Novel electric furnace and method for judging melting state of scrap steel in furnace

Abstract

The invention relates to a novel electric furnace and a method for judging the melting state of waste steel in the electric furnace, belongs to the technical field of waste steel melting, and solves the problems that in the prior art, the electric furnace waste steel melting state lacks a quantitative evaluation method, and waste steel melting state errors are large and are easily interfered by means such as electric furnace noise recognition based on experience. The invention discloses a novel electric furnace. The electric furnace comprises an electric furnace main body and a consumable electrode control device, the control device is provided with an encoder and a pull rope, and height data of the consumable electrode can be monitored in real time. According to the electric furnace, the position of the electrode is accurately monitored in real time, and the melting state of waste steel in the furnace can be recognized in combination with a matched judgment method; and meanwhile, recognition and analysis of the electrode end image and the furnace door image are further combined, so that the melting state of the scrap steel in the furnace can be evaluated more accurately, the smelting production efficiency of the electric furnace is improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metal smelting, and in particular to a novel electric furnace and a method for judging the melting state of scrap steel in the furnace. Background Art

[0002] At present, during the smelting process of electric furnaces, the melting state of scrap steel in the electric furnace is the main factor affecting the production of electric furnaces using scrap steel as raw materials. First, the melting state of scrap steel directly affects the selection of the electric furnace power supply curve, and the selection of the electric furnace power supply curve directly affects the electric furnace power factor; secondly, the melting state of scrap steel is the main basis for the addition period and amount of slag to the electric furnace, so the determination of the melting state of scrap steel can be used as an important reference in the production process of electric furnaces. At present, there is no mature solution for the determination of the melting state of scrap steel in electric furnaces, which has become a difficult problem that electric furnace manufacturers in the steel industry need to solve urgently. Since the density of scrap steel is greater than that of molten steel, the melting process of scrap steel will be accompanied by the phenomenon of rising molten pool liquid level. By detecting the change in liquid level height and combining the amount of scrap steel added, the melting state of scrap steel can be judged. When the liquid level is basically stable, it can be considered that all the scrap steel is melted.

[0003] However, due to the special environment of extremely high temperature inside the electric furnace, it is impossible to directly measure the liquid level height. In the prior art, many researchers determine the melting of scrap steel by learning and identifying the noise of the electric furnace. However, in actual application, there are many sound interference factors, and the recognition accuracy is low. The data provided by them has large errors, and the actual application effect is not good. Its noise recognition cannot accurately reflect the melting state of scrap steel. Some researchers also measure the steel liquid level in the electric furnace by infrared ranging method. However, due to the high smoke and dust in the production environment of the electric furnace, the effect of infrared ranging is greatly affected. In addition, the thickness of the slag layer on the surface of the electric furnace is unstable. Infrared ranging actually measures the height of the slag surface rather than the steel liquid level in the electric furnace. Therefore, it cannot accurately determine the melting state of scrap steel, and the installation position of the infrared equipment is difficult to determine. Installing it outside the electric furnace will affect the measurement accuracy, and installing it inside will cause equipment damage. Summary of the invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a new electric furnace and a method for determining the melting state of scrap steel in the furnace, so as to solve the problem that there is no quantitative evaluation method for the melting state of scrap steel in the electric furnace in the prior art, and the accuracy of determining the melting state of scrap steel by experience-based means such as electric furnace noise recognition is low.

[0005] The present invention provides a novel electric furnace, which comprises an electric furnace body and a consumable electrode control device;

[0006] The electric furnace main body comprises an electric furnace cover and an electric furnace body;

[0007] The consumable electrode control device comprises a conductive cross arm, a lifting column, a base and a consumable electrode;

[0008] The conductive cross arm is connected to the base through a lifting column, and the conductive cross arm can be lifted and lowered in the vertical direction. The consumable electrode is vertically arranged at one end of the conductive cross arm away from the column and corresponds to the position of the electric furnace body;

[0009] An encoder is provided at one end of the conductive cross arm close to the column, the encoder is connected to the base through a pull rope and can measure the height of the conductive cross arm in real time;

[0010] The electric furnace also includes a camera on the upper edge of the electric furnace cover and a camera on the lower edge of the electric furnace cover. The camera on the upper edge of the electric furnace cover is flush with the upper edge of the electric furnace cover, and the camera on the lower edge of the electric furnace cover is flush with the lower edge of the electric furnace cover. The camera on the upper edge of the electric furnace cover and the camera on the lower edge of the electric furnace cover are both arranged away from the electric furnace body.

[0011] Specifically, the number of the conductive cross arms, lifting columns, pull ropes, and encoders corresponds to the number of the consumable electrodes.

[0012] Specifically, there are three consumable electrodes, namely, an A-phase electrode, a B-phase electrode and a C-phase electrode; the number of the conductive cross arm, the lifting column, the pull rope and the encoder are all three, and they match the corresponding electrodes.

[0013] Specifically, the electric furnace is also provided with an electric furnace door camera, which is flush with the height of the electric furnace door of the electric furnace main body and is arranged away from the electric furnace body, and is used to observe the slag flow of the electric furnace.

[0014] Specifically, there is an observation gap or an observation window between the lower edge of the electric furnace cover and the electric furnace body, and the camera at the lower edge of the electric furnace cover observes the state inside the furnace through the observation gap or the observation window.

[0015] The present invention also provides a method for judging the melting state of scrap steel in a furnace, which is applicable to the electric furnace and specifically comprises the following steps:

[0016] S1: Control the consumable electrode to descend by means of a lifting column, and when the end of the consumable electrode reaches the upper edge of the furnace cover, it is calibrated as the zero point of the electrode height measured by the encoder;

[0017] S2: Record the electrode height data in real time according to the data measured by the encoder, and draw an electrode height data graph;

[0018] S3: judging the melting state of scrap steel in the furnace according to the trend of the electrode height data graph, the melting state is divided into: stage 0: electrode descending stage; stage 1: well drilling stage; stage 2: scrap steel main melting stage; stage 3: scrap steel melting-heating stage, thereby guiding the implementation of supporting processes.

[0019] Furthermore, step S1 also includes an electrode height calibration operation: when the camera at the bottom edge of the electric furnace cover detects that the electrode end reaches the bottom edge of the electric furnace cover, the encoder reading L1 is read, and L1 is compared with the absolute height L of the furnace cover. When |L-L1|≤100mm, it indicates that the encoder reading is accurate.

[0020] Further, the electrode height data graph includes an A-phase electrode height graph, a B-phase electrode height graph, and a C-phase electrode height graph;

[0021] When performing step S3, if the height trend of a certain time period of one phase electrode is significantly different from that of the other two phases, the data of the corresponding time period of the phase electrode is discarded, and only the data of the two phase electrodes with similar trends are considered.

[0022] Specifically, the judgment criteria for each stage in step S3 are:

[0023] Wherein, on the electrode height curve, the electrode height data is segmented according to 1-min intervals, and each minute is divided into 6 10-s subintervals, the difference between L-max and L-min in each 10-s interval is △L, that is, the six subintervals corresponding to the nth minute are △Ln-1, △Ln-2, ​​△Ln-3, △Ln-4, △Ln-5, and △Ln-6, and the corresponding △Ln-average of the nth minute = (△Ln-1+△Ln-2+△Ln-3+△Ln-4+△Ln-5+△Ln-6) / 6, where n is a positive integer;

[0024] Stage 0: electrode descending stage, the time corresponding to the zero point of the electrode height is defined as T0, the time when the slope of the electrode height curve suddenly changes and an arc is generated at the end of the consumable electrode is defined as T1, and the stage corresponding to T0 to T1 is stage 0: electrode descending stage;

[0025] Stage 1: drilling stage. The starting point of stage 1 is time T1. The time when the electrode height curve changes from a smooth curve to a sawtooth curve and the slope suddenly changes is T2. The judgment basis is △Ln-average>50mm, then the starting time of the nth minute is defined as T2. The stage from T1 to T2 is stage 1: drilling stage.

[0026] Stage 2: main melting stage of scrap steel. The starting point of stage 2 is time T2. The time when the electrode height curve changes from a sawtooth curve to a smooth curve and the slope suddenly changes is T3. The judgment basis is △Ln-average ≤ 50mm. The starting time of the nth minute is defined as T3. The stage from T2 to T3 is stage 3: main melting stage of scrap steel.

[0027] Stage 3: scrap steel melting and heating stage. The starting point of stage 3 is time T3. From time T3, the electrode height curve becomes a smooth curve and enters stage 3: scrap steel melting and heating stage.

[0028] Preferably, the image recognition technology is used to analyze the image recorded by the electric furnace door camera, and the melting state of the scrap steel in the furnace is assisted in judging and verifying according to the slag flow situation of the electric furnace door.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] 1. The electric furnace provided by the present invention can monitor the height of each consumable electrode in real time. Combined with the matching method for judging the melting state of scrap steel in the furnace, it can quantitatively judge the melting state of scrap steel in the furnace, provide data support for adjusting the electric furnace smelting process parameters, and reduce production costs.

[0031] In view of the difficulty in directly measuring the molten steel level in the electric furnace, the present invention takes a different approach and indirectly determines the height of the molten steel level by measuring the position of the electrode. In view of the problem of electrode loss, the bottom position of the electrode is corrected and calibrated during the electrode lowering process at the beginning of each smelting to ensure the accuracy of the test results. In actual production, the consumable electrode adopts constant impedance control, so the distance between the end of the electrode and the liquid surface is basically stable, and even if there are small errors and delays, they are within an acceptable range. Based on the specific electrode height image and combined with the characteristics of different smelting stages, the present invention designs a complete set of judgment criteria and methods that can accurately judge the melting state of scrap steel in the furnace.

[0032] 2. The camera, encoder and other equipment of the present invention are all arranged at a position far away from the main body of the electric furnace, thereby avoiding the risk of damage due to high temperature and ensuring that the equipment can operate smoothly and safely.

[0033] 3. The equipment provided by the present invention is ingeniously conceived, simple in structure, not easy to damage, and suitable for application in production practice. At present, the new electric furnace of this style has begun field testing, and after actual inspection, it is found that the above method is used to judge the melting state of scrap steel in the furnace in actual production. Compared with the existing technology, the operability and accuracy are greatly improved, which can meet the needs of actual production.

[0034] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0036] Figure 1 It is a structural schematic diagram of a new type of electric furnace;

[0037] Figure 2 for Figure 1 DD direction view of the new electric furnace;

[0038] Figure 3 A schematic diagram of the camera setup for a new type of electric stove;

[0039] Figure 4 This is a curve diagram of the electrode height measured in Example 1;

[0040] Figure 5 (A) is a photograph of the end of the consumable electrode reaching the upper edge of the furnace cover in Example 1; (B) is a photograph of the end of the consumable electrode reaching the lower edge of the furnace cover in Example 1; (C) is a photograph of the slag flowing through the electric furnace door in Example 1.

[0041] Reference numerals:

[0042] 1. Electric furnace cover; 2. Electric furnace body; 3. Consumable electrode; 4. Conductive cross arm; 5. Lifting column; 6. Pull rope; 7. Encoder; 8. Base; 5A, A-phase electrode; 5B, B-phase electrode; 5C, C-phase electrode; 7A, Encoder A; 7B, Encoder B; 7C, Encoder C; 1-1, upper edge of electric furnace cover; 1-2, lower edge of electric furnace cover; 9, camera for upper edge of electric furnace cover; 10, camera for lower edge of electric furnace cover; 11, camera for electric furnace door; 12. Electric furnace door. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0044] The present invention provides a novel electric furnace, which comprises an electric furnace body and a consumable electrode control device;

[0045] The electric furnace main body comprises an electric furnace cover and an electric furnace body;

[0046] The consumable electrode control device comprises a conductive cross arm, a lifting column, a base and a consumable electrode;

[0047] The conductive cross arm is connected to the base through a lifting column, and the conductive cross arm can be lifted and lowered in the vertical direction. The consumable electrode is vertically arranged at one end of the conductive cross arm away from the column and corresponds to the position of the electric furnace body;

[0048] An encoder is provided at one end of the conductive cross arm close to the column, the encoder is connected to the base through a pull rope and can measure the height of the conductive cross arm in real time;

[0049] The electric furnace further comprises an upper edge camera of the electric furnace cover and a lower edge camera of the electric furnace cover, wherein the upper edge camera of the electric furnace cover is flush with the upper edge of the electric furnace cover, and the lower edge camera of the electric furnace cover is flush with the lower edge of the electric furnace cover, and the upper edge camera of the electric furnace cover and the lower edge camera of the electric furnace cover are both arranged away from the electric furnace body;

[0050] The camera at the upper edge of the electric furnace cover and the camera at the lower edge of the electric furnace cover are mainly used to detect the operating conditions of the end of the consumable electrode (mainly referring to the descending process).

[0051] Exemplarily, in actual implementation, the encoder and the pull rope can be combined into one component. In one possible design, the encoder and the pull rope can be designed to be a structure similar to an elastic tape measure. The pull rope part can rise and fall and extend and retract with the conductive cross arm / consumable electrode, and the encoder part can realize real-time monitoring of the electrode height by reading the scale on the pull rope.

[0052] It is worth noting that the electrode height can also be measured by other means, but taking into account the harsh conditions such as high temperature and smoke at the smelting site, the setting of encoder + pull rope can significantly reduce the equipment cost while ensuring the measurement effect, and because of its simple structure, it is not prone to failure and is suitable for large-scale and continuous production / smelting; preferably, a steel brush is provided at the connection between the encoder and the pull rope to effectively reduce dust from entering the encoder.

[0053] Specifically, constant impedance control is adopted during the lifting process of the conductive cross arm, and specific control parameters are selected and set according to actual needs with reference to relevant industry standards and operation manuals.

[0054] Furthermore, in actual implementation, the conductive cross arm synchronously drives the consumable electrode to move downward. When the single loss of the electrode is ignored, the height fluctuation of the conductive cross arm is basically the same as that of the consumable electrode. In addition, due to the constant impedance control, the electrode end and the steel liquid level remain basically stable from the start of arc discharge, and are not affected by the thickness of the slag layer. Therefore, the change of the steel liquid level can be indirectly reflected by the electrode height, and then the melting state of the scrap steel in the furnace can be judged.

[0055] Specifically, the number of the conductive cross arms, lifting columns, pull ropes, and encoders corresponds to the number of the consumable electrodes.

[0056] Specifically, there are three consumable electrodes, namely, A-phase electrode, B-phase electrode and C-phase electrode; the number of the conductive cross arm, lifting column, pull rope and encoder is three, and they match the corresponding electrodes. Since industrial electricity is three-phase electricity, the consumable electrodes are set to three, and the conductive cross arm, lifting column, pull rope, encoder and consumable electrode are set in a matching manner.

[0057] Preferably, the electric furnace is further provided with an electric furnace door camera, which is flush with the height of the electric furnace door of the electric furnace main body and is arranged away from the electric furnace body, and is used to observe the slag flow of the electric furnace.

[0058] Furthermore, the images collected by the electric furnace door camera can be analyzed in combination with an image recognition system or manually, and then the time when the electric furnace door starts to flow slag and the size of the flow slag can be analyzed, which can assist in judging the melting state of scrap steel in the electric furnace, and can also indirectly verify the accuracy of the judgment of the melting state of scrap steel in the electric furnace. Although the slag flow of the electric furnace cannot reflect the melting state of scrap steel in the furnace at each stage, when the furnace door starts to flow slag, it means that the electric furnace is mainly composed of molten steel, the electric furnace foam slag has been formed, and the molten pool in the electric furnace has been formed, which can assist in verifying the accuracy of the judgment method.

[0059] Specifically, there is an observation gap or observation window between the lower edge of the electric furnace cover and the electric furnace body, and the camera at the lower edge of the electric furnace cover observes the state inside the furnace through the observation gap or observation window. In a specific implementation, since the processing accuracy of the electric furnace body is not high, there is generally a certain gap between the electric furnace cover and the electric furnace body, and even if no observation gap or observation window is separately provided, the observation needs of the camera at the lower edge of the electric furnace cover can be met.

[0060] The present invention also provides a method for judging the melting state of scrap steel in a furnace, which is applicable to the novel electric furnace and specifically comprises the following steps:

[0061] S1: Control the consumable electrode to descend by means of a lifting column, and when the end of the consumable electrode reaches the upper edge of the furnace cover, it is calibrated as the zero point of the electrode height measured by the encoder;

[0062] S2: Record the electrode height data in real time according to the data measured by the encoder, and draw an electrode height data graph; measure the positions of all electrodes involved in power supply in real time to avoid errors caused by measuring a single electrode position, accurately measure the position of the electrode, and perform appropriate differentiation processing when drawing the electrode height data graph, such as processing the height data of one of the electrodes by +5mm or -5mm to avoid the height of each electrode overlapping when drawing the image, which is difficult to identify;

[0063] S3: judging the melting state of scrap steel in the furnace according to the trend of the electrode height data graph, the melting state is divided into: stage 0: electrode descending stage; stage 1: well drilling stage; stage 2: scrap steel main melting stage; stage 3: scrap steel melting-heating stage, thereby guiding the implementation of supporting processes.

[0064] Furthermore, after step S1, an electrode height calibration operation is also included: when the camera at the bottom edge of the furnace cover detects that the electrode end has reached the bottom edge of the furnace cover, the encoder reading L1 is read, and L1 is compared with the absolute height L of the furnace cover. When |L-L1|≤100mm, it indicates that the encoder reading is accurate. There are two main reasons why calibration is required for each furnace smelting. On the one hand, it avoids misjudgment caused by failure of the pull rope encoder. On the other hand, although the consumption of the consumable electrode in a single smelting process is basically negligible, after repeated use, the size and specifications of the consumable electrode will produce a large cumulative loss. Therefore, it is necessary to perform zero point (realized by the camera at the top edge of the furnace cover) and encoder calibration (realized by the camera at the bottom edge of the furnace cover) before each furnace smelting.

[0065] Further, the electrode height data graph includes an A-phase electrode height graph, a B-phase electrode height graph, and a C-phase electrode height graph;

[0066] When performing step S3, if the height trend of one phase electrode in a certain time period is significantly different from that of the other two phases, the data of the corresponding time period of the phase electrode is discarded, and only the data of the two phase electrodes with similar trends are considered. In actual production, due to the uneven stacking and composition of scrap steel, the melting is uneven, and finally the disturbance is generated in the descent process of individual consumable electrodes, such as slow descent or acceleration. Therefore, when judging the melting state of scrap steel in the furnace, the images of the three-phase electrodes should be comprehensively judged, and the data with significant deviations in individual time periods should be discarded to improve the credibility and accuracy of the judgment.

[0067] Specifically, the judgment criteria for each stage in step S3 are:

[0068] Wherein, on the electrode height curve, the electrode height data is segmented according to 1-min intervals, and each minute is divided into 6 10-s subintervals, the difference between L-max and L-min in each 10-s interval is △L, that is, the six subintervals corresponding to the nth minute are △Ln-1, △Ln-2, ​​△Ln-3, △Ln-4, △Ln-5, and △Ln-6, and the corresponding △Ln-average of the nth minute = (△Ln-1+△Ln-2+△Ln-3+△Ln-4+△Ln-5+△Ln-6) / 6, where n is a positive integer;

[0069] Stage 0: electrode descending stage, the time corresponding to the zero point of the electrode height is defined as T0, the time when the slope of the electrode height curve suddenly changes and an arc is generated at the end of the consumable electrode is defined as T1, and the stage corresponding to T0 to T1 is stage 0: electrode descending stage;

[0070] During stage 0, the consumable electrode descends at a uniform speed, and scrap steel smelting has not yet begun. It is reflected in the electrode height image as a smooth straight line / line segment with no disturbance and constant slope until arc discharge begins at the end of the consumable electrode;

[0071] Stage 1: drilling stage. The starting point of stage 1 is time T1. The time when the electrode height curve changes from a smooth curve to a sawtooth curve and the slope suddenly changes is T2. The judgment basis is △Ln-average>50mm, then the starting time of the nth minute is defined as T2. The stage from T1 to T2 is stage 1: drilling stage.

[0072] During stage 1, the electrode begins to discharge and melt the scrap steel, so the slope of the smooth straight line / curve of the electrode height image changes suddenly compared to stage 0, and the image appears slightly jagged; in this stage, the electrode continues to drop as the scrap steel melts, so the height of the electrode drop is obtained according to the pull-wire encoder. When the electrode reaches the molten pool position, it stops dropping and rises to a certain extent as the smelting process progresses, indicating that the drilling period is over;

[0073] Stage 2: main melting stage of scrap steel. The starting point of stage 2 is time T2. The time when the electrode height curve changes from a sawtooth curve to a smooth curve and the slope suddenly changes is T3. The judgment basis is △Ln-average ≤ 50mm. The starting time of the nth minute is defined as T3. The stage from T2 to T3 is stage 3: main melting stage of scrap steel.

[0074] During stage 2, the height between the electrode and the liquid level is relatively stable. At this time, due to the presence of a certain amount of unmelted scrap steel on the upper surface of the molten steel, the electrode has certain fluctuations when encountering scrap steel during the power supply process. This stage is the main melting period of scrap steel, which is reflected in the electrode height image. That is, with time T2 as the boundary, the slope of the curve changes again, but to a smaller extent, and the jagged feature of the curve is significantly prominent, corresponding to △Ln-average>50mm, until the electrode basically does not fluctuate violently, that is, △Ln-average≤50mm, corresponding to time T3, the scrap steel melting stage enters stage 3: scrap steel melting-heating stage.

[0075] Stage 3: Scrap steel melting and heating stage. The starting point of Stage 3 is time T3. From time T3, the electrode height curve becomes a smooth curve with a basically stable slope and the jagged feature almost disappears, entering Stage 3: Scrap steel melting and heating stage.

[0076] Specifically, when the electrode height images of at least two-phase electrodes within a certain period of time meet the above judgment criteria, it can be determined that the scrap steel in the furnace is in a corresponding melting state.

[0077] Preferably, the image recognition technology is used to analyze the image recorded by the electric furnace door camera, and the melting state of the scrap steel in the furnace is assisted in judging and verifying according to the slag flow situation of the electric furnace door.

[0078] Furthermore, the judgment method can be used to judge the overall melting state of the scrap steel based on the electrode height data / image, thereby obtaining the liquid level state during the electric furnace smelting process, which is helpful for understanding the changes in the refractory materials of the electric furnace; after obtaining the melting state of the scrap steel from this system and method, corresponding slag (dolomite, lime, etc.) can be added according to the melting state of the scrap steel, and the supporting process parameters can be adjusted in real time, which helps to improve production efficiency and smelting effect.

[0079] Example 1

[0080] Use Figure 1 The new type of electric furnace shown in the figure is used to melt scrap steel. After calibration, the electrode height data is measured and plotted as shown in the figure. Figure 4 shown.

[0081] The specific testing process is as follows:

[0082] S1: Control the consumable electrode to descend by means of a lifting column, and when the end of the consumable electrode reaches the upper edge of the furnace cover, it is calibrated as the zero point of the electrode height measured by the encoder;

[0083] S2: Record the electrode height data in real time according to the data measured by the encoder, and draw an electrode height data graph; measure the positions of all electrodes involved in power supply in real time, process the data of phase A electrode (electrode 1) by +5mm, and the data of phase B electrode (electrode 2) by -5mm;

[0084] S3: judging the melting state of scrap steel in the furnace according to the trend of the electrode height data graph, the melting state is divided into: stage 0: electrode descending stage; stage 1: well drilling stage; stage 2: scrap steel main melting stage; stage 3: scrap steel melting-heating stage, thereby guiding the implementation of supporting processes.

[0085] Furthermore, step S1 also includes an electrode height calibration operation: when the camera at the bottom edge of the electric furnace cover detects that the electrode end has reached the bottom edge of the electric furnace cover, the encoder reading L1 is read, and L1 is compared with the absolute height L of the furnace cover. When |L-L1|≤100mm, it indicates that the encoder reading is accurate, and the actual measured |L-L1|≈10mm meets the requirements.

[0086] The electrode height data graph includes the A-phase electrode height graph, the B-phase electrode height graph, and the C-phase electrode height graph; if the height trend of one phase electrode in a certain time period is significantly different from that of the other two phases, the data of the corresponding time period of the phase electrode is discarded, and only the data of the two phase electrodes with similar trends are considered. For example, when identifying the moment T1, since the height data of electrode 3 (C-phase electrode) is obviously disturbed, the moment T1 is identified by combining the arc generation time and the height curve images of electrodes 1 and 2, and the data selection for the subsequent identification of other moments is not repeated.

[0087] Wherein, on the electrode height curve, the electrode height data is segmented according to 1-min intervals, and each minute is divided into 6 10-s subintervals, the difference between L-max and L-min in each 10-s interval is △L, that is, the six subintervals corresponding to the nth minute are △Ln-1, △Ln-2, ​​△Ln-3, △Ln-4, △Ln-5, and △Ln-6, and the corresponding △Ln-average of the nth minute = (△Ln-1+△Ln-2+△Ln-3+△Ln-4+△Ln-5+△Ln-6) / 6, where n is a positive integer;

[0088] Stage 0: electrode descending stage, the time corresponding to the zero point of the electrode height is defined as T0, the time when the slope of the electrode height curve suddenly changes and an arc is generated at the end of the consumable electrode is defined as T1, and the stage corresponding to T0 to T1 is stage 0: electrode descending stage;

[0089] During stage 0, the consumable electrode descends at a uniform speed, and scrap steel smelting has not yet begun. It is reflected in the electrode height image as a smooth straight line / line segment with no disturbance and constant slope until arc discharge begins at the end of the consumable electrode;

[0090] Stage 1: drilling stage. The starting point of stage 1 is time T1. The time when the electrode height curve changes from a smooth curve to a sawtooth curve and the slope suddenly changes is T2. The judgment basis is △Ln-average>50mm, then the starting time of the nth minute is defined as T2. The stage from T1 to T2 is stage 1: drilling stage.

[0091] During stage 1, the electrode begins to discharge and melt the scrap steel, so the slope of the smooth straight line / curve of the electrode height image changes suddenly compared to stage 0, and the image appears slightly jagged; in this stage, the electrode continues to drop as the scrap steel melts, so the height of the electrode drop is obtained according to the pull-wire encoder. When the electrode reaches the molten pool position, it stops dropping and rises to a certain extent as the smelting process progresses, indicating that the drilling period is over;

[0092] Stage 2: main melting stage of scrap steel. The starting point of stage 2 is time T2. The time when the electrode height curve changes from a sawtooth curve to a smooth curve and the slope suddenly changes is T3. The judgment basis is △Ln-average ≤ 50mm. The starting time of the nth minute is defined as T3. The stage from T2 to T3 is stage 3: main melting stage of scrap steel.

[0093] During stage 2, the height between the electrode and the liquid level is relatively stable. At this time, due to the presence of a certain amount of unmelted scrap steel on the upper surface of the molten steel, the electrode has certain fluctuations when encountering scrap steel during the power supply process. This stage is the main melting period of scrap steel, which is reflected in the electrode height image. That is, with time T2 as the boundary, the slope of the curve changes again, but to a smaller extent, and the jagged feature of the curve is significantly prominent, corresponding to △Ln-average>50mm, until the electrode basically does not fluctuate violently, that is, △Ln-average≤50mm, corresponding to time T3, the scrap steel melting stage enters stage 3: scrap steel melting-heating stage.

[0094] Stage 3: Scrap steel melting and heating stage. The starting point of Stage 3 is time T3. From time T3, the electrode height curve becomes a smooth curve with a basically stable slope and the jagged feature almost disappears, entering Stage 3: Scrap steel melting and heating stage.

[0095] When the electrode is descending, an arc is generated when it approaches the scrap steel. Figure 4At time 1 (T1), the electrode has been in a downward trend since arcing began. At time 2 (T2) when the electrode has no obvious decline, the well penetration is completed. The period from time 1 (T1) to time 2 (T2) is the well penetration stage. This stage is mainly the electrode melting the scrap steel and thus penetrating the scrap steel layer. From time 2 (T2) onwards is the main melting stage of the scrap steel. From time 3 (T3), it indicates that the scrap steel melting enters the melting and heating stage, indicating that the scrap steel is basically completely melted. At this time, time 3 (T3) is defined as the end time of the scrap steel melting, and the scrap steel melting enters stage 3, namely the scrap steel melting and heating stage.

[0096] It can be seen from the above method that the overall melting state of the scrap steel can be judged by the change in the electrode height, thereby obtaining the liquid level state during the electric furnace smelting process, which is conducive to understanding the changes in the refractory materials of the electric furnace; after obtaining the melting state of the scrap steel through this judgment method, the corresponding slag (dolomite, lime, etc.) can be added according to the melting state of the scrap steel.

[0097] Furthermore, the furnace door camera can be used to obtain the moment when slag begins to flow from the furnace door. When the slag inside the furnace begins to flow out of the furnace door, it further indicates that the furnace is mainly composed of molten steel, foamy slag has been formed, and a molten pool has been formed in the furnace. The recognition by the furnace door camera further ensures the reliability and safety of the system.

[0098] Through indirect verification by on-site sampling, visual observation, furnace door slag flow, etc., the accuracy and immediacy of the judgment method can meet actual production needs, and the operability and accuracy are greatly improved compared with other existing technologies.

[0099] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A new type of electric furnace, characterized in that: The electric furnace comprises an electric furnace body and a consumable electrode (3) control device; The electric furnace body comprises an electric furnace cover (1) and an electric furnace body (2); The consumable electrode (3) control device comprises a conductive cross arm (4), a lifting column (5), a base (8) and a consumable electrode (3); The conductive cross arm (4) is connected to the base (8) via a lifting column (5), the conductive cross arm (4) can be lifted and lowered in a vertical direction, and the consumable electrode (3) is vertically arranged at one end of the conductive cross arm (4) away from the column and corresponding to the position of the electric furnace body (2); An encoder (7) is provided at one end of the conductive cross arm (4) close to the column, and the encoder (7) is connected to the base (8) via a pull rope (6) and is capable of measuring the height of the conductive cross arm (4) in real time; The electric furnace further comprises a camera (9) on the upper edge of the electric furnace cover and a camera (10) on the lower edge of the electric furnace cover. The camera (9) on the upper edge of the electric furnace cover is flush with the upper edge of the electric furnace cover (1). The camera (10) on the lower edge of the electric furnace cover is flush with the lower edge of the electric furnace cover (1). Both the camera (9) on the upper edge of the electric furnace cover and the camera (10) on the lower edge of the electric furnace cover are arranged away from the electric furnace body (2).

2. The electric furnace according to claim 1, characterized in that: The number of the conductive cross arms (4), lifting columns (5), pull ropes (6), and encoders (7) corresponds one-to-one to the number of the consumable electrodes (3).

3. The electric furnace according to claim 2, characterized in that: The number of the consumable electrodes (3) is three, namely, an A-phase electrode (5A), a B-phase electrode (5B) and a C-phase electrode (5C); the number of the conductive cross arm (4), the lifting column (5), the pull rope (6) and the encoder (7) is three, and they match the corresponding electrodes.

4. The electric furnace according to claim 1, characterized in that: The electric furnace is also provided with an electric furnace door camera (11). The electric furnace door camera (11) is flush with the height of the electric furnace door (12) of the electric furnace main body and is arranged away from the electric furnace body (2) for observing the slag flow of the electric furnace.

5. The electric furnace according to claim 1, characterized in that: There is an observation gap or an observation window between the lower edge of the electric furnace cover (1) and the electric furnace body (2), and the camera (10) at the lower edge of the electric furnace cover observes the state inside the furnace through the observation gap or the observation window.

6. A method for judging the melting state of scrap steel in a furnace, characterized in that: The judgment method is applicable to the electric furnace according to any one of claims 1 to 5, and specifically comprises the following steps: S1: controlling the consumable electrode (3) to descend by means of a lifting column (5), and calibrating the end of the consumable electrode (3) to the upper edge of the electric furnace cover (1) as the zero point of the electrode height measured by the encoder (7); S2: Recording the height data of the electrode in real time according to the data measured by the encoder (7), and drawing a graph of the electrode height data; S3: judging the melting state of scrap steel in the furnace according to the trend of the electrode height data graph, the melting state is divided into: stage 0: electrode descending stage; stage 1: well drilling stage; stage 2: scrap steel main melting stage; stage 3: scrap steel melting-heating stage, thereby guiding the implementation of supporting processes.

7. The determination method according to claim 6, characterized in that: The step S1 also includes an electrode height calibration operation: when the camera (10) at the bottom edge of the electric furnace cover detects that the electrode end has reached the bottom edge of the electric furnace cover (1), the encoder (7) reading L1 is read, and L1 is compared with the absolute height L of the cover. When |L-L1|≤100mm, it indicates that the encoder (7) reading is accurate.

8. The determination method according to claim 6, characterized in that: The electrode height data graph includes a height graph of an A-phase electrode (5A), a height graph of a B-phase electrode (5B), and a height graph of a C-phase electrode (5C); When performing step S3, if the height trend of a certain time period of one phase electrode is significantly different from that of the other two phases, the data of the corresponding time period of the phase electrode is discarded, and only the data of the two phase electrodes with similar trends are considered.

9. The determination method according to claim 6, characterized in that: The judgment criteria for each stage in step S3 are: Wherein, on the electrode height curve, the electrode height data is segmented according to 1-min intervals, and each minute is divided into 6 10-s subintervals, the difference between L-max and L-min in each 10-s interval is △L, that is, the six subintervals corresponding to the nth minute are △Ln-1, △Ln-2, ​​△Ln-3, △Ln-4, △Ln-5, and △Ln-6, and the corresponding △Ln-average of the nth minute = (△Ln-1+△Ln-2+△Ln-3+△Ln-4+△Ln-5+△Ln-6) / 6, where n is a positive integer; Stage 0: electrode descending stage, the time corresponding to the zero point of the electrode height is defined as T0, the time when the slope of the electrode height curve suddenly changes and an arc is generated at the end of the consumable electrode (3) is defined as T1, and the stage corresponding to T0 to T1 is stage 0: electrode descending stage; Stage 1: drilling stage. The starting point of stage 1 is time T1. The time when the electrode height curve changes from a smooth curve to a sawtooth curve and the slope suddenly changes is T2. The judgment basis is △Ln-average>50mm, then the starting time of the nth minute is defined as T2. The stage from T1 to T2 is stage 1: drilling stage. Stage 2: main melting stage of scrap steel. The starting point of stage 2 is time T2. The time when the electrode height curve changes from a sawtooth curve to a smooth curve and the slope suddenly changes is T3. The judgment basis is △Ln-average ≤ 50mm. The starting time of the nth minute is defined as T3. The stage from T2 to T3 is stage 3: main melting stage of scrap steel. Stage 3: scrap steel melting and heating stage. The starting point of stage 3 is time T3. From time T3, the electrode height curve becomes a smooth curve and enters stage 3: scrap steel melting and heating stage.

10. The determination method according to claim 6, characterized in that: The image recorded by the electric furnace door camera (11) is analyzed using image recognition technology, and the melting state of scrap steel in the furnace is assisted in judging and verifying according to the slag flow situation of the electric furnace door (12).

Images