Bubbles in Glass Melting Process

I am not of the glass industry, but I would suggest that you graduate the heating process further so that the glass does not melt too fast, as it seems to be doing: Seems as if air is getting trapped because of quick melting of the glass without enough-time for the melting glass to expel all air first before becoming fully molten.

I hope that this helps

Cylinder glass was one such improvement. The molten glass was blown into a cylinder which was cut apart, then reheated and flattened. In the 16th and 17th Centuries, the English discovered that using coal instead of wood in their furnaces produced a much clearer glass. Although the panes were wavy and full of bubbles, and sometimes light amethyst or amber in color, people could actually see through their windows.
The solution to that problem was: sodium sulfate, sodium chloride, or antimony oxide

the sequence in which you add the ingredients might allow you to have a low viscosity stage where bubbles rise to the surface. Melted glass can be very viscous and this makes the bubbles rise very slowly. Of course, you can wait for a lomg time = slower production

dig in these areas.

http://www.google.ca/search?hl=en&q=viscosity+%2Bglass+%2Bfurnace&btnG=Google+Search&meta=

Ok, then I have another idea. When manufacturing glassfiber for example we can use the power of centrifugal energy.

Fiberglass Reinforced Plastic (FRP) centrifugal pressure blower for exhaust or process handling of corrosive air streams for low volume 3000 CFM and for up to 24" SP.

In theory, if we rotate the entire structure 360 degrees in circular motion, like in a moving discotec(also my idea). but I believe we could get rid of these evil little bottles with either use vibrations or centrifugal power, or we play a good song as low as possible, the base would take care of them, Technotrance or Drum Base..maybe.

I have not fooled with industrial level glass furnaces but I have a small electric art glass furnace (55lb. crucible) I recently built for my hot glass shop. When I melt the cullet (96 COE) I use and I will at first get a ton of "seed" bubbles. I found that if I raise the temp 100 degrees (2200 F) Over the normal working temp. for a couple of hours and then drop it back to working temp. (2100 F) as quickly as I can it will squeeze the bubbles out. I am not sure this is an option with your set up but it really takes most of the bubbles out of my glass.

Dear pipewelder,

Thank you very much of your information.Yes you are right,i have tried the method before but it is good for few days then back again.

We have very precious and highly complicated MicroProcessor PLC from Siemens and the whole glass end port regenerative furnace was from well known glass industry system designer from German.

We fired by Natural gas and assisted by electric booster system. with total of 180Ton/day.

Thank you and Regards

The glass bubble formation causes because of following reasons

1. Raw materials source change

2. Age of furnace with time its actual operation al temperature is lower than what you are reading out of thermocouple

3. Refractory is corroded and started faster dissolution in the glass melt.

Without knowing which one dominates your problem it will be hard to resolve issue in this forum. If you need you can send a detail email on Masyood@gmail.com and I may be able to guide you through

Hi,

I am not a glass expert but some questions may help:

The bubbles may be air - entrapped in powdery raw material,

may be carbon-dioxide by decomposition of soda,

or may be water brought in absorbed to the raw materials, may be chemically bound.

And there may be a gas production from sulfur in bad lime reacting with oxygen or hydrogen.

If entrapped air or CO2: try slower and more distributed input by sieves that act very well distributed. This will result in a thin fresh molten layer on-top of a more massive molten bath of glass. Outlet should be at the bottom. Because of the thin fresh layer with some overheating from above will lower the viscosity substantially and the small distance to the surface will facilitate a rapid escape of bubbles.

If water in the raw material (inevitably you have some): try to preheat or calcine your raw material or premixed material carefully. You will never be able to remove water completely (naked surfaces need 450°C for 1 hour in high-vacuum to get rid of absorbed water), but any preheating on trays with a minimum thickness of material to let the vapor come off freely will help a lot.

If sulfur: try to get a chemical analysis of your lime and lower the acceptable sulfur content.

Have success and please report the unsuccessful trials and the successful solutions.

RHABE

There is not a lot of information to go on with the question. I am new to this division of my company, just having spent several years working with quartz.

I have forwarded your question to a member of our team at a facility in France. Perhaps he will be able to offer some quick references to check.

What refractories are you using today? supplied by? How long since your last repair/rebuild? We have offices globally and would like to help.

Regards,

SRS

Dear SGO,

Thank you for your assistance,At the melter side wall (glass contact) we are using product from SEPR,We just furnace rebuild and in operation since Nov 08. Pls email to aikhh@yahoo.com for further detail of your company.

Thank you

Dear SGO

Melting quartz and melting soda lime silicate glass are two different world. Quartz is high viscosity non to slow reactive melt against soda-lime silicate glass which is reactive melt. I have worked and did my MS and Ph.D. in this field and last thirty years working in the field of glass and adhesive.

I have no idea of the problem but what ever the input is appears to be be connected with batch materials or over used refractories or low melt temperature.

I wish I had more information to remove two and said clear path for corrective action. If he provides details then it will be easy to help the guy out by sharing personnel experience in the glass related problem he has. I have made few thousand tons of soda - lime silicate glass and always thought I have seen most of the problem and still I beleive this but I may be fooling myself since the guy had issue and I am not able to say any thing concrete other than providing three options to him.

This is because of lack of information or shallow knowledge base after 30 years in the field of glass and glass ceramic I have

dear aikhh

we have also 38 sq m furnace as same as you have. we have same seviere problem if you got good solution plz help

although , we played with temp ,graduated higher or lower temp but still no use at only 80 tpd

Hi Guest,

Thank you to drop in an email to discuss of this issue,by the way we are produce the bottle for food industrial, our furnace already 14yrs old and operate with natural gas + electrical booster at 550kw. thus our output is 100 tpd, we are used 30% of cullet ratio . Melter temp at 1580 deg C. of course to reduce the pull out is one the best solution.

After reduce pull out and notice that seed,blister in the product are significant reduce. then we slowly increase the pull out again.

Pls email to me aikhh@yahoo.com if u need some more discussion of this issue or any thing in glass container industrial

Best Regards