EP3097996B1 - Method for heating a brick-lined device - Google Patents

Description

The invention relates to a method for heating a bricked device according to the preamble of claim 1.

Heating the masonry of bricked-up facilities, e.g. Pans in the field of steel production are conventionally made taking into account a predetermined temperature curve, which is prescribed by the manufacturers of the lining. In practice, such predetermined temperature curves can be achieved by a suitable setting of the thermal output of a burner or by regulating the air ratio of the burner.

DE 199 35 451 A1 shows a pan preheating system and a pan preheating method in which the rate of heat input to the pan is calculated and monitored over the entire preheating period. Here, the variable average slope, which represents the change in the heat supply rate with the lapse of time, is calculated. Furthermore, the changing average slope is corrected with regard to unavoidable fluctuations in the measurements of the heat supply rate. Finally, the change in the variable average slope is calculated with the passage of time, on the basis of which the operational readiness of the pan is displayed if this variable average gradient falls below a setpoint criterion which indicates a completely preheated pan. The technology according to DE 199 35 451 A1 is used to provide an accurate indication of when a fireproof lining or lining of a pan is warmed up uniformly - and thus ready for use. However, specific parameters relating to the material of the lining of a pan are not taken into account.

WO 2008/154595 A2 discloses a method of heating pans for steel making. The temperature during the heating process is changed by controlling a burner of a heating unit based on measurements of the refractory material of the pan. In order to reduce heat losses and for efficient heating, the heating unit comprises a valve mechanism with which a flame size of the burner of the heating unit can be varied while the heating process is idling.

Out KR 20120009104 A a heating system for a ladle is known in which a temperature sensor is mounted in a ladle lid to measure the temperature inside the ladle. The signal from the temperature sensor, which indicates the temperature inside the ladle, is received by a controller. The controller then controls an energy source of the heating system so that the inside of the pan can be controlled by a preset temperature.

KR 20130075280 A discloses a ladle heating system comprising a lid, a burner, a photography device and an output member. The burner heats the inner surface of an interior of a pan by directing a flame into the interior. The photography device takes pictures of the inner surface of the interior of the pan in order to generate thermal images of the inner surface of the interior and thus to calculate the temperature of the inner surface of the interior. The output part outputs the thermal images and the surface temperature of the interior.

The above conventionally known methods for heating bricked-up devices, taking into account a predetermined temperature curve as explained above, are subject to the disadvantage that no local temperature gradients for the brick lining, in local or temporal terms, are taken into account for predetermined heating or temperature curves. In this respect, high safety areas must be provided for the heating curves in order to avoid damage to the brickwork in any case. These safety areas then lead disadvantageously to a relatively long heating-up time until a target temperature is reached for the lining.

Fig. 6 shows a diagram according to the prior art for a heating curve T _B , in connection with a temperature gradient that forms in the lining of a ladle when it is heated. This temperature gradient is formed between a surface of the lining and a section of the lining that is spaced, for example, 10 mm from the surface. When heating up, the greatest temperature gradients are to be expected on the inside of the lining. The diagram of Fig. 6 illustrates that on the one hand the heating curve T _B rises linearly and uniformly, and on the other hand the temperature gradient, as evidenced by the temperature curves with respect to the surface of the lining and a point which, as explained, is spaced about 10 mm from the surface, increases with increasing temperature of the energy source. The increase in this temperature gradient is due to the fact that the temperature increase within the lining (T _inside ) "lags behind" or only increases with a delay in comparison to the temperature increase at the surface of the lining (T _surface ). With such a temperature development within the lining, a desired shortening of heating times is either only possible to a limited extent or not at all.

Out RU 2493519 C2 A smelting boiler for iron ore is known in which the energy which is supplied to electrodes in contact with the iron ore to be smelted is adjusted or regulated taking into account the ratio of the heat flow which arises in one wall of the boiler to the total energy consumption. The voltage that is applied to the electrodes is regulated in such a way that there is neither an upper limit value nor a lower limit value for the ratio between the heat flow and the total energy. With regard to a prior heating of the boiler before the iron ore to be treated is introduced into it, see RU 2493519 C2 not specified.

The invention is accordingly based on the object of making the heating of a bricked-up device more efficient - namely with a shorter heating-up time until a predetermined target temperature is reached - and at the same time gentle on the material of the lining.

The above object is achieved by a method with the features of claim 1. Advantageous developments of the invention are defined in the dependent claims.

The method according to the present invention is used to heat a bricked-up device, in which the bricking is heated by an energy source. When the lining is heated up, a temperature gradient generated therein is recorded and used as a control variable for controlling the energy source. The energy source is controlled during the heating up of the lining until a predetermined target temperature of the lining is reached or as a function of a predetermined target value for a temperature gradient that forms within the lining or sets therein. The predetermined target value for this temperature gradient is determined taking into account at least one material characteristic value of the lining from its maximum permissible thermal stress σ _Tmax .

With regard to the temperature gradient formed within the lining and the corresponding predetermined target value, it should be pointed out that this is a local gradient, which is also referred to below as dT / dx.

The temperature gradient which is formed therein when the lining is heated can expediently be detected by a suitable sensor device, this temperature gradient then being used as a control variable for controlling the energy source.

The invention is based on the essential finding that the lining of a bricked-up device is heated with knowledge or taking into account at least one material property or material characteristic of the brick lining, namely the maximum permissible thermal stress of the object. With at least one such material characteristic value, the predetermined target value for the temperature gradient can be determined, which is to be observed for the heating of the brick lining and serves as the basis for the activation of the energy source. This makes it possible to maximize the amount of energy that is to be introduced into the material of the lining for heating it up. Because such a predetermined setpoint for the temperature gradient has been determined taking into account a maximum permissible thermal stress, the present invention reliably ensures that maximum permissible thermal stresses within the lining are not exceeded when the lining is heated. This ensures that the stone material of the brickwork is not damaged. In other words, knowing or taking into account a maximum permissible thermal stress for the material of the lining, in conjunction with a process control in which a maximum permissible thermal stress is not exceeded, advantageously leads to gentle material heating and to an increase in service life, e.g. for ladles or the like.

In addition, it is possible to use the heating curve to heat the lining depending on its thickness, e.g. of a radial thickness of the lining in a ladle or the like.

In an advantageous development of the invention, it can be provided that the predetermined setpoint for the temperature gradient is also determined taking into account the specific heat capacity c _p , the thermal conductivity (λ) and / or the density (p) of the lining.

The detection of a temperature gradient that forms within the lining provides information about a temporally and locally local thermal state of the lining. Based on this information, it is advantageously possible according to the present invention to regulate the energy source accordingly for heating the lining.

In an advantageous development of the invention, it can be provided that at least one sensor device for detecting the temperature gradient generated in the material of the lining is arranged within the lining. The energy source is then connected to such a sensor device in terms of measurement technology via a controlled system, the energy source being controlled as a function of the measured values of the sensor device and as a function of the predetermined target value for the temperature gradient. Such a type of sensor device arranged within the material of the lining advantageously enables the provision of precise information regarding the temporally and locally local thermal state of the lining, which then makes it possible to regulate the energy source appropriately for heating the object. This is particularly advantageous for determining the state of wear of a ladle, or for unknown material values of a ladle or its lining.

With regard to the sensor device mentioned above, it is expedient that it is also used to detect a temperature directly on a surface of the brick lining which is adjacent to the action of the energy source and, for example, is directly adjacent to a flame of a burner or the like. In this way, the sensor device can detect a temperature gradient for the lining, which is established when the lining is heated between a surface of the lining that adjoins the action of the energy source and an inner region of the object.

In an advantageous development of the invention, the energy source can be controlled in such a way that when the lining is heated, a temperature gradient generated therein assumes a constant value until the target temperature for the object is reached. This has the advantage that the heating is both gentle on the material and efficient, i.e. with a short heating-up time.

In an advantageous development of the invention, the energy source can be controlled in such a way that when the lining is heated up, a temperature gradient generated therein does not exceed the predetermined target value for the temperature gradient. This advantageously ensures that damage to the material of the lining is avoided in any case, in particular in that the maximum permissible thermal stresses for the lining are not exceeded.

In an advantageous further development of the invention, the energy source can be controlled such that when the lining is heated up, a temperature gradient generated therein is at least 80%, preferably at least 90%, further preferably at least 95% of the predetermined target value for the temperature gradient. This advantageously ensures that the amount of energy that is to be introduced into the material of the brickwork is maximized over time and the resulting heating-up time is reduced or minimized. In this way, the lining is supplied with exactly the amount of energy that its material "can still withstand" without being damaged. The fact that, as a result of the control or regulation of the energy source, the temperature gradient generated within the lining may not exactly correspond to 100% of the corresponding predetermined target value, but may be, for example, only 80%, 90% or at least 95% of this predetermined target value "Safety factor" can be understood to be on the safe side when heating up the lining.

It should be pointed out that the actual temperature gradient that is generated within the lining can either be constant or alternatively can have a time-variable value. It is possible here that the temperature gradient can have any change over time for the entire period of heating up the lining or for a sub-area of this period. Such a change in the temperature gradient over time is achieved by a suitable control of the energy source, the temperature gradient which is formed in the lining either being selected to be smaller than the corresponding predetermined setpoint value or, for a short time, also larger than this setpoint value. For example, it is possible for the actual temperature gradient within the lining to fluctuate in a range between 40% and 120% of the predetermined target value for the temperature gradient.

In an advantageous development of the invention, it can be provided that the control of the energy source for heating the lining takes place as a function of a database in which measured values relating to predetermined materials for the lining are stored. With regard to such a database, it may be pointed out that corresponding data relating to the material of a concrete brick lining are stored therein, these data having been determined, for example, in preliminary tests. If a control device for the energy source is connected to the database in terms of signal technology, it is possible to control the energy source in a suitable manner as a function of data stored in the database.

In addition to or as an alternative to controlling the energy source on the basis of data which have been determined by means of preliminary tests and correspondingly stored in the database, it is also possible to calculate the data for controlling the energy source simultaneously, namely on the basis of the data from the sensor device ( to determine a temperature gradient within the object) and / or the temperature sensor (to determine a temperature inside the object that is to be heated).

The method according to the present invention can be used in the field of steel production. In this case, the bricked-up device for which heating is provided or necessary may be, for example, an oven, a pan, a converter, a distributor or the like.

With regard to the energy source, it may be pointed out that this can be a burner with which a so-called ladle fire is generated for heating the lining, for example a ladle.

By means of a method according to the present invention, it is possible to considerably reduce the heating-up times required for a bricked-in device, while at the same time the lifespan of the brick lining is not reduced by such accelerated heating. As a result, process times in the field of steel production, for example, when the bricked-up device to be heated is a ladle or the like, can be considerably reduced. In the sense of the invention, the heating process for a bricked-up device is understood as a coordinated system of heat source and bricked-up device to be heated up, with the aim of achieving the fastest possible heating up to the predetermined target temperature, without - as already explained - the lifespan of the one to be heated up Brick lining is reduced.

In an advantageous development of the invention it can be provided that at least one temperature sensor is arranged in the interior of the bricked-in device, by means of which a temperature is measured within the interior of the bricked-in device when the lining is heated up and corresponding data is then sent to the database. This leads to the advantage that a direct effect of the energy source on the temperature of the interior is also taken into account for heating the lining.

Another advantage for the method according to the present invention is that it can be implemented with existing technical facilities. In other words, it is only necessary to implement the invention a suitable program-technical device in order - as explained - to control an energy source for heating the lining as a function of a predetermined target value for the temperature gradient generated within the lining.

• Brennstoffeinsparung,
• Erhöhung der Standzeit für die Ausmauerung einer ausgemauerten Einrichtung,
• erhöhte Prozessflexibilität im Bereich der Stahlerzeugung, durch eine Reduzierung der notwendigen Aufheizzeit für ausgemauerte Einrichtungen, Öfen, Pfannen, Konverter, Verteiler oder dergleichen, und
• Reduzierung der notwendigen Gesamtzahl von Pfannen wegen der soeben genannten höheren Prozessflexibilität.

Further advantages of the invention are based on:

• Fuel saving,
• Increasing the service life for the lining of a bricked-in facility,
• increased process flexibility in the field of steel production, by reducing the heating-up time required for bricked-up facilities, ovens, pans, converters, distributors or the like, and
• Reduction of the total number of pans required due to the higher process flexibility just mentioned.

In an advantageous development of the invention, there is the possibility of reacting appropriately to a change in the process situation. For example, the case may occur that the target time at which the lining of the bricked-in device is to reach the predetermined target temperature is shifted during the heating, e.g. by 30 minutes earlier or later. Accordingly, it is possible to control the energy source in a suitably modified manner, so that the heating process is then adapted to the changed target time and the lining of the bricked-out device only then reaches the predetermined or desired target temperature precisely at this changed target time. The temperature gradient that is formed within the lining can be varied over time, for example in order to reach the desired target temperature in a shorter time.

Fig. 1

eine vereinfachte Prinzipdarstellung von Komponenten, zur Durchführung eines erfindungsgemäßen Verfahrens,

Fig. 2

ein Diagramm für einen Temperaturgradienten, der sich beim Aufheizen einer ausgemauerten Einrichtung darin bei Durchführung eines erfindungsgemäßen Verfahrens einstellt,

Fig. 3

eine vereinfachte Prinzipdarstellung von Komponenten nach einer weiteren Ausführungsform der Erfindung, zur Durchführung eines erfindungsgemäßen Verfahrens,

Fig. 4

ein Diagramm zur Darstellung eines Aufheizverhaltens nach der vorliegenden Erfindung, im Vergleich zu Aufheizverhalten nach dem Stand der Technik, und

Fig. 5

ein Diagramm zur Erläuterung eines Temperaturgradienten, zur Durchführung eines Verfahrens nach der vorliegenden Erfindung.

An exemplary embodiment of the invention is described in more detail below with the aid of a schematically simplified drawing. Show it:

Fig. 1

a simplified basic illustration of components for carrying out a method according to the invention,

Fig. 2

2 shows a diagram for a temperature gradient which arises when a bricked-up device is heated up when a method according to the invention is carried out,

Fig. 3

a simplified schematic diagram of components according to a further embodiment of the invention, for performing a method according to the invention,

Fig. 4

a diagram showing a heating behavior according to the present invention, compared to heating behavior according to the prior art, and

Fig. 5

a diagram for explaining a temperature gradient, for performing a method according to the present invention.

Fig. 1 shows in principle greatly simplified components with which a method according to the present invention can be carried out. With "1" is a bricked-up device, which can be, for example, a ladle or the like. For the following explanation, the bricked-up device is always referred to as a ladle, without any limitation.

The ladle 1 comprises a lining 2, which can be heated to a target temperature in interaction with an energy source 4. The energy source 4 can be a burner. In the following description - and without any limitation - the energy source 4 is always referred to as a burner.

The lining 2 of the ladle 1 is heated in that a ladle fire 5 of the burner 4 is directed into an interior I of the ladle 1. In the representation of Fig. 1 A cover device, which can be connected to the burner 4 and closes the interior I of the ladle 1, is not shown for simplicity.

The burner 4 is connected to a control device 6. The meaning and the mode of operation of such a control device are explained in detail below.

At least one sensor device 8, a first sensor 8a and a second one, is arranged within the lining 2 of the ladle 1 Has sensor 8i. It can be provided here that the first sensor 8a is attached to a surface 3 of the lining 2, the second sensor 8i being arranged inside the lining 2 and thus spaced apart from the surface 3. In any case, it is possible by means of the sensor device 8 and its first sensor 8a and second sensor 8i to detect a temperature gradient within the lining 2, which is formed therein when the lining is heated.

Both the sensor device 8 and the burner 4 are connected to the control device 6 in terms of signal technology, namely by means of respective data connections 10 which are shown in FIG Fig. 1 are symbolically and simply indicated by dashed lines. These data connections 10 can be implemented, for example, by cable routes or by radio links.

The invention now works as follows:
To heat the ladle 1 and its brick lining 2 to a predetermined target temperature, the burner 4 is positioned adjacent to the interior I of the ladle 1 and appropriately controlled by the control device 6. The ladle fire 5 of the burner 4 is directed into the interior I of the ladle 1, as a result of which a surface 3 of the lining 2 is first heated and then this energy input successively acts into the lining 2 in order to achieve a uniformly high temperature within the entire lining 2 produce.

The control of the burner 4 by the control device 6 takes place as a function of a predetermined target value for a temperature gradient which forms within the lining during its heating process. This predetermined setpoint for the temperature gradient is formed taking into account at least one material characteristic of the lining maximum permissible thermal stress σ _Tmax determined.

For the control of the burner 4 by the control device 6, it is useful if for this purpose the signals from the sensor device 8, ie information for the temperature gradient that arises within the lining 2 when the burner 4 heats up, for the operation of the burner 4 Controlled variable is used. In this way it is possible to keep the temperature gradient generated within the lining 2 at a constant value. Such a constant temperature gradient is in principle simplified in the diagram of Fig. 2 represented, namely by the temperature curve Ta of the first sensor 8a (on the surface 3 of the lining 2) and the temperature curve Ti of the second sensor 8b (at a point within the lining 2, namely at a distance from its surface 3).

Fig. 3 shows a further embodiment for the present invention or for performing the method according to the invention. Compared to the representation of Fig. 1 a database DB is additionally provided, which is connected to the control device 6 for signaling purposes. Measured values relating to predetermined materials for the brick lining 2 of a specific ladle 1 can be stored in this database DB, which have been determined, for example, in preliminary tests. Correspondingly, the burner 4 can be suitably controlled or regulated by the control device 6 taking into account the entries in the database DB.

In addition, in the embodiment according to Fig. 3 it should be provided that a temperature sensor 12 is arranged in the interior I of the ladle 1, which is connected to the database DB for signaling purposes. Temperature signals that are detected by the temperature sensor 12 in relation to the interior I of the ladle 1 can thus be suitably sent to the database DB and stored therein. On the basis of this is then a Operation of the burner 4 is also possible taking into account the information that has been determined by means of the temperature sensor 12 for the interior I of the ladle 1.

By means of a method according to the present invention, it is possible to significantly shorten the heating-up time for, for example, a ladle 1 or the like, in order to achieve a predetermined target temperature for the lining 2 of the ladle 1 in a shorter time. Such a significant reduction in heating time based on the present invention compared to conventional heating times according to the prior art is symbolic in the diagram of FIG Fig. 4 indicated. A target temperature Z up to which a necessary heating is carried out is indicated by a horizontally running dotted line. Furthermore, in this diagram, a heating-up time which is achieved with the present invention is represented by a solid line. In comparison, heating times according to the prior art are shown both by a dashed line and by a dash-dotted line.

The diagram of Fig. 4 illustrates that it is possible with the method according to the present invention to at least halve or even further shorten heating times previously possible for ladles.

Possible curves for a temperature gradient dT / dx are shown in Fig. 5 shown, namely in the lower representation thereof. Different possible course curves for the temperature gradient are symbolized here in each case with a continuous full line, dashed line and dash-dotted line. These curves are in accordance with the temperature curves Ti and Ta Fig. 2 correlates, which occur during the heating up of the brick lining 2 and in the upper illustration of Fig. 5 are shown. This indicates that the heating is divided into three time periods or phases I, II and III.

As shown in the figure above Fig. 5 the temperature gradient can assume a constant value during phase II of the heating. Due to the process, there is a delayed increase for the temperature curve Ti in phase I when the lining 2 is heated, and a delayed decrease in phase III.

As shown in the illustration below Fig. 5 , namely according to the variant with continuous full line, the energy source can be controlled during the heating up of the brick lining in such a way that the temperature gradient dT / dx assumes a constant value in phase II, namely horizontally, and thereby 100% of the predetermined target value (dT / dx) _max . Alternatively, in accordance with the dash-dotted line in the lower representation of Fig. 5 , it is also possible that the temperature gradient dT / dx fluctuates over time during phase II. In the course of this, the temperature gradient dT / dx can briefly assume a value greater than 100% of the predetermined target value, for example for a desired shortening of the heating-up time. In exceptional cases, such a exceeding of the predetermined target value is possible without the brick lining 2 being damaged in the process.

In the lower representation of Fig. 5 the dashed line shows a further alternative for the time profile of the temperature gradient dT / dx, with the temperature gradient dT / dx being selected to be continuously smaller than the predetermined target value (dT / dx) _max in phase II of the heating-up time.

The variants for the course of the temperature gradient, which in the lower representation of Fig. 5 Shown with dash-dotted and dashed lines have in common that the course of the temperature gradient dT / dx is not constant, in particular during phase II of the heating, and can be variable over time.

In an application of the invention in the field of steel production, the above-mentioned method - due to a maximization of the heat flow that is introduced into the lining 2 - can reduce the process times for heating the ladle 1 while maintaining the life of the lining, because the maximum permissible thermal stresses are maintained or not exceeded. Another result of such a faster heating of the lining 2 is a considerable reduction in the losses which occur in the lining 2 during the heating phase. Finally, the possibility of faster heating also makes it possible to advantageously lower the temperature level at which a ladle 1 is kept ready for a subsequent use, thereby establishing a great potential for energy savings.

Claims (12)

1. Method for heating a walled-around item of equipment (1) in which the walling (2) of the equipment (1) is heated by an energy source (4),
   characterised in that
   during heating of the walling (2) a temperature gradient (dT/dx) created therein is detected and is used as a regulating variable for activation of the energy source (4) and
   the energy source (4) during heating of the walling (2) up to attainment of the target temperature thereof is controlled as a function of a predetermined target value for a temperature gradient (dT/dx) formed within the walling,
   wherein the predetermined target value for this temperature gradient is determined with consideration of at least one material characteristic value of the walling (2) formed from the maximum permissible thermal stress (σ_Tmax) thereof.
2. Method according to claim 1, characterised in that at least one sensor device (8) for detection of the temperature gradient (dT/dx) created therein is arranged within the walling (2), wherein the energy source (4) is connected in terms of measuring with the sensor device (8) by way of a regulating path and is correspondingly regulated in dependence on the measurement values of the sensor device (8) and as a function of the predetermined target value for the temperature gradient.
3. Method according to claim 2, characterised in that that a temperature present at a surface of the walling (2) adjacent to an action of the energy source (4), preferably adjacent to a flame of a burner or the like, is also detected by the sensor device (8).
4. Method according to any one of claims 1 to 3, characterised in that the energy source (4) is so controlled that during heating of the walling (2) a temperature gradient (dT/dx) created therein adopts a constant value.
5. Method according to any one of claims 1 to 4, characterised in that the energy source (4) is so controlled that during heating of the walling (2) a temperature gradient (dT/dx) created therein is variable over time.
6. Method according to any one of claims 1 to 5, characterised in that the energy source (4) is so controlled that during heating of the walling (2) a temperature gradient (dT/dx) created therein does not exceed a predetermined target value for the temperature gradient.
7. Method according to any one of claims 1 to 6, characterised in that the energy source (4) is so controlled that during heating of the walling (2) a temperature gradient (dT/dx) created therein is at least 80%, preferably at least 90%, more preferably at least 95%, of the predetermined target value for the temperature gradient.
8. Method according to any one of claims 1 to 7, characterised in that the control of the energy source (4) for heating the walling (2) is carried out in dependence on a databank (DB) in which measurement values relating to predetermined materials for the walling (2) to be heated are stored.
9. Method according to claim 8, characterised in that the data for activation of the energy source (4) are calculated simultaneously.
10. Method according to any one of claims 1 to 9, characterised in that the predetermined target value for the temperature gradient (dT/dx) is determined with consideration of the specific thermal capacity (c_p), the thermal conductivity (λ) and/or the density (p) of the walling (2).
11. Method according to any one of claims 8 to 10, characterised in that at least one temperature sensor by which during heating of the walling (2) a temperature within the interior space (I) of the walled-around equipment (1) is measured and transmitted to the databank (DB) is arranged in the interior space (I) of the walled-around equipment (1).
12. Method according to any one of claims 1 to 11, characterised in that the heating up is carried out in dependence on a predetermined instant for the target temperature of the walling (2) of the walled-around equipment (1) and the energy source (4) is suitably activated for that purpose.

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