Oxygen-enriched and oxyfuel furnaces are used
in specialty glass operations to reduce emissions
or to make possible higher production rates with
the same size furnace. Although oxyfuel furnaces
may produce higher NOx emissions on a concen-
tration basis, they are expected to yield very low
levels of nitrogen oxides on a mass basis (kg/t of
product). Low-NOx furnaces, staged firing, and
flue gas recirculation are available to reduce both
concentration and the mass of nitrogen oxide
emissions. These techniques are also available for
air-fuel-fired furnaces. Nitrogen oxide levels can
be controlled to 500–800 milligrams per cubic
meter (mg/m3).
The type of combustion fuel used affects the
amount of sulfur oxides and nitrogen oxides
emitted. Use of natural gas results in negligible
sulfur dioxide emissions from the fuel compared
with high-sulfur fuel oils. Fuel oil with a low sul-
fur content is preferable to fuel oil with a high
sulfur content if natural gas is not available.
An efficient furnace design will reduce gaseous
emissions and energy consumption. Examples of
improvements include modifications to the
burner design and firing patterns, higher
preheater temperatures, preheating of raw ma-
terial, and electric melting.
Changing the composition of the raw materi-
als can, for example, reduce chlorides, fluorides,
and sulfates used in certain specialty glasses. The
use of outside-sourced cullet and recycled glass
(SCR), selective noncatalytic reduction (SNCR),
and certain proprietary processes such as the
Pilkington 3R process.
Sources
Bounicore, Anthony J., and Wayne T. Davis, eds. 1992.
Air Pollution Engineering Manual. New York: Van
Nostrand Reinhold.
Economopoulos, Alexander P. 1993. Assessment of
Sources of Air, Water, and Land Pollution: A Guide to
Rapid Source Inventory Techniques and Their Use in
Formulating Environmental Control Strategies. Part 1:
Rapid Inventory Techniques in Environmental Pollution.
Geneva, World Health Organization.
Sittig, Marshall. 1975. Pollution Control in the Asbestos,
Cement, Glass, and Allied Mineral Industries. Park
Ridge, N.J.: Noyes Data Corporation.
World Bank. 1996. “Pollution Prevention and Abatement:
Glass Manufacturing Plants.” Draft Technical Back-
ground Document. Environment Department, Wash-
ington, D.C.
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