Patent ID: 12247786

DETAILED DESCRIPTION

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.

Referring now toFIG.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 numeral100. The electrode monitoring system100includes a monitor102. The monitor102can be an electrode monitor for collecting and processing data related to electrode identification and monitoring. In other examples, the monitor102can be a furnace monitor102for collecting and processing operational data for an EAF shown generally at10. The EAF10can 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 EAF10uses electrodes, referred to generally at11, to melt metals and other ingredients to form steel. The electrodes11are joined together end-to-end to form electrode columns12,14,16, with each column powered by a 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 columns12,14,16and 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.

The furnace monitor102is 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 furnace10. The furnace monitor102is typically a local device, disposed onsite at the site of the EAF10. The electrode monitor and/or furnace monitor102includes a processor104, memory106and an input/output module108which are used for monitoring the electrodes12used in the furnace10, as described in further detail below.

An electrical meter110is operatively connected to the furnace monitor102, such as by an Ethernet connection112, for collecting electrical data pertaining to the furnace10. The electrical meter110can be an power meter, an ion meter, or other furnace monitoring device. The furnace monitor102collects the furnace electrical data from the electrical meter110on 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.

The system100further includes one or more programmable logic controllers (PLCs), only one of which is shown for simplicity at114. The one or more PLCs114are operatively connected to the furnace monitor102via the EAF owner's existing PLC network116, 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 PLCs114provide process information about each “heat,” to the furnace monitor102. The process data for each heat includes times, oxygen and natural gas consumption, process weights, temperatures and end-of-heat signals. The process data is another example of EAF data which is associated with electrode identifiers as described in further detail below.

A furnace monitor viewing system118is connected to the furnace monitor102via a wired or wireless local connection120for displaying the EAF data to users located onsite, i.e. at the EAF facility. The furnace monitor viewer system118can display the EAF data in real time during the operation of the EAF to assist furnace operators during furnace operation.

In at least one example, the system100can also include a remote server130located at a different location than the onsite furnace monitor102and connected to the furnace monitor via the Internet132. The remote server130includes a database133for storing the furnace data and processed data received from the furnace monitor102. The remote server130also includes a processor134configured 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 furnace10including operating trends, historical trends, statistical tables and graphical representations to better assist the viewer in evaluating the operation of the furnace10at it relates to specific electrodes, as described in further detail below. The remote server can include an Internet portal135for allowing authorized users to access the data described herein via the Internet. The remote server130can be a central server connected furnace monitors at several different EAF facilities. Alternatively, the remote server130can be dedicated to a single EAF facility.

In at least one example, the system100can also include a remote viewer136operatively connected to the furnace monitor102, the remote server130, or both via an internet connection132. The remote viewer136enables offsite technicians to view the furnace data and the current and past operating parameters described above.

The system100also includes an electrode detection and identification device150which detects an electrode and provides an electrode identifier to the furnace monitor. In at least one example, the device150includes a Radio Frequency Identification (RFID) tag reader152, also known as an interrogator, or reader, connected to one or more antennas154. The antennas154are disposed at a location156, such as the vicinity of the EAF furnace10, for capturing signals from RFID tags, referred to generally at29, which are attached to electrodes11that are located in that vicinity156.

Referring now toFIGS.2a&2b, an example graphite electrode discussed herein is shown generally at11. The graphite electrode11includes an electrode body20formed of graphite. The body20is generally cylindrical having oppositely disposed ends22and24which include threaded connectors. The threaded connectors can include a threaded socket26formed in one of the ends,22,24and a threaded pin28formed at the other of the ends. In one example the threaded pin28is formed integrally with the body20, such as by machining. The pin28includes a truncated conical threaded portion40extending from the body end24and terminating in an end face42. In another example, the pin28′ includes oppositely disposed truncated conical threaded portions40′ each terminating in oppositely disposed end faces42. In this example the pin28′ is threaded into a socket26of an electrode which has a socket at each end22and24to form a pin disposed at one of the ends22,24.

The threaded pin28,28′ and threaded socket26are of matching size and shape so that the threaded pin28of one electrode11acan be received in the threaded socket26of another electrode11bto join the electrodes together at a joint29to form an electrode column shown generally at30inFIG.2b. As discussed above, when in use in the EAF, a separate electrode column30is used for each phase of a multi-phase furnace. Thus, for example, the 3 phase AC EAF10shown inFIG.1utilizes 3 electrode columns12,14,16, each corresponding to a different electrical phase of the 3 phase EAF.

The electrode11includes at least one tag29attached to the body, wherein the tag creates a non-line-of-sight signal representing an electrode identifier. The tag29can be an RFID tag. The RFID tag29can be a passive tag having a non-powered signal generator configured to transmit a signal to the antenna154described above. Alternatively, the RFID tag29can be an active tag having a powered signal generator configured to transmit a signal to the antenna154. 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 or 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.

The electrode11can include one RFID tag29attached to the body20. Examples of this arrangement include the one tag attached to the pin28, or to a different location at the end24, or to the socket26or to a different location at the end22, or to body20disposed between the ends22,24. The electrode11can include two RFID tags29. In one example the two tags29are configured to transmit the same signal to the antenna154corresponding to the same electrode identifier. In another example, the two tags29′,29″ are configured to transmit the different signals to the antenna154corresponding to the same electrode identifier. The RFID tags will be referred to generally as RFID tag29, or tag29. A collection of RFID tags, each corresponding to a different electrode identifier, will be designated as29a,29b. . .29n, for example29a,29b, and29cfor 3 tags corresponding to 3 different electrode identifiers.

As mentioned above, and referring again toFIG.1, the antennas154are disposed at a location156for capturing signals from the RFID tags29which are attached to electrodes11in that location. In one or more examples, the location is the vicinity of an EAF. In other examples, the location156is in the vicinity of an electrode adding station. In another example the location is in the vicinity of a tilt table158where 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 EAF10. In other examples the vicinity is within 1 to 50 feet of the EAF10, and in still another example the vicinity is within 1 to 20 feet of the EAF.

The RFID tag reader152includes a processor160configured for receiving signals from the at least one antenna154and converting the signals to electrode identifiers. The RFID tag reader152also includes memory162for storing a set of the electrode identifiers corresponding to the electrodes11a,11band11cat a location156, such as for example in the vicinity of the EAF10. The reader152periodically reads the tags29a,29b,29cattached to the electrodes11a,11b,11cat the location156and populates the memory registers162with the electrodes' corresponding electrode identifiers.

The tag reader152is connected to the furnace monitor102by a connection164, such as by an Ethernet connection. The furnace monitor processor104is configured for receiving the set of electrode identifiers stored in the tag reader memory162, associating the electrode identifiers with the EAF data corresponding to the specific EAF10in which the electrode was used, and storing the association in the EAF monitor memory106. Examples of the EAF data include the electrical data obtained by the electrical meter110described above, the process data obtained by the one or more PLCs described above, or combinations of both.

The furnace monitor processor104can 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 system118during the operation of the EAF10to assist furnace operators and technicians during furnace operation.

The furnace monitor processor104can also be configured to process the EAF data for specific electrodes to generate current and past operating parameters of the electric arc furnace10for, 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 furnace10. The processor104can be configured to generate reports and transmit the reports to the local viewer118, 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 all be associated or correlated with specific electrodes by using the electrode identifiers described above.

Alternatively, or in addition to the local processing and displaying of the association of the electrode identifier and EAF data described above, the furnace monitor102can process portions of the EAF data and send the processed EAF data and unprocessed EAF data via the Internet132to the remote central server130disposed at a different location from the monitor102for storage in the database133. The remote server130includes a processor134configured to use the 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 the remote viewer system136during the operation of the EAF10to assist furnace operators during furnace operation.

The server processor134can 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 furnace10for, 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 portal135to better assist the viewer in evaluating the operation of the furnace10. 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.

Other examples of the EAF data can include, but is not limited to, a time or time period, that the electrode was detected at the location156, such as the EAF vicinity, and/or the time or time period that an electrode which was previously detected at the location156was no longer detected at that location. The furnace monitor processor104can be configured to receive this EAF data from the tag reader152by periodically reading the tag reader memory162.

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.

A method of determining that an electrode is added to an electrode column includes: Monitoring RFID tags at a location within range of the antennas154; receiving electrode identifiers from an RFID tag reader corresponding to the signals received from the RFID tags attached to electrodes disposed at the location156; placing electrode identifiers in memory registers within the RFID reader no less than every N minutes, wherein 0.01<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.

With reference again toFIG.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 furnace10. In one embodiment, the first monitored operating parameter is the movement of the electrode mast50, by a column position transducer or a pressure transducer. Also the position of the clamp52can be monitored. The electrode column12,14, or16associated with the clamp52which moves after the missing electrode is detected is determined to be the column12,14,16receiving 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.

Thus, according to the above, a control signal may directly indicate the electrode column which receives the added electrode. The furnace monitor processor104is configured to associate the electrode identifier with the electrode column12,14,16and store this association in memory106. This association can be transferred to remote server130for storage in database133and further processing by processor134to generate the current and past operating parameters and reports discussed above.

The operation of the electrode monitoring system100includes 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 location156, 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 location156, and storing the electrode identifier in memory. The tag reader reads the electrode tags in this manner for each of the electrodes located at location156and stores the electrode identifiers as sets of identifiers in the reader's memory.

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 server130via an internet connection. The EAF server processor134associates the electrode identifiers with specific furnace heats for which the electrodes were used for tracking the operation of the electrode while it is used in the EAF10.

A method for monitoring the graphite electrodes for the electric arc furnace10generally 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.

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.

The furnace monitoring system100uses 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.

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

The above description is intended to enable the person skilled 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.