Types of Stirrer Systems at the Forehearth Equalizing Zone for Glass Quality Improvement

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Questions and Answers

What is the main purpose of using paddle stirrers in the forehearth equalizing zone?

Enhance UV resistance of the glass

Minimize thermal shock in the glass chemistry

Eliminate surface cords in the glass container (correct)

Reduce the appearance of light streaks

When are hybrid stirrers typically utilized in the equalizing zone?

To help with glass temperature homogeneity in darker glass colors

To minimize light streaks due to reduced glasses oxidation (correct)

To eliminate surface cords ('cat-scratch') in the container

To enhance gob thermal homogeneity

What is the primary function of helix stirrers in the forehearth equalizing zone?

Reduce light streaks caused by oxidation

Minimize thermal shock in the glass chemistry

Help with UV resistance of the glass

Enhance gob thermal homogeneity (correct)

Which type of stirrer is specifically used to minimize the appearance of light streaks?

Hybrid Stirrers Signup and view all the answers

In which type of glass operation would helix stirrers be particularly beneficial?

Antique Green glass production Signup and view all the answers

What does the Appendix section provide reference for regarding the stirrers used in the equalizing zone?

Description of different stirrer types Signup and view all the answers

Why is it important to evaluate the external temperature of the metallic casing in the glass production process?

To prevent glass penetration into the insulation layers Signup and view all the answers

What is a key factor to determine the wear of the refractory channel blocks in the glass production process?

The average emissivity of the metallic casings Signup and view all the answers

How are the casing temperatures in the glass production process evaluated?

By thermal scanning with an infrared camera Signup and view all the answers

What can glass penetration into the insulation layers of metallic casings lead to in the glass production process?

Surface cords ('cat-scratch') issues Signup and view all the answers

Why does glass flow prefer to travel along shorter flow paths in the glass production process?

Due to greater velocity and higher temperature Signup and view all the answers

How can the rotation direction of the tube be used to optimize homogenization in the spout according to the text?

By aligning it against the direction of higher speed and/or temperature Signup and view all the answers

What role does monitoring the external temperature of metallic casings play in glass production processes?

To prevent glass quality issues Signup and view all the answers

Study Notes

Stirrer Systems in the Forehearth Equalizing Zone

Three types of stirrer systems are used to help with glass quality issues and improve glass conditioning: Paddle Stirrers, Hybrid Stirrers, and Helix Stirrers.

Paddle Stirrers

Used to eliminate surface cords (“cat-scratch”) in the container and minimize the appearance of color streaks caused by over-reducing conditions in the glass chemistry.
Can help improve gob thermal homogeneity.

Hybrid Stirrers

Used to minimize the appearance of light streaks caused by the oxidation of reduced glasses and color streaks caused by over-reducing conditions in the glass chemistry.
Can help improve gob thermal homogeneity.

Helix Stirrers

Used to help with glass temperature homogeneity in forehearths that operate at high pull or darker glass colors (e.g., UV and Antique Green).

Metallic Casing Temperatures

External temperature of the metallic casing in the refiner, alcove, forehearth, and spouts is a key factor in determining wear of refractory channel blocks and glass penetration into insulation layers.
Temperature ranges affect glass quality, leading to blisters, devitrification, and surface cords (“cat-scratch”).
Temperatures should be evaluated by thermal scanning with an infrared camera using an average emissivity of 0.65 for metallic casings.

Safe Operational Ranges

The following are safe operational ranges for metallic casing temperatures.

Glass Flow and Homogenization

Glass flow prefers to travel along shorter flow paths with higher velocity and temperature.
Setting the rotation direction of the tube against the direction of the glass flow with higher speed and/or temperature helps optimize homogenization in the spout.

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Description

Learn about the three different types of stirrer systems - Paddle Stirrers, Hybrid Stirrers, and Bubbling Stirrers - used at the forehearth equalizing zone to address glass quality issues and enhance glass conditioning. Each type serves a specific purpose in improving the overall quality of glass production.