Processing method for jamming fault of medium-pressure steam valve of steam turbine

Abstract

The invention discloses a steam turbine medium-pressure steam valve jamming fault processing method, which comprises the following steps of: turning and milling the end surface of a valve shaft of a mechanical execution end of a steam turbine medium-pressure main steam valve, arranging an inner hexagonal device, processing a lifting ring hole in the end surface of the valve shaft, and detecting the deviation between two symmetrical points in the circular axis direction of the valve shaft by adopting a professional measuring tool. The requirement deviation value is not larger than 0.04 mm, it is guaranteed that the basic state of the valve shaft meets the follow-up machining and using requirements, a special-shaped opening tool matched with a valve shaft inner hexagonal device is manufactured, the tool is made of 40Cr and needs to be subjected to thermal refining, the strength and durability of the tool are guaranteed, and the stress requirement in the valve opening and closing process is met. The invention relates to the technical field of steam turbine equipment improvement and maintenance, and the method realizes flexible opening and closing of a jammed valve, avoids major accidents and ensures safe, stable and economical operation of a unit by modifying a valve shaft structure, designing a special tool and matching with external force driving.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of improving and maintaining steam turbine equipment, in particular to a method for processing sticking fault of medium-pressure steam valve in steam turbine. BACKGROUND

[0002] In the operation system of power plant steam turbine, the medium-pressure main steam valve is a key component for controlling the steam into the medium-pressure cylinder, which is driven by an oil motor to realize rapid opening and closing, and directly affects the start-stop process and normal load regulation of the steam turbine. However, the existing medium-pressure main steam valve of the steam turbine is prone to sticking fault due to multiple factors during long-term operation and start-stop process, and the specific problems are as follows:

[0003] Insufficient hot-state expansion gap: the expansion gap reserved between the valve shaft and the valve body and the end cover of the medium-pressure main steam valve of the steam turbine is not suitable for high-temperature working conditions, and when in hot-state operation, the deformation of each component is squeezed by each other, resulting in valve sticking and unable to normally open and close.

[0004] Oxidation corrosion effect: the shaft and the bushing are in a high-temperature operating environment for a long time, and are prone to oxidation corrosion and produce oxide skin, which increases the friction resistance between components and causes sticking.

[0005] Insufficient material performance: the shaft and the sleeve are subjected to high-temperature load for a long time, and if the material cannot meet the requirements of high-temperature working conditions, bending deformation is prone to occur, further causing valve sticking.

[0006] The sticking of the medium-pressure main steam valve can cause serious safety and economic problems: when the valve cannot be closed, the load of the unit changes suddenly after load rejection, the steam flow and state through the flow passage of the steam turbine change, the axial thrust of the rotor is abnormal, the axial displacement indication value changes suddenly, the thrust bearing and the coupling bolt are subjected to a large mechanical impact, which can easily cause the unit to overspeed, and even cause the steam turbine generator unit to fly and be damaged; when the valve cannot be opened, the rotor is subjected to unbalanced steam flow impact during the start-up process of the steam turbine, which induces vibration mutation, triggers vibration protection action and causes shutdown; if the stuck valve is intervened by external force during the start-stop process, the mechanical actuator will be deformed, the shaft end seal will be ineffective, and serious gas leakage will be caused, which not only destroys the stability of the unit operation, but also reduces the operation economy. At present, there is no specific safety treatment method to solve the above problems. SUMMARY

[0007] In view of the above situation, in order to make up for the above-mentioned defects, the present application provides a method for processing sticking fault of medium-pressure steam valve in steam turbine, which realizes flexible opening and closing of the stuck valve by modifying the valve shaft structure, designing special tools and cooperating with external force driving, avoids major accidents, and ensures safe, stable and economic operation of the unit.

[0008] The present application provides the following technical solutions: the present application provides a method for processing sticking fault of medium-pressure steam valve in steam turbine, which comprises:

[0009] I. Device design and processing:

[0010] 1. The valve shaft end face of the mechanical execution end of the intermediate pressure main steam valve in the steam turbine is turned and milled to open an inner hexagonal device. At the same time, a lifting eye hole is machined on the valve shaft end face. The deviation of two points symmetrically located on the circular shaft of the valve shaft is detected using professional measuring tools. The deviation value is required to be not more than 0.04 mm to ensure that the basic state of the valve shaft meets the requirements of subsequent processing and use.

[0011] 2. A special-shaped opening tool is made to match the inner hexagonal device of the valve shaft. The tool is made of 40Cr and needs to be quenched and tempered to ensure the strength and durability of the tool and meet the force requirement during valve opening and closing.

[0012] 3. A connecting device for connecting the valve shaft and the special-shaped opening tool is prepared to ensure the stability of the connecting structure and effectively transfer external force. A chain hoist is also prepared, which will cooperate with the external lifting point to drive the valve opening and closing.

[0013] II. Assembly and connection:

[0014] 1. The machined valve shaft and the completed special-shaped opening tool are combined and installed through the connecting device to ensure precise cooperation between the inner hexagonal device and the special-shaped opening tool without looseness or deviation. After installation, the chain hoist is connected with the lifting eye hole on the valve shaft end face, and the bridge crane in the steam turbine workshop is determined as the external driving lifting point. The chain hoist is suspended below the lifting point of the bridge crane to form a complete external driving system.

[0015] III. Fault handling operation:

[0016] 1. When the intermediate pressure main steam valve of the steam turbine has a jamming fault, the above-mentioned assembled processing system is started: by adjusting the lifting point position of the bridge crane and cooperating with the stretching and contracting action of the chain hoist, stable external force is applied to drive the valve shaft movement, realizing flexible opening and closing of the intermediate pressure main steam valve, solving the jamming problem. The entire operation process can avoid the problems of mechanical execution mechanism deformation and shaft end seal failure caused by traditional external intervention, ensuring the safety and controllability of valve opening and closing action.

[0017] IV. Maintenance tips:

[0018] 1. Pay special attention to the fault points prone to jamming of the valve, such as the gap between the door shaft and the door body, the contact surface between the door shaft and the bushing, and the material state of the door shaft and the sleeve, and make good daily inspection records.

[0019] 2. Regularly carry out valve activity test to timely find potential jamming hidden dangers.

[0020] 3, Once the valve is found to be stuck or other abnormal conditions, the relevant operation should be stopped immediately, find out the cause of the failure and use the method of the application or other effective way to eliminate the fault, avoid the expansion of the fault and cause major accidents.

[0021] The processing method for the intermediate-pressure steam valve sticking fault of a steam turbine has the advantages that:

[0022] 1. By using the special internal hexagonal device, the special-shaped opening tool and the standardized connection and driving structure, the problems of mechanical actuator deformation and shaft end air leakage caused by traditional external intervention are avoided, and the equipment damage and safety accident risk are reduced.

[0023] 2. The method can realize the rapid opening and closing of the intermediate-pressure main steam valve during the start and stop of the steam turbine, solve the sticking fault, effectively avoid the steam turbine overspeed caused by the valve being unable to close, and avoid the major accidents such as steam turbine single-side steam admission vibration trip caused by the valve being unable to open.

[0024] 3. The method guarantees the safe, stable and economic operation of the unit, reduces the downtime and economic loss caused by the sticking fault, and reduces the replacement and maintenance cost caused by equipment damage. DETAILED DESCRIPTION

[0025] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with embodiments of the present application, and do not constitute a limitation on the present application. In the drawings:

[0026] Figure 1 It is a valve shaft processing structure schematic diagram of the processing method for the intermediate-pressure steam valve sticking fault of a steam turbine.

[0027] Figure 2 It is a special-shaped tool processing structure schematic diagram of the processing method for the intermediate-pressure steam valve sticking fault of a steam turbine. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] It should be noted that the words "front", "back", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings, and the words "inner" and "outer" refer to the directions towards or away from the geometric center of a specific component.

[0030] The processing method for the intermediate-pressure steam valve sticking fault of a steam turbine includes:

[0031] Device design processing: the valve shaft end face of the mechanical execution end of the main steam valve in the steam turbine is turned and milled to open an inner hexagonal device; at the same time, a lifting ring hole is machined on the valve shaft end face, professional measuring tools are used to detect the deviation of two points symmetrically in the circular shaft direction of the valve shaft, and the deviation value is required to be not more than 0.04mm, to ensure that the valve shaft basic state meets the subsequent processing and use requirements; a special-shaped opening tool is made to match the inner hexagonal device of the valve shaft, the tool material is selected to be 40Cr, and needs to be quenched and tempered to ensure the strength and durability of the tool to meet the force requirement in the valve opening and closing process; a connecting device for connecting the valve shaft and the special-shaped opening tool is prepared to ensure that the connecting structure is stable and can effectively transmit external force; at the same time, a chain hoist is prepared, which will cooperate with the external lifting point to realize the driving of the valve opening and closing.

[0032] Assembly connection: the machined valve shaft and the completed special-shaped opening tool are combined and installed through the connecting device to ensure that the inner hexagonal device and the special-shaped opening tool are accurately matched without loosening or deviation; after installation, the chain hoist is connected with the lifting ring hole on the valve shaft end face, and at the same time, the bridge crane in the steam turbine workshop is determined as the external driving lifting point, so that the chain hoist is hung below the lifting point of the bridge crane to form a complete external driving system.

[0033] Fault handling operation: when the main steam valve of the steam turbine appears to be stuck, the above-mentioned assembled processing system is started: by adjusting the lifting point position of the bridge crane, cooperating with the stretching and contracting action of the chain hoist, and applying stable external force to drive the valve shaft movement, the flexible opening and closing of the main steam valve is realized, the sticking problem is solved, and the whole operation process can avoid the problems of mechanical execution mechanism deformation, shaft end sealing failure and other problems caused by traditional external intervention, to ensure the safety and controllability of valve opening and closing action.

[0034] Maintenance prompt: pay special attention to the fault points prone to sticking of the valve, such as the gap between the door shaft and the door body, the contact surface between the door shaft and the bushing, the material state of the door shaft and the sleeve, and do a good job of daily inspection and record; carry out valve activity test regularly to find out potential sticking hidden trouble in time; once the valve appears to be stuck or other abnormal conditions, the relevant operation should be stopped immediately, the fault reason is found out and the fault is eliminated by using the method, to avoid the expansion of the fault and cause major accidents.

[0035] As shown in Figure 1 and Figure 2 , in specific use, taking the sticking fault handling of the main steam valve of the power plant steam turbine as an example, the implementation steps are as follows:

[0036] 1, Confirm the turbine is in shutdown or safety condition, cut off the power source of the MP steam valve, measure the bending of the valve shaft, the deviation of two points in the same direction of the circle should be less than 0.04mm, then turn and mill the end face of the valve shaft, make the special open tool with 40Cr material and complete the quenching and tempering, prepare the connecting device and chain hoist.

[0037] 2, Connect the special open tool and the valve shaft accurately through the connecting device, check the stability of the connection, connect the chain hoist and the valve shaft, hang the chain hoist on the lifting point of the bridge crane in the turbine workshop, adjust the position of the lifting point to make the chain hoist in the vertical force state, ensure that the direction of the driving force is consistent with the direction of the valve shaft movement.

[0038] 3, Operate the bridge crane to keep the lifting point stable, slowly adjust the extension of the chain hoist, apply external force to drive the valve shaft movement, observe the opening and closing state of the MP steam valve: if the valve is stuck and cannot be closed, pull down the valve shaft through the chain hoist to achieve the closing action; if the valve is stuck and cannot be opened, lift the valve shaft through the chain hoist to achieve the opening action, the whole process is stable and controllable, there is no mechanical actuator deformation or shaft end leakage phenomenon.

[0039] 4, After the fault handling is completed, the valve is tested according to the requirements of the manufacturer, the opening and closing of the valve is confirmed, the gap between the door shaft and the door body, the contact surface between the door shaft and the bushing and other key parts are checked, and the records are made; follow-up maintenance and activity test of the valve are carried out regularly to ensure long-term stable operation of the equipment.

[0040] It should be noted that, in the present document, relational terms such as first and second and the like can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0041] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to the details of the embodiments described, since numerous modifications and substitutions can be made without departing from the spirit and scope of the present application, which is defined by the appended claims and their equivalents.

Claims

1. A method of handling a sticking fault of an intermediate pressure steam valve in a steam turbine, characterized in that, The method comprises the following steps: (I) Device design and processing: turning and milling the valve shaft end face of the mechanical actuator of the intermediate pressure main steam valve of the steam turbine, and opening an inner hexagonal device; meanwhile, a lifting eye hole is processed on the valve shaft end face; a special-shaped opening tool is made to match the inner hexagonal device of the valve shaft, which meets the force requirement in the valve opening and closing process; a connecting device for connecting the valve shaft and the special-shaped opening tool is prepared to ensure that the connecting structure is stable and can effectively transmit external force; at the same time, a chain hoist is prepared, which will cooperate with the external lifting point to realize the driving of the valve opening and closing. (II) Assembly and connection: the processed valve shaft and the completed special-shaped opening tool are combined and installed through the connecting device to ensure that the inner hexagonal device and the special-shaped opening tool are accurately matched without loosening or deviation; after installation, the chain hoist is connected with the lifting eye hole on the valve shaft end face, and the bridge crane in the steam turbine plant is determined as the external driving lifting point, so that the chain hoist is hung below the lifting point of the bridge crane to form a complete external driving system. (III) Fault handling operation: when the intermediate pressure main steam valve of the steam turbine appears to be stuck, the above-mentioned assembled treatment system is started: the lifting point position is adjusted by operating the bridge crane, the chain hoist is stretched and contracted, stable external force is applied to drive the valve shaft to move, the flexible opening and closing of the intermediate pressure main steam valve is realized, the sticking problem is solved, the whole operation process can avoid the problems of mechanical actuator deformation and shaft end seal failure caused by traditional external force intervention, and ensures the safety and controllability of valve opening and closing action. (IV) Maintenance prompt: pay special attention to the sticking fault points of the valve, and do well in daily inspection and record; carry out valve activity test regularly to find potential sticking hidden trouble in time; once the valve appears to be stuck or other abnormal conditions, the related operation should be stopped immediately, the fault reason is found out and the fault is eliminated by using the method to avoid the expansion of the fault and cause major accidents.

2. A method of handling a stuck open MP valve fault in a steam turbine according to claim 1, characterized in that: The deviation of the two points symmetrically arranged in the circular shaft direction of the valve shaft is detected by using professional measuring tools, and the deviation value is required to be not more than 0.04mm, so as to ensure that the valve shaft basic state meets the subsequent processing and use requirements.

3. A method of handling a stuck open MP valve fault in a steam turbine as claimed in claim 1, wherein: The special-shaped opening tool matched with the inner hexagonal device of the valve shaft is made of 40Cr and needs to be quenched and tempered to ensure the strength and durability of the tool.

4. The method of claim 1, wherein: The sticking fault points of the valve include but are not limited to the gap between the door shaft and the door body, the contact surface between the door shaft and the bushing, and the material state of the door shaft and the sleeve.

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