this, there are various combinations of load ranges and regulating steam inlet channels 10. The most basic is one load range corresponding to one regulating steam inlet channel 10, but it is also possible for one load range to correspond to two or more regulating steam inlet channels 10. The reason for switching regulating steam inlet channels 10 can be passive or active. That is, the regulating steam inlet channel 10 can switch when the unit load changes; or a target load rate can be set manually, and the regulating steam inlet channel 10 will actively switch while other devices in the thermal system are adjusting.

[0086] In some embodiments, when the load of the thermal system is increased, the final regulating steam inlet channel to be switched to is determined according to the load increase rate or target load rate requirement. It should be noted that, whether the regulating steam inlet channel 10 is switched actively or passively, as long as the triggering condition for switching the regulating steam inlet channel 10 is met, a parameter of the load increase rate or target load rate requirement will be generated. For example, it is necessary to switch from the third regulating steam inlet channel 103 to the first regulating steam inlet channel 101 or to the second regulating steam inlet channel 102, which will form a final regulating steam inlet channel.

[0087] Once the final regulating steam inlet channel is determined, it can be opened directly. This approach is to improve the load adjustment rate. After opening the final regulating steam inlet channel, other factors are used to stabilize the load. This method is a static adjustment method.

[0088] Alternatively, this approach can be adopted: if there are other intermediate regulating steam inlet channels 10 between the final regulating steam inlet channel and the current regulating steam inlet channel, then the intermediate regulating steam inlet channels 10 are opened sequentially or simultaneously, starting from the current regulating steam inlet channel, until the final regulating steam inlet channel is opened. This means that if it is necessary to switch from the third regulating steam inlet channel 103 to the first regulating steam inlet channel 101, and there is a second regulating steam inlet channel 102 in between, then during the switching process, the second regulating steam inlet channel 102 needs to be opened first as a transition, and finally the first regulating steam inlet channel 101 is opened. It can be seen that this method is a dynamic adjustment method, and the opening status of each regulating steam inlet channel 10 will change during the load increase process.

[0089] During the switching of the regulating steam inlet channel 10, it is determined whether the current load has reached the set value. If it has, and the load is stabilized by regulating boiler 1, the regulating steam inlet channel 10 or the conventional steam inlet channel 42 will not be opened further. The other regulating steam inlet channels 10 except the final regulating steam inlet channel will be closed gradually. That is, the third regulating steam inlet channel 103 will be closed first, and then the second regulating steam inlet channel 102 will be closed. It should be noted that when gradually closing the other regulating steam inlet channels 10 except the final regulating steam inlet channel, they should be closed in order from farthest to near. Of course, they can also be closed at the same time, but they should be closed slowly during the closing process.

[0090] Additionally, if during dynamic adjustment, such as when switching from the third regulating steam inlet channel 103 to the first regulating steam inlet channel 101, the load has already reached the set value when the second regulating steam inlet channel 102 is opened, then the system remains in the second regulating steam inlet channel 102 and the first regulating steam inlet channel 101 is no longer opened. Thus, in some implementations, whether the current load has reached the set value is used as the first priority for determining when to open the regulating steam inlet channel 10.

[0091] Additionally, during the transition phase, i.e. when the second regulating steam inlet channel 102 is opened, a certain proportion of the second regulating steam inlet channel 102 can be opened first, and a certain proportion of the third regulating steam inlet channel 103 can be closed. When the second regulating steam inlet channel 102 is opened to the set proportion or when the third regulating steam inlet channel 103 is closed to a certain proportion, the first regulating steam inlet channel 101 is then opened. The sum of the openings of the three regulating steam inlet channels 10 can be controlled according to a certain functional relationship or a certain value, so that the first regulating steam inlet channel 101 is fully opened and the third regulating steam inlet channel 103 and the second regulating steam inlet channel 102 are closed in sequence.

[0092] In some embodiments, when the thermal system reduces its load, the final regulating steam inlet passage to be switched to is determined according to the load reduction rate requirement. It should be noted that whether the regulating steam inlet passage 10 is switched actively or passively, as long as the triggering condition for switching the regulating steam inlet passage 10 is met, a parameter of the load reduction rate requirement will be generated. For example, whether to switch from the first regulating steam inlet passage 101 to the third regulating steam inlet passage 103 or to the second regulating steam inlet passage 102, that is, a final regulating steam inlet passage will be formed.

[0093] Gradually close the regulating valve 11 corresponding to the current regulating steam inlet passage.

[0094] Judge whether the current load reaches the set value. If it reaches and the load is stabilized by adjusting the boiler 1, then gradually open the regulating valve 11 corresponding to the final regulating steam inlet passage and close the regulating valve 11 corresponding to the current regulating steam inlet passage.

[0095] More specifically, if it is necessary to switch from the first regulating steam inlet passage 101 to the third regulating steam inlet passage 103, first, according to the requirement of the load reduction rate required by the dispatching, gradually close the regulating valve 11 of the first regulating steam inlet passage 101. When the load reaches the set value, while stabilizing the load by adjusting the boiler 1, gradually open the regulating valve 11 of the third regulating steam inlet passage 103 and slowly close the regulating valve 11 of the first regulating steam inlet passage 101.

[0096] In some embodiments, when the load rate of the thermal system is lower than X% of the rated load, open the air regulating valve assembly 18 and input the steam in the corresponding regulating pressure stage group 6 into the adjustable heater 19, where 20% < x% < 60%. Preferably, according to system optimization, for a conventional subcritical unit, x% can be determined to be about 40% through calculation and verification. That is, when the unit load rate is lower than the set value, the steam in the regulating pressure stage group 6 needs to be returned to the adjustable heater 19 and then flow back to the boiler 1.

[0097] In some embodiments, detect the temperature of the boiler 1 flue. If the temperature of the boiler 1 flue is lower than the set temperature value, open the air regulating valve assembly 18 and adjust the return flow of the steam extracted from the regulating pressure stage group 6 by controlling the opening degree of the air regulating valve assembly 18, so as to adjust the temperature of the boiler 1 flue to be higher than the set temperature value.

[0098] In summary, compared with the prior art, the above embodiments provide a steam turbine unit, thermal system and operation method based on series auxiliary regulation. Multiple regulating pressure stage groups 6 are connected in series before the conventional pressure stage group 41. Each regulating pressure stage group 6 has a corresponding regulating steam inlet channel 10 to transport steam. Different regulating pressure stage groups 6 are put into operation according to different load ranges. When the upstream regulating pressure stage group 6 is put into operation, the downstream regulating pressure stage group 6 will also be put into operation due to the series relationship. This realizes the structural adaptability reconstruction of the steam turbine unit, improves the low-load efficiency of the unit, and only requires the axial length space of the unit to realize the construction of different pressure stage 7 structures.

[0099] Since the regulating pressure stage group 6 can fully adopt the full circumferential steam intake method, it can eliminate the problem of uneven circumferential steam intake caused by partial steam intake under low load conditions, which leads to excessive unit vibration.

[0100] The main steam valve 5 and regulating valve 11 installed in the pipeline system are used to control the opening and closing of each regulating steam inlet channel 10. In addition, by setting up a multi-level branch steam pipeline network, a smooth transition can be achieved when switching between different regulating steam inlet channels 10, avoiding sudden changes in steam flow and eliminating potential vibration and safety hazards under low load conditions.

[0101] Under medium and low load conditions, the flue gas temperature of boiler 1 is low, which poses a risk of not meeting the denitrification requirements. By leading an exhaust pipe from the end of the regulating pressure stage group 6 and connecting it to the adjustable heater 19, the water temperature at the inlet of boiler 1 is increased, and the flue gas temperature at the denitrification point is adjusted according to actual needs to meet the denitrification requirements.

[0102] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A steam turbine unit based on series auxiliary regulation, comprising a power cylinder, wherein the power cylinder is any one of a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder, and wherein the power cylinder is provided with a conventional steam inlet passage and a conventional pressure stage group, characterized in that, The working cylinder is also provided with at least one regulating pressure stage group. The regulating pressure stage group is connected in series coaxially before the conventional pressure stage group. Each regulating pressure stage group is provided with at least one pressure stage. The pressure stage is composed of a stationary vane at the front end and a moving vane at the rear end. Each regulating pressure stage group has an independent regulating steam inlet channel. The front end of the regulating steam inlet channel is connected to at least one regulating valve for controlling the on / off of steam flow. The operating load is divided into multiple load ranges, and each load range is associated with a steam inlet channel. The lower the load, the more pressure stages are activated.

2. A steam turbine unit based on series auxiliary regulation according to claim 1, characterized in that, The conventional pressure stage group or at least one of the regulating pressure stage groups adopts a full-circumferential steam inlet method, and no regulating stage is set at its front end.

3. A steam turbine unit based on series auxiliary regulation according to claim 1, characterized in that, The stationary vane in the foremost pressure stage of the regulating pressure stage group, which is furthest from the conventional pressure stage group, is embedded in the inner cylinder of the working cylinder.

4. A steam turbine unit based on series auxiliary regulation according to claim 1, characterized in that, The regulating pressure stage group furthest from the conventional pressure stage group is provided with an regulating stage, and the regulating stage is provided with at least two nozzle groups.

5. A steam turbine unit based on series auxiliary regulation according to any one of claims 1 to 4, characterized in that, Each of the regulating pressure stage groups has a corresponding check valve assembly at its outlet. The check valve assembly is used to open when the corresponding regulating pressure stage group and the regulating pressure stage groups preceding it are in operation, and to close when the corresponding regulating pressure stage group is not in operation and the regulating pressure stage groups or conventional pressure stage groups following it are in operation.

6. A steam turbine unit based on series auxiliary regulation according to claim 5, characterized in that, Each of the pressure regulating stages has an annular channel at its outlet, and the check valve assembly is located at the annular channel.

7. A steam turbine unit based on series auxiliary regulation according to claim 6, characterized in that, The non-return valve assembly includes multiple non-return valve units arranged sequentially along the circumference. Each non-return valve unit includes a rotating shaft and an opening / closing component. The opening / closing component can rotate along the rotating shaft. In the closed state, the axial projection of the opening / closing component is an irregular surface composed of an inner edge line, a first side line, a second side line, and an outer edge line. The irregular surfaces do not overlap. In the closed state, the circle formed by the inner edges of the multiple opening / closing components connected end to end coincides with the inner circle of the annular channel. The outer edges of the multiple opening / closing components connected end to end form a closed shape.

8. A steam turbine unit based on series auxiliary regulation according to claim 7, characterized in that, The outer edge line is a straight line, the closed shape is a polygon, the polygon has ≥3 sides, and the central axis of the rotation axis coincides with the axial projection of the edge line of the polygon.

9. A steam turbine unit based on series auxiliary regulation according to claim 8, characterized in that, The area covered by the inscribed circle of the polygon is greater than or equal to the outer circle of the annular channel.

10. A steam turbine unit based on series auxiliary regulation according to claim 7, characterized in that, The outer edge is an arc, the closed shape is a circle, and the coverage area of ​​the circle is greater than or equal to the outer circle of the annular channel.

11. A steam turbine unit based on series auxiliary regulation according to any one of claims 7 to 10, characterized in that, The opening and closing component flips outward or inward along the rotation axis according to the front and rear pressure difference of the area it is in.

12. A steam turbine unit based on series auxiliary regulation according to claim 11, characterized in that, The rotation angle of the opening and closing component from the closed state to the open state is no greater than 135°.

13. A steam turbine unit based on series auxiliary regulation according to claim 12, characterized in that, The non-return valve unit also includes two positioning components, which are used to fix or buffer the opening and closing components in the closed and open states, respectively.

14. A thermodynamic system based on series auxiliary regulation, characterized in that, The invention includes a boiler and a steam turbine unit based on series auxiliary regulation as described in any one of claims 1 to 13, wherein the working cylinder is a high-pressure cylinder, the boiler is connected to the regulating steam inlet channels one by one through a pipeline system, the pipeline system is provided with a main steam valve for controlling the on / off of the main steam flow of the boiler, and at least one regulating valve is provided between the main steam valve and each regulating steam inlet channel.

15. A thermodynamic system based on series auxiliary regulation according to claim 14, characterized in that, The pipeline system includes a main steam pipeline and at least one branch steam pipeline network. The main steam valve is located on the main steam pipeline, and the branch steam pipeline network consists of several branch steam pipelines, each of which is equipped with a regulating valve.

16. A thermodynamic system based on series auxiliary regulation according to claim 15, characterized in that, It also includes a regenerative system, which includes at least one adjustable heater. At least one steam outlet of the regulating pressure stage group is connected to the adjustable heater via an extraction pipe. The extraction pipe is equipped with an adjusting valve assembly. The adjustable heater is connected to the boiler.

17. An operating method for a thermodynamic system based on series auxiliary regulation as described in claim 16, characterized in that, Includes the following steps: Based on the distance between each regulating pressure level group and the first pressure level of the conventional pressure level group, they are defined sequentially from near to far as the first regulating pressure level group, the second regulating pressure level group, ... the nth regulating pressure level group. The regulating steam inlet channels corresponding to the regulating pressure level groups are defined sequentially as the first regulating steam inlet channel, the second regulating steam inlet channel, ... the nth regulating steam inlet channel. The conventional steam inlet channel is determined as the zeroth steam inlet channel. The operating load of the thermal system is divided into n+1 load intervals, and each load interval is associated with a steam inlet channel. Based on the current operating load rate of the thermal system and the set target load rate, determine the target load range that the thermal system needs to enter, and switch to the regulating steam inlet channel corresponding to the target load range.

18. The operation method of a thermodynamic system based on series auxiliary regulation according to claim 17, characterized in that, When the thermal system is increasing its load, the final regulating steam inlet channel to be switched to is determined according to the load increase demand; Directly open the final regulating steam inlet passage, or; If there are other intermediate regulating steam inlet channels between the final regulating steam inlet channel and the current regulating steam inlet channel, then the intermediate regulating steam inlet channels shall be opened sequentially or simultaneously starting from the current regulating steam inlet channel until the final regulating steam inlet channel is opened. Determine if the current load has reached the set value. If it has, gradually close all regulating steam inlet channels except for the final regulating steam inlet channel.

19. The operation method of a thermodynamic system based on series auxiliary regulation according to claim 17, characterized in that, When the thermal system is reducing its load, the final regulating steam inlet channel to be switched to is determined according to the load reduction requirements; Gradually close the regulating valve corresponding to the current steam inlet channel; Determine whether the current load has reached the set value. If it has, gradually open the regulating valve corresponding to the final regulating steam inlet channel and gradually close the regulating valve corresponding to the current regulating steam inlet channel.

20. A method for operating a thermodynamic system based on series auxiliary regulation according to any one of claims 17 to 19, characterized in that, When the load rate of the thermal system is lower than X% of the rated load, the gas regulating valve assembly is opened to input the steam in the corresponding regulating pressure stage group into the adjustable heater.

21. A method for operating a thermodynamic system based on series auxiliary regulation according to any one of claims 17 to 19, characterized in that, The boiler flue temperature is detected. If the boiler flue temperature is lower than the set temperature value, the gas regulating valve assembly is opened. By controlling the opening degree of the gas regulating valve assembly, the boiler flue temperature is adjusted to be higher than the set temperature value.

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