Method for replacing steam turbine rotor

Abstract

The present invention provides a method for replacing a steam turbine rotor, comprising steps S1 and S4. Step S1: removing the old rotor from the elliptical bearing, placing a spacer between the corresponding split surfaces at each end of the elliptical bearing shell, so that the shape formed by the two elliptical bearing shells and the spacer is close to a circle; Step S2: installing the elliptical bearing shells together with the spacer on machining equipment, and processing the elliptical bearing shells; Step S3: reinstalling the two elliptical bearing shells on the elliptical bearing; Step S4: installing the new rotor to be installed on the elliptical bearing. This method uses spacers to combine the elliptical bearing shells into a shape close to a circle, and then processes the elliptical bearing shells using machining equipment. This method makes the processing more precise and efficient. The size of the processed elliptical bearing shells can more accurately meet the size requirements for matching the rotor to be installed, greatly improving the efficiency of replacing the new turbine rotor, while ensuring safety and increasing the life of the elliptical bearing shells.

Description

Technical Field

[0001] The present invention relates to the field of steam turbines, and in particular to a method for replacing a steam turbine rotor. Background Art

[0002] The function of the pneumatic feedwater pump equipment in a nuclear power plant is to provide the evaporator with the required flow of feedwater, and work with the feedwater system to maintain the evaporator liquid level at a normal level, thereby ensuring the safe and stable operation of the nuclear power plant system. The role it plays is crucial to the safe and stable operation of the nuclear power plant. However, in a series of full-life processes such as manufacturing, installation, operation and maintenance, especially in the early manufacturing and installation periods, the attention paid to it is far less than that paid to large and important equipment such as the main steam turbine and generator. As a result, the deviation between the pneumatic feedwater pump equipment and the design value during manufacturing, and the deviation between the sizes of different pneumatic feedwater pump equipment groups cannot be traced back to the relevant recorded values.

[0003] Unknown deviations between different pneumatic feedwater pump groups, and between operating equipment and design baseline values, create significant challenges in replacing critical components like rotors. Especially given the tightly controlled overhaul schedules of nuclear power plants, conventional methods cannot be used to address these deviations within the required timeframe. Consequently, missed replacement windows for components like rotors lead to project failures and the inability to implement related equipment management measures as planned. This creates safety risks for the safe and stable operation of pneumatic feedwater pump equipment and nuclear power plant systems.

[0004] During the replacement of aging rotors, significant discrepancies in shaft diameter, length, and other dimensions are often observed between the new rotor and the old rotor being replaced. This discrepancy in shaft diameter leads to discrepancies in the clearance between the shaft and the bearing shell, which can cause problems: a smaller clearance can lead to abnormally high bearing operating temperatures, resulting in localized overheating.

[0005] Conventional solutions and treatment measures are: using conventional manual scraping to repair the elliptical bearing, but there are problems:

[0006] The problem of deviation in the shaft diameter of the new and old rotors discovered during the inspection resulted in the rotor's elliptical bearing and elliptical bushings requiring much more repair work than would be done through conventional overhauls. Conventional manual scraping repair methods, which involve low scraping efficiency, also pose a major problem. The main issue with manual scraping is that the scraped dimensions along the axial and radial surfaces of the elliptical bushings are highly inconsistent, ultimately leaving local high points (or raised points) on the bearing bushing surface. This means increased loads at these high points and insufficient lubrication flow, leading to hot spots in the high-point areas during operation. These hot spots on the elliptical bushings cause the bearing temperature to rise, reaching the bearing temperature alarm value or even further increasing to the threshold that triggers a tripping device, posing a significant safety hazard to daily unit operation.

[0007] Therefore, it is necessary to develop an efficient and more reliable method for installing the new rotor to ensure that the newly installed rotor works well with the elliptical bearing of the original elliptical bearing. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide an improved method for replacing a steam turbine rotor in view of the above-mentioned defects in the related art.

[0009] The technical solution adopted by the present invention to solve the technical problem includes: providing a method for replacing a steam turbine rotor, comprising:

[0010] Step S1: removing the old rotor from the elliptical bearing, and removing the two split elliptical bearing shells from the elliptical bearing, wherein the two split surfaces of one elliptical bearing shell are respectively arranged opposite to the two split surfaces of the other elliptical bearing shell, and a spacer is arranged between the two opposing split surfaces, so that the shape formed by the two elliptical bearing shells and the spacer is close to a circle;

[0011] Step S2: installing the elliptical bearing together with the spacer block on a machining device to process the elliptical bearing;

[0012] Step S3: After the elliptical bearing is processed, the spacer is removed from the elliptical bearing, and the two elliptical bearings are mounted back on the elliptical bearing;

[0013] Step S4: Install the new rotor to be installed on the elliptical bearing.

[0014] Preferably, step S1 comprises: determining the diameter d of the rotor shaft to be installed;

[0015] Step S1 also includes: determining the side clearance required for the rotor shaft with a diameter of d to operate in a circular bearing with an inner diameter of D Required head clearance C d2=D-d, where D is equal to the major axis of the inner ellipse formed by the two elliptical bearings in step S1, and the side clearance C d1 The top clearance C is the clearance between the radial side of the rotor shaft and the inner side of the circular bearing. d2 It is the gap between the top side of the rotor shaft in the radial direction and the inner side of the circular bearing;

[0016] Step S1 also includes: determining the minimum side clearance C required between the rotor shaft and the elliptical bearing when the rotor runs on the elliptical bearing. d1min , the minimum required top clearance C d2min , wherein the top clearance is the clearance between the side surface of the rotor shaft and the inner side of the elliptical bearing in the direction of the minor axis of the ellipse formed by the two elliptical bearings, and the side clearance is the clearance between the side surface of the rotor shaft and the inner side of the elliptical bearing in the direction of the major axis of the ellipse formed by the two elliptical bearings;

[0017] In the direction of the short axis of the ellipse formed by the two elliptical bearings, the size of the pad is Δh, wherein, if C d2 Less than C d2min And C d1 Less than C d1min , then Δh=2×C d1min -C d2min .

[0018] Preferably, in the direction of the major axis of the ellipse formed by the two elliptical bearings, the size of the pad is equal to the thickness of the elliptical bearings.

[0019] Preferably, if C d2 Greater than C d2min , then Δh=2×C d1min -C d2 .

[0020] Preferably, if C d1 Greater than C d1min , then Δh=2×C d1 -C d2min .

[0021] Preferably, step S3 further comprises: after removing the pad from the elliptical bearing, measuring the dimension A of the inner side of the bearing in the direction of the minor axis of the ellipse and the dimension B in the direction of the major axis of the ellipse when the two elliptical bearings are combined into an ellipse, if the value of A is within (d+C d1min )~(d+C d2max ) and the B value is within (d+2C d2min )~(d+2C d2max ) range, then the elliptical bearing shell is mounted back on the elliptical bearing; otherwise, repeat step S2 until the value of A is within (d+C d1min )~(d+Cd2max ) and the B value is within (d+2C d2min )~(d+2C d2max ) range.

[0022] Preferably, the pad is a rectangular pad.

[0023] Preferably, in the direction of the major axis of the ellipse formed by the two elliptical bearings, the size of the pad is equal to the size of the split surface of the elliptical bearing.

[0024] Preferably, in step S2, the processing of the elliptical bearing includes turning.

[0025] Preferably, in step S2, the machining equipment is a lathe.

[0026] The implementation of the technical solution of the present invention has at least the following beneficial effects: the method for installing the turbine rotor of the nuclear power plant feed water pump uses a spacer to combine the elliptical bearing into a shape close to a circle, and then uses machining equipment to process the elliptical bearing, which makes the processing more precise and efficient. The size of the processed elliptical bearing can more accurately meet the size requirements of the rotor to be installed, and then the rotor to be installed is installed, which greatly improves the efficiency of replacing the new rotor for the turbine, while ensuring the safety of the operation of the turbine after the new rotor is installed, and improving the life of the elliptical bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is an orthographic projection view of an elliptical bearing bush of the steam turbine rotor replacement method of the present invention.

[0029] Figure 2 It is an orthographic projection view of two elliptical bearings combined into an elliptical shape in the method for replacing a steam turbine rotor of the present invention.

[0030] Figure 3 It is an orthographic projection view of a spacer provided between two elliptical bearing shells in the method for replacing a steam turbine rotor according to the present invention.

[0031] The numbers in the figure indicate: elliptical bearing 1, split surface 11, and pad 2. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. It should be understood that if the directions or positional relationships indicated by "upper", "lower", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom" and the like appear in the text, they are based on the directions or positional relationships shown in the drawings, and are constructed and operated in a specific direction. They are only for the convenience of describing the present technical solution, and do not indicate that the devices or elements referred to must have a specific direction. Therefore, they should not be understood as limiting the present invention. It should also be noted that unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed", "set" and the like appear in the text, they should be understood in a broad sense. For example, they can be fixedly connected, detachably connected, or integrated; they can be directly connected, or indirectly connected through an intermediate medium, and can be internal communication between two elements or an interactive relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0034] A method for replacing a steam turbine rotor in one embodiment of the present invention includes:

[0035] Step S1: Remove the old rotor from the elliptical bearing, and remove the two split elliptical bearing shells 1 from the elliptical bearing, see Figure 1 Each elliptical bearing 1 includes two split surfaces 11 respectively arranged at both ends, see Figure 3The two split surfaces 11 of one elliptical bearing 1 are respectively arranged opposite to the two split surfaces 11 of the other elliptical bearing 1, and a spacer 2 is arranged between the two oppositely arranged spacers 11, that is, two spacers 2 are arranged in total, so that the shape formed by the two elliptical bearings 1 and the spacers 2 is close to a circle, so as to facilitate processing on machining equipment, because it is relatively easy for various machining equipment to process circular workpieces, but it is difficult or even impossible to process elliptical workpieces. For example, a lathe is a machine tool that mainly uses a turning tool to turn a rotating workpiece. After the circular workpiece is installed on the lathe, it rotates, and the turning tool processes the rotating workpiece. It can easily process circular workpieces, but it is almost impossible to process elliptical workpieces;

[0036] Step S2: installing the elliptical bearing 1 together with the spacer 2 on a machining device to process the elliptical bearing 1;

[0037] Step S3: After the elliptical bearing shell 1 is processed, the spacer 2 is removed from the elliptical bearing shell 1, and the two elliptical bearing shells 1 are mounted back on the elliptical bearing;

[0038] Step S4: Install the new rotor to be installed on the elliptical bearing.

[0039] The method for installing the turbine rotor of the nuclear power plant feed water pump uses a gasket 2 to combine the elliptical bearing 1 into a shape close to a circle, and then uses machining equipment to process the elliptical bearing 1. The processing is more precise and efficient. The size of the processed elliptical bearing 1 can more accurately meet the size requirements of the rotor to be installed, and then the rotor to be installed is installed, which greatly improves the efficiency of replacing the new rotor of the turbine, while ensuring the safety of the operation of the turbine after the new rotor is installed, and improving the life of the elliptical bearing 1.

[0040] Preferably, step S1 comprises: determining the diameter d of the rotor shaft to be installed;

[0041] Preferably, step S1 further comprises: determining the side clearance required for the rotor shaft with a diameter of d to operate in a circular bearing with an inner diameter of D Required head clearance C d2 =D-d, where D is equal to the major axis of the inner ellipse formed by the two elliptical bearings 1 in step S1, and the side clearance C d1 The top clearance C is the clearance between the radial side of the rotor shaft and the inner side of the circular bearing. d2 It is the gap between the top side of the rotor shaft in the radial direction and the inner side of the circular bearing;

[0042] For elliptical pad bearings, the side clearance and top clearance are generally calculated by the bearing manufacturer based on the operating parameters:

[0043] Side clearance control range: C d1min ~C d1max, where C d1min is the minimum value of the side clearance, C d1max is the maximum value of the side clearance;

[0044] Top gap control range: C d2min ~C d2max , where C d2min is the minimum value of the top gap, C d2max is the maximum value of the top gap.

[0045] In order to ensure the bearing life is as long as possible, the side clearance and top clearance are selected to have the minimum value C d1min 、C d2min As the final target value of the bearing repair, step S1 further includes: determining the minimum value C of the side clearance required between the rotor shaft and the elliptical bearing 1 when the rotor runs on the elliptical bearing. d1min , the minimum required top clearance C d2min , where for an elliptical bearing, the top clearance is the clearance between the side of the rotor shaft and the inner side of the elliptical bearing 1 in the direction of the minor axis of the ellipse formed by the two elliptical bearing shells 1, and the side clearance is the clearance between the side of the rotor shaft and the inner side of the elliptical bearing shell 1 in the direction of the major axis of the ellipse formed by the two elliptical bearing shells 1;

[0046] See also Figure 3 , in the direction of the minor axis of the ellipse formed by the two elliptical bearings 1, the size of the pad 2 (i.e. the thickness of the pad 2) is Δh, where if C d2 Less than C d2min And C d1 Less than C d1min , then Δh=2×C d1min -C d2min , so that the shape of the elliptical bearing shells 1 and the pads 2 of the two elliptical bearings is as close to the standard circle as possible to facilitate processing.

[0047] See also Figure 3 In the direction of the major axis of the ellipse formed by the two elliptical bearings 1, the size of the pad 2 (ie the width of the pad 2) is equal to the thickness of the elliptical bearing 1.

[0048] If C d2 Within normal range and greater than C d2min , then Δh=2×C d1min -C d2 , so that the shape of the elliptical bearing shells 1 and the pads 2 of the two elliptical bearings is as close to the standard circle as possible to facilitate processing.

[0049] If C d1 Within normal range and greater than C d1min , then Δh=2×C d1 -C d2min, so that the shape of the elliptical bearing shells 1 and the pads 2 of the two elliptical bearings is as close to the standard circle as possible to facilitate processing.

[0050] Method for dealing with the problem of excessive clearance of elliptical bearing 1: The following steps can be used to deal with the problem of excessive clearance of elliptical bearing 1, which can effectively ensure that the clearance of each part of the bearing surface and the axial direction of the elliptical bearing 1 is uniform. Select the height of the pad 2: round off the data calculated by the above method to facilitate the selection of a suitable standard pad 2, such as:

[0051] C d1 =0.28~0.30mm

[0052] C d2 =0.27mm (the actual measured data, the gap is just within the design requirement range of 0.2 ~ 0.3mm)

[0053] Calculate Δh = 2 × 0.28 - 0.27 = 0.29 mm.

[0054] Preferably, step S3 further includes: Figure 2 After removing the pad 2 from the elliptical bearing 1, with the split surfaces 11 of the two elliptical bearings 1 facing each other and forming an ellipse, measure the dimension A of the inner side of the bearing in the direction of the minor axis of the ellipse and the dimension B in the direction of the major axis of the ellipse. If the value of A is within (d+C d1min )~(d+C d2max ) and the B value is within (d+2C d2min )~(d+2C d2max ) range (ideally it should be greater than and close to (d+2C d2min ), then install the elliptical bearing 1 back on the elliptical bearing; otherwise, repeat step S2 until the value of A is within (d+C d1min )~(d+C d2max ) and the B value is within (d+2C d2min )~(d+2C d2max ) range before installing the elliptical bearing shell 1 back onto the elliptical bearing.

[0055] See also Figure 3 , pad 2 is a standard rectangular pad to ensure the accuracy of the pad height.

[0056] See also Figure 3 In the direction of the major axis of the ellipse formed by the two elliptical bearings 1, the size of the pad 2 is equal to the size of the split surface 11 of the elliptical bearing 1, so that the shape formed by the two elliptical bearings 1 and the pad 2 is as close to the standard circle as possible.

[0057] Preferably, in step S2 , the processing performed on the elliptical bearing shell 1 includes turning.

[0058] Preferably, in step S2, the machining equipment is a lathe.

[0059] The traditional method of manually scraping and repairing the elliptical bearing 1 is avoided, and a machining process is adopted to ensure that the axial and circumferential dimensions of the processed bearing are uniform and free of high spots, thus eliminating the problem of high local temperature caused by high spots during the operation of the turbine rotor;

[0060] The thickness of the pad 2 required for turning is calculated based on the actual measurement data of the elliptical bearing 1 and the clearance requirements. The value in the direction to be processed is set according to the minimum design clearance to ensure that the remaining operating life of the bearing is as long as possible.

[0061] Select a standard cubic-shaped spacer 2 to ensure the height of the spacer is accurate.

[0062] The method for installing the turbine rotor of the feed water pump of the nuclear power plant uses a pad 2 to combine the elliptical bearing 1 into a shape close to a circle, and then uses machining equipment to process the elliptical bearing 1. The processing is more precise and efficient. The size of the processed elliptical bearing 1 can more accurately meet the size requirements of the rotor to be installed, and then the rotor to be installed is installed, which greatly improves the efficiency of the work of replacing the turbine rotor and eliminates the problems of low processing efficiency, long time consumption, uneven processing, and unsatisfactory operating status after processing brought about by the previous rotor installation method. At the same time, it ensures the safety of the operation of the turbine after the new rotor is installed. It is efficient, safe and reliable, and the remaining life of the elliptical bearing 1 is retained to the maximum extent. Combined with the actual elliptical bearing 1 measurement size status and the elliptical bearing 1 design size requirements, the size of the pad 2 required for processing is determined, and a standard cubic pad 2 is used to ensure the accuracy of the pad 2, and then the pad 2 is turned according to the calculated size.

[0063] In terms of economic benefits, if the conventional method of manually machining the elliptical bearing 1 and then installing the new rotor is used, it would take approximately five days, during which time the electric feedwater pump would need to be started. The electric feedwater pump consumes 960,000 kilowatt-hours of electricity in five days, and the nuclear power plant unit generates approximately 640,000 kilowatt-hours less electricity than the steam-driven pump. The steam turbine rotor installation method for the nuclear power plant feedwater pump using this technical solution not only avoids the aforementioned direct losses, but more importantly, ensures the normal and safe operation of the equipment, thereby providing a safety guarantee for the safe operation of the unit.

[0064] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications, combinations, and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the claims.

Claims

1. A method for replacing a steam turbine rotor, characterized in that: include: Step S1: remove the old rotor from the elliptical bearing, and remove the two split elliptical bearing shells (1) of the elliptical bearing from the elliptical bearing, wherein each of the elliptical bearing shells (1) includes two split surfaces (11) respectively arranged at both ends, and the two split surfaces (11) of one elliptical bearing shell (1) and the two split surfaces (11) of the other elliptical bearing shell (1) are respectively arranged opposite to each other, and a spacer (2) is arranged between the two oppositely arranged split surfaces (11), so that the shape formed by the two elliptical bearing shells (1) and the spacer (2) is close to a circle; Step S2: installing the elliptical bearing (1) together with the pad (2) on a machining device, and machining the elliptical bearing (1); Step S3: After the elliptical bearing bush (1) is processed, the pad (2) is removed from the elliptical bearing bush (1), and the two elliptical bearing bushes (1) are mounted back on the elliptical bearing; Step S4: installing the new rotor to be installed on the elliptical bearing; Step S1 includes: determining the diameter d of the rotor shaft to be installed; Step S1 also includes: determining the side clearance required for the rotor shaft with a diameter of d to operate in a circular bearing with an inner diameter of D Required head clearance C d2 =D-d, where D is equal to the major axis of the inner ellipse formed by the two elliptical bearings (1) in step S1, and the side clearance C d1 The top clearance C is the clearance between the radial side of the rotor shaft and the inner side of the circular bearing. d2 It is the gap between the top side of the rotor shaft in the radial direction and the inner side of the circular bearing; Step S1 also includes: determining the minimum value C of the side clearance required between the rotor shaft and the elliptical bearing (1) when the rotor runs on the elliptical bearing d1min , the minimum required top clearance C d2min , wherein the top gap is the gap between the side surface of the rotor shaft and the inner side of the elliptical bearing (1) in the direction of the short axis of the ellipse formed by the two elliptical bearings (1), and the side gap is the gap between the side surface of the rotor shaft and the inner side of the elliptical bearing (1) in the direction of the long axis of the ellipse formed by the two elliptical bearings (1); In the direction of the short axis of the ellipse formed by the two elliptical bearings (1), the size of the pad (2) is Δh, wherein, if C d2 Less than C d2min And C d1 Less than C d1min , then Δh=2×C d1min -C d2min .

2. The method for replacing a steam turbine rotor according to claim 1, wherein: In the direction of the major axis of the ellipse formed by the two elliptical bearing bushes (1), the size of the pad (2) is equal to the thickness of the elliptical bearing bushes (1).

3. The method for replacing a steam turbine rotor according to claim 1, wherein: If C d2 Greater than C d2min , then Δh=2×C d1min -C d2 .

4. The method for replacing a steam turbine rotor according to claim 1, wherein: If C d1 Greater than C d1min , then Δh=2×C d1 -C d2min .

5. The method for replacing a steam turbine rotor according to claim 1, wherein: Step S3 also includes: after removing the pad (2) from the elliptical bearing (1), in a state where the two elliptical bearings (1) are combined into an ellipse, measuring the dimension A of the inner side of the bearing in the direction of the minor axis of the ellipse and the dimension B in the direction of the major axis of the ellipse. If the value of A is within (d+C d1min )~(d+C d2max ) and the B value is within (d+2C d2min )~(d+2C d2max ) range, the elliptical bearing (1) is mounted back on the elliptical bearing; otherwise, step S2 is repeated until the value of A is within (d+C d1min )~(d+C d2max ) and the B value is within (d+2C d2min )~(d+2C d2max ) range.

6. The method for replacing a steam turbine rotor according to any one of claims 1 to 5, characterized in that: The cushion block (2) is a rectangular cushion block.

7. The method for replacing a steam turbine rotor according to any one of claims 1 to 5, characterized in that: In the direction of the major axis of the ellipse formed by the two elliptical bearing bushes (1), the size of the pad (2) is equal to the size of the split surface (11) of the elliptical bearing bushes (1).

8. The method for replacing a steam turbine rotor according to any one of claims 1 to 5, characterized in that: In the step S2, the processing of the elliptical bearing (1) includes turning.

9. The method for replacing a steam turbine rotor according to any one of claims 1 to 5, characterized in that: In step S2, the machining equipment is a lathe.

Images