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

limited power inputs and the unit then produced very homogeneous-foamy glass. Later the
Micro Mixer was replaced with a more satisfactory holding tank, 24 in. wide by 24 in. deep by
66 in., with sidewall electrodes for temperature adjustment and heat losses. The output was a
homogeneous seedy glass.
• The Centrifugal Refiner was designed to remove seeds and bubbles rapidly from the glass
without using chemical refining agents. The normal bubble rise that results from density
differences between the glass and the gas bubble is directly proportional to the gravitational
force, normally 1G. The G force enhancement by means of a centrifuge offered the most
potential for rapid seed removal.
The Centrifiner’s vertical axis inlet and outlet was operated with a 14 in. diameter, which had
been designed for a 24 in. diameter hot zone. The inner chamber was about 4-feet long with inlet
and outlets about 1.5 feet long. Heat losses caused temperature drops of 100 to 150˚F in the glass
and were dependent on pull rate. The unit was tested at a maximum temperature of 2600˚F
(1427˚ C). A platinum slinger placed in the top inlet caused the inlet stream to move horizontally
to the top wall of the unit. A platinum diverter plate was located near the bottom, with holes
located at the wall to allow glass with high G-force, time histories to move to the bottom exit
tube. A stationary spindle decelerated the spinning glass column and moved vertically to control
the flow rate.
Seed removal was controlled by rotational speed, viscosity (temperature), time (pull rate), and
seed size. Seeds above a certain size are removed and smaller seeds pass through. The operating
design parameters were selected to remove seeds above the normal minimum of about 0.004 in.
at flow rates up to 19 tons/day. When operated at normal speed of 1100RPM, 240 G forces
developed at the 14 in. diameter. (Richards, Ray S., “Rapid Glass Melting and Refining System,”
Advances in the Fusion of Glass, American Ceramic Society: Westerville, OH, 50.1-50.11
(1988))
Table IV.I. RAMAR compared to conventional melting systems.
Standard Furnace RAMAR
30 hr. Mean Resident Time 20 Times Faster
Mixing–8 ft. per hr. 2000 Times Faster
Heat Transfer by Radiation/Convection Direct Electric–100 Times Faster
2900 ˚F (1593˚C) Peak Temperature 2500 ˚ F (1371 ˚ C) Little Refining Agent
NOx Pollution No NOx Pollution
SO2 Pollution No SO2 Pollution
Bubble-See Rise-1/2 ft. per hr. 240 Times Taster
Large Furnace Size 20 Times Smaller
Owens-Illinois did not move into production scaleup because of technical limitations associated
with the centrifigual refining device. The 12-ton capacity of the RAMAR was insufficient to
serve a typical IS machine that requires an 80 ton capacity.
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