Forehearth for conditioning glass

Details Forehearth for conditioning glass Forehearth for conditioning glass

1983-06-16

1985-01-22

Lindsay, Robert

Glass manufacturing

Gathering or drawing pool type furnace

Supplemental heating or heat exchange means associated with...

65346, 65347, 65356, C03B 523

Patent

active

044949740

DESCRIPTION:

BRIEF SUMMARY
This invention relates to forehearths for use in glass production.
In glass production, molten glass is produced in a melting furnace and then passes along a forehearth before being led away for further processing. For example in the production of glass articles the molten glass from the forehearth may pass to a spout where it is formed into gobs which are subsequently formed into the desired articles. Generally in any particular installation there are several forehearths each with a spout fed by a single melting furnace.
Conventional forehearths comprise a refractory trough along which the molten glass flows and which is provided with an insulating roof and heaters (e.g. gas burners) are arranged along the side of the trough within the forehearth. In addition cooling air may be blown into the forehearth transversely or longitudinally of the direction of glass flow.
The roofs of such forehearth are generally made up of individually ground fire-bricks to provide air passages therethrough, the fire-bricks being overlain with insulating bricks. Thus the forehearths are very time consuming to construct and tend to require substantial steelwork as superstructure.
The viscosity of molten glass is highly temperature dependant. Molten glass usually leaves any particular melting furnace at a fixed temperature. However the desired temperature of the glass as it leaves the forehearth for further processing varies for example depending on the type of glass being used, e.g. whether it is white or coloured glass, and the required working viscosity. In addition in order to achieve uniformity in the eventual product glass, the viscosity of the molten glass from the forehearth should be homogeneous throughout.
The temperature, and thus also the viscosity, of the molten glass is controlled as the molten glass flows along the forehearth. Temperature control within conventional forehearths has been achieved by means of heat exchange radiation between the molten glass and the cooled roof surface and heat losses through the forehearth structure and heat supplied to the installation from the heaters. In fact in order to obtain acceptable temperature control in this way quite substantial quantities of heat input are required and thus, in these days of increasing energy costs, running costs are undesirably high.
It is known that as the molten glass moves down the forehearth there tends to be a greater temperature loss at the sides of the molten glass stream than in the centre and also that the glass next to the trough walls tends to move more slowly than that in the centre of the stream. This of course leads to inhomogeneity across the glass stream with the glass next to the side walls being of greatest viscosity. The provision of heaters in the conventional forehearths of course compensates to some extent for this heat loss. However, in addition to being costly, this is not entirely satisfactory as regards the amount of control of the installation which it allows.
All previous forehearths have been of uniform construction along their entire length, the length itself depending upon the amount of cooling required and also of course on the amount of space available.
According to the present invention there is provided a forehearth for use in glass production which forehearth comprises a refractory trough for molten glass with an insulating roof thereover, and means for heating glass in the trough and means for blowing cooling air across the inside roof surface; the forehearth being constructed of at least two sections which have different insulating characteristics from each other. In the two forehearth sections either the trough or the roof (or both) of the different sections may have the different insulating characteristics.
By choosing sections having the appropriate insulating characteristics, the forehearth according to the present invention can be constructed such as to provide optimum working conditions for any particular installation alongs its entire length. These optimum working conditions will vary from installation to in

REFERENCES:
patent: 1893060 (1933-01-01), Peiler
patent: 2089690 (1937-08-01), Cornelius
patent: 2144973 (1939-01-01), Honiss
patent: 2649903 (1953-08-01), Russell
patent: 3198619 (1965-08-01), Nuzum
patent: 3201219 (1965-08-01), Frazier et al.
patent: 3248203 (1966-04-01), Cunningham
patent: 3582310 (1971-06-01), Avery et al.
patent: 3645712 (1972-02-01), Ihrig et al.
patent: 3676099 (1972-07-01), Fultz
patent: 3999972 (1976-12-01), Brax

Affiliated with

Also associated with

Rating

Forehearth for conditioning glass does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Forehearth for conditioning glass, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Forehearth for conditioning glass will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-565112