Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
  • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
  • C03B5/235—Heating the glass
  • C03B5/2353—Heating the glass by combustion with pure oxygen or oxygen-enriched air, e.g. using oxy-fuel burners or oxygen lances
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
  • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
  • C03B5/18—Stirring devices; Homogenisation
  • C03B5/183—Stirring devices; Homogenisation using thermal means, e.g. for creating convection currents
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
  • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

• the present invention relates to a method for manufac ⁇ turing glass in a melting furnace, in which glass batch material is charged to the furnace at one end thereof and forms a blanket layer on molten bath material present in the furnace and is heated by said molten material and by the flame of at least one furnace burner, such as to melt during its passage to the other end of the furnace and mix with said molten bath mater ⁇ ial, and in which molten glass is taken-out at said other end of the furnace.
• the invention also relates to a melting furnace for use when manufacturing glass in accordance with this method.
• the through-flow rate to correspond to the melting energy that can be utilized and the admix ⁇ ture that can be achieved.
• the amount of energy which can be supplied to the furnace is limited, inter alia. by the fact that the resultant furnace temperature must not be excessively high. Normally, it is the furnace arch or furnace vault temperature at the hottest point in the furnace which is determinative in this respect. Mixing efficiency is dependent on temperature gradients in the molten bath, since admixture of the glass melt is totally dependent on the flows that can be achieved in the bath.
• Convective flows are highly significant to admixture and homogenization of the glass mass in con- ventional melters, although other factors, such as the introduction of batch material into the furnace and the removal of molten glass therefrom also influence the movements occurring in the glass mass.
• Hot glass which rises to the surface in the hottest zone of the melt will thus flow towards the colder input end in and beneath the surface layer of the molten bath and the batch material floating thereon which is dissolved successively in the melt.
• the density of the glass becomes higher, therewith result ⁇ ing in a downward flow which then returns to the hot- test zone, along the bottom of the furnace.
• Another flow in the upper layer of the melt is directed from the hottest zone towards the removal end of the furnace, which is colder and where the flow is directed downwards. That part of the melt which is not be removed from the furnace returns to the hottest zone, along the furnace bottom.
• the position of the hottest zone is controlled with this type of furnace by means of the furnace burners.
• the European Patent Specification 0 127 513 describes a glass melting method in which the glass batch material is heated intensively at the infeed end of the furnace with the aid of an oxygen-fuel-burner. This enables a large amount of booster energy to be supplied to the furnace, without placing limitations on the furnace arch.
• a main object of the present invention is to provide a glass manufacturing method which will enable additional thermal energy to be supplied so as to increased pro ⁇ duction yield without detriment to the quality of the molten glass taken from the furnace.
• the present invention is based on the realization that considerable additional thermal energy, or booster energy, can be supplied to the glass batch material at the infeed end of the furnace, inter alia, with the intention of accelerating melting of the glass batch material, provided that additional thermal energy is also supplied to the melt at its hottest point at the same time, thereby maintaining in the melt the tem- perature gradients required to achieve the desired convection currents therein.
• Another object of the invention is to provide a melting furnace for the manufacture of glass which operates in accordance with the method.
• a method according to the invention and of the kind defined in the introductory paragraph of the descrip ⁇ tion is particularly characterized by combining addi ⁇ tional, intensive heating of the batch material at the infeed end of the furnace with the aid of at least one so-called oxygen-fuel-burner, with additional, inten ⁇ sive heating of the molten material in the furnace substantially in the hottest zone with the aid of at least one further so-called oxygen-fuel-burner.
• This method thus enables heating of the glass batch material and the molten glass mass to be intensified, so as to increase production yield while maintaining quality as a result of maintaining in the melt the convection currents necessary for mixing and homo ⁇ genizing the glass mass.
• Figure 1 is a longitudinal-sectional " View of an inventive melting furnace.
• Figure 2 is a cross-sectional view of the furnace illustrated in Figure 1.
• Figure 3 is a view of the furnace of Figure 1 from above and partly in section and illustrates the burner positions.
• Figure 4 is a view corresponding to Figure 3 with respect to a furnace equipped with end-mounted furnace burners.
• the melter illustrated in Figures 1-3 is of the kind equipped with side-mounted furnace burners.
• the furnace includes a rear end-wall 1 and a front end- and parti ⁇ tion wall 2, a bottom 3, an arched roof 4 and two side- walls 5.
• the glass batch material 6, from which the glass is manufactured and which may possibly contain crushed glass, and desired minerals, is charged through an infeed opening 7 in the rear end-wall 1.
• the batch material charged to the furnace will therewith float on the relatively highly-viscous bath 8 of molten glass present in the furnace.
• the batch material 6 will melt and mix with the molten glass. All of the batch material will have melted into the underlying molten glass, when reaching the hottest zone of the bath 8, this zone being referenced 9.
• the side-mounted burners comprise fuel-supply nozzles
• regenerators 15 arranged along the sides of the furnace, these regenerators being shown schematically in Figures 2 and 3.
• the burners on one side-wall of the furnace are used alternately with the burners on the other side-wall, the hot combustion gases passing out through the openings 11 in the side-wall whose burners are at that moment inactive.
• the combustion gases function to heat the regenerators, the heat of which is subsequently used to pre-heat the combustion air when the burners on this side-wall of the furnace are activated.
• the burners are controlled so that the hottest zone 9 in the glass bath 8 will be located at the position desired, normally at a distance from the inlet end 1 corresponding to 2/3rds to 3/4ths of the length of the furnace. It is endeavoured therewith to produce flows in the molten bath caused by temperature gradients in said mass, along the paths illustrated by the arrows A and B respectively. Molten glass, which in both paths returns to the hottest zone 9 along the bottom 3 of the furnace, rises towards the surface of the bath at said point and is divided into two flows which are directed towards the colder regions at the rear end-wall and the front end-wall of the furnace respectively, where the glass sinks to the bottom and then returns to the hot ⁇ test zone. No account has been taken of lateral flows, among other things, in this somewhat simplified ex ⁇ planation. The flows discussed above, however, repre- sent the main flows desired in the majority of melters.
• the region extending from the infeed opening 7 to the hottest zone 9 represents a melting zone in which glass batch material 6 charged to the furnace is melted down in the molten glass 8.
• the region extending between the hottest zone 9 and the front end-wall 2 of the furnace forms a fining zone, in which final homogenization of the glass 8 takes place and gas bubbles are permitted to leave the glass bath.
• the final, homogenized glass is removed through an outfeed opening 12 and supplied to subsequent glass-manufacturing machines.
• the infeed end of the furnace at least one, and in the illustrated embodiment two, highly- effective booster burners 13 of the oxygen-fuel-type.
• the flames of these burners are directed onto the still solid batch material, so as to accelerate heating of said material.
• the burners are fed with a mixture of fuel and oxygen, so that the flame temperatures will be very high, and consequently non-combustible consti- tuent ⁇ of atmospheric air need not be heated in the burners. This results in more effective combustion.
• the booster burners 13 are combined with at least one further burner, in the illustrated embodiment two mutually opposing burners 14 of the so- called oxygen-fuel-type mounted on the side-walls 5 of the furnace.
• the flames of these burners are preferably directed obliquely down onto the surface of the bath at the position corresponding to the hottest zone 9 in said bath.
• the temperature in the hottest zone is increased with the aid of these burners, therewith enabling the temperature profile of the furnace and the temperature gradients in the bath to be optimized essentially in a manner commensurate with that in a furnace which is not provided with booster burners.
• the booster burners 14 are directed slightly downwards onto the bath sur ⁇ face, suitable angles of inclination may be 0-30 * , preferably 10-20 * .
• the burners may also be directed slightly obliquely to the inlet end of the furnace.
• the booster burners 13 mounted at the infeed end of the furnace are directed obliquely forwards and inwards in relation to the feed direction of the batch material 6.
• the precise positioning and alignment of both the burners 13 and the burners 14 may, however, be determined in dependence on the type of furnace used and on prevailing operating conditions.
• the number of burners may also be varied as desired, although the hub of the invention is that additional thermal energy, or booster energy, is supplied to the furnace at both the infeed-end thereof and in essen ⁇ tially the hottest zone of the furnace.
• the described oxygen-fuel-type burners used to boost thermal energy may also be used to replace one or more conventional furnace burners. When the furnace is in operation, all booster burners can be activated simultaneously or, alternatively, only those booster burners which are located on the same side as those typical furnace burners which are active at that time.
• the oxygen-fuel-burners used may have any desired configuration and may, for instance, comprise burners of the kind sold by AGA AB under the designation "Oxy- fuel-burners".
• a suitable power range is from 0.1-4 MW per burner.
• the combustible gas used is preferably natural gas, although other gases may, of course, also be used.
• Figure 4 is a schematic illustration of the invention as applied in a melter of the kind in which the conven ⁇ tional furnace flame 16 has a horseshoe configuration and departs from a burner 17 and 18 respectively on one side of the rear end-wall 21 of the furnace, the waste gases being sucked out through an opening 19 and 20 provided in the opposite side of said end-wall.
• the air openings 19, 20 also communicate with a respective regenerator 22 and 23, and consequently the combustion air can be pre-heated by alternating between the two burners ⁇ such as to reverse the flow of air through said openings.
• the numeral 24 identifies an inlet opening through which batch material is charged to the furnace, and the ultimate glass mass is removed through the outfeed opening 25.
• additional, intensive heating of the batch material is achieved with the aid of a highly-intensive burner 26 of the so-called oxygen-fuel-type located between the air open- ings 19, 20.
• the furnace is provided, in accordance with the invention, with two additional booster burners 27, 28 of the so-called oxygen-fuel- type, the flames of which additionally heat the molten glass in the hottest zone of the furnace, in a manner similar to that described with reference to the earlier embodiment.
• booster burners 27, 28 it is possible, also in this case, to either activate one or both of the mutually opposing booster burners 27, 28.
• the single burner 26 on the rear end-wall 21 of the furnace can be supplemented with an additional booster burner optionally located for achieving desired heating of batch material charged to the furnace.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Combustion & Propulsion (AREA)
• Glass Melting And Manufacturing (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20375698

Family Applications (1)

Country Status (7)

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• 1989
  • 1989-04-17 SE SE8901382A patent/SE463512B/sv not_active IP Right Cessation
• 1990
  • 1990-04-02 BR BR909007298A patent/BR9007298A/pt not_active Application Discontinuation
  • 1990-04-02 WO PCT/SE1990/000214 patent/WO1990012760A1/en not_active Application Discontinuation
  • 1990-04-02 CA CA002050933A patent/CA2050933A1/en not_active Abandoned
  • 1990-04-02 JP JP2506715A patent/JPH04504708A/ja active Pending
  • 1990-04-02 EP EP90908094A patent/EP0469093A1/de not_active Withdrawn
• 1991
  • 1991-10-16 FI FI914885A patent/FI914885A0/fi not_active Application Discontinuation

Non-Patent Citations (1)

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