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

• electrostatic collection is efficient;
• batch moisture is at a maximum.
BOC has been scaling up efforts to confirm the applicability of combining preheating of batch
and cullet with furnace exhaust gases to collect particulate and acid gases. Development of the
technology has been hampered by insufficient funding, scale-up, reliability and limited glass
composition. E-Batch technology offers a simple and low-cost means of melting glass for
conventional air-fuel furnaces that are fitted with air-pollution control systems.
IV.8.2. Nienburger Glas Batch Preheater (1987)
Of all the preheating technologies explored, the Nienburger Glas Batch Preheater has been the
most successful. In this system, furnace exhaust gases and a batch and cullet mixture are in direct
contact inside a hopper. In the five installations in German glass facilities, furnace energy
savings of up to 29 percent were reported.
The heat content of hot waste gases from the melting furnace directly heats the raw materials,
batch and recycled cullet together in the preheater. Recycling waste heat back to the furnace is a
very effective way to conserve energy in the glass melting process. The waste gases flow through
the material in a rectangular mixed batch storage bin in which several levels of channels are open
on the bottom. Inside a hopper, furnace exhaust gases and a batch and cullet mixture are in direct
contact.
All raw materials are weighed and mixed prior to delivery to the preheater device. Located
directly above the batch charger, this device acts as the mixed batch storage bin for the melting
furnace. The hot flue gas from the furnace travels up through several layers of open-bottom ducts
in a counter flow configuration relative to the batch being drawn downward as it is fed into the
furnace. During the process, the alkaline components in the batch partially neutralize acidic
gases in the waste gas stream.
Started up in December 1987, the first Nienburger batch preheater operated continuously for a
1.2 million tonne campaign (“tonne” refers to a metric ton [1000 kg], as opposed to a “ton” or
“short ton,” 2000 lbs.; therefore 1 tonne = 1.1 ton).
In March 1991, a second unit was installed on a new 330 tonne/day furnace and has remained on
line over 99 percent of the time. In 1992, a third unit was commissioned as a greenfield furnace.
It started up in August 1995 with a 400 tonne/day batch preheater and a McGill electrostatic
precipitator.
In February 1997, a “Gerresheim” oxy-fuel converted furnace was then built with a preheater,
incorporating the design as developed during the previous installations. Using the Nienburger
Glass process, batch preheating results in a certain amount of batch-dust carryover from the
direct contact between the hot flue gases and the batch. A downstream electrostatic precipitator
must be used to capture this fugitive dust as well as the fine particulate from the furnace.
Although the Nienburger Glas batch preheater cannot be considered a particulate control device,
it does reduce the emission of SOx, HCl, HF, as well as selenium from flint glass.
77