US2773611A - Method of and apparatus for feeding vitrifiable materials into glass furnaces - Google Patents

Description

Dec. 11, 1956 G. L. HENRY ET AL METHOD OF AND APPARATUS FOR FEEDING VITRIFIABLE MATERIALS INTO GLASS FURNACES Filed Aug 4. 1949 I ll-76.2

' INVENTOR GEORGES LEO/V HENRY, EDGARD BRIO/MRO ATTORNEY United States Patent METHOD OF AND APPARATUS FOR FEEDING xglgllllglABLE MATERIALS INTO GLASS FUR- Georges Leon Henry and Edgard Brichard, Jumet, Belgium, assignors to Union des Verreries Mecaniques Belges S. A., Charleroi, Belgium, a Belgian company Application August 4, 1949, Serial No. 108,555 Claims priority, application Belgium August 23, 1948 6 Claims. (Cl. 214--35) The present invention relates to methods and apparatus for feeding vitrifiable materials into glass tank furnaces, by introducing the said materials, which have previously been mixed to form a homogeneous mass known as a batch, into the furnace in the form of a substantially continuous sheet or layer of regular thickness, which floats on the molten bath and melts in proportion as it progresses into the furnace.

It has been found that it is sometimes advantageous not to mix all the vitrifiable materials prior to their introduction into the furnace. For example, it may be advantageous if the glass scrap (or cullet) is not mixed with the other materials as is generally the case, and, instead, on the one hand an intimate mixture of all the other materials, and on the other hand the cullet in pieces of suitable dimensions are fed into the furnace in two distinct superposed layers.

It is also possible, with a view to obtaining heterogeneous glass having a decorative character, to add fusible materials of different coloration or texture from the basic glass is such a manner that they do not mix completely with the basic glass during the melting.

The object of the present invention is to provide an improved method and means for feeding such susbtances intov the furnace in two or more continuous superposed sheets. For this purpose, in addition to the materials directly subjected in the known manner to the impulse imparted to them by a mechanical device by which they are carried forward in the form of a sheet, materials are introduced into the furnace by depositing them on the surface of the molten glass bath at one or more points at which the glass participates in the movement of the sheet. These materials are distributed by means of additional hoppers which can be situated in front, on the sides and/ or to the rear of the mechanical driving device.

In order that this statement may be readily understood, reference will be made to the accompanying drawings,

which show by way of example two forms of embodiment of the invention.

Fig. 1 is a vertical section taken through the'longitudinal axial plane II (Fig. 2) of a tank furnace, on the head of which there is mounted a feeding arrangement of the type described in our copending application Serial No. 706,006, filed October 26, 1946, now Patent No. 2,711,837 of which this application is a continuation-in-part.

Fig. 2 is a plan view corresponding to Fig. 1,

Fig. 3 is a vertical section similar to Fig. 1, taken along the line IIIIII of Fig. 4, showing a furnace equipped with arrangements according to the present invention.

Fig 4 is a plan view corresponding to Fig. 3, and

Fig. 5 is a vertical section showing another application of the invention in conjunction with a furnace-feeding arrangernent other than that shown in Figs. 1 to 4.

In Figs. 1 and 2, 1 is the tank of the tank furnace, the said tank being extended rearwardly by a head 2 of equal .or smaller width, through which the materials are introduced into thefurnace. The tank 1 and the head 2 con- 2,773,61 1 Ce Patented Dec. 11, 1 956 tain molten glass 3. 8 is the bladed roller of the feeding arangement forming the subject of our copending application Serial No. 706,006, filed October 26, 1946, now Patent No. 2,711,837 of which this aplication is a continuation-in-part. The materials coming from a hopper 6 are deposited on the molten glass 3 in the head 2 and spread in the form of a continuous sheet 4 of substantially uniform thickness. The rotation of the roller 8 feeds the sheet forwards towards the inside of the furnace.

The present invention involves utilization in a novel manner of the phenomenon described below and which was disclosed and applied in a useful manner in the more general method of feeding materials to glass melting furnaces which is claimed in our aforementioned copending U. S. Patent No. 2,711,837:

It is known that thermal currents are set up in the mass of molten glass 3 due to the temperature differences obtaining between dilferent points of the furnace. In the forebay 2 these thermal currents have the general direction illustrated by the arrows a (Figs. 1 and 2). In fact, the glass on the surface cools and tends to sink to the bottom of the head owing to the increase in density resulting from the cooling. It is replaced by hotter glass coming from the inside of the furnace. This spontaneous current therefore opposes th'eprogress of the sheet. Thus, if the rotational movement of the roller 8 is stopped, the sheet of batch 4 returns to the rear under the action of the current a.

Now, it has been observed that the flow of materials 4 created by the feeding arrangement communicates its impulse to the glass mechanically by adherence, thus destroying the action of the thermal currents a on'the surface and setting up at the glass surface in forebay 2 a surface current, the direction of which is represented by the arrows b in Figs. 1 and 2. This current b manifests itself not only on the glass lying below the sheet 4, but also to the rear and on the sides of the said sheet. The surface glass situated in the neighborhood of the sheet of batch is therefore carried along by the said sheet and advances therewith. There therefore exists on the sides of the sheet 4 and to the rear of the point at which this sheet is deposited on the molten glass 3, a zone in which the exposed surface glass participates in the forward movement of the sheet of batch.

As soon as the furnace-feeding arrangement has been set in motion, the currents a disappear, and currents b are obtained, which are permanently established as long as the feeding arrangement is in motion. It is thus sutiicient to deliver one part only of the vitrifiable materials to the feeding arrangement, since the current b to which the progress of these materials give rise enables the other materials to be introduced at any other point at which it appears desirable.

One method of carrying the invention into effect therefore consists in introducing the materials through one or more additional hoppers or other equivalent devices. Figs. 3 and 4 illustrate by way of example the case where the materials are fed into the furnace from a number of different and separate lots.

The case which will arise in practice may be more or less complicated, but it will always involve an application of the principles hereinbefore set forth.

It will be assumed that a feeding arrangement 8 is in operation on the forebay 2 and forms a sheet or layer 4, which it feeds towards the tank 1 (Figs. 3 and 4). In Fig. 4 the rectangles AB, GI-LOP and KL represent the horizontal projections of the lower orifices of the hoppers 6, 9, 13 and 7 respectively. The rectangles EF' and I] represent the horizontal projections of the lower orifices of hoppers, not shown, similar to hopper 9 and disposed respectively to the right and left of that hopper as viewed when looking toward the furnace from the outer end of the forebay extension 2. Rectangle MN represents the horizontal projection of the lower orifice of a hopper, not shown, corresponding to hopper 7 and disposed in spaced parallel relation to the hopper 7 at the right hand side thereof as viewed in Fig. 4.

The sheet 4 formed by the feeding arrangement 8 thereforehas its origin at AB, andw ill cover an area ABCD, its forward movement setting up the current b.

Located on either side of the feed roller 8, as viewed in Fig. 4, are two hoppers 13, one being shown in Fig. 3 and both being represented in Fig. 4 by the rectangles OP and QR. Owing to the current b, the materials leaving the hoppers 13 are carried forward and contin uously replaced on the glass by other materials, thus forming two further continuous sheets starting at OP and QR respectively, which travel along the sides of the sheet 4, which is also represented by ABCD.

Situated in front of the feeding roller arrangement 8 are two hoppers 7 represented in Fig. 4 by their lower orifices KL and MN respectively. The materials leaving these hoppers fall on to the sheets formed at AB, OP and QR and on the narrow strips of glass left exposed between them, and are subjected to the same forward movement. In proportion as they are carried forward, they are replaced by other materials leaving the hoppers 7, which also form two continuous sheets beginning at KL and MN respectively and progressing towards the interior of the furnace. In Fig. 3 these sheets are shown at and are therefore superposed on the sheet 4.

Finally, three other hoppers 9 are disposed to the rear of the feed roller 8. One of these is shown in Fig. 3 and the orifices of all three are represented in Fig. 4 by the shaded strips EF, GH and I]. Since the currents b also appear at this point, the materials leaving the hoppers 9 will travel along with the glass by which they are supported, and the hoppers 9 will also feed the sheet of material in proportion as it is carried away. Three continuous sheets will therefore again be started at EF, GH and II respectively. At the points at which these sheets, represented by 10 in Fig. 3, arrive at the points at which the sheets 4 and 5 are started, they are covered by the latter sheets.

Three superposed sheets 5, 4 and 10 are thus obtained, which progress simultaneously while floating on the glass.

To facilitate the continuous flow of the materials introduced through the hoppers 7, 9 and 13, a delivery regulating device can advantageously be fitted to the said hoppers, for example in the form of a mechanical or electromagnetic vibrator such as that illustrated at 14 for the hopper 9. With the aid of such a device, the materials are deposited on the glass in a regular manner, and since they are continuously carried away by the action of the currents b they are continuously renewed at the beginning of the sheet and thus ensure continuity of the said sheet.

The advantage of this method is that it is possible to feed the starting materials into the furnace from a number of separate lots with the aid of a single feeding roller type machine. These materials may be identical or different. Thus, for example, the cullet may be charged through the hoppers 9 and the batch through the other hoppers. In each case, the materials are kept strictly in the correct proportions, which would not be the case if there were a plurality of feeding arrange ments. In fact, when there are a plurality of feeding arrangements and one of them stops, the other which continue to work alter the ratio of the Weights of materials to be fed into the furnace, the effect of which is to change the composition of the glass. With the method according to the invention, on the other hand, if the single feeding arrangement stops, all the sheets of ma- ,terial stop at the same time and resume their progress at the same time as the feeding arrangement starts again.

In fact, the materials leaving the hoppers 7, 9 and 13 are held stationary as soon as the sheets which are formed thereby cease to progress, since only that quantity leaves each hopper at each instant which is necessary to replace that which has been carried forward under the action of the current b.

It will also be readily understood that the current I) is independent of the nature of the furnace-feeding arrangernent, and it is sufiicient for a given arrangement to impart to the batch deposited on the glass bath, impulses directed towards the furnace in order that this current b may automtically be set up and may be utilised in accordance with the present invention.

Fig. 5 shows by way of example the application of the method to a well-known furnace-feeding system differing from the feeding arrangement shown in Figs. 1 to 4.

The furnace-feeding arrangement shown in Fig. 5 comprises a push member 11 actuated with a reciprocating movement parallel to the surface of the glass. At each rearward movement of the push member, some of the batch emanating from the hopper 12 is deposited on the bath 3. In its forward movement, the push member 11 forces the materials before it, thus forming a practically continuous sheet 4 which progreses in steps. In order to apply the method according to the invention, a second device is provided for the introduction of a part of the materials, for example a hopper 15 provided with a vibrator 14 and containing materials which are deposited on the glass and are carried away in the forward direction by the action of the current b. In proportion as they are carried away, these materials are replaced be low the outlet of the hopper by fresh material issuing from the said hopper, and a further practically continuous sheet 10 is obtained, which moves forward with the current b and is covered by the sheet 4. The two superposed sheets 4 and 10 will move forward simultaneously.

Additional hoppers or spouts may also be disposed in front or at the sides of the push member 11 to provide an arrangement similar to that shown in Fig. 4.

It will further be understood that the arrangement of the hoppers as shown in Figs. 3 and 4 may be modified and that some of these hoppers may be omitted, modifications of this nature, for meeting requirements, coming within the scope of the invention.

We claim:

1. Apparatus for proportionally feeding different granular vitrifiable materials into a glass furnace, comprising a forebay of said furnace having spaced side walls and adapted to contain molten glass, a central hopper having a discharge opening extending transversely of the forebay and its ends spaced from the sides of the fore-, bay, an impeller under said central hopper and operable to impel material issuing from the hopper toward the furnace so as to cover with said one material a central portion of the glass surface as wide as the discharge opening of the central hopper and extending therefrom toward the furnace, said impeller being effective to create a surface current in the glass Wider than said central portion and flowing toward the furnace, and an auxiliary hopper having a discharge opening extending over a side portion of the glass surface extending parallel to said central portion, said side portion being subject to said surface current so that material issuing from said auxiliary hopper is fed toward the furnace at a rate proportional to the rate of feeding of material from the central hopper.

2. A method of feeding granular vitrifiable materials into a glass furnace in two superposed sheets on the surface of the molten glass, comprising the steps of depositing a first sheet of one material onto a portion of the surface of the glass, separately depositing on said lfirstsheet at a location removed in the direction of the furnace from where said first sheet was deposited a second sheet of a ditferentniaterial and narrower than said first sheet, impelling said second sheet toward said furnace and thereby setting up in the molten glass a surface current carrying both said sheets toward said furnace.

3. A method as claimed in claim 2, wherein at least the marginal portions of the first sheet consist of cullet and the second sheets consists of batch.

4. A method of feeding the materials as claimed in claim 2, including the step of depositing parallel longitudinal bands of other materials on other portions of the glass surface.

5. Apparatus for feeding vitrifiable materials in sheet form onto the surface of the molten glass in the forebay of a glass furnace, comprising a central hopper having a discharge opening extending transversely of the forebay and its ends spaced from the sides of the forebay, an impeller under said central hopper and operable to impel material issuing from the hopper toward the furnace, and at least one auxiliary hopper, each said auxiliary hopper having a discharge opening extending transversely 20 of the forebay between a side thereof and said central hopper.

6. Apparatus for feeding vitrifiable materials in sheet form onto the surface of the molten glass in the forebay of a glass furnace, comprising a central hopper having a discharge opening extending transversely of the forebay and substantially narrower than the forebay, an impeller under said central hopper and operable to impel material issuing from the hopper toward the furnace and a plurality of auxiliary hoppers laterally spaced from each other and each having a discharge opening extending transversely of the forebay and disposed intermediate said central hopper and the side of the forebay opposite the furnace, the discharge openings of said auxiliary hoppers extending over substantially the whole width of the forebay.

References Cited in the file of this patent UNITED STATES PATENTS 1,623,057 Kingsley Apr. 5, 1927 2,284,398 Kutchka May 26, 1942 2,711,837 Henry et al. June 28, 1955 FOREIGN PATENTS 466,139 Belgium June 22, 1946

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