Vessel Erosion allowance should be factored into the hold vessel design,
based on the feed material and the mixing system potential to abrade the tank
Feed to Melter . Like the sampling system, the melter feed system moves
homogeneous feed from the hold tank to the melter. Also as noted earlier,
selecting a pumping system similar to the one from the sampling system will
provide some degree of consistency between the samples and the actual feed
to the melter. The feed system should consider the need for flushing and
plug-clearing capabilities, particularly at the melter discharge point.
Experience has shown the potential for high temperatures to dry out and
accumulate feed material at this point.
Acceptable Glass Compositions . Acceptable glass compositions with
respect to melter behavior are those compositions exhibiting properties
amenable to proper melter operation and longevity. These properties include
glass viscosity at operating temperature, liquidous temperature, glass
electrical resistivity at operating temperature, and glass transition temperature.
The actual values for these parameters depend on the melter technology
employed. In addition, the following compositions should be avoided: those
that exhibit behaviors such as foaming in either the cold cap during drying or
in the glass melt pool and those with unfavorable Redox behavior (i.e.,
precipitation of metals during melting) or explosive gas generation (i.e.,
Acceptable glass properties and behaviors should be generally identified early
in the project and promulgated through the process development phase.
Melters and Melter Behavior . Melters vary in size, configuration, and heating
source. The large-scale, high-level waste melters in the DOE system are joule
heated, by passing current through the actual glass melt. RF and gas-fired
melters have also been proposed. The melter' configuration usually requires
The first is a refractory chamber surrounding a glass melt " ool,"where some
mixing occurs either by natural convection or as enhanced with air bubblers;