RADIATION VIEWER FOR INSPECTING AN ENCLOSURE

RECEPTEUR DE RAYONNEMENT POUR INSPECTER L'INTERIEUR D'UNE CHAMBRE

English Abstract

ABSTRACT OF THE DISCLOSURE
A device for inspecting the interior of an enclosure
comprises an instrument which receives radiation from the inter-
ior of the enclosure through an orifice at one end of the instru-
ment. A screen located immediately in front of the instrument
has an opening in register with the orifice. Compressed gas is
passed between the instrument and the screen and escapes through
the opening. The surface of the screen remote from the instrument
is cleaned periodically or continuously, e.g. by scraping, at
least around the opening.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for inspecting the interior of an enclosure,
comprising: (a) an instrument for receiving radiation from the
interior of the enclosure, the radiation being received through
an orifice at one end of the instrument; (b) a screen located
immediately in front of the instrument and spaced therefrom, the
screen having an opening in register with the said orifice, of
the instrument; (c) means for passing a compressed gas through
the space between the instrument and the screen and then through
the opening in the screen; and (d) means for cleaning at least
that part of the surface of the screen remote from the instrument
which part contains the said opening.
2. A device as claimed in claim 1, in which the screen
forms part of a closed case containing the instrument, means being
provided for turning the case in order to vary the direction
from which radiation is received by the instrument.
3. A device as claimed in claim 1, in which the trans-
verse dimensions the said orifice and the said opening are smaller
than 10 mm.
4. A device as claimed in claim 1, in which the
angular aperture of the said orifice for the reception of radia-
tion is at least 40°.
5. A device as claimed in claim 4, in which the said
angular aperture is at least 60°.
6. A device as claimed in claim 1, in which the said
cleaning means comprises a scraper.

Description

~66535
The present inyention relates to a device for
inspecting the interior o~ an enclosure, es~ecially (but not
solely) for inspecting material contained in the enclosure.
The following description illustrates an application
of the device to the inspection of the upper surface of the
burden in a blast furnace. This is done, however, by way of
example and without implying any limitation of the applicability
of the device. A de~ice according to the invention can be used
for observing the interior of any enclosure.
There is a well-recognized interest in observing what
goes on in a blast furnace at the upper surface of the charge
or burden, e.g. the evolution of the shape of this surface,
the distribution of surface temperatures from its centre to
its periphery, and the appearance of hot spots or cold zones. -
These indications allow the operation of the blast furnace to be
improved, this depending on appropriate addition of coke, or~ ,~
and fluxes as well as on accurate distribution of these materials
across the whole of the upper surface of the burden.
The value of all data is of course subordinate to the
fact of being able to correctly observe the burden by means of
a device which is as reliable as possible. This condition cannot
: . .
easily be met, because the space above the burden in the blast
furnace may contain a compressed gas (for example, at a pressure
of 2 kg) and is practically always very dusty.
~ .

~066535
In order to Qbserve the charge inside a blast furnace,
various devices ha~e already ~een su~gested which are generally
of the type in which scanning occurs inside a practically fixed
device, or of telemetric type. In most cases, these devices
permit observa~ion o~ the burden in a blast furnace through
an inspection window of transparent material permanently cleaned
from inside. The increase in back pressure inside blast furnaces
has made the use of such inspection windows more risky. The
inspection windows are difficult to clean satisfactorily by
scraping. Moreover, it is difficult to ensure a jet of gas on
the inner face of the inspection hole in order to clean it.
The present invention provides a device for inspecting
the interior of an enclosure, comprising: (a) an observation
or measuring instrument which terminates at its observation
end with a very small orifice (preferably smaller than 10 mm)
having a large angular aperture (preferably greater than 60);
(b) a screen located before and next to the instrument referred
at (a) and formed with a very small opening (preferably smaller
than 10 mm) facing the end opening of the instrument; (c) means
for circulating a compressed gas in the space between the
instrument and the screen and then through the opening formed
in the screen; (d) means for periodically or ~ontinuously clean-
ing the surface of the screen remote from the instrument, at
least at the part of the screen comprising the opening.

;S535
rrhe above device accordin~ to the invention is applic-
able, for example, in the observatlon of what is cJoing on in an
enclosure, or in measuring the surface temperature of m~terial
contained in the enclosure. It is sufficient to sealingly fix
the device to any aperture of suitable dimensions formed in
the wall of the enclosure. The enclosure could be a blast
furnace or any other kind of furnace. So far as the instrument
is concerned, it could be a simple sighting instrument, or a
television camera sensitive to visible radiation or infra-red
radiation, or any other radiation-receiving instrument (e.g. a ~; ;
- telemeter or a pyrometer) either scanning or not.
The device may further comprise means arranged to rotate
the device about a point located close to the outlet orifice of
the instrument. This variant allows the sighting axis of the
instrument to be oriented at will in any directions, the whole
device being, in this case, located in a sealed case. In
particular, the screen may form part of a closed case containing
the instrument, means being provided for turning the case in
order to vary the direction from which radiation is rec~ived
by the instrument.
The invention will be described further, by way of
example only, with reference to the accompanying drawing, whose
sole figure shows a longitudinal cross-section through the end
Of an obsexvation device for inspecting the upper surface of
; the burden in a blast furnace~
In the drawing, the end of an objective is referenced
1 and is cylindrical in shape. Also visible are the side
~30
'
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... . . .

~6653C;
wall 2 of the blast fu~nace and the interior 3 of the
furnace, The ob~ective 1 is surrounded by two coaxial cylindri-
cal ~ackets 4 and S whose ends are welded at 6 and 7 to a ring
plate 8. The end o~ the objective 1 has an orifice or pupil 9
(less than 10 mm in diameter) in register with a small opening
10 in a screen 11 fixed (by screwing) to the plate 8. The
pupil 9 permits sighting within an angle of at least 40 (prefer-
ably at least 60), which is also permitted by openinq 10 (less
than 10 mm in diameter).
The assembly is sealingly fixed to the side wall 2
by means of a conventional system including clamps 18 and bolts
9, around an aperture or bore 20 ~ormed in the side wall 2.
A compressed-air supply (not shown) ensures that dry,
oil-free air flows between the objective 1 and the jacket 4 in
the direction of the arrow 12 and then flows in the direction
of the arrow 13 in the restricted space between the objective 1
and the screen 11, before escaping through the open.ing 10,
thereby sweeping out the opening 10 towards the interior of
the furnace.
The inner faces of the ring 8 and the screen 11 are
located in the same plane 14. A scraper 15, which is reciprocated
by a rod 16 along the axis 17 of the rod, ensures cleaning of
the surface of the screen 11 remote from the objective 1 about
the opening 10. Thus the opening 10 and the area around it are
regularly cleaned of undesirable material which tends to collect
there.
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. . .