Aluminium_Insight_20.. - Pyrotek

July 2012 Volume 6, Issue 2Pyrotek launches automatic heating system for laundersPyrotek offers a proven automatic heating technology designedfor launder and filter box applications. Mark Vincent,European R&D Project Manager, UK, outlines this technology,along with its design and process benefits.The purpose of the technology is to improve metal quality byeliminating thermal loss which occurs when liquid metalcomes in direct contact with the hot-face refractory. This isespecially prevalent in the early stages of a casting campaign.Traditional PreHeatingTechniquesIn a typical situation, prior to casting, the hot-face refractorymaterial is preheated to store energy as evenly as possible.This helps reduce any negative thermal effect on the moltenaluminium as it makes contact with the refractory. Preheatingis often achieved with the use of lid-mounted energysources, such as electrical resistance, gas flame or hot air.During the early stages of a casting campaign heat energy cancontinue to be absorbed and lost by the refractory from theflowing molten aluminium. The extent of this on-going lossdepends on many factors such as the efficiency of the initialpreheating, refractory mass, thermal conductivity, flow rate,and backup insulation efficiency. Figure 1 shows the generalarrangement of the heated launder system.This system ensures efficient replacement of worn sectionsand provides excellent protection to the heating system. Thesafety lining is designed to transfer energy from the heatingsystem around the two vertical sides and the base, ensuringthe entire hot-face refractory is thermally soaked.To minimise energy consumption during inactive periods, aset of specially fabricated covers are manufactured for eachindividual system that prevent continual heat loss into theatmosphere, and keep the refractory at a uniform temperatureto minimise process costs.Fig. 2–Automatic Heated Launder SystemFig. 1–Heated Launder SystemAutomatic Heated LaunderSystemIn the Pyrotek Automatic Heated Launder System, the hot-facerefractory is contained within a protective safety lining andinner metallic shell known as a “cartridge.”During casting, internal covers are removed and replacedwith top covers to help further increase the thermal stability.The system works to continuously maintain the chosen hotfacerefractory setpoint.Process BenefitsThe Pyrotek Automatic Heated Launder System offers a rangeof process benefits:• It can help resolve issues in both batch and continuouscasting, depending on considerations such as plant layoutand humidity.• It allows for complete elimination of traditional preheatingpractices as the refractory is held consistently at a settemperature.

• Minimal metal temperature loss providing excellent andrepeatable thermal consistency.• The design allows static molten metal to be held in therefractory trough as required, a useful feature in somecircumstances.• Individually controlled temperature zones of hot-face refractoryallow further flexibility.• Holding furnace temperatures can be reduced, resulting insignificant energy savings.• Since the refractory is held at near molten metal temperature,thermal shock and cycling fatigue are not issues, sodenser, metal-resistant refractory materials can be used,extending refractory service life.• A significant reduction in both joint and coating maintenanceis realised.Currently Pyrotek has two heated launder systems in operationon continuous sheet casting lines. Additionally, thetechnology is available to the Alcan Compact Degasser(ACD) units, of which six have been in operation for morethan one year.Case StudyOne customer purchased a Pyrotek heated launder systemwith integrated filtering and immediately realised the operationalbenefits. Metal quality was excellent with no oxidegeneration due to the indirect heating system, and consistentmolten metal temperature was maintained along the entireline. The holding furnace temperature was reduced by 22°C(72°F), and casting campaigns in excess of 20 days are nowrealised. The system has been in service for over two years,and the original refractory is in good condition. As a resultthe client has now commissioned a second system whichreflects the success of Pyrotek’s technology.Pyrotek is now accepting commercial enquires for this technologyafter the success of industrial testing over the pasttwo years.www.pyrotek.info/launder