Structural modeling and meshing of blast furnace using TCL/Tk scripting.
Structural Modeling and Meshing of Blast Furnace Using HyperMesh And Tcl/Tk. Debiprasad Ghosh Bhaskar Sengupta Shyam Kr. Maitra Sujan Hazra Sr. Manager, Tech cell Head, Tech cell Consultant, Tech cell Sr. Engineer, Tech cell M&M, L&T Construction M&M, L&T Construction M&M, L&T Construction M&M, L&T Construction th th th th 6 Floor, Technopolis, 6 Floor, Technopolis, 6 Floor, Technopolis, 6 Floor, Technopolis, Saltlake-700091, India Saltlake-700091, India Saltlake-700091, India Saltlake-700091, India Abbreviations: FEA- Finite element analysis. Keywords: Blast furnace, TCL/Tk, CDB format, Ansys AbstractThe generation of geometry and meshing is done automatically using HyperMesh with the help of Tcl/Tk scripting language, with ameans to conduct iterative analysis of a blast furnace (an industrial structure) using finite element method. Material properties,boundary conditions, loading and other input parameters are also given automatically to the script for iterative solution requirements.Mesh-refinement is generally required at the critical locations for more accurate results. The proposed script in this study will be usefulto analyze any dimensions of blast furnace, material properties, loading and at different orders of discretization. These results are takenby a designer to design a safe and economical blast furnace for an industry.IntroductionMore than 85% of the world steel production is through the blast furnace route. Blast furnaces continue tobe the prime choice on account of versatility of operation, large production volume and lower cost ofproduction. However, Blast Furnaces are not only capital intensive, they also require significant time fordesign & erection of the various components comprising the Blast furnace shell, its refractory coolingarrangements, charging equipment, gas cleaning plant, cast house equipment, blast furnace hearthrefractory etc. This paper discusses an approach where the Blast Furnace is designed on the basis of a setof empirical rules applied to a handful of parameters. As a first attempt, some components of the BlastFurnace have been ignored - cooling arrangement, up-comers, charging equipment & blast equipment.Because of the huge financial impact, all efforts are made to design a reliable & economical Blast Furnace,one that will have a long campaign life and achieve a throughput in excess of 8500 t/day.In the present paper we are using Ansys for finite element analysis (FEA) and HyperMesh for FEA meshingof blast furnace [Figure 1]. The function of a blast furnace is to chemically reduce and physically convert ironoxides into liquid iron called "hot metal". The blast furnace is a huge, steel stack lined with refractory brick,where iron ore, coke and limestone are dumped into the top, and preheated air is blown into the bottom [1,2, 3]. The raw materials require 16 to 18 hours to descend to the bottom of the furnace where they becomethe final product - liquid slag and liquid iron. These liquid products are drained from the furnace at regularintervals. The hot air that is blown into the bottom of the furnace ascends to the top in 6 to 8 seconds afterreacting with the raw materials. Once a blast furnace is started it will continuously run for four to ten yearswith only short stops to perform planned maintenance.Simulation Driven Innovation 1
Process MethodologyGeometric modelling of blast furnace is created in HyperMesh with required material properties, boundaryconditions and loading. Finite element meshing is obtained from HyperMesh, which is then exported to atext file of Ansys CDB format. Finally, Ansys-mechanical solver performs the finite element solution andprovides result in “.rst” format, which is imported from HyperView for iterative modification. These repetitivemodelling, meshing and solution are performed using HyperMesh TCL/Tk programming integrating withHyperMesh GUI. Figure 1: Overview of program flow 3This program requires a handful of input parameters (Blast Furnace Effective Volume: 4000 M ), and on thebasis of a few empirical rules [Ref 1], the program generates the list of tentative Blast Furnace dimensions(Total Height, Belly Diameter, Hearth Diameter, Tuyere Height, Hearth Height, Blast Furnace top diameteretc…). Based on experience these dimensions can be edited from HyperMesh UI Tab, and then TCL/Tkprogram will generate a “.cdb” file, wherein the geometrical dimensions as well as the mechanical & thermalloads and the boundary conditions are created in an input file. The iterative steps are outlined in theschematic, where we check for the maximum seismic and pressure deflections & thermal stresses, andmake changes to the dimensions (Tuyere height 4600 mm), and the loading conditions (the location of theSimulation Driven Innovation 2
cooling staves and the cooling water flow rates), then generate a new input file for the next Ansyssimulation.Total modeling is performed in six stages - solid modeling; meshing; application of boundary condition;export to CDB format; solution; and Import from HyperView ; HyperView.Solid Modeling: Solid modeling of blast furnace is constructed using a set of solid cones extracted fromother set of solid cones. Different parts of a iron making blast furnace are Hearth, Boss, Belly, Stack, and an rth,Throat. The lower part of blast furnace, the hearth consists of a packed bed of coke particles through which hearth,liquid hot metal flows during tapping. In the present model only Firebricks are modeled a and internal hotmetal/cokes/ore are considered as load.Outer steel shell of the blast furnace is not solid modeled, which is face extracted from 3D brick elements to eelget nodal coincidence between brick and shell elements.For simplicity with mapped meshing, tapholes, tuyeres and staves are not considered in the model. uyeres Figure 2 Interactive modeling of blast furnace using Tcl/Tk 2:Meshing: Solid modeling of blast furnace provided 3D geometry of the blast furnace. To g response of getblast furnace under structural and thermal loading using finite element analysis, required meshing of this loading,solid model. Mapped meshing is used to get good quality hexagonal brick mesh. Once 3D elements arecreated, 2D shell elements for outer steel shell of blast furnace are face lifted from 3D elements. Suchtechnique will generate shell elements even for internal, top and bottom surfaces as well, which are deletedafterward. This deletion of extra shell elements i done using following steps etion isSimulation Driven Innovation 3
1. Get nearest node from a particular point 2. Get the elements connected on face 3. Delete the elements.Now material and real constant properties are provided for both brick and shell elements. are Figure 3: meshing of blast furnace using Tcl/TkApplication of Boundary Condition: Application of both thermal and structural boundary condition can beapplied either on solid modeling, or on the generated mesh. In the present paper boundary conditions are paper,applied in the mesh. Nodes at the bottom of blast furnace are considered as structurally fixed. The seismic eload is taken as 25% of the self weight in the horizontal direction, where the self weight includes the weightof the structure as well as the weight of the internal burden in the furnace. The second important loadingcondition is due to the internal pressure, typically 2 atmospheres in the modern furnaces. Similarly, different etemperature boundary conditions are applied at bottom, internal, and external wall of the furnace. Thesegive rise to thermal stresses because of the unequal expansion of the refractory lining and the steel shell. iveModern Blast Furnaces have extensive cooling arrangements, and the operational heat loads can fluctuate 2by an order of magnitude over their nominal values (40 mJ/m /Hr). These give rise to severe temperature .fluctuations with their attendant thermal stresses, and these also have been ignored in the model to arrive model,at a preliminary design.Export to CDB Format: Once Model is ready with nodes, elements, materials, boundary conditions, Ansysprofiles, and Ansys solution commands, these can be exported in Ansys CDB format.Simulation Driven Innovation 4
Solution: Solution is fired from TCL script using “exec AnsysRun.bat” command within a “try block”, where“AnsysRun.bat” file contains Ansys batch solver command for finite element solution. Ansys solver whichwrites results in Ansys “.rst”/”.rth” file.Import from HyperView: To view and take design decision, generated Ansys “.rst” or “.rth” file is openedfrom HyperView.Results & DiscussionsFigure 4 shows the stress contour of the blast furnace shell for structural and thermal loading. Figure 4: Stress contour from HyperViewBenefits SummaryManual repetitive modeling of blast furnace is time consuming as well as prone to manual error. Presenttechnique reduces the requirement of man power and gives opportunity to concentrate on the otherimportant design issues of blast furnace (design parameters, several alternative cooling staveconfigurations) easily, which should be examined before a satisfactory arrangement can be finalized.ChallengesFirst challenge we have faced in our project is regarding interoperability between HyperMesh/HyperViewand Ansys, where Altair India and USA technical team had helped to overcome the difficulty. Anotherchallenge is regarding the TCL/Tk language; as not being an object oriented family. Programmers with bigprojects are mostly available for object oriented (Java, C++, C#), or more recently multi-paradigm, functionallanguages (Python, F#). Even after development, big projects using other family of languages are difficult tomaintain, extend and test. Anyway, extensive uses of namespaces are applied to overcome this challenge.Although ScriptView is not yet mature, it also helped a lot.Simulation Driven Innovation 5
Future PlansSolidThinking can be used for solid modeling of blast furnace with tuyeres, and staves. Moreover, thesedesign technique can be extended using solver and optimization features of Altair software like OptiStruct,RADIOSS etc…ConclusionsA computational framework is created to model blast furnace in HyperMesh, Analyze in Ansys APDL andviewing results in HyperView using TCL/Tk programming. Automatic modeling technique had givenopportunity to concentrate on important design related issues. ACKNOWLEDGEMENTSThe authors would like to thank Subir Roy, Anand Ronad, Dev Anand, Shashi Kumar, Sujatha K G, JyotsnaNaveen, Rajas Majumdar, Nitin Chirdeep, Ramesha B S, Shashi Mantrawadi, Vishwanath Rao; AnshumanPanda, Kiran Chakravarthy of Altair Engineering for their kind help during the development of project andsubmission of paper in the HTC2012. REFERENCES Eu. F. Wegmann, "A Reference Book for Blast Furnace Operator," Translated from the Russian by V. Afanasyev, Mir publishers Moscow. M. Geerdes, H. Toxopeus, C. van der Vliet, “Modern Blast Furnace Ironmaking”, Verlog Stahleisen GmbH. Anil K. Biswas, “Principle of Blast Furnace Ironmaking”, Cootha publishing house.Simulation Driven Innovation 6