Influence of the natural aluminium oxide layer on ... - ALU-WEB.DE

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MELTING, RECYCLING & HEAT TREATMENT center <strong>of</strong> <strong>the</strong> casting. Energy consumption and process efficiency between 55°C and 535°C • not coated: heating time = 0.27 h • E = 36.63 x 0.27 = 9.89 kWh • η = 3.579 7 /9.89 = 0.361 • coated: heating time = 0.2 h • E = 36.63 x 0.2 = 7.3 kWh • η = 3.579 8 /7.3 = 0.49 surface heating rate [°C/s] coated 0.59 not coated 0.68 Tab. 1: <strong>Influence</strong> <strong>of</strong> surface Gas fired burners The following experiment was strongly supported by LOI Italimpianti and performed by Elster Kromschröder. Experiment purpose – determination <strong>of</strong>: • heating rate (furnace preheated at ~ 500°C) Experimental conditions: • experimental heat treatment furnace using a ceramic flat flame burner as infrared radiation source power : 450 kW • test specimen die casting: cylinder head Al-Si-Mg-Cu alloy weight: 26 kg wall thickness: 120 mm • exposure to radiation unilateral Fig. 2: Flat flame burner: 450 kW Conclusion and prospects The industrial use <strong>of</strong> <strong>the</strong> infrared radiation for <strong>the</strong> heat treatment <strong>of</strong> aluminum castings in Europe is only a question <strong>of</strong> time. 808 7 Q = ⎯⎯ 26 x ∫(4.8 + 3.2 . 10-3T)dT = 3075.44kcal = 3.579kWh 26.9 328 808 8 Q = ⎯⎯ 26 x ∫(4.8 + 3.2 . 10-3T)dT = 3075.44kcal = 3.579kWh 26.9 328 Fig. 3: Heating rate: 450 kW Belte’s industrial concept is illustrated in Fig. 4. Our concept proves that <strong>the</strong> next generation <strong>of</strong> <strong>aluminium</strong> heat treatment plants will be: • extreme mobile commissioning/decommissioning duration: ~ three weeks • extreme flexible without base and ancillary frames • extreme short processing time • extreme environmentally friendly without gas emission (in <strong>the</strong> case <strong>of</strong> <strong>the</strong> use <strong>of</strong> electric radiant burners) References [1] http://www.britannica.com/ [2] M. Wagner, P. Buchet, W. Kesteleyn, A. Molin – Radiant heating in industrial processes, 22nd World Gas Conference June 1-5, 2003 Tokyo, Japan Fig. 4: Industrial infrared heating facility for <strong>aluminium</strong> alloys [3] C. Samoila, L. Druga, L.Stan – Cuptoare si Instalatii de Incalzire, EDP, Bukarest, 1983 [4] D. Dragulin, M. Belte, M. Dragulin – Thermodynamische Aspekte der Wärmebehandlung von Metallen, pro Business Verlag, Berlin, 2010 [5] M. Orfeuil – Electric Process Heating, Battelle Press, 1987 [6] J. H. Brunklaus – Cuptoare Industriale, Editura Technica, Bukarest, 1977 [7] A. Schack – der industrielle Wärmeübergang, 5. Auflage, Stahl-Eisen Verlag, 1957 Authors Markus Belte is CEO <strong>of</strong> <strong>the</strong> Belte AG, located in Delbrück, Germany. Dr. Dan Dragulin is head <strong>of</strong> research and development at Belte AG. 62 ALUMINIUM · EAC CONGRESS 2011
Abbildungen: promeos Resource efficiency at increased process quality becomes <strong>the</strong> dominating driver for investments in industry, and so in <strong>the</strong> world <strong>of</strong> casting. An optimized melting and material logis- tics process requires optimum temperature control <strong>of</strong> material and casting equipment, including melting furnace, transportation ladles or launders and casting moulds. MELTING, RECYCLING & HEAT TREATMENT New standards in gas-fired heating <strong>of</strong> moulds, ladles, launders and melting furnaces through flameless burner technology Jochen Volkert, promeos GmbH Fig.1: Porous burner Fig. 2: Different designs <strong>of</strong> <strong>the</strong> porous burner Based on its flameless high performance industry burner portfolio, promeos <strong>of</strong>fers new preheating and tempering solutions all along <strong>the</strong> process line. Energy savings <strong>of</strong> up to 75% and increased process stability due to enhanced control measures have been approved at numerous foundries all across <strong>the</strong> metal processing market. The clou is as easy as impressing: <strong>the</strong> absence <strong>of</strong> a free flame as spot-type heating source and <strong>the</strong> infinitely adjustable heat flux (similar to a dimming lamp) are core features to avoid inhomogeneity and inefficiency in heating ladles, launders or moulds. Porous burner technology In a porous burner (Fig. 1) <strong>the</strong> combustion takes place in a porous high temperature ceramic, <strong>the</strong> combustion reactor, instead <strong>of</strong> in an open flame. This results in a flameless, volumetric combustion in <strong>the</strong> form <strong>of</strong> glowing ceramic foam which can be used as a radiating surface as well as a homogenous source <strong>of</strong> heat. Any shapes are possible such as round or square burners, lines, cylinders, rings, rhombuses and o<strong>the</strong>r specially tailored shapes (Fig. 2). Special applications require special solutions, for example line shaped burner heads Table 1: Heating systems for casting moulds: benefits / value proposition which concentrate <strong>the</strong> heat from convection and radiation exactly where it is needed. The length <strong>of</strong> a reactor can thus be extended if desired. Dimensions <strong>of</strong> several meters in length with a reactor width from 15 to 200 mm allow specific burning performances from 2 to 600 kW/m in length. Based on <strong>the</strong> unique features <strong>of</strong> <strong>the</strong> flameless porous burner combustion technology, promeos develops and manufactures tailored heating systems for process applications. Furnace engineering is required for both process technology and manufacturing to ensure optimum product quality. The outstanding design features <strong>of</strong> promeos burners and its ease <strong>of</strong> integration into any kind <strong>of</strong> apparatus allow <strong>the</strong> heat to be distributed over / into <strong>the</strong> required area / volume and applied where <strong>the</strong> process needs it, as opposed to being directed to only one spot. promeos supplies ‘tailor made suits’ for your individual needs, powerful and efficient. The unique combination <strong>of</strong> features like <strong>the</strong> power density, a rapid and precise power adjustment (similar to electric heating devices), a homogeneous heat flux and its compact and modular design result in <strong>the</strong> following benefits: • enhanced quality <strong>of</strong> your products + reduced preheating times The high energy density and heat transfer via infrared radiation and controlled convention allow an unmatched quick heating <strong>of</strong> <strong>the</strong> moulds. Generally <strong>the</strong> preheating times are cut down 50% and more. + homogeneous temperature distribution So called ‘hot spots’ that are due to local fire or flames are completely eliminated because <strong>of</strong> <strong>the</strong> homogeneity <strong>of</strong> <strong>the</strong> heat input. In combination with <strong>the</strong> continuously variable power control <strong>of</strong> <strong>the</strong> burners <strong>the</strong> preheating <strong>of</strong> <strong>the</strong> mould can be controlled optimally. + production time Production time is gained due to <strong>the</strong> shortened heating-up time and corresponding process control. + less scrap production The ideal preheating <strong>of</strong> <strong>the</strong> mould reduces <strong>the</strong> number <strong>of</strong> required ‘warm castings’ – waste reduction is <strong>the</strong> consequence. + durability <strong>of</strong> <strong>the</strong> tools The homogeneous temperature distribution reduces <strong>the</strong>rmal stress and <strong>the</strong>reby automatically increases <strong>the</strong> lifetime <strong>of</strong> <strong>the</strong> tools. Σ ROI < 24 months, guaranteed < 12 months, mostly Usually your investment is recovered within a period <strong>of</strong> max. 12 months. We will compile you with a detailed amortization calculation with every <strong>of</strong>fer you receive from us. ALUMINIUM · EAC CONGRESS 2011 63
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