CN1678539A - Convective method of heating glass sheets using compressed air in conjunction with heated oven air - Google Patents

Abstract

This invention discloses a semi-convection pressure air system for heating glass plates, comprising: a heating chamber located within a furnace; a longitudinal conveying mechanism extending through the heating chamber; a compressed air source; a plurality of compressed air ducts extending longitudinally within the heating chamber, each duct being fluidly connected to the compressed air source, each duct being oriented along a length direction parallel to the longitudinal conveying mechanism, and each duct being equipped with a series of spaced-apart nozzles; a distribution pipe fluidly connected to the air source and the ducts; each nozzle having an upper port for receiving hot furnace gas, a sidewall hole for receiving compressed air, a mixing chamber for mixing the compressed air and the furnace gas to form a hot mixed air, and a lower port for discharging the mixed air onto the glass plate in the furnace chamber.

Description

Convective method of heating glass sheets with compressed air combined with hot furnace air

technical field

The present invention relates to semi-convective pressure/forced air systems and methods for heating glass sheets for subsequent processing. More specifically, the systems and methods of the present invention are used to heat low-E coated glass sheets (low "e" glass) prior to tempering and then temper the glass sheets. The present invention includes a new and improved nozzle for delivering a hot mixture of compressed air and hot furnace air to a glass sheet in a furnace.

technical background

Prior U.S. Patent No. 5,591,734, issued September 14, 1999 to TGL Tempering Systems, Inc. of Cinnaminson, NJ, which discloses a method for tempering low "e" Semi-convective forced air system for tempering coated glass sheets in which the furnace air manifold is placed along the direction of flow/travel of the glass sheets. The holes in these manifolds that allow compressed air to be blown onto the glass sheet to facilitate heat treatment are small. The temperature of the air impinging on the glass (panel) is about 426°C. The glass plate must be heated to 634°C before tempering the glass plate. Therefore once the temperature of the glass plate reaches 426°C, the convection system must be switched off. If the air is kept blowing for too long, the panes will come out too cold and crack. The glass sheet needs to be irradiated by infrared rays to obtain a final processing temperature of about 634°C. This is the slowest form of heat transfer for low "e" glass sheets and adds extra time to the heating cycle.

Contents of the invention

The object of the present invention is to replace the small holes in the manifold of US Patent 5,951,734 with a new and improved lance which draws hot air from the furnace and mixes it with compressed air to form hot mixed air, The hot mixed air is then blown onto the glass plate. For every cubic foot of compressed air introduced into the nozzle, two cubic feet of furnace gas should be sucked into the nozzle. This allows the convection system to be used throughout the cycle, reducing cycle time, especially for soft-coated low "e" glass. In addition, the greater volume of air passing through the furnace creates stronger convection, which increases the rate of convective heat transfer and contributes to both faster cycle times and improved glass sheet quality.

Description of drawings

Figure 1 is a side view of a duct of a compressed air assembly with a nozzle inserted therein and a hanger adapted to suspend the duct from the furnace roof.

FIG. 2 is a bottom view of FIG. 1 .

Fig. 3 is a front view of the compressed air feed pipe in Fig. 1 .

FIG. 4 is an enlarged detail view of the area marked 4 in FIG. 3 .

Figure 5 is an enlarged side view of a portion of the conduit and nozzle shown in Figure 1 .

Figure 5a is an end view of Figure 5 viewed from the left of Figure 5 .

Figure 5b is a top view of one of the nozzles of Figure 5 .

FIG. 6 is a bottom view of FIG. 5 .

FIG. 7 is a rear view of one of the nozzles of FIG. 5. FIG.

FIG. 8 is a front view of the nozzle of FIG. 7 .

Figure 9 is a side view of the rollers, ducts, lances, clamps, hangers and compressed air feed ducts within the furnace.

Figure 10 is a top view of the furnace conduits and nozzles.

Figure 11 shows the arrangement of an aspiration system comprising an air tank, compressed air feed pipe, distribution pipe and spray pipe.

Figure 12a shows a side view of a conduit flange.

Figure 12b shows a front view of one face of the flange in Figure 12a viewed from the left of Figure 12a.

Figure 12c shows a front view of the other face of the flange seen from the right side of Figure 12a.

Detailed ways

Referring now to the drawings, FIG. 7 shows a spout 21 in rear view and FIG. 8 shows the spout 21 in front view. Compressed air enters the lance 21 through holes 23, furnace gas is drawn into the lance through upper ports 25, and the compressed air and furnace gas mix in a mixing chamber 26 in the lower part of the lance 21 to form a hot air mixture. This air mixture of compressed air and furnace gas is discharged through the lower port 27 onto the glass sheet S, thereby heating the glass sheet for further processing, such as tempering.

For ease of processing, the hole 23 has been optimized as a 30° inclined hole, but other angles can also be made. The diameter of the holes is 0.080mm, so particles formed inside the compressed air delivery system can be blown through these holes. The diameter of the holes can be varied as necessary or desired.

The upper port 25 is flared at the inner bell mouth 29 so that furnace gas can be sucked into the nozzle 21 more easily.

The lower port 27 flares inwardly at a flare 30 on the outer surface of the nozzle 21 .

The side view of FIG. 5 and the bottom view of FIG. 6 show the air boost nozzle 21 being pressurized through a manifold or conduit 31 which delivers compressed air to the nozzle 21 . FIG. 5 b shows the orientation of the holes 23 in the nozzle 21 relative to the manifold 31 . The holes 23 face the opposite wall (of the manifold) so that particles are not blown directly into the holes 23 and block them.

Figure 5 shows a side view of the manifold 31 with the lances 21 passing therethrough under pressure.

FIG. 6 shows a bottom view of the manifold 31 with nozzles 21 in FIG. 5 .

The number of nozzles 21 per manifold 31 may vary depending on the length of the manifold 31 . Typically, the center-to-center spacing of the nozzles 21 is 30 cm.

Figures 1 and 2 show a compressed air system assembly in which compressed air is injected through a compressed air feed pipe 33 into the center of conduit 35 between sub-conduits 35a and 35b.

A hanger 37 suspended from the furnace roof supports the conduits 35a and 35b.

The compressed air assembly includes two three-quarter inch conduits 35a and 35b with pressurized nozzles 21 passing therethrough, a central tee 33 for supplying compressed air, and connecting the ends of the tee 33 The cross member 33a is connected to the flanges 39 of the conduits 35a and 35b. This flange 39 is used so that the conduits 35a and 35b can still be separated after they are heated and to allow the conduits 35a and 35b to be cleaned about once a year.

The conduits 35a, 35b are made of special stainless steel 310 that produces only a small scale in the tempering temperature range of the glass furnace.

Figures 12a, 12b, 12c show details of the flange 39 used to connect the conduits 35a, 35b to the cross member 33a of the compressed air tee 33.

Tee 33 brings compressed air to conduits 35a, 35b and into nozzle 21 .

The hanger 37 supports the conduits 35a, 35b from the furnace roof.

Figures 9, 10 and 11 show the arrangement of the suction system for this super "e" suction system. It is to be noted that, as in prior patent No. 5,951,734, the conduits 35a, 35b are arranged in the direction of travel of the glass sheet and perpendicular to the rollers 41 in the furnace 43.

The compressed air enters the furnace 43 through a compressed air feed distribution conduit 33 and conduits 35a, 35b. When the compressed air passes through the furnace 43 and reaches the nozzle 21, it is about 426°C, and is then mixed with the hotter furnace gas of about 676°C to 704°C. The mixing forms mixed air, which is delivered to the glass sheet S through the nozzle 21 at about 690°C.

The glass sheet S is swung back and forth in the furnace 43 until the temperature required for tempering is reached.

The semi-convective compressed air system for heating the glass sheet S comprises: a heating chamber 43a located in the furnace 43; a longitudinal conveying mechanism 43b extending through the heating chamber 43a; a compressed air source 43; Extended compressed air conduits 35, each fluidly connected to a source of compressed air and each oriented parallel to the length of the longitudinal delivery mechanism 43b, are mounted on the conduits 35 with a series of A nozzle 21; a fluid connection between the air source 45 and the distribution conduit 35 between the conduit 35; each nozzle 21 has an upper port 25 to receive hot furnace gas, for receiving the side wall hole 23 of compressed air, with A mixing chamber 21a between the hole 23 and the lower port 27 for mixing compressed air with furnace gas to form hot mixed air, and a lower port for discharging the mixed air onto the glass plate S in the furnace chamber 43a 27.

Claims (8)

1. A nozzle for delivering a mixture of compressed air and hot furnace gas to a glass plate in a furnace, comprising: a tube having a centerline and sidewalls, said tube has an inner top forming an air inlet for receiving hot furnace gas from the furnace, a hole in the side wall of the tube forming a side wall inlet for receiving compressed air, a mixing chamber located in the tube below the compressed air inlet for mixing the compressed air and the furnace gas in the tube to form the furnace gas and the compressed air at a temperature higher than that of the compressed air air mixed with air, An exhaust port at the bottom of the tube through which the mixed air is blown onto the glass plate. 2. The nozzle according to claim 1, characterized in that, The holes are at a 30° angle to the centerline so that the mixing action creates an attractive force to draw furnace gas into the top port, The discharge port flares inwardly on the outer surface of the tube. 3. The nozzle of claim 1, wherein: An apparatus comprising the lance and a delivery conduit for delivering compressed air to the lance was used to heat the glass sheet to about 634°C to prepare the glass sheet for tempering. 4. A semi-convective pressure-air method for heating glass sheets using a mixture of compressed air and hot furnace gas, comprising: passing a series of glass sheets through a furnace containing hot furnace gas, heating the air in the furnace by radiation, Compressed air is passed through the nozzles in the furnace, The hot furnace gas is sucked into the nozzle, mixing the compressed air with the hot furnace gas in the nozzle to form a hot air mixture, blowing the hot air mixture from the lance onto the glass sheet passing through the furnace to bring the glass sheet to a temperature suitable for tempering, and The glass plate is tempered. 5. The method according to claim 4, characterized in that the method comprises: For every cubic foot of compressed air passed to the lance, two cubic feet of furnace gas are drawn in. 6. The method according to claim 4, characterized in that the method comprises: Heat the furnace gas to about 676°C, Compressed air at about 38°C is passed into the furnace in a delivery pipe, and the compressed air is heated by the furnace gas so that it is heated to about 426°C when it reaches the nozzle, And deliver the mixed air at about 634°C to the glass plate. 7. A compressed air assembly for delivering compressed air to a nozzle in a furnace, comprising: two conduits each having a series of spaced nozzles under pressure therethrough, the two conduits are aligned with each other and the inner ends of the conduits are spaced apart, a central tee that delivers compressed air to the conduit, said central tee has a main member and a cross member, flanges at both ends of the cross-member, and the flange on the inner end of the duct connected to the flange on the cross member, As a result, after the conduit has been heated, they can still be separated by removing the flange, so that the conduit can be cleaned. 8. A semi-convective forced air system for heating glass sheets comprising: a heating chamber located within the furnace, a longitudinal transport mechanism extending through the heating chamber, a source of compressed air, a plurality of compressed air conduits extending longitudinally within the heating chamber, Each of said conduits is fluidly connected to the source of compressed air, Each of the conduits is oriented parallel to the length of the longitudinal conveyor, the conduits carrying a series of spaced nozzles, a distribution tube fluidly connected to the air source and the conduit, Each of the lances has an upper port for receiving hot furnace gas, a side wall hole for receiving compressed air, a mixing chamber for mixing the compressed air and the furnace gas to form hot mixed air, and a A lower port on the glass plate for discharging the mixed air into the oven chamber.

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