JPH01133943A - Method and apparatus for liquefying heat-meltable material - Google Patents

Abstract

PURPOSE: To liquefy a hot meltable material with a small energy, by supplying a powdery hot meltable batch material into the cavity of a vessel lined with refractory on the inside, thermally melting the exposed part and allowing the molten material to flow out.

CONSTITUTION: The aperture of a bottomed cylindrical vessel 10 lined with refractory 35 supported by tabs 36 on the wall on the inner side and liners 21 of the powder batch material inclined to a parabolic surface shape is covered with a dome-shaped cap 11 in an upward direction. Next, the powdery hot meltable batch material is supplied into the cavity of the vessel 10 via a water cooling chute 20 and the batch material on the surfaces of the liners 21 are thermally melted by the flames from plural burners 22 extending through the cap 11. The liquefied batch material 27 is passed downward on the liners 21 and is dropped from a drain outlet 25 provided with a refractory ceramic bushing 26 onto a receiver 28.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention U.S. Pat. No. 4,381,934 discloses a method for liquefying materials such as glass batch materials or similar materials, which A liner of powdered material, such as , acts as an insulator to protect the side walls of the volume from the intense temperatures within the container. In a preferred embodiment, the liner surrounds the central cavity of the container, and the liner prevents liquefied material from freely flowing out of the container, and is maintained by supplying relatively cold material onto the liner. The advantage of such equipment is that it allows for the liquefaction of batch materials without the need for extensive contact of the product stream with contaminating refractory materials, and without the need for extensive heat treatment due to forced cooling of the walls of the container. The point is that high temperatures can be generated without any loss.

For melting layers on refractory walls, see US Pat.
No. 31.619: No. 1.889.511: No. 2.00
No. 6.947; and No. 2.593.197. These devices place a relatively small volume of process material in contact with a relatively large area of refractory material, and therefore have a substantial potential for contamination of the process material by corrosion of the refractory material. It has the disadvantage of being

A prior art example of a water-cooled melting vessel is U.S. Pat.
, No. 834.157 (Bows), No. 3°917.479
No. 4,061.487 (Kiyonaga). Each of these employs water cooling as the primary means of protecting nearly all sidewall sections of the vessel, resulting in large temperature gradients between the cooling fluid and the molten material within the vessel. This results in a large amount of energy being wasted through the walls of the container.

The liquefaction method in the aforementioned U.S. Pat. Although the batch material liner may occasionally collapse randomly, the system is generally self-healing by supplying additional batch material to the container.

However, a steady-state collapse within the liquefaction container sometimes results in a reduction in the thickness of the liner, especially in the upper part of the container, and that part of the container side wall is exposed to temperatures, which If continued for a sufficient period of time, this may lead to deformation or other thermal degradation of the container.

Instabilities in the wall thickness of the batch material can occur, for example, during start-up or when changing the batch feed rate or heating rate. Also, during normal operation, the batch liner collapses more rapidly at its mid-height, resulting in undercutting of the liner and, ultimately, sudden collapse of the liner from the upper region. Such an abnormal condition may not be a major problem if it is of short duration, but if it persists or occurs frequently, it is advisable to provide thermal protection against it. Easy thermal deformation is particularly problematic in that it creates dynamic instability when the container is rotated with respect to the preferred embodiment of the liquefaction process.

US Pat. No. 3,689,679@ (Niwa et al.) discloses a slightly different type of silica melting process in which portions of the container are cooled. As shown in this patent,
Cooling takes place on most of the sidewalls in the area of actual melting. This patent does not cover melting at the surface of the liner as the present invention does.

SUMMARY OF THE INVENTION In the present invention, a batch material of glass or the like is liquefied on the surface of a cavity in a container, and the primary thermal protection is provided by a powdered material compatible with the material to be liquefied, preferably the batch material itself. This is done by an insulating liner. The top of the container is provided with a refractory liner to protect the container sidewalls from excessive thermal degradation in the event that the liner thickness is reduced excessively during irregular operations. Contact between the refractory material and the liquefied material is limited because the area of the refractory material that becomes exposed is relatively small and because in most cases the refractory material is exposed only intermittently. becomes impractical. The refractory liner serves to thermally stabilize the container when the powder liner is reduced beyond a minimum thickness, and the contact is only occasionally and in areas where the powder liner is completely missing. only occurs. Operating parameters are adjusted to restore the powdered liner to cover the refractory liner, thus minimizing exposure of the refractory liner.

Selectively and additionally ensuring the thermal stability of the volume during irregular operation is obtained by cooling the upper part of the container in the area of the refractory liner. Due to the insulating effect of the refractory liner, very little heat is extracted from the liquefaction process by the cold Ill. When the powder is healthy, the energy lost by cold W is very small. Furthermore, cooling has a significant effect on heat transfer only intermittently and in limited areas. Pre-cooling lJ'l preferably consists of spraying water onto the outside of the container.

DETAILED DESCRIPTION Referring to the particular embodiment shown in FIG. , has a top that is entirely open and a bottom that is open except for the drain outlet. The drum 10 is mounted for rotation about a vertical axis in a manner described in detail below. Within the liquefaction vessel a generally encased cavity is formed by a lid structure, generally indicated at 11, said lid being provided with a stationary support. The lid 11 is preferably made of a refractory ceramic material and may take a variety of shapes as known to the refractory furnace construction industry. The preferred device shown in the figures is a spring arch structure made of a plurality of refractory blocks 12 domed upwardly.

In the exemplary arch structure shown, the arch block rests on one side of the peripheral support structure proboscis 13. A plate block 14 extends slightly below the upper edge of the drum 10 and is supported by a static support plate 15. A seal block 16 may be provided to close the gap between the arch block 12 and the plate block 14. As for this lid, it should be understood that the plate-shaped flat hanging case 1 may be adopted.

The batch material, preferably in powder form, is fed into the cavity of the heating vessel by a water cooling chute 2o. A batch material holder 21 is held on the inner wall of the drum 10 and acts as an insulating lighter. As the drum is rotated, the feed chute 20 directs the batch material to the top of the liner 21. The heating operation for liquefying the batch material is carried out by six or more burners 22 extending through the lid 11. Preferably, a plurality of burners 22 are arranged around the periphery of the lid, directing their flames over a wide area of the liner 21. The burner is preferably water cooled to protect it from the harsh environment within the vessel. Exhaust gas exits the container through an opening 23 in the lid 11. As the batch material on the surface of the liner 21 liquefies, it flows downwardly over the sloping liner to a central drain opening 25 at the bottom of the vessel. Said frontage 2
5 may be provided with a refractory ceramic bushing 26. The stream of liquefied material 27 free falls from the vessel into a static receiver 328 where it undergoes additional processing to complete the melting process. The liquefied material is allowed to flow freely from the surface of the drum 21 so that it
When it passes through, it is in an incompletely molten state. The liquefied glass batch material at that point typically contains large amounts of gaseous reaction products and may also contain some unmelted particles.

At the border between the upper edge of the rotating drum 10 and the stationary lid 11 an atmosphere seal is provided, which forms a static, circular, water-containing trough and an air flow from the rotating drum into said trough. It consists of a circular flange member 31 extending downward. A similar static water trough 32 and flange 33 extend downwardly from the rotating drum at the lower end of the drum.

One embodiment of a protective refractory liner according to the present invention is shown in FIG. 1, with a refractory liner 35 provided around the inner upper circumference of the drum 10. The extent of liner 35 is generally only needed on a small area of the drum, with powder layer 21 acting as the primary protective liner over most of the drum surface. In the aforementioned regions, the contact between the refractory liner 35 and the liquefied material is irregular, resulting in the powder liner 2
It only occurs intermittently, such as when the top of No. 1 collapses. By adjusting the feed rate and/or burn rate, the powder liner can be restored to provide sufficient coverage of the refractory liner '35 in the normal mode of operation.

Because the powder liner 21 is parabolically sloped, the -E section of the liner is thinner and therefore it is the small upper area of the container that is more exposed and would benefit from a refractory liner. Become. The lower part of the powder liner is thicker and more stable, and it remains insulated under the powder liner 21 without the disadvantage of extending the refractory liner to most of the sides of the drum. It will be maintained in a state with little or no functionality.

However, if desired for structural convenience, the refractory liner may be provided throughout the drum.

The refractory liner 35 is, for example, a ring or tab 3
It is shown supported on 6. Preferably, the refractory liner is made of a RNable cement that can be poured into place and cured with the aid of a suitable mold.

Metal anchors (not shown) fused inside the drum 1o may be used to secure the cast refractory liner to the drum. A preferred arrangement for installing the refractory liner is shown in FIG.
An enlarged portion 37 is provided in the drum 10 to create a step supporting the drum 10. Also preferred in this embodiment is a refractory cement cast around the anchor. The thickness of the refractory liner 35 or 38 is sufficient to thermally insulate the metal drum from the effects of heat inside the drum and to prevent deformation of the drum during periods of irregular operation. The required insulation value will depend on the particular temperature and construction. For example, in the described embodiment, J of 5α
Tsuza's silica cement has been found to be sufficient.

As shown in FIG. 1, the refractory liner may be combined with external forced cooling to excessively preserve the geometrical stability of the drum 10. Cooling may be applied to approximately the same area as the refractory liner is provided, even if the refractory liner no longer provides sufficient insulation.
It serves to prevent the metal drum from overheating. drum 1
Various devices can be employed to cool the upper part of 0 to a high degree of IIJ. The coolant may be a liquid (eg, water) or a gas (eg, air). In the illustrated example, the water is directed against the outside of the top of the drum. The water flow is supplied by piping 40;
The spray shield 41 restricts the spray to a space close to the drum. Use stream water is collected in a circular trough 42 and discharged by piping 43 that extends downwardly along the side of the drum 10 and rotates therewith. The drain water from piping 43 drains conveniently into the water trough 32 of the bottom atmosphere seal.

As with refractory liners, external cooling devices need to be applied only to limited areas of the sidewall where the internal liner is most prone to collapse. In most cases there will be a small, upper part of the drum corresponding to less than half the height of the drum. The internal liner 21 normally acts as the primary thermal protection for most areas of the drum sidewall, and the refractory liner acts as the secondary protection. Applying external cooling to the portion of the drum protected by a refractory liner extracts very little thermal energy from the heating process taking place inside the drum, and if a powder liner is present, It becomes much less. Therefore, the cooling area may be larger than necessary with little or no loss in thermal efficiency. A layer of powdered glass batch material of at least 2 as has been found to be an effective insulator, and even thinner layers result in very little heat transfer through the batch layer. Cooling may be used only when needed, but since there is a small amount of heat transfer, there is some benefit to keeping the coolant flow continuous and keeping the outside of the vessel away from the coolant. By maintaining the temperature, thermal shock can be prevented when cooling is restarted.

The basis for rotatably supporting and driving the drum 10 is a support table 50, which, as shown in FIG. 1, has the shape of a hollow shaft with an overall rectangular cross section. The support ring 50 surrounds the drum and is spaced apart from the drum. The link device for connecting the support ring 50 to the drum 10 in this embodiment consists of a plurality of support rods 51. The number of rods 51 and the size ζ are inversely related and depend on the season of the particular drum at full load.

In theory, three rods could support the drum, but four or more rods (preferably eight or more) could be used in a bicycle spoke-type arrangement; Thereby, no relative rotation occurs between the drum 10 and the ring 5o. In such an arrangement, the rods are not located in the radial plane of the drum, but extend along a vertical plane that does not intersect the vertical axis of the drum, and the planes of adjacent rods lie within the vertical plane of the drum. It passes on both sides of the axis. As the container grows, the number of rods increases to distribute its load,
In embodiments of the type shown, as many as 24 rods are possible. The rod is a preferred link-shaped device as it presents little obstruction to the sides of the drum, thus allowing access during assembly and maintenance and free air circulation. and can also prevent the accumulation of any spilled material.

The rods 51 are held in place by nuts 52 with bulbous ends at their ends, which are further received in recessed sockets in upper and lower support blocks 53 and 54, respectively. There is.

In one aspect of the invention, the upper support block 53 includes:
It is mounted on the support ring 50 at a position above the m-center C of the container under load. The lower support block 54 has an outer ring 5 attached to the drum 10 at a height significantly lower than the height of the upper support block 53.
5 or similar. The portion of the support rod 51 whose height at which its end engages the support ring 50 exceeds the height of the small center C is preferably maximized to optimize the self-centering effect. However, one could achieve some of the self-centering advantages of the present invention by providing any degree of flarity between them. From a practical point of view, in most cases the height of the upper engagement level will be subject to an 11 limit.

Structural supports for the stationary lid 11, latches and other attachments to the lid, and the lid-to-drum interface extend the supporting elements of the rotating drum above the maximum height of the drum. will interfere with any attempt to make it exist. As shown, the liner material 21 is tapered to be thicker at the bottom of the cylindrical drum, so the center of gravity will normally be located in the lower half of the drum height. Therefore, in other words, the height of the support can also be expressed as being located at the upper half of the height of the drum.

The linkage, such as rod 51, is preferably attached to the drum in an area of the drum that is relatively cool and therefore not subject to significant thermal strain. The increased thickness of the liner 21 as it approaches the bottom of the cylindrical drum makes the lower portion of the drum a more desirable mounting location. Although it is sometimes possible to attach it to the upper half of the drum, it is preferable to attach it to the lower half. i b In a preferred arrangement, the attachment takes place at or above the height of the center of gravity C of the container when loaded with the normal amount of material including the liner.

Instead of having a generally cylindrical shape as shown, the container 10 may have a downwardly converging frustoconical shape or as shown in U.S. Pat. No. 4,469,387 (Heithoku et al.) Other shapes such as a stepped shape may also be used. In such a case, the center of gravity will not be in the lower half of the container, but the preferred height of the support will be above the center of gravity and the height of the attachment to the container will be in the lower half.

An inclined track 60 that makes rotational contact with a plurality of inclined wheels 61 is provided on the lower side of the support ring 5o. The wheels 61 are rotatably supported by bearings 62 fixed to a suitable stationary structural member such as a beam 63. The wheels 61 support the vertical load of the drum and its contents, and the number of wheels is selected depending on the distribution of the load, but for a typical industrial type as shown, It is considered that 8 pieces is appropriate. Orbit 6
The contact surface of 0 is inclined downwardly towards the drum 10 and thus has a part-conical shape.

The lateral restraining force applied to the rotating drum 10 and the support ring 5o is provided by a plurality of wheels 70 that are pressed against the outer periphery of the support ring 50. The lateral restraining ring 70 is rotatably supported on a rigid support device 71, which is radially adjustable with respect to the drum 10. At least three lateral restraint wheels 70 are provided, preferably four, and said wheels 70 are preferably pneumatic tires. At least one wheel 70 is driven by a motor (not shown), thereby supporting the support table 50 and thus the drum 10.
and rotate. Rather than acting as an absolute restraint on the rotating elements, the wheels 70 serve to dampen any vibration or reciprocating movement of the drum axis from its predetermined position. Wheels 70 damp any horizontal movement of the drum and support ring; in use, the conical boundary between track 60 and vertical support wheels 61 provides the main centripetal force. Similarly, the damping effect of the vibrational movement of the drum axis by the support above the center of gravity will also be assisted by the damping effect of the wheels 70.

Obviously, other changes and modifications as known in the art are possible without departing from the scope of the invention as defined by the appended claims.

The invention has been described in connection with the liquefaction of glass batch materials, for which the invention is particularly useful.

This includes flat glass, glassy materials, glass containers, sodium silicate, and all types of specialty glasses. The invention can also be used to liquefy other materials such as metal ores or other glassy or ceramic materials that are not strictly glass. Additionally, although the preferred practice, especially when processing flat glass, involves employing nearly chemically identical compositions of the processing batch material and the powdered liner of the liquefaction vessel, there may be slight differences between them. The difference is
In certain cases, no contamination occurs and can therefore be considered satisfactory.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a preferred embodiment of a rotating liquefaction vessel having an upper refractory liner with selective cooling in accordance with the present invention; FIG. It is an enlarged sectional view of the upper part. In the figure, J3 shows the following: 10 Container 20 Powder material supply device 21 Powder p-liner 25 Outlet 35 Refractory liner.

Claims (10)

[Claims] (1) A method for liquefying a hot-melt material, comprising: feeding a powdered batch material into a cavity surrounded by a liner of powder material on an interior side wall of a container; and liquefying the exposed portion of the powder material. Primarily, heat is applied to the cavity to allow the liquefied material to flow out of the container, and the thickness of the powdered liner is maintained sufficiently to cover most of the sidewalls of the container. By insulating from the heat inside the tea, that part of the container is protected from excessive thermal deterioration and if the powdered liner is not thick enough to adequately insulate the container. , in a small part of the side wall of the container, said small part of the container,
protection by retaining a refractory liner over the interior of the container, maintaining the thickness of said liner;
A method for liquefying hot-melt materials, characterized in that it is carried out by supplying additional powdered material and allowing the liquefied material to flow out of a liner. 2. The method of claim 1, wherein protecting the small portion includes directing a coolant into contact with an outer surface of the sidewall portion. (3) A method according to claim 1, in which the small portion protected by the refractory liner is present at the upper end of the container. (4) A method according to claim 1, wherein the thickness of the powdered liner in the small portions increases sequentially. 5. The method of claim 2, wherein cooling the sidewall portion includes directing a flow of coolant fluid toward an outer surface of the sidewall. (6) A method according to claim 1, wherein the material being liquefied is made of a glass batch material, and the liner is also made of a glass batch material. 7. The method of claim 1, wherein the container is rotated about a substantially vertical axis, powdered material is dispensed at the top of the container, and liquefied material is discharged at the bottom of the container. , a method of liquefaction of hot-fusible materials in which the liner is sloped towards a relatively thin section at the top of the container. (8) In an apparatus for liquefying a heat-fusible material, the container has a side wall and a bottom portion that are attached to rotate around a substantially vertical axis, the container being for supplying powdered material into the container. of a thermofusible material, the container having an outlet for allowing the liquefied material to flow out of the container, and a refractory partial liner on the side wall portion of the container. Liquefaction equipment. (9) The apparatus according to claim 8, wherein the cooling device comprises a device for spraying a liquid coolant onto the outer surface of the side wall. 10. The apparatus of claim 8, wherein the refractory liner relates only to the upper portion of the vessel side wall.