Microsoft Word 2012, Källén, M.,-Energy Efficiency Opportunities within the Heat Treatment Industry

5.3.2  Insulation 

The surface temperatures of the furnaces were investigated and all the main furnaces in the 

large line had one area with very high surface temperature. When the door between the 

heating chamber and the quenching chamber is opened, it is elevated into a hood which is not 

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as insulated as the heating chamber. The surface of the door hood had a temperature of 80-

160°C for furnace 120 – 126. The area with high temperature was estimated to 3m² for each 

furnace. If additional external insulation was attached to these high temperature areas, the 

electricity consumption in the furnaces could be decreased. If, for example, a 0.08m thick 

insulation weave was attached to the hoods on all main furnaces in the large line, the energy 

consumption in these furnaces would decrease with 108.7 MWh/year. See section 2.6 for the 

equations used for these calculations.