Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21B—MANUFACTURE OF IRON OR STEEL
  • C21B7/00—Blast furnaces
  • C21B7/04—Blast furnaces with special refractories
  • C21B7/06—Linings for furnaces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/12—Shells or casings; Supports therefor
  • F27B1/14—Arrangements of linings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/16—Arrangements of tuyeres
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B1/00—Shaft or like vertical or substantially vertical furnaces
  • F27B1/10—Details, accessories or equipment specially adapted for furnaces of these types
  • F27B1/28—Arrangements of monitoring devices, of indicators, of alarm devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D21/00—Arrangement of monitoring devices; Arrangement of safety devices
  • F27D21/0021—Devices for monitoring linings for wear
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
  • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
  • G01B21/08—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness
  • G01B21/085—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness for measuring thickness using thermal means

Definitions

• the present invention particularly, relates to a method and a system for providing estimates and knowledge/status of the condition of the refractories in the hearth region, particularly the left out lining thickness in a blast furnace.
• the method also determines the temporary protective skull layer thickness over the remnant refractory.
• the present invention is applicable to running Blast Furnaces in the later stages of their operating life. In case the estimate shows a dangerously thin refractory layer remaining in a specific location, it alerts the operators to take remedial action by directing repairs of the refractories at the relevant areas, to improve cooling arrangements to withdraw heat fluxes, or to close specific tuyeres to run the Blast Furnace at reduced capacity. Failing these, this method informs the management that the time has come to shut down the Blast Furnace for relining the refractory layers.
• Dead Man Zone A body of coke at the base of the hearth Ramming mass: A refractory mix used to fill gaps 2D/3D: 2Dimensional/ 3Dimensional
• Hot metal The metal produced in Blast Furnaces. Iron with 4%C, at 1450 DegC.
• Hearth The base of the Blast Furnace holding hot metal formed with refractory material. Subject to severe thermal and abrasive wear conditions.
• Taphole An opening through which the hot metal (liquid iron) is extracted.
• Shell Cylindrical steel lining, which forms a container for the Blast Furnace.
• Skull A hard growth of refractory material and charge ore, on the lining.
• RMS Root Mean Square of the deviation between calculated and measured values
• DegC Degrees Centigrade 1 150
• DegC solidus line A temperature contour at 1 150 DegC, considered to be the solidification location of liquid iron (iron-carbon solidus). Also, considered as the refractory boundary.
• Forward refers to the standard FE technique, where the thermal properties are used to solve for the temperature field.
• Inverse refers to the estimated values of the thermal properties that result in a temperature field that best matches measurements at a few specified locations.
• Blast Furnaces are the primary route through which iron is produced. It is a counter current reactor, comprising a vertical steel shell lined internally with refractories. A preheated hot blast of air is forced into the base, hence the name "Blast Furnace”. Raw material as Iron ore together with fuel in the form of coke and fluxes as limestone are charged from the top. Complex reactions in the solid liquid and gas phases occur, with temperatures in the region of 2000 DegC. Liquid iron known as Hot metal drips down in the lower third of the furnace at a temperature of 1450 DegC, and collects in the lower region known as the Hearth, from where it is tapped out through openings called "Tapholes".
• thermocouples into the refractories at the time that the brick courses are laid when building the new Blast Furnace. These temperature sensors are laid out circumferentially at incremental heights according to a carefully planned strategy, dictated by prior experience as to the regions of greatest wear.
• 1 150 DegC is the temperature at which liquid iron solidifies, and can be considered to be the refractory boundary. The common practice is to derive the remnant refractory thickness based on a linear interpolation of the temperature drop in a pair of in-line thermocouples.
• the iron solidifies at 1 150 DegC, and this temperature is considered to define the interface between the liquid iron and the solid refractory which serves to hold the Hot metal.
• the liquid Hot metal must not touch the steel shell of the Blast Furnace, where it would melt and pierce the structure, and lead to fatal accidents. This is known as a "Break out", and is a major concern in the iron making process.
• thermocouples are embedded in the refractories at insertion depths of 100 mm, and the temperatures are watched for sudden & unexplained increases.
• a linear interpolation from dual inline thermocouples is sometimes used to obtain the 1 150 DegC solidus line.
• the Finite Element Analysis is an established method of calculating the heat flux & temperature fields, and has been employed by many researchers to model the Hearth of Blast Furnaces. Proceeding from the initial geometry of the Hearth, as provided in the general arrangement drawing of the thermocouples, the structure is modeled as a mesh. A simplified 2D Axis symmetric structure is considered in place of the real 3D structure. Care is to be taken that the boundaries of refractory bricks of a common class are modeled with fidelity. In addition the locations of the thermocouples have to be faithfully recorded. The thermal & mechanical properties of the refractory materials are included in the FE model.
• the boundary conditions comprise of the Hot Metal temperature [1450 DegC] in the interior of the furnace, and the ambient temperature [40 DegC say] at the exterior of the shell.
• the temperature & heat fluxes at the mesh are readily computed based on standardized software. In ideal conditions the calculated and the measured temperatures should match. This is found to be so in the initial de novo state of the Blast Furnace. But as time progresses, the measured temperatures tend to increase.
• Gaps develop between the refractory and the steel shell.
• the discontinuity provides an impediment to the heat flow, and leads to a rise in the refractory temperature.
• the coke body comprising the "Dead Man Zone” influences the metal flow, and directs the fluid stream towards the refractory wall in an unpredictable manner.
• thermocouple temperatures change dynamically, and differ from the static predictions of the FE calculations.
• the problem is to estimate the thermal conductivity of the refractory bricks. As explained above, the properties of the refractories degrade during the course of their service life. Cracks in the refractory bricks would impede the heat flow. Conversely if the interstitial spaces become filled with hot metal which subsequently solidifies, the heat conductivity would increase. The hot metal is at 1450 DegC. At such high temperatures, there is considerable thermal expansion. The outer regions of the furnace being cooled to ambient temperatures, would mean that these regions are not subjected to thermal expansion. To compensate for these unequal expansions, a region of about 50mm is loosely packed with a mixture known as the "ramming mass". The steel shell would serve to withstand the thermal stresses induced in the inner layers in excess of the compensating ramming mass layers.
• the method would change the conductivity to 12 watts/M/DegC, then perform the FE analysis, re-compute the temperature of node 1001 to 160 DegC and continue till the convergence criterion is satisfied.
• the subject of this invention is to monitor the thermocouple temperature readings, and interpret the temperature field through a 2D axis symmetric Finite Element Analysis technique, to provide an estimate of the degradation of the refractory layers. Further this invention derives a superior technique to solve the inverse problem based on global search criterion.
• a basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
• Another object of the present invention is to provide a method to determine the position of the left out refractory lining in the hearth of a Blast Furnace.
• Another object of the present invention is to provide a system to determine the position of the left out refractory lining in the hearth of a Blast Furnace.
• Another object of the present invention is to provide means for accurate determination of the position of the left out refractory in the hearth of a blast furnace.
• thermocouples are placed in pair in-line. Any arbitrary configuration of thermocouples can be entertained, and equal credence is placed on all the sensors when deriving the refractory profile.
• a typical thermocouple layout is shown in [Fig#1].
• the refractory bricks are modeled as a 2D axis symmetric FE problem as shown in [Fig#2]
• thermocouple sensors typically about 350 thermocouple sensors are used in hearths of large modern Blast Furnaces.
• the results are to be interpreted and displayed as wear profiles typically updated once during the course of the day. Since the search technique that is the subject of this invention is time consuming, it is necessary that the individual iterative calculations be performed in 3 sec say, so that typically 24000 calculations can be performed to arrive at the wear profile over all sectors.
• the advantage of this invention is that in addition to the wear profile, it provides an integral validation tool, in that it predicts the temperature field over the entire hearth, which can be checked against the measurements. While it will be apparent to all conversant in the art, that the method can be performed in 3D analysis, the present description is confined to 2D.
• the structure of the Blast Furnace hearth is modeled in 6 sectors.
• the asymmetry introduced by the tapholes is ignored in this description, although it will be apparent that the tap-holes can be readily included in a 3D representation.
• the 6 sectors are individually analyzed as axis symmetric 2D FE thermal analysis problems.
• the mesh is constructed from the construction cross-section drawing, so that the nodes match the layout.
• thermocouples should measure monotonically increasing values. To achieve this, the temperatures are stored in a data base, and the campaign maxima values are used in the refractory wear calculations.
• a temporary protective layer forms over the remnant refractory lining, known as the skull. This is also estimated based on the 1 150 DegC solidus contour line. The difference is that whereas the refractory wear profile is estimated based on the campaign maxima, leading to a monotonically increasing wear profile, the skull is inferred from the current temperatures. If the current temperatures fall, it is reflected in an increased skull layer thickness over the refractory lining.
• the present invention provides a computer program implemented method of estimation of the left out refractory lining profile in the hearth of an operating blast furnace, wherein said method being based on sensing temperatures by means of plurality of sensor means located in the hearth of the blast furnace, said sensor means being desirably located at predetermined sectors of the hearth, said method comprising steps of :
• the present invention provides a computer program implemented method of estimation of the skull profile over left out refractory lining profile in the hearth of an operating blast furnace, wherein said method being based on sensing temperatures by means of plurality of sensor means located in the hearth of the blast furnace, said sensor means being desirably located at predetermined sectors of the hearth for sending the temperatures related data to recording and storing means which is an integral part of the said computing device or optionally an external memory device or a repository which when loaded/installed with the computing device for providing the stored data when needed during simulation, said method comprising steps of :
• the present invention provides a computer program implemented method of estimation of total protective thickness of single sector of the hearth of an operating blast furnace, said method being performed by using genetic algorithm.
• the present invention provides a computer program implemented method for indicating areas of dangerous wear in the remnant refractory lining, said method comprising indicating tuyeres to be closed and improved hearth cooling to be implemented.
• the present invention provides a computer implemented method for locating areas where cracks in the refractory have permitted slivers of hot metal to penetrate.
• the present invention provides a computer program implemented system for estimating the left out refractory lining profile in the hearth of an operating blast furnace, wherein said system comprising
• the present invention provides a computer program implemented system for estimating the skull profile over left out refractory lining profile in the hearth of an operating blast furnace, wherein said system comprising
• Fig #1 illustrates a typical thermocouple layout in a new blast furnace lining.
• Fig #2 illustrates aFE mesh geometry of the Blast Furnace Hearth
• Fig #3 illustrates Refractory & Skull of a Blast Furnace Hearth using Isometric morphing over all sectors.
• Fig #4 illustrates insertion of thermocouple near Elephant foot/Tap hole.
• Fig #5 illustrates a Cross section of Hearth at taphole location showing thermocouple locations.
• Fig #6 illustrates longitudinal section of hearth at location of taphole
• Fig #7 illustrates Re-meshing of refractory profile after knowing size of elephant's foot
• Fig #8 illustrates a flow chart for estimating temperature profile for every individual of the GA population using finite element method.
• Fig #9 illustrates a flow chart for estimating total protective thickness for single sector of single day using genetic algorithm.
• Fig #10 illustrates a flow chart for estimating skull thickness and left out refractory lining thickness.
• Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
• the initial conductivity values are recorded from the refractory brick manufacturer's specifications.
• the technique of genetic search algorithms is well known in the art. These generally refer to binary variables.
• a technique credited to [Ref#4] is used for continuous variables.
• the conductivities of the defined set of bricks [say 10] are selected from a search algorithm based on the genetics of natural selection. The range maximum and minimum are defined. A random number selection between these limits is taken in the first member of the first population.
• a similar method is used to construct the second member of the first population, repeated for the predefined population size [say 50].
• the temperature field is derived from a standard program [Ref#5].
• the RMS difference between the calculated & measured values is taken as the index of suitability for each member of the first population.
• the set of members [50] are assigned a weight according to suitability.
• Step#1 In the second [daughter/offspring] population, the parents are randomly selected based on a roulette wheel area aligned to the suitability weight.
• Step#2 The cross-over function is implemented by taking an arbitrary cut somewhere [say 3] along the set of bricks [10], whereby the first daughter has the conductivities of the first[ 3] bricks from the father and the remaining [7] bricks from the mother.
• the location of the cut is randomly determined. Since this is binary, while the extension is to continuous variables, at the location of the cut a continuous smoothening is implemented.
• the mutation function is affected based on a prescribed mutation rate [say 2%]. A random number is generated for each of the bricks [10], if it is found below this prescribed rate [ ⁇ 0.02] the assigned conductivity is replaced randomly with a value between the limits.
• a second daughter derives the first [7] conductivities from the father & the last [3] from the mother.
• the mutation function is repeated.
• the third/fourth daughters are derived from a second pair of parents identified randomly from the first population [50] based on the selection weights. This procedure repeats till the set of members of the second population [50 members] is completed.
• Step#2+3+4 Then the FE technique is repeated with the members of the second population. This has been shown in the first step.
• the procedure outlined above has to be executed twice, once with the campaign maxima temperatures to derive the refractory wear profile, and a second time with the current temperatures, to derive the skull profile over the worn refractory lining. Calculation times
• T bT T b, T dT dT
• k r and k z are thermal conductivities of the material in radial and axial direction respectively
• n r and n z are component of boundary in radial and axial direction respectively
• T b T is temperature boundary condition.
• Ni is shape function for / h node for any element.
• ⁇ T ⁇ are nodal temperatures, which can be obtained by solving above equation.
• the methodology and techniques described with respect to the aforesaid embodiments can be performed using a machine or other computing device within which a set of instructions, when executed, may cause the machine to perform any one or more of the methodologies discussed above.
• the machine operates as a standalone device.
• the machine may be connected (e.g., using a network) to other machines.
• the machine may operate in the capacity of a server or a client user machine in a server-client user network environment, or as a peer machine in a peer-to-peer (or distributed) network environment.
• the machine may comprise a server computer, a client user computer, a personal computer (PC), a tablet PC, a laptop computer, a desktop computer, a control system, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine.
• a set of instructions equential or otherwise
• the machine may include a processor (e.g., a central processing unit (CPU), a graphics processing unit (GPU, or both), a main memory and a static memory, which communicate with each other via a bus.
• the machine may further include a video display unit (e.g., a liquid crystal display (LCD), a flat panel, a solid state display, or a cathode ray tube (CRT)).
• a video display unit e.g., a liquid crystal display (LCD), a flat panel, a solid state display, or a cathode ray tube (CRT)
• the machine may include an input device (e.g., a keyboard) or touch-sensitive screen, a cursor control device (e.g., a mouse), a disk drive unit, a signal generation device (e.g., a speaker or remote control) and a network interface device.
• an input device e.g., a keyboard
• a cursor control device e.g., a mouse
• a disk drive unit e.g., a disk drive unit
• a signal generation device e.g., a speaker or remote control
• the disk drive unit may include a machine- readable medium on which is stored one or more sets of instructions (e.g., software) embodying any one or more of the methodologies or functions described herein, including those methods illustrated above.
• the instructions may also reside, completely or at least partially, within the main memory, the static memory, and/or within the processor during execution thereof by the machine.
• the main memory and the processor also may constitute machine-readable media.
• Dedicated hardware implementations including, but not limited to, application specific integrated circuits, programmable logic arrays and other hardware devices can likewise be constructed to implement the methods described herein.
• Applications that may include the apparatus and systems of various embodiments broadly include a variety of electronic and computer systems. Some embodiments implement functions in two or more specific interconnected hardware modules or devices with related control and data signals communicated between and through the modules, or as portions of an application-specific integrated circuit.
• the example system is applicable to software, firmware, and hardware implementations.
• the present disclosure contemplates a machine readable medium containing instructions, or that which receives and executes instructions from a propagated signal so that a device connected to a network environment can send or receive voice, video or data, and to communicate over the network using the instructions.
• the instructions may further be transmitted or received over a network via the network interface device.
• machine-readable medium can be a single medium
• machine- readable medium should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that store the one or more sets of instructions.
• the term “machine- readable medium” shall also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present disclosure.
• machine-readable medium shall accordingly be taken to include, but not be limited to: tangible media; solid-state memories such as a memory card or other package that houses one or more read-only (non-volatile) memories, random access memories, or other re-writable (volatile) memories; magneto- optical or optical medium such as a disk or tape; non-transitory mediums or other self-contained information archive or set of archives is considered a distribution medium equivalent to a tangible storage medium. Accordingly, the disclosure is considered to include any one or more of a machine-readable medium or a distribution medium, as listed herein and including art-recognized equivalents and successor media, in which the software implementations herein are stored.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Furnace Housings, Linings, Walls, And Ceilings (AREA)
• Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=49226237

Family Applications (1)

Country Status (1)

Cited By (5)

Family Cites Families (3)

• 2013
  • 2013-08-20 WO PCT/IB2013/056752 patent/WO2014030118A2/fr not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events