Glass - Back to the Future!



Presenting Author:
Pavel Hrma
<Pavel.Hrma@pnnl.gov>

article posted 09 Jan 2016


Pavel Hrma Pavel Hrma is a scientist emeritus at the Pacific Northwest National Laboratory, Richland, Washington.






Feed-to-melt conversion process

Pavel Hrmaa*, Derek R. Dixona, Seungmin Leea,
Bradley R. VanderVeera, Benjamin P. McCartya,
Carmen P. Rodrigueza, Jaehun Chuna, Richard Pokornyb,
Tetsuji Yanoc, Michael J. Schweigera, Albert A. Krugerd


Conversion of nuclear waste melter feed to molten glass proceeds in two stages. First, multiple feed reactions evolve copious amounts of gases that are released through open pores. Second, the glass-forming phase traps residual gases, giving rise to a transient foam layer. When the foam collapses and residual refractory grains completely dissolve, the conversion process is virtually completed. In the waste glass melter, the rate of the conversion process (the glass production rate) depends on the feed spreading on the surface of molten glass, the heat needed to convert the feed to melt, and heat transfer rate from the melt pool through the foam layer to the reacting feed layer.

To understand the spreading of the feed slurry, basic rheological parameters of drying feed slurry and dry reacting feed were determined. The conversion heat was measured with simultaneous differential scanning calorimetry-thermal gravimetry. The volume expansion of feed (foaming) was monitored by observing heated feed pellets.

The cold cap (the body of feed floating on molten glass in a continuous waste glass melter in the process of conversion) was produced and monitored in the laboratory-scale melter (LSM). Quenched cold caps were analyzed for spatial distribution of the extent of conversion. Effects of selected feed makeup parameters, such as the glass-forming melt viscosity and particle size of quartz (added as a glass former), were evaluated.

Institutions:

(a) Pacific Northwest National Laboratory, 902 Battelle Blvd.,
Richland, WA 99352, USA

(b) Department of Chemical Engineering, University of Chemistry and Technology Prague, Technicka 5, 166 28 Prague 6, Czech Republic

(c) Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku

(d) U.S. Department of Energy, Office of River Protection,
Richland, WA 99352