Holding furnace

Process Description

Many aluminum alloys require melt pool cleaning in order to eliminate unwanted accompanying elements and to homogenise and degas.  Holding furnaces or specially designed rinsing stations are used for this purpose. The holding furnaces are usually chamber furnaces and depending on the application can be round or rectangular, tiltable or stationary and with one or more chambers, usually with bottom purging systems. 

Aluminum holding furnace

Gas Application

Particularly efficient cleaning takes place by introduction of an inert gas into the melt. In the case of holding ovens, bottom purging is preferably used. This is a feeding system made of a porous material, which is arranged in the bottom of the melting vessel, and from which the gas ascends in the melt in the form of fine bubbles. Accompanying substances are entrained by the ascending gas bubbles and accumulate as slag on the surface of the melt. An additional positive effect is a homogenisation of the molten bath through the constant motion resulting from the ascending gas bubbles.    

To ensure that the temperature of the melt remains constant, burner systems are also installed in the holding furnaces. Combustion with oxygen (oxyfuel), possibly in combination with flue gas recirculation or combustion with oxygen-enriched air, reduces the fuel consumption and increases the economic efficiency of the process.   

Advantages of Oxyfuel burner systems at a glance:

• Higher combustion efficiency
• Higher melting rate
• Faster heating-up times
• Lower fuel consumption
• Higher processing temperatures possible
• Faster reaction speeds
• Lower exhaust gas levels
• Less dust
• Lower emissions
• Lower production costs

Messer Solution

In addition to the gases required for your process, Messer offers a variety of equipment for its optimisation under the brand names Oxipyr and Oxijet. In order to select the optimum system, experts from Messer first carry out a comprehensive process analysis. Following calculations and basic engineering, suggestions are made for optimisation and further procedures. 

Oxipyr – Air flame inside a holding furnace

Oxipyr – Burner Technology

The characteristics of the burner types are multi-faceted and range from low to high momentum burners, oxyfuel to oxygen/air mixing burners and burners for different fuels or fuel combinations. The systems are controlled manually, semi- or fully automatically following compositions or temperature.  

Bottom Purging Technology

Messer only offers complete solutions for bottom purging systems in cooperation with partners.  

Porous plugs and Oxipyr-Air