Design Considerations in High-Temperature Devices include methods to
accommodate the expansion and movement of materials during heat-up, the
possibility of auxiliary cooling of the outer structural shell, selection of
materials for low expansion coefficients, and the selection of materials for
corrosive resistance at operating temperatures the component will actually
Penetrations/Sleeves through the melter shell will usually encounter the
largest temperature differentials during normal operation. Special
consideration should be afforded the selection of materials for corrosive-
resistant properties and strength characteristics at the operating temperatures
involved. In some cases, the use of a sacrificial inner liner material may be
worthwhile, keeping in mind that the details of remote replacement of the
component will have to be a part of the design.
Warping and Alignments are critical concerns in melter design. Because of
the operating temperatures involved, materials are going to distort. Selection
of materials, innovative use of refractories, and the ability to cool areas of the
melter that are not integral to the glass melting function can be used to
minimize warping. Movement of materials during heat-up is a reality that
should be factored into the design.
Off-Gas Processing . Off-gas from melter- and canister-filling operations
should be processed through some type of off-gas collection and treatment
system. The collection portion of typical systems includes a ducted suction
arrangement to maintain a slightly negative pressure on the melter " ool"
chamber and the discharge cavity, which in turn interfaces with the canister
filling operation. The amount of actual airflow from these areas should be
balanced against loss of heat from both melter chambers and effects on the
glass discharge stream while maintaining adequate collection of the off-gas
stream. For example, excess airflow from the discharge chamber can affect
the glass pour stream by causing wavering, a less viscose glass stream, and
the formation of glass " ird nests"in the canisters being filled.