CN121487902A

CN121487902A - Glass furnace monitored by electrical reflection method

Info

Publication number: CN121487902A
Application number: CN202480036745.5A
Authority: CN
Inventors: 伊莎贝尔·安妮·卡博迪; 奥利维尔·西蒂; 蒂埃里·康萨莱斯; 埃米尔·洛佩兹; 刘子慷
Original assignee: Saint Gobain European Experimental And Research Center
Current assignee: Saint Gobain European Experimental And Research Center
Priority date: 2023-03-29
Filing date: 2024-03-29
Publication date: 2026-02-06
Also published as: FR3147131B1; EP4688674A1; FR3147131A1; WO2024200843A1

Abstract

The invention relates to a glass melting furnace comprising a device for monitoring the condition of a component of the furnace (30) by means of time-domain or frequency-domain electroreflectometry, the device comprising an array of linear electromagnetic waveguides (12) parallel to a hot face (37) and extending at a suitable distance such that, in use, the waveguides are at a temperature higher than 500 ℃ and lower than 1300 ℃, and comprising a plurality of discontinuities, called "basal discontinuities" (24), which are randomly distributed at least along the measuring component of the waveguides, and are capable of generating echoes with a magnitude greater than 0.5%, preferably greater than 1% and less than 30%, of the magnitude of the back lobe echo reflected by the output end of the waveguide, called "secondary basal echoes", or consisting of embossments or embossments resulting from an uneven segmentation of the dielectric material between the first and second electrical conductors, or local variations of the distance between the first and/or second electrical conductors and the dielectric material of the support, or the first and second electrical conductors and the first surrounding or surrounding structure. The number of basic discontinuities per meter of measuring member of the waveguide is greater than 10. The discontinuity may be a bead (23).

Description

Glass melting furnace monitored by electroreflectometry

Technical Field

The present invention relates to a glass manufacturing furnace equipped with an apparatus for monitoring the status of components of such a furnace, in particular the status of the refractory lining of the chamber of the furnace.

The invention also relates to a method for manufacturing such a furnace and to a method for monitoring the condition of the refractory lining of such a furnace.

Background

Many glass products are made by melting and refining a mixture of vitrifiable raw materials, including compounds such as oxides, carbonates, sulfates, and nitrates. These two steps are carried out in a furnace whose main constituent elements are refractory products capable of withstanding the thermal and mechanical stresses encountered in these furnaces, in particular the high temperatures. Accordingly, glass manufacturing furnaces typically include a large number of refractory products and are arranged in different locations depending on the properties of the refractory products. For each part of the furnace, the product selected will not cause defects that render the glass unusable (as this would reduce the yield) and will have sufficient tolerance over a long period of time to provide a satisfactory service life for the furnace.

Fig. 1 schematically illustrates a half cross-section of a glass manufacturing furnace 10. Specifically, the furnace 11, the metal structure 13 and the superstructure 16 are shown. The furnace 11 for containing molten glass includes vertical side walls 22 and a bottom 41. The side walls 22 are typically formed of side hearth bricks that extend the entire height of the hearth to an upper rim 29.

The superstructure 16 generally comprises an intermediate layer 17 at its base, the superstructure 16 resting on the metal structure through the intermediate layer 17, side walls 26, the side walls 26 resting on the intermediate layer 17, and a roof 28, the roof 28 also being formed of refractory bricks.

The heating system (not shown) comprises, for example, a burner, which is typically arranged in the side wall 26. The metal structure 13 is typically made of cast iron, which externally surrounds the side walls 22 of the furnace. Which bears the weight of the superstructure 16.

The hearth 11 and the superstructure 16 are parts of the furnace defining a chamber in which glass is melted. They define a hot face 37 in contact with the molten glass or its gaseous environment.

Since each component of the furnace has a hot face, the hot face is generally denoted by the term "object".

The furnace 11 and the superstructure 16 generally comprise multiple layers, i.e

-A first dense brick refractory layer, preferably having a porosity of less than 10%, preferably less than 5%, defining a hot face in contact with glass or its gaseous environment;

a second layer or "backing layer", made of a material different from that of the first layer, and being more porous.

The backing layer may comprise a first refractory sub-layer, known as a "barrier layer", for preventing infiltration of glass or for condensing glass vapors, and/or a second refractory sub-layer or "barrier layer", preferably comprising a porous refractory material, to achieve a suitable heat distribution in use.

The barrier layer is preferably an unshaped refractory product layer, in particular a layer of concrete or ramming mix. Typically, more than 90% of the number of particles of the barrier layer have a size (largest dimension) of less than or equal to 5mm to obtain a satisfactory surface finish and chemical composition such that the Al ₂O₃ weight content is at least 40%. The chemical composition of the barrier layer may be adjusted according to the type of glass so that it is sufficiently resistant to the molten glass.

The insulation layer is typically composed of unshaped silica alumina insulating refractory and/or refractory bricks or bricks. The thermal conductivity of the insulating refractory material, measured at 1000 ℃, is less than 7W/m.k, preferably less than 5W/m.k, and preferably less than or equal to 3W/m.k. Preferably, the porosity of the insulating refractory is greater than 15%, preferably greater than 20%, and more preferably greater than 30%. The porosity and thickness of the insulation layer are configured according to the desired thermal profile.

Conventionally, the dense brick of the first layer is made of a material that is resistant to contact with glass having a temperature higher than 600 ℃, or even higher than 1000 ℃, or indeed higher than 1200 ℃. More than 90% by weight of the dense brick may be composed of one or more oxides selected from the group consisting of ZrO ₂、Al₂O₃、SiO₂、Cr₂O₃、Y₂O₃ and CeO ₂. The dense brick preferably contains more than 90% ZrO ₂、Al₂O₃ and SiO ₂.

In use, the chamber of the furnace is subjected to extreme conditions, particularly corrosive and abrasive environments, which can lead to progressive wear. Particularly in the region in contact with the molten glass, the state of wear cannot be intuitively evaluated. In order to measure the residual thickness of a refractory brick, i.e. the distance between the hot face of the refractory brick and its cold face (i.e. the face opposite to the hot face), a probe hook is therefore typically used at the gas-melt interface. The disadvantage of this approach is that the furnace needs to be partially disassembled and then reassembled and only point measurements are provided.

Recently, WO2015147827 proposes a device which emits waves, in particular radar waves, through the tile. The reflected waves are analyzed when possible. In practice, this process takes a long time to perform and does not allow real-time monitoring.

WO2020025493 discloses an optical waveguide comprising a Bragg grating (Bragg grating) to measure the residual thickness of the bottom of a glass making furnace. The present inventors have tested the use of optical fibers and unexpectedly observed the occurrence of crystallization detrimental to the accuracy of the measurements and the mechanical strength of the optical fibers.

An apparatus for measuring the residual thickness of a blast furnace lining is also known from JPH11264706a or JP3395886B 2. The apparatus is very invasive, increasing the risk of contamination of the molten glass, in particular the risk of breakage of the first layer.

Thus, there is a need for a robust solution that is easy to implement and allows to evaluate the condition of the chamber of a glass manufacturing furnace continuously and in real time at any point, with good spatial resolution, without compromising the chamber lining and without increasing the risk of contamination of the molten glass bath.

It is an object of the present invention to at least partially meet this need.

Disclosure of Invention

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

-a glass melting chamber having a hot face exposed to the interior of the chamber;

-a device for monitoring the status of a component of the furnace (preferably a component of the chamber), referred to as "object", by means of an electrical time-domain or frequency-domain reflectometry, said device comprising:

An array of at least one, preferably a plurality of, filament-like electromagnetic waveguides, each comprising a first and a second (preferably metal) electrical conductor electrically isolated from each other (preferably electrically isolated by a dielectric material) between an input end and an output end,

The measuring means of the waveguide comprise a plurality of impedance discontinuities and extend parallel to the hot face and at a depth (distance behind said hot face with respect to the interior of the chamber) of more than 10cm, preferably more than 15cm, more than 20cm, and preferably less than 200cm, preferably less than 100cm,

-An interrogator electrically connected to the input and configured to inject an interrogation signal through the input, to receive a response signal reflected by the waveguide in response to the injection, to analyze the response signal and to send a message regarding the status of the object according to the analysis.

The inventors have found that this arrangement of the waveguide with respect to the object provides an excellent compromise between a limited attenuation of the response signal and a high robustness. Furthermore, the waveguide array allows monitoring of objects of any size, in particular the bottom of the furnace.

The object preferably comprises an assembly of refractory bricks defining a side wall, a top or a hot face of the furnace, preferably defining a hot face of the bottom and/or the top.

According to a first main embodiment, the impedance discontinuity comprises a "base discontinuity":

it is able to generate echoes, in particular when the length of the measuring element is less than 10 meters, in response to the injection of an interrogation signal, with an amplitude greater than 0.5%, preferably greater than 1%, preferably less than 30% of the amplitude of the terminal echo reflected by the output end of the waveguide, these echoes being referred to as "fundamental secondary echoes", and/or

-It is formed from:

-texturing an outer surface of the waveguide, and/or a dielectric material interposed between the first and second electrical conductors, and/or an embossment produced by texturing at least one of the first and second electrical conductors, and/or

-An embossment created by an irregular section of said dielectric material, preferably a pad made of dielectric material, preferably having a length of less than 10cm, preferably less than 5cm, preferably less than 3cm, more preferably less than 2cm, and/or more than 0.5cm, and/or

-A local variation of the distance between said first and second electrical conductor, and/or

-A change in distance between the first and/or second electrical conductor on the one hand and the dielectric material of a carrier, preferably made of a ceramic matrix composite, on the other hand, and/or

-A change in the structure and/or composition of the environment around or between said first and second electrical conductors, preferably a change in the structure and/or composition of the dielectric material of the carrier, preferably made of a ceramic matrix composite, preferably by randomly dispersing particles and/or fibres of the dielectric material within the carrier, in particular within the matrix of the ceramic matrix composite, or between the first and second electrical conductors.

Notably, the inventors have found that analysis of the fundamental secondary echo by either electrical Time Domain Reflectometry (TDR) or Frequency Domain Reflectometry (FDR) allows for real-time and continuous and accurate and reliable monitoring of the state of an object over a long period of time.

The base discontinuity can generate a base secondary echo in response to injection of the interrogation signal (i.e., in use) to monitor the state of the subject. For the purpose of this monitoring, the amplitude of the echo is preferably measured under similar or identical conditions as experienced by the measuring means when in the position of use, preferably at a temperature above 500 ℃, preferably above 600 ℃, preferably above 700 ℃, preferably above 800 ℃, and/or below 1300 ℃, preferably below 1200 ℃, more preferably below 1100 ℃.

Preferably, the basic discontinuities are randomly distributed at least along the measuring means of the waveguide, or even along the entire length of the waveguide. Advantageously, the random distribution avoids interference-related resonance effects.

Preferably, the base discontinuity is:

Texturing the outer surface of the waveguide, and/or the dielectric material interposed between the first and second electrical conductors, and/or the relief created by texturing at least one of the first and second electrical conductors, for example by abrasion and/or chemical etching, and/or

-Irregular segments of said dielectric material, preferably embossments produced by pads of dielectric material, for example preferably in the form of pad beads or cylinders with circular base, the length of the pads preferably being less than 10cm, preferably less than 5cm, preferably less than 3cm, more preferably less than 2cm, and/or more than 0.5cm, and/or

-A local change in the distance between the first electrical conductor and the second electrical conductor.

The conductor may be sandwiched between two webs of ceramic matrix composite material or fixed to the surface of the ceramic matrix composite material web, with the dielectric material (e.g., in the form of regular repeating units) preferably extending over one or more of the surfaces of the web. The dielectric material may be formed, for example, by depositing a paste and then curing.

In one embodiment, the above-described interlayers have a thickness greater than 5mm, greater than 8mm, greater than 10mm, and/or less than 50mm.

In one embodiment, the fabric, preferably each of the above-described fabrics, has a thickness of greater than 0.5mm, greater than 1mm, and/or less than 10mm, less than 5mm, or less than 2 mm.

Preferably, more than 80% of said fundamental secondary echoes are generated by textured generated fundamental discontinuities.

The one or more pads are preferably arranged less than 1mm from the first electrical conductor and/or from the second electrical conductor, and are preferably in contact with the first electrical conductor and/or the second electrical conductor.

Preferably, in the measuring component, one or more pads are provided on the first electrical conductor and/or the second electrical conductor.

In one embodiment, in the measuring component, pads in the form of beads of a pad and made of a dielectric material are provided on the first electrical conductor and/or on the second electrical conductor, and a plurality of pads are arranged to together form a segmented protective coating extending over the entire length of the measuring component of the waveguide.

The one or more pads are preferably spacers made of a dielectric material arranged to hold the first electrical conductor away from the second electrical conductor.

In one embodiment, one or more pads are movable relative to the first electrical conductor and/or the second electrical conductor.

Preferably, one or more of the pads is made of a thermally and electrically insulating material. The thermally insulating material preferably has a thermal conductivity of less than 30W/m.k, less than 20W/m.k, less than 10W/m.k or even less than 5W/m.k at a temperature between 20 ℃ and 1000 ℃.

Preferably, one or more of the pads has a melting point above 300 ℃, above 500 ℃ or above 1000 ℃ and is preferably made of a material selected from mica, mica derivatives, titanium, barium, mullite, cordierite and alumina.

In one embodiment, the discontinuity, preferably the base discontinuity, is created by affixing the measurement component to the carrier. In particular, the carrier can surround the measuring component in a coating manner or can hold the measuring component. In particular, the measuring member may be sandwiched between two fabrics, preferably between woven fabrics reinforced by a ceramic matrix. Such fabric irregularities and irregularities of the matrix of the ceramic matrix composite advantageously and unexpectedly allow the creation of basic discontinuities.

Preferably, the impedance discontinuities are spaced apart from each other by a distance measured along the waveguide that is at least 10 times, preferably at least 15 times, and preferably at least 20 times the reference wavelength. The reference wavelength is equal to the propagation speed of the interrogation signal (about 200000km/s for electromagnetic waves) divided by the frequency of the highest peak of the frequency spectrum of the interrogation signal.

The invention also relates to a method for manufacturing a furnace according to the first main embodiment, said method comprising the steps of:

i) Altering the measurement component of at least one waveguide (preferably a coaxial cable) to create a random distribution of fundamental discontinuities along the waveguide;

ii) integrating the at least one altered waveguide into or against a wall of a chamber of a glass manufacturing furnace;

iii) Connecting the interrogator to an input of the at least one modified waveguide, the at least one modified waveguide forming the filament-like electromagnetic waveguide,

To obtain a glass manufacturing furnace according to the first main embodiment.

Those skilled in the art know how to alter waveguides, particularly coaxial cables, to create a fundamental discontinuity. Via simple experimentation they will be able to easily verify whether the echo returned by the discontinuity forms the fundamental secondary echo and adjust the discontinuity by adding texturing, for example, in case the discontinuity returns an echo of insufficient amplitude to make the echo the fundamental secondary echo.

Preferably, step i) comprises, and preferably consists of, a modification of the outer surface of the waveguide (preferably of the coaxial cable), preferably by texturing and/or segmenting the outer surface of the waveguide, for example obtained by threading the pad.

The waveguide changed in step a) may be a commercial waveguide.

Step i) may be replaced by step i '), in which step i') the basic discontinuity is created at the same time as the waveguide is manufactured. In particular, the base discontinuity may be produced in particular by:

By texturing and/or segmenting the outer surface of the waveguide, e.g. by threading a pad onto the waveguide, and

By varying the composition of the dielectric material interposed between the first and second electrical conductors, and/or

By changing the composition of at least one of the first and second electrical conductors, and/or

By creating an embossment on a surface of the dielectric material and/or on at least one of the first and second electrical conductors.

According to a second main embodiment, the furnace further comprises one or more, and preferably all, of the following optional features:

a) The measurement members of each waveguide of the array extend parallel to the hot face at a distance such that, in use, i.e. when the furnace is operating normally, the measurement members are at a temperature above 500 ℃, preferably above 600 ℃, preferably above 700 ℃, preferably above 800 ℃, and/or below 1300 ℃, preferably below 1200 ℃, more preferably below 1100 ℃;

b) The maximum distance between the two measurement components of any two waveguides of the array is greater than 20cm, preferably greater than 30cm, preferably greater than 50cm, preferably greater than 70cm, preferably greater than 90cm, and preferably less than 500cm;

c) Inserting at least one waveguide, preferably each waveguide of the array into an aperture in the object, the aperture configured to provide space for thermal expansion of the waveguides;

d) The equivalent diameter of at least one waveguide, preferably the measurement component of each waveguide in the array is greater than 0.6mm, preferably greater than 0.8mm, preferably greater than 1mm, and less than 50mm, preferably less than 20mm, preferably less than 10mm, and preferably less than 5mm;

e) The separation distance of the first and second electrical conductors of the measuring component of at least one waveguide, preferably each waveguide, of the array is greater than 0.3mm, preferably greater than 0.4mm, preferably greater than 0.5mm, and less than 30mm, preferably less than 10mm, preferably less than 5mm, preferably less than 3mm, which improves reliability and spatial resolution;

f) The measuring member has the following number of bends:

-if the length of the measuring member is less than 3 meters, the measuring member has less than 2 bends per meter length;

-if the length of the measuring member is greater than or equal to 3 meters, then there are less than 1 bend per meter, preferably less than 0.5 bends per meter, more preferably less than 0.1 bends per meter, which improves the integration of the waveguide while minimizing the risk of the waveguide breaking during its installation in the furnace;

the waveguides, preferably the measurement component of each waveguide, preferably does not contain a bend;

The maximum curvature of the measuring part is such that its radius of curvature is at least 3 times, preferably at least 5 times, preferably at least 10 times the equivalent diameter of the measuring part, which reduces the mechanical stress on the measuring part.

Preferably, the measuring means of at least one waveguide, preferably of each waveguide, is mounted so as to be slidable with respect to the object and/or with respect to the carrier.

Through research into numerous parameters, the inventors have found that this combination of features provides a solution that meets certain limitations of glass manufacturing furnaces. In particular, this solution allows to achieve the following aims:

-limiting the risk of damaging the waveguide at installation;

monitoring large-sized objects, such as the bottom of a furnace;

-high robustness in use;

-good spatial resolution;

-high measurement reliability;

Real-time monitoring over the whole life of the furnace without weakening the object and without increasing the risk of contamination of the molten glass bath.

According to a third main embodiment, the first and second conductors are fixed to or integrated into a carrier, preferably a floor-like carrier, preferably a carrier formed of a ceramic matrix composite, and are fixed to or integrated into the composite, preferably by means of an interface layer or refractory filaments, nails or tape. By "integrated" is meant that the first conductor and the second conductor are incorporated into a composite material, such as weft filaments or warp filaments, which become the fabric of the composite material.

The fixing of the conductor in or on the carrier allows the conductor to be protected. The carrier is preferably arranged between the first layer and the backing layer.

In a first preferred configuration, the carrier comprises and is preferably formed of a ceramic matrix composite, and preferably the first conductor and the second conductor are integrated into the fabric of the ceramic matrix composite. The conductive filaments, preferably arranged substantially parallel and spaced apart by a predetermined distance, may for example form some weft filaments. The other filaments of the fabric (except for the first and second conductors) are preferably made of a dielectric material to avoid any electrical contact or short between the conductive filaments.

In one embodiment, other filaments (or "non-conductive filaments") made of a dielectric material may be randomly altered, such as by abrasion or chemical etching, to create random base discontinuities.

In an additional or alternative embodiment, the first conductor and the second conductor are randomly altered, for example by abrasion or chemical etching, to generate random base discontinuities.

In one embodiment, at least one of the first conductor and the second conductor is physically associated with one or more filaments made of a dielectric material, the filaments being wound, for example randomly, to generate random base discontinuities.

In one embodiment, filaments made of a dielectric material are randomly added to the fabric.

In one embodiment, to generate random discontinuities, in particular basic discontinuities, the first conductor and the second conductor are woven into the fabric in such a way that the distance between said conductors varies along the conductors. Preferably, the distance between two of said base discontinuities is less than 10cm, preferably less than 5cm, and/or greater than 0.5cm, and preferably greater than 1cm. Preferably, the distance between two consecutive points of the first conductor and the second conductor, preferably the distance between two consecutive weft yarns, is less than 10cm, preferably less than 5cm, and/or greater than 0.5cm, and preferably greater than 1cm, by being located above or below the weft or warp filaments (optionally crossing) of the woven fabric.

In one embodiment, to generate random basic discontinuities, randomly sized and/or randomly shaped and/or randomly sized particles and/or fibers and/or spatially randomly distributed particles and/or fibers are arranged in contact with the fabric prior to impregnation with the matrix precursor. Irregularly textured textile webs may also be used as fabrics.

In the second configuration, the first and second conductors are fixed to a surface of the carrier, and preferably the carrier comprises, and preferably is formed of, a ceramic matrix composite.

According to one possible embodiment, at least one waveguide, preferably a conductor of each waveguide, preferably a measurement component is fixed to the carrier by means of an interface layer. The interfacial layer is a layer made of a material having a Coefficient of Thermal Expansion (CTE) that is intermediate between that of the carrier, in particular the CTE of the ceramic matrix of the carrier, and the CTE of the material from which the conductor is made. Preferably, the interfacial layer comprises or even consists of NiCrAlY.

According to another possible embodiment, at least one waveguide, preferably a conductor of each waveguide, preferably a measuring component is attached or fixed to a carrier, preferably in the form of a plate, by means of fire resistant filaments, nails or tape.

In one embodiment, the measuring component is protected by a coating made of a dielectric material, preferably a polymer or more preferably a ceramic, which surrounds the conductors, which are preferably separated by the dielectric material. The coating may be straight or curved. The coating may be flexible or rigid to give the measuring or even the transmission part a shape.

In one embodiment, as shown in fig. 12, a carrier precursor, preferably formed from a precursor 40' of a ceramic matrix composite (typically a prepreg), is wrapped around the first and second conductors, at least in the measurement component. The instrumented carrier precursor or instrumented carrier is preferably inserted into a protective coating 27, preferably ceramic, before or after curing of the matrix precursor.

It is particularly advantageous to fix the measuring component of the waveguide to or integrate into the ceramic matrix composite, not only because the ceramic matrix composite protects the measuring component, but also because by construction, the ceramic matrix composite has an irregular microstructure that can create many basic discontinuities even when the ceramic matrix composite comprises a woven cloth.

According to a fourth main embodiment, the measuring means of at least one waveguide, preferably each waveguide, is movable such that its dimensions can be changed under the influence of temperature changes in use. Preferably, the measuring member is slidably mounted with respect to the object and preferably slidably mounted in the housing, in particular in an aperture formed in the object or preferably in the carrier.

It is also preferred that the housing retains a space for thermal expansion, which space is preferably formed by removing a sacrificial material around which at least a portion of the object or carrier is formed.

Sliding may also be caused by the presence of solid lubricant (preferably graphite) around the measurement component.

Due to the incompatibility between the material of the object or carrier defining the housing on the one hand and the measuring component on the other hand, for example due to the high porosity of the material of the object defining the housing, the measuring component may also not adhere to the wall of the housing.

Sliding may also be caused by the insertion of the measuring component into the protective coating (preferably a non-segmented coating). Indeed, segmenting the protective coating by placing a series of dielectric pad beads along the measurement component tends to enhance the attenuation of the signal.

The invention also relates to a method for manufacturing a furnace according to the invention, comprising, for at least one waveguide of the array, preferably for each waveguide, the following successive steps:

1) The sacrificial material is interposed between:

measuring component of a waveguide, and

-An object or a precursor of an object, or a carrier, in particular a ceramic matrix composite or carrier precursor, then

2) In case the sacrificial material has been inserted in a precursor of the object or a precursor of the carrier, respectively, the sacrificial material is removed after or simultaneously with the manufacturing of the object or carrier to create said space for measuring the expansion of the component.

In one embodiment, the sacrificial material is a material that covers a sacrificial coating of the measurement component, and to interpose the sacrificial material,

-Manufacturing an object or a carrier around the measurement component, preferably by casting a precursor of the object around the measurement component and subsequently sintering, or by inserting the measurement component into a precursor of the carrier and subsequently sintering a precursor of the carrier around the measurement component;

-forming a housing in the form of a recess or hole (or aperture), optionally a through slot or through hole, in the object or in the precursor of the object or in the carrier precursor, then inserting the measuring component into the housing, then filling the housing with an unshaped refractory product (i.e. a powder or paste), preferably a refractory concrete, wherein the refractory concrete contains a binder, preferably a hydraulic binder, preferably cement, and is capable of being cured by activation of the binder, and then curing the unshaped refractory product.

The precursor of the object may be a preform for sintering or a powdery mixture that is capable of being solidified by a chemical reaction. The carrier precursor may be a ceramic matrix composite precursor, or "prepreg," comprising a fabric and a matrix precursor impregnating the fabric.

The measuring component provided with the sacrificial coating can be embedded in the precursor of the object or carrier at the time of its manufacture. Alternatively, the housing may be formed in the object or in a precursor of the object or in the carrier or in a carrier precursor, and the measuring component provided with the sacrificial coating may be embedded in the unshaped refractory material.

In one embodiment, the sacrificial material is a filler material that is independent of the waveguide (i.e., unlike the sacrificial cladding, the sacrificial material is not initially fixed to the waveguide), and in order to insert the sacrificial material,

-Forming a housing in the form of a recess or hole, optionally a through slot or through hole, in the object or in the precursor of the object or in the carrier precursor, and then

-Inserting the measuring component into the housing, and then

Filling the housing with a filling material to embed the measuring component, the amount of filling material being such that an expansion space can be formed, then

Filling the remainder of the shell with said unshaped refractory product, preferably refractory concrete, and then

-Curing the unshaped refractory product.

In step 2), the sacrificial material is preferably removed using a heat treatment, preferably a heat treatment using a precursor for consolidating the object or carrier, preferably by sintering. The sacrificial material is preferably removed by heating at a temperature preferably between 400 ℃ and 1200 ℃ during furnace warm-up and/or during sintering of the unshaped refractory product or object precursor or carrier precursor. Sintering may be caused by the temperature rise of the furnace.

The sacrificial material may be removed by evaporation or combustion.

Thus, the sacrificial material leaves room for thermal expansion.

Preferably, the sacrificial material is an organic material, preferably a polymer. Upon degradation, such sacrificial materials advantageously generate residual carbon that limits oxidation of the first conductor and the second conductor, allowing for its use in an oxidizing atmosphere.

The method of manufacture may further comprise one or more of the following optional and preferred features:

Step 1) and/or step 2) are performed in situ (i.e. in a component of a furnace in which the measurement component is intended to be used in the furnace);

-forming the shell in the carrier or in a precursor of the carrier, but may also be formed in the backing layer of the object or in a precursor of the backing layer;

The sacrificial coating of the waveguides, preferably of each waveguide, is made of a polymer, preferably of a halogen-free and/or nitrogen-free and/or silicon-free polymer, preferably of a polyolefin, preferably of one of polyethylene or a derivative thereof;

-the filler material is a resin;

-removing the sacrificial material while the precursor of the object or the carrier is cured to obtain said object or said carrier, respectively.

In one embodiment, step 1) comprises the steps of:

-placing the array precursor in its use position, i.e. arranging one or more measurement components in the use position required during operation of the furnace;

preparing a starting filler having the desired composition of the object or support, considering only refractory oxides in this respect;

-depositing a starting filler to embed the array precursor and obtain a precursor of the object or carrier.

In one embodiment, at least one, preferably each, measuring component is protected by a protective coating, preferably a ceramic protective coating. The sacrificial coating covers the protective coating.

According to a fifth main embodiment, the waveguide comprises a protective cladding protecting the first and second electrical conductors.

The protective coating may be rigidly fixed to the conductor as long as the protective coating is segmented or forms a rigid sheath that serves as a housing for the waveguide. After the sheath has been placed in its use position, the waveguide may be inserted into the sheath. In particular, the sheath may be included in the object at the time of manufacturing the object, for example, placed in place before being embedded in the concrete composition of the object.

Preferably, the waveguide is free to move within the sheath. The protective coating may also form an expansion space as described above.

The rigid sheath may advantageously guide the waveguide to have a predetermined shape (e.g., a straight or curved shape) or over a significant length during its insertion.

Preferably, the waveguide is protected by two protective coatings, namely a segmented protective coating, preferably formed by a plurality of abutment pads, and a rigid protective coating, which acts as a housing for the waveguide. The segmented protective coating may be produced, for example, from several perforated cushion beads.

The invention also relates to a method of manufacturing a glass manufacturing furnace according to the invention, comprising, for at least one waveguide in an array, and preferably for each waveguide in the array, the steps of:

A) Preparing a precursor of a ceramic matrix composite comprising a ceramic matrix precursor, preferably in the form of a plate, and integrating a measuring component of the waveguide into or onto the ceramic matrix composite precursor to obtain an instrumented carrier precursor;

b) Curing and/or firing, preferably sintering, the instrumented carrier precursor, preferably at an elevated temperature of the furnace to obtain the instrumented carrier by consolidation of a ceramic matrix precursor, preferably in the form of an instrumented plate;

C) If step C) is followed by step B), the instrumented carrier is installed, or if step C) is followed by step B), the instrumented carrier precursor is installed, preferably between a backing layer defining a hot face and a heating system of the furnace, and preferably substantially parallel to said hot face.

Preferably, step a) preferably comprises the steps of:

a) Preparing a ceramic matrix precursor in the form of a slurry comprising ceramic particles and/or precursors of ceramic particles, the material of which has a dielectric constant or relative permittivity of greater than 3 and/or less than 30, and preferably less than 15, relative to vacuum at 25 ℃ and atmospheric pressure (preferably measured at 1 MHz);

b) Independently of step a), the first and second electrical conductors of the measuring component are fixed or integrated into a fabric, preferably in the form of one or more filament textiles or filaments, preferably ceramic filaments, the material of the fabric being a material having a dielectric constant or relative permittivity of more than 3 and/or less than 30, and preferably less than 15, with respect to vacuum, at 25 ℃ and atmospheric pressure (preferably measured at 1 Mhz);

c) The fabric is impregnated with the slurry.

Before or preferably after step B), a connector is installed that is capable of electrically connecting the conductor to the interrogator.

In one embodiment, the measuring component or even the transmission component is protected by said coating before it is fixed to the carrier or integrated into the carrier.

In one embodiment, in step B), the firing is such that the temperature of the instrumented carrier precursor is from 400 ℃ to 1200 ℃.

In a specific embodiment, step B) is performed in an oven or furnace, preferably under air, 0, preferably under a controlled atmosphere, prior to step C).

In one embodiment, in step C), the instrumented carrier precursor is mounted on or in a precursor of the object, and in step B), the instrumented carrier precursor is consolidated to convert it to the object while converting the ceramic matrix precursor to a ceramic matrix and a precursor of the object.

In one embodiment, in step C), an instrumented carrier or an instrumented carrier precursor, preferably in the form of a plate, is arranged between:

-said measuring member, and

-An object or a precursor of an object.

Of course, the features of the various main aspects may be combined. Preferably, the features of the various main aspects are combined.

Regardless of the primary embodiment, the waveguide array of the glass manufacturing furnace according to the present invention may also have one or more of the following optional and preferred features:

the waveguide array is located at least partially, preferably entirely:

A refractory back layer, which is located behind the first layer formed by the assembly of refractory bricks defining the hot face of the object, or

-Within a refractory sublayer of said backing layer;

-the measuring means of the waveguides, and preferably of each waveguide, are located in the back layer or in a sub-layer of the back layer, preferably behind a blocking sub-layer;

The sub-layer is an insulating sub-layer in contact with the cold face of the object and serving to define the thermal profile of the lining, or preferably a blocking sub-layer for neutralising the molten glass in the event of penetration of the furnace (in particular the bottom of the furnace);

Preferably, when the object is the bottom of the furnace, the measuring means of the waveguides, and preferably of each waveguide, are located between the barrier and the insulating sublayers;

The measuring means of the waveguides of the array, and preferably of each waveguide of the array, extend into a housing, preferably in the form of an aperture formed in the object and defining a space for thermal expansion of said waveguides;

The space for thermal expansion is configured such that, in use, the measuring component of the waveguide is not compressed by the object due to changes in dimensions of the object and the measuring component caused by temperature changes;

preferably, the ratio of the equivalent diameter of the housing to the equivalent diameter of the measuring means is greater than 1.05, preferably greater than 1.10, preferably greater than 1.20, and/or less than 3.00, and preferably less than 2.50;

-the housing is an aperture having a diameter smaller than the thickness of the layer or sub-layer in which the measuring component is placed;

-the diameter of the aperture is less than 70%, or even less than 50% of the thickness of the layer or sub-layer;

The measuring means of each waveguide preferably not comprising a curved waveguide is at least partially, preferably completely parallel to the measuring means of the other waveguide;

The measuring means of at least one waveguide of the array, and preferably the measuring means of each waveguide, do not comprise a bend;

-the maximum distance between the measurement parts of any two waveguides is less than 200cm;

The plurality of measuring components of the plurality of waveguides together form a web extending over a curved or flat surface (preferably a flat surface);

-the measurement members of the mesh are spaced from each other by a distance of more than lcm, more than 5cm, more than 10cm, more than 20cm, and/or less than 100cm, less than 80cm or less than 50 cm;

-the measuring members of the net are parallel or cross each other without touching each other;

The furnace comprises more than 1, more than 2, preferably more than 3, preferably more than 5 of said nets, preferably parallel to each other, preferably parallel to the hot face, and preferably regularly spaced in a direction perpendicular to the hot face, the distance between two consecutive nets preferably being less than 10cm, 5cm or 2cm, which advantageously allows to evaluate the heat flux through the object;

At least one measuring member of the array, and preferably more than half of the measuring members, extend in use in a direction perpendicular to the flow direction of the molten glass;

-a radius of curvature of the measuring means of the waveguides of the array, and preferably the radius of curvature of each waveguide of the array is at least 3 times, preferably at least 5 times, and preferably at least 10 times or more the equivalent diameter of the measuring means at each point;

The waveguides of the array, and preferably each waveguide, are exposed on the cold face (the face opposite to the hot face) of the object or on the side of the object that is colder than said hot face (in particular when the object is the bottom of the furnace).

Those skilled in the art know how to define the dimensions of the housing for the measurement component to reserve the appropriate space for thermal expansion. For example, in the case of a furnace bottom, they will consider the thermal gradient of the bottom, the thermal expansion coefficients of the slab and the measurement components, and their dimensions.

The dimensions of the housing are also designed such that the object and the waveguide can expand independently of each other, and in particular such that extension or retraction of the object does not stress the waveguide, or vice versa.

Regardless of the primary implementation, the waveguides of the array, preferably each waveguide, may also have one or more of the following optional and preferred features:

The waveguide fulfils the condition of Rayleigh (Rayleigh) scattering, which makes it easier to locate the region of the reflected fundamental secondary echo;

at least in the measuring means, at least one spacer is arranged between two adjacent pads, and preferably between the pads of each pair of two adjacent pads, the at least one spacer being made of an electrically insulating material that is more deformable than the material of the pads;

-said spacers, and preferably each said spacer:

Made of elastically compressible material in the manner of a spring, and/or

Comprising and/or consisting of an organic material, preferably a polymeric material, for example a polyethylene or silicone based polymeric material, preferably selected from elastomers, thermoplastic materials and heat shrinkable materials, and for example in the form of foam or adhesive;

The length of the measuring means and/or the waveguide is greater than 1 meter, preferably greater than 2 meters, preferably greater than 3 meters, or even greater than 10 meters, and/or less than 30 meters, and preferably less than 20 meters;

the length of the transfer member is preferably greater than 0.1 meter, and/or less than 5 meters, or even less than 2 meters;

The first and second electrical conductors are parallel, which allows robustness, efficiency and low cost to be achieved;

the first and second electrical conductors are coaxial, which limits the volume and increases the stability of the distance between the conductors, the dielectric material holding the two coaxial conductors in place;

The first electrical conductor and the second electrical conductor are rectilinear, which facilitates integration into the object;

-the equivalent diameter of the first and second conductors is greater than 0.4mm, greater than 0.5mm, preferably greater than 1mm, and/or less than 50mm, preferably less than 20mm, preferably less than 10mm, and preferably less than 5mm, which allows for improved signal quality (low attenuation) while reducing the risk of the object becoming weakened or broken;

the first electrical conductor and the second electrical conductor are separated from each other by a dielectric material belonging to the object and, for example, to the electrical insulation layer;

The first and second electrical conductors comprise or preferably consist of a refractory metal or metal alloy, such as silver, available at up to 800 ℃, or inconel (e.g. alloy 625 and alloy 690), available at up to 1100 ℃, or FeCr (e.g. KANTHAL APM), available at up to 1425 ℃, as supplied by Kanthal, or a noble metal, preferably selected from platinum, tungsten, gold, palladium, rhodium, ruthenium, iridium, or an alloy of these elements, the platinum possibly being doped, preferably with 0.001% to 5% of oxides of zirconium, hafnium, calcium, magnesium or yttrium;

a dielectric material separating the first conductor and the second conductor, comprising or consisting of an oxide of at least one element selected from Al, zr, mg, ca, ti and Si;

-the material from which the first and second electrical conductors are made has a resistivity of less than 10 micro ohm-meters in the temperature range of the environment in which the measuring component is used, preferably between 20 ℃ and 1000 ℃;

The dielectric material separating the first and second conductors has a dielectric constant or relative permittivity of more than 3 and/or less than 30 and preferably less than 15 with respect to vacuum at 25 ℃ and atmospheric pressure (preferably measured at 1 MHz);

-the dielectric material comprises an oxide of at least one element selected from Al, zr, mg, ca, ti and Si;

At least a part of the measuring component, preferably at least in the region of the component of the waveguide that is not inside the object, is protected by a protective member, for example in the form of a tube or perforated or slotted brick, and preferably a protective coating, preferably a ceramic coating, partially and preferably completely surrounding the measuring component;

-the protective coating is made of an oxide of at least one element selected from Al, zr, mg, ca, ti and Si;

The waveguide is connected to the interrogator at each of its two ends;

The waveguide is exposed on the cold face (the face opposite to the hot face) of the object or on the side of the object that is colder than said hot face;

the first and second conductors are fixed to a plate-like carrier (preferably formed of a ceramic matrix composite), preferably by an interface layer or refractory filaments, nails or tape, or integrated into said composite.

Regardless of the primary embodiment, at least one spacer made of a material that is more deformable than the material of the pads is preferably arranged between two adjacent pads. Preferably, at least in the measuring component, a spacer is arranged between the pads of each pair of adjacent pads. Preferably, the material of the spacer is resiliently compressible in the manner of a spring. The spacers, and preferably each spacer, are preferably in the form of a spring or in the form of a washer. The spacers, and preferably each spacer, comprise or consist of an organic material, preferably a polymeric material, preferably a thermoplastic material or a heat shrinkable material, or a polymeric foam.

Preferably, in the measuring component, the spacer is arranged through the first electrical conductor and/or the second electrical conductor.

The insertion of spacers between the pads advantageously makes it possible to ensure a minimum spacing between the pads, in particular when the waveguide is curved. In particular, the spacer limits the risk of breakage when the waveguide is wound, for example, onto a mandrel or into a coil (in view of its transport) and when the waveguide is placed in its use position.

Regardless of the primary implementation, the interrogator may also have one or more of the following optional and preferred features:

-the interrogator is configured to determine the temperature, wear level and/or wear rate of the object based on the analysis of the response signal;

The interrogator is configured to predict the occurrence of a penetration or immersion of molten glass into the object, or a sudden movement or degradation of the lining;

the furnace preferably comprises at least one thermocouple arranged at a distance of less than 10cm from the waveguides (preferably from each waveguide), for example in the region of the furnace between 500 ℃ and 1500 ℃ when the furnace is in use, to calibrate the waveguides for indirect temperature measurement.

The invention also relates to a method for monitoring the condition of an object of a glass manufacturing furnace according to the invention, said method comprising the steps of:

a. manufacturing a glass manufacturing furnace according to the present invention;

b. for each waveguide, controlling an interrogator coupled to the waveguide such that the interrogator injects an interrogation signal through an input of the waveguide;

c. the response signal is analyzed to determine information about the state of the object in the region of the measuring part of the waveguide.

According to a particular embodiment, the information related to the condition of the object is the remaining thickness of the refractory material or the temperature at one or more points on the object.

Drawings

Other features and advantages of the present invention will become more apparent upon reading the following detailed description and studying the drawings, wherein:

FIG. 1 shows a schematic half-section of a glass manufacturing furnace;

Fig. 2 schematically shows an example of a monitoring device according to the invention in a use position;

FIG. 3 illustrates various possible embodiments of a waveguide including a pad bead;

FIG. 4 shows the bottom of the glass manufacturing furnace according to the present invention as viewed from above;

FIG. 5 shows in cross section the conventional structure of the bottom of a glass manufacturing furnace;

FIG. 6 shows in cross section the bottom of a glass manufacturing furnace according to the invention in a first preferred embodiment;

fig. 7 shows in cross section the bottom of a glass manufacturing furnace according to the invention in a second embodiment;

FIG. 8 shows in cross section an array of waveguides in the top of a glass manufacturing furnace according to the present invention in a preferred embodiment;

Fig. 9 shows one example of a response signal;

FIG. 10 illustrates a carrier plate incorporating a measurement component according to one embodiment of the invention;

FIG. 11 shows a carrier in the form of a plate incorporating a measurement component according to another embodiment of the invention;

fig. 12 shows the manufacture of a carrier by winding a carrier precursor around a measurement member.

The same reference numbers will be used throughout the drawings to refer to the same or like elements.

Detailed Description

Definition of the definition

"Subject" refers to a refractory component of a furnace equipped with a monitoring device. The object is preferably a lining of the furnace or an element of said first layer (seen from the interior of the furnace), which is typically obtained by assembling bricks, such as the side walls, top or bottom of the furnace. The first refractory layer is typically made of a fused or densely sintered material to be resistant to temperature and also to corrosion by the molten glass and/or its vapors.

The "hot face" is the face of the object that is exposed to the space in the furnace that, in use, contains or is used to contain molten glass. The hot face may alternatively be used to contact the molten glass and/or the gaseous environment above the molten glass. Thus, a hot face is the face of an object that is subject to or is used to experience the highest temperature. The hot face of all the bricks of the side wall of the glass-melting furnace can also be considered to be "hot face" in a broad sense. The upper surface of the bottom may also be referred to as the "hot side". The adjective "hot" is used for clarity.

Conventionally, the "thickness" of an object is its dimension measured in a direction perpendicular to its hot face or in the "depth" direction. For example, for a hearth side brick in contact with molten glass, the thickness is measured in a substantially horizontal direction directed toward the molten glass bath. For the furnace bottom, the thickness is measured in the vertical direction.

Two objects have a "substantially identical composition" when at least 80%, preferably at least 90%, of their components are identical.

Concrete is generally composed of a set of coarse particles, greater than 50 μm in size, typically between 50 μm and 25mm, bonded by a matrix that ensures a substantially continuous structure between the coarse particles. The matrix consists of "matrix particles" having a size of less than or equal to 50 μm.

Activation is the process of curing most fresh concrete. Fresh concrete is generally produced from a mixture of particles comprising hydraulic binder, and preferably additionally more than 3% by weight of water, which is wetted with water or another liquid. For shaping, if the mixture is not self-compacting, the fresh concrete is preferably cast, vibration cast, or even sprayed.

"Hydraulic binder" means a binder that, when activated, generally causes hydration to cure and harden at room temperature. Cement is a hydraulic binder. Alumina cement is an example of cement. Calcium aluminate cement is an example of alumina cement.

Refractory "ramming mix" is a refractory mix containing chemical and/or ceramic and/or organic binders, which is usually shaped (possibly after wetting) by ramming or compacting or ramming, either manually or using suitable mechanical means. Preferably, the particulate mixture is non-wetting ("dry" process) or wetted with less than 3wt% water.

A "carrier" is a component added to an object and the measurement component of one or more waveguides is arranged on or in the carrier. The carrier physically protects the measurement component, preferably creating a base discontinuity, and preferably allows the measurement component to slide, especially under the influence of temperature.

A carrier or carrier precursor is sometimes considered "instrumented" when it carries the measurement components of at least one waveguide.

The panel typically has two substantially parallel major faces, the thickness between the two major faces typically being less than 1/2, or even less than 1/3, or even less than 1/5, or even less than 1/10, or even less than 1/100 of the width of the major faces. The plate may be planar or curved. The shape of the plate-like carrier is preferably configured to match the shape it is used to the object to which it is fixed.

"Ceramic matrix composite" or "CMC" generally refers to a product composed of fibers and/or filaments bonded together by a ceramic matrix, preferably at least 30vol% of the CMC. The choice of fibers and/or filaments depends on the environment in which the ceramic matrix composite must be placed, in particular on the conditions in terms of temperature, corrosion, thermal cycling and expansion, and on the nature of the refractory components of the furnace to be equipped.

The layout selected for the fibers and/or filaments forming the structure of the reinforcing matrix depends on the desired shape of the ceramic matrix composite and the ease with which the waveguide must be secured thereto. For example, a stack of woven fabrics or webs of fibers is well suited for simple plates, filament winding is well suited for plates with rotational geometry, and filament placement is well suited for complex shapes of large dimensions.

Ceramic matrix composites are typically manufactured by heating, preferably to over 600 ℃, and preferably to over 700 ℃, and preferably by sintering.

The fibers and/or filaments are typically in the form of a fabric. CMC may then be considered as a "ceramic matrix fabric".

The fabric may be:

ordered two-dimensional structure of fibres or filaments, in particular knitted, woven or textile, or

Random two-dimensional structure of fibers or filaments, which is not preferred.

In particular, unlike fibrous mats, the organization of the fibers or filaments of a fibrous mat is random in all three dimensions of space.

"Fiber" is a filament that has a length that is greater than 5 times its equivalent diameter. The "diameter" of a fiber is the diameter of a disk of the same area as the cross-section at its mid-length.

A "filament" is an aggregate of fibers comprising more than 10 and preferably less than 500000 fibers in cross section, and the length of the filament is greater than 5 times its diameter or more.

"Filament-like" means "having the general shape of a filament". For example, the cable has a filiform shape. Strips or "ribbons" are considered to be filaments. The length of the object having a filament-like shape is preferably 10 times, 100 times or 1000 times or more than 10000 times its width (i.e., the largest dimension of the object in a plane perpendicular to its length direction).

"Waveguide" refers to a filiform transmission line different from the object, which is capable of guiding electromagnetic waves derived from very high frequency electrical signals for measurement by an electrical time-domain or frequency-domain reflection method. The waveguide generally comprises at least two electrical conductors electrically isolated from each other and extending in the length direction of the waveguide. The interrogation signal is typically a change in the potential difference between the electrical conductors. The interrogation signal is injected at the input end of the waveguide and then propagates in the form of electromagnetic waves. Changes in electrical impedance may cause partial reflection of such waves. The reflected response signal is also a time dependent change in the potential difference between the electrical conductors.

The term "echo" is used to denote the portion of the response signal that is reflected by:

discontinuity points (secondary echoes),

An input of a waveguide, wherein a connector of the waveguide is connected to an interrogator (emits an echo), or

The output of the waveguide (terminal echo 4-see fig. 9).

Thus, the secondary echo is a response to a discontinuity in the interrogation signal. The secondary echo may be a "noise" secondary echo 5, a "base" secondary echo 6 or a "hard" secondary echo 7 (fig. 9).

The noise secondary echo is a secondary echo having an amplitude of less than or equal to 0.5% of the amplitude of the terminal echo, and preferably greater than 0.0001% of the amplitude of the terminal echo, preferably greater than 0.01% of the amplitude of the terminal echo, and preferably greater than 0.1% of the amplitude of the terminal echo. Noise secondary echoes are typically generated by "noise" discontinuities caused by imperfections in the waveguide, particularly imperfections generated during the manufacture of the waveguide.

Since the noise secondary echo has a low amplitude, the noise secondary echo is attenuated very rapidly. In many cases, the noise secondary echo cannot accurately monitor the changes associated with the measurement, for example when the temperature rises or the humidity is high.

The fundamental secondary echo is a secondary echo generated by a "fundamental" discontinuity that is typically created by an intentional modification of the waveguide (e.g., by texturing or adding a pad). Preferably, the amplitude of the fundamental secondary echo is less than the amplitude of the terminal echo, and preferably less than 90%, preferably less than 70%, preferably less than 50%, and preferably less than 30% of the amplitude of the terminal echo. When the length of the measurement component is less than 10 meters, the amplitude of the fundamental secondary echo is preferably greater than 0.5% of the amplitude of the terminal echo, preferably greater than 1% and less than 30% of the amplitude of the terminal echo.

The amplitude of the fundamental secondary echo may be greater than 2%, 3% or 5%, or even 10% of the amplitude of the terminal echo reflected by the output end of the waveguide.

The hard secondary echo is a secondary echo having an amplitude greater than or equal to 30% of the amplitude of the terminal echo. Hard secondary echoes are typically isolated and generated by "hard" discontinuities, which are typically created by significant or abrupt changes in the waveguide structure, such as by unexpected degradation of the waveguide (e.g., due to cracking (non-fracture)). Such hard local discontinuities do not allow to measure disturbances or changes to the environment other than the position of the hard discontinuities by analyzing the hard secondary echoes. Thus, hard local discontinuities do not allow for measuring changes over the entire length of the measuring component.

However, the studies recently conducted by the inventors have demonstrated that if the number of discontinuities generating hard secondary echoes per meter of the waveguide measurement component is greater than 10, greater than 15, greater than 20, greater than 30, greater than 40, greater than 50, and preferably less than 10000, and if these discontinuities are randomly distributed, the hard secondary echoes generated by the discontinuities can form a basic secondary echo that can be used to monitor the state of the component of the furnace by an electrical time domain or frequency domain reflectometry.

A "discontinuity" or "impedance discontinuity" is a portion of a waveguide that is capable of reflecting a particular echo, preferably in the form of a small change in potential, in response to an interrogation signal. The echo is changed when the impedance of the discontinuity changes, and in particular when it is subjected to a change in the nature of its local environment (i.e. in the region of the discontinuity).

In particular, when the shape of the waveguide and/or the local temperature and/or the nature of the local environment (i.e. around the discontinuity) is changed, the impedance of the discontinuity may be changed. If only one of the factors that causes the discontinuity to change, such as the local temperature, changes, there will therefore be a relationship between the impedance (and thus the echo) and the value of that factor.

In particular, the discontinuity may be generated by a local variation of the structure and/or composition of the waveguide, and in particular by a local variation of one of the conductors of the waveguide and/or of the dielectric arranged between said conductors.

By "sacrificial coating" is meant a coating that is capable of at least partially decomposing, preferably by heat treatment.

For clarity, a distinction is made between a protective cladding for being preserved in use and a sacrificial cladding or "temporary" cladding, the sacrificial cladding being used to form a space for thermal expansion of the waveguide, the sacrificial cladding thus being used to be removed.

The equivalent diameter of a waveguide or a measuring part or a conductor or a housing is the maximum cross-sectional diameter of the waveguide or the measuring part or the conductor or the housing, respectively, taking into account that the cross-sectional diameter measured for a cross-section is the diameter of a disk having the same area as the cross-section along each cross-section (i.e. a cross-section perpendicular to the longitudinal direction) of the waveguide or the measuring part or the conductor or the housing, respectively.

When the cross section remains unchanged, the equivalent diameter is thus equal to the cross section diameter, irrespective of the cross section in question.

A "bend" is a region of a measuring component that changes direction by more than 45 ° over a length of less than 80 cm.

A "precursor" of an element is an object that is transformed into the element during the furnace fabrication process. For example, a preform of an object is a precursor of the object that is converted into the object during sintering.

"Preform" means a component shaped or prefabricated from a particulate mixture, such as concrete (typically by casting and vibration) or a ramming mixture (typically by ramming), and intended to be rammed by heat treatment and, for example, by sintering. Methods for manufacturing preforms are well known to those skilled in the art. Typically, particles of refractory powder are mixed with a temporary binder and the mixture is formed into the desired shape.

The adjectives "first" and "second" are used merely for clarity of presentation.

Unless otherwise indicated, "conductor" refers to either the first or second electrical conductor of the waveguide.

"Local" or "locally" is used to define a feature or action that is related to only a portion of the waveguide, such as a feature or action that is related to a portion of a length less than 5cm, 1cm, or 1 mm. Thus, a "local" change in a property means that the value of the property changes within that portion, for example by more than 5% or more than 10%. The variation may be, for example, less than 500%.

In general, "ceramic material" refers to a material that is neither metal nor organic. In a preferred embodiment, oxide glass and carbon (in various forms, whether crystalline or not) are considered ceramic materials.

The terms "comprising," "including," and "having" are to be construed broadly and in a non-limiting sense.

Detailed Description

The present invention utilizes the well-known principles of electrical time domain reflectometry (E-TDR) or electrical frequency domain reflectometry (E-FDR).

Typically, the transmitter transmits an interrogation signal in the form of pulses into the conductive medium. The conductive medium returns a reflected response signal, which is then analyzed to infer information about the conductive medium therefrom.

In particular, the temperature to which the measuring component is subjected depends on the environment of the object, in particular the molten glass or its vapour, but also on the thickness of the material separating the object from the environment. When the thickness at a point on the object decreases, the measurement component can see that its local response changes when it receives an interrogation signal.

This local reaction allows the interrogator to be informed of the reduction in thickness of the object, or even of the penetration of the molten glass into the object at the point of problem.

Monitoring device

Electromagnetic waveguide

Waveguide 12 (fig. 2) takes the form of a transmission line, such as the general form of a strip or cable, that extends from an input end 12e to an output end 12s. The waveguide 12 includes:

a measuring member 14 comprising a discontinuity for the measurement, and

A transmission means 15 for connecting the measurement means 14 to an interrogator 18.

The measurement component is designed to withstand the temperatures to which it is subjected in use, and preferably to 200 ℃, and preferably to 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, 1100 ℃ or 1200 ℃.

The length of the waveguide, and preferably the length of the measurement component, is preferably greater than 1m, preferably greater than 2m, preferably greater than 5m, preferably greater than 10m, greater than 15m, greater than 20m, and/or less than 200m, or even less than 100m, preferably less than 50m.

Preferably, the conductors, and preferably each conductor, or even the waveguide, have a length of less than 10mm, less than 5mm, and/or preferably greater than 0.4mm, preferably greater than 0.5mm, preferably greater than 1 mm:

-equivalent diameter, or

For conductors or waveguides in the form of strips, thickness.

The waveguide includes first electrical conductor 12 ₁ and second electrical conductor 12 ₂, and first electrical conductor 12 ₁ and second electrical conductor 12 ₂ take the form of, for example, a cable, cable assembly, or ribbon including one or more wires.

Each conductor has:

an input (i.e. at the input of the waveguide) electrically connected to a corresponding terminal of the interrogator 18, and

-A free output at the output of the waveguide.

The outputs are not electrically connected to each other and thus the conductors do not form a circuit (e.g. a circuit through which a direct or alternating current flows in a resistance measuring device).

The material of the conductor is preferably a conductive metal such as Al, cu or steel or a metal alloy. The material of the conductor may also be ceramic or cermet. In particular, for applications in high temperature environments, the conductor may be made of:

an inconel (e.g., alloy 625 and alloy 690), which can be used at temperatures up to 1100C,

The presence of platinum in the form of a platinum alloy,

FeCr (e.g., KANTHAL APM) supplied by Kanthal, which can be used at temperatures up to 1425 ℃,

The composition of tungsten and tungsten,

The presence of rhodium in the reaction chamber,

The presence of ruthenium (ru),

Palladium, or

Iridium.

Conductors made of metals coated with the conductive refractory oxides SnO ₂ or Cr ₂O₃ -MgO spinel or perovskite or metalloid carbide or metal can be adapted for very high temperatures.

Preferably, the material of the conductor is a noble metal, preferably selected from platinum, gold, palladium, rhodium and iridium.

The resistivity of the first and second conductors is preferably less than 10 ohm.m over the temperature range of the environment (preferably between 20 ℃ and 1000 ℃).

According to a first embodiment, each conductor is formed by a cable formed by one or more wires. The first and second conductors are non-coaxial and are kept away from each other by a dielectric insulator having a resistivity that is preferably 10, 50, 100 or 1000 times greater than the resistivity of the conductors.

According to a second preferred embodiment, the waveguide is formed by a coaxial cable, for example a coaxial cable with a BNC connector, comprising an inner wire or sleeve forming a first conductor and an outer sleeve forming a second conductor, the two sleeves being separated by an electrically isolating intermediate sleeve. Preferably, the material of the intermediate sleeve comprises and preferably consists of an oxide of at least one element selected from Al, zr, mg, ca, ti and Si.

In one embodiment, the waveguide is formed of at least two linear conductors, preferably platinum cables, such as FKS platinum cables supplied by Ogussa, placed in parallel and spaced apart by a distance greater than 1mm, preferably greater than 2mm, and/or preferably less than 20 mm. Refractory pad beads, preferably alumina pad beads, are threaded onto the conductors, preferably through the first and second through holes through which the first and second conductors pass.

The length of the waveguide and preferably the length of the measurement component is preferably greater than 1m, preferably greater than 2m, preferably greater than 3m, or even greater than 10m, and/or less than 30m, or even less than 20m.

The two conductors are preferably parallel, optionally except in the region of the discontinuity. Local defects in the parallel structure may be formed, thereby creating discontinuities, particularly basic discontinuities.

Protective coating

Preferably, the waveguide and/or each conductor may be inserted into a protective coating, which may optionally be segmented, to protect the conductor from heat and/or corrosion and/or chemical attack, in particular before being fixed to or integrated into the carrier, preferably in the form of a plate.

The protective coating may in particular be made of ceramic, in particular alumina, in particular for environments with temperatures greater than 400 ℃.

The protective coating is preferably made of a material having a coefficient of thermal expansion substantially the same as the material of the conductor.

Preferably, the thermal expansion coefficient of the waveguide, preferably at least the measurement component, is substantially the same as the thermal expansion coefficient of the portion of the object housing the measurement component (+/-20%, preferably +/-10%).

The protective coating may be straight or curved and extends around the measurement component. The coating may be used to give the measuring part or even the transmission part a curved shape.

Carrier body

The waveguide, in particular at least the measuring component, may also be fixed to a carrier 40 (see fig. 10 or fig. 2), preferably in the form of a plate, which itself is in contact with the object 30.

A given carrier, in particular in the form of a plate, may carry a plurality of measurement components, or even all measurement components of a waveguide array.

The support is preferably made at least in part of a material formed of filaments and/or fibers bonded together by a ceramic matrix (to form a so-called "ceramic matrix composite").

The choice of fibers and/or filaments and ceramic matrix will depend on the environment in which the ceramic matrix composite must be placed, in particular on the conditions in terms of temperature, corrosion, thermal cycling and expansion, and on the nature of the object to be monitored.

The coefficient of thermal expansion of the ceramic matrix composite may be adjusted using techniques well known to those skilled in the art, particularly by adjusting the composition of the ceramic matrix composite.

Preferably, the ceramic matrix composite has a yield strength of greater than 3MPa, preferably greater than 6MPa, and preferably greater than 10MPa, as measured using the 3-point loading geometry specified in ASTM C1341-13. Advantageously, the mechanical strength thereof, in particular the impact strength thereof, is thereby improved.

For example, a stack of textile fabrics or webs of fibers or filaments is well suited for simple plates, filament winding is well suited for plates with a rotating geometry, and filament placement is well suited for complex shapes of large dimensions.

The carrier is particularly useful when the object belongs to or forms a side wall of the furnace.

The layout selected for the fibers or filaments depends on the desired shape of the ceramic matrix composite and the ease with which the conductors must be secured to or inserted into the ceramic matrix composite. The ceramic matrix composite preferably has a crush strength of greater than 5MPa, preferably greater than 10MPa, and/or a thermal conductivity between 20 ℃ and 500 ℃ of greater than 2.0 w.m ^-1.K^-1.

Preferably, the ceramic matrix composite comprises more than 80%, more than 90%, more than 95% or substantially 100% by weight of one or more of the following oxides Al ₂O₃、ZrO₂、HfO₂、Cr₂O₃, mgO, caO and SiO ₂.

In one embodiment, the ceramic matrix composite has the following chemical composition in weight percent of oxides such that Al ₂O₃ + SiO₂ > 80%, preferably greater than 85%, preferably greater than 90%, or even greater than 95%.

In one embodiment, the matrix comprises and preferably consists of, in terms of greater than 80%, greater than 90%, greater than 95% and preferably substantially 100% by weight thereof, one or more compounds selected from the group consisting of Al ₂O₃、ZrO₂、Cr₂O₃, mgO, caO and SiO ₂.

Preferably, the volume of the fibers or filaments is greater than 25%, preferably greater than 30%, preferably greater than 40%, preferably greater than 50%, preferably greater than 60%, and/or less than 70% of the volume of the CMC material, ignoring its porosity, the complement required to reach 100% being formed by the ceramic matrix bonding the fibers together. The diameter of the fibers, i.e. measured along the midpoint of the fibers, averaged over all fibers, is preferably between 3 micrometers and 30 micrometers, and preferably between 5 micrometers and 25 micrometers.

Preferably, the carrier takes the form of a (planar or non-planar) plate and has a preferably constant average thickness between its major faces, preferably less than 40mm, preferably less than 32mm, preferably less than 28mm, preferably less than 22mm, preferably less than 20mm, or even less than 18mm or 15mm or 10mm, and/or preferably greater than 1mm, preferably greater than 2mm, or even greater than 3mm, or greater than 5mm.

The surface area of the main face of the carrier is preferably greater than 100cm ², preferably greater than 200cm ², preferably greater than 300cm ², preferably greater than 400cm ², and/or less than 20000cm ², preferably less than 15000cm ², or even less than 10000cm ².

In one embodiment, the carrier is in the form of a roll prior to being mounted against the object. In one embodiment, the carrier is fixed to the cold face of the subject, and preferably the carrier comprises an apertured region, i.e. a region through which a plurality of apertures pass, to facilitate heat exchange with the cold face.

The object may in particular be a first layer formed by dense, fused or sintered bricks.

In one embodiment, the carrier is bonded to the cold side of the object. Preferably, the adhesive used to fix the waveguide to the carrier and/or fix the carrier to the object is selected from a mixture of ceramic powder and binder, which is preferably applied in liquid form.

Preferably, the powder is a powder of alumina and/or silica and/or mullite. Preferably, the binder is selected from the group consisting of colloidal silica, sodium silicate, organic resins, organic binders, and mixtures thereof. The adhesive used may also be a commercial adhesive, such as Fixwool Adhesive FX from Unifrax corporation.

In one embodiment, the measuring component of the waveguide is embedded within the ceramic matrix composite or a precursor of said ceramic matrix composite, and is preferably sandwiched between two fabrics of said composite.

According to a first particular embodiment, the measuring component of the waveguide is fixed to the carrier by means of an interface layer. The interfacial layer may be an adhesive comprising a thermosetting, thermoplastic or elastomeric polymer, particularly when the temperature of the face of the object containing the carrier, particularly the cold face, is less than or equal to 400 ℃.

In one embodiment, the measuring component of the waveguide is fixed to the carrier by means of a refractory filament, staple or tape.

In one embodiment shown in fig. 11, the first and second conductors of the measuring component are integrated into the filament arrangement of the ceramic matrix composite or the precursor of the ceramic matrix composite, for example as weft filaments, warp filaments or knitting filaments. The first conductor and the second conductor are substantially parallel and separated by a predetermined distance. Preferably, the distance separating the conductors is greater than 0.3mm, preferably greater than 0.4mm, preferably greater than 0.5mm, and less than 30mm, preferably less than 10mm, preferably less than 5mm, and preferably less than 3mm.

In order to maintain the distance between the two conductors, at least one filament or even a plurality of filaments made of a dielectric material may be interposed between the first conductor and the second conductor of the waveguide. In one embodiment, a given carrier may carry multiple measurement components of various waveguides.

In one embodiment, the measurement component is contained in a ceramic protective coating incorporated into the carrier during its manufacture, or in a channel formed in the carrier during or after its manufacture.

Spacing piece

Regardless of the embodiment, direct electrical contact between the two conductors may be avoided by interposing a dielectric insulator 25 or "spacer" that is made of, for example, mica derivatives, titanium, barium, mullite, cordierite, or alumina.

The dielectric insulator may be one-piece or composed of an assembly of multiple dielectric pads. Preferably, a dielectric pad is interposed between the conductors, the pad preferably taking the form of a pad bead threaded onto at least one conductor, and preferably both conductors.

The pad will be described in more detail in the remainder of the specification.

The predetermined distance between the two electrical conductors is preferably substantially constant.

When the first and second conductors are integrated into the fabric of the ceramic matrix composite and form constituent filaments of the fabric (e.g., weft or warp filaments), the spacer may be formed from filaments made of a dielectric material, which may also be constituent of the fabric. For example, if the first and second conductors are weft or warp filaments, they may be separated by one or more other weft or warp filaments (filaments 25 in fig. 11) respectively made of a dielectric material.

Discontinuity point

The number of discontinuities, in particular the number of basic discontinuities, per meter of waveguide measurement means is preferably more than 10, more than 15, more than 20, more than 30, more than 40 or more than 50, and/or less than 10000, less than 1000, less than 500 or less than 100. It is thus advantageously possible to evaluate the properties of the environment of the measuring component over substantially the entire length of the measuring component and with good accuracy.

Preferably, the distance between any two consecutive discontinuities 24 along the waveguide 12, in particular between any two consecutive base discontinuities, is less than 1/100 of the wavelength of the interrogation signal (the wavelength of the interrogation signal is equal to the propagation speed of the interrogation signal (about 200000 km/s for electromagnetic waves) divided by the frequency of the highest peak in the frequency spectrum of the interrogation signal).

The distance is preferably greater than 10mm, 15mm or 20mm, and/or less than 100mm or 50mm.

Thereby advantageously increasing the sensitivity of messages communicated by the interrogator.

The use of discontinuities reflecting small changes in the potential makes it possible to avoid the need to create large discontinuities that will tend to strongly attenuate the interrogation signal and thus prevent the entire length of the measuring component of the waveguide from being monitored. Preferably, more than 50%, preferably more than 80%, and preferably more than 90% of the discontinuities reflect the fundamental secondary echo and/or the noise secondary echo, and preferably reflect the fundamental secondary echo.

The use of these small random potential variations is counter to the development of electroreflectometry because these variations are considered detrimental. Preferably, the discontinuity is randomly added to the waveguide.

The discontinuities are variable, i.e. they do not all reflect the same echo when they receive the same interrogation signal. It is also preferred that the variation of the discontinuity points, in particular the variation of the underlying discontinuity points, is random.

The discontinuity 24, in particular the basic discontinuity, may be obtained by modifying the surface of one or both conductors and/or dielectric insulation and/or the material from which it/they is made, for example by abrasion or by chemical etching, or by adding dopants to the material, or by adding pads to modify the surface.

In one embodiment, the waveguide is formed by a coaxial cable, for example a coaxial cable with a BNC connector, comprising a wire forming a first conductor and an outer sleeve forming a second conductor, the two sleeves being separated by a spacer in the form of an electrically isolating intermediate sleeve. By varying the surface finish of the insulating sleeve, for example by creating roughness, discontinuities 24, particularly base discontinuities, can be created. Another way involves creating random discontinuities on the outer casing, in particular basic discontinuities, for example by abrasion (without interrupting the electrical conduction within the outer casing).

In one embodiment, some of the discontinuities, in particular the base discontinuities, are irregularities on the surface of the spacer, which irregularities are preferably formed facing the conductor and are preferably formed in at least one region of the spacer in contact with the conductor. Advantageously, texturing the region allows random discontinuities to be generated.

The discontinuities 24, in particular the underlying discontinuities, may also be created by varying the surface finish (texturing) of the dielectric insulation 25, for example by creating roughness, for example by abrasion, which is preferably random.

Preferably, texturing comprises creating embossments having a height of greater than 0.05mm, preferably greater than 0.1mm, preferably greater than 0.2mm, preferably greater than 0.4mm, preferably greater than 0.5mm, or even greater than 0.8mm, and/or less than 3mm, less than 2mm, or less than 1 mm.

The density of embossments, i.e. the number of embossments per textured unit area, in particular the unit area of the surface of the dielectric material and/or the unit area of the surface of at least one of the first and second electrical conductor, is preferably greater than 1/10000 mm ², preferably greater than 1/1000 mm ², preferably greater than 0.5/100 mm ² (or 0.5/cm ²), and/or less than 10/mm ², preferably less than 1/mm ², or preferably less than 1/10 mm ² (or 10/cm ²).

The predetermined distance between the two electrical conductors is preferably substantially constant. The two conductors are preferably parallel, optionally except in the region of the discontinuity. Local defects in the parallel structure may be formed, thereby creating discontinuities, particularly basic discontinuities.

Preferably, the base discontinuity is created by varying the following distances:

The distance between two electrical conductors, or

-A distance between the first and/or second electrical conductor on the one hand and the dielectric material of the carrier on the other hand, which distance varies by more than 0.1mm over a length of the measuring part of less than 2mm, preferably less than 1mm.

Preferably, in order to create the discontinuity, the dielectric pad is arranged in contact with the first conductor and the second conductor.

The dielectric pad, and in particular the pad bead, may have a length measured along the waveguide of greater than 10mm, 15mm or 20mm, and/or less than 100mm or 50 mm.

The dielectric pad, in particular the pad bead, preferably has a width of more than 1mm, 2mm or 3mm and/or less than 10mm or 5mm, i.e. a maximum dimension in a plane transverse to its length direction.

Fig. 3 shows various possible embodiments of the dielectric pad. In particular, fig. 3 shows the following embodiment, wherein:

-the pad beads 23 are threaded on only one of the first and second conductors (3E) or on both the first and second conductors (3A to 3D);

The pad beads 23 are threaded to form a protective coating 27, the protective coating 27 sectioning (3A, 3C to 3E) or not sectioning (3B) the two first and second conductors (3A to 3D) to protect one (3E) or both conductors;

-threading beads 23 with the same shape (3A, 3D) or different shapes (3B, 3C, 3E);

-pad beads 23 with the penetrating surface textured in the same way (3A to 3c,3 e) or not (3D);

-one or more conductors are symmetrical (3A, 3B, 3C, 3D) or asymmetrical (3E) with respect to the axis of each bead 23;

one or more conductors parallel to (3A-3E) or not to the axis of each bead 23.

The pad also facilitates identification of the area where the fundamental secondary echo is generated and can thus be used as an identification mark.

Preferably, the composition and/or structure of the carrier may also be changed near or around or between the first and second electrical conductors in order to create the base discontinuity. In particular, the composition and/or structure of the carrier may vary by more than 10% over the length of the measuring part of less than 1 mm. For example, the structure of the carrier may be locally deformed to create depressions or elevations, e.g. mechanically or by local melting, and/or the composition of the carrier may be changed.

The carrier may be a carrier fixed to the waveguide, for example to a carrier made of CMC.

For example, the waveguide may be fixed to a carrier that is not of uniform material quality but contains variations that are exhibited by the presence of holes (through holes or isolated holes/blind holes) that originate, for example, from the inclusion of woven fabric in the carrier. The irregular consistency of the filaments creates random underlying discontinuities.

For example, the waveguide is fixed to or embedded in a carrier comprising inclusions, each inclusion (e.g. in the form of particles or fibres) arranged along the measurement component resulting in a change in the composition of the carrier.

Random distribution of discontinuity points

Preferably, the discontinuities are irregularly distributed along the waveguide. Preferably, the discontinuities, in particular the base discontinuities, are randomly distributed along the waveguide.

The random nature of the distribution or amplitude of the discontinuities advantageously avoids the risk of producing an accumulation of secondary echoes of the same period, which accumulation may strongly attenuate the interrogation signal.

The dielectric pads may have the same or different shapes and/or sizes and/or be made of the same or different materials. Even though the dielectric pads appear identical, none of the pads are identical to the other pads.

Variations in the shape and composition of the pad, particularly the shape and composition of the pad bead, and the position of the pad bead relative to the conductor, allow for the generation of randomized discontinuities. Thus, the underlying discontinuities can be randomly generated.

In order to generate random discontinuities, in particular basic discontinuities, in embodiments in which the first and second conductors of the measuring component (e.g. as weft filaments, warp filaments or knitted filaments) are integrated into the filament arrangement of the carrier made of ceramic matrix composite material, the first and second conductors and/or other filaments (or non-conductive filaments) made of dielectric material may be randomly changed, e.g. by abrasion or chemical etching. Filaments made of a dielectric material may also or alternatively be randomly wrapped around the first conductor and/or the second conductor. Filaments and/or fibers and/or particles made of a dielectric material may also or alternatively be randomly added to the fabric. In addition to or as an alternative to the other possibilities described above, particles of variable size or shape or unevenly placed particles may also be brought into contact with the fabric prior to impregnation. The choice made in terms of the size or shape of the particles, the texture applied or the length of the fibers allows random discontinuities to be created.

The conductor may also or alternatively be arranged in contact with a mat of irregularly textured textiles or randomly arranged fibers prior to impregnation with the matrix precursor and subsequent curing to form the instrumented carrier.

Rayleigh scattering condition

The waveguide preferably satisfies the condition of rayleigh scattering. Advantageously, the region with the reflected fundamental secondary echo can be easily located.

Preferably, the base discontinuities 24 are spaced apart from each other by a distance measured along the waveguide that is at least 10 times, preferably at least 15 times, and preferably at least 20 times the reference wavelength. The reference wavelength is equal to the propagation speed of the interrogation signal (about 200000km/s for electromagnetic waves) divided by the frequency of the highest peak of the frequency spectrum of the interrogation signal.

The distance may in particular be defined by the length of the dielectric pad, in particular the length of the pad bead that is threaded onto the waveguide. In order to generate a sufficient basic secondary echo, the length of the pad is preferably configured according to the reference frequency (inverse of the reference wavelength) to satisfy the condition of rayleigh scattering.

For example, a pad (e.g., a pad bead) having a length of less than 3cm, preferably less than 2cm or 1cm, is very suitable for a reference wavelength of about 15 cm. For example, for an interrogation signal at a frequency of 1GHz, an alumina pad bead of less than 10mm length threaded onto a platinum wire produces a secondary echo of lower amplitude, while a pad bead of greater than 100mm length produces a hard secondary echo.

In the case of basic discontinuities and under the condition of Rayleigh scattering, accurate measurements can be made over a length of more than 1m, preferably more than 2m, preferably more than 5m, preferably more than 10m, more than 15m, or more than 20m, and/or less than 500m, for example over the entire length of the measurement component.

Waveguide array

Preferably, the array comprises a plurality of measuring means, preferably parallel to each other and to the hot face of the object, such that the density of discrete points, preferably the density of basic discrete points, per m ² of hot face area is greater than 3, preferably greater than 10, preferably greater than 50, preferably greater than 100, preferably greater than 500, preferably greater than 800 discrete points, and/or less than 1000000, preferably less than 500000, preferably less than 100000, preferably less than 50000, preferably less than 10000, preferably less than 5000, preferably less than 2000 discrete points. Thereby, the reliability of the analysis by the interrogator is improved.

Preferably, the measurement component forms a mesh extending over a curved or planar surface (preferably a planar surface), each waveguide preferably being connected to its own interrogator.

The waveguide array may comprise more than 1, more than 2, preferably more than 3, and preferably more than 5 of said webs, preferably parallel to each other and preferably regularly spaced from each other in a direction perpendicular to the surface of the component.

In fig. 4, two nets 32 and 34 are shown, which in this case are used to equip the furnace bottom 41.

In one embodiment, at least two waveguides intersect at different depths, measured from the hot face perpendicular to the hot face. Since the characteristics of the stacked waveguides are known, it is advantageously possible to define the temperature distribution in the depth direction and/or the extent to which the thickness of the object (e.g. the furnace bottom) evaluated at each point of the hot face under which a plurality of waveguides are stacked is reduced. To this end, the central computer may collect messages from the various interrogators and infer therefrom the wear profile, since the spatial profile of the waveguide is known.

Interrogator

The input end of the electrical conductor of the waveguide is electrically connected to an interrogator 18 or "reflectometer". The interrogator is configured to:

injecting an interrogation signal by generating a change in the potential difference between two conductors of the waveguide, and

-Analysing a response signal reflected in response to the interrogation signal.

Interrogator 18 generally includes transceiver 21 and control module 31 (fig. 2). The control module 31 typically comprises a processor and a memory into which a computer program is loaded. By means of the computer program, the processor is able to control the emission of the interrogation signal and to analyze the received reflected signal to identify echoes reflected by discontinuities. In one embodiment, the analysis is performed by an analysis computer 39 in communication with the interrogator.

The interrogator may be, for example, a voltage generator coupled to an oscilloscope, allowing the reflected signal to be received and analyzed. The interrogator may be a network analyzer equipped with software such as "VNA software" for generating an interrogation signal and analyzing the reflected signal.

In a preferred embodiment, as shown in FIG. 4, the first interrogator 18 ₁ is connected to the input end of the waveguide. The second interrogator 18 ₂ is connected to the output of the waveguide.

Thus, the second interrogator receives the portion of the interrogation signal injected by the first interrogator that is not reflected by the respective discontinuity of the waveguide. Preferably, the second interrogator may also transmit an interrogation signal. The presence of two interrogators advantageously makes it possible to obtain information about each side of the fracture zone in the event of a waveguide fracture. Thus, this improves the robustness of the device.

Analysis

The analysis by the interrogator is based on electrical time domain reflectometry (E-TDR) or electrical frequency domain reflectometry (E-FDR), which are conventional techniques for measuring changes in the state of a medium by a waveguide and interrogator.

Each interrogation signal, preferably in the form of a pulse or "Dirac", is formed by generating a change in the potential difference between two conductors of the waveguide. The latter returns a response signal which is then analyzed to derive therefrom information about the medium through which the pulse passes. In the event that there is an impedance discontinuity, for example, a significant physicochemical change in the medium results in a local impedance change, a portion of the interrogation signal is reflected back to the interrogator, which allows the change to be identified and analyzed.

The interrogation signal may take the form of any form of periodic wave. The interrogation signal may be repeated. Preferably, the maximum amplitude of the interrogation signal is between 0.1V and 100V V, and preferably less than 10V, and preferably less than 1V. The frequency of the highest peak in the frequency spectrum of the interrogation signal is preferably greater than 10kHz, preferably greater than 100kHz, preferably greater than 1MHz, preferably greater than 100MHz, preferably greater than 200MHz, preferably greater than 500 MHz, preferably greater than 1GHz, and/or less than 50GHz, preferably less than 30GHz, preferably less than 20GHz, preferably less than 10GHz, preferably less than 6GHz, preferably less than 4GHz. The interrogation signal may be transmitted in the form of a signal train, which preferably comprises a series of periodic signals, the frequency of which varies in accordance with the periodic signal in question.

The frequency of the interrogation signal is typically tailored to the length of the measurement component. The wavelength of the interrogation signal is typically shorter than the length of the measurement component of the waveguide. The ratio of the wavelength of the interrogation signal to the length of the measurement part of the waveguide is preferably 0.1 to 0.9, preferably 0.1 to 0.5, and preferably 0.1 to 0.3.

Preferably, the length of the measurement component of the waveguide is not a multiple of the wavelength of the interrogation signal to avoid resonance problems.

For example, for measurements at 600 ℃ or higher, the frequency of the interrogation signal may be 1GHz (corresponding to a wavelength of about 20 cm) for a length of the measurement component of the waveguide between 10m and 15 m.

Each interrogation signal propagates through the waveguide to the free end of the conductor. At each discontinuity, a portion of the interrogation signal, the "echo," is reflected back to the interrogator. All reflected echoes together form a response signal associated with the interrogation signal, which is analyzed by the interrogator.

In particular, the transmitted echo reflected by the input end of the waveguide, the terminal echo reflected by the output end of the waveguide, and the set of discontinuity echoes reflected by the discontinuity of the waveguide are different from each other. The discontinuity echoes are low in amplitude and have various amplitudes and shapes.

The interrogator is programmed to analyze the reflected signals and possibly compare them to determine information about the state of the object in the region of the measuring part of the waveguide and preferably to transmit a message accordingly.

Any technique for analyzing the response signal used in the electrical time-domain or frequency-domain reflectometry may be implemented, and in particular the technique described in article "Distributed temperature sensing with unmodified coaxial cable based on random reflections in TDR Signal" of Baokai Chen et al 2019 Meas sci. Technology 30.015105 or indeed article "ELECTRIC TIME domain reflectometry distributed flow sensor" of Aurimas Dominauskas et al in journal Composites Part A38 (2007) 138-146.

Preferably, the message comprises:

Values of the physical state of the object, in particular of the residual thickness or of the average temperature and/or of the temperature deviation along the measuring part, and/or

-A value of a change of said value from a previous situation, and/or

-A location of a defect or damage affecting said physical state of the object.

The message may be sent to a central computer and/or presented to the operator, for example on a screen and/or by turning on a light and/or by sending an audible signal.

In a preferred embodiment, at least a portion of the waveguide is capable of transmitting in its returned response signal a quantitative indication of the temperature it experiences due to wear of the object. As the thickness of the object portion, such as the bottom of the furnace, decreases, the frequency of the response signal returned by the waveguide changes. Such a change advantageously makes it possible to determine a local temperature change. Advantageously, it is thus possible in particular to detect abnormal changes in the temperature of the waveguide and to intervene to repair the object, for example to replace the refractory lining.

Object(s)

The object 30 may be all or part of a glassmaking furnace including a hot face, in particular a side wall or bottom of a furnace, or a brick or a set of bricks belonging to a side wall or bottom of a furnace. The object may also be, for example, a brick of a feeder, an upper structural part (gap brick, top brick, etc.), a forming part (lip, etc.), or a throat brick.

The object may comprise a backing layer and be, for example, a side wall or a bottom of the furnace.

The use of waveguides advantageously allows exposure to high temperatures, for example above 100 ℃, above 125 ℃, above 200 ℃ or above 300 ℃. For example, a metal waveguide cladding with a sacrificial polymer cladding allows for monitoring in an environment up to 300 ℃.

Manufacture or installation

The waveguides can be mounted using various techniques, in particular in the back layer of the object. Preferably, the waveguide is placed in a hot zone of the furnace at a temperature above 400 ℃, preferably above 500 ℃, preferably above 600 ℃, and below 1300 ℃, preferably below 1200 ℃, more preferably below 1100 ℃.

According to a preferred embodiment, at least a part, and preferably all, of the measuring component of each waveguide is covered by a sacrificial coating.

Each measuring component is arranged in an aperture (which is for example formed in the backing layer) or for example in a recess formed in the backing layer. A refractory starting material mixture, preferably concrete, having substantially the same composition as the backing layer is deposited in the aperture or recess to cover the sacrificial cladding of the waveguide.

The initial raw material is then solidified, preferably sintered, preferably during the furnace temperature increase. The sacrificial coating is typically removed by heat treatment, preferably during sintering or elevated temperatures, preferably by applying a temperature between 400 ℃ and 1200 ℃.

In addition to or as an alternative to the sacrificial coating, a sacrificial filler material (e.g., resin) may be used to fill the remainder of the apertures or grooves.

This method advantageously allows for close contact between the waveguide and the object, which enables good heat exchange and limits the risk of immersion of the molten glass while limiting the stress applied to the waveguide.

First embodiment furnace bottom

The object may be the bottom of a furnace according to the invention.

In the embodiment shown in fig. 4, the bottom has a substantially rectangular shape as seen from above.

As shown in FIG. 5, the bottom generally includes a first layer of refractory bricks 241 stacked in the form of plates in contact with molten glass, two concrete layers 242a and 242b, and two insulating layers 243a and 243b. All of these layers are laterally defined by bricks 244 (referred to as "kerb" bricks) and rest on a foundation 245.

Arrow D indicates the flow direction of the molten glass.

The refractory bricks 241 may have various shapes, such as a rectangular parallelepiped shape.

Refractory block 241 is preferably made of a material that is resistant to contact with glass at temperatures above 600 ℃, or even above 1000 ℃, or indeed above 1200 ℃. More than 90% by weight of the refractory brick may be composed of one or more oxides selected from the group consisting of ZrO ₂、Al₂O₃、SiO₂、Cr₂O₃、Y₂O₃ and CeO ₂. The refractory brick preferably contains more than 90% ZrO ₂、Al₂O₃ and SiO ₂.

In one embodiment, the brick contains more than 15% ZrO ₂, preferably 26% to 95% ZrO ₂. More than 90%, preferably more than 95% of the refractory brick composition generally consists of 26 to 40% ZrO ₂, 40 to 60% Al ₂O₃, and 5 to 35% SiO ₂. The glassy phase comprises about 5% to 50%, and preferably 10% to 40%. Preferably, the glass phase is a silicate-based phase, wherein the weight proportion of Na ₂ O is less than 20%, preferably less than 10%, and/or wherein the weight proportion of Al ₂O₃ is less than 30%. All percentages are generally given by weight of the oxide. Preferably, the oxides comprise more than 90%, preferably more than 95%, and preferably more than 98% of the weight of the refractory brick.

Concrete layers 242a and 242b are for example from the ERSOL series sold by SEFPRO corporation. They are typically formed by casting in a checker brick pattern arranged offset with respect to the pattern of the first upper layer (the layer closest to the glass) to increase the thermo-mechanical resistance and reduce the risk of immersion in the molten glass when penetrating.

Upper insulation 243a may be formed from precast refractory concrete pavement (typically from ERMOLD series supplied by SEFPRO).

The lower insulation layer 243b may be made of a fibrous insulation.

In a first configuration, shown in fig. 6, the waveguides 12 are arranged perpendicular to the flow direction D of the molten glass, each waveguide 12 being preferably surrounded by a sacrificial coating made of a polymer (e.g. PET or PE). The waveguide is placed on the upper insulating layer 243 a. The waveguides may optionally be held in place using a temporary adhesive that may decompose during the temperature rise of the furnace. Concrete forming the lower insulating layer 242b is poured onto and over the waveguides.

The waveguide is exposed to the exterior of the furnace through an aperture, for example formed through a kerb brick.

In one embodiment, the alumina protective coating 27 at least partially surrounds the at least one waveguide to protect the at least one waveguide and facilitate replacement thereof.

The waveguides 12 are connected to at least one interrogator 18, the interrogator 18 being electrically connected to the input end 12e of each waveguide via the transmission means 15, the interrogator 18 being configured to inject an interrogation signal through said end and to receive a response signal through the waveguide in response to said injection. The interrogator communicates with the analysis computer 39, for example by Wi-Fi or by cable. The analysis computer 39 preferably has memory and runs software or a program configured to correlate the response signals received from the waveguides with the state of the object.

In a possible second configuration (the layout of which is schematically shown in fig. 7 and which may be combined with the schematic illustration in the previous figures), the waveguide 12, preferably the waveguide 12 surrounded by a sacrificial polymer coating, is arranged parallel to the flow direction D of the molten glass. Waveguide 12 is placed on upper insulating layer 243 a. Alternatively, the waveguide 12 may be held in place using a temporary adhesive that may decompose during the furnace temperature rise. Concrete forming layer 242b is poured over and covering the waveguides.

Preferably, an array of waveguides is arranged in the bottom, preferably in the form of a plurality of parallel and/or perpendicular waveguides, for example in the form of two assemblies, the measuring parts of which are oriented at right angles when seen from above, as shown in fig. 3.

The waveguides are placed in a hot zone at the bottom, typically at a temperature of 800 to 1100 ℃.

In one embodiment, all waveguides lie in the same plane. Alternatively, the waveguides may be arranged at various depths in the bottom.

Example roof

The above definition is applicable to the top.

As shown in fig. 8, the roof includes dense bricks 241 forming abutments 241-1 and arches 241-2 of the roof 28, which are typically covered with a backing layer of concrete barrier 242 and insulation 243. According to one possible embodiment, the measuring means are preferably placed on the cold face of the dense brick 241 in the concrete barrier 242.

Example side wall of furnace

The above provisions may also be applied when the object is all or part of the side wall of the furnace.

As shown in fig. 10, the side walls of the furnace include dense bricks 241 in contact with the molten glass, and optionally a backing layer formed of porous refractory bricks. The waveguide 12, in particular at least the measuring part of the waveguide, may be fixed to a plate-like carrier 40 (see fig. 10), the plate-like carrier 40 itself being in contact with the brick 241. As mentioned above, the carrier is preferably made at least in part of a ceramic matrix composite.

As should now be clear, the present invention provides a solution that allows to evaluate the residual thickness or temperature of the object of a glass manufacturing furnace more accurately and in real time.

Of course, the invention is not limited to the embodiments described and shown, which are provided for illustrative purposes only.

In particular, the examples of objects described above are not exclusive.

Claims

1. A glass manufacturing furnace comprising:

-a glass melting chamber (11; 16) having a hot face (37) exposed to the interior of the chamber;

-a device for monitoring the state of a component of the furnace, called "object" (30), by means of an electrical time-domain or frequency-domain reflectometry, said device comprising:

an array of at least one filament-like waveguide, preferably a plurality of filament-like electromagnetic waveguides (12), each comprising a first and a second electrical conductor (12 ₁,12₂) electrically isolated from each other between an input end and an output end,

An interrogator (18) electrically connected to the input (12 e) and configured to inject an interrogation signal through the input, to receive a response signal reflected by the waveguide in response to the injection, to analyze the response signal and to send a message regarding the status of the object according to the analysis,

The waveguide comprising a measuring member (14) located between the input end and the output end of the waveguide, the measuring member (14) extending parallel to the hot face (37) and being located at a depth of more than 10cm,

The measuring means (14) comprises a plurality of discontinuities randomly distributed along at least the measuring means of the waveguide, said discontinuities being referred to as "basic discontinuities" (24),

The number of basic discontinuities per meter of measurement member of the waveguide is greater than 10,

The base discontinuity:

-being able to generate, in response to the injection of the interrogation signal, echoes having an amplitude greater than 0.5%, preferably greater than 1%, of the amplitude of the terminal echo reflected by the output end of the waveguide, these echoes being referred to as "fundamental secondary echoes", and/or

-Is formed by:

-Embossments produced by irregular segments of dielectric material interposed between said first and second electrical conductors, and/or

-A change in structure and/or composition of the environment around or between the first and second electrical conductors.

2. Furnace according to the previous claim, wherein the basic discontinuities are:

-A local variation of the distance between the first and second electrical conductors.

3. The furnace according to any of the preceding claims, wherein the embossment has a height of greater than 0.05mm, preferably greater than 0.1mm, preferably greater than 0.2mm, preferably greater than 0.4mm, preferably greater than 0.5mm, or even greater than 0.8mm, and less than 3mm, less than 2mm, or less than 1mm.

4. Furnace according to any one of the preceding claims, comprising a pad (23) in the form of a pad bead and made of a dielectric material, which is threaded on the first electrical conductor and/or on the second electrical conductor in the measuring part.

5. Furnace according to the previous claim, wherein a plurality of said plurality of pads are arranged together to form a segmented protective coating (27) extending over the entire length of the measuring part of the waveguide.

6. Furnace according to any one of the two preceding claims, wherein the length of the mat is less than 10cm, preferably less than 5cm, preferably less than 3cm, more preferably less than 2cm, and more than 0.5cm.

7. The furnace as claimed in any one of the preceding claims, wherein the waveguide fulfils the condition of rayleigh scattering.

8. The furnace as claimed in any one of the preceding claims, wherein:

a) The measurement component of each of the waveguides of the array extends parallel to the hot face and at a distance such that, in use, the measurement component is at a temperature of greater than 500 ℃;

b) The maximum distance between two of the measurement components of any two of the waveguides of the array is greater than 20cm;

c) Each of the waveguides of the array is plugged in an aperture in the object, the apertures configured to provide space for thermal expansion of the waveguides;

d) The equivalent diameter of the measurement component of each of the waveguides of the array is greater than 1mm and less than 50mm;

e) The first and second electrical conductors of the measurement component of each of the waveguides of the array are separated by a distance greater than 0.3mm and less than 30 mm;

f) The measuring member has the following number of bends:

-if the length of the measuring member is greater than or equal to 3 meters, there are less than 1 bend per meter.

9. Furnace according to any one of the preceding claims, wherein the array of waveguides is located at least partially, preferably entirely, within a backing layer or in a sub-layer of the backing layer, the backing layer being located behind a first layer formed by an assembly of bricks defining the hot face of the object.

10. The furnace as claimed in any one of the above claims wherein the radius of curvature of the measurement component of each of the waveguides of the array is at least 3 times greater than the equivalent diameter of the measurement component at each point.

11. The furnace as claimed in any one of the preceding claims, wherein:

The material from which the electrical conductor is made is a refractory or noble metal, preferably selected from the group consisting of platinum, tungsten, gold, palladium, rhodium, ruthenium, iridium or alloys of these elements, and/or

The first and second electrical conductors are separated by a dielectric material comprising an oxide of at least one element selected from Al, zr, mg, ca, ti and Si, and/or

-At least a portion of the measurement component of each of the waveguides of the array is protected by a ceramic cladding surrounding the measurement component.

12. The furnace as claimed in any one of the above claims wherein the measurement components of at least some of the waveguides are parallel to each other except for the bends.

13. The furnace as claimed in any one of the preceding claims, wherein each measurement component of the array of waveguides extends into a housing formed in the object and defining a space for thermal expansion of the waveguides, the ratio of the equivalent diameter of the housing to the equivalent diameter of the measurement component being greater than 1.05 and less than 3, the equivalent diameter of the measurement component or housing being the largest of the cross-sectional diameters of the measurement component or housing, respectively, taking into account all cross-sections along the measurement component or housing.

14. Furnace according to any one of the preceding claims, wherein the first and second conductors are fixed to the carrier (40), the carrier (40) preferably being in the form of a plate, being made of a ceramic matrix composite, and the first and second conductors being integrated into the carrier (40) or the first and second conductors being fixed to the surface of the carrier (40).

15. Furnace according to any one of the preceding claims, wherein at least one measuring part of one waveguide extends in a direction perpendicular to the flow direction of the molten glass.

16. The furnace as claimed in any one of the above claims wherein the measurement component of the waveguide is located at a depth of less than 200cm measured from the hot face.

17. A furnace according to any preceding claim, wherein the measurement component of each waveguide of the array is located at a distance such that in use the measurement component is at a temperature of greater than 700 ℃ and less than 1300 ℃.

18. The furnace as claimed in any one of the preceding claims, wherein the first and second conductors:

-to the carrier (40), the carrier (40) being formed of a ceramic matrix composite, preferably in the form of a plate, preferably by an interface layer or by refractory filaments, nails or tape, or

Integrated into the ceramic matrix composite, preferably in the form of a plate.

19. The furnace as claimed in any one of the above claims, wherein the magnitude of the fundamental secondary echo is less than 30% of the magnitude of the terminal echo reflected by the output end of the waveguide.

20. A method for manufacturing a furnace according to any one of the preceding claims, comprising, for at least one waveguide of the array, the following successive steps:

1) Inserting a sacrificial material between the measurement component of the waveguide and the object or precursor of the object, then

2) In the case where the sacrificial material has been inserted into a precursor of the object, the sacrificial material is removed after or while the object is manufactured to create a space for thermal expansion of the measurement component.

21. The method according to the preceding claim, wherein:

-the sacrificial material is a material covering a sacrificial coating of the measuring component, and for inserting the sacrificial material:

-making the object around the measuring part, or

-Forming a shell in the form of a recess or hole in the object or in a precursor of the object, then inserting the measuring part into the shell, then filling the shell with an unshaped refractory product, preferably a refractory concrete, comprising a binder, preferably cement, and being able to be cured by activation of the binder, then curing the unshaped refractory product, or

-The sacrificial material is a filler material independent of the waveguide, and for inserting the sacrificial material:

-forming a shell in the form of a recess or hole in the object or a precursor of the object, then inserting the measuring part into the shell, then filling the shell with the filling material in an amount such that the expansion space is formed, then filling the remaining part of the shell with an unshaped refractory product, preferably refractory concrete, comprising a binder, preferably cement, and being able to be cured by activation of the binder, then curing the unshaped refractory product.

22. The method according to any one of the two preceding claims, wherein:

-in step 2), during the temperature increase of the furnace and/or during the sintering of the unshaped refractory product or the object precursor, removing the sacrificial material by heating at a temperature of 400 ℃ to 1200 ℃.

23. A method for monitoring the condition of an object of a glass manufacturing furnace according to any of claims 1 to 19, the method comprising the steps of:

a. Manufacturing the glass manufacturing furnace;

b. For each waveguide, controlling the interrogator connected to the waveguide such that the interrogator injects an interrogation signal through the input end of the waveguide;

c. The response signal is analyzed to determine information about the state of the object in the region of the measurement component of the waveguide.

24. The method according to the preceding claim, wherein the information about the state of the object is the remaining thickness of refractory material or the temperature at one or more points on the object.