Department for Industrial Furnaces and Heat Engineering of ... · material has been created over the years, which are partly summarized in the books “Taschenbuch Industrielle Wärmetechnik”

1273-2017 heat processing

This is where we focus in regular intervals on the main institutions and organizations active in the field of thermoprocessing technology. This issue spotlights the Department for Industrial Furnaces and Heat Engineering of the RWTH Aachen.

Department for Industrial Furnaces and Heat Engineering of the RWTH Aachen

The main objectives of the Department for Industrial Furnaces and Heat Engi-

neering of the RWTH Aachen University in Germany [1] are the tasks of process and technical plant optimization for the fields of manufacturing, processing and recycling of iron and steel, non-iron-met-als, glass and ceramics. The department is part of the Faculty of Georesources and Materials Engineering (Faculty 5 of the RWTH Aachen University) in the Division of Materials Science and Engineering [2]. There have regularly been articles concern-ing the Department of Industrial Furnaces and Heat Engineering which was founded in 1957, e.g. [3–8].

Since 1998, the head of the institute has been Univ.-Prof. Dr.-Ing. Herbert Pfeifer and since this time the infrastructure of the institute has grown and undergone many changes.

In 2005, for the first time the institute has a technical center at its disposal, which makes it possible to carry out pilot plant

scale experiments for industrial furnace applications. This had previously not been possible due to a lack of available space in the former building in which the institute was located from 1971 to 2008.

Fig. 1 shows the interior of the techni-cal center, whereby the present focuses of the experimental set-ups in the hall are electrically heated furnaces for annealing experiments under vacuum up to a tem-perature of 1,600 °C or protective gas and water models for experimental investiga-tion of complex flows relevant for metal-lurgical applications (continuous casting, strip casting, AOD-converter) with different laser measurement systems.

The structural condition of the former building led to a short-notice moving-out of all the institutes within the building in 2008. For the institute lOB, this meant moving into a neighboring administration building and at the same time the start of the planning and construction of a new building close to the previous location of

the institute in the Kopernikusstrasse. The foundation stone ceremony took place in March 2009 and the roof was completed in November 2009. A year later, in November 2010, the institute could finally move into the new building shown in Fig. 2, which the lOB shares with the Institute for Materi-als Chemistry. Now the offices, the seminar room, the library as well as the technical and electrical workshop of the institute are located in the new building. The new complex also includes a 500 m2 large hall, in which it is now possible to realize and test further large experimental set-ups. Amongst other things, the infrastructure includes a natural gas-supply of 300 m3 (STP)/h and a 5 t crane.

At present, the institute has 18 scientific assistants, one scholarship holder, and one visiting scientist. Moreover, the institute has 8 administrative employees, of whom 5 are employed in the technical workshop. In addition, there are 2 apprentices and approximately 25 student research assis-

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Fig. 1: Interior view of the technical center Fig. 2: New building for the department from 2010

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tants working at the institute.This year the institute celebrated its 60th anniversary with a colloquium. For this rea-son the 1st Industrial Furnaces and Thermo-process Colloquium took place in Aachen in May 2017. There was the opportunity to present the state of the art in industrial furnace technology and discuss future task and opportunities for the industry.

COURSESThe institute offers lectures, tutorials and laboratories for the following degrees of the Faculty of Georesources and Materials Engineering

■ Werkstoffingenieurwesen (B.Sc. and M.Sc., held in German)

■ Wirtschaftsingenieurwesen, Fachrich-tung Werkstoff- und Prozesstechnik (B.Sc. und M.Sc., held in German)

Lectures are also offered for other faculties, for instance for the degrees

■ Umweltingenieurwesen (Environmental Engineering)

■ Automatisierungstechnik (Automation Technology)

The lecture “Transport Phenomena” con-cerns the basics of heat transfer and fluid mechanics. The course “Simulationstech-nik” (numerical simulation technology) is offered not only as a bachelor course but also as a CFD-course for master students.

One of the main aims of the institute is to motivate students to have an interest in and study the course “Industrieofentech-nik” (industrial furnace technology). In order to do so, a considerable amount of lecture material has been created over the years, which are partly summarized in the books “Taschenbuch Industrielle Wärmetechnik” [9], “Pocket Manual of Heat Processing” [10] and “Praxishandbuch Thermoprozesstech-nik I, 11” [11–12]. This course contains exten-sive laboratories, which take place in the technical centre of the institute as well as excursions to commercial firms and indus-trial plants.

In addition to the university courses, since 2002 the seminar “Industrieofen-technik - Grundlagen und Anwendung” (industrial furnace technology - basics and application) is regularly offered in coop-eration with the Steel Academy IFB. Since

2007 the seminar “Rationeller Energieein-satz” (efficient energy use) is also offered in cooperation with the Steel Academie IFB. Furthermore, the institute regularly contrib-utes articles to the seminar “Elektrotechnik des Lichtbogenofens” (electrical engineer-ing of electric arc furnaces) as well as the seminars of the FOGI (Forschungsgemein-schaft Industrieofenbau).

INDUSTRIAL FURNACES TECHNOLOGYThe working group “industrial furnaces technology” is active in the field of fluid flow and heat transfer research concern-ing preheating- and annealing-furnaces. The main emphasis of the investigations is on furnaces of the aluminium and copper industry, where the heating is dominated by convection, but also various furnaces in the steel industry. Key activities are process development and optimization.To improve the energy and ressource effi-ciency of heat treatment plants like indus-trial furnaces, a profound understanding of the fluid mechanics and thermodynamic is essential. Processes are investigated by physical and numerical models. Therefore, different experimental set-ups with a wide range of measurement equipment exists. Besides volume flow and temperature measurement, Laser Doppler Anemom-etry (LDA), Particle-Image-Velocimetrie (PIV) or Laser-Induced Fluorescence (LIF) are used. In addition empirical and numeri-cal models as well as simulation models, based on Computational Fluid Dynamics (CFD) are available tools. The combination of experimental and numerical approaches enable detailed investigation of the physi-cal processes.Besides the research activities presented in the past, the actual research topics are the areas of:

■ Industrial furnaces aerodynamics and fluid mechanics

■ Modelling and simulation ■ Combustion and burners

INDUSTRIAL FURNACES AER-ODYNAMICS AND FLUID MECHANICSTo design an industrial furnace a broad

Fig. 3: Test rig for the determination of heat transfer distribution


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understanding of the furnace aerodynamic and fluid mechanics is essential. In indus-trial furnaces, dominated by convection, the volumetric flow rate is an important process variable. The institut developed a measurement system to quantify the vol-umentric flow rate of a process with low tolerance. Within this project, funded by the AiF, additional fundamental research with laser optical systems was done, to gain a better understanding of the flow phenomena [13].In the processes often fans are used to deliver the required volumetric flowrates. Actual research focus on the development of cross-flow fans for thermoprocess plants, which can be used for operating tempera-tures up to 500 °C. Compared with other typs of fans used in industrial applications (e. g. centrifugal fans, axial-flow fans), cross-flow fans provide a constant flow across the channel width. This has positve effects on the temperature distribution of the load and therefore its product properties. A problem for the design and construction of the fan are the determination of thermal stresses and operating parameters, which should be quantified as part of the project.

Another research topic focus on the sta-bility of metallic strips under the influence of nozzle fields in cooling units. Aims of the project are the investigation of strip oscillation during gas cooling, the determination of sensitive parame-ters and the devel-opment of meas-ures for process optimization. The experimental and numerical investi-gations of differ-ent nozzle con-figurations show a strong influence on the oscillation of the strip over the whole width. In combination with the heat transfer coefficient the results of the

investigated cooling systems show a strong influence of the strip length in-between the clamps and the ratio of nitrogen and hydrogen in the cooling fluid. These are the main levers to improve strip stability.The determination of the heat transfer is essential for the characterisation of thermo-processes. For the quantification of the heat transfer for different nozzle systems an experimental set-up was designed and built up at the institute, which is also used in several industrial projects. Fig. 3 shows the test rig for the quantification of the heat transfer dristribution of a nozzle system.

MODELLING AND SIMULATIONDue to the need for ever more efficiency, the design of highly loaded components forces the designer closer to the limits of what is technically possibly. Therefore, it is of utmost importance to predict the occur-ring stresses and strains to which a compo-nent is subjected. Normally several phe-nomena, such as fluid flow, combustion, heat radiation and conduction, take place at the same time in thermoprocess plants, whose interactions have a large influence on the transient component loading. As the interdependence of the individual phe-nomena is often great, coupled simulations of these effects are becoming more and more relevant. In the thermoprocess tech-

nology field this fact leads to the necessity to couple the fluid flow and heat transfer phenomena in industrial furnaces (CFD) with the temperature- and stress- distri-bution of furnace components being con-sidered (CSD - Computational-Structure-Dynamics) [14].

If the results show, that the interaction between the fluid flow and structure of a component leads to a change in the shape of the component that in turn has no rel-evant effect on the flow field, then the analysis is referred to as a one-way coupled analysis. In this case the CFO and CSO can be carried out separately.If, however, interactions between fluid flow and deformations occur, for example if deformations due to the flow in turn cause changes in the flow field, then the influence of the changed flow field on the deformed component must be considered. This so-called two-way coupling requires an iterative solution of both, CFO and CSO, and must generally be carried out when large deformations of components occur.

One application example for this approach is the calculation of thermal induced stress in radiant tubes [15–17]. The stress distribution in Fig. 4 for example, shows highly loaded regions, firstly there where the tube is fixed in position close to the wall, at the elbow farthest away from

Fig. 4: Distribution of temperature (upper figure) and thermal induced stresses (lower figure) at the sur-face of a p-type radiant tube


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the wall and at the connection between the elbow and the straight section, close to the wall. These regions are especially critical for the investigated radiant tube, as these are the regions where welding seams are located, which usually means lower allowable maximum stress values. In these regions the stresses are much higher than the temperature dependent allow-able yield stress, so that plastic deformation takes place. High temperature gradients, as for example those close to the wall, are also the cause of higher stress regions. The use of coupled FSI-simulations therefore clearly

delivers definite information concerning the optimization of thermally highly loaded furnace components.

COMBUSTION AND BURNERSA large number of industrial furnaces is gas fired. The optimization of the process and furnace parameters needs detailed information of flow and combustion phe-nomena, which often requires fundamental research. An example is the use of laser-induced fluorescence of OH-radicals to visualise the reaction zone of the combus-tion or the particle-image-velocimetrie to

determine the flow pattern [18-20]. These investigations provide fundamental infor-mation of the energy transformation in industrial plants.

Another research focus of the group combustion and burners are the inves-tigation and optimization of energy effi-cient, low emission combustion concepts. An example is the flameless combustion. As part of a research project, funded by the BMWi, the technical limits of this tech-nique for low and high burner capacity were investigated [21–22].To increase energy and resource efficiency a concept for a scale free reheating of semi-finished metal products was developed. The process consists of fuel rich combus-tion in the furnace, post-combustion and heat exchange for combustion air pre-heating [23–24]. The experiments show an almost complete reduction of scale formation on the surface of copper and copper nickel alloys at an air ratio of 0.96. For the reheating of steel there is a scale reduction of approximatly 50 % by chang-ing the furnace atmosphere from fuel lean condition with an air ratio of 1.15 to fuel rich conditions with an air ratio of 0.95. The furnace atmosphere can be generated by conventional recuperative burners, but there is a post-combustion before the heat exhanger necessary.

Based on the results of this project a energy efficient burner for heat treatment furnaces with a low oxidizing atmosphere is developed [25–26]. This project is funded by the central innovation programme for small and medium-sized enterprises (ZIM). The main aim of the research project is the development of a new burner. This burner consists of a conventional recuperative burner with integrated post-combustion in an annular gap between the burner and an open radiant tube. Experimental and numerical investigations to optimize the design of a prototype show good accordance. Fig. 5 shows the concept of the process and the CO concentration in the annular gap of the burner which was determined with experimental and numeri-cal methods.

Besides the mentioned projects, very practical orientated cooperation projects

Fig. 5: Burner for fuel rich combustion and post-combustion in an annular gap (upper figure); CO concentration in the annular gap (lower figure)


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are realised. These are for example the development of an interactive planning system for plasma-nitriding plants, the development of a hot isostatic press for the combined compressing and heat treatment of semi-finished products or the develop-ment of a multilayered chamber furnace for the press hardening of tailored blanks for automotive engineering to improve cost effectiveness.Another still emerging research topic are hybrid heating concepts (hybrid heating). Most of the industrial furnaces are using fos-sile fuels, especially natural gas, oil or coal. Against the background of the so called “Energiewende” (energy transition) conven-tional fuels shall be substituted more and more by electrical power from renewable sources and therefore contribute to the sta-bility of the electrical grid (power to heat). To implement these changes, systematic research and development of new innova-tive concepts for thermotechnical plants and industrial furnaces is needed.

ENERGY AND MASS BALANCESApart from the preparation of energy and mass balances, especially for the electric steelmaking process but also for other energy intensive high temperature pro-cesses, the research group is also active in process optimization and process develop-ment. For the preparation of balances and also for the development of process control strategies the group relies on long-time experience with the installation and opera-tion of off gas analysis systems at industrial high temperatures aggregates like the elec-tric arc furnace (EAF), Fig. 6. In addition the research group operates at the Herzogen-rath site an electric arc furnace in pilot plant scale. Furthermore, empirical and analytical modelling as well as simulations based on Computational Fluid Dynamics (CFD) are used. Examples for this work are the mod-elling and simulation of the gas flow and the electric arcs in the EAF using CFD [27], the modelling of the dedusting system of an EAF using Matlab [28–29] und its com-bination with a comprehensive dynamic process model of the electric steelmaking process [30–32]. Goal of the work in this area is usually the improvement of energy

and resource efficiency.In addition to the pro-

cess technology aspects of environmental meas-urements and the energy efficiency of processes are getting more important. The implementation of off gas measurements at dedusting plants serves the determination of mass flows relevant for the environment (e.g. dust, NOx, CO2 etc.) or for the efficiency (e. g. CO, O2). Apart from deter-mining the current state, fundamentals of pollutant formation are investigated and process control strat-egies to reduce or avoid environmentally relevant emissions and to improve the energy efficiency are developed and investigat-ed in pilot scale as well as industrially.

In times in which sus-tainability is a very impor-tant topic, the improve-ment of the resource efficiency of processes is a constant research topic. This includes not only the saving of raw materials or their substitution by alternative materials but also the reuse of by-products or wastes. Therefore the research into the substitution of fossil carbon sources by bio-mass in the electric steelmaking process is an important research area. Investigations have been conducted at laboratory and pilot-scale as well as in cooperation with industry at industrial plants. Within the successful project “Sustainable EAF steel production – GreenEAF” [33] funded by the EU the feasibility of the substitution of fossil coal by biomass and biochar could be proven. In the follow-up project “Bio-char for a sustainable EAF steel production – GreenEAF2” a market analysis as well as extensive industrial trials campaigns have been conducted [34–35].

Not only biomass but also slags and

other by-products or wastes are possible input materials for the EAF. In a ZIM project funded by the German BMWi the recycling of disintegrated ladle slag as a substitute for lime has been investigated [36].

Concerning heat treatments, the research group has several heat treat-ment furnaces at its disposal, in which trials regarding heat treatments as well as the sintering of materials within a wide temperature range and in different fur-nace atmospheres can be carried out. The vacuum heat treatment furnace of the IOB shown in Fig. 7 for example allows the car-rying out of experiments under vacuum or H2 or N2 atmosphere at temperatures of up to 1,600 °C and the subsequent quenching in N2 at furnace pressures of up to 10 bar.

With these heat treatment furnaces, the IOB conducts classical heat treatments, for

Fig. 6: Industrial electric arc furnace in operation

Fig. 7: Vacuum heat treatment furnace


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example stress relief annealing of compo-nents after forming or the hardening of tools as a service, for example as a service for other institutes of the RWTH Aachen. Concerning heat treatments with specific furnace atmospheres, investigations were carried out to determine the aging of cata-lyst materials at defined moisture contents of the atmosphere as well as regeneration experiments of diesel engine particle filters. In addition heat treatments in hydrogen, forming gas or C-level controlled atmos-phere have been carried out.

HIGH TEMPERATURE FLOWS IN METALLURGICAL MELTSThe working group “High Temperature Flows in Metallurgical Melts” focuses on the modeling of transport processes in metallurgical reactors. An increasing under-standing of the processes in metallurgical reactors (converters, ladles, tundishes and chill molds) is crucial to meet the require-ments of industry on metallic materials with the highest degree of purity and homog-enous, optimal technological properties

for life-time-increasing components. This is decisive for the optimization of the qual-ity of semi-finished products as well as of final components. The possibilities of flow measurements in metallurgical melts are very limited due to high temperatures, so the flow and thermal processes are investigated using physical and numerical models.The kinematic viscosities of metal melts and water are in the same area of magni-tude and for this reason their flow char-acteristics are almost equal. Therefore, an investigation of melts using water models is possible. The IOB has different water model test stands available in different sizes (for example tundish, mold, ladle, converter, strip caster). A variety of different measure-ment techniques are available to investi-gate the transport processes in the water models:

■ Visualization of fluid flow with laser light sheet technique

■ 3D measurement of turbulent fluid flow fields with DPIV and LDA

■ Measurement of temperature and con-

centration fields with LIF ■ Retention time measurement and anal-

ysis of mixing processes ■ Determination of particle distribution

and precipitation curves using Coulter Counter

■ Measurement of water level move-ments with ultrasonic sensors

Parallel to flow studies in physical models, numerical simulations are performed using CFD. In order to increase the accuracy of the calculations, the simulations are first carried out for the water flow and the free parameters are validated using the highly precise laser-optical measurement results. Subsequently, the simulations for the mul-tiphase, non-isothermal metal melts are carried out.The following sections provide an overview of three current research areas in the work-ing group.

INVESTIGATION OF MUL-TIPHASE FLOWS IN METAL-LURGYMultiphase flows play a major role in metal-lurgy, for example during process gas treat-ment as well as for the investigation of non-metallic particles in melts. The treatment of melts with process gases is common practice in metallurgy. Typical refining pro-cesses using process gas treatment are melt treatment in a steel ladle, copper refining in the copper converter, the AOD converter process and aluminum melt treatment. The numerical simulation of multiphase flows in metallurgy is particularly problematic in gas-liquid multiphase systems. The mul-tiphase model must be able to correctly reproduce both the interaction between the phases involved and the phase bound-ary between gas and liquid of immiscible fluids.The AOD process is used for the decar-burization of highly alloyed steels. In this process, the gases are introduced hori-zontally into the melt through sub-bath nozzles. Depending on the design of the AOD converter, low-frequency oscillations occur during operation. Within the scope of a research project in cooperation with the SMS Group, investigations of the fluid

Fig. 8: Presentation of transient flow field in a 120 t AOD converter (CFD simulati-on, four different instants, Frm = 662, hF / D = 0.56)


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mechanical phenomena in the AOD con-verter, which stimulate the vibrations of the surrounding structure, have been carried out at IOB [37–41]. The goal was to develop a mathematical model for the simulation of the flow in the converter and its interaction with the surrounding structure in order to predict occurring vessel vibrations. Fig. 8 shows the simulated flow field. The inter-faces between steel and slag (yellow) or slag and gas (red) are shown as colored ISO surfaces. The bubble beams are shown as ISO-surfaces of constant bubble-concen-tration. The coloring is carried out accord-ing to the local speed (absolute value of speed). Furthermore, the velocity vectors are shown in the symmetry plane of the converter.Another research project deals with the multiphase flow in a steel ladle. The ladle gas treatment is used to homogenize the melt with respect to its composition and temperature and to adjust it to defined val-ues. Furthermore, non-metallic particles are to be removed. The relevant research project aims to understand the basic mechanisms of the formation of the het-erogeneous bubble beam and the result-ing flow inside the ladle and to apply this knowledge to the further development of numerical models which describe the reac-tor with respect to the multiphase flow in a realistic manner. For this purpose, vari-ous influencing variables on the flow in the ladle are investigated in detail experimen-tally with the water model. Based on this, the numerical models are further devel-oped.

The numerical simulation of the mul-tiphase flow in the water model is realized with the combination of an Euler-Euler approach (VOF model) for mapping the motion of the water surface and an Euler-Lagrange approach (DPM model) to deter-mine the movement of the gas bubbles [42].

ESU AND VAR MAGNETOHY-DRODYNAMIC AND THERMAL PHENOMENAElectroslag remelting (ESU) is a special process in metallurgy with a consumable electrode. With this it is possible to achieve

a strictly defined chemical composition by utilizing various refining mechanisms while at the same time a controlled formation of the metal’s microstructure is achieved by controlled solidification.The basic structure of an ESU system is shown in Fig. 9. The required heat is gener-ated by the current flow between the elec-trode and the mold. The slag bath serves as a resistance element in which a large part of the electrical energy is converted into heat. Within various projects the ESU process was fundamentally investigated at the IOB [43–47].

In a current project a smaller drop size and a reduction of the metal film thickness at the electrode are to be achieved by the use of a rotating electrode in the ESU pro-cess and the resulting centrifugal force. A corresponding improvement of the refining is expected. The remelting of a rotating electrode represents a process innovation, which has been investigated only to a very limited extent up to now.

With a combination of experimental investigations at an experimental facility at the Institute of Process Metallurgy and Metal Recycling and numerical simula-tions the refining mechanisms as well as the inclusion distribution in the metal block shall be inves-tigated and understood for the exemplary nickel base alloy ‘Alloy 718’. The aim is to produce a material with an increased degree of purity and an improved solidification structure in a reproducibly manner. The investigation of the flow by means of com-puter-assisted simulations is divided into

an investigation of the macroscopic flow and a modeling of the refining mechanisms during the process. A three-dimensional, transient model for the multiphase flow and the magnetohydrodynamics is used to represent the occurring flow phenomena.

Vacuum arc remelting (VAR) is a refining process for the production of high-purity metallic materials. An already very pure electrode made of the relevant material is used, which has often been melted in a vacuum induction furnace and has been refined in the electroslag remelting pro-cess. The VAR system essentially consists of a water-cooled copper mold and a power supply to which the electrode is attached. An electric current is applied so that electrical discharges (arcs) occur between the electrode and the block. The energy released during this process is used to melt the bottom of the electrodes. After the mass is transferred in the form of metal drops, a metal pool is formed in the mold, which continuously solidifies towards the edge (Fig. 10).

In cooperation with VDM Metals GmbH, the VAR process is examined numerically at the IOB. The simulation of flow, heat con-tent and solidification is able to reproduce the shape of a metal pool known from

Fig. 9: Principle of electroslag remelting


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experiments, which is a decisive quality cri-terion. Thus, the resulting pool profile can be calculated with the model, even with slightly modified process parameters. [49–52]. The validation of the model is based on metallurgical micrographs of samples from the real process, which are compared to the simulation results (Fig. 11).

While it is quite common for electroslag remelting processes, which are related to the VAR process, to use a variety of differ-ent geometries, it is still common in the VAR process to perform the process only in cylindrical geometries. Potential savings in energy and subsequent process costs can,

for example, be provided by near-net-shape remelt-ing. The IOB is interested in the genera-tion of inno-vative further development possibilities of the VAR pro-cess by trans-ferring similar advantages of the different variants of the ESU process to the VAR pro-cess. Based on an exist-ing 2D VAR model for the study of axi-ally symmetric geometr ies , a 3D model was devel-oped, which allows the VAR process to be displayed in re c tangular geometries.

The exist-ing model is based on a 3-model-cou-

pling of electromagnetic FEM, thermo-elastic FEM and CFD to map the numer-ous phenomena in the VAR process (Fig. 12) which can provide conclusions on the solidification and flow behavior in the metal pool [53]. This is of great importance for the demanded material properties and enables first conclusions to be drawn about the effects of a changed process geometry.

AMAP „ADVANCED METALS AND PROCESSES“The research cluster AMAP (Advanced Met-als and Processes) was founded in 2012

with the idea of open innovation between industry partners and the RWTH institutes (Fig. 13).The goal is research, development and training in the field of materials technology for non-ferrous metals and their production and processing. The cooperation between industrial partners and RWTH institutes is based on 12 projects, which are widely spread in the field of materials science.Project P5 “Sustainable Recycling Con-cept: Efficient Melting”, in which the IOB is involved, focuses on the modeling of the heating and melting process of aluminum scrap, for example UBCs (“used beverage cans. Compared to the production of pri-mary aluminum, the recycling of end-of-life aluminum, such as beverage cans, is more energy-efficient and at the same time leads to significantly lower CO2 production.The contributions from the IOB are CFD modeling of the combustion process, in par-ticular flameless combustion, the (radi-ative) heat transfer to the material to be melted, and the pyrolysis of the adhering organics (lacquers and cooling lubricants) [54–59].Characteristic for the flameless combustion is the strong recirculation of the combus-tion products, which results in a reduced combustion temperature and a spatially extended reaction zone. The lack of the temperature peaks and thus a flame front causes a reaction zone which cannot be detected by the human eye. A numerical calculation of this procedure requires the integration of detailed and extended com-bustion reaction mechanisms.

Another part of the AMAP P5 is the investigation of pyrolysis gas release from various scraps, contaminated with organics, during heating. Experimental investigations are used to characterize the pyrolysis gas emissions in order to investigate the inter-actions of such gases with the melt and to integrate the emission in CFD simula-tions. For this purpose, small amounts of the relevant material are heated in a lab-scale muffle furnace with a defined heat-ing rate. Released gases are analyzed using analytical systems (FTIR etc.). The findings of this study allow conclusions to be drawn about the decomposition processes and

Fig. 10: Principle of the VAR process

Fig. 11: Comparison of the pool profile


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reaction mechanisms as well as the caloric contribution of the gases to the furnace energy balance.

LITERATURE

[1] http://www.iob.rwth-aachen.de/

[2] http://www.muw.rwth-aachen.de/

[3] Pfeifer, H.: Institut für Industrieofenbau und

Wärmetechnik der RWTH Aachen. gwi – gas-

wärme international 55 (2006) 7, p. 509-512

[4] Pfeifer, H.; Köhne, H.: Forschungs- und

Entwicklungsaktivitäten am Institut für

Industrieofenbau und Wärmetechnik der

RWTH Aachen. ewi – elektrowärme interna-

tional 62 (2004) No. 3, p. 126-133

[5] Institut für Industrieofenbau und Wärme-

technik der RWTH Aachen. gwi – gaswärme

international 55 (2006) No. 7, p. 509-512

[6] Pfeifer, H.; Bölling, R.; Echterhof, T.; Rückert,

A.: Institut für Industrieofenbau und

Wärmetechnik der RWTH Aachen. gwi –

gaswärme international 60 (2011), No. 4, p.

319-326

[7] Pfeifer, H.; Bölling, R.; Echterhof, T.; Rückert,

A.: Institut für Industrieofenbau und

Wärmetechnik der RWTH Aachen. ewi – ele-

ktrowärme international 69 (2011), No. 3, p.

178-185

[8] Echterhof, T.; Pfeifer, H.; Rückert, A.; Gruber, J.:

Department of Industrial Furnaces and Heat

Engineering of RWTH Aachen University. heat

processing 10 (2012), No. 1, p. 105-113

[9] Pfeifer, H. (Hrsg.): Taschenbuch Industrielle

Wärmetechnik – Grundlagen, Berechnun-

gen, Verfahren. 4. Auflage. Essen: Vulkan-

Verlag, 2007

[10] Pfeifer, H.: Pocket Manual of Heat Process-

ing (Fundamentals, Calculations, Pro-

cesses). Essen: Vulkan-Verlag, 2008

[11] Pfeifer, H.; Nacke, B.; Beneke, F.: Praxishand-

buch Thermoprozesstechnik; Band 1

(Grundlagen – Prozesse – Verfahren). 2.

Auflage. Essen: Vulkan-Verlag, 2010

[12] Pfeifer, H.; Nacke, B.; Beneke, F.: Praxishand-

buch Thermoprozesstechnik; Band 2 (Anla-

gen – Komponenten – Sicherheit). 2.

Auflage. Essen: Vulkan-Verlag, 2011

[13] Perkowski, D.; Pfeifer, H.: Volumen-

strommessung bei Hochkonvektionsanla-

gen zur Wärmebehandlung. gwi – gas-

wärme international 62 (2013) 4, p. 61-65

[14] Lenz, W.; Pfeifer, H.: Berechnung von Ther-

mospannungen in Wärmebehandlungsan-

lagen mittels gekoppelter numerischer Ver-

fahren. Chemie Ingenieur Technik 85 (2013),

No. 8, p. 1312-1316

[15] Hellenkamp, M.; Bölling, R.; Giesselmann,

N.: Thermisch induzierte Spannungen am

Strahlheizrohr unter Berücksichtigung

von Fluid-Struktur-Interaktion. gwi – gas-

wärme international 60 (2011), No. 7-8, p.

609-614

Fig. 12: Coupling scheme of CFD and FEM [53]

Fig. 13: AMAP cooperation partners


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[16] Schmitz, N.; Hellenkamp, M.; Pfeifer, H.;

Cresci, E.; Wünning, J.; Schönfelder, M.:

Radiant tube life improvement for vertical

galvanizing lines. Proceedings of the AIST

Galvatech 2015 AIST, p. 473-480, 31. May - 4.

June 2015, Toronto, Canada

[17] Hellenkamp, M.; Pfeifer, H.: Thermally

induced stresses on radiant heating tubes

including the effect of fluid-structure inter-

action. Applied Thermal Engineering 94

(2016), p. 364-374

[18] Schnitzler, M.; Pfeifer, H.; Schwotzer, C.:

Untersuchung des Zusammenhangs zwis-

chen der Verteilung von Hydroxyl-Radi-

kalen und dem Wärmestrom beim Direct

Flame Impigement. 26. Deutscher Flam-

mentag, VDI-Berichte No. 2161, 11.-12. Sep-

tember 2013, Duisburg, p. 179-188

[19] Schnitzler, M.; Pfeifer, H.; Schwotzer, C.:

Examining heat transfer process of direct

flame impingement combining laser

induced fluorescense measurement of

hydroxyl radicals and conventional heat

flux measurements. Proceedings of the

European Combustion Meeting, 25.-28.

June 2013, Lund, Schweden

[20] Schnitzler, M.; Pfeifer, H.; Blankenstein, M.: PIV

measurements of the velocity distribution in

an impinging turbulent swirl flame. Proceed-

ings of the European Combustion Meeting,

30. March - 2. April 2015, Budapest, Hungary

[21] Blinn, S.; Schnitzler, M.; Pfeifer, H.; Wünning,

J. G.; Cresci, E.: Extension of the limitations

of use of flameless oxidation for small

burner capacities. Proceedings of the Euro-

pean Combustion Meeting, 30. March - 2.

April 2015, Budapest, Ungarn

[22] Blinn, S.; Schnitzler. M.; Pfeifer, H.; Cresci, E.;

Wünning, J.G.: Extension of the limitations

of use of flameless oxidation for small

burner capacities. Proceedings of the 10th

European Conference on Industrial Fur-

naces and Boilers, 7.-10. April 2015, Porto,

Portugal

[23] Schwotzer, C.; Schnitzler, M.; Pfeifer, H.: Zun-

derarme Wiedererwärmung von Metall-Hal-

bzeugen mit Rekuperatorbrennern. gwi – gas-

wärme international 65 (2016), No. 3, p. 67-72

[24] Schwotzer, C.; Schnitzler, M.; Pfeifer, H.; Ack-

ermann, H.; Diarra, D.: Low scale reheating

of semi-finished metal products in furnaces

with a central recuperator. heat processing

14 (2016), No. 3, p. 83-89

[25] Schmitz, N.; Schwotzer, C.; Pfeifer, H.; Sch-

neider, J.; Cresci, E.; Wünning, J.: Develop-

ment of an energy-efficient burner for heat

treatment furnaces with a reducing gas

atmosphere. 72. HärtereiKongress, 26.-28.

October 2016, Cologne, Germany

[26] Schmitz, N.; Schwotzer, C.; Pfeifer, H.; Sch-

neider, J.; Cresci, E.; Wünning, J.: Numerical

investigations on post-combustion in a

burner for heat treatment furnaces with a

reducing gas atmosphere. Proceedings of

the 11th European Conference on Industrial

Furnaces and Boilers, 18.-21. April 2017,

Albufeira, Portugal

[27] Gruber, J. C.; Echterhof, T.; Pfeifer, H.: Investi-

gation on the influence of the arc region on

heat and mass transport in an EAF freeboard

using numerical modeling. steel research

international 87 (2016), No. 1, p. 15-28

[28] Meier, T.; Hassannia Kolagar, A.; Echterhof,

T.; Pfeifer, H.: Process modeling and simula-

tion of an electric arc furnace for compre-

hensive calculation of energy and mass

transfers in combination with a model of

the dedusting system. 11th European Elec-

tric Steelmaking Conference & Expo, 25.-27.

May 2016, Venedig, Italy

[29] Kolagar, A. H.; Meier, T.; Echterhof, T.; Pfeifer,

H.: Modeling of the off-gas cooling system

for an electric arc furnace and evaluation of

the heat recovery potential. Chemie Inge-

nieur Technik 88 (2016), No. 10, p. 1463-1473

[30] Meier, T.; Hassannia Kolagar, A.; Echterhof,

T.; Pfeifer, H.; Logar, V.; Skrjanc, I.: Modelling

and simulation of the transient electric arc

furnace process. 1st European Steel Tech-

nology & Application Days (ESTAD) & 31st

Journées Sidérurgiques Internationales

(JSI), 7.-8. April 2014, Paris, France

[31] Meier, T.; Logar, V.; Echterhof, T.; Skrjanc, I.;

Pfeifer, H.: Modelling and simulation of the

melting process in electric arc furnaces –

influence of numerical solution methods.

steel research international 87 (2016), No. 5,

p. 581-588

[32] Meier, T.; Hay, T.; Echterhof, T.; Pfeifer, H.;

Rekersdrees, T.; Schlinge, L.; Elsabagh, S.;

Schliephake, H.: Process modeling and sim-

ulation of biochar usage in an electric arc

furnace as a substitute for fossil coal. steel

research international (2017)

[33] Bianco, L.; Baracchini, G.; Cirilli, F.; Moriconi,

A.; Moriconi, E.; Marcos, M.; Demus, T.; Ech-

terhof, T.; Pfeifer, H.; Beiler, C.; Griessacher,

T.: Sustainable EAF steel production

(GREENEAF), EUR 26208, Publications Office

of the European Union, (2013), Luxembourg

[34] Echterhof, T.; Demus, T.; Schlinge, L.;

Schliephake, H.; Pfeifer, H.: Use of palm ker-

nel shells as a substitute for charge coal in a

140 t DC electric arc furnace, SCANMET V –

5th International Conference on Process

Development in Iron and Steelmaking, 12.-

15. June 2016, Lulea, Sweden

[35] Demus, T.; Reichel, T.; Schulten, M.; Echter-

hof, T.; Pfeifer, H.: Increasing the sustainabil-

ity of steel production in the electric arc

furnace by substituting fossil coal with bio-

char agglomerates. Ironmaking & Steel-

making 43 (2016), No. 8, p. 564-570

[36] Abel, R.; Demus, T.; Echterhof, T.; Reichel, T.;

Dettmer, B.; Schliephake, H.; Algermissen,

D.; Drissen, P.; Mudersbach, D.: Entwicklung

eines Agglomeratsteins aus Gießpfannen-

schlacke und Biokohle zum Einsatz in Elek-

trolichtbogenöfen zur Einsparung von CO2

und Primärkalk. Report des FEhS-Instituts, 2

(2015), No. 2, p. 10-16

[37] Wuppermann, C.; Giesselmann, N.; Rückert,

A.; Pfeifer, H.; Odenthal, H.-J.; Hovestädt, E.: A

novel approach to determine the mixing time

in a water model of an AOD converter. ISIJ

International, 52 (2012), No. 10, p. 1817-1823

[38] Wuppermann, C.; Rückert, A.; Pfeifer, H.;

Odenthal, H.-J.: Bestimmung des Strömungs-


Edition 15 PROFILE+

feldes in einem Wassermodell eines AOD-

Konverters mittels PIV. Fachtagung „Laser-

methoden in der Strömungsmesstechnik“.

Deutsche Gesellschaft für Laser-Anemo-

metrie GALA e.V., 2010, Cottbus


Odenthal, H.-J.: Physical and mathematical

modeling of the vessel oscillation in the

AOD process. ISIJ International 53 (2013) No.

3, p. 441-449


Odenthal, H.-J.; Hovestädt, E.: Mathematical

modeling of fluid dynamics and vessel

vibration in the AOD process, CFD Mode-

ling and Simulation in Materials Processing

– TMS 2012 Annual Meeting and Exhibition,

2012, Orlando, Florida


Odenthal, H.-J.; Reifferscheid, M.;

Hovestädt, E.: Numerical study of improve-

ments of the flow simulation and the vessel

vibration in the AOD-process. STEELSIM, 4th

International Conference on Modelling and

Simulation of Metallurgical Processes in

Steelmaking, 2011, Düsseldorf, Germany

[42] Rückert, A.; Pfeifer, H.: Numerical investiga-

tions of multiphase flows in metallurgical

reactors using a discrete phase model. 2nd

ESTAD, 2015, Düsseldorf, Germany

[43] Giesselmann, N.; Rückert, A.; Pfeifer, H.;

Tewes, J.; Klöwer, J.: Coupling of multiple

numerical models to simulate electroslag

remelting process for Alloy 718. ISIJ Interna-

tional 55 (2015) No. 7, p. 1408-1415


Tewes, J.; Klöwer, J.: Simulation of solidifica-

tion and fluid flow behaviour in the ESR

process for industrial scale ingots. ICRF, 2nd

International Conference on Ingot Casting,

Rolling & Forging, 2014, Mailand, Italy

[45] Giesselmann, N.; Rückert, A.; Pfeifer, H.: Math-

ematical modelling of the momentum and

heat transfer in the electroslag remelting pro-

cess. STEELSIM, 4th International Conference

on Modelling and Simulation of Metallurgical

Processes in Steelmaking, 2011, Düsseldorf


Tewes, J.; Klöwer, J.: Numerical simulation of

the electroslag remelting process in order

to determine influencing parameters on

ingot defects. ICRF, 1st International Confer-

ence on Ingot Casting, Rolling and Forging,

2012, Aachen, Germany

[47] Rückert, A.; Pfeifer, H.: Mathematical model-

ling of the flow field, temperature distribu-

tion, melting and solidification in the elec-

troslag remelting process. Magnetohydro-

dynamics 45 (2009), No. 4, p. 527-533

[48] Rückert, A.; Pfeifer, H.: Mathematical model-

ling of the momentum and heat transfer in

the electroslag remelting process. STEEL-

SIM. 2nd International Conference Simula-

tion and Modelling of Metallurgical Pro-

cesses in Steelmaking, 2007, Graz/Seggau

[49] Eickhoff, M.; Giesselmann, N.; Rückert, A.;

Pfeifer, H.; Tewes, J.; Klöwer, J.: Introducing

an analytic approach on air gap formation

during the ESR / VAR process and numerical

validation. ICRF, 2nd International Confer-

ence on Ingot Casting, Rolling & Forging,

2014, Mailand, Italy

[50] Eickhoff, M.; Rückert, A.; Pfeifer, H.; Tewes, J.;

Klöwer, J.: Simulation of industrial scale VAR

process – heat transfer ingot to mould and vali-

dation. LMPC – LIQUID METAL PROCESSING &

CASTING CONFERENCE 2015, Leoben, Austria


Klöwer, J.: Measurement of emission coeffi-

cients for Alloy 718 to improve numerical sim-

ulation of industrial scale VAR process. STEEL-

SIM, 6th International Conference on Model-

ling and Simulation of Metallurgical Processes

in Steelmaking, 2015, Bardolino, Italy


Klöwer, J.: Modellierung von Strömung, Wärme-

haushalt und Erstarrung des VAR-Prozesses.

Jahrestreffen der ProcessNet-Fachgruppe

Hochtemperaturtechnik, 2016, Nürnberg

[53] Schubert, C.; Eickhoff, M.; Rückert, A.;

Pfeifer, H.: Modelling the vacuum arc

remelting process in rectangular geome-

tries. STEELSIM, 6th International Confer-

ence on Modelling and Simulation of Metal-

lurgical Processes in Steelmaking, 2015,

Bardolino, Italy

[54] Gültekin, R.; Rückert, A.; Pfeifer, H.: Numeri-

cal approach for the implementation of the

interaction of pyrolysis gases and combus-

tion products in an aluminium-melting fur-

nace. INFUB, 2017, Algarve, Portugal

[55] Gültekin, R.; Rückert, A.; Pfeifer, H.: Numeri-

cal approach for the implementation of the

interaction of pyrolysis gases and combus-

tion products. TMS, 2017, San Diego, USA

[56] Bruns, H.; Rückert, A.; Pfeifer, H.: Approach

for pyrolysis gas release modelling and its

potential for enhanced energy efficiency of

aluminium remelting furnaces. TMS, 2017,

San Diego, USA

[57] Bruns, H.; Gültekin, R.; Dittrich, R.; Rückert,

A.; Pfeifer, H.: Integration der Pyrolyse

poröser Medien in ANSYS Fluent. Jah-

restreffen der ProcessNet-Fachgruppe

Hochtemperaturtechnik, 2016, Nürnberg

[58] Gültekin, R.; Rückert, A.; Pfeifer, H.: Cou-

pling flameless combustion with thermal

decomposition. STEELSIM, 6th International

Conference on Modelling and Simulation of

Metallurgical Processes in Steelmaking,

2015, Bardolino, Italy

[59] Gültekin, R.; Rückert, A.; Pfeifer, H.: Cou-

pling flameless combustion with pyrolysis

reactions. ANSYS Konferenz & CADFEM

Users‘ Meeting, 2015, Bremen, Germany

Authors:Univ.-Prof. Dr.-Ing. Herbert Pfeifer, Dr.-Ing. Thomas Echterhof, Dr.-Ing. Antje Rück-ert, Dr.-Ing. Wolfgang Lenz, Christian Schwotzer, M.Sc. (Corresponding Author)

Contact:Institut für Industrieofenbau und Wärmetechnik (IOB) RWTH Aachen University Aachen Tel.: +49 (0)241 / 80-26068 [email protected] www.iob.rwth-aachen.de


Handbook of Thermoprocessing Technologies Volume 2: Plants | Components | Safety

Editors: Franz Beneke, Bernard Nacke, Herbert Pfeifer 2nd edition 2015Pages: 1 028 ISBN Book: 978-3-8027-2976-8Price: € 240,-ISBN eBook: 978-3-8027-3012-2Price: € 200,-

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Handbook of Thermoprocessing TechnologiesRequired Reading for Thermoprocess Engineers

Documents

Department for Industrial Furnaces and Heat Engineering of ... · material has been created over the years, which are partly summarized in the books “Taschenbuch Industrielle Wärmetechnik”