Glass Melting Technology: A Technical and Economic ... - OSTI

Special energy consumption, normalized to 50 percent cullet in the batch and primary
energy equivalents, increased on average with 0.8–0.9 percent per year of age for the 123
investigated glass furnaces. This means that during five to 14 years of furnace lifetime,
energy consumption may increase by seven to 10 percent due to refractory wear, which
causes greater wall heat losses, air leakage, insulation wear, or plugging and fouling of
regenerators. For large end port regenerative and recuperative LoNOx melters with cullet
preheaters that use 70 percent cullet, energy consumption levels were about 3.7–3.8
mmBt/short ton (normalized to 50 percent cullet).
The Sankey diagram (Figure I.3.) of energy flows in the most energy-efficient container
glass furnace—cross-fired regenerative furnace without electric boosting—75 percent
cullet, with batch preheating. About 49 percent of the energy input was used for heating
the glass and the fusion reactions. Glass melt energy represents sensible heat of the glass
at throat temperature.
Figure I.3. Crossfired regenerative 70-75% cullet and batch preheat Sankey diagram from
Ruud Beerkens, TNO; represents one of the 10% most energy efficient furnaces
(container glass) in Europe
The general consensus of European glass manufacturers is that batch preheating can
potentially decrease specific energy consumption by about 10 to 15 percent. By
increasing cullet for raw material by 10 percent, energy input requirements could be
reduced by 2 to 5 percent. As the lining of the furnace deteriorates with age, energy input
requirements can increase by 0.1–0.2 percent per month.
I.3.3. Operating costs for capital productivity
With few new glass plants being built in the US over the past few years and additional
production needed to meet market demand, glass manufacturers have attempted to
increase productivity by increasing output from established furnaces. Since space in
most glass plant facilities is limited, the possibilities for expansion of furnace size are
limited, and capital cost to build new furnaces is high. Manufacturers may choose to
accept the extra cost of melting per ton of glass by increasing production with electric
boosting of fossil fuel or adapting to oxygen firing.
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