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| Posted By: Michael Greenman from Glass Manufacturing Industry | ||
| July 29, 2004 | 12:50 PM | Refining Glass |
| Several research projects underway within the DOE/GMIC glass portfolio provide an opportunity for the introduction of new refining technologies to increase melting efficiencies and lower costs. The GMIC has hosted several workshops on this topic over the last two years, and is beginning to study four possible choices: 1) sonic, 2) centrifugal, 3) vacuum (or low pressure) and 4) Helium gas. If you have thoughts on which of these is most likely to permit practical applications to be developed, or would like to be involved in the ongoing study, please comment in this "string". | ||
| Replied By: Ray S. Richards | ||
| 23 - Mar - 2005 | 5:48 PM | vacuum refining |
| This is my first attempt to enter a chat room. I did not see any other entries. How do I access them? There have been at least two commercial uses of vacuum refining that I have heard of. I have never seen it but as I understand it, PPG's P10 process fed newly created melt into a vacuum chamber of large dimensions. It foamed and they had to use an oxy-fuel flame to break the foam. The melt depth was large, 8 to 11 ft deep (??) to get back to atmospheric pressure. I presume this is where the long holding time homogenized the glass by diffusion. They used it for a number of years for special glass products. I wonder how they would modify it if they were to repeat the endevor? I would think that convection currents down the walls of the vacuum melt zone would result in a minimum residence time much less than the average holding time for that unit. Did they ever measure the residence time distribution with tracers? This would be a fun discussion to have with their project engineers. Bet the lawyers won't let it happen. | ||
| Replied By: Michael Greenman from Glass Manufacturing Industry | ||
| 13 - Apr - 2006 | 8:28 AM | Refining |
| Thanks to Ray for your input! Yours was the first response! This sort of "forum takes a while to "catch on"! We will update our industry listserv on increased activity and encourage greater involvement and contributions to the "string"! Perhaps some of the P10 engineers might have something to add? | ||
| Replied By: Charles Merivale from Amalgamet Canada | ||
| 17 - Apr - 2006 | 12:39 PM | Glass Refining |
| At equivalent temperatures, small quantities of lithium reduce glass viscosity, the same mechanism which enables fuel savings from lithium. Stokes Law tells us reduced viscosity will accelerate fining, perhaps also removing some other less benign fining agents. Many lithium users have noted this but I am not aware of any specific studies which recorded any hard data, the usual focus being energy consumption and production rates. If anyone has any experience specifically in this area with a willingness to share their findings, it might help others. This is a different approach from those mentioned in the headlines; it can be done now, no matter what your furnace or plant configuration, with no need for any capital investments. | ||
| Replied By: Dan Nolet from Corning Incorporated | ||
| 11 - Jan - 2008 | 8:49 AM | Vacuum fining |
| Lots of patent history in this topic. As Ray noted above, PPG had a production version for a while, though my understanding is that they have abandoned this technology and it may be possible to get a public disclosure of their history now that the dust has settled. Someone from GMIC should contact them to see if this is possible. The other industrial application is Asahi Glass reduced pressure fining for LCD applications. There are many Asahi patents in the US and European files and they generally cover the technology as applied. Asahi continues to use this to my knowledge and with the competition in LCD would not be likely to discuss publicly. Same things with helium and sonic applications. Lots of patent history is out there but neither of these has had commercial applications that I know of. The study comes back up about every 10 years or so. | ||
| Replied By: Ray S. Richards from Associated Technical Consulta | ||
| 11 - Jan - 2008 | 3:47 PM | Vacuum refining |
| Thanks to Dan Nolet for his helpful coments. I checked the Asahi patents and note the problems of foaming etc. My vacuum concepts are different. In my approach, foaming would not be a problem and homogeniety shoud be outstanding. As you are probably aware, the Richards sermon is melt at lower temperatures using high shear with the glass in the foamy state, then refine it. I wish I could find someone to team up with on testing my concepts. | ||
| Replied By: Randall Schmidt from Kuttner LLC | ||
| 11 - Jul - 2008 | 9:34 AM | vacuum refining |
| PPG abandoned the P10 process in 1998. They are about out of the glass business all together now. Their lawyers probably would still come after me if I say too much. I worked on it for 8 years. The vacuum refining worked but had control and materials issues. Foaming was an issue, but controllable. The melting process ahead of it had bigger issues. Some of the observations here are correct, some less so. I know some of the things that I would have done differently, but I am just an electrical engineer. | ||
| Replied By: C. Philip Ross from Glass Industry Consulting | ||
| 14 - Jul - 2008 | 11:28 AM | PPG P10 |
| The Technical and Economic Assessment (TEA) document sponsored by DOE reviewed a number of melting & refing technologies considered in the past (including PPG's P10). I would be interested in speaking directly with anyone with observations or opinions on the issues raised in the report (downloadable at www.gmic.org). Please email me at gici@cox.net to set up a way of communicating directly. Thanks | ||
| Replied By: Elliott Levine from DOE | ||
| 14 - Jul - 2008 | 3:46 PM | |
| I am appreciative of those who have continued to post threads here that are of interest to the glass community. I do not mean to serve as the moderator for this forum, but I would like to encourage members that to the extent possible - to please keep their posts on-line rather than take the comments off-line. by so doing, more participants from the glass community can benefit. | ||