EP3830041A1

EP3830041A1 - Glass furnace provided with optical fibers

Info

Publication number: EP3830041A1
Application number: EP19744720.4A
Authority: EP
Inventors: Mickaël BOINET; Isabelle Cabodi; Olivier Citti; Vincent Gleize; Jean-Gaël VUILLERMET
Original assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Current assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Priority date: 2018-08-01
Filing date: 2019-07-26
Publication date: 2021-06-09
Also published as: US20210310738A1; WO2020025492A1; FR3084661B1; RU2770207C1; BR112021001762A2; FR3084661A1; JP7282870B2; CN112789246A; MX2021001189A; JP2021533343A

Abstract

Glass furnace comprising: - a refractory portion defining a hot surface (16_c) that is in contact or is to come into contact with melted glass or with a gas environment in contact with melted glass, and a cold surface (16_f) at a distance from the hot surface; and - a temperature measuring device comprising: - a waveguide (12) comprising a measurement portion (20) having at least one temperature sensor (22) configured to transmit a response signal in response to the injection of an interrogation signal into the waveguide; and - an interrogator (14) which is connected to an input of the waveguide and is configured to inject the interrogation signal into said input, receive the response signal (Ri) transmitted by the sensor in response to the injection of the interrogation signal, analyze the received response signal and emit a message according to said analysis; in said furnace, the measurement portion (20) is sandwiched between the cold surface and a thermally insulating layer (18) or extends through said thermally insulating layer (18).

Description

GLASS FURNACE PROVIDED WITH OPTICAL FIBERS

Technical area

The present invention relates to a glass furnace provided with at least one waveguide, preferably an optical fiber.

State of the art

By reading temperatures at different locations in a glass furnace, you can check their status, in particular to detect hot spots corresponding to thermal bridges. This reading is carried out conventionally by means of thermo coup les. However, the implementation of thermocouples is long and does not allow continuous monitoring of the entire structure, the number of measurements being limited.

Alternatively, the temperatures are measured by infrared thermography, but this is only possible in places visually accessible by an infrared camera, which notably excludes the isolated parts of the blocks and the bottom of the oven.

There is therefore a need for a solution facilitating the measurement of temperature measurements at numerous points of a structure and allowing continuous and precise monitoring of their developments.

An object of the invention is to respond, at least partially, to this need.

Summary of the invention

According to the invention, this object is achieved by means of a glass furnace comprising:

a refractory part defining a hot face in contact or intended to be in contact with molten glass or with a gaseous environment in contact with molten glass, and a cold face separated from said hot face, and

- a temperature measuring device comprising:

a waveguide comprising a measurement part comprising at least one temperature measurement sensor configured to send a response signal in response to the injection of an interrogation signal into the waveguide; and

- an interrogator connected to an input of the waveguide and configured to inject the interrogation signal into said input, receive said response signal returned by the sensor in response to the injection of said signal interrogation, analyze the response signal received and send a message based on said analysis.

In a preferred embodiment, the measurement part is in contact with said cold face and, preferably, extends against the cold face.

The measuring part can also be partially or completely incorporated within the refractory part.

As will be seen in more detail in the following description, a waveguide is a particularly effective and practical means. In particular, several sensors can be incorporated into the same waveguide and several waveguides can be connected to the same interrogator. It is thus possible to easily build a network of measurement points. This network can be kept in place so as to allow a continuous reading of measurements.

An oven according to the invention may also include one or more of the following optional characteristics:

the waveguide is an optical fiber, preferably glass or sapphire;

the sensor is a Bragg grating;

the waveguide has a diameter of less than 200 micrometers;

the refractory part is an assembly of refractory blocks, in particular a side wall or a bottom of a glass melting tank;

the measurement part of the waveguide comprises several said sensors, preferably more than five, more than eight, more than ten, preferably more than twenty sensors;

the sensors are arranged at regular intervals along the waveguide;

the interrogator is configured to determine, as a function of the analysis of the response signal, a level of wear of the refractory part and / or a temperature of the hot face and / or a change in the temperature of the hot face;

the waveguide does not penetrate inside the refractory part;

at least the measurement part of the waveguide extends sandwiched between said cold face and a thermally insulating layer, or within said thermally insulating layer;

the thermally insulating layer consists of at least two elementary insulating layers; at least the measuring part of the waveguide extends in sandwich between two successive elementary insulating layers of said insulating layer;

at least the measurement part of the waveguide extends within one of the elementary insulating layers of said insulating layer;

the cold face is opposite, and preferably substantially parallel, to the hot face; the waveguide has the general shape of a fiber, the measuring part of which is preferably substantially straight;

the measuring portion of the waveguide extends, at least partially, or even completely, parallel to the hot face and / or to the cold face;

the measurement part is sandwiched between said cold face and a thermally insulating layer;

the interrogator and / or the measuring part are housed in a housing provided on the cold face or on the insulating layer or on an elementary insulating layer, in particular in the form of a groove or "groove", or through the part refractory, the insulating layer or the elementary insulating layer, preferably in the form of a tubular hole, straight or not, through or blind;

the interrogator and / or the measuring part are fixed to the refractory part and / or, where appropriate, to the insulating layer, by at least one fixing point, said fixing point having a length, along the part measuring, preferably greater than 1 mm, greater than 3 mm and / or preferably less than 5 cm, preferably less than 3 cm, 2 cm, 1 cm, or 0.5 cm;

the oven comprises a sheet made up of a set of parts for measuring said waveguides extending along a curved or planar surface, preferably planar, preferably along a plane parallel to the hot face and / or to the face cold;

said measurement parts of the sheet extend parallel to each other and / or intersect;

the measuring parts of said ply do not intersect and extend, preferably parallel to each other, being spaced apart from each other by a distance greater than 1 cm, greater than 5 cm, greater than 10 cm, greater than 20 cm, and / or less than 100 cm, less than 80 cm, or less than 50 cm;

at least part of the crossings between measurement parts, sensors are arranged on each measurement part; preferably, at more than 50%, preferably more than 80%, preferably more than 90%, preferably 100% of the crossings between measurement parts, each measurement part has a sensor;

at said crossings, all the measurement parts are in contact with each other;

the number of measurement parts crossing at a crossing point is greater than 2, even greater than 3 or greater than 5;

the oven comprises at least first and second said layers which preferably extend parallel to one another;

the distance between the first and second layers is greater than 1 cm, greater than 3 cm, greater than 5 cm, and / or less than 10 cm;

said measuring portions of the first ply extend parallel to each other;

said measurement portions of the second ply extend parallel to each other, preferably in a direction different from the direction of the measurement portions of the first ply, the angle between said directions preferably being greater than 45 °, 60 °, 80 ° and / or less than 120 °, preferably less than 100 °; when the first and second plies are observed in a direction normal to at least one of said first and second plies, said measurement portions of the first ply cross said measurement portions of the second ply and, preferably, more than 50%, preferably more than 80%, preferably more than 90%, preferably 100% of the crossings, each measurement part has a sensor;

the web sensors are distributed in a pattern, preferably in a regular pattern, preferably to form a mesh of square or rectangular meshes; the sheet extends under the floor or between two elementary insulating layers of the floor; the oven comprises several said sensors, in contact or not, superimposed along a direction perpendicular to the hot face;

each end of the waveguide is connected to a respective interrogator

The invention also relates to a process for reading measurements relating to a refractory part of a glass furnace according to the invention, said process comprising the following steps:

at. manufacture of a glass furnace according to the invention; b. controlling the interrogator so that it injects an interrogation signal into the input of the waveguide and receives a response signal from the sensor;

vs. analysis of the response signal so as to determine information dependent on said response signal, and in particular relating to a temperature of the refractory portion in the region of the sensor.

Brief description of the figures

Other characteristics and advantages of the invention will become apparent on reading the detailed description which follows and on examining the appended drawing in which:

- Figure 1 schematically shows the side wall of a preferred embodiment of an oven according to the invention, shown in perspective;

- Figure 2 (2a-2e) and Figure 5 show cross sections (Figures 2a and

2b, Figure 5) and top views of details of the side wall of Figure 1, the insulating layer being shown;

- Figure 3 (3a-3d) illustrates different signals used in a device according to the invention;

- Figure 4 illustrates an arrangement of optical fibers on a side wall of an oven according to the invention.

In the various figures, identical references are used to designate identical or analogous members.

Definitions

By "refractory part" means an element of the furnace made of a refractory material. A refractory part can be a block, but also an assembly of blocks, for example a side wall of a tank, or a bottom, in particular formed by casting. A refractory part is conventionally made of a molten material or of a sintered material. Conventionally, an insulating layer covers the cold face of the refractory part to limit heat exchange.

Conventionally, the "thickness" of a refractory part of a glass furnace is its dimension measured in a direction perpendicular to its hot face. For example, for a side tank block in contact with molten glass, the thickness is measured in a substantially horizontal direction directed towards the molten glass bath. For a sole, the thickness is measured in a vertical direction.

The "hot side" is the side of a refractory part that is exposed to an oven space containing molten glass or intended to contain molten glass. The hot face may be in contact, or intended to be in contact with molten glass and / or with the gaseous environment which extends above the molten glass. The hot face is thus the face of the refractory part which is subjected or is intended to be subjected to the highest temperatures. All of the hot faces of the blocks of the side wall of the glass melting vessel can also, by extension, be qualified as "hot face". The upper surface of the sole can also be described as a “hot face”.

Unless otherwise indicated, the "depth" is measured perpendicular to the hot side, towards the inside of the refractory part.

The adjective "warm" is used for clarity. Before the oven is in service, the “hot” side is the side which is intended to be subjected to the highest temperatures after putting into service.

A “cold face” is a surface of the refractory part which is not exposed to a space of the furnace containing molten glass or intended to contain molten glass, that is to say which is isolated from this space by material of the refractory part. The cold side opposite the hot side is the side which is furthest from said space. Conventionally, the cold face opposite the hot face is the face which, in service, is subjected or which is intended to be subjected to the lowest temperatures. The cold side can be parallel to the hot side.

By "waveguide" means any means, different from the refractory part, to guide an electromagnetic wave, and in particular a wave in the frequencies of the visible.

A measurement part "extends" in a layer (insulating layer, elementary insulating layer, refractory part of the oven enclosure) or between two layers when it extends substantially completely in said layer or between said two layers.

To assess whether two measurement parts intersect, these measurement parts are preferably observed perpendicular to the hot face. "Behave", "present" or "understand" must be interpreted in a broad, non-limiting manner.

detailed description

In general, the enclosure of a glass furnace comprises a refractory part and an insulating layer 18 attached to the cold face of the refractory part and intended to limit the heat exchanges by conduction between the inside and the outside of the oven. .

The refractory part therefore constitutes the first layer of the enclosure, from inside the oven. It can constitute the wall of the tank or the bottom.

It is conventionally made up of an assembly of blocks. These blocks generally have the form of refractory tiles to constitute the sole. Any refractory block used in conventional glass furnaces, possibly in the form of slabs, can be used. In particular, each block can be made of a molten material.

The refractory part, and in particular a block, can be made of a material made up, for more than 90% of its mass, of one or more oxides chosen from the group consisting of Zr0 ₂ , AI2O3, S1O2, CA Ch, Y2O3 , and CeCh. This material preferably contains more than 90% of Zr0 ₂ , AI ₂ O ₃ and S1O ₂ . In one embodiment, this material is an AZS (that is to say a product, preferably molten, whose majority constituents by mass are AI ₂ O ₃ , Zr0 ₂ and S1O ₂ ) and has more than 15% of Zr0 ₂ , preferably between 26 and 95% of ZrCh. Its composition is typically, for a total of more than 90%, preferably more than 95%: 26 to 40% Zr0 ₂ ; 40 to 60% AI ₂ O ₃ ; 5 to 35% S1O ₂ . The glassy phase represents approximately 5 to 50%, preferably between 10 and 40%. Preferably, this vitreous phase is a silicate phase whose mass proportion of Na ₂ 0 is less than 20%, preferably less than 10% and / or whose mass proportion of AbCh is less than 30%.

All percentages are conventionally by mass based on the oxides. Preferably, the oxides represent more than 90%, preferably more than 95%, preferably more than 98% of the mass of the refractory block.

The refractory part is preferably made of a material resistant to temperatures above 500 ° C, or even 600 ° C, even l000 ° C, even l400 ° C.

In the embodiment of FIG. 1, the glass furnace according to the invention comprises a refractory furnace part in the form of an assembly of refractory blocks 10, a waveguide, in this case an optical fiber 12, and a first interrogator 14i. The assembly of refractory blocks can be a side wall of a glass furnace tank, but the invention is not limited to such a side wall. Figure 1 shows a side wall with four vertical planes.

The shape of the side wall is not limiting.

In the embodiment shown, it consists of refractory blocks of generally rectangular parallelepiped shape and defines a hot face 16 _c and a cold face 16 _f , opposite the hot face 16 _c .

The thermally insulating layer 18, not shown in FIG. 1, is arranged against the cold face of the refractory part, preferably of the side wall or of the sole. In particular, the insulating layer can surround the side wall of the glass melting tank of the oven or extend under the entire surface of the cold face of the hearth.

Preferably, the thickness of the insulating layer 18 is greater than 10 cm, preferably greater than 20 cm, preferably greater than 30 cm.

The insulating layer 18 can be in one piece, in particular when the refractory part is a sole. In particular, it can be constituted by a layer of concrete which extends under the slabs constituting the sole. Advantageously, it can thus have a sealing function.

Alternatively, the insulating layer can be an assembly of several insulating blocks or, preferably, of several elementary insulating layers, which, themselves, can be assemblies of blocks.

FIG. 5 represents for example an assembly of several elementary insulating layers 18i, 18 ₂ adjacent.

For the sake of clarity, a distinction is made in the present description between an "elementary insulating layer" and an "insulating layer". An "insulating layer" may consist of a single layer or of several "elementary insulating layers".

The insulating layer 18 may consist of a layer of a single material. Preferably, the insulating elementary layer 18 then has a thermal conductivity less than 1.3 W. m ¹ ! ¹ , or even less than 1.0 W.m'.K ¹ . In one embodiment, the insulating layer 18 consists of a silico-aluminous refractory material, in particular a clay product.

The insulating layer 18 can be made of several different materials. In particular, it can be constituted by a juxtaposition of several elementary insulating layers 18i, 18 ₂ made of different materials.

Preferably, the last elementary insulating layer, that is to say the outermost layer relative to the interior of the furnace, has a thermal conductivity of less than 1.3 W. m '.K ¹ , or even less than 1.0 Wm fK ¹ . All common insulating materials can be used. The elementary insulating layer (s) located in the immediate vicinity of the cold face may consist of a material made up, for more than 90% of its mass, of one or more oxides chosen from the group consisting of Zr0 ₂ , AI2O3, S1O2, Cr ₂ 03, Y2O3, and CeCh. This material preferably contains more than 90% of Zr0 ₂ + AI2O3 + Si0 ₂ .

In one embodiment, at least one elementary insulating layer is made of a silico-aluminous refractory material, in particular a clay product. When the refractory part is the sole, this material is generally in the form of refractory concrete, in particular based on AZS grains, in particular AZS electrofused grains. The elementary insulating layer (s) made of this material provide a sealing function with respect to the molten glass.

At least one of the elementary insulating layers may consist of a silico-aluminous refractory material, in particular a clay product.

Fiber optics and sensors

The optical fiber 12 is preferably made of glass or sapphire. A sapphire fiber optic is well suited for high temperature regions.

The optical fiber preferably has a diameter of less than 200 µm, preferably less than 150 µm. Advantageously, its presence does not substantially affect the effectiveness of the insulating layer 18.

The optical fiber 12 extends between a proximal end 12 _r and a distal end l 2d. The proximal end 12 _r , or “inlet” of the optical fiber 12, is connected to the first interrogator 14i. The distal end l 2d can be free or be connected to a second interrogator l4 ₂ .

A part of the optical fiber 12, called the “measuring part” 20, extends in the refractory part or, preferably, in contact with a surface of the refractory part, preferably against the cold face 16 _f . The measurement part is the part which carries the sensors intended to read the temperatures. The rest of the optical fiber is used for the transmission of the signals, in particular between the interrogator (s) and the measurement part.

The measuring part 20 is fixed to the refractory part by one or more fixing points 21, preferably made of refractory cement, each fixing point having a length, along the optical fiber, preferably less than 5 cm, at 3 cm, 2 cm, 1 cm, or 0.5 cm.

In one embodiment, the measurement part 20 is not rectilinear between two fixing points, at ambient temperature. Preferably, the length of optical fiber between two successive fixing points is greater than 1.05 times, preferably greater than 1.1 times and / or preferably less than 1.5 times, preferably less than 1.4 times , preferably less than 1.3 times the distance between said fixing points. Advantageously, the optical fiber can thus adapt to dimensional variations of the refractory part on which it is fixed.

The measurement part 20 comprises one, preferably several sensors 22i, the index "i" designating a number identifying the sensor. The distance between two sensors 22; successive, along the optical fiber 12, can be constant or variable. It is preferably less than 50 cm, 30 cm, 20 cm, 10 cm, 5 cm, or even less than 3 cm, or 1 cm. The accuracy of the information provided by the interrogator is improved.

Preferably, a sensor, preferably each sensor, is a local modification of the structure of the optical fiber, which reflects at least part of the signal it receives from the interrogator.

In one embodiment, the optical fiber comprises several sensors, which each reflect a part of the interrogation signal I and allow another part to pass so that it can reach the other sensor or sensors arranged downstream. Each operational sensor thus responds to the interrogation signal, which makes it possible, with a single optical fiber, to obtain information coming from different regions of the refractory part. To determine the origin of a response signal, the interrogator may use the difference between the time at which the interrogation signal was issued and the time at which the response signal was received.

As illustrated in FIG. 3, each sensor can also reflect only part of the frequency spectrum (frequencies l in FIG. 3a) of the interrogation signal I injected by the interrogator 14 (in FIGS. 3a, 3b and 3c, " P "denotes the strength of the signals). The only analysis of the frequencies of the received signals thus allows to determine the origin of the response signals. In FIG. 3b, each sensor 22i has thus returned a frequency spectrum centered on a frequency l, which is specific to it. The interrogator can therefore deduce that the peak centered on the frequency l, comes from the sensor 22i.

Preferably, the sensor is configured to return a modified response signal as a function of temperature.

A sensor 22i, preferably each sensor 22i, is a Bragg grating.

Bragg grating optical fibers are known in applications other than glass furnaces.

In response to an interrogation signal I injected by the interrogator 14 through the proximal end of the optical fiber, each Bragg grating 22; returns a response signal Ri which is specific to it. Advantageously, a Bragg grating can therefore serve as a means of detecting the occurrence of a situation in which the Bragg grating is subjected to a temperature exceeding a threshold value, that is to say causing its destruction. A plurality of Bragg gratings of an optical fiber oriented to move away from the hot face of a refractory part therefore makes it possible to measure, in stages, the wear of this refractory part.

A Bragg grating also has the advantage of sending a response signal which depends on the temperature to which it is subjected. More precisely, each Bragg grating acts as an optical reflector at a specific wavelength. The heating of the Bragg grating however causes a modification of this wavelength. Of course, the wavelengths specific to the different Bragg gratings are determined so as to avoid any ambiguity on the Bragg gratings at the origin of a response signal. After having identified this original Bragg grating, the interrogator can determine the modification of the wavelength, or in a way equivalent the modification of the frequency, to determine the temperature of the Bragg grating of origin or an evolution of this temperature.

FIG. 3 c illustrates the particular, preferred case, in which the sensors are Bragg gratings. In response to the interrogation signal, they can return response signals centered on the frequencies l, at ambient temperature (FIG. 2b) and on frequencies l, offset from the frequencies l ,, respectively, the offset being a function of the temperature of the sensor 22i. In FIG. 3c, the peaks centered on the frequencies l, are in dashed lines and the peaks centered on the frequencies l, ’are in solid lines.

The use of Bragg grating optical fiber has proven to be particularly effective. Such an optical fiber is indeed compact, can incorporate several Bragg gratings, and therefore serve for the measurement of temperatures in different places, is not influenced by the electromagnetic environment and, being conventionally made up of a glass, does not come do not contaminate the molten glass bath if destroyed.

A Bragg grating can therefore be used as a means of measuring local temperature or the evolution of this temperature.

Wave arrangement

The measuring part of the optical fiber can extend substantially parallel to the hot face. When the refractory part is the side wall of the tank, the measurement part of the optical fiber may in particular extend in the direction of the height of the tank, preferably substantially vertically, more preferably along substantially the entire height of the tank, as in Figure 1.

Preferably, an array of optical fibers is available, preferably in the form of one or more sets of fibers, the measurement parts of which are parallel (FIGS. 1 and 4), for example in the form of two sets 32 and 34, the measurement parts of which are oriented at right angles, as shown in FIG. 4.

For the sake of clarity, only one fiber 12 has been illustrated in detail in FIG. 1.

Preferably, the density of sensors is greater than 3, preferably greater than 10, preferably greater than 50, preferably greater than 100 sensors per m ² of hot surface of the refractory part. In one embodiment, the network of optical fibers extends all around the side wall of the tank, preferably in a regular manner, so that the Bragg gratings of said optical fibers are distributed, preferably in a substantially homogeneous manner.

Preferably, the measuring portions of the optical fibers extend in the form of one or more layers, in particular planes.

In one embodiment, the sensors are arranged, on each optical fiber, at the intersections between the optical fibers. The sensor network is thus redundant.

Redundancy advantageously makes it possible to verify the correct functioning of the superimposed sensors, by comparing the measurements that they provide.

Optical fibers can be arranged at different depths, in particular in the form of overlapping layers of optical fibers. The depth is conventionally measured from the hot face, perpendicular to the hot face.

The number of superposed layers is not limiting and the density of layers can be greater than 1, or even greater than 2 layers per 10 cm of thickness (measured according to the direction of the depth) of the refractory part.

In a preferred embodiment, the measuring part extends at least in part, preferably completely outside the refractory part, and preferably against its cold face. It can in particular be sandwiched between the side wall of the tank and the thermally insulating layer 18, bearing on the cold face of the side wall (Figures 2c and 2d).

Preferably, it is housed in a recess 23 (FIG. 2c), preferably a groove, formed on the cold face of the side wall or on the hot face of the insulating layer 18 or on one of the grade faces of an insulating layer. elementary, preferably so as not to protrude from it.

The measurement part 20 can also pass through the insulating layer 18 (FIG. 2e).

In a preferred embodiment, it extends in sandwich between two successive elementary insulating layers of said insulating layer 18, as shown in FIG. 5. This embodiment is particularly advantageous for increasing the service life of the measurement part , while allowing reliable measurements. The measurement part may in particular extend within the insulating layer or within a single elementary insulating layer, that is to say exclusively in this layer.

In one embodiment, the measurement part 20 extends at least in part, preferably completely inside the refractory part. This embodiment is well suited when the refractory part is a block, for example a side block of the oven bowl.

Different techniques can be used to incorporate the measurement part into the refractory part.

In one embodiment, the refractory part or the insulating layer 18 or an elementary insulating layer is formed around the measuring part. The heat resistance of the optical fiber is however limited. This process is therefore well suited when the refractory part or the insulating layer 18 or the elementary insulating layer is produced by sintering, and in particular by sintering at low temperature, typically at bearing temperatures below 1200 ° C. Such a method can in particular include the following steps:

a) arrangement of the optical fiber so that a measurement part extends inside a mold;

b) preparation of a starting charge and introduction of said starting charge into the mold, so that it drowns said measuring part, and optionally compression of the starting charge, so as to obtain a preform;

c) sintering the preform at a temperature preferably between 400 ° C. and 1200 ° C.

Such a method advantageously allows close contact between the measurement part and the refractory part or the insulating layer 18 or said elementary insulating layer, which allows good heat exchange.

In one embodiment, the optical fiber is inserted, after manufacture of the refractory part or of the insulating layer 18 or of the elementary insulating layer, in a housing formed in said refractory part or said insulating layer 18 or said elementary insulating layer, respectively. The housing is preferably an elongated hole, straight or not, blind or through, preferably having a diameter interior substantially identical to that of optical fiber, but slightly higher to allow the introduction of optical fiber.

In one embodiment, the housing, preferably blind, does not pass, depending on the thickness, the refractory piece or said insulating layer 18 or said elementary insulating layer. After introduction into the housing, the distal end 12 _d therefore does not leave said refractory portion or said insulating layer 18 or said elementary insulating layer.

In another embodiment, the housing crosses the refractory part, between two faces, preferably between two lateral faces (opposite faces of adjacent blocks when the refractory part is a block) or between the upper face and the lower face of the refractory part.

The housing can also pass through the insulating layer 18 or said elementary insulating layer, between their two large faces.

Preferably, the difference between the outside diameter of the housing and the diameter of the optical fiber is less than 20%, preferably less than 10% of the diameter of the optical fiber.

The accommodation can be arranged according to a process comprising the following steps:

a ') arrangement of a wire inside a mold;

b ’) formation of the refractory part in the mold;

c ') extraction of the wire, which reveals a housing.

In particular, in step b ’), a bath of molten material can be poured into the mold, to produce a molten product.

The wire can extend through the mold so as to form, after being extracted from the refractory part, the insulating layer or the elementary insulating layer produced, a blind hole or a through hole.

The wire may for example be made of molybdenum. Preferably, it is covered with a non-stick coating, which facilitates its extraction from the refractory part or from the insulating layer or the elementary insulating layer, respectively.

Advantageously, when the refractory part is made of a molten material, it shrinks during its cooling, which facilitates the possible detachment of the wire. The wire can also be “sacrificial”, that is to say in a material which can be destroyed after manufacture of the refractory part or of the insulating layer or of the elementary insulating layer in which it has been placed, for example mechanically or by chemical attack.

Interrogator

Each interrogator conventionally comprises a transmitter / receiver 26 and a control module 28 (FIG. 1).

The transceiver 26 is adapted to transmit, at the input of the optical fiber 12, an interrogation signal I, for example a light signal, and to receive the response signal (s) Ri received from the sensor (s) 22i.

The control module 28 conventionally comprises a processor and a memory into which a computer program is loaded. With this computer program, the processor can control the emission of the interrogation signal and analyze the signals received in order to identify the signals from the sensors that have responded.

Preferably, the computer program makes it possible, when the sensors are Bragg gratings, to measure a frequency offset resulting from the local temperature of a Bragg gratings, consequently to evaluate a temperature and / or an evolution of 'a temperature compared to previous measurements, then send a message M containing information on this evaluation. This message can be sent to a central computer and / or be presented to an operator, for example on a screen and / or by activation of a light and / or by the emission of an audible signal.

Each interrogator is preferably placed at a distance from the hot face of the refractory part, more preferably at a distance from the cold face of the refractory part. It can in particular be arranged between the cold face of the refractory part and the hot face of the insulating layer 18, in contact with the cold face of the refractory part.

In one embodiment, each interrogator is outside of the insulating layer 18, that is to say on the side of the cold face of the insulating layer which is opposite to the hot face of the insulating layer. Advantageously, the interrogator is thus well protected from high temperatures. Preferably, first and second interrogators 14i and 14 ₂ are arranged at the entry and the exit of each fiber, that is to say at their proximal 12 _r and distal 12 _{d d} ends, respectively. For the sake of clarity, only the first and second interrogators 14i and 14 ₂ of the first fiber have been shown in FIGS. 1 and 4.

The second interrogator therefore receives the parts of the interrogation signal I injected by the first interrogator and which have not been reflected by the various sensors of the optical fiber. For example, if the optical fiber has only three sensors and if the interrogation signal and the response signals are those of FIGS. 3a and 3b, the second interrogator receives the signal shown in FIG. 3d.

The two interrogators therefore have a signal making it possible to identify the sensors having responded and therefore to evaluate the temperature or the temperature evolution for each sensor.

The second interrogator can also send an interrogation signal. In particular, if the optical fiber is damaged so that the signal from the first interrogator cannot reach the second interrogator, for example because the fiber has been cut, the first interrogator no longer receives any information from the sensors downstream of the cut , that is to say located between the cut and the second interrogator. The second interrogator can then interrogate these downstream sensors, by injecting an interrogation signal and analyzing the signal returned by these downstream sensors. The first interrogator can continue to interrogate the upstream sensors, by injecting an interrogation signal and analyzing the signal returned by these upstream sensors. The destruction of a sensor therefore has a limited effect on the functioning of the optical fiber.

The presence of two interrogators advantageously makes it possible, in the event of a break in the optical fiber, to obtain information relating to the sensors on each side of the break zone. It therefore improves the robustness of the device.

As is now clear, the invention provides a solution for accurately, real-time evaluation of a large number of temperatures in a glass furnace.

Of course, the invention is not limited to the embodiments described and shown, provided for illustrative purposes only. In particular, the invention is not limited to an optical fiber as a waveguide. Optical fiber glass is preferred because it excludes the risk of contamination of the molten glass. Other waveguides could however be considered. Preferably, the waveguide has the shape of a fiber preferably having a diameter less than 200 micrometers.

All the characteristics applicable to an optical fiber and described in this description are applicable to another type of waveguide.

The number of waveguides for a refractory part or an insulating layer or an elementary insulating layer, the number of waveguides connected to an interrogator and the shape of the refractory part, the insulating layer or said elementary insulating layers does not are not limiting. Several waveguides can be connected to the same interrogator.

The hot side of the block is not necessarily entirely in contact with the molten glass bath. It may not even be in contact with the molten glass, but only be exposed to the gaseous environment above this bath.

The invention is not limited to the bottom of the glass furnace either. The refractory part could be for example a feeder, a piece of superstructure (nose piece, vault block, ...), a forming piece (lip, ...) or a throat block.

Claims

1. Glassware oven comprising:

- a refractory part defining a hot face (16 _c ) in contact or intended to be in contact with molten glass or with a gaseous environment in contact with molten glass, and a cold face (16 _f ) spaced from said face hot, and

- a temperature measuring device comprising:

- a waveguide (12) comprising a measurement part (20) comprising at least one temperature measurement sensor (22;) configured to send a response signal in response to the injection of an interrogation signal in the waveguide; and

- an interrogator (14) connected to an input of the waveguide and configured to inject the interrogation signal (I) into said input, receive said response signal (Ri) returned by the sensor in response to the injection of said interrogation signal, analyzing the received response signal and transmitting a message according to said analysis;

oven in which the measurement part (20) is sandwiched between said cold face and a thermally insulating layer (18), or through said thermally insulating layer (18).

2. Oven according to claim 1, in which the measuring part (20) is housed in a housing formed on the cold face and / or in a housing formed on or in the thermally insulating layer (18) in contact with the cold face .

3. Oven according to any one of the preceding claims, in which the thermally insulating layer (18) comprises two elementary insulating layers (18i, 18 ₂ ) between which, or within one of which the measuring part (20) s extends.

4. Oven according to any one of the preceding claims, in which the measuring part (20) is fixed to the refractory part and / or to the thermally insulating layer (18), by at least one fixing point (21), said fixing point having a length, along the measuring part, of less than 5 cm.

5. Oven according to the immediately preceding claim, wherein the length of optical fiber between two successive attachment points is greater than 1.05 times the distance between said attachment points.

6. Oven according to any one of the preceding claims, in which the waveguide is an optical fiber and the sensor is a Bragg grating.

7. Oven according to the immediately preceding claim, in which the waveguide has a diameter of less than 200 micrometers.

8. Oven according to any one of the preceding claims, in which the refractory part is a side wall of a glass melting tank or a hearth or a feeder or a piece of superstructure or a forming piece or a groove block .

9. Oven according to any one of the preceding claims, comprising a sheet made up of a set of measuring parts of said waveguides and extending along a surface parallel to the hot face and / or to the cold face.

10. Oven according to the immediately preceding claim, comprising a glass melting tank comprising a side wall and a hearth, and in which the ply surrounds the side wall of the tank and / or in which the ply extends in a layer of concrete extending under the floor.

11. Oven according to any one of the two immediately preceding claims, in which the density of sensors in said sheet is greater than 3 sensors per m ² of hot face of the refractory part.

12. Oven according to any one of the three immediately preceding claims, comprising first and second said layers which extend parallel to one another, the distance between the first and second layers being greater than 1 cm, said parts for measuring the first ply crossing said measuring portions for the second ply when said first and second plies are observed in a direction normal to at least one of said first and second plies, a sensor being placed in the first ply and / or the second layer, at more than 50% of crossings.

13. Oven according to any one of the four immediately preceding claims, in which, at each crossing between measuring parts, sensors are arranged on each measuring part.

14. Oven according to any one of the preceding claims, comprising several said sensors, in contact or not, superimposed along a direction perpendicular to the hot face.

15. Oven according to any one of the preceding claims, in which each end of the waveguide is connected to a respective interrogator.