FIELD OF THE INVENTION
The present invention relates to a compact and portable camera system for real-
time monitoring of internal operating conditions of a blast-furnace. More
particularly, the invention relates to a compact and portable camera system to
view in real time the burden profile, gas profile and hot spot generation inside a
blast furnace.
BACKGROUND OF THE INVENTION
A conventional Furnace top camera unit is a robust system employing a set of
large stainless steel pneumatic cylinders, a plurality of large diameter ball valve,
multiple stainless steel cartridges, several Stainless steel cassettes. For
installation of the unit, a big hole is to be made in the shell of the furnace. The
unit being heavy, a large manpower is deployed to install, and commission
including heavy tools and tackles such as chain pulleys or cranes. The unit
provides a 75 Degree field of view generated by a set of large convex lenses.
The unit (cylinder part, which houses the lens system) comes out of the furnace
when the Nitrogen supply stops, and goes in when the supply resumes, thus
providing a safety for the lenses. The camera unit generates images only when
the inside temperature of the furnace rises above a certain threshold, rest of the
time the images are not displayed on the screen. The images are displayed in
the control room of the plant.

OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a compact and portable
camera system to view in real time the burden profile, gas profile and hot spot
generation inside a blast furnace.
Another object of the invention is to propose a compact and portable camera
system to view in real time the burden profile, gas profile and hot spot
generation inside a blast furnace, which minimizes punchuring of the blast
furnace shell during mounting or de-mounting of the system.
A still another object of the invention is to propose a compact and portable
camera system to view in real time the burden profile, gas profile and hot spot
generation inside a blast furnace, which allows consistent visual inspection of the
entire internal periphery of the blast furnace irrespective of inside furnace
temperature.
A further object of the invention is to propose a compact and portable camera
system to view in real time the burden profile, gas profile and hot spot
generation inside a blast furnace, which is maintenance-friendly.
SUMMARY OF THE INVENTION
Accordingly, there is provided a compact and portable camera system to view in
real time the burden profile, gas profile and hot spot generation inside a blast
furnace.

As per the inventive configuration, an inside circular area of the camera system
is calculated based on the dimension of the furnace shell. As opposed to prior art
which provides a minimum field of view of the camera system placed above the
shell, the inventive system can be installed at a higher altitude above the inlet of
the furnace where all gasses are sucked up to provide a better image. Based on
the required field of view the front ball lens are designed, which provides 95
Degrees of field view.
The image created by this ball lens is caused to fall on a fiber optic image
conduit. The face of the fiber image conduit is kept at the focal length of the ball
lens to recreate a sharper image on its face. The image conduit is held in the
center position by a fiber holder, which is specifically designed to give spacing to
the expandable glass rod due to high temperature expansion. The arrangement
for holding the ball lens provides resistance to the force of Nitrogen supply so
that the lens should not come out by high pressure Nitrogen used for cooling as
well as purging.
The image is recreated at the other face of the image conduit. A triplet lens is
utilized to focus the image on the conduit face to a CCD screen. The final image
thus converted into digital form to be displayed on the main screen in the
operator room. Utilization of the image conduit eliminates the heavy and costly
components, minimizes the size, replaces the use of zoom lens. Thus, the prior
art requirement of maintaining a minimum object distance of the zoom lens is
avoided. By integrating all these features a new cheap, light weight, easily
maintainable camera system has been invented.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 General arrangement of a blast Furnace.
Figure 2 Detailed view of the front unit of the camera system of the invention.
Figure 3 Fiber holder of the camera system according to the invention.
Figure 4 Ball mount assembly of the camera system
Figure 5 Intermediate tube part, and conduit holder of the camera system.
Figure 6 Triplet lens of the camera system.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 shows the general arrangement of the camera system where each and
every constituent component as arranged has been shown. The flanges as
shown are utilized to erect the system in the furnace shell. The couplings are
provided with screw arrangement for centering of all the optical components.
Nitrogen inlet employs a non-return valve to prevent back flow of the hazardous
gas to the Nitrogen circuit in case the nitrogen supply is stopped. Further, a
better housing back pressure inside the system is created. The camera holder
houses a CCD camera unit with proper connectors for electrical connection.

Figure 2 depicts the detailed design of the front portion of the system which
would be exposed to the hazardous environment of the Blast furnace interior.
This shows a plurality of ball lens with the field of view, a small aperture which is
the actual opening to the furnace, a fiber holder and a ball lens mounting
assembly.
Figure 3 depicts the fiber holder with slotted design to give a flexibility of the
expanded diameter of the fiber due to thermal expansion. This prevents crack
generation on the fiber due to the thermal expansion of the glass rod.
Figure 4 depicts the ball mount assembly to hold the ball lenses in place during
operation. Several clips are provided at 120 Degrees apart and a passage for
supply of Nitrogen to the aperture. The clips are designed such that the lens
would not come out against the high pressure of Nitrogen.
Figure 5 depicts an intermediate tube part which serves the dual purpose of
holding an image conduit at the center as well as for supporting the ball lens
assembly in place. It is also with perforated design to allow the passage of
Nitrogen through it.
Figure 6 shows a triplet lens used to focus the image created on the fiber image
conduit face into the CCD camera screen.

WE CLAIM :
1. A compact and portable camera system to view in real time the burden
profile, gas profile and hot spot generation inside a blast furnace, the
system comprising :-
a plurality of flanges to install an image capture unit of the system,
the unit being exposed to the hazardous operating conditions of
the boiler; and
a triplet lens disposed at an opposite end of the image capture unit
to focus the captured images to a close-circuit display device (CCD)
2. The system as claimed in claim 1, wherein the image capture unit
comprises a ball mount assembly holding a plurality of ball lenses, an
aperture configured on the furnace shell along the direction of the
lenses, a fibre image conduit located at the focal length of the ball lenses
such that the images captured by the lenses reflected on the conduit to
recreate sharper images; a fiber holder holding the image conduit in a
center position and to allow thermal expansion of the conduit due to high
temperature inside the furnace
3. The system as claimed in claim 1, comprising a non-return valve disposed
at the nitrogen inlet of the furnace to prevent back flow of hazardous gas
from the furnace.

4. The system as claimed in claim 1, wherein the triplet lens allows focusing
of the recreated sharper images by the fibre image conduit, and wherein
the CCD displays the converted digital image data.
5. The system as claimed in claim 2, wherein the ball lenses are mounted on
the ball mount assembly by a plurality of clips.

ABSTRACT

The invention relates to compact and portable camera system to view in real
time the burden profile, gas profile and hot spot generation inside a blast
furnace, the system comprising a plurality of flanges to install an image capture
unit of the system, the unit being exposed to the hazardous operating conditions
of the boiler; and a triplet lens disposed at an opposite end of the image
capture unit to focus the captured images to a close-circuit display device
(CCD).