Patent Description:
Receptacles such as a ladle and an EAF include a refractory lining acting as a protection against high temperatures when the receptacle contains molten steel. However, the refractory lining is subject to wear or deposits coming from the molten steel.

Controlling the refractory lining plays an important role in order to achieve continuous and safe operation of the receptacle. Performing a visual check of the receptacle, when empty, has been the most common way to control the condition of the refractory lining and how it evolves.

However, this method has proven somewhat difficult, due to the environment of the receptacle in terms of dust and temperature, and non quantitative.

In order to make the control quantitative, <CIT> discloses using a laser scanner having a laser beam emitter, a mirror for deflecting the laser beam, and a laser beam receiver for receiving a laser beam reflected by the surface of the refractory lining. The transit time between emission and reception of the laser beam by the laser scanner provides a distance between the refractory lining and the laser scanner in the direction of the emitted laser beam. This provides the position of one point of the surface of the refractory lining with respect to the laser scanner.

Rotating the mirror about a first rotation axis and the laser scanner itself about a second rotation axis allows scanning the refractory lining in two mutually perpendicular directions, so as to obtain a plurality of points representing the scanned surface. This will be referred to as a "3D image" of the surface. By comparing successive images of the surface, it is possible to determine which parts of the refractory lining have worn off, or grown due to deposits, as the laser scanner is quite accurate.

However, due to the shape of the receptacle, internal geometrical constraints of the receptacle, and the fact that the laser scanner cannot be too close to a receptacle that is still hot, the laser scanner usually does not allow obtaining a full view of the surface of interest. For example, during use of a ladle, a slag rim tends to form along the opening of the ladle. This slag rim creates a shadow zone which hides areas of the interior surface of the ladle located directly beneath it to a scanner scanning the interior of the ladle from above.

In order to overcome this issue, the laser scanner is successively moved in different locations, from where it provides several 3D images. These 3D images are then merged into a global "image". Merging the successive 3D images requires very accurate knowledge of the successive locations of the laser scanner. This makes the whole process complex and the global image not so accurate, especially for a differential analysis over time such as wear control.

<CIT> discloses an inner wall surface profile observation apparatus for a coke oven chamber.

<CIT> discloses a method for positioning a measuring device emitting and receiving optical radiation for measuring wear in the lining of a container.

An aim of the invention is to provide a process for measuring wear of the refractory lining in a more accurate way.

To this end, the invention proposes a process according to claim <NUM>.

In other embodiments, the process comprises one or several of the feature(s), taken in isolation or any technical feasible combination according to claims <NUM> to <NUM>.

Other features and advantages of the invention will appear upon reading the following description, given by way of example and with reference to the accompanying drawings, in which:.

A process according to the invention will now be described with reference to <FIG>.

The objective is to measure wear of a refractory lining <NUM> of a receptacle <NUM> shown in <FIG> and <FIG>. The receptacle <NUM> is for example a ladle intended to contain molten metal. As a variant, the receptacle <NUM> is an EAF (shown in <FIG>) or a converter (not shown).

The refractory lining <NUM> is adapted to protect the receptacle <NUM> from high temperatures of the molten metal. After emptying the receptacle <NUM>, a deposit <NUM> (<FIG>) may be left, for example where the free surface of the molten metal was when the receptacle was filled.

The process comprises scanning a first surface 4A of the refractory lining <NUM> using a first laser scanner 21A in order to obtain a first initial set of data 5A (<FIG>) representative of the first surface of the refractory lining, and scanning a second surface 4B of the refractory lining using a second laser scanner 21B, distinct from the first laser scanner, in order to obtain a second initial set of data 5B (<FIG>) representative of the second surface of the refractory lining.

The second surface 4B includes a grey zone 6B for the first laser scanner 21A, as the deposit <NUM> forms an obstacle located between the first laser scanner and the grey zone 6B during scanning by the first laser scanner. In the shown example, similarly, the first surface 4A includes a grey zone 6A for the second laser scanner 21B, as the deposit <NUM> also forms an obstacle located between the second laser scanner and the grey zone 6A during scanning by the second laser scanner.

The process also comprises calculating a final set of data <NUM> using the first initial set of data 5A and the second initial set of data 5B. The final set of data <NUM> is representative of a surface <NUM> of the refractory lining <NUM> including the first surface 4A and the second surface 4B. The surface <NUM> is for example the sum of the first surface 4A and the second surface 4B.

The initial set of data 5A is a 3D (three dimensional) image of the first surface 4A in which the grey zone 6A is not visible (not present), and the second initial set of data 5B is a 3D image of the second surface 4B in which the grey zone 6B is not visible.

Using at least two laser scanners and merging their measurements makes is possible to obtain the final set of data <NUM> that is a 3D image of the whole surface <NUM>, as the second laser scanner 21B has a different view angle on the refractory lining <NUM> than the first laser scanner 21A.

The final set of data <NUM> provides information allowing to measure wear of the refractory lining <NUM>. The final set of data <NUM> is for example compared with a reference set, such as a previous 3D image representative of the surface <NUM>. Comparison enables to detect zones where the surface <NUM> has worn-off, and zones where deposits have occurred.

Moreover, the part of the surface <NUM> which does not belong to the grey zones 6A and 6B is scanned at least twice, which allows either improving the resolution of the final set of data <NUM>, or obtaining the final set of data more rapidly than with a single laser scanner.

Scanning of the first surface 4A and scanning of the second surface 4B are advantageously simultaneous, which allows saving time and reducing the duration of the exposure of the laser scanners 21A, 21B to a hot and dusty environment.

The process may comprise fixing bases <NUM> of the first laser scanner 21A and the second laser scanner 21B (<FIG> and <FIG>) on a support frame <NUM>, the bases being fixedly spaced apart along a transverse direction T of the support frame, and keeping the support frame in a same fixed position with respect to the receptacle <NUM> during scanning of the first surface 4A and the second surface 4B. By doing so, the relative position of the second laser scanner 21B with respect to the first laser scanner 21A is known and predetermined.

According to other particular embodiments (not shown), other techniques for keeping the first laser scanner 21A and the second laser scanner 21B in fixed positions relative to the receptacle <NUM> may be used. For example, the first laser scanner 21A and the second laser scanner 21B may be mounted on separate support frames.

Scanning of the first surface 4A and of the second surface 4B is advantageously performed in the same manner, so the first one will be explained in detail hereafter.

Scanning of the first surface 4A for example comprises emitting a laser beam <NUM> (<FIG>) using a laser beam emitter E (<FIG>), receiving a reflected laser beam <NUM> from the refractory lining <NUM> using a laser beam receiver R, measuring a transit time between emission of the laser beam and reception of the reflected laser beam, and deflecting the emitted laser beam in two mutually perpendicular directions A, B.

Deflecting the emitted laser beam <NUM> may be performed by rotating a mirror M (<FIG>) about a first rotation axis A with respect to the laser beam emitter E, and rotating the laser beam emitter about a second rotation axis B with respect to the base <NUM>.

Calculating the final set of data <NUM> is for example performed using parameters representative of a position of the base <NUM> of the second laser scanner 21B with respect to the base <NUM> of the first laser scanner 21A. Said parameters are used to perform one or several change(s) of coordinates so enabling to add up the first initial set of data 5A and the second initial set of data 5B expressed in a same coordinate system in order to obtain the final set of data <NUM>.

According to another embodiment, calculating the final set of data <NUM> includes detecting at least three points P1, P2, P3 (<FIG>) within the first initial set of data 5A and three points P1', P2', P3' within the second initial set of data 5B. The three points P1, P2, P3 and the three points P1', P2', P3' are representative of three landmarks L1, L2, L3 located within or around the first surface 4A and the second surface 4B.

The final set of data <NUM> is calculated so that the three points P1, P2, P3 and P1', P2', P3' are superposed as shown in <FIG>.

With reference to <FIG> and <FIG>, an installation <NUM> is described.

The installation <NUM> comprises the receptacle <NUM>, a device <NUM> for measuring wear of the refractory lining, and a floor <NUM> on which the device stands.

The receptacle <NUM> is for example a steel ladle intended to contain molten steel, for example coming from an electric arc furnace (not represented). The ladle is approximately symmetrical around a vertical direction V. The ladle defines a volume <NUM> for receiving molten steel, and for example has the deposit <NUM> around its mouth.

The device <NUM> comprises a box <NUM>, the two laser scanners 21A, 21B located within the box, a base <NUM>, and an arm <NUM> holding the box and protruding from the base along a longitudinal direction L approximately horizontal.

The box <NUM> is located above the ladle in this example in this example.

The base <NUM> is advantageously adapted to roll on the ground <NUM>.

The base <NUM> includes a computer <NUM>, optionally a control unit <NUM> with one or several control screens, a source of compressed air <NUM>, and a power source <NUM>. The base <NUM> is advantageously equipped with one or several cooling fans (not shown) having dust filters (not shown).

As a variant, the control unit <NUM> is replaced by a remote control unit (not shown).

The base <NUM> and the arm <NUM> are advantageously covered with a protective mat (not shown), notably on sides facing the receptacle <NUM>. For example the mat comprises an aluminised glass fabric or any insulating material.

The power source <NUM> advantageously allows the device <NUM> to be autonomous in terms of power supply. The power source <NUM> is for example an inverter.

According to a variant, the power source <NUM> is replaced by a connexion to an electricity grid (not shown).

The source of compressed air <NUM> is for example a cylinder.

The computer <NUM> is suitable for monitoring the laser scanners 21A, 21B. Advantageously, the computer <NUM> includes one or several dedicated software(s) for analysing the measurements performed by the laser scanners 21A, 21B and for producing the final set of data <NUM>.

As a variant (not shown), the computer <NUM> is remote from the base <NUM>.

With reference to <FIG> and <FIG>, the box <NUM> has a front face <NUM> facing the opening of the ladle downwards. The box <NUM> also comprises a main part <NUM> fixed to the arm <NUM>, and a closing system <NUM> movable with respect to the main part between a closed position, wherein the box is closed around the laser scanners 21A, 21B, and an open position (<FIG> and <FIG>), wherein the main part <NUM> defines at least one opening <NUM> in the front face <NUM>.

In a particular embodiment, the box <NUM> is rotatably mounted on the base <NUM> around the longitudinal direction L.

When the closing system <NUM> is in the closed position, the interior of the box <NUM> is protected against dust, and from water projections from all directions.

The opening <NUM> extends along the longitudinal direction L and along the transverse direction T, which is perpendicular to the longitudinal direction and for example horizontal.

For example, the opening <NUM> has a planar, advantageously rectangular, shape. The opening <NUM> is advantageously parallel to the transverse direction T and for examples defines an angle α (<FIG>) with the longitudinal direction L ranging between <NUM>° and <NUM>°.

The closing system <NUM> comprises a cover <NUM> rotatably mounted on the main part <NUM> around an axis R (<FIG>), and for example one or two gas springs <NUM> adapted to hold the cover in the open position as shown in <FIG> and <FIG>.

The closing system <NUM> advantageously includes a seal (not shown) in fluoroelastomer installed between the cover <NUM> and the main part <NUM>. Fluoroelastomer is a fluorocarbon-based synthetic rubber able to withstand a range of temperatures from -<NUM> to <NUM>.

As a variant (not shown), the seal includes a coating adapted for conducting heat towards the rear of the device <NUM>, and for reflecting thermal radiations Δ from the receptacle <NUM>.

By "adapted to reflect thermal radiations from the receptacle", in the present application, it is meant that the laser scanners 21A, 21B are protected from the thermal radiations emitted by the receptacle <NUM>. The axis R is for example approximately parallel to the transverse direction T.

The cover <NUM> advantageously comprises an external protective panel <NUM> adapted to reflect thermal radiations Δ coming from the receptacle <NUM> when the closing system <NUM> is in the closed position.

In one embodiment, the cover <NUM> is adapted to be manually moved in order to move the closing system <NUM> from the closed position to the open position, and vice versa. To that end the cover <NUM> advantageously comprises handles <NUM> and fasteners <NUM>, for example hook clamps. In another embodiment the cover <NUM> is automatically controlled.

The protective panel <NUM> is for example made of reflective metal, such as stainless steel, polished stainless steel, aluminum or polished aluminum and may contain an insulating material such as ceramic fiber. The external protective panel <NUM> is advantageously spaced apart from the rest of the cover <NUM>, as best seen on <FIG>.

The main part <NUM> of the box <NUM> has a rear face <NUM> (<FIG>) opposite the front face <NUM> with respect to the receptacle <NUM>, advantageous having fins <NUM> directed outwardly in order to favor a thermal exchange between the box and the surrounding atmosphere.

In a particular embodiment, two fans <NUM> are fixed to the rear face <NUM> and adapted to blow or extract air on the fins <NUM> to increase cooling of the fins <NUM>.

The main part <NUM> also has a bottom wall <NUM>, for example substantially flat, and advantageously forming a connection interface for mechanically connecting the box <NUM> and the arm <NUM>. The main part <NUM> has an upper wall <NUM>.

The main part <NUM> comprises the support frame <NUM>, for example fixed to the bottom wall <NUM> towards the interior of the box <NUM>, and extending transversely.

The main part <NUM> advantageously includes two nozzles <NUM> (<FIG>) connected to the source of compressed air <NUM> for blowing compressed air respectively towards the laser scanners 21A, 21B.

The device <NUM> optionally includes an internal protective screen <NUM> adapted to reflect at least <NUM>% of the energy of the thermal radiations Δ coming from the receptacle <NUM> through the opening <NUM> of the front face <NUM>.

The internal protective screen <NUM> for example comprises several modules <NUM> distributed along the transverse direction T, and optionally a transverse module <NUM> adapted to protect the support frame <NUM> from the thermal radiations Δ.

The transverse module <NUM> is interposed between the support frame <NUM> and the receptacle <NUM>. The transverse module <NUM> extends transversely across the opening <NUM>.

Each module <NUM> is adapted to reflect at least <NUM>% of the energy of the thermal radiations Δ coming from the receptacle <NUM>.

The modules <NUM> are advantageously fixed to the lower wall <NUM> and the upper wall <NUM> of the main part <NUM>, so as to be easily movable by an operator (not shown) along the transverse direction T in order to define two scanning windows 86A, 86B respectively in front of the laser scanners 21A, 21B.

For example, each module <NUM> has an "L" shape along the transverse direction T. Each module <NUM> comprises two panels <NUM> forming the "L". One of the panels <NUM> is for example approximately perpendicular to the longitudinal direction L, and the other one is approximately perpendicular to the vertical direction V. The panels <NUM> are adapted to reflect thermal radiations Δ coming from the receptacle <NUM> substantially radially with respect to the transverse direction T through the opening <NUM>.

Advantageously, the modules <NUM> and the transverse module <NUM> comprise at least <NUM>% in weight of polished aluminum.

Several washers (not shown), for example those known as "Delrin washers", are interposed between the support frame <NUM> and the lower wall <NUM> in order to limit thermal conduction.

The laser scanners 21A, 21B are mounted on the support frame <NUM>. They are spaced apart along the transverse direction T.

The laser scanners 21A, 21B are for example Focus3D laser scanners commercially available from Faro, or similar ones. The laser scanners 21A, 21B are advantageously protected with reflective adhesive tape (not shown) stuck to their walls. The adhesive tape is advantageously in aluminised glass fabric, for example the one referenced <NUM> by the company <NUM>.

The laser scanners 21A, 21B are adapted to be monitored by the computer <NUM>.

They are advantageously analogous, so only the laser scanner 21A will be described in detail hereafter. The laser scanner 21B is equivalent to the laser scanner 21A translated along the transverse direction T.

The laser scanner 21A comprises the laser beam emitter E and the laser beam receiver R (<FIG>). The laser scanner 21A also comprises a time measurement system <NUM> to measure the transit time between emission of the laser beam <NUM> and reception of the reflected laser beam <NUM>, and a deflector <NUM> for deflecting the laser beam <NUM> in the two mutually perpendicular directions A, B.

The deflector <NUM> includes the mirror M which is rotatable about the first rotation axis A with respect to the laser beam emitter E, and a unit <NUM> configured to rotate the laser beam emitter E about the second rotation axis B with respect to the support frame <NUM>.

The unit <NUM> comprises the base <NUM> mounted on the support frame <NUM>, and a rotary part <NUM> rigidly fixed to the laser beam emitter E and the laser beam receiver R.

The rotary part <NUM> rotates about the second rotation axis B and makes the laser beam emitter E, the laser beam receiver R and the mirror M rotate about the second axis B.

The second axis B is for example perpendicular to the transverse direction T and advantageously horizontal in the example. The second axis B of the first laser scanner 21B is parallel to the second axis B of the second laser scanner 21B, and separated by a distance D which is fixed during scanning.

The first axis A is perpendicular to the second axis B and rotates about the second axis B with respect to the support frame <NUM>. When the laser scanners 21A, 21B are idle, the first axis A is for example parallel to the transverse direction T.

The arm <NUM> is configured so that the laser scanners 21A, 21B are off-centred (<FIG>) along the transverse direction T with respect to the ladle symmetry axis.

According to a particular embodiment, the length of the arm <NUM> is adjustable.

Advantageously, the arm <NUM> is rotatable with respect to the base <NUM> between a first position (<FIG>) in which the arm is approximately horizontal, and a second position (<FIG>) in which the arm is approximately vertical.

A way of using the installation <NUM> will now be described.

The ladle, previously emptied, and the device <NUM> are brought into the relative position shown in <FIG> and <FIG>. For example, the device <NUM> occupies a fixed position on the floor <NUM> and the ladle is brought under the device, the ladle being in a vertical position.

When the laser 21A and 21B are idle, the closing system <NUM> is advantageously in the closed position, so as to be protected from dust and heat radiating from the ladle.

The optional heat protection systems, such as the internal protective screen <NUM>, the protective panel <NUM>, the structure of the rear face <NUM> and the fans <NUM>, and the compressed air blowing nozzles <NUM> further protect the laser scanners 21A, 21B.

In order to scan the refractory lining <NUM>, the closing system <NUM> is put in the open position.

The laser scanners 21A, 21B advantageously work simultaneously in order to reduce their exposure time to dust and heat. Scanning is performed as explained above.

When scanning is over, the closing system <NUM> is put in the closed position.

An installation <NUM> according to a variant will now be described with reference to <FIG>. The installation <NUM> is analogous to the installation <NUM> shown in <FIG>, and <FIG>. Similar elements bear the same numeral references. Only the differences will be described in detail.

In the installation <NUM>, the receptacle <NUM> is still for example a ladle, but in a different position. The ladle lies on its side, so that its symmetry axis is approximately horizontal. The arm <NUM> of the device extends along the vertical direction V.

For example, compared with the configuration shown in <FIG> and <FIG>, the arm <NUM> has been rotated around the transverse direction T with respect to the base <NUM>. The front face <NUM> of the box <NUM> faces the ladle horizontally in this example. This provides the device <NUM> with flexibility, as the device is suitable for scanning a receptacle from above or from aside.

The use and the advantages of the installation <NUM> are similar with those of the installation <NUM>.

An installation <NUM> according to another variant will now be described with reference to <FIG>. The installation <NUM> is analogous to the installation <NUM> shown in <FIG>. Similar elements bear the same numeral references. Only the differences will be described in detail.

The installation <NUM> comprises a receptacle <NUM> which is an electric arc furnace having a refractory lining <NUM>, and a door <NUM>.

The device <NUM> is in the same configuration as represented in <FIG> and <FIG>, with the arm <NUM> extending along the longitudinal direction L (horizontally), so that the box is located inside the furnace.

The use and the advantages of the installation <NUM> are similar with those of the installations <NUM> and <NUM>, with the following differences.

Prior to use, the device <NUM> is moved on the floor <NUM> in order to introduce the box <NUM> within the receptacle <NUM> via the door <NUM>. Then scanning is performed in the same way as previously described, with the same results and advantages.

In particular, the device <NUM> allows scanning zones that would be grey for the first laser scanner 21A.

In the graph show in <FIG>, a curve C1 is an example of a profile which was obtained from a final set of data provided by the device <NUM> after scanning the electric arc furnace shown in <FIG>. The profile is taken in a plane P which is perpendicular to the transverse direction T. Curve C1 represents a vertical profile of a lateral wall <NUM> of the receptacle <NUM>.

Claim 1:
Process for measuring wear of a refractory lining (<NUM>) of a receptacle (<NUM>; <NUM>) intended to contain molten metal, the process comprising the following steps:
- scanning a first surface (4A) of the refractory lining (<NUM>) using a first laser scanner (21A) in order to obtain a first initial set of data (5A) representative of the first surface (4A),
- scanning a second surface (4B) of the refractory lining (<NUM>) using a second laser scanner (21B), distinct from the first laser scanner (21A), in order to obtain a second initial set of data (5B) representative of the second surface (4B), wherein the second surface (4B) includes a grey zone (6B) for the first laser scanner (21A), a deposit (<NUM>) located on the receptacle (<NUM>; <NUM>) defining an obstacle (<NUM>) located between the first laser scanner (21A) and the grey zone (6B) during scanning by the first laser scanner (21A), and
- calculating a final set of data (<NUM>) using the first initial set of data (5A) and the second initial set of data (5B), the final set of data (<NUM>) being representative of a surface (<NUM>) of the refractory lining (<NUM>) including the first surface (4A) and the second surface (4B).