A guide vane adjustable low-pressure cylinder, steam turbine unit and control method thereof

Abstract

The present application relates to the technical field of steam turbine, and particularly discloses a guide vane adjustable low-pressure cylinder, a steam turbine unit and a control method thereof. The guide vane adjustable low-pressure cylinder comprises a cylinder, an inner ring of a partition plate arranged in the cylinder, and a plurality of guide vanes arranged circumferentially between the cylinder and the inner ring of the partition plate. Each guide vane is rotatably assembled between the cylinder and the inner ring of the partition plate, and a driving end of the guide vane extends out of the cylinder in a sealed structure and is connected with a driving structure outside the cylinder. Under the driving of the driving structure, each guide vane produces a rotating action between the cylinder and the inner ring of the partition plate to adjust the flow area in the cylinder. The present application is aimed at the particularity of the deep peak shaving operation control of the thermal power steam turbine unit with a plurality of low-pressure cylinders, so that the flow area in the low-pressure cylinder is adjustable, the medium-pressure exhaust pressure can be effectively reduced, the working efficiency of the medium-pressure cylinder is improved, and the economy of the unit operation in deep adjustment is ensured.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, specifically to an adjustable guide vane low-pressure cylinder, a steam turbine unit, and its control method. Background Technology

[0002] Most of the thermal power turbine units currently in operation require deep peak-shaving operation control.

[0003] For deep peak-shaving operation of thermal power turbine units with multiple low-pressure cylinders, most of the time it is achieved by cutting off some low-pressure cylinders and allowing all the intermediate-pressure exhaust steam to enter the remaining low-pressure cylinders. The cut-off low-pressure cylinders only retain the necessary cooling steam flow to eliminate factors that affect the safe operation of the unit, such as blade blowout and vibration.

[0004] However, the aforementioned deep peak-shaving operation mode of cutting off part of the low-pressure cylinder will cause the medium-pressure exhaust steam to enter the remaining low-pressure cylinder. Since the flow area in the low-pressure cylinder is difficult to adapt to the work done by all the medium-pressure exhaust steam, the medium-pressure exhaust steam pressure will increase significantly. This will cause the flow of the medium-pressure cylinder to deviate completely from the design conditions, resulting in a significant reduction in the working efficiency of the medium-pressure cylinder and directly affecting the overall operating economy of the unit. Summary of the Invention

[0005] The technical objective of this invention is to address the unique characteristics of deep peak shaving operation control of thermal power turbine units with multiple low-pressure cylinders, as well as the shortcomings of existing technologies, by providing an adjustable guide vane low-pressure cylinder with adjustable flow area that is adapted to deep peak shaving control, and a turbine unit and a control method based on the adjustable guide vane low-pressure cylinder.

[0006] The technical objective of this invention is achieved through the following technical solution: an adjustable low-pressure cylinder with guide vanes, comprising a cylinder, an inner ring of a partition plate arranged in the cylinder, and a plurality of guide vanes arranged circumferentially between the cylinder and the inner ring of the partition plate. Each guide vane is rotatably assembled between the cylinder and the inner ring of the diaphragm, and the drive end of the guide vane extends out of the cylinder in a sealed structure and is connected to the drive structure outside the cylinder. Driven by the drive structure, each guide vane rotates between the cylinder and the inner ring of the diaphragm to adjust the flow area within the cylinder.

[0007] Furthermore, corresponding to the arrangement of the rotatable guide vanes of the same stage, the outer periphery of the cylinder is equipped with a circumferentially displaceable drive ring. The drive ring is connected to the drive end of each guide vane through multiple sets of drive linkages. The drive ring is connected to a power source that drives the circumferential displacement action. Driven by the power source, the drive ring moves in a circumferential direction around the cylinder. The circumferentially displaced drive ring drives the corresponding guide vanes to rotate within the cylinder via each drive link, thereby adjusting the flow area within the cylinder.

[0008] Furthermore, the power source is a hydraulic motor, which is connected to the drive ring via a connecting rod; Under the extension and retraction drive of the hydraulic actuator, the drive ring is driven by the connecting rod to produce a circumferential displacement movement on the outer periphery of the cylinder.

[0009] Furthermore, the tip of the guide vane is rotatably assembled with the inner ring of the diaphragm via a bearing assembly; The root end of the guide vane serves as the driving end and has an outwardly extending driving structure. The root end of the guide vane is sealed and assembled with the cylinder in a rotatable structure through a bearing assembly and a sealing assembly.

[0010] A steam turbine unit includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder arranged in sequence according to the steam power flow path; The low-pressure cylinder is the aforementioned adjustable guide vane low-pressure cylinder structure.

[0011] Furthermore, the turbine unit has a four-exhaust steam turbine structure with two low-pressure cylinders, including low-pressure cylinder A and low-pressure cylinder B; The low-pressure cylinder A is connected to the connecting pipe via a low-pressure steam inlet pipe A, and a low-pressure shut-off valve A is connected to the low-pressure steam inlet pipe A. The low-pressure cylinder B is connected to the connecting pipe via a low-pressure steam inlet pipe B, and a low-pressure shut-off valve B is connected to the low-pressure steam inlet pipe B.

[0012] Furthermore, the low-pressure cylinder A is connected to the connecting pipe bypass via the low-pressure steam inlet bypass A, and the low-pressure steam inlet bypass A is sequentially connected to a bypass flow meter A and a bypass regulating valve A. The low-pressure cylinder B is connected to the connecting pipe bypass via the low-pressure steam inlet bypass B. A bypass flow meter B and a bypass regulating valve B are connected in sequence on the low-pressure steam inlet bypass B.

[0013] A control method for the above-mentioned steam turbine unit, the control method including normal operating conditions and peak-shaving operating conditions; Under normal operating conditions, low-pressure cylinder A and low-pressure cylinder B perform work with the same steam inlet flow rate. When operating under peak-shaving conditions, the following procedure is executed: S1. Fully open the low-pressure shut-off valve A and the bypass regulating valve A respectively, quickly close the low-pressure shut-off valve B, and open the bypass regulating valve B to a certain degree to maintain the necessary cooling steam flow in the low-pressure cylinder B. S2. With the goal of increasing the flow area in low-pressure cylinder A, adjust the rotation angle of the guide vanes in low-pressure cylinder A to control the intermediate-pressure exhaust pressure.

[0014] The beneficial technical effects of this invention are as follows: Addressing the unique characteristics of deep peak-shaving operation control in thermal power turbine units with multiple low-pressure cylinders, the above-mentioned technical measures configure at least one stage guide vane of the low-pressure cylinder as a rotary adjustable structure. This allows for adjustable flow area within the low-pressure cylinder. Thus, during deep peak-shaving operation, when all intermediate-pressure exhaust steam enters the remaining low-pressure cylinders, the flow area within the low-pressure cylinders is adjusted to adapt to the inlet steam pressure, effectively reducing the intermediate-pressure exhaust pressure, improving the working efficiency of the intermediate-pressure cylinders, and ensuring the economic efficiency of the unit during deep peak-shaving. Based on the above-mentioned low-pressure cylinder structure and its peak-shaving control method, the turbine unit can operate economically and safely. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the adjustable low-pressure cylinder with guide vanes of the present invention.

[0016] Figure 2 This is a schematic diagram of the turbine unit of the present invention.

[0017] The markings in the diagram mean: 1-Boiler; 2-High-pressure valve; 3-Medium-pressure valve; 4-High-pressure cylinder; 5-Medium-pressure cylinder; 6-Low-pressure cylinder A; 7-Low-pressure cylinder B; 8-Connecting pipe; 9-Low-pressure steam inlet pipe A; 10-Low-pressure steam inlet pipe B; 11-Connecting pipe bypass; 12-Low-pressure steam inlet pipe bypass A; 13-Low-pressure steam inlet pipe bypass B; 14-Bypass flow meter A; 15-Bypass regulating valve A; 16-Bypass flow meter B; 17-Bypass regulating valve B; 18-Low-pressure shut-off valve A; 19-Low-pressure shut-off valve B; 20-Hydraulic actuator; 21-Transfer connecting rod; 22-Drive ring; 23-Cylinder; 24-Diaphragm inner ring; 25-Guide vane. Detailed Implementation

[0018] This invention relates to the field of steam turbine technology, specifically to an adjustable guide vane low-pressure cylinder, a steam turbine unit based on the low-pressure cylinder structure, and a control method for the steam turbine unit. The technical solution of this invention will be clearly and thoroughly explained below with reference to the accompanying drawings.

[0019] See Figure 2As shown, the steam turbine unit of the present invention includes a boiler 1, a high-pressure cylinder 4, an intermediate-pressure cylinder 5, and two low-pressure cylinders—low-pressure cylinder A6 and low-pressure cylinder B7—forming a four-exhaust structure. The high-pressure cylinder 4, intermediate-pressure cylinder 5, low-pressure cylinder A6, and low-pressure cylinder B7 are arranged in a steam power flow path sequence. Specifically, steam generated by the boiler 1 enters the high-pressure cylinder 4 through a high-pressure steam pipe and a high-pressure valve 2 on the high-pressure steam pipe. Exhaust steam generated by the high-pressure cylinder 4 enters the intermediate-pressure cylinder 5 through a secondary reheat intermediate-pressure steam pipe and a medium-pressure valve 3 on the intermediate-pressure steam pipe. Exhaust steam generated by the intermediate-pressure cylinder 5 enters the low-pressure cylinders A6 and B7 through a connecting pipe 8. Furthermore, to adapt to deep peak-shaving control, exhaust steam generated by the intermediate-pressure cylinder 5 enters the low-pressure cylinders A6 and B7 through a bypass 11 in the connecting pipe.

[0020] More specifically, low-pressure cylinder A6 is connected to connecting pipe 8 via low-pressure steam inlet pipe A9. A low-pressure shut-off valve A18 is connected to low-pressure steam inlet pipe A9 to control the entry of steam into low-pressure cylinder A6. Low-pressure cylinder B7 is connected to connecting pipe 8 via low-pressure steam inlet pipe B10. A low-pressure shut-off valve B19 is connected to low-pressure steam inlet pipe B10 to control the entry of steam into low-pressure cylinder B7. In other words, connecting pipe 8 corresponds to two low-pressure cylinders—low-pressure cylinder A6 and low-pressure cylinder B7—and leads out two low-pressure steam inlet pipes—namely, low-pressure steam inlet pipe A9 and low-pressure steam inlet pipe B10.

[0021] Low-pressure cylinder A6 is connected to connecting pipe bypass 11 via low-pressure steam inlet bypass A12. A bypass flow meter A14 and a bypass regulating valve A15 are sequentially connected to low-pressure steam inlet bypass A12 according to the steam flow path to control the steam flow rate entering low-pressure cylinder A6. Low-pressure cylinder B7 is connected to connecting pipe bypass 11 via low-pressure steam inlet bypass B13. A bypass flow meter B16 and a bypass regulating valve B17 are sequentially connected to low-pressure steam inlet bypass B13 according to the steam flow path to control the steam flow rate entering low-pressure cylinder B7. In other words, connecting pipe bypass 11 corresponds to two low-pressure cylinders—low-pressure cylinder A6 and low-pressure cylinder B7—and leads out two low-pressure steam inlet bypasses—namely, low-pressure steam inlet bypass A12 and low-pressure steam inlet bypass B13.

[0022] The turbine units with the above-mentioned structure operate under two environments: normal operating conditions and deep peak-shaving operating conditions. Specifically: Under normal operating conditions, the exhaust steam generated by the intermediate pressure cylinder 5 enters the low pressure cylinder A and the low pressure cylinder B through the connecting pipe 8 and the corresponding low pressure steam inlet pipe, as well as through the connecting pipe bypass 11 and the corresponding low pressure steam inlet pipe bypass. The low pressure cylinder A and the low pressure cylinder B perform work with basically the same steam inlet flow rate. Under deep peak shaving operation conditions, assuming low-pressure cylinder A is retained and low-pressure cylinder B is disconnected, the following control process is executed: Fully open the low-pressure shut-off valve A on the low-pressure steam inlet pipe A and the bypass regulating valve A on the low-pressure steam inlet pipe bypass A respectively; Quickly close the low-pressure shut-off valve B on the low-pressure steam inlet pipe B; Open the bypass regulating valve B on the low-pressure steam inlet pipe bypass B to a certain degree to maintain the necessary cooling steam flow in the low-pressure cylinder B, so as to eliminate factors that affect the safe operation of the unit, such as blade blowing and vibration. In this way, the exhaust steam generated by the intermediate pressure cylinder 5, except for the necessary flow into the low pressure cylinder B, all enters the low pressure cylinder A to do work.

[0023] However, since all the intermediate-pressure exhaust steam enters the low-pressure cylinder A, if the flow area in the low-pressure cylinder A is constant, it is difficult to adapt to the work done by all the intermediate-pressure exhaust steam entering. This will cause the intermediate-pressure exhaust steam pressure to rise significantly, which will cause the flow of the intermediate-pressure cylinder 5 to deviate completely from the design conditions, resulting in a significant reduction in the work efficiency of the intermediate-pressure cylinder 5, which will directly affect the overall operating economy of the unit.

[0024] Therefore, the low-pressure cylinder A and low-pressure cylinder B of the aforementioned steam turbine unit respectively adopt the following... Figure 2 The structure shown is an adjustable flow area in the low-pressure cylinder, meaning that the low-pressure cylinders A and B of the above-mentioned turbine unit adopt adjustable guide vane low-pressure cylinder structures.

[0025] See Figure 2 As shown, the aforementioned low-pressure cylinder with adjustable guide vanes includes a cylinder 23, a partition inner ring 24 arranged within the cylinder 23, and multiple guide vanes 25 arranged circumferentially between the cylinder 23 and the partition inner ring 24.

[0026] Specifically, the crown end of the guide vane 25 is rotatably assembled with the inner ring 24 of the diaphragm via a bearing assembly, i.e., the bearing assembly is fixed on the inner ring 24 of the diaphragm, and the crown end of the guide vane 25 is mounted with the corresponding bearing assembly on the inner ring 24 of the diaphragm as a support carrier. The root end of the guide vane 25 serves as the driving end, having an outwardly axially extending driving structure—i.e., the driving end. The root end of the guide vane 25 is rotatably sealed and assembled with the cylinder 23 via a bearing assembly and a sealing assembly; that is, the cylinder 23 has a mounting hole corresponding to the current installation position of the guide vane 25, and a bearing assembly is assembled in the mounting hole. The mounting hole at the inner end and / or outer end of the bearing assembly is sealed by a dynamic sealing structure—such as a packing assembly. The driving end of the root end of the guide vane 25 extends to the outside of the cylinder 23 through the bearing assembly on the cylinder 23. Thus, each guide vane 25 of the same stage is rotatably assembled between the cylinder 23 and the inner ring 24 of the partition plate, and the drive end of the guide vane 25 extends out of the cylinder 23 in a sealed structure and is connected to the drive structure outside the cylinder 23.

[0027] Since the drive ends of the guide vanes 25 of the same stage are arranged at regular circumferential intervals on the outer periphery of the cylinder 23, a circumferentially displaceable drive ring 22 is mounted on the outer periphery of the cylinder 23 corresponding to the arrangement of the rotatable guide vanes 25 of the same stage. This drive ring 22 can be a flexible chain structure or a rigid ring structure. The drive ring 22 is connected to the drive end of each guide vane 25 through multiple sets of corresponding drive linkages and locked with nuts. Of course, to ensure the smooth circumferential displacement of the drive ring 22 on the outer periphery of the cylinder 23, a slide rail can be configured on the outer periphery of the cylinder 23 to allow the drive ring 22 to move along a set circumferential trajectory. The drive ring 22 is connected to a power source that can drive it to produce circumferential displacement.

[0028] The aforementioned power source is a hydraulic actuator 20, which is fixedly connected to the drive ring 22 via a connecting rod 21. The hydraulic actuator 25 performs axial extension and retraction on a bracket outside the cylinder 23. Driven by the extension and retraction of the hydraulic actuator 25, the drive ring 22 is driven to perform circumferential displacement around the cylinder 23 via the connecting rod 21. Thus, the circumferentially displaced drive ring 22 drives the corresponding guide vanes 25 to rotate within the cylinder 23 via each drive connecting rod. Each rotating guide vane 25 adjusts the flow area of ​​the current stage, thereby achieving flow area adjustment within the cylinder 23.

[0029] Thus, in the deep peak-shaving operation control of the above-mentioned steam turbine unit, since all the intermediate-pressure exhaust steam enters the low-pressure cylinder A, in order to make the flow area in the low-pressure cylinder A adapt to the work done by all the intermediate-pressure exhaust steam entering, the rotation angle of the guide vanes in the low-pressure cylinder A is adjusted with the goal of increasing the flow area in the low-pressure cylinder A, thereby controlling the intermediate-pressure exhaust steam pressure.

[0030] The above specific technical solutions are only used to illustrate the present invention, and are not intended to limit it.

[0031] Although the present invention has been described in detail with reference to the specific technical solutions described above, those skilled in the art should understand that modifications can still be made to the specific technical solutions described above, or equivalent substitutions can be made to some of the technical features, such as using a condenser cooled by circulating water in an indirect air-cooled unit; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the present invention.

Claims

1. A guide vane adjustable low-pressure cylinder, comprising a cylinder (23), a partition inner ring (24) arranged in the cylinder (23), and a plurality of guide vanes (25) arranged circumferentially between the cylinder (23) and the partition inner ring (24). Its features are: Each guide vane (25) is rotatably assembled between the cylinder (23) and the inner ring (24) of the partition plate, and the drive end of the guide vane (25) extends out of the cylinder (23) in a sealed structure and is connected to the drive structure outside the cylinder (23). Driven by the drive structure, each guide vane (25) rotates between the cylinder (23) and the inner ring (24) of the partition plate to adjust the flow area inside the cylinder (25).

2. The adjustable low-pressure cylinder with guide vanes according to claim 1, characterized in that: Corresponding to the arrangement of the same level of rotatable guide vanes (25), the outer periphery of the cylinder (23) is equipped with a circumferentially displaceable drive ring (22). The drive ring (22) is connected to the drive end of each guide vane (25) through multiple sets of drive linkages. The drive ring (22) is connected to a power source that drives the circumferential displacement action. Driven by the power source, the drive ring (22) generates a circumferential displacement on the outer periphery of the cylinder (23). The circumferentially displaced drive ring (22) drives the corresponding guide vane (25) to rotate in the cylinder (23) through each drive link, so as to adjust the flow area in the cylinder (23).

3. The adjustable low-pressure cylinder with guide vanes according to claim 2, characterized in that: The power source is a hydraulic motor (20), which is connected to the drive ring (22) via a connecting rod (21); Under the extension and retraction drive of the hydraulic actuator (25), the drive ring (22) is driven by the adapter link (21) to generate circumferential displacement on the outer periphery of the cylinder (23).

4. The adjustable low-pressure cylinder with guide vanes according to claim 1, characterized in that: The tip of the guide vane (25) is rotatably assembled with the inner ring (24) of the partition plate via a bearing assembly; The root end of the guide vane (25) serves as the driving end and has an outwardly extending driving structure. The root end of the guide vane (25) is sealed and assembled with the cylinder (23) in a rotatable structure through a bearing assembly and a sealing assembly.

5. A steam turbine unit, comprising a high-pressure cylinder (4), an intermediate-pressure cylinder (5), and a low-pressure cylinder arranged in sequence in the steam power flow path; Its features are: The low-pressure cylinder is the guide vane adjustable low-pressure cylinder structure as described in any one of claims 1 to 4.

6. The steam turbine unit according to claim 5, characterized in that: The turbine unit is a four-exhaust steam turbine with two low-pressure cylinders, including low-pressure cylinder A (6) and low-pressure cylinder B (7). The low-pressure cylinder A (6) is connected to the connecting pipe (8) through the low-pressure steam inlet pipe A (9), and a low-pressure shut-off valve A (18) is connected to the low-pressure steam inlet pipe A (9). The low-pressure cylinder B (7) is connected to the connecting pipe (8) through the low-pressure steam inlet pipe B (10), and a low-pressure shut-off valve B (19) is connected to the low-pressure steam inlet pipe B (10).

7. The steam turbine unit according to claim 6, characterized in that: The low-pressure cylinder A (6) is connected to the connecting pipe bypass (11) through the low-pressure steam inlet bypass A (12). The low-pressure steam inlet bypass A (12) is connected in sequence to the bypass flow meter A (14) and the bypass regulating valve A (15). The low-pressure cylinder B (7) is connected to the connecting pipe bypass (11) through the low-pressure steam inlet bypass B (13). The low-pressure steam inlet bypass B (13) is connected in sequence to the bypass flow meter B (16) and the bypass regulating valve B (17).

8. A control method for a steam turbine unit according to claim 7, the control method comprising a normal operating condition environment and a peak-shaving operating condition environment; Its features are: Under normal operating conditions, low-pressure cylinder A and low-pressure cylinder B perform work with the same steam inlet flow rate. When operating under peak-shaving conditions, the following procedure is executed: S1. Fully open the low-pressure shut-off valve A and the bypass regulating valve A respectively, quickly close the low-pressure shut-off valve B, and open the bypass regulating valve B to a certain degree to maintain the necessary cooling steam flow in the low-pressure cylinder B. S2. With the goal of increasing the flow area in low-pressure cylinder A, adjust the rotation angle of the guide vanes in low-pressure cylinder A to control the intermediate-pressure exhaust pressure.

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