Patent Application
20070296964
More complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the following drawings.
a) and 5(b) are schematic diagrams for explaining an operation method of the present invention when the screw device as well as the video scope of the inspection apparatus in the first embodiment are inserted in the narrow pathway of the steam turbine.
Referring now to the drawings, where like reference numerals designate identical or corresponding components throughout the several views, preferred embodiments of the present invention will be described in detail.
The steam turbine introduces the steam generated by a steam generator to blades 11 established on a rotor and to nozzles 12 established on a stator, thereby rotating the rotor to drive an electric power generator. In such a configuration, the passages where the steam passes through the blades 11 and nozzles 12 constitute narrow pathways that to be inspected.
The inspection apparatus of the present invention is configured by a video scope (video probe) 14 having a camera (with a search light) and an articulating portion 16 at its end, and a screw device 15 in which the video scope 14 is inserted for guiding the video scope 14 as it advances forward, and a video monitor 17 for controlling the direction of the end of the video scope 14 as well as displaying the images from the video scope 14.
The video monitor 17 is configured by a display 17a for displaying the images captured by the camera 13, and an operating unit 17b for controlling the direction of the end of the video scope 14. The display 17a of the video monitor 17 is, for example, a liquid crystal display (LCD), and the operating unit 17b of the video monitor 17 is, for example, a joystick.
The articulating portion 16 at the end of the video scope 14 moves in response to the maneuver of the operating unit 17b of the video monitor 17, thereby changing the direction of the end of the video scope 14. The screw device 15 is formed in a tube-like shape, and when it is inserted in the narrow pathway in the steam turbine, and applied with a rotational force, it advances forward through the narrow pathway while engaging with the surfaces of the blades 11 and nozzles 12 within the steam turbine. The video scope 14 moves through the screw device 15 where it is guided through the narrow pathway of the steam turbine until it reaches the area to be inspected.
In other words, the video scope 14 moves through the narrow pathway of the steam turbine while being supported by the screw device 15. Then, the video scope 14 protrudes from the end of the screw device 15, captures the images of the surfaces of the blades 11 and nozzles 12 by the camera 13 mounted at the end of the video scope 14, and sends the captured video signals to the video monitor 17.
Further, the articulating portion 16 at the end of the video scope 14 is driven by the operating unit 17b of the video monitor 17, where the direction of the end of the video scope 14 is changed. By changing the direction of the end of the video scope 14, the images at each orientation of the surfaces of the blades 11 and nozzles 12 can be captured by the camera 13. Moreover, the moving direction of the screw device 15 can be determined by the direction of the end of the video scope 14.
Namely, when the screw device 15 is inserted into the narrow pathway of the steam turbine and applied with the rotational force, it moves through the narrow pathway while contacting with the surfaces of the blades 11 and nozzles 12 within the steam turbine. The moving direction during this operation is determined by the direction of the end of the video scope 14 that is inserted in the narrow pathway.
Next, the screw device 15 will be described in detail.
An end 20 is formed with a bellows shape or an accordion-like structure and is made of flexible material. For example, the end 20 is formed of an extension spring. The reason that the end 20 is formed of such flexible material is that the end of the video scope 14 to be inserted through the screw device 15 can easily select the moving direction of the screw device 15.
When determining the moving direction of the screw device 15, the video scope 14 takes the lead and the screw device 15 follows the video scope 14. However, there are times when the video scope 14 has to be bent in the direction desired to proceed. Since the force to bend the video scope 14 is small, if the end of the screw device 15 is made of hard material, it will not be able to bend the video scope 14 when it is necessary. For this reason, the end of the screw device 15 is made of flexible material such as a stretchable (extension) spring. Further, the main body 18 and the end 20 are connected by a joint 21. The joint 21 is also made of flexible material such as rubber.
Next, the movement of the articulating portion 16 formed at the end of the video scope 14 will be described in detail.
The direction of the end of the video scope 14 is changed by driving the articulating portion 16 which is regulated by the operating unit 17b of the video monitor 17 shown in
Next, the method of operating the inspection apparatus of the present invention will be described in detail.
The exterior of each low pressure turbine 34a, 34b, and 34c is covered by turbine external rooms 35a, 35b and 35c, respectively. The turbine external rooms 35a, 35b and 35c are also called external casings, each being structured in the shape of a hollow cylinder. The turbine external rooms 35a, 35b and 35c achieve the function of covering a turbine rotor 37 as well as turbine internal rooms 36a, 36b and 36c, and are individually structured by a top member and a bottom member where the top member is removed during inspection. In
Further, manholes 38a, 38b and 38c are established on a disc surface of the turbine external rooms 35a, 35b and 35c, respectively, in an axial direction. The manholes 38a, 38b and 38c are holes established in the axial direction of the turbine external rooms 35a, 35b and 35c where they are closed during the normal operation. These manholes 38a, 38b, and 38c are holes for looking inside the turbines during inspection without removing the turbine external rooms 35a, 35b and 35c to check the condition up to the final blade.
The turbine internal rooms 36a, 36b and 36c are also called internal casings, and cover the blades 11 and the rotor 37. Similar to the turbine external rooms 35a, 35b and 35c, each of the turbine internal room is constructed by a top member and a bottom member, where several hand holes 39 are established thereon. The hand holes 39 are holes established on the side of each of the turbine internal rooms 36a, 36b and 36c, and similar to the manholes 38a, 38b, and 38c, they are holes for looking inside the turbine internal rooms 36a, 36b and 36c to check the condition inside the turbines as well as the blades and nozzles.
Further, the last turbine 40 of each of the low pressure turbines 34a, 34b and 34c has the longest blade, and the flow of the steam is introduced to the center of each of the low pressure turbines 34a, 34b and 34c the shortest blade is located, where it provides work to the blades 11 on both sides in the axial direction and expands while heading toward the direction of the final turbines 40 on both sides to be exhausted therefrom.
For the above structured steam turbine, when the turbine external rooms 35a, 35b and 35c are removed leaving only the turbine internal rooms 36a, 36b and 36c, the screw device 15 is inserted through the hand holes 39 established on the side of each of the turbine internal rooms 36a, 36b and 36c or through the final turbines 40. On the other hand, when the turbine external rooms 35a, 35b and 35c are assembled to the steam turbine, the screw device 15 is inserted through the manholes 38a, 38b and 38c established in the axial direction of the turbine external rooms 35a, 35b and 35c.
For example, as shown in
In this condition, the inspector checks the images on the display 17a of the video monitor 17 received from the camera showing the areas surrounding the camera 13. The inspector drives the articulating portion 16 through the operating unit 17b to select an area to be inspected. Since the direction of the end of the video scope 14 changes by the movement of the articulating portion 16, the location of the camera 13 changes as well. Accordingly, the inspector can select an area to be inspected while looking at the image on the display 17a of the video monitor 17.
When the area to be inspected is determined, the end of the video scope 14 is directed towards the inspection area by moving the articulating portion 16. Then, the screw device 15 is rotated. When the rotational force is applied to the screw device 15, the helical notches 19 on the main body 18 engage with the surfaces of the blade 11 and nozzle 12, which are the internal structural members. The driving force for moving towards the narrow pathway of the steam turbine is created by the friction created by contacting the helical notches 19 with the blade 11 and nozzle 12. Thus, the screw device 15 moves forward through the narrow pathway while being guided by the end of the video scope 14 that is projected from the end of the screw device 15. As a consequence, the screw device 15 advances in the direction of the end of the video scope 14 toward the inspection area.
a) and 5(b) schematically show the operation method of the present invention when the screw device 15 is inserted into the narrow pathway of the steam turbine.
Under the condition where the end 20 of the screw device 15 is inserted in the narrow pathway located between the blades 11b1 and 11b2, the inspector manually sends the video scope 14 so that it projects from the end 20 of the screw device 15. Then, the inspector determines the area to be inspected while monitoring the images from the camera 13 shown on the display 17a of the video monitor 17.
For example, if the narrow pathway located between the nozzles 12b1 and 12b2 is selected as the area to be inspected, the inspector controls the articulating portion 16 through the operating unit 17b on the video monitor 17 to direct the end of the video scope 14 towards the narrow pathway, and manually sends the video scope 14. As a consequence, the end of the video scope 14 moves into the narrow pathway located between the nozzles 12b1 and 12b2, i.e., the inspection area, as shown in
Then, the inspector manually rotates the screw device 15. When the rotational force is applied to the screw device 15, the helical notches 19 on the main body 18 engages with the surfaces of the blade 11 and nozzle 12. Thus, the driving force is produced in the direction of the end of the video scope 14 by the frictional force created by the engagement with the blade 11 and nozzle 12. Accordingly, the screw device 15 moves closer to the narrow pathway located between the nozzle 12b1 and 12b2, i.e., the inspection area, as shown in
In the situation of
According to the first embodiment of the present invention, since the video scope 14 is supported by the screw device 15 and can advance in the desired direction while selecting the narrow pathway of the steam turbine to be inspected, it is possible to acquire images of the desired areas to be inspected on the display 17a of the video monitor 17. Therefore, visual inspection of the blade and nozzle, which are the internal structural members, can be conducted without disassembling the steam turbine.
Next, the second embodiment of the present invention will be explained in detail.
The screw device driver 22 is formed of a drive wheel 23, an auxiliary wheel 24, a gear 25, and a drive motor 26 which drives the drive wheel 23 through the gear 25. When the drive wheel 23 is driven through the gear 25 by the drive motor 26, the drive wheel 23 and auxiliary wheel 24, which contact the outer surface of the screw device 15, apply a rotational force to the screw device 15. In other words, the screw device 15 is held between the drive wheel 23 and auxiliary wheel 24, where the rotational force is applied to the screw device 15 by rotating the drive wheel 23. It should be noted that although the screw device 15 rotates, the video scope 14 inserted in the screw device 15 will not rotate.
When the rotational force is applied to the screw device 15 by the screw device driver 22, as mentioned above, the helical notches 19 on the main body 18 contact the surfaces of the blade 11 and nozzle 12, which are the inner structural members. Thus, a driving force for moving the screw device 15 towards the narrow pathway of the steam turbine is generated by the frictional force created by contacting between the helical notches 19 with the blade 11 and nozzle 12. Then, the screw device 15 advances towards the narrow pathway of the steam turbine.
Further, it is also possible to incorporate a video scope driver 27 and a screw device retainer 28 as shown in
In the foregoing description, the screw device driver 22 holds the screw device 15 between the drive wheel 23 and the auxiliary wheel 24, where the rotational force is applied to the screw device 15 by rotating the drive wheel 23 by the drive motor 26 so that the screw device 15 is sent through the steam turbine. However, it is also possible, as shown in
As shown in
In the condition where the retainer 32 is holding the screw device 15 and the rotational force from the drive motor 26 is applied to the drive shaft 30 through the disk 31, the rotational force is also applied to the screw device 15 that is being held by the retainer 32, thus, the screw device 15 itself begins to rotate. As a result, as explained above, the helical notches 19 on the main body 18 engage with the surfaces of the blade 11 and nozzle 12, which are the inner structural members of the steam turbine, the driving force for moving the screw device 15 towards the narrow pathway of the steam turbine is generated by the frictional force created by the engagement with the surfaces of the blade 11 and nozzle 12.
Here, if the inspector holding the portable type screw device driver 22 moves along the driving force (i.e., in the direction where the driving force becomes relaxed) with the screw device 15, the screw device 15 advances into the narrow part of the steam turbine. Accordingly, the inspector consecutively moves closer to the steam turbine along the advancement of the screw device 15. When the inspector holding the portable type screw device driver 22 reaches close enough to the blade 11, which is the entrance of the steam turbine, the inspector operates the retainer 32 to release the screw device 15, and only the inspector and the screw device driver 22 retreat therefrom. By repeating this procedure, the screw device 15 advances further and deeper into the steam turbine.
According to the second embodiment described above, since the screw device 15 can automatically advance forward by the screw device driver 22 instead of manually moved by the inspector, the inspection work for the internal structural member of the large-scale system is reduced. In addition, in the case where the video scope driver 27 is incorporated, the inspection work is further reduced, since the video scope can automatically move forward as well.
Next, the third embodiment of the present invention will be described in detail.
When a rotational force is applied to the rotating drum 29 by the drive motor 26 of the screw device driver 22, which rotates in a forward direction, the screw device 15 that is wound around the rotating drum 29 rotates and comes out from the rotating drum 29, thereby going inside of the steam turbine. As a consequence, as noted above, the helical notches 19 on the main body 18 contact the surfaces of blade 11 and nozzle 12. By the frictional force created by contacting the surfaces of the blade 11 and nozzle 12, a driving force is generated to move the screw device 15 in the direction of the narrow pathway of the steam turbine. Accordingly, the screw device 15 advances in the narrow pathway of the steam turbine. On the other hand, when the drive motor 26 is rotated in a reverse direction, the screw device 15 also rotates in the reverse direction, thereby being extracted from the steam turbine and wound around the rotating drum 29.
Moreover, a video scope driver 27 can be installed if necessary. The video scope driver 27 holds the video scope 14 and sends it through the screw device 15 by pressing the video scope 14 forward. The video scope driver 27 can be formed of a drive motor and a conversion device for converting the rotational force of the drive motor 26 into a linear motion. Thus, the video scope 14 can be automatically sent out by the video scope driver 27.
According to the third embodiment, since the screw device 15 can automatically be sent out by the screw device driver 22 instead of manually moved by the inspector, and the screw device 15 can be wound around the rotating drum 29, storing the screw device 15 is easy and an area at the outside of the steam turbine for the screw device 15 can be reduced.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
