IDENTIFICATION AND MONITORING

BACKGROUND

[0001] The present invention relates to graphite electrodes lor elect 15ric arc furnaces (EAFs) and more specifically, to an electrode identification and monitoring system and method that automatically provides electrode identification data for use in improving the operation of the electric arc furnace.

[0002] An electric arc furnace heats a charge of steel scrap materia) by means of an electric arc. The charged material is melted by direct exposure to the electric arc and subsequent passing of the electric current therethrough. An electric arc furnace generally includes a large vessel, covered with a retractable roof. The roof includes holes that allow one (in a DC furnace) or more commonly three (in an AC furnace) graphite electrode columns to enter the furnace. A movable electrode support structure holds and moves the electrode columns to maintain proximity to the scrap material. Power for the electrode columns is provided by a transformer, typically located near the furnace. The electrode columns each include a plurality of individual electrodes that are secured together with threaded connections at each end. The electrodes are slowly consumed as part of the steel making process and thus, new electrodes must be added to each column periodically.

[0003] During the melting cycle, referred to as a "heat", a power regulating system attempts to maintain approximately constant current, power, impedance, admittance, resistance or some combination of these inputs during the melting of the charge. The regulator therefore seel® to control the distance between the electrode tip and the burden (solid change material or molten metal) given the adopted regulation philosophy. This is made more difficult when scrap moves under the electrodes as it melts. Input is regulated, in part, by employing ah electrode positioning system which automatically raises arid lowers the electrode columns. In most cases, positioning systems may employ hydraulic cylinders to provide the moving force. Once relatively steady state conditions are reached in the furnace, (i.e. the scrap is substantially melted) another bucket of scrap may be charged into the furnace and melted down. After the first or optional second charge is completely melted, various other operations take place such as, refining, monitoring chemical compositions, and finally superheating the melt in preparation for tapping.

[0004] The graphite electrodes' chemical composition can be varied somewhat by the manufacturer to optimize performance characteristics. Determining electrode performance in the EAF requires knowledge of which specific electrodes are being used in each heat It is desirable to obtain this information in an accurate and automated manner.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The structure and preferred embodiments of the invention can best be understood by reference to the accompanying drawings, in which:

[0006] Fig. 1 is a block diagram illustrating a system for detecting and monitoring a graphite electrode in the vicinity of an electric arc furnace, in accordance with the present invention;

[0007] Fig. 2a illustrates an electrode having at least one RFID tag attached for detection and monitoring by the system of Fig. 1 ; and [0008] Fig. 2b illustrates an electrode column having plurality of electrodes connected together for use in the electric arc furnace of Fig. 1.

DETAILED DESCRIPTION

[0009] Graphite electrodes are a necessary consumable in an electric arc furnace and are the only known material suitable to withstand the extremely harsh operating environment of the electric furnace steelmaking operation. Accordingly, steel manufacturers are highly cognizant of the cost and performance of the graphite electrodes being consumed in the furnace. The systems and methods disclosed herein for monitoring electrodes used in an electric arc furnace can be used to monitor and improve the performance of graphite electrodes.

[0010] Referring now to Fig. 1, a system for monitoring electrodes used in an electric arc furnace (EAF) constructed in accordance with the present invention is shown generally by reference numeral 100; The electrode monitoring system 100 includes a monitor 102, The monitor 102 can be an electrode monitor for collecting and processing data related to electrode identification and monitoring. In other examples, the monitor 102 can be a furnace monitor 102 for collecting and processing operational data for an EAF shown generally at 10. The EAF 10 can be an AC furnace, of a 3 phase design having an electrode column for each phase, or a DC furnace consisting of one or two electrode columns. A 3 phase EAF AC furnace is described herein by way of example. The EAF 10 uses electrodes, referred to generally at 11, to melt metals and other ingredients to form steel. The electrodes 11 are joined together end-to-end to form electrode columns 12, 14, 16, with each column powered by e separate electrical phase (In 3 phase AC furnaces). DC furnaces employ a single column (i.e. cathode), or two columns (i.e. anode and cathode). The heat needed to melt metals is generated by passing current through the one or more of the electrode columns 12, 14, 16 and forming an arc between the electrode column(s) and the metal in the furnace. Electrical currents in excess of 100,000 amperes are often used. The resulting high temperature melts the metals and other ingredients in an heating operation known as a "heat", further details of which are provided below.

[0011] The furnace monitor 102 is a computer control device, such as for example a modular controller, configured to receive a wide range of data regarding of the operation of the furnace 10. The furnace monitor 102 is typically a local device, disposed onsite at the site of the EAF 10. The electrode monitor and/or furnace monitor 102 includes a processor 104, memory 106 and an input/output module 108 which are used for monitoring the electrodes 12 used in the furnace 10, as described in further detail below.

[0012] An electrical meter 110 is operatively connected to the furnace monitor 102, such as by an Ethernet connection 112, for collecting electrical data pertaining to the furnace 10. The electrical meter 110 can be an power meter, an ion meter, or other furnace monitoring device. The furnace monitor 102 collects the furnace electrical data from me electrical meter 110 on a periodic basis. The collected data includes voltage and current measurements generated from the current and voltage transformers connected to each phase of the primary electrical circuit. The furnace electrical data is an example of EAF data which is associated with specific electrodes using electrode identifiers as described in further detail below. [0013] The system 100 further includes one or more programmable logic controllers (PLCs), only one of which is shown for simplicity at 114. The one or more PLCs 114 are operatively connected to the furnace monitor 102 via the EAF owner's existing PLC network 116, examples of which can include an Ethernet connection and/or a serial connection such as for example an RS242, RS422 or RS485 connection. The one or more PLCs 114 provide process information about each "heat," to the furnace monitor 102. The process data for each heat includes times, oxygen and natural gas consumption, process weights, temperatures and endof-heat signals. The process data is another example of EAF data which is associated with electrode identifiers as described in further detail below.

[0014] A furnace monitor viewing system 118 is connected to the furnace monitor 102 via a wired or wireless local connection 120 for displaying the EAF data to users located onstte, i.e. at the EAF facility. The furnace monitor viewer system 118 can display the EAF data in real time during the operation of the EAF to assist furnace operators during furnace operation.

[001$] In at least one example, the system 100 can also include a remote server 130 located at a different location than the onsite furnace monitor 102 and connected to the furnace monitor via the Internet 132. The remote server 130 includes a database 133 for storing the furnace data and processed data received from the furnace monitor 102. The remote server 130 also includes a processor 134 configured to further process the EAF data in association with electrode identifiers Identifying specific electrodes to allow a user to view current and past operating parameters of the electric arc furnace 10 including operating trends, historical trends, statistical tables and graphical representations to better assist the viewer in evaluating the operation of the furnace 10 at it relates to specific electrodes, as described in further detail below. The remote server can include an internet portal 135 for allowing authorized users to access the data described herein via the Internet The remote server 130 can be a central server connected furnace monitors at several different EAF facilities. Alternatively, the remote server 130 can be dedicated to a single EAF facility.

[0016] In at least one example, the system 100 can also include a remote viewer 136 operatively connected to the furnace monitor 102, the remote server 130, or both via an internet connection 132. The remote viewer 136 enables offstte technicians to view the furnace data and die current and past operating parameters described above.

[0017] The system 100 also includes an electrode detection and identification device 150 which detects an electrode and provides an electrode identifier to the furnace monitor. In at least one example, the device 150 includes a Radio Frequency Identification (RFID) tag reader 152, also known as an interrogator, or reader _* connected to one or more antennas 154. The antennas 154 are disposed at a location 156, such as the vicinity of the EAF furnace 10, for capturing signals from RFID tags, referred to generally at 29, which are attached to electrodes 11 that are located in that vicinity 156.

[0018] Referring now to Figs. 2a & 2b, an example graphite electrode discussed herein Is shown generally at 11. The graphite electrode 11 1ncludes an electrode body 20 formed of graphite. The body 20 is generally cylindrical having oppositely disposed ends 22 and 24 which include threaded connectors. The threaded connectors can include a threaded socket 26 formed in one of the ends, 22, 24 and a threaded pin 28 formed at the otiier of tiie ends. In one example the threaded pin 28 is formed integrally with the body 20, such as by machining. The pin 28 includes a truncated conical threaded portion 40 extending from the body end 24 and terminating in an end face 42. in another example, the pin 28' Includes oppositely disposed truncated conical threaded portions 40' each terminating in oppositely disposed end faces 42. In this example the pin 28' is threaded into a socket 26 of an electrode which has a socket at each end 22 and 24 to form a pin disposed at one of the ends 22, 24.

[0019] The threaded pin 28, 28' and threaded socket 26 are of matching size and shape so that tie threaded pin 28 of one electrode 11a can be received in the threaded socket 26 of another electrode 11b to join the electrodes together at a joint 29 to form an electrode column shown generally at 30 in Fig. 2b. As discussed above, when in use in the EAF, a separate electrode column 30 is used for each phase of a multi-phase furnace. Thus, for example, the 3 phase AC EAF 10 shown in Fig. 1 utilizes 3 electrode columns 12, 14, 16, each corresponding to a different electrical phase of the 3 phase EAF.

[0020] The electrode 11 includes at least one tag 29 attached to the body, wherein the tag creates a non-line-of-sight signal representing an electrode identifier. The tag 29 can be an RFID tag. The RFID fag 29 can be a passive tag having a non-powered signal generator configured to transmit a signal to the antenna 154 described above. Alternatively, the RFID tag 29 can be an active tag having a powered signal generator configured to transmit a signal to the antenna 154. in each instance, the signal corresponds to an electrode identifier. The electrode identifier uniquely identifies a single, specific electrode. The electrode identifier can include electrode data corresponding to the specific electrode which it identifies. Examples of this electrode data can include some of all of, but is not limited to, an identifier identifying the location of the plant at which the electrode was machined, an identifier identifying the line on which the electrode was machined, a weight of the electrode, a date the electrode was machined, a sequential number for identifying a specific electrode within a sequence of numbers identifying a set of electrodes. An electrode identifier including this combination of electrode data can be referred to as a Base of Socket identifier. The electrode identifier can also include batch identification information identifying the batch from which the graphite electrode was formed. The electrode identifier can include an EAF owner-specific electrode identifier, also known as a stencil number, for identifying the specific electrode using criteria provided by the EAF owner.

[0021] The electrode 11 can include one RFID tag 29 attached to the body 20. Examples of this arrangement include the one tag attached to the pin 28, or to a different location at the end 24, or to the socket 26 or to a different location at the end 22, or to body 20 disposed between the ends 22, 24. The electrode 11 can include two RFID tags 29. in one example the two tags 29 are configured to transmit the same signal to the antenna 154 corresponding to the same electrode identifier, in another example, the two tags 29', 29" are configured to transmit the different signals to the antenna 154 corresponding to the same electrode identifier. The RFID tags will be referred to generally as RFID tag 29, or tag 29. A collection of RFID tags, each corresponding to a different electrode identifier, will be designated as 29a, 29b...29n, for example 29a, 29b, and 29c for 3 tags corresponding to 3 different electrode identifiers.

[0022] As mentioned above, and referring again to Fig. 1, the antennas 154 are disposed at a location 156 for capturing signals from the RFID tags 29 which are attached to electrodes 11 in that location. In one or more examples, the location is the vicinity of an EAF. in other examples, the location 156 is in the vicinity of an electrode adding station. In another example the location is in the vicinity of a tilt table 158 where electrodes are moved from a horizontal orientation to a vertical orientation when being added to an electrode column, in other examples, the location is a vicinity within 1 to 100 feet from the EAF 10. In other examples the vicinity is within 1 to 50 feet of the EAF 10, and in still another example the vicinity is within 1 to 20 feet of the EAF.

[0023] The RFID tag reader 152 includes a processor 160 configured for receiving signals from the at least one antenna 154 and converting the signals to electrode identifiers. The RFID tag reader 152 also includes memory 162 for storing a set of the electrode identifiers corresponding to the electrodes 11a, 11b and 11c at a location 156, such as for example in the vicinity of the EAF 10. The reader 152 periodically reads the tags 29a, 29b, 29c attached to the electrodes 11a, 11b, 11c at the location 156 and populates the memory registers 162 with the electrodes' corresponding electrode identifiers.

[0024] The tag reader 152 is connected to the furnace monitor 102 by a connection 164, such as by an Ethernet connection. The furnace monitor processor 104 is configured for receiving the set of electrode identifiers stored in the tag reader memory 162, associating the electrode identifiers with the EAF data corresponding to the specific EAF 10 in which the electrode was used, and storing the association in the EAF monitor memory 106. Examples of the EAF data include the electrical data obtained by the electrical meter 110 described above, the process data obtained by the one or more PLCs described above, or combinations of both. [0025] The furnace monitor processor 104 can be configured to use the association of the electrode identifier and EAF data described above to generate EAF data for specific electrodes and display this information on the local viewer system 118 during the operation of the EAF 10 to assist furnace operators and technicians during furnace operation.

[0026] The furnace monitor processor 104 can also be configured to process the EAF data for specific electrodes to generate current and past operating parameters of the electric arc furnace 10 for, or in relation to, specific electrodes including operating trends, historical trends, statistical tables and graphical representations, heat analysis reports, correlations and other analyses to better assist the viewer in evaluating the operation of the furnace 10. The processor 104 can be configured to generate reports and transmit the reports to the local viewer 118, the reports detailing the historical operation of the furnace in relation to specific electrodes using the association of the electrode identifier and EAF data described above. These reports include, for example, a single heat summary which includes the electrodes used in the heat, a daily heat summary which includes the electrodes used in all of the day's heats, daily shift heat summary and pertaining electrodes, weekly heat summary and pertaining electrodes, monthly heat summary and pertaining electrodes, heat summary by date range and conditions and pertaining electrodes, performance reporting in graphical format for pertaining electrodes, refractory wear reporting includes electrodes used, event log reporting pertaining to specific electrodes, specific electrode consumption reporting, and specific electrode usage and specific inventory reporting. These reports can now ail be associated or correlated with specific electrodes by using the electrode identifiers described above. [0027] Alternatively, or in addition to the local processing and displaying of the association of the electrode identifier and EAF data described above, the furnace monitor 102 can process portions of the EAF data and send the processed EAF data and unprocessed EAF data via the Internet 132 to the remote central server 130 disposed at a different location from the monitor 102 for storage in the database 133. The remote server 130 includes a processor 134 configured to use Hie association of the electrode identifier and EAF data described above and/or to make the association of the electrode identifier and EAF data described above to generate EAF data for specific electrodes, and/or indicate specific electrodes associated with particular EAF data, display this information on Hie remote viewer system 136 during the operation of the EAF 10 to assist furnace operators during furnace operation.

[0028] The server processor 134 can also be configured to process the EAF data for specific electrodes to allow a user to view current and past operating parameters of the electric arc furnace 10 for, or in relation to, specific electrodes including operating trends, historical trends, statistical tables and graphical representations, heat analysis reports, correlations and other analyses via the Internet portal 135 to better assist the viewer in evaluating the operation of the furnace 10. Authorized users may view reports via the portal detailing the historical operation of the furnace in relation to specific electrodes using the association of the electrode identifier and EAF data described above. These reports include, for example, a single heat summary, a daily heat summary, daily shift heat summary, weekly heat summary, monthly heat summary, heat summary by date range and conditions, performance reporting in graphical format refractory wear reporting, event log reporting, electrode consumption reporting, and electrode usage and inventory reporting all for (i.e. in relation to) specific electrodes.

[0029] Other examples of the EAF data cart include, but is not limited to, a time or time period, that the electrode was detected at the location 156, such as the EAF vicinity, and/or the time or time period that an electrode which was previously detected at the location 156 was no longer detected at that location. The furnace monitor processor 104 can be configured to receive this EAF data from the tag reader 152 by periodically reading the tag reader memory 162.

[0030] Determining the number of heats/add requires first knowing when an electrode is added to each electrode column and/or how many are added over the subject period of time. As discussed above, the determination that an electrode is added to one or more of the electrode columns Is advantageously performed automatically.

[0031] A method of determining that an electrode is added to an electrode column includes: Monitoring RFIO tags at a location within range of the antennas 154;. receiving electrode identifiers from an RFID tag reader corresponding to the signals received from the RFID tags attached to electrodes disposed at the location 156; placing electrode identifiers in memory registers within the RFID reader no less than every N minutes, wherein .01<N<100; an electrode monitor reading the RFID reader memory and determining that an RFID identifier which was read previously is now no longer read from the memory thereby identifying that RFID identifier as a missing electrode identifier; associating the missing electrode identifier with an electrode column using electrode clamp data and/or electrode mast data. [0032] With reference again to Fig. 1, the method for associating the missing electrode identifier with an electrode column using electrode clamp data and/or electrode mast data can include monitoring two operating parameters of the electric arc furnace i 0. In one embodiment, the first monitored operating parameter is the movement of the electrode mast 50, by a column position transducer or a pressure transducer. Also the position of the damp 52 can be monitored. The electrode column 12, 14, or 16 associated with the damp 52 which moves after the missing electrode is detected is determined to be the column 12, 14, 16 receiving the missing electrode identified and determined to be the added electrode. The method can further include determining the electrical phase of the EAF associated with the electrode column which receives the added electrode and associating the electrode identifier with that electrical phase.

[0033] Thus, according to the above, a control signal may directly Indicate the electrode column which receives the added electrode. The furnace monitor processor 104 is configured to associate the electrode identifier with the electrode column 12, 14, 16 and store this association in memory 10$. This association can be transferred to remote server 130 for storage in database 133 and further processing by processor 134 to generate the current and past operating parameters and reports discussed above,

[0034] The operation of the electrode monitoring system 100 includes the tag reader capturing signals from the RFID tags attached to each of the graphite electrodes using one or more of the antennas which are disposed at a location 156, such as for example the vicinity of the EAF; the tag reader converting the signals into an electrode identifier specifically identifying the graphite electrode located at the location 156, and storing the electrode identifier in memory. The tag reader reads the electrode tags in this manner for each of the electrodes located at location 156 and stores the electrode identifiers as sets of identifiers in tie reader's memory.

[0035] The electrode monitor controller periodically reads the tag reader memory to obtain the set of electrode identifiers and sends the set to the EAF monitoring server 130 via an internet connection. The EAF server processor 134 associates the electrode identifiers with specific furnace heats tor which the electrodes were used for tracking the operation of the electrode while it is used in the EAF 10.

[0036] A method for monitoring the graphite electrodes for the electric arc furnace 16 generally comprises: capturing a signal from a tag, such as a radio frequency identification (RFID) tag, attached to a graphite electrode; converting the signal into an electrode identifier identifying the graphite electrode; transmitting the electrode identifier to an electric arc furnace monitor; receiving a set of electrode identifiers from an electrode tag reader at the monitor, the electrode identifiers obtained from signals from radio frequency identification (RFID) tags attached to graphite electrodes disposed near the location of the antenna, such as for example in the vicinity of the EAF; associating the electrode identifiers with EAF data corresponding to the specific electrodes; and storing the association in the EAF monitor memory.

[0044] The systems and methods of electrode identification described herein allow EAF operators and service personnel to determine which specific electrodes are used in each particular heat. Knowing the specific electrodes which are used in a heat enables operators and service personnel to correlate electrode performance with electrode batches thereby improving the performance of the graphite electrodes and/or EAF. [0045] The furnace monitoring system 10 uses state of the art hardware and software to record the full range of operational parameters, including chemical ones, which make up the total operating environment of the electric arc furnace. The present invention provides on-line, real time access to the EAF data correlated to specific electrodes using the electrode identifiers detected and monitored as described herein.

[0046] The disclosures of all cited patents and publications referred to in this application are incorporated herein by reference.

[0047] The above description is intended to enable the person stalled in the art to practice the invention, it is not intended to detail all of the possible variations and modifications that will become apparent to the skilled worker upon reading the description. It is intended, however, that all such modifications and variations be included within the scope of the invention that is defined by the following claims. The claims are intended to cover the indicated elements and steps in any arrangement or sequence that is effective to meet the objectives intended for the invention, unless the context specifically indicates the contrary.