JPH0587449B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides at least one
This invention relates to a glass melting tank furnace incorporating several sills. The invention also relates to a process for making glass in which glass forming batch material is melted in a glass melting tank furnace and the melt is allowed to flow over a sill on the bottom plate of the tank while the sill is internally cooled.

In conventional glass manufacturing processes, batch material is passed to one end of a tank where it is melted in a melting zone. The melt moves downstream along the tank and into the refining zone, and the molten glass exits the refining zone of the tank and is processed. In the tank, the melt is at its highest temperature near the center of its heating zone, and therefore its density is lowest. Because of the relatively low density of the melt near this hot spot, an upward flow is formed in the melt, which provides it with a radially directed surface flow to the sides and end walls of the tank. The upflow is provided by an underflow of cooler melt moving along the bottom plate of the tank toward the hot spot. These underflows, on the other hand, are supplied by the melt cooled by contact with the side and end walls of the tank furnace, in particular by the return flow of the melt from the working end of the tank back to the hot spot. This continuous cycle of reheating the molten glass mass in the tank results in very high fuel consumption.

Various attempts have been made to block the bottom flow back to the hot spot by placing sills in the tank to reduce the amount of melt that is periodically reheated, thus reducing fuel consumption. . A further development is that of UK Patent Application No. 1168974, which proposes cooling the sill to slow down the return flow as it traverses the sill. Despite the necessary extraction from the tank furnace by means of cooling, it has been found that the overall thermal economy is improved. Said specification uses a hollow sill with longitudinal internal passages, provided with a lining box serving as a conduit for the liquid coolant, or incorporating a spray conduit for spraying the liquid coolant onto the inner surface of the refractory material forming the sill. is proposed. In the latter case, cooling can be enhanced by blowing air along the internal passages of the sill.

There are many problems encountered in practice but not mentioned in the above specification. For maximum effectiveness in controlling bottom flow, the sill should not be placed too far downstream of the hot spot and should have a significant height relative to the depth of the melt tank. Typically, the height of such a sill is more than half its depth. This means that the top of the sill is exposed to intense radiation from the burners used to supply heat to the furnace. Unfortunately, when a refractory material is exposed to a highly corrosive environment such as molten glass, it erodes rapidly as its temperature increases, and as the temperature gradient across the refractory block becomes steeper, the useful life of the block decreases. It becomes shorter due to internal thermal stress. For this reason, the liquid cooling method described in GB 1168974 is detrimental to the useful life of the sill.

For air cooling, unless the interior of the sill is open at its base, the cooling air must be blown from one side to the other, and at the exit side the cooling air is slightly hotter and the sides of the sill are almost Not cooled.
Also, the heat capacity of air is rather small and it is not possible to pass the air flow through the sill at very high speeds. If it is desired to use a sill whose interior is open at the base, there are great difficulties in its construction.
It will be appreciated that a typical glass melting furnace for the commercial manufacture of glass is on the order of 5 to 12 meters wide. It is by no means easy to construct a sill of this length as one piece. Therefore, when the sill is first made, it is necessary to use a large number of blocks, which must be spaced a sufficient distance apart to take into account the thermal expansion that the blocks undergo when the furnace is brought up to operating temperature. It won't happen. For this reason, and because the sill must be able to resist the forces experienced by the flow in the molten glass bath, a fairly complex sill structure is required.

It is an object of the present invention to provide a glass melting tank furnace incorporating at least one sill with internal cooling means without being too detrimental to the useful life of the sill or requiring a complex sill construction. The objective is to provide a cooling system that is highly efficient without any problems.

According to the invention, there is provided a glass melting tank furnace incorporating at least one sill with internal cooling means, said sill having a hollow cavity extending along the length of the sill and forming at least one internal passage containing a conduit. the conduit being spaced apart from the roof of the passageway and configured to transport liquid coolant along and through the sill, maintaining the flow of liquid coolant through the conduit and maintaining the flow of the liquid coolant through the conduit; A glass melting furnace is provided, characterized in that it includes means for maintaining a flow of gaseous coolant through said passageway above.

The present invention provides a glass melting tank furnace having cooling means that can be operated at high efficiency without substantially reducing the useful life of the sill or requiring a complex sill construction. The most suitable coolants are water and air. In particular, compared to conventional air cooling systems that blow air through the sill at the same velocity, and when the volumetric flow rate of water is sufficient such that the water exits the sill conduit as a liquid rather than as vapor. It has been found that the silver block is better protected by employing the present invention. It also provides better protection than when using conventional water cooling systems. The present invention allows the sill block to be efficiently cooled without subjecting the sill block to severe thermal shock and without causing significant erosion by melt. By employing the present invention, the upper part of the sill, which is the hottest part during use and therefore the greatest problem, is cooled by the gas acting as a heat transfer medium between the refractory material and the liquid coolant flowing through the conduits. The upper part of the sill is cooled at a rate conducive to its long life. The top of the sill is also cooled by radiation directed into the coolant conduits. In practice, it has been found that this radiative cooling typically removes only a small portion of the heat from the sill, but the heat extracted by this radiation is not strong enough to reduce the amount of heat extracted from the sill if the bonds between the blocks of refractory material that make up the sill are not strong. become very important. That is, in such circumstances,
The molten glass that enters the joint is cooled and solidified to seal the joint and prevent the molten material from exiting.

Advantageously, the space between the roof of the passageway and the conduit is located in or penetrates into the upper half of the sill.
This facilitates cooling of the hottest parts of the sill.

Preferably, the conduit is spaced from a side wall of the passageway. Spacing the conduits from the sidewalls of the sill prevents heat transfer losses from these sidewalls to the coolant conduits, limits thermal gradients in these sidewalls, and allows for a long service life.

In a most preferred embodiment of the invention, the spacing between the roof of the passage and the conduit is greater than the spacing between the side wall of the passage and the conduit. This provides a better distribution of heat flux density on the inner surface of the sidewalls and the roof of the sill, resulting in better control of gas flow in the sill and longer service life.

Advantageously, at least one of said conduits carries means for generating a longitudinal compressive force on said sill. This helps the refractory blocks forming the sill to resist the forces exerted on them by flows in the melt.

Preferably, the at least one conduit forms two liquid flow paths separated by a conductive partition, and means are provided for maintaining bidirectional flow of liquid coolant along said flow paths. Employing this feature improves the uniformity of cooling along the length of the sill. It has been found advantageous to construct the conduits forming the two liquid flow paths by welding cheek strips across the flanges of the girders, for example made of I-section or H-section steel.

In a preferred embodiment of the invention, the sill consists of preassembled upper and lower refractory blocks, the upper block having downwardly opening channels providing said passage for gaseous coolant. This is a very simple and convenient way to construct a sill of the desired cross section.

Advantageously, said upper and lower blocks are positioned relative to each other by key members penetrating into said channel. By employing this feature, relative displacements of the blocks caused by flow in the melt are prevented.

Preferably, the conduit is provided within the channel and rests on the key member. This is a very simple way to support the conduit in place. Furthermore, especially if the conduit is large, its weight and the weight of the coolant within it helps stabilize the position of the key member and improves the resistance to displacement of the sill block.

In a preferred embodiment of the invention, a second conduit is arranged within the sill for transporting liquid coolant through the sill at a different level than the level of the first conduit;
Also provided are means for maintaining a flow of liquid coolant through said second conduit. This allows more heat to be extracted from the sill. It will be appreciated that when such a second conduit is provided, it is preferable to provide means for maintaining the flow of said gaseous coolant above the upper of said conduits in order to achieve the full effect of the invention. It will be.

Advantageously, said key element rests on the second conduit, since this simplifies the construction of the sill.

The invention includes a method of making glass in which glass-forming materials are melted in a glass melting tank furnace and the melt is flowed over a sill on the bottom of the tank while the sill is internally cooled. The method is characterized in that the sill is of hollow construction defining at least one internal passageway extending along the length of the sill and containing a conduit, the conduit being spaced apart from the roof of the passageway. for transporting liquid coolant along and through the sill;
A flow of liquid coolant is maintained through the conduit and a flow of gaseous coolant is maintained in the passage above the conduit.

By employing the present invention, the upper part of the sill, which is the hottest part during use and therefore the greatest problem, is cooled by the gas acting as a heat transfer medium between the refractory material and the liquid coolant flowing through the conduits. is,
The top of the sill is thus cooled at a rate that is conducive to its long life. The top of the sill is also cooled by radiation directed into the coolant conduits. Thus, the present invention provides a manufacturing method that allows for efficient cooling of the sill without shortening the useful life of the sill or requiring a complex sill structure.

Preferably, the space between the passageway and the conduit is located within or extends into the upper half of the sill;
Promotes cooling of the hottest part of the sill.

Preferably, the conduit is spaced from a side wall of the passageway. Spacing the conduits from the sidewalls of the sill prevents direct transfer heat loss from these sidewalls to the coolant conduits, limiting thermal gradients in these sidewalls and increasing useful life.

In a most preferred embodiment of the invention, the spacing between the roof of the passage and the conduit is greater than the spacing between the side wall of the passage and the conduit. This results in a better distribution of the heat flux density over the inner surface of the wall and the roof of the sill, resulting in better control of the gas flow therethrough and a longer service life.

Advantageously, longitudinal compressive forces are generated in the sill.
This helps the refractory blocks forming the sill to resist the forces exerted on them by flows in the melt.

Preferably, at least one of said conduits defines two liquid flow paths separated by a conductive partition, and a flow of liquid coolant is maintained in both directions along said flow path.

In a preferred embodiment of the invention, the sill is comprised of upper and lower prefabricated refractory blocks, the upper block having downwardly opening channels providing said passage for the flow of gaseous coolant. This is a very simple and convenient way of constructing a sill whose hottest part forms the wall of the gaseous coolant flow passage, and the hottest part of the sill is cooled in the most favorable manner.

In a preferred embodiment of the invention, a second conduit is arranged within the sill for transporting liquid coolant through the sill at a different level than the level of the first conduit;
Also provided are means for maintaining a flow of liquid coolant through said second conduit. This allows more heat to be extracted from the sill. It will be appreciated that when such a second conduit is provided, it is preferable to provide means for maintaining the flow of said gaseous coolant above the upper of said conduits in order to achieve the full effect of the invention. It will be.

Advantageously, the flow rate of the gaseous coolant is maintained at a level such that the temperature of the gaseous coolant upon exiting the sill passage does not exceed 150°C. This means effective cooling of the sill passages and also avoids the existing air becoming dangerously hot.

Preferably, the flow rate of the gaseous coolant is maintained at a level such that more heat is extracted by the gaseous coolant than by the liquid coolant. Employing this feature has been found to be particularly useful in extracting heat without subjecting the silver block to undue thermal stress.

It is particularly preferred that the flow rate of the gaseous coolant is maintained at at least 30 normal cubic meters per square meter of cross-sectional area of the gaseous coolant passages.

In the most preferred embodiment of the invention, the gaseous coolant is air and preferably the liquid coolant is water. These are the cheapest and most convenient gaseous and liquid refrigerants available.

Preferred embodiments of the invention will now be described in detail with reference to the accompanying drawings.

In Figure 1, the bottom plate 1 of the glass melting tank furnace
is supported by a plurality of I-shaped girders as shown at 2. Except below the sill 3, the bottom plate 1 of the tank furnace comprises a first layer of blocks 4 of insulating material. Below the insulating blocks 4 and sills 3, the girders 2 support a continuous layer of paving blocks 5 of refractory material, while they support a layer of refractory lining blocks 6 and sills 3 interrupting this lining layer. do.

In a typical regeneration furnace with bottom return flow control, the sill 3 is usually located between the last pair of burner holes (counted from the loading end) and the second to last pair of burner holes. However, it can also be placed elsewhere for other purposes.

The sill 3 is constructed using two series of spaced lower refractory blocks 7 mounted on a refractory paving block 5 between refractory lining blocks 6. An optional lower conduit 8, shown in end view in FIG. 1, rests on the paving blocks 5 between the lower sill blocks 7 and supports a series of key blocks 9 projecting from the upper surface of these lower sill blocks. The upper conduit, also indicated by the numeral 8 and shown in cross section, is connected to a series of keyblocks 9.
The sill 3 is placed on a series of upper refractory blocks 1
0, each refractory block is provided with a downwardly opening channel forming an internal passage 11 in the sill 3 which accommodates the protruding part of the key block 9 and the upper conduit 8, and the upper conduit 8 and the roof 1 of the passage.
3 and a space 12 extending along the length of the sill 3
is left behind. The upper and lower conduits 8 may be substantially equal. The upper conduit is shown spaced apart from the side wall of passageway 11, and the lower conduit is similarly spaced from lower sill block 7.

As shown in FIG. 2, upper and lower sill blocks 7, 10 at each end of the sill project beyond the side blocks 14 of the tank furnace on each side for supplying liquid coolant such as water through conduit 8. There is. Also shown in FIG. 2 is an upper conduit 8 passing through the passage 11.
A gas supply line 16 is shown around the blower 15 for supplying a gaseous coolant, usually air.

One end of conduit 8 is shown in plan view in FIG. Conduit 8 is created by welding cheeks 17 between the flanges of I- or H-shaped girders 18 to provide two fluid flow paths 19, 20, with path 1
9, 20 are separated by a conductive partition 21 formed by the web of the spar 18. Each end of the conduit is closed by a welded end plate 22 through which a liquid coolant supply tube 23 for one flow path 19 and a liquid coolant extraction tube 24 for the other flow path 20 are conducted. It will be destroyed. This configuration is Sill 3
to maintain liquid coolant flow in both directions along these flow paths to promote uniformity of cooling along the length of the flow path.

FIG. 3 creates a longitudinal compressive stress in the sill.
It also shows the means. The wing plate 25 has brackets 26 and 27
are welded to each end of the conduit via and support bolts 28 with buffer butts 29 which engage the end faces of the series of upper or lower sill blocks 10,7, as the case may be. By rotating the nut 30 relative to the cradle 31 containing a stack of Belleville washers 32, the desired load can be applied to the ends of the series of sill blocks.

Any deflector baffle, such as that shown at 33 in FIG. 2, or other means, may be provided to safely direct away the heated air coolant. Alternatively, such heated air may be directed to the burner holes as preheated combustion aid, or may preheat fuel and/or air fed to one or more burners by heat exchange or preheat batches fed to the furnace. It can be used by doing.

In a particular practical example, the glass melting tank furnace has a width of 11.1 meters and a design depth (melting depth) of 1.28 meters. The bottom plate of the furnace has a layer of insulating blocks 4, which layer is covered with refractory paving blocks 5.
Supports thicker layers of. These paving blocks are formed from silico-alumina refractory. The backing block 6 is made of high grade refractory material. Sill 3 has a height of 880 mm (above the top of the layer of backing block 6) to allow a melting depth of 400 mm above its top.
will be constructed in The lower sill block 7 is rectangular, with a height of 400 mm and a width (dimensions shown in Figure 1) of 300 mm.
mm, and the length (dimensions shown in Figure 2) is 325 mm. These lower sill blocks are also of high grade refractory and these two series are nominally 200mm apart from each other.
Channels 11 with a width of 200 mm are formed in these upper sill blocks and have semicircular roofs 13 with a thickness of refractory material above them of 300 mm. The key block 9 has a height of 300 mm and a width of 200 mm. The key blocks 9 need not be continuous along the length of the sill, but are preferably arranged to overlap the junctions between successive blocks in each series of upper and lower sill blocks. The keyblock 9 need not be made from the highest grade refractory, but can be made from silico-aluminas refractory. The cross-sectional area of the free space of the passage 11 above and on each side of the conduit 8 is approximately 165 cm ² .

In use, air is pumped into space 12 at 2800Nm ³ /
hour (this means a speed of 30 to 50 m/s and a flow rate of approximately 47 normal cubic meters per square meter of cross-sectional area of the gaseous coolant passages), while water flows only in the upper conduit 8. However, the speed is 120000kcal/hour (approx.
The temperature of the melt near the sill is 1400°C, such that the water leaves at a temperature of 40°C to extract heat from the sill at a rate of 500 MJ/hour).
Of the total heat extracted, approximately 40,000 kcal/hour is extracted by water and 80,000 kcal/hour by air. The air leaves the passage at a temperature of 125°C. In this case, the average temperature of the inner surfaces of the upper sill blocks 10 is calculated to be approximately 320 DEG C., which prevents erosion of these blocks. soda lime glass
When operating the furnace in this manner to produce at a rate of 550 tons/day, the use of a cooled sill results in fuel savings of approximately 6-10%, depending on other operating conditions.

On the other hand, if water is allowed to flow only along the upper conduit 8 without blowing air along the space at such a speed that the water outlet temperature is 40°C, the temperature will be about 85,000 or
It is calculated that 90,000 kcal/hour will be extracted and the average temperature of the inner surface of the upper sill block 10 will be approximately 600°C. If the upper conduit 8 is removed and the sill is cooled exclusively by blowing air into the passage 11,
Although it is possible to extract somewhat less than 80,000 kcal/hour, this means that the average temperature inside the sill is over 600°C. At 800° C., the molten glass is freely flowing and may even penetrate into the joint space where it will be severely eroded, thereby inviting further penetration of the molten glass.

[Brief explanation of the drawing]

Figure 1 is a partially cross-sectional detailed side view showing a part of the glass melting tank furnace including the sill, and Figure 2 is an elevational view of the sill with the upper structure of the tank omitted, in the direction of the arrow in Figure 1. Cross-sectional view of a tank furnace, seen in
FIG. 3 is a plan view of one end of a conduit conveying liquid coolant along and through the sill, showing the means for creating a longitudinal compressive force on the sill; 1...Bottom plate, 2...Girder, 3...Sill, 4...Insulating block, 5...Paving block, 6...Lining block, 8...Lower conduit, 9...Key block, 10...Upper block , 11...inner passage,
12...Space, 13...Roof, 15...Blower,
16... Gas supply pipe, 28... Bolt, 30...
Natsuto, 31...Cradle, 32...Watsushiya, 33...Batsuful.

Claims (1)

[Claims] 1. Incorporating at least one sill, the sill having a hollow structure defining at least one internal passageway extending along its length, and having internal cooling means within the passageway. In a glass melting tank furnace, the internal passageway includes a conduit, the conduit being spaced apart from the roof of the passageway and for transporting liquid coolant along and through the sill, the liquid coolant passing through the conduit. and means for maintaining a flow of gaseous coolant through said passageway above said conduit. 2. A glass melting furnace according to claim 1, wherein the space between the roof of the passageway and the conduit extends into or into the upper half of the sill. 3. A glass melting tank furnace according to claim 1 or 2, wherein the conduit is spaced apart from a side wall of the passageway. 4. The glass melting tank furnace of claim 3, wherein the space between the roof of the passage and the conduit is larger than the space between the side wall of the passage and the conduit. 5. A glass melting tank furnace as claimed in each of the preceding claims, wherein at least one of said conduits carries means for creating a longitudinal compressive force on said sill. 6. Each of the preceding claims, wherein at least one of said conduits defines two flow paths separated by a conductive partition and is provided with means for maintaining bidirectional flow of liquid coolant along said flow paths. Glass melting tank furnace described. 7. A glass melting tank furnace as claimed in each of the preceding claims, wherein the sill is constructed from upper and lower prefabricated refractory blocks, the upper block having downwardly opening channels providing said passages for the flow of gaseous coolant. 8. A glass melting tank furnace as claimed in claim 7, wherein said upper and lower blocks are arranged relative to each other by key members penetrating into said channel. 9. A glass melting tank furnace as claimed in claim 8, wherein said conduit is located within said channel and above said key member. 10 disposing a second conduit within the sill for transporting liquid coolant through the sill at a level different from the level of the first conduit, further comprising means for maintaining a flow of liquid coolant through said second conduit; A glass melting tank furnace as set forth in each of the preceding claims. 11. The glass melting tank furnace of claim 10 further comprising means for maintaining the flow of said gaseous coolant through the upper one of said passageways. 12. Claim 8 or 9 and Claim 1, wherein the key member is located on the second conduit.
Glass melting tank furnace according to item 0 or item 11. 13 A sill provided on the bottom plate of the tank,
melting the glass forming batch material in a glass melting tank furnace, the sill being a hollow structure defining at least one internal passageway extending along its length, while flowing the melt over the sill;
A method of manufacturing glass for cooling the interior of the sill, wherein the internal passageway includes a conduit spaced apart from the roof of the passageway for transporting a liquid coolant along and through the sill. A method characterized in that a flow of liquid coolant is maintained through the conduit and a flow of gaseous coolant is maintained above the conduit and through the passageway. 14. The method of claim 13, wherein the space between the roof of the passageway and the conduit extends into or into the upper half of the sill. 15. The method of claim 13 or 14, wherein the conduit is spaced from a sidewall of the passageway. 16. The method of claim 15, wherein the space between the roof of the passageway and the conduit is greater than the space between the sidewall of the passageway and the conduit. 17. A method according to any one of claims 13 to 16, wherein a longitudinal compressive force is generated in the sill. 18. Each of claims 13-17, wherein at least one said conduit forms two flow paths separated by a conductive partition, and wherein a flow of liquid coolant is maintained in both along said flow paths. Method described. 19. A method according to claims 13-18, wherein the sill is comprised of upper and lower prefabricated refractory blocks, the upper block having downwardly opening channels providing said passageway for the flow of gaseous coolant. 20. A second conduit is disposed within the sill for transporting liquid coolant through the sill at a level different from that of the first conduit, and further comprising maintaining a flow of liquid coolant through said second conduit. Range 1
The method described in each item 3 to 19. 21. The method of claim 20, wherein the flow of said gaseous coolant is maintained through an upper one of said passageways. 22 Claims 13 to 21 maintain the flow rate of the gaseous coolant at a level such that the temperature of the gaseous coolant as it exits the sill passage is below 150°C.
Methods described in each section. 23. Claims 13-22 each of which maintains the flow rate of the gaseous coolant at a level such that the amount of heat extracted by the gaseous coolant is greater than the amount of heat extracted by the liquid coolant. Method. 24. A method as claimed in any one of claims 13 to 23, wherein the flow rate of the gaseous coolant is maintained at a rate of at least 30 normal cubic meters per second per square meter of cross-sectional area of the gaseous coolant passages. 25. The method according to each of claims 13 to 24, wherein the gaseous coolant is air. 26 Claim 1 in which the liquid coolant is water
The method described in each item 3 to 25.