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

meeting business cycle demands and rebuild time is short. The use of colorant fore hearths is
another attempt to gain more flexibility and greater capital productivity. Smaller-volume electric
melters, such as the Pochet melter, have a much shorter life, but can be rebuilt in less time and at
a much lower cost.
Production costs
The financial picture of glass production can be greatly affected by site-specific factors, such as
prevailing energy costs, product quality requirements, available space, costs of alternative
abatement measurements, prevailing legislation, ease of operation, and the anticipated operating
life of alternative furnaces. In regions where the difference between the cost of fossil fuel and
electricity is at the upper end of the range given, electric melting may be a less attractive option.
To influence glass-manufacturing costs, any new melting technology must reduce both energy
needed for melting and amortized furnace costs. Avoiding or reducing costs of air emissions
controls can substantially reduce operating costs.
Conventional glass melters reflect industry segment and site-specific differences that contribute
to the net cost of delivering glass to a production-forming operation. The cost of producing glass
comes from costs of raw material freight, purchased cullet, energy (natural gas, oil, electricity),
and furnace construction design. Container batch costs, for example, are typically $38 to 65 per
ton as compared to wool fiberglass batch costs of $90 to 110 per ton. Furnace energy and
rebuild costs can vary even more broadly. Operation costs of some all-electric melters can
exceed $55 per ton, and amortized furnace costs can be as much as $10 per ton. (See Table II.11
as an example of accumulated costs in the container glass segment.)
Table II.11. Direct Costs of Molten Container Glass Delivered to Fabricator
Average ($/ton) Range ($/ton)
Batch raw material costs 50.00 38–65
Batching labor operations 1.50 0.75–3.00
Amortized batching equipment 1.00 0.25–2.50
Amortized furnace equipment 6.00 2.50–8.00
Melting energy costs 25.00 16.00–35.00
Melting labor operations 1.50 0.75–3.00
Particulate emission control 1.00 0.25–4.00
Total molten container glass cost delivered to
fabricator
86.00
Feasibility of electric furnaces
Electric furnaces have much lower capital costs than conventional furnaces, which when
annualized partially compensate for their higher operating costs. Electric furnaces have shorter
campaign lives and may require rebuild or repair in two to six years, compared to five to 14
years for conventional furnaces. For small air-fuel conventional furnaces (up to about 100 tpd),
heat losses are relatively high compared to larger furnaces. In the range of 15 to 100 tpd, electric
furnaces have lower heat losses than air-fuel furnaces. Electric furnaces are thermally efficient,
two to four times better than air-fuel furnaces, and can be more competitive than air-fueled
furnaces.
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