Claims:1. A motorized scanner for longitudinal and latitudinal traversing between coiled tubes inside a steam generating water tube boiler, said motorized scanner comprising a scanning device including a thin frame configured to traverse an inspection tray containing at least one electromagnetic or ultrasonic sensor through the gaps between the coils for inspection of the coils for structural integrity or defects.

2. The motorized scanner as claimed in claim 1, wherein said motorized scanner is adapted to inspect the entire height of in-situ coils with motorized setup that allows automatic longitudinal or vertical traverse of said scanning device by means of a lead screw.

3. The motorized scanner as claimed in claim 1, wherein said motorized scanner is adapted to inspect the entire height of in-situ coils with mechanical setup that allows manual latitudinal or horizontal traverse of said scanning device by means of plurality of rollers.

4. The motorized scanner as claimed in claim 1, wherein said inspection tray comprises at least one sensor in a motorized articulated spring arrangement which is adapted to bring said at least one sensor in close proximity to the tubes in the coils for traversing along the length of the tubes to be inspected.

5. The motorized scanner as claimed in claim 1, wherein said scanning device comprises at least one camera.
, Description:FIELD OF THE INVENTION
The present invention relates to an inspection tool for coiled tubes in a steam generating water tube boiler, and more particularly, a special semi-robotic motorized scanner to inspect the coiled tubes through limited gap of 25 mm in in-situ condition.

BACKGROUND OF THE INVENTION
The inspection of coiled tubes or other conduits for service defects is necessary for operators of a steam generating water tube boiler wherein high pressure, high temperature water and steam are transferred.

The inspection of the installed tubing inside a steam generating water tube boiler is challenging. It is extremely difficult to access sections of the installed tubing which are within a confined inaccessible area of the boiler. There is a high possibility that significant structural degradation can occur after an extended period of operation under conditions of high pressure, high temperature, and/or corrosive environment.

Many techniques have been developed in the past to inspect manufactured tubing by removing the coiled tubes out from the series arrangement at the header joints by opening the boiler walls during the shutdown period for inspection. This process is time consuming and results in loss of revenue due to shut down time. Further, it is difficult to remove all the coils from boiler and inspect all of them considering the costs associated with it. Also, partial inspection could lead to an emergency shutdown due to tube failures.

Several prior art documents have attempted to overcome this challenge. United States Patent Appl. No. US 2009/0316531 teaches a scanner which performs scanning of tube with the help of an ultrasonic probe, a waveguide (wedge) secured relative to the probe, and an encoder secured relative to the probe. To overcome the challenge of removal of all tubes from boiler in order to inspection the disclosed scanner carries out inspection of tubes of boiler in in-situ condition by using ultrasonic technique.
Another United States Patent US 5549004 teaches the scanner which detects corrosion damage to tubes by performing ultrasonic scanning. The disclosed scanner comprises ultrasonic scanner probe equipped with plurality of dual element transducers having concave cylindrically curved surfaces for simultaneously examining arcuate areas of walls of several tubes as the probe is moved along the waterwall.

The scanning of tubes can also be done by using laser technique which is taught by Chinese Patent CN204405022U. The scanner claimed in CN204405022U comprises a straight line track, a slide bar, a three-dimensional laser scanner, a motor and a runner. This patent teaches three-dimensional modelling of tubes by using laser technique.

The present invention is designed to save time and cost by enhancing the inspection capabilities of in-situ coiled tubes, which otherwise would require dismantling the existing asset then inspecting and re-installing, which results in wastage of time, money and resources.

The present invention is related to the inspection of the structural integrity of installed coiled tubes which are in a confined space of a boiler, where multiple numbers of coiled tubes are in a series like arrangement connected to a header at both ends by using electromagnetic techniques or sound wave techniques and camera systems.

OBJECTS
It is an object of the present invention to provide a motorized scanner which can carry out scanning of each tube in the coil through longitudinal/vertical and latitudinal/horizontal axis.
Another object of the present invention is to provide a motorized scanner which can carry out scanning of exterior and interior of each tube in the coil.
Still another object of the present invention is to provide a motorized scanner which can carry out scanning of each tube in coil without removing the coil outside the boiler.
Yet another object of the present invention is to provide a motorized scanner which can carry out scanning of each tube in coil by using electromagnetic or ultrasonic sensors, multiple motors and multiple cameras.
One more object of the present invention is to provide a motorized scanner which can carry out 100% inspection of coiled tubes inside the pressure vessel itself and within the turnaround period of the vessel.

SUMMARY OF THE INVENTION
According to a preferred embodiment of the present invention, there is provided a motorized scanner for examining the interior and exterior of each tube in a coil for determining the material imperfections using electromagnetic techniques or sound wave techniques and camera systems.
According to a preferred embodiment of the present invention, the motorized scanner comprises a semi-robotic motorized setup to traverse the sensors to the gaps between two adjacent coils and to circumferentially hold the inspecting tube.
According to present invention the embodiment further comprises top and bottom support plate, guide tube, lead screw, rollers, adjuster, motor unit and scanner. The top and bottom support plate and guide tube together form a frame to support the electromagnetic or ultrasonic sensors.
According to a preferred embodiment, the scanner further comprises back plate and the front cover, inspection tray, cassette, articulation motors and cameras. The back plate and the front cover acts as a frame assembly to hold the inspection tray. The inspection tray includes cassette and articulation motors. The electromagnetic or ultrasonic sensors are fitted into cassette.
The preferred embodiment of the present invention performs longitudinal/vertical and latitudinal/horizontal scanning of installed coiled tubes without removing the coiled tube from the boiler.
According to the preferred embodiment, the top support plate and guide tube are responsible for longitudinal/vertical transverse while rollers located at top and bottom of inspection tool responsible for latitudinal/horizontal transverse.
According to the preferred embodiment of the present invention, the motorized scanner can perform longitudinal/vertical transverse within the range of 500 mm to 5000 mm.
The preferred embodiment of the present invention is made up of stainless steel. The present invention can inspect coiled tubes which are in inaccessible area inside the boiler.

BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will now be described with the help of accompanying drawings, in which,
Fig. 1 shows the flow-chart for a steam generating water tube boiler;
Fig.2 shows the detailed presentation of a type of steam generating water tube boiler;
Fig.3 shows the motorized scanner for longitudinal/vertical and latitudinal/horizontal traversing between each coiled tube;
Fig.4 is a detailed drawing of the motorized scanner illustrating its various components;
Fig.5 shows the motorized scanner positioned on the coiled tubes;
Fig.6 shows the motorized scanner in between coils inside a boiler; and
Fig.7 shows the motorized scanner on each tube of inspecting coil.

DETAILED DESCRIPTION
The preferred embodiment of the present invention is described herein below. The present invention is a motorized scanner which carries out inspection of each tube of coil fitted inside the boiler. The Fig.1 describes the flow chart 10 for a steam generating water tube boiler, where the coiled tubes are present in the economizer which pre-heats the feed water, the super heater which removes moisture from the steam converted from water, and the reheater which reheats the superheated steam after first stage of turbine rotation. The basic concept of a steam generating water tube boiler is that water is converted to steam in a closed vessel and as the volume of one-unit mass of steam is thousand times that of water, the pressure inside the vessel increases. Boiler uses this principle to produce high pressure steam which is passed to the turbines to generate electricity.
Fig.2 shows the detailed presentation of a type of steam generating water tube boiler 20. The present invention is primarily designed for the inspection of coiled tubing 22 in the boiler 20 as indicated in the Fig. 2. Preferably, the scanner is made of stainless-steel material.
Fig.3 shows the detailed structure of the motorized scanner, generally referenced by the numeral 100. The motorized scanner is configured for the inspection of each tube in a coil (referenced by numeral 311 in Fig. 5). The motorized scanner 100 comprises top and bottom support plates 101 and guide tube 102, which form the main frame for the probe and are made of stainless steel. The top support plate 101 and the guide tube 102 are fitted on a top plate 104 by means of lead screws 103 for traversing the scanning device 110 in the longitudinal/vertical direction from the top support plate to the bottom support plate 101. The motorized scanner 100 comprises a first pair of rollers 106 fitted at the operative top and a second pair of rollers 107 fitted at the operative bottom of the scanner 100. The top rollers 106 provided on the top support plate 101 are supported by a pair top support roller 105. The rollers 105, 106 & 107 provide resistance-free latitudinal/horizontal movement of the probe. The rollers are preferably made of nylon. The second pair of rollers 107 are bottom rollers which can be adjusted by means of bottom roller adjuster 108. The motorized scanner 100 further comprises a motor unit 109 provided at the operative bottom.

Fig. 4 illustrates the scanning device 110 in detail. In Fig. 3, the numerals 110-A and 110-B illustrate a side-view of the scanning device 110 on the tube in a coil. The scanning device 110 is made of stainless steel. The scanning device 110 comprises one or more electromagnetic and/or ultrasonic sensors. Further, the scanning device 110 comprises one or more motors and a plurality of cameras for 100% inspection of each tube in the coil over which the motorized scanner is passed. A back plate 201 and a front cover 202 define the main (thin) frame of the scanning device 110. The thin frame holds the inspection tray 203 which is fitted with one or more cassettes 204 and one or more articulation motors 205. The cassettes 204 contain the highly sensitive electromagnetic or ultrasonic sensors configured to detect every service defect induced in the tubes to be scanned. The cassettes 204 are fitted on to the inspection tray 203 by means of a spring-loaded arrangement and articulation motors 205 for adjusting the sensors on to the tubes to be inspected/scanned. The articulated spring arrangement is adapted to bring the sensors in close proximity to the tubes in the coils for traversing along the length of the tubes to be inspected. The scanning device 110 comprises a plurality of cameras such as top side view camera 206, bottom side view camera 207 and support camera 209. The scanning device 110 further comprises lights 208 for providing 100% visual examination of the tube areas to be scanned.

Figs. 5 & 6 illustrate the arrangement of the scanning device 310 of the motorized scanner A on the tube in a coil 311. The scanning device 310 of the motorized scanner A is adapted to perform longitudinal/vertical and latitudinal/horizontal scanning of each tube in a coil 311. The scanning is performed by using electromagnetic or ultrasonic waves. The electromagnetic or ultrasonic sensors produce signals, and accordingly the structural integrity of coiled tubes and defects like pitting, erosion, hydrogen damage and heat stress to the installed coiled tubes as a result of high pressure and high temperature steam generation in water tube boiler over a period is inspected. The motorized scanner can perform longitudinal/vertical transverse within the range of 500 mm to 5000 mm.

The scanning of each tube in the coil 311 is performed by moving the motorized scanner A through the longitudinal axis and the latitudinal axis. The movement of the motorized scanner A through the longitudinal axis is carried out with the help of support plates, guide tubes and lead screw (as described in Fig. 3 above). As illustrated in Fig. 7, the motorized scanner A moves longitudinally with the help of lead screw to hold the particular tube in a coil 311 for performing the scanning. The movement of the motorized scanner A through latitudinal axis is done manually by the inspection engineer with the help of rollers which are fitted on the operative top and operative bottom of the motorized scanner A.
The advantage of the motorized scanner A is that it can access coiled tubes 311 fitted in difficult area of the boiler. Fig. 6 describes the movement of the motorized scanner A through tubes which are apart from each other by 25 mm.
It will be appreciated by those skilled in the art that the probe, according to the preferred embodiment of the present invention, is able to conduct a complete examination of the entire tubes in coils 311 inside confined boilers by multiple longitudinal and latitudinal movements of the scanner.
The completeness and accuracy of the tube inspection provided by the motorized scanner according to the present invention can greatly reduce the time spent in inspecting and therefore servicing the boilers used for power generations. Reduced maintenance time translates into reduced time offline and increased plant productivity. It is to be understood that the figures and the description have been directed primarily toward the illustrative, preferred embodiment of the present invention, and the equivalent embodiments utilizing functionally and/or structurally equivalent components which are or become apparent to those skilled in the art are also within the scope of the proceeding disclosure and the following claims.