FIELD OF INVENTION
The present invention relates to an inspection device (D) and a method
for checking compartmental openings of Windbox of Supercritical boilers in
thermal Power Plants.
BACKGROUND OF THE INVENTION
Fossil boilers are widely used for generation of power in thermal power
plants. The boiler is the chief element in thermal power stations where the
conventional fossil fuel is burnt and the heat of combustion is used to convert
water into steam which then turns the turbine leading to generation of
electricity. There is a component called as wind-box through which the fuel that
is required to be brunt is fed into the boiler. The windbox is a box type of welded
structure consisting of many compartmental openings for housing nozzles for the
passage of fuel and air. These compartmental openings are very critical for the
further assembly with other components. If required dimensions are not
maintained within tolerance limits, then it may lead to lot of fit-up issues at site.
The compartmental openings are formed by welding many transverse members
across the length of the windbox. The dimensions are likely to vary due to
welding. Therefore, after welding, dimensions of the compartmental openings
have to be checked.
The conventional method of dimensional checking is by using a measuring
tape.' This method consumes lot of time and measurement errors are likely to
happen. Repeated measurements are required to be taken at various stages of
welding. Therefore, to make this measurement job easier and to speed up the
measurement process, a new inspection device is proposed in this invention.
The details regarding the design, fabrication, way of using this device has
been disclosed in the invention.

PRIOR ART SEARCH
US Patent US 20130142297 Al presents an inspection method by robotic
means, the interior of a nuclear steam generator for checking corrosion of tubes.
But our invention deals with a method of checking the compartmental openings
in a windbox of once-through supercritical boilers.
US Patent US 20130129189 Al describes an optical imaging inspection
process for the position accuracy of features of semiconductor devices wherein
the captured image of an area of a semiconductor is compared with the master
reference image and the defects are identified. But, our invention relates to the
method of using a specially designed inspection device for quickly checking the
correctness of dimensions of all compartmental openings in windbox of once-
through supercritical boilers with the primary aim of serving as go/no-go gauge
for dimensional inspection.
US Patent US 20130243145 Al refers to a device for inspecting welds in
nozzles of a containment vessel filled with water in a nuclear power plant
wherein said device is connected to a control processing unit located outside said
water. Our invention is different in the sense that it is concerned with the
method of checking the compartmental openings in Once-through supercritical
boiler windbox.
US 6220498 Bl describes about a portable unit for on-site welding of
sections of coiled tubing comprising a container for carrying out welding
operations therein, a tube clamping rig located inside said container and adapted
to clamp two sections of tubing in abutting end to end relationship . But, in our
invention, a method of quickly checking the compartmental opening of windbox
of once-through supercritical boiler is detailed.

OBJECTS OF THE INVENTION
Therefore, it is an object of the invention to propose an inspection device
(D) and a method for checking compartmental openings of Windbox of
Supercritical boilers in thermal Power Plant which is capable of providing a quick
inspection method to check the dimensions of the compartmental openings in
once through Supercritical boiler Windbox in Thermal power plants.
Another object of the invention is to propose an inspection device (D) and
a method for checking compartmental openings of Windbox of Supercritical
boilers in thermal Power Plants which is capable of providing a quick inspection
device for checking the compartmental opening that is easy to use without error
and consumes less time.
SUMMARY OF THE INVENTION
According to the invention, a method of developing a special device for
quickly checking the compartmental openings of a once-through supercritical
boiler windbox is disclosed.
The windbox is made of structural grade of carbon steel and involves
laying multiple welds at various locations all through the length of the
component and therefore is prone to welding induced distortion. The dimensions
of the compartmental openings of the windbox are likely to be influenced by the
welding method employed. Hence, the method of developing and using new
inspection device for checking the compartmental spacing is explained in this
invention.
The invention relates to the method of using a new device for- the
inspection of the compartmental openings of windbox of once-through

supercritical windbox. A lengthy rod of a desired length is taken. The length of
the rod may be taken equal to the length of the windbox. Thereafter, multiple
plates of width slightly lesser than the width of the compartmental openings of
the windbox are taken. These plates are attached to the length rod taken
initially. The attachment may preferably done by welding. The position of plates
on the rod is decided based on the position of the compartments over the entire
length of the windbox.
This device will serve as go-gauge for inspecting the compartmental
openings of the windbox of once-through supercritical boilers. The device so
developed has to be simply inserted into the various compartments at the same
time by holding it against the windbox. If there is no distortion in, the
compartments due to welding, the plates that are attached at different locations
on the device will easily enter the compartmental spacing. In case of distortion of
the compartmental openings, the plates attached to the device will not easily
enter into the compartments. This could serve as a quick inspection device for
checking the dimensional accuracy of windbox compartmental openings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 : Shows the inspection device for checking the compartmental
openings of windbox of once-through Supercritical boiler.
Fig. 2 : Shows the method of using the inspection device.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
According to the invention, there is disclosed a method of developing and
using a special inspection device for quickly checking the dimensional accuracy of
the various compartmental openings of windbox of once through supercritical
boiler, in order to minimize the inspection time.
The windbox is made of structural grade of carbon steel. It is a box type
of welded structure that contains a plurality of web plates positioned all through
the length and multiple longitudinally welded members. The web plates form
multiple compartments all along the length of the component.
After welding, there is a possibility of change of dimensions in the various
compartmental openings of the compartments due to welding induced distortion.
Therefore, the dimensional inspection has to be carried out for the
compartmental openings at various stages during the fabrication of windbox in
order to meet quality requirements. There is provided a method in this invention
to develop a special purpose inspection device for checking the dimensional
accuracy of the compartmental openings of windbox of once-through
supercritical boiler.
The special purpose inspection device is explained with reference to the
figure 1.
A rod (1) having a length covering the entire length of the windbox is
taken. The rod is made of mild steel but can be made of any other rigid material.
Multiple plates (2) of the required width are taken and are suitably attached to
the lengthy rod (1). The pre-determined width of the individual plates (2) shall
have to be decided based on the width of the compartmental opening (3)
present in the windbox. Plates are also made of mild steel but can be made of

any other rigid material. The width of the plate (2) that is to be attached shall be
lesser than the width of the compartmental opening (3) of windbox by an extent
of lmrh. The primary purpose of these plates (2) attached all along the length of
the rod (1) is to check the dimensional accuracy of the various compartmental
openings (3) of the windbox. Each plate (2) attached to the rod (1) shall be
corresponding to one compartmental opening (3) of the windbox. In all, the total
number of plates (2) attached to the rod (1) shall be equal to the total number
of compartmental openings (3) available in the windbox. The method of
attaching these multiple plates (2) with the rod (1) is done by means of welding.
It can be attached by any other means also. Each and every plate (2) attached
to the rod (1) shall have to be carefully prepared in order to just enter freely into
the corresponding compartmental openings (3) of the windbox. The position of
the plates (2) on the rod (1) is also very critical for the success of the functioning
of the device. The gap between one plate and the adjacent plate is decided
based on the spacing between the corresponding compartments in the windbox.
While attaching the plates (2) on the rod (1), care is to be taken that the center
of the plate thus fixed on the rod and the center of the corresponding
compartmental opening of the windbox coincides.
Figure 2 represent a schematic depiction of the method of using the
inspection device for carrying out the dimensional inspection of the
compartmental openings of the windbox. The inspection device is lifted to the
required elevation as decided by the height of the windbox by using two or more
persons. The said inspection device thus lifted is then slowly positioned so'that
the various plates (2) are just matching the corresponding compartmental
openings (3) in the windbox. Thereafter, the device is simply inserted into the
windbox in such a manner that each of the multiple plates (2) shall just enter
into the corresponding compartmental openings (3) of the windbox. If the

dimensions of the compartmental openings (3) are maintained as per original
planned ones, then the plates (2) present on the lengthy rod (1) will easily pass
through the compartmental openings (3). On the other hand, if the dimensions
of the compartmental openings (3) have varied due to welding induced distortion
or due to error in fit-up, then the plates (2) present in the inspection device will
not enter into the windbox. From this, it can be inferred that the compartmental
dimensions are meeting to the required levels. Therefore, the said inspection
device can aid the person carrying out the inspection of the windbox in deciding
the whether the dimensions of the compartmental openings (3) are meeting to
the required levels.
The proposed invention as narrated herein above should not be read and
construed in a restrictive manner, as some modifications, adaptations and
alterations are possible within the scope and limit of the invention as defined in
the encompassed appended claims.

We Claim:
1. An inspection device (D) and a method for checking compartmental
openings of Windbox of Supercritical boilers in thermal Power Plants comprising;
a rod (1) having a length covering the entire length of the windbox;
characterized in that,
a plurality of plates (2) welded to the rod (1) having predetermined width
based on width of compartmental opening (3) when the said width is less than
the width of the compartment opening (3) of the windbox by 1mm wherein the
gap between one plate to the adjacent plant is maintained equal to the spacing
between corresponding compartments in the windbox when center of the plates
(2) fixed on the rod (1) coincides with the center of the corresponding
compartmental opening (3) of the windbox.
2. A device as claimed in claim 1, wherein the rod (1) and the plates (2) are
made of mild steel material.
3. A method for inspection of checking compartmental openings of windbox
of supercritical boilers with the device claimed in claim 1, the said method
comprising;
lifting the inspection device (D) to the required elevation decided by the
height of the windbox;
positioning the said inspection device (D) to match the various plates (2)
with the corresponding compartmental openings (3) in the windbox wherein,

the device (D) is inserted into the windbox so that each of the multiple
plates (2) enters into the corresponding compartmental openings (3) of the
windbox to ascertain that the said openings are of required length and are not of
required dimension when the plates (2) of the inspection device (D) do not pass
through the compartmental openings (3).

ABSTRACT

This invention describes a method of developing and using a special
inspection device for checking the dimensional accuracy of compartmental
openings of windbox of once-through supercritical boilers. The windbox is a box
type of welded structure consisting of a base plate welded with a plurality of web
plates to form multiple compartments. These compartments are the provisions
for the fuel and air to enter the boiler. All the compartmental openings of the
windbox are to be critically maintained. There is a likelihood of change of
dimensions of the compartments during fabrication because of welding induced
distortion. The compartmental openings have to be checked during various
stages of manufacture. Therefore, there is proposed in this invention, a method
of developing a special device and an inspection technique for checking the
compartmental dimensions of the windbox. The inspection device consists of a
plurality of plates of width slightly lesser than width of the corresponding
compartment of the windbox. These plates are then attached to a lengthy rod.
This inspection device has to be lifted and inserted into the windbox after
properly matching all the compartmental openings. If the compartmental
openings are of the required length, then the plates attached to the rod shall
easily pass through. In case of change of dimensions due to distortion, the plates
attached to the rod in the inspection device will not pass through the
compartmental openings thereby serving as quick inspection method.