Turbine and its overspeed and emergency shutdown protection device

Abstract

The application provides a steam turbine and a protection device for overspeed and emergency shutdown of the steam turbine. The protection device comprises a critical breaker system, a safety oil path connected to an oil inlet side of the critical breaker system, and used for inputting safety oil into the critical breaker system; a tripping oil path connected to the oil inlet side of the critical breaker system, and used for inputting tripping oil into the critical breaker system; and a discharge oil pipe connected to an oil outlet side of the critical breaker system and a main steam valve, wherein a main steam valve closing electromagnetic valve unit is connected to the discharge oil pipe, and used for controlling opening and closing of the discharge oil pipe. The protection device can realize the same effect of AST electromagnetic valve protection by installing the main steam valve closing electromagnetic valve unit, and can prevent the occurrence of flywheel accidents caused by the failure of the critical breaker slide valve to move due to jamming, the failure of the steam turbine to safely shut down, and the failure of the steam turbine overspeed protection to move, and greatly improves the safety of the steam turbine operation.

Description

Technical Field

[0001] This application relates to the technical field of steam turbines, specifically to a steam turbine and its overspeed and emergency shutdown protection device. Background Technology

[0002] Conventional technical solutions typically include only one on-site emergency stop button for steam turbines, with only one side protection. This cannot guarantee redundant control for emergency stops, overspeeding, and other situations, posing a safety hazard. Utility Model Content

[0003] The first aspect of this application provides a protection device for turbine overspeed and emergency shutdown. The protection device includes an emergency trip system. A safety oil circuit is connected to the oil inlet side of the emergency trip system, which is used to input safety oil into the emergency trip system. A brake-operated oil circuit is also connected to the oil inlet side of the emergency trip system, which is used to input brake-operated oil into the emergency trip system. The oil outlet side of the emergency trip system is connected to the main steam valve via an oil discharge pipe. A main steam valve closing solenoid valve unit is also connected to the oil discharge pipe, which is used to control the opening and closing of the oil discharge pipe.

[0004] In some alternative embodiments, the main steam valve closing solenoid valve unit includes a solenoid valve and a manual valve connected in series.

[0005] In some alternative embodiments, the solenoid valve is connected to the EST system.

[0006] In some optional embodiments, the protective device further includes a field emergency stop button connected to the EST system.

[0007] In some alternative embodiments, the main steam valve closing solenoid valve unit further includes a front bearing housing, and the solenoid valve is connected to the front bearing housing.

[0008] In some alternative embodiments, the main steam valve includes a left main steam valve and a right main steam valve connected in parallel.

[0009] In some optional embodiments, the emergency shutdown system is further connected to an additional safety oil circuit on the oil inlet side, the additional safety oil circuit being used to input additional safety oil into the emergency shutdown system.

[0010] In some optional embodiments, the additional safety oil line is connected to a local emergency stop button and an AST solenoid valve assembly, which is connected to the EST system.

[0011] In some optional embodiments, the EST system is also connected to the DCS console emergency stop button, the DEH system, and the TSI system.

[0012] Secondly, embodiments of this application provide a steam turbine, which includes the protective device described in the above embodiments.

[0013] The turbine overspeed and emergency shutdown protection device provided in this application embodiment can achieve the same effect as the AST solenoid valve protection by installing the main steam valve closing solenoid valve unit. This is equivalent to adding an extra safety protection barrier for the turbine, which can prevent runaway accidents caused by the emergency trip valve jamming and failure to operate, and the turbine overspeed protection failing to operate, thus greatly improving the safety of turbine operation. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of a protection device for steam turbine overspeed and emergency shutdown.

[0016] Figure 2 yes Figure 1 The EST protection logic diagram of the turbine overspeed and emergency shutdown protection device in the embodiment;

[0017] Figure 3 This is a schematic flowchart of another embodiment of the protection device for turbine overspeed and emergency shutdown;

[0018] Figure 4 yes Figure 3 The embodiment shows the EST protection logic diagram of the turbine overspeed and emergency shutdown protection device. Detailed Implementation

[0019] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the application. Similarly, the following embodiments are only some, not all, embodiments of the present application, and all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present application.

[0020] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationships and movement of components in a specific posture (as shown in the figures). If the specific posture changes, the directional indication will also change accordingly. The terms "comprising" and "having," and any variations thereof, in the embodiments of this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or components inherent to these processes, methods, products, or devices.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] Please see Figure 1 , Figure 1 This is a schematic diagram of a protection device for overspeed and emergency shutdown of a steam turbine. The emergency shutdown and overspeed protection process of a 150MW steam turbine is used as an example for explanation.

[0023] (1) The turbine emergency stop is equipped with an emergency stop button on the on-site turbine head safety control box and an emergency stop button 101 on the DCS (Distributed Control System) control panel.

[0024] When the emergency stop button on the on-site turbine safety control box is pressed, the additional safety oil pressure is released, the emergency trip valve falls (trips), thereby releasing the main steam valve control oil, the main steam valve spring force closes, and the turbine trips.

[0025] When the emergency stop button 101 on the DCS control panel is pressed, the turbine protection is activated, opening the AST (Auto Stop Trip) solenoid valve 102, releasing the additional safety oil pressure, causing the emergency trip valve to fall (trip), thereby releasing the main steam valve control oil, closing the main steam valve with spring force, and tripping the turbine.

[0026] (2) The turbine overspeed protection system incorporates three measures to prevent turbine overspeed: 103% OPC overspeed protection (OPC: Overspeed Protection Control), 110% electrical overspeed trip (AST), and mechanical overspeed trip. OPC overspeed protection activates when the turbine load shedding oil switch trips or the generator speed exceeds 3090 RPM before grid connection. This causes all regulating valves to immediately close and remain closed for 3 seconds, or until the speed drops to 3060 RPM before reopening. When 103% overspeed protection activates, only the speed regulating valve closes; the main steam valve remains open, preventing turbine tripping. After 103% overspeed protection, the turbine maintains a speed of 3000 RPM. AST overspeed trip refers to the overspeed trip command issued by DEH (Digital Electric Hydraulic Control System) system 103 and TSI (Turbine Supervisory Instrumentation) system 104 to ETS (Emergency Trip System) system 105 when the speed exceeds 3300 RPM. This command opens AST solenoid valve 102 (including the first AST solenoid valve 1021 (also known as AST solenoid valve 1) and the first AST solenoid valve 1022 (also known as AST solenoid valve 2) connected in parallel), releasing the additional safety oil pressure. The emergency trip valve slide valve falls (trips), thereby releasing the control oil of the main steam valve (including the left main steam valve 106 and the right main steam valve 107). The main steam valve closes due to spring force, and the turbine trips.

[0027] Mechanical overspeed tripping refers to the situation where the speed exceeds the operating speed of the mechanical impactor, causing the impactor to fly out under the action of centrifugal force, which triggers the safety system (crisis circuit breaker slide valve to fall), thereby releasing the main steam valve control oil, closing the main steam valve spring force, and tripping the turbine.

[0028] The diagram shows the emergency shut-off system marked 108, with the oil inlet side on the left and the oil outlet side on the right; and the on-site emergency stop button marked 109.

[0029] Please see Figure 2 , Figure 2 yes Figure 1 The embodiment shows the EST protection logic diagram of the turbine overspeed and emergency shutdown protection device.

[0030] The turbine overspeed and emergency shutdown protection devices in the above embodiments still have room for improvement:

[0031] ① The turbine's regulating and safety system and lubrication system use 32L-TSA turbine oil. The oil is easily affected by temperature, moisture and impurities, which can cause scaling and oxidation. The emergency shut-off valve in the regulating and safety system is prone to jamming.

[0032] ②The turbine has a minor overhaul cycle of about once a year. The emergency shut-off system is only tested once a year during startup. During normal operation, it is always in the activated state, meaning the emergency shut-off valve is always in the same position. If the valve does not move for a long time, it is prone to jamming.

[0033] ③ The emergency stop mechanisms at the turbine head safety control box, DCS control panel, and AST overspeed trip protection are activated by pressing the emergency stop button at the site or opening the AST solenoid valve. This releases the additional safety oil pressure in the emergency trip system, causing the emergency trip valve to drop (trip). The main steam valve control safety oil is then depressurized through the emergency trip system, closing the main steam valve and tripping the turbine. If an emergency shutdown is required during turbine operation, jamming of the emergency trip valve will prevent emergency shutdown from being achieved either at the site or through the DCS, posing a serious threat to the safe operation of the turbine.

[0034] ④ Mechanical overspeed trip occurs when the turbine speed reaches 3300 RPM. The emergency trip system striker is ejected under centrifugal force, causing the emergency trip lever to drop (trip the circuit breaker). The main steam valve control safety oil is then depressurized through the emergency trip system, closing the main steam valve and tripping the turbine. However, if the emergency trip valve is jammed, the turbine's mechanical overspeed protection will also fail, potentially leading to a runaway accident.

[0035] ⑤ In summary, both emergency shutdown and overspeed protection of the steam turbine rely on the emergency trip system to close and trip the main steam valve. The proper functioning of the emergency trip valve is crucial for the safe operation of the steam turbine. Furthermore, during operation, there have been instances where the emergency trip valve has become stuck, preventing emergency shutdown and resulting in unsafe turbine shutdown and significant safety risks such as overspeed.

[0036] In view of this, the embodiments of this application further improve the protection devices for turbine overspeed and emergency shutdown. Please refer to [link to relevant documentation]. Figure 3 , Figure 3This is a schematic diagram of another embodiment of the protection device for turbine overspeed and emergency shutdown. The protection device includes an emergency trip system 108. The oil inlet side (left side in the figure) of the emergency trip system 108 is connected to a safety oil circuit 110, which supplies safety oil to the emergency trip system 108. The oil inlet side of the emergency trip system 108 is also connected to a brake-operated oil circuit 111, which supplies brake-operated oil to the emergency trip system 108. The oil outlet side (right side in the figure) of the emergency trip system 108 is connected to the main steam valves (including a left main steam valve 106 and a right main steam valve 107 connected in parallel) via an oil discharge pipe 112. The oil discharge pipe 112 is also connected to a main steam valve closing solenoid valve unit 113, which controls the opening and closing of the oil discharge pipe 112.

[0037] Optionally, the main steam valve closing solenoid valve unit 113 in this embodiment includes a solenoid valve 1131 and a manual valve 1132 connected in series. The solenoid valve 1131 is connected to the EST system 105. The main steam valve closing solenoid valve unit 113 also includes a front bearing housing 1133, and the solenoid valve 1131 is connected to the front bearing housing 1133. In addition, the protective device also includes a local emergency stop electrical button 114, which is connected to the EST system 105. The local emergency stop electrical button 114 consists of a set of two buttons connected to normally open contacts. When both buttons are pressed simultaneously, the turbine emergency shutdown protection activates to prevent accidental activation by on-site personnel.

[0038] Optionally, in this embodiment, the emergency shut-off system 108 is further connected to an additional safety oil circuit 115 on its oil inlet side. The additional safety oil circuit 115 is used to input additional safety oil into the emergency shut-off system 108. The diameter of the unloading oil pipe 112 is the same as that of the safety oil pipe 110, which is DN40. A DN40, AC220V solenoid valve 1131 is used, and it is of the type that opens when energized and closes when de-energized. The installed manual valve 1132 is mainly used for media isolation during maintenance of the solenoid valve 1131 in case of failure, and it is a DN40, PN25 stainless steel gate valve.

[0039] The additional safety oil circuit 115 is connected to an emergency stop button 109 and an AST solenoid valve assembly 102 (including a first AST solenoid valve 1021 (also known as AST solenoid valve 1) and a first AST solenoid valve 1022 (also known as AST solenoid valve 2) connected in parallel). The AST solenoid valve assembly 102 is connected to the EST system 105. Optionally, the EST system 105 is also connected to a DCS console emergency stop button 101, a DEH system 103, and a TSI system 104.

[0040] The turbine overspeed and emergency shutdown protection device in this application embodiment further solves the following technical problems:

[0041] 1. Installing the main steam valve closing solenoid valve unit 113 can achieve the same effect as the AST solenoid valve protection, which is equivalent to adding an extra safety protection barrier for the turbine. It can prevent runaway accidents caused by the emergency trip valve jamming and failure to operate, or by the turbine overspeed protection failing to activate.

[0042] 2. An additional on-site emergency stop electrical button 114 is added to prevent damage to the turbine or major safety accidents caused by the original on-site emergency stop button becoming ineffective due to jamming of the emergency shut-off valve.

[0043] 3. The protection logic of the steam turbine ETS has been optimized and improved, which is more conducive to the safe operation of the steam turbine. Please refer to [link / reference needed]. Figure 4 , Figure 4 yes Figure 3 The embodiment shows the EST protection logic diagram of the turbine overspeed and emergency shutdown protection device. The field emergency stop electrical button control signal is added to the ETS protection logic condition. After the ETS protection is activated, there is a 1-second delay before opening the main steam valve and closing the solenoid valve.

[0044] Through improved turbine emergency shutdown and overspeed protection procedures and Figure 1 Compared to the process described in the embodiment, this method significantly improves the safety of turbine operation and has the following advantages:

[0045] 1. In addition to the three measures to prevent turbine overspeed, namely 103% OPC overspeed protection, 110% electrical overspeed trip (AST), and mechanical overspeed trip, a fourth measure to prevent overspeed is added: rapid closing of the main steam valve. This greatly improves the safety of turbine operation and prevents overspeed runaway accidents.

[0046] 2. Whether it's an emergency shutdown of the steam turbine or overspeed protection, the only critical device for the original process protection action is the emergency trip system. In the event of failure of the steam turbine emergency trip system, the steam turbine can be tripped by opening the main steam valve and closing the solenoid valve, achieving the same effect as the emergency trip system and increasing the redundancy of the steam turbine safety protection.

[0047] 3. When an emergency occurs during the operation of the steam turbine and an emergency stop is required, if both the on-site emergency stop button and the emergency stop button on the DCS control panel fail, the on-site emergency stop electrical button can be used to trip the turbine and prevent damage to the steam turbine or the escalation of the accident.

[0048] 4. The main steam valve control oil is released by opening the main steam valve and closing the solenoid valve. There are no other devices in the oil circuit, and the main steam valve closes quickly, which can avoid safety accidents.

[0049] In addition, this application also provides a steam turbine that includes the protective device described in the foregoing embodiments. Other structures of the steam turbine are within the understanding of those skilled in the art and will not be described in detail here.

[0050] The steam turbine provided in this application embodiment has an overspeed and emergency shutdown protection device that achieves the same effect as the AST solenoid valve protection by installing a main steam valve closing solenoid valve unit. This is equivalent to adding an extra safety protection barrier for the steam turbine, which can prevent runaway accidents caused by the emergency trip valve jamming and failure to operate, and the steam turbine overspeed protection failing to operate, thus greatly improving the safety of steam turbine operation.

[0051] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. Any equivalent device or equivalent process transformation made based on the content of this application specification and drawings, or direct or indirect application in other related technical fields, are similarly included in the patent protection scope of this application.

Claims

1. A safeguard for the overspeed and emergency shutdown of a steam turbine, characterized in that, The protection device comprises an emergency trip system, an oil safety path connected to an oil inlet side of the emergency trip system, the oil safety path being used for inputting safety oil to the emergency trip system, a trip oil path connected to the oil inlet side of the emergency trip system, the trip oil path being used for inputting trip oil to the emergency trip system, and a main steam gate connected to an oil outlet side of the emergency trip system through a discharge oil pipe, the discharge oil pipe being further connected with a main steam gate closing electromagnetic valve unit, the main steam gate closing electromagnetic valve unit being used for controlling opening and closing of the discharge oil pipe.

2. The guard of claim 1, wherein The main steam gate closing electromagnetic valve unit comprises an electromagnetic valve and a manual valve connected in series.

3. The guard of claim 2, wherein, The electromagnetic valve is connected with an EST system.

4. The guard of claim 3, wherein, The protection device further comprises an on-site emergency stop electric button connected with the EST system.

5. The guard of claim 3, wherein, The main steam gate closing electromagnetic valve unit further comprises a front bearing box, and the electromagnetic valve is connected with the front bearing box.

6. The guard of claim 1, wherein The main steam gate comprises a left main steam gate and a right main steam gate connected in parallel.

7. The guard of claim 1, wherein The oil inlet side of the emergency trip system is further connected with an additional safety oil path, the additional safety oil path being used for inputting additional safety oil to the emergency trip system.

8. The guard of claim 7, wherein, The additional safety oil path is connected with an on-site emergency stop button and an AST electromagnetic valve group, the AST electromagnetic valve group being connected with an EST system.

9. The guard of claim 8, wherein, The EST system is further connected with a DCS operation platform emergency stop button, a DEH system and a TSI system.

10. A steam turbine, characterized by The steam turbine comprises the protection device according to any one of claims 1-9.

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