Papers by Keyword: Furnace Design

Abstract: A set of single crystal growth experiments was performed in the new resistively heated two-heater furnace, which plays the role of an induction furnace with a moving coil. In this new experimental setup we are able to control the shape of the crystallization front, from flat to extremely convex. The positive results of the experimental tests differ significantly from prior discouraging interpretation of computational modeling results obtained by a commonly used software, previously presented in the literature. The essence of a new regulation of the temperature field during the crystal growth is a displacement of the maximum of the temperature field, which at the beginning of the growth is located close to the seed and it moves towards the source material as the crystal length increases. In this way, the crystallization front is heated with a similar intensity regardless the increasing crystal length.

Abstract: This paper outlines various aluminium melting furnaces arrangement alternatives and their related benefits as well as the physical and practical challenges of the aluminium melting process using fuel fired reverberatory furnaces. Performance comparisons are made between dry hearth and wet hearth furnaces to highlight the benefits of dry hearth melting as well as the impact of melting practice on ultimate equipment performance. Both single chamber and twin chamber dry hearth furnaces are described in various configurations including the unique benefits of each design.

Abstract: Mathematical modelling is reaching a high acceptance level within the glass industry. Today most new furnaces are being modelled before the final design is decided. It is clear that the modelling helps to optimise the furnace in respect to glass quality, energy efficiency and furnace life-time. The extra effort of the modelling is leading for sure to a quick pay-back of this extra investment and an increased profit over the furnace life-time. Even the furnace life-time can be extended with better insight on temperature distribution and glass speeds that corrode the refractory. Many glass produces are always asking us: “what is the optimal glass depth” There is not just one answer to this, but the paper demonstrates how mathematical modelling can help to find the optimal furnace depth for a certain furnace design.

Abstract: This paper covers the experiences of the authors based on the studies and developments made within the company over the years, where improvements on furnace design have always been a major issue. Developments have been achieved by driving forces like requirements for higher glass quality, different products, and increased number of product changes, energy efficiencies, lower investment cost and environmental challenges. Although in the glass world today there are studies and projects to develop different radical melting techniques, like plasma melting, submerged combustion, segmented melter and vacuum refiners being the most promising among the many, the progress going from pilot to full scale is slow and not all the glass manufacturers are giving enough funds to support these projects. Even though the conventional furnace technology is quite mature and energy performances of the most energy efficient furnaces [1] and pull rates are approaching near to the limits, there are still differences between the energy consumptions, pull rates and life of furnaces in glass industry today. Many small steps can be taken at different areas like optimizing furnace design criteria, refractory selection, use of additional equipments, and development of sensors, better combustion equipment, advanced control systems. These all add to continuous incremental developments for each project and give us opportunity to progress with feedback from onsite applications.

Abstract: The ability to set and accurately control the desired growth conditions is crucial in order to attain high quality bulk growth of Silicon Carbide (SiC), especially when the ingot size is large (> 2” in diameter by > 2” long). However, these two aspects of SiC PVT (Physical Vapor Transport) growth technology are severely limited in “conventional” SiC PVT growth reactors with single cylindrical heaters. To overcome such shortcomings, an “alternative” furnace design with two plane resistive heaters is proposed. In order to verify benefits of this design, numerical modeling and comparative procedures have been employed. Detailed comparative analysis revealed two fundamental disadvantages of the conventional furnace design, attributed to (a) – significantly higher in magnitude and spatially nonuniform distribution of the thermal stress that consequently deteriorates structural quality of the growing SiC boule, and (b) – inability to grow long (> 2”) monocrystalline ingots of SiC. Furthermore, the potential of the alternative furnace design to overcome fundamental limitations of the conventional design is also analyzed, with particular attention being paid to the processes of source material recrystallization.