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

.) Develop new products by coupling work with continued research into how
surface coatings and other surface modifications can change or enhance the product:
create synergy toward new value-added glass that ensures adequate capital regeneration.
• High-intensity melter
All individual glass processes should be explored starting with creation of a highintensity
melting. In a higher temperature system, minerals can be substituted that contain
the oxides of B2O3, Li2O, K2O, Na2O rather than the more toxic and higher cost
chemicals. Higher temperature melting systems that do not need B2O3 or alkali oxides
Na2O, K2O, and Li2O in their formulations would be a quick way to reduce emissions.
Not all problems can be solved by substituting batch chemical constituents, but
technologies that avoid emission of dioxins from combustion would be desirable.
Refractory materials that allow higher melting temperatures without excessive corrosion
or blistering should be developed.
• Forced convection melting systems
More robust melters are required to control convection patterns by using a stirred
chemical reactor to control stirring forces that overwhelm convection created by thermal
and compositional gradients and by gas release. Natural convection in present glass
melters is very “fragile” and strongly affected by minor changes in inputs that cause
major changes in product quality. These bubbler, mechanical melter design systems allow
faster glass composition changes and lower residence time [Owens-Illinois RAMAR
features mechanically stirred melter and centrifugal finer system and contains some
essential features for future melters.]
• Preheating batch
By preheating batch, the batch layer can be thinned and extended, and dispersed into the
glass. Convection is increased and heat transfer is higher. These goals can be
accomplished by extending the heating portion of the furnace; mixing batch with glass by
submerged feeding and stirring, submerged combustion, mechanical stirring; reducing
bubble layer under the batch blanket; and recovering waste heat. The problem to
overcome in batch heating is to remove the bubble layer so as to increase the radiation
heat transfer to the melt.
• Oxy-fuel conversions
Oxy-fuel technology is thermally efficient and cost effective when the total system is
considered and up to three repair cycles that include the increased savings in regenerator
repairs and avoid recycling of toxic materials. Additional thermal energy is applied above
the batch charge or within the molten glass to drive basic mechanisms in a continuous
glass furnace. Oxy-firing is the best way to enable glass producers to meet restrictive
NOx emission legislation. Being relatively low-risk, it is nearly identical to traditional
glass-unit melters. Oxy-fuel furnaces allow precise thermal input for controlling the
melting process. Rebuild requires less refractory, and the furnace can be returned to
operation in a shorter time. Oxy-fuel furnaces are less expensive to construct than
conventional furnaces due to elimination of refractory and steel required for regenerator
92