Page 125 - Wastewater Solids Incineration Systems

Combustion Technology 93

beneficially reusable glass aggregate product. The process train comprises the melter, a
heat exchanger, the air cleanup system, and an exhaust recycle fan (Figure 5.18).
The closed-loop oxygen enhanced process uses pure oxygen (greater than 90%)
injection as the source of oxidizer, eliminating use of atmospheric air and, therefore,
the ballast and diluent nitrogen. The melter, composed of separate but interconnected
refractory lined chambers surrounded by a water jacket to dissipate heat lost, pro-
vides a three-zone operation. Feedstock that has been predried to at least 85% solids
or greater is injected along with synthetic air to the zone 1 chamber. In this zone, the
organic component of the feedstock is completely combusted, liberating a significant
amount of heat energy and resulting in temperatures between 1315 and 1482°C (2400
and 2700°F). At these high temperatures, the mineral (ash) component of the feed-
stock melts to form a pool of molten glass at the bottom of the zone 1 chamber.
Phase separation of the molten glass and exhaust gas occurs by gravity draining
the molten glass from zone 1 through a drain port on the bottom of the zone 2
chamber. The molten material drops into a water quench tank and is cooled into the
glass aggregate product. Hot combustion gases are directed out of zone 2 through a
refractory-lined duct to zone 3. Hot exhaust gas is cooled through dilution mixing
with lower temperature gases obtained by the recirculation of cooled exhaust gas.

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FIGURE 5.18 The GLASSPACK closed-loop oxygen enhanced vitrification process
(courtesy of Minergy Vitrification LLC).