Gas Fired Holding Furnace Modeling for Efficient Operation

Much work has been done to improve the melting process in the secondary aluminum industry. Technologies such as regenerative burners, recuperative burners, stack melters, and multi-chamber furnaces have greatly improved energy efficiency. These technologies are expensive and are difficult to cost justify for other portions of the process within the plant. In particular, holding furnaces are frequently ignored in energy programs due to the relatively low natural gas usage. However, after melting furnaces are upgraded, it makes sense to examine the holding furnace and investigate lower cost upgrades to reduce energy usage. In this paper, different options, e.g. gas flow rates at high and low fires and burner allocation, have been modeled to improve energy use. The results indicated a significant furnace performance improvement by changing the gas flow ratio between the two burners while they operate on high fire mode. Similar results are obtained when the distance between the two burners are increased. The performance enhancement indicates a significant gas saving in the furnace under investigation.