Method for regulating an operation of an electric furnace and electric furnace for melting of melting material

Abstract

The present invention relates to a method for regulating an operation of an electric furnace (10) during a melting process of melting material, the method comprising the following method steps : - model predictive calculating (S1) of a target course of at least one operating property (Op) up to a time horizon (N) based on a result to be achieved of the melting process; and - setting (S2) the at least one operating property (Op) by means of the electrode positioning means (30) and / or the electrical power supply means (50) in such a way that the at least one operating property (Op) lies on the target course of the at least one operating property (Op) at a predetermined future point in time. The present invention further relates to an electric furnace (10) configured to execute a method for regulating an operation of an electric furnace (10) during a melting process of melting material.

Description

[0001] Method for regulating an operation of an electric furnace and electric furnace for melting of melting material

[0002] The present invention relates to a method for regulating an operation of an electric furnace during a melting process of melting material and an electric furnace configured to execute the method for regulating an operation of an electric furnace .

[0003] Melting material , especially metal s , are regularly melted and heated in melting units during a melting process . These electrically operated melting units , in particular electric furnaces such as electric arc furnaces , electric reduction furnaces and / or submerged arc-resistance furnaces , are operated with direct current ( DC ) , alternating current (AC ) or multiphase alternating current .

[0004] A melting process of melting material typically comprises at least one melting cycle . A melting cycle normally comprises di fferent operating steps such as , but not limited to : loading melting material , usually scrap and / or direct reduced iron ( DRI ) , into the furnace generating an electric arc between the melting material and electrodes of the furnace perforating the melting material in order to start the melting process forming a molten bath of the melting material refining the molten material to regulate the temperature of and the material composition of the molten bath dislagging the molten material present in the electric furnace tapping the molten material present in the electric fur- nace .

[0005] During the di f ferent operating steps of a melting cycle of a melting process , the operating properties of an electric furnace will exhibit di f ferent values dependent on a speci fic result to be achieved . The operating properties of an electric furnace include but are not limited to electrical voltage , electrical current , electrical frequency and electrode position . The speci fic results to be achieved with the melting process include but are not limited to minimi zing the time required to finish the melting process , minimizing the wear of the electric furnace and minimi zing the amount of electrical energy required to finish the melting process .

[0006] Conventional methods for regulating an operation of an electric furnace during a melting process of melting material set the operating properties of an electric furnace following a fixed target course of these operating properties depending on the given melting material and the speci fic result to be achieved . In this way for instance , a fixed given target amount of electric power to be trans ferred to the melting material in a speci fic operating step of the melting cycle is achieved by adj usting for instance the electrode position and / or the electrical current and / or the electrical voltage .

[0007] However, these known types of methods for regulating an operation of an electric furnace during a melting process of melting material have a disadvantage linked to the wide variation of instantaneous power absorption which is taken from the power network and which occurs in particular, but not limited to , during the perforation of the melting material . The collapse of the melting material causes short circuits and disturbances in the electric arc . Given this instantaneous variability in power absorption by the electric furnace , voltage fluctuations in the supplying power network are generated, causing the so-called flicker phenomenon . This instantaneous variability in power absorption can be measured by the so-called dynamic factor . The dynamic factor is defined as the ratio between the measured actual reactance of an overall electric furnace and the reactance within the electric circuitry of an electric furnace . Further, this instantaneous variability in power absorption by the electric furnace causes non-optimal process conditions such as increased wear, particularly electrode and furnace wear, as well as increased consumption of electrical energy for a given amount of melting material .

[0008] The present invention is based on the problem, to provide a method for regulating an operation of an electric furnace during a melting process of melting material that is capable to reduce the instantaneous variability in power absorptions by the electric furnace and therefore to also minimi ze the dynamic factor throughout a melting process of melting material .

[0009] The problem underlying the present invention is solved by a method for regulating an operation of an electric furnace during a melting process of melting material according to claim 1 . Advantageous embodiments of the method are described in the claims dependent on claim 1 .

[0010] In more detail , the problem underlying the present invention is solved by a method for regulating an operation of an electric furnace during a melting process of melting material , said electric furnace comprising an electrode positioning means for positioning at least one electrode (preferably a plurality, e . g . two or three or more electrodes ) of the electric furnace , an electrical power supply means for supplying electric power to said at least one electrode and an electronic control means data-coupled to the electrode positioning means and the electrical power supply means for transmitting signals . The method comprising the following method steps : model predictive calculating of a target course of at least one operating property up to a time hori zon based on a result to be achieved of the melting process ; and setting the at least one operating property by means of the electrode positioning means and / or the electrical power supply means in such a way that the at least one operating property lies on the target course of the at least one operating property at a predetermined future point in time .

[0011] The method according to the invention has the advantage , that the deviation of at least one operating property from its optimal value at any given point in time is reduced signi ficantly . This results in a signi ficant reduction of the instantaneous variability in power absorptions by the electric furnace and thus helps to reduce flicker in a supplying power network and at the same time increase overall energy ef ficiency of the electric furnace . For instance , the deviation of the electrical current of the at least one electrode from its optimal value at any given point in time for a minimum amount of electrical energy required to heat the melting material to a predetermined temperature is reduced .

[0012] A melting process may comprise one or more melting cycles . A melting cycle may comprise the following operating steps : loading melting material , usually scrap and / or direct reduced iron ( DRI ) , into the furnace generating an electric arc between the melting material and electrodes of the furnace perforating the melting material in order to start the melting process forming a molten bath of the melting material refining the molten material to regulate the temperature of and the material composition of the molten bath dislagging the molten material present in the electric furnace tapping the molten material present in the electric furnace .

[0013] A melting cycle may further comprise additional operating steps that can be performed in sequence to and / or in parallel to the operating steps mentioned above such as , but not limited to : using gas burners and / or oxygen lances to additionally heat the melting material , adj usting the chemical composition of the melting material by using oxygen lances within the melting material , adj usting the chemical composition of the melting material by inj ecting additives like carbon, lime and / or dolomite or any combination theses additives to the melting material .

[0014] A melting cycle may comprise further operating steps specific to speci fic melting materials and / or results to be achieved during the melting process . Further operating steps of a melting cycle might include inj ecting the molten material with additives and / or alloy elements . Speci fic operating steps of a melting cycle may be repeated several times within one melting cycle .

[0015] An electric furnace may be an electric arc furnace , an electric reduction furnace or a submerged arc-resistance furnace . An electric furnace may be operated with direct current ( DC ) , alternating current (AC ) or multiphase alternating current .

[0016] A melting material may comprise a metal material , particularly a steel material , and / or a direct reduced iron material . A melting material may comprise scrap material , particularly scrap metal material . A melting material may comprise aluminum, copper, silver, gold or any other metal material that can be heated and / or melted with electric energy .

[0017] An electrode may be produced from high density graphite and / or Wol fram . An electrode may be designed to trans fer electrical energy forming arcs between its tip and charge material . An electrode can be a prebaked electrode or a sel f-baking electrode ( Soederberg electrode ) and / or an extrusion / composite electrode , which is a combination of a Soederberg electrode with a prebaked electrode as a core and / or a hollow electrode system, whereby the selection of the type of electrode can depend on the si ze of the electrode , produced material / metallurgy, and / or economic aspects such as operational costs .

[0018] An electrode positioning means may comprise a height adj ustment means configured to move the at least one electrode of the electric furnace nearer to or away from the melting material in the electric furnace . The height adj ustment means can use either electric winch hoists , hydraulic cylinders , pneumatic cylinders , direct electro-mechanical drives comprising an electric motor and / or a gear or the like . In this way the position of the at least one electrode can be adj usted faster and with increased accuracy .

[0019] An electrical power supply means may comprise a plurality of converters configured to supply electric power to at least one electrode of the electric furnace .

[0020] An electrical power supply means may comprise a plurality of DC-AC converters and / or AC-DC-AC converters configured to supply electric power to at least one electrode of the electric furnace . In this way, an electric furnace can be operated with alternating current , particularly with multiphase alternating current . An electrical power supply means may comprise a plurality of AC-DC converters and / or DC-DC converters and / or DC-choppers configured to supply electric power to at least one electrode of the electric furnace . In this way, an electric furnace can be operated with direct current .

[0021] An electronic control means may be any electronic system, which is adapted to receive signals and / or to store signals and / or to process signals and / or to transmit signals . An electronic control means may be any electronic system, which is adapted to control and / or regulate an electrical power supply means in dependence on at least one signal and / or to control and / or regulate an electrode positioning means in dependence on at least one signal .

[0022] The electric furnace may comprise one or more sensors to provide information about harmonic distortions and / or flicker and / or a ratio of active power flow and reactive power flow in the supplying power network and / or at least one operating property o f the electric furnace . The electronic control means may be operatively connected to one or more such sensors and can receive sensor signals , process them, and use them to control and / or regulate the electrical power supply means and / or the electrode positioning means .

[0023] The one or more sensors may be sensors using optical measuring means and / or electrical measuring means and / or magnetic measuring means and / or mechanical measuring means and / or magnetostrictive measuring means to measure one or more measuring quantities in order to provide sensor signals to an electronic control means .

[0024] The one or more measuring quantities may correspond directly and / or indirectly to harmonic distortions and / or flicker and / or a ratio of active power flow and reactive power flow in the supplying power network and / or at least one actual operating property of the electric furnace . In this way, the pos itioning of the sensors within the electric furnace can be more flexible .

[0025] For example , i f the at least one actual operating property is an electrical current , the at least one measuring quantity may correspond directly to the electrical current . In other words , the measuring quantity may be the electrical current .

[0026] For example , i f the at least one actual operating property is an electrode position, the at least one measuring quantity may correspond indirectly to the electrode position . In other words , the measuring quantity may be a pressure inside a hydraul ic cylinder used to position the at least one electrode , wherein the pressure inside the hydraulic cylinder corresponds to a speci fic electrode position with regard to a melting material in an electric furnace .

[0027] The electronic control means may comprise a storing element configured to store sensor signals received by one or more sensors from the electric furnace .

[0028] The electronic control means may comprise a housing . The electronic control unit may be an integral component .

[0029] A housing in the context of this invention is designed to protect the designated components inside from external influences , in particular from mechanical and / or electrical influences . Furthermore , a housing can be provided with an electrical ground connection so that the housing can increase the safety for personnel in the vicinity of the electrical components enclosed by the housing in a designated manner .

[0030] A housing can comprise a bottom part , a top part and at least one side part . The bottom part , the top part and at least one side part can limit a housing volume at least partially . The bottom part , the top part and at least one side part may be connected to each other forming an integral component .

[0031] Two parts forming an integral component in the context of this invention are interconnected with each other by means of at least one mechanical connection . In other words , two parts forming an integral component change their relative spatial position to each other within the limits of their mechanical connection when the integral component is moved from one spatial position to another spatial position .

[0032] In a preferred embodiment of the invention, the mechanical connection of an integral component is fixed . In other words , the relative position of two parts forming an integral component , wherein the mechanical connection between the two parts is fixed, is constant during change of a spatial position of the integral component .

[0033] A model predictive calculating is based on mathematical formulas to describe the functional and physical correlations of an electric furnace during a melting process of melting material known to the person skilled in the art .

[0034] An operating property may be any property of an electric furnace during operation of that electric furnace . For instance , an operating property may be an electrical voltage , an electrical current , an electrical frequency, an electrode position or the like .

[0035] A target course of an operating property is a predetermined course of that operating property which is calculated in order to achieve a speci fic result of a melting process . A time hori zon may be any amount of time , particularly the amount of time from beginning of a melting process until the end of that melting process .

[0036] A result to be achieved of a melting process may apply to the entire melting process and / or to speci fic operating steps of a melting cycle of the melting process . For instance , minimi zing the electrical energy required to heat a speci fic amount o f melting material to a predetermined temperature may apply to the entire melting process and / or to speci fic operating steps of a melting cycle of the melting process . Di f ferent operating steps of a melting cycle of a melting process may comprise di f ferent results to be achieved . For instance , in the operating step of perforating the melting material in order to start the melting process the result to be achieved may be minimi zing the time required to heat the melting material to a predetermined temperature . In the subsequent operating step of forming a molten bath of the melting material , the result to be achieved may be minimi zing the electrical energy required to heat the melting material to a predetermined temperature . A method designed in such a way has the advantage , that energy ef ficiency and time ef ficiency of the melting process can be increased while at the same time the quality of the melting material at exit of the furnace can be increased .

[0037] Further preferably, the method is designed in such a way that the method exhibits a method step for determining at least one actual operating property which is supplied to the at least one electrode by means of the electrode positioning means and / or the electrical power supply means at a first time , and in that the method step of the model predictive calculating of the target course of the at least one operating property up to the time hori zon is conducted in such a way that the target course of the at least one operating property at the first time is equal to the actual operating property at the first time . In this way, overall control and regulation of the electric furnace can be improved . The target course of the at least one operating property is continuously updated and thus allows for a more precise control and regulation of the at least one operating property even accounting for sudden changes in conditions within the electric furnace during the melting process . In fact , the target course is no longer a static target course as known from the state of the art but instead is calculated continuously throughout the melting process resulting in an improved control and regulation of the electric furnace based on a predictive control and regulation rather than on traditional correctionbased control and regulation .

[0038] The method step for determining at least one actual operating property at a f irst time may be conducted by means of at least one sensor .

[0039] Further preferably, the method is designed in such a way that the method exhibits a method step for setting the at least one operating property in such a way that the at least one operating property is at the target course at a second time following the first time in terms of time .

[0040] In this way, the method has the advantage , that overall control and regulation of the electric furnace can even be more improved, because the at least one operating property can follow the target course faster allowing for an increase in control and regulation velocity .

[0041] The feature that the second time follows the first time in terms of time can also be expressed in the way that the second time is after or downstream of the first time in terms of time . Further preferably, the method is designed in such a way that the method exhibits a method step for determining at least one actual operating property which is supplied to the at least one electrode by means of the electrode positioning means and / or the electrical power supply means at a third time , the third time following the second time in terms of time , and in that the method step of the model predictive calculation of the target course of the at least one operating property up to the time hori zon is conducted in such a way that the target course of the at least one operating property at the third time is equal to the actual operating property at the third time .

[0042] In this way, the method has the advantage , that overall control and regulation of the electric furnace can even further be improved, because the target course of the at least one operating property is continuously updated and thus also takes sudden changes of conditions within the electric furnace during the melting process into account . Such changes may be , but are not limited to sudden changes in electrode position with regard to the melting material due to collapses of melting material during the melting process .

[0043] The feature that the third time follows the second time in terms of time can also be expressed in the way that the third time is after or downstream of the second time in terms of time .

[0044] Further preferably, the method is designed in such a way that the method exhibits a method step for setting the at least one operating property in such a way that the at least one operating property is at the target course at a fourth time following the third time in terms of time .

[0045] In this way, the method has the advantage , that overall control and regulation of the electric furnace can again even further be improved, because the at least one operating property can follow the target course faster allowing for an increase in control and regulation velocity .

[0046] The feature that the fourth time follows the third time in terms of time can also be expressed in the way that the fourth time is after or downstream of the third time in terms of time .

[0047] The first time , the second time , the third time and the fourth time may lie within the scope of the time hori zon .

[0048] The method steps described above may be continued continuously throughout the melting process within the time hori zon .

[0049] Further preferably, the method is designed in such a way that the method exhibits the following method steps : model predictive calculating of target courses of n operating properties up to a time hori zon based on a result to be achieved of the melting process ; and setting the n operating properties by means of the electrode positioning means and / or the electrical power supply means in such a way that the respective n operating properties lie at a predetermined future point in time on the respective target courses associated with the respective operating properties .

[0050] In this way, the method has the advantage , to improve the overal l control and regulation of the electric furnace by enabling a simultaneous control and regulation of a plurality of operating properties .

[0051] The number n of operating properties is not limited to a speci fic amount but can be any integer number . For instance n can be equal to or higher than 2 , preferably equal to or higher than 5 and especially preferred equal to or higher than 35 . In a preferred embodiment , the number n of operating properties can be equal to

[0052] 4 .

[0053] Further preferably, the method is designed in such a way that the method exhibits a method step for determining n actual operating properties which are supplied to the at least one electrode by means of the electrode positioning means and / or the electrical power supply means at a first time , and in that the method step of the model predictive calculating of respective target courses of the n operating properties up to the time hori zon is conducted in such a way that the respective target courses of the respective operating properties at the first time are equal to the respective actual operating properties at the first time .

[0054] In this way, the method has the advantage , that overall control and regulation of the electric furnace can even further be improved, because the target course of the n operating properties are continuously updated and thus also take sudden changes of conditions within the electric furnace during the melting process into account . Such changes may be , but are not limited to sudden changes in electrode position with regard to the melting material due to collapses of melting material during the melting process .

[0055] Further preferably, the method is designed in such a way that the method exhibits a method step for setting the n operating properties in such a way that the n operating properties are at the respective target courses at a second time following the first time in terms of time .

[0056] In this way, the method has the advantage , that overall control and regulation of the electric furnace can even be more improved, because the n operating properties can follow the target courses faster allowing for an increased control and regulation velocity .

[0057] Further preferably, the method is designed in such a way that the method exhibits a method step for determining n actual operating properties which are supplied to the at least one electrode by means of the electrode positioning means and / or the electrical power supply means at a third time , the third time following the second time in terms of time , and in that the method step of the model predictive calculating of the respective target courses of the n operating properties up to the time hori zon is conducted in such a way that the respective target courses of the respective operating properties at the third time are equal to the respective actual operating properties at the third time .

[0058] In this way, the method has the advantage , that overall control and regulation of the electric furnace can even further be improved, because the target courses of the n operating properties are continuously updated and thus also take into account sudden changes of conditions within the electric furnace during the melting process . Further, the target courses of the n operating properties are updated over a continuous time within the time hori zon allowing for increased control and regulation velocity over an extended period of time .

[0059] Further preferably, the method is designed in such a way that the method exhibits a method step for setting the n operating properties in such a way that the n operating properties are at the respective target courses at a fourth time following the third time in terms of time .

[0060] In this way, the method has the advantage , that overall control and regulation of the electric furnace can even be more improved, because the n operating properties can follow the target courses faster and over a continuous time within the time hori zon allowing for an increased control and regulation velocity .

[0061] Further preferably, the method is designed in such a way that at least one operating property and / or at least one actual operating property is an electrical voltage .

[0062] In this way, the method has the advantage , to allow for an instantaneous control and regulation of the electric power supplied to the at least one electrode .

[0063] The electrical voltage may be the electrical voltage applied to the at least one electrode .

[0064] Further preferably, the method is designed in such a way that at least one operating property and / or at least one actual operating property is an electrical current .

[0065] In this way, the method has the advantage , to allow for an instantaneous control and regulation of the electric power supplied to the at least one electrode .

[0066] The electrical current may be the electrical current supplied to the at least one electrode .

[0067] Further preferably, the method is designed in such a way that at least one operating property and / or at least one actual operating property is an electrical frequency .

[0068] In this way, the method has the advantage , to increase the power factor of electric power flowing through the at least one electrode by allowing for an instantaneous control and regulation of the ratio of active power flow and reactive power flow supplied to the at least one electrode . The electrical frequency may be the electrical frequency appl ied to the at least one electrode .

[0069] Further preferably, the method is designed in such a way that at least one operating property and / or at least one actual operating property is an electrode position of the at least one electrode .

[0070] In this way, the method has the advantage that wear of the at least one electrode can be signi ficantly reduced .

[0071] The electrode position may be the electrode position relative to the melting material inside an electric furnace in a vertical direction .

[0072] Further preferably, the method is designed in such a way that the model predictive calculation of the at least one target course of the at least one operating property is based on a discrete time dynamic model of the melting process of the melting material in the electric furnace , wherein a time interval between two successive time steps is smaller than or equal to 0 . 1 s .

[0073] In this way, the method has the advantage , that the accuracy of the control and regulation of the electric furnace is improved because determining at least one actual operating property and setting at least one operating property can be conducted at a higher sampling resolution .

[0074] Preferably, the time interval between two successive time steps of the time dynamic model of the melting process of the melting material is smaller than or equal to 0 . 01 s , further preferably smaller than or equal to 0 . 001 s and especially preferred smal ler than or equal to 0 . 0005 s . In this way, the method has the advantage , that the accuracy of the control and regulation of the electric furnace is even further improved because determin- ing at least one actual property and setting at least one operating property can be conducted at an even higher sampling resolution .

[0075] According to a preferred embodiment, the time interval between two successive time steps of the time dynamic model of the melting process of the melting material is higher than or equal to 0.0001 s, further preferably higher than or equal to 0.0005 s and especially preferred higher than or equal to 0.001 s.

[0076] According to a preferred embodiment, the time interval between two successive time steps of the time dynamic model of the melting process of the melting material is lying in a time range from 0.0002 s to 0.1 s, preferably in a time range from 0.001 s to 0.1 s and especially preferably in a time range from 0.01 s to 0.1 s .

[0077] Further preferably, the method is designed in such a way that the result of the melting process to be achieved is selected from the group comprising: minimizing the electrical energy required to heat the melting material to a predetermined temperature; minimizing the time required to heat the melting material to a predetermined temperature; and minimizing wear of the at least one electrode for heating the melting material to a predetermined temperature .

[0078] In this way, the method has the advantage, that overall operational cost of a melting process of melting material with an electric furnace can be reduced while at the same time service life of that electric furnace can be increased. In a preferred embodiment, the method is designed in such a way, that the result of the melting process to be achieved is selected from the group comprising: minimizing and / or equalizing wear of the refractory vessel of the electric furnace; minimizing and / or equalizing wear of the panels of the electric furnace; minimizing and / or equalizing wear of the bottom shell of the refractory vessel of the electric furnace; minimizing and / or equalizing wear of the slag door of the electric furnace; minimizing and / or equalizing wear of the top lid of the electric furnace; optimizing the reheating of a raw material discharging zone and / or an injection zone and / or a tapping zone, especially an eccentric bottom tapping zone within the electric furnace vessel; optimizing the reheating of a chemical additive material discharging zone and / or a chemical additive material injection zone within the electric furnace vessel; and optimizing the reheating of the slag door zone within the electric furnace vessel; and minimizing harmonic distortions and / or flicker in a supplying power network; and maximizing the ratio of active power flow and reactive power flow in the supplying network.

[0079] Equalizing wear of a specific part of the electric furnace can be understood in that wear is substantially uniform over a given surface of the specific part of the electric furnace. In that way, service life of the overall electric furnace can be increased . The invention is further based on the problem, to provide an electric furnace , wherein the instantaneous variability in power absorptions by the electric furnace during a melting process of melting material is reduced .

[0080] This problem underlying the present invention is solved by an electric furnace according to claim 17 .

[0081] In more detail , the problem underlying the present invention is solved by an electric furnace for melting material , wherein the electric furnace comprises an electrode positioning means for positioning at least one electrode of the electric furnace . The electric furnace further comprises an electrical power supply means for supplying electric power to said at least one electrode . Moreover, the electric furnace comprises an electronic control means data-coupled to the electrode positioning means and the electrical power supply means for transmitting signals . The electric furnace is characteri zed in that the electronic control means is adapted to regulate an operation of the electric furnace during a melting process of the melting material according to any of the above described methods .

[0082] Further advantages , details and features of the present invention are explained in the description of the following embodiments , thereby :

[0083] Figure 1 : shows a flow chart diagram of a first embodiment of the method for regulating an operation of an electric furnace during a melting process of melting material ;

[0084] Figure 2 : shows a flow chart diagram of a second embodiment of the method for regulating an operation of an electric furnace during a melting process of melting material ; Figure 3 : shows a diagram showing a target course of an operating property of an electric furnace during a melting process over a time hori zon N based on a result to be achieved and the actual operating property up to a first time tl ;

[0085] Figure 4 : shows a diagram showing a target course of an operating property of an electric furnace during a melting process over a time hori zon N based on a result to be achieved and the actual operating property up to a second time t2 ;

[0086] Figure 5 : shows a diagram showing a target course of an operating property of an electric furnace during a melting process over a time hori zon N based on a result to be achieved and the actual operating property up to a fourth time t4 ; and

[0087] Figure 6 : shows a schematic view of an electric furnace for melting material according to a first embodiment .

[0088] In the following description, same reference numerals describe same elements and same features , respectively, so that a description of one element conducted with reference to one figure is also valid for the other figures , so that repetition of the respective feature is omitted .

[0089] Figure 1 shows a flow chart diagram of a first embodiment of the method for regulating an operation of an electric furnace 10 during a melting process of melting material . The electric furnace 10 shown in figure 6 comprises an electrode positioning means 30 for positioning at least one electrode 40 of the electric furnace 10 , an electrical power supply means 50 for supplying electric power to said at least one electrode 40 and an electronic control means 60 data-coupled to the electrode positioning means 30 and the electrical power supply means 50 for transmitting signals .

[0090] The method comprises the following method steps : model predictive calculating S I of a target course of at least one operating property Op up to a time hori zon N based on a result to be achieved of the melting process ; setting S2 the at least one operating property Op by means of the electrode positioning means 30 and / or the electrical power supply means 50 in such a way that the at least one operating property Op lies on the target course of the at least one operating property Op at a predetermined future point in time ; determining S3 at least one actual operating property Oap which is suppl ied to the at least one electrode 40 by means of the electrode positioning means 30 and / or the electrical power supply means 50 at a first time tl , wherein the method step of the model predictive calculating S I of the target course of the at least one operating property Op up to the time hori zon N is conducted in such a way that the target course of the at least one operating property Op at the first time tl is equal to the actual operating property Oap at the first time tl .

[0091] The method further comprises the following method steps : setting S4 the at least one operating property Op in such a way that the at least one operating property Op is at the target course at a second time t2 following the first time tl in terms of time ; determining S5 at least one actual operating property Oap which is supplied to the at least one electrode 40 by means of the electrode positioning means 30 and / or the electrical power supply means 50 at a third time t3 , the third time t3 following the second time t2 in terms of time , wherein the model predictive calculation S I of the target course of the at least one operating property Op up to the time hori zon N is conducted in such a way that the target course of the at least one operating property Op at the third time t3 is equal to the actual operating property Oap at the third time t3 , and setting S 6 the at least one operating property Op in such a way that the at least one operating property Op is at the target course at a fourth time t4 following the third time t3 in terms of time .

[0092] Figure 2 shows a flow chart diagram of a second embodiment of the method for regulating an operation of an electric furnace 10 during a melting process of melting material .

[0093] The method comprises the following method steps : model predictive calculating S7 of target courses of n operating properties Op up to a time hori zon N based on a result to be achieved of the melting process ; setting S 8 the n operating properties Op by means of the electrode positioning means 30 and / or the electrical power supply means 50 in such a way that the respective n operating properties Op lie at a predetermined future point in time on the respective target courses associated with the respective operating properties Op, and determining S 9 n actual operating properties Oap which are supplied to the at least one electrode 40 by means of the electrode positioning means 30 and / or the electrical power supply means 50 at a first time tl , wherein the method step of the model predictive calculating S7 of respective target courses of the n operating properties Op up to the time horizon N is conducted in such a way that the respective target courses of the respective operating properties Op at the first time tl are equal to the respective actual operating properties Oap at the first time tl .

[0094] The method further comprises the following method steps : setting S 10 the n operating properties Op in such a way that the n operating properties Op are at the respective target courses at a second time t2 following the first time tl in terms of time ; determining S i l n actual operating properties Oap which are supplied to the at least one electrode 40 by means of the electrode positioning means 30 and / or the electrical power supply means 50 at a third time t3 , the third time t3 following the second time t2 in terms of time , wherein the method step of the model predictive calculating S7 of the respective target courses of the n operating properties Op up to the time horizon N is conducted in such a way that the respective target courses of the respective operating properties Op at the third time t3 are equal to the respective actual operating properties Oap at the third time t3 , and setting S 12 the n operating properties Op in such a way that the n operating properties Op are at the respective target courses at a fourth time t4 following the third time t3 in terms of time .

[0095] Figure 3 shows a diagram of a target course of an operating property of an electric furnace during a melting process over a time hori zon N based on a result to be achieved and the actual operating property up to a first time tl . The target course of at least one operating property Op up to a time hori zon N is calculated in a method step of model predictive calculating S I . The at least one operating property Op is set in method step S2 by means of the electrode positioning means 30 and / or the electrical power supply means 50 in such a way that the at least one operating property Op lies on the target course of the at least one operating property Op at a predetermined future point in time . This is displayed by the first "x" in the diagram when starting to count the number of "x" from the left side of the diagram .

[0096] The at least one actual property Oap which is suppl ied to the at least one positioning means 30 and / or the electrical power supply means 50 at a first time tl is determined in method step S3 . The method step of model predictive calculating S I of the target course of the at least one operating property Op up to a time hori zon N in turn is conducted in such a way, that the target course of the at least one operating property Op at the first time tl is equal to the actual operating property Oap at the first time t l . This is displayed by the second "x" in the diagram . As can be seen, the actual operating property Oap and the target course of the operating property Op coincide at the first time tl . In thi s way, the target course of the operating property Op is continuously updated throughout the melting process of melting material taking into account the actual operating property Oap . This results in a more accurate control and regulation of the operating property and thus results in an increased overall ef ficiency of the melting process .

[0097] Figure 4 shows a diagram of a target course of an operating property of an electric furnace during a melting process over a time hori zon N based on a result to be achieved and the actual operating property up to a second time t2 . The at least one operating property Op is set in a method step S4 in such a way that the at least one operating property Op is at the target course at a second time t2 following the first time tl in terms of time . This is displayed be the third "x" in the diagram .

[0098] Figure 5 shows a diagram showing a target course of an operating property of an electric furnace during a melting process over a time hori zon N based on a result to be achieved and the actual operating property up to a fourth time t4 .

[0099] The at least one actual property Oap which is suppl ied to the at least one positioning means 30 and / or the electrical power supply means 50 at a third time t3 , the third time t3 following the second time t2 , is determined in method step S5 . The method step of model predictive calculating S I of the target course of the at least one operating property Op up to a time hori zon N in turn i s conducted in such a way, that the target course of the at least one operating property Op at the third time t3 is equal to the actual operating property Oap at the third time t3 . This is displayed by the fourth "x" in the diagram . As can be seen, the actual operating property Oap and the target course of the operating property Op coincide at the third time t3 . In this way, the target course of the operating property Op is continuously updated throughout the melting process of melting material taking into account the actual operating property Oap .

[0100] The at least one operating property Op is set in method step S 6 in such a way that the at least one operating property Op is at the target course at a fourth time t4 following the third time t3 in terms o f time . Thi s is displayed by the fi fth "x" in the diagram .

[0101] Figure 6 shows a schematic view of an electric furnace 10 for melting material in a first embodiment . The electric furnace 10 comprises two electrode positioning means 30 for positioning two electrodes 40 of the electric furnace 10 . Each electrode positioning means 30 is connected to only one electrode 40 and and each electrode 40 is connected to only one electrode positioning mean 30 . The electrodes 40 are positioned in a furnace vessel 70 with melting material . The electric furnace 10 further comprises an electrical power supply means 50 for supplying electric power to the two electrodes 40 . The electrical power supply means 50 is connected to both electrodes 40 . The electric furnace 10 further comprises an electronic control means 60 , wherein the electronic control means 60 is data-coupled to the two electrode positioning means 30 and the electrical power supply means 50 for transmitting signals . The electrode control means 60 is further adapted to regulate an operation of the electric furnace 10 during a melting process of the melting material according to the method for regulating an operation of an electric furnace 10 during a melting process of melting material as described above .

[0102] List of reference numerals

[0103] 10 Electric furnace

[0104] 30 Electrode positioning means

[0105] 40 Electrode

[0106] 50 Electrical power supply means

[0107] 60 Electronic control means

[0108] 70 Furnace vessel

[0109] Op Operating property

[0110] Oap Actual operating property

[0111] N Time hori zon

[0112] Up Electrical voltage

[0113] Ip Electrical current

[0114] Fp Electrical frequency tl First time t2 Second time t3 Third time t4 Fourth time

[0115] 51 Method step S I

[0116] 52 Method step S2

[0117] 53 Method step S3

[0118] 54 Method step S4

[0119] 55 Method step S5

[0120] 56 Method step S 6

[0121] 57 Method step S7

[0122] 58 Method step S 8

[0123] 59 Method step S 9

[0124] 510 Method step S 10

[0125] 511 Method step S i l

[0126] 512 Method step S 12

Claims

Claims1. A method for regulating an operation of an electric furnace (10) during a melting process of melting material, said electric furnace (10) comprising: an electrode positioning means (30) for positioning at least one electrode (40) of the electric furnace (10) ; an electrical power supply means (50) for supplying electric power to said at least one electrode (40) ; and an electronic control means (60) data-coupled to the electrode positioning means (30) and the electrical power supply means (50) for transmitting signals, the method comprising the following method steps: model predictive calculating (SI) of a target course of at least one operating property (Op) up to a time horizon (N) based on a result to be achieved of the melting process; and setting (S2) the at least one operating property (Op) by means of the electrode positioning means (30) and / or the electrical power supply means (50) in such a way that the at least one operating property (Op) lies on the target course of the at least one operating property (Op) at a predetermined future point in time.

2. Method according to claim 1, characterized in that the method exhibits a method step for determining (S3) at least one actual operating property (Oap) which is supplied to the at least one electrode (40) by means of the electrode positioning means (30) and / or the electrical power supply means (50) at a first time ( 11 ) , and in that the method step of the model predictive calculating (SI) of the target course of the at least oneoperating property (Op) up to the time horizon (N) is conducted in such a way that the target course of the at least one operating property (Op) at the first time (tl) is equal to the actual operating property (Oap) at the first time (tl) .

3. Method according to claim 2, characterized in that the method exhibits the following method step: setting (S4) the at least one operating property (Op) in such a way that the at least one operating property (Op) is at the target course at a second time (t2) following the first time (tl) in terms of time.

4. Method according to claim 3, characterized in that the method exhibits a method step for determining (S5) at least one actual operating property (Oap) which is supplied to the at least one electrode (40) by means of the electrode positioning means (30) and / or the electrical power supply means (50) at a third time (t3) , the third time (t3) following the second time (t2) in terms of time, and in that the method step of the model predictive calculation (SI) of the target course of the at least one operating property (Op) up to the time horizon (N) is conducted in such a way that the target course of the at least one operating property (Op) at the third time (t3) is equal to the actual operating property (Oap) at the third time (t3) .

5. Method according to claim 4, characterized in that the method exhibits the following method step: setting (S6) the at least one operating property (Op) in such a way that the at least one operating property (Op) is at the target course at a fourth time (t4) following the third time (t3) in terms of time.

6. Method according to any of the preceding claims, characterized in the following method steps: model predictive calculating (S7) of target courses of n operating properties (Op) up to a time horizon (N) based on a result to be achieved of the melting process; and setting (S8) the n operating properties (Op) by means of the electrode positioning means (30) and / or the electrical power supply means (50) in such a way that the respective n operating properties (Op) lie at a predetermined future point in time on the respective target courses associated with the respective operating properties (Op) .

7. Method according to claim 6, characterized in that the method exhibits a method step for determining (S9) n actual operating properties (Oap) which are supplied to the at least one electrode (40) by means of the electrode positioning means (30) and / or the electrical power supply means (50) at a first time ( 11 ) , and in that the method step of the model predictive calculating (S7) of respective target courses of the n operating properties (Op) up to the time horizon (N) is conducted in such a way that the respective target courses of the respective operating properties (Op) at the first time (tl) are equal to the respective actual operating properties (Oap) at the first time (tl) .

8. Method according to claim 7, characterized in that the method exhibits the following method step: setting (S10) the n operating properties (Op) in such a way that the n operating properties (Op) are at therespective target courses at a second time (t2) following the first time (tl) in terms of time.

9. Method according to claim 8, characterized in in that the method exhibits a method step for determining (Sil) n actual operating properties (Gap) which are supplied to the at least one electrode (40) by means of the electrode positioning means (30) and / or the electrical power supply means (50) at a third time (t3) , the third time (t3) following the second time (t2) in terms of time, and in that the method step of the model predictive calculating (S7) of the respective target courses of the n operating properties (Op) up to the time horizon (N) is conducted in such a way that the respective target courses of the respective operating properties (Op) at the third time (t3) are equal to the respective actual operating properties (Gap) at the third time (t3) .

10. Method according to claim 9, characterized in that the method exhibits the following method step: setting (S12) the n operating properties (Op) in such a way that the n operating properties (Op) are at the respective target courses at a fourth time (t4) following the third time (t3) in terms of time.

11. Method according to one of the preceding claims, characterized in that at least one operating property (Op) and / or at least one actual operating property (Gap) is an electrical voltage (Up) .

12. Method according to one of the preceding claims, characterized in that at least one operating property (Op) and / or at least one actual operating property (Gap) is an electrical current ( Ip) .

13. Method according to one of the preceding claims, characterized in that at least one operating property (Op) and / or at least one actual operating property (Oap) is an electrical frequency (Fp) .

14. Method according to one of the preceding claims, characterized in that at least one operating property (Op) and / or at least one actual operating property (Oap) is an electrode position of the at least one electrode (40) .

15. Method according to one of the preceding claims, characterized in that the model predictive calculation of the at least one target course of the at least one operating property (Op) is based on a discrete time dynamic model of the melting process of the melting material in the electric furnace (10) , wherein a time interval between two successive time steps is smaller than or equal to 0.1 s.

16. A method according to any one of the preceding claims, characterized in that the result of the melting process to be achieved is selected from the group comprising: minimizing the electrical energy required to heat the melting material to a predetermined temperature; minimizing the time required to heat the melting material to a predetermined temperature; and minimizing wear of the at least one electrode (40) for heating the melting material to a predetermined temperature .

17. Electric furnace (10) for melting material, said electric furnace (10) comprising: an electrode positioning means (30) for positioning at least one electrode (40) of the electric furnace (10) ;an electrical power supply means (50) for supplying electric power to said at least one electrode (40) ; and an electronic control means (60) data-coupled to the electrode positioning means (30) and the electrical power supply means (50) for transmitting signals, wherein the electric furnace (10) is characterized in that the electronic control means (60) is adapted to regulate an operation of the electric furnace (10) during a melting process of the melting material according to any of the preceding claims.

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