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ICG Tutorial: “Clear As Glass”

Clear As Glass: Tutorial on Thermodynamics & Chemical Technology in Glass Melting

Wednesday, June 3, 2009

8 AM – 12 PM

The tutorial addresses Master level or 1. year Ph.D. students with a focus on glass science and technology. Students may have acquired a background in materials science of glass, and may have gained an overview over glass fabrication processes. But often, they feel a lack of instruction in the theoretical background and the general concepts of industrial high-T processes. The tutorial aims at closing this gap. It is true, the tutorial cannot replace an entire course. But it will convey the meaning of the important buzz words, and help to gain some practice in applying the related concepts. The following four lectures – comprising calculation exercises -are offered:

1. Session (Reinhard Conradt)

1.1. Thermochemistry of mineral raw materials, glass melts, and solid glass. (40 min)
Calculation of enthalpies and entropies of real raw materials, and industrial glasses and glass melts. Use of tabulated thermodynamic data. Calculation of the latent heat of the batch-to-melt conversion, and the tangible heat stored in a melt. An extended text plus power point sheets is provided.

1.2. The glass furnace – a thermochemical reactor. (40 min)
Heat balance, power balance, entropy generation. Fundamental concept of heat exchangers. Radiation exchange between flames, refractory surfaces, and semi-transparent melt. Types of reactors: Residence time distribution, transfer functions, active and dead volume, concept of critical path. An extended text plus power point sheets is provided.

2. Session (Ruud G.C. Beerkens)

2.1. Thermochemistry of combustion (40 min)
Different types of available fuels. Short summary on reaction mechanism of combustion in glass furnaces. Combustion calculations: gros and net calorific values of real fuels, oxygen/air demand, flue gas volume and composition, adiabatic flame temperature. A short discussion on cause of NOx & dust emissions, evaporation, carry-over will be presented. Heat transfer from flames to melt. An extended text plus power point sheets is provided.

2.2. Mechanisms, thermochemistry and kinetics of refining. (40 min)
Physics and chemistry of refining and fining. Mechanism of primary and secondary fining. . Examples of the traditional sulfate fining process for soda lime silicate glasses. Technological measures supporting the fining process. Sulfate chemistry in relation to gas evolution from glass melts. An abstract plus power point sheets is provided.

3. Session (Pavel Hrma)

3.1 Transport phenomena during glass melting. (60 min)
Kinetics of heterogeneous reactions comprising particulate and dispersed matter. The role of diffusion, heat transfer, and surface tension. Molten salts, glass-forming melt, dissolution of solids, evolution of gases and foam generation. Interaction of molten glass with refractory walls and with furnace atmosphere. Bubble removal.

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