Furnace observation apparatus

A furnace observation apparatus for observing the state in a high temperature atmosphere furnace, which comprises an optical member to be inserted and disposed in a through-hole formed in a furnace wall of the furnace, made of a material having a softening point higher than the furnace temperature and being capable of transmitting an image observed in the furnace, and a photographing means to be disposed outside of the furnace, for photographing the image observed in the furnace, transmitted from the optical member.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a furnace observation apparatus for
 observing the state of a high temperature atmosphere furnace such as a
 glass melting furnace or an incinerator.
 2. Discussion of the Background
 JP-A-9-307795 discloses a furnace observation apparatus comprising a
 cylindrical member to be inserted in a furnace and a CCD camera attached
 to the forward end of the cylindrical member, wherein the cylindrical
 member has a multi-cylinder structure comprising a plurality of cylinders,
 and it is constructed to photograph the state in the high temperature
 atmosphere furnace while cooling the CCD camera by supplying a cooling
 liquid or a cooling gas to a space between such cylinders.
 However, such a conventional furnace observation apparatus has had a
 drawback that the structure of the apparatus tends to be complex, since
 the cylindrical member is constructed to have a multi cylinder structure
 to let the cylindrical member have a cooling function.
 Further, such a furnace observation apparatus has a structure in which the
 cooling air used for cooling the CCD camera will leak into the furnace,
 whereby NO.sub.x is likely to be formed in the furnace by the leaked air.
 Further, it has a drawback that the furnace is cooled by the leaked air.
 Especially, in the case of a glass melting furnace, if NO.sub.x is formed
 in the furnace or if the temperature in the furnace changes, such will
 cause deterioration of the quality of glass, or such is undesirable from
 the viewpoint of the environmental safety.
 SUMMARY OF THE INVENTION
 The present invention has been made under these circumstances, and it is an
 object of the present invention to provide a furnace observation
 apparatus, whereby the state in a high temperature furnace can be observed
 with a simple structure without necessity to provide a cooling function to
 cool the optical member.
 To accomplish the above object, the present invention provides a furnace
 observation apparatus for observing the state in a high temperature
 atmosphere furnace, which comprises an optical member to be inserted and
 disposed in a through-hole formed in a furnace wall of the furnace, made
 of a material having a softening point higher than the furnace temperature
 and being capable of transmitting an image observed in the furnace, and a
 photographing means to be disposed outside of the furnace, for
 photographing the image observed in the furnace, transmitted from the
 optical member.
 According to the present invention, an optical member made of a material
 having a softening point higher than the furnace temperature and being
 capable of transmitting an image observed in the furnace, is disposed in a
 through-hole formed in a furnace wall, and the image observed in the
 furnace which is transmitted by this optical member, is photographed by a
 photographing means installed outside of the furnace. Thus, the state in
 the high temperature furnace can be observed with such a simple structure
 without necessity to provide a cooling function to cool the optical
 member.
 Further, according to the present invention, the optical member of the
 above furnace observation apparatus is preferably made of quartz glass. If
 the optical member is made of quartz glass, it will have high heat
 resistance and can be used without problem even in a furnace with a high
 temperature atmosphere.
 Further, according to the present invention, the furnace observation
 apparatus is preferably provided with a cooling means for cooling the
 photographing means. Thus, it is possible to prevent by the cooling means
 a failure of the photographing means due to the heat of the furnace.

DESCRIPTION OF THE EMBODIMENT
 FIG. 1 is a cross-sectional view of a principal portion illustrating a
 state in which a furnace observation apparatus 10 according to one
 embodiment of the present invention is installed on a glass melting
 furnace 12. The furnace observation apparatus 10 shown in the Figure is an
 observation apparatus for observing the state of the surface of the molten
 glass C melted by a glass melting furnace 12, and as shown in FIG. 2, it
 comprises an optical member 14 as a light guide formed in a rod shape, a
 condensing lens 16, a beam attenuating filter 18, a CCD camera 20, a
 monitor 22 and an air cooling device 24.
 The optical member 14 is made of a material having a softening point higher
 than the furnace temperature, such as quartz glass, and the forward end
 surface thereof constitutes an objective lens section 14A formed in a
 concave shape as shown in FIGS. 2 and 3, and the rear end surface thereof
 constitutes an eye lens section 145. Further, the circumferential surface
 14C of the optical member 14 is delustered, whereby the light of the
 observed image taken in from the above object lens section 14A will be
 totally reflected by the circumferential surface of the optical member and
 transmitted to the eye lens section 145 with little leakage from the
 optical member 14.
 As shown in FIG. 2, the optical member 14 is inserted in a cylindrical
 casing 26, so that the circumference in the axial direction of the
 rod-shaped optical member is not directly exposed to the atmosphere in the
 furnace. The casing 26 for the optical member is made of a material having
 heat resistance such as silicon carbide or alumina (i.e. a refractory
 material). The optical member 14 is inserted and disposed in a
 through-hole 30 formed in a furnace wall 28, as inserted in the above
 casing 26. Further, the position of the above casing 26 to be inserted in
 the through-hole 30 will be set so that the object lens section 14A of the
 optical member 14 will be located at a position suitable for observation
 of the surface of the molten glass G and the eye lens section 14B is
 located at a position outside of the furnace. After the position for
 insertion is so set, the casing 26 will be fixed in the through-hole 30
 via a heat resistance sealing material 32 such as a castable brick, a
 brick or a ceramic wool. By the sealing material 32, the interior and the
 exterior of the furnace is partitioned to prevent lowering of the
 temperature in the furnace. Further, by means of a sealing agent 33 such
 as ceramic wool, the optical member 14 is fixed to the casing 26.
 At the rear side (upper right-hand side in FIG. 2) of the eye lens section
 14B of the optical member 14, a photographing apparatus (which corresponds
 to the photographing means) comprising a condensing lens 16, a beam
 attenuating filter 18 and a CCD camera 20, is disposed. This photographing
 apparatus is disposed in a box type casing 34 for the photographing
 apparatus.
 The operation of the photographing apparatus is as follows. Firstly, the
 light of a observed image transmitted to the eye lens portion 14B of the
 optical member 14 will be condensed by the condensing lens 16, and the
 condensed light will be attenuated by the beam attenuating filter 18 to a
 predetermined brightness. This attenuated light of the observed image will
 form an image on a CCD light receiving screen of the CCI) camera, whereby
 the surface of molten glass G will be photographed with a predetermined
 brightness by the CCD camera 20. This photographed image of the glass
 surface will be displayed on a monitor 22. The monitor 22 is installed in
 an operation room (not shown) for remote control of the glass melting
 furnace 12 and will be watched by an operator. The condensing lens 16 and
 the CCD camera 20 are mounted and secured on the respective supports 36
 and 38. These supports 36 and 38 are provided on a table 40 installed in
 the casing 34 so that they are movable back and forth in the direction of
 the light axis A of the optical member 14. Thus, the positions of the
 condensing lens 16 and the CCD camera 20 will be set by moving the above
 mentioned supports 36 and 38 back and forth in the direction of the light
 axis A. The beam attenuating filter 18 may be attached on the condensing
 lens 16 side or on the CCD camera 20 side. Further, on the above table 40,
 a support member 42 is installed which supports the eye lens section 14B
 of the optical member 14.
 To the above casing 34, an air cooling apparatus 24 is connected via a pipe
 44. The air cooling apparatus 24 comprises a blower for sucking open air,
 and when this blower is operated, open air sucked by the blower will be
 supplied via a pipe 44 into the casing 34. The pipe 44 is attached at a
 lower portion of the casing 34, and an exhaust gas pipe 46 is attached at
 an upper portion of the casing 34. Accordingly, the open air supplied into
 the casing 34 will be an ascending stream, will pass through the
 photographing apparatus and will be discharged to the exterior from the
 exhaust gas pipe 46. By the stream of this open air, the photographing
 apparatus which is not heat resistant, will be efficiently cooled.
 Now, the operation of the furnace observation apparatus 10 having the above
 described construction, will be described.
 As shown in FIG. 1, if the casing 26 of the furnace observation apparatus
 10 is inserted and disposed in the through-hole 30 of the furnace wall 28,
 the observed image of the surface of molten glass G will be transmitted
 from the objective lens section 14A of the optical member 14 of FIG. 2 to
 the eye lens section 14B. Then, the transmitted observed image will be
 photographed by the CCD camera 20 of the photographing apparatus disposed
 outside of the furnace and will be displayed on the monitor 22.
 In this embodiment, the optical member 14 is made of quartz glass having a
 softening point higher than the furnace temperature and being optically
 homogeneous, specifically quartz glass such as molten quartz glass or
 synthetic quartz glass having a softening point of at least 1,500.degree.
 C., particularly preferably at least 1,650.degree. C., whereby it will be
 unnecessary to provide a cooling apparatus for cooling the optical member
 14. Thus, by the furnace observation apparatus 10 of this embodiment,
 simply by disposing the optical member 14 in the throughhole of the
 furnace wall 28, the surface of molten glass G can be photographed,
 whereby the structure will be simplified as compared with a conventional
 furnace observation apparatus.
 Further, in this embodiment, the interior of the casing for the
 photographing apparatus such as the CCD camera 20 having no heat
 resistance, is cooled by an air cooling apparatus 24, whereby a failure of
 the photographing apparatus due to the radiation heat of the furnace can
 be prevented.
 In this embodiment, the optical member 14 is made of quartz glass, but it
 is not limited thereto and may be made of any material which has a
 softening point higher than the furnace temperature and which is useful as
 an optical system.
 In this embodiment, the furnace observation apparatus 10 is applied to a
 glass melting furnace 12. However, the application is not limited thereto,
 and the furnace observation apparatus 10 of this embodiment can be applied
 also to other various furnaces such as incinerators.
 As described in the foregoing, according to the present invention, the
 furnace observation apparatus is constructed so that the optical member
 made of a material having a softening point higher than the furnace
 temperature and capable of transmitting an image observed in the furnace,
 is disposed through a through-hole of a furnace wall, so that the image
 observed in the furnace which is transmitted from the object lens section
 to the eye lens section of the optical member, is photographed by a
 photographing means disposed outside of the furnace, whereby the state in
 the furnace with a high temperature atmosphere can be observed with a
 simple structure without necessity to provide a cooling function to cool
 the optical member itself.
 Further, according to the present invention, the optical member is
 preferably made of quartz glass having a high softening point, and it has
 high heat resistance and can sufficiently be used even in a furnace with a
 high temperature atmosphere.
 Furthermore, according to the present invention, the photographing means
 having no heat resistance is preferably cooled by a cooling means, whereby
 it is possible to prevent a failure of the photographing means due to the
 heat of the furnace.