JPH0228524B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a melting furnace for heating and melting thermoplastic materials. In melting ovens, particularly glass melting ovens, the electrodes are arranged in groups in separate heating zones, with opposing electrodes of each electrode group connected between the individual output terminals of the electrodes. This electrode group may be composed of two opposing electrodes in one group, and each opposing electrode may be composed of three electrodes, or in other forms. The prior art disclosed in US Pat. No. 3,440,321 uses a T-shaped Scott connection to apply voltage to two groups of opposing electrodes in a melting oven. In this patent specification, two heating regions each consisting of two electrode groups are shown, each adjacent electrode group being connected in a T-shaped Scott connection. The problem with this prior art is that U.S. Patent No.
Adjacent electrode groups, as shown in US Pat. No. 3,440,321, must be physically separated significantly to prevent the formation of crossfires and undesirable electrical paths between electrodes of different electrode groups. There is a particular thing. Increasing the number of heating zones in the melting furnace therefore poses a problem, limiting the amount of heat that can be input into the electric furnace. According to the invention, groups of opposing electrodes are arranged in a plurality of heating zones of a melting oven. These regions are placed closer to each other than previously possible. A first electrode group is provided in the first heating region, and includes a first electrode and a second electrode facing each other so as to form a heating path therebetween. A second heating region adjacent to the first heating region is provided with a second electrode group including a first electrode and a second electrode facing each other so as to form a heating path with each other.
The first electrode of the second electrode group is located adjacent to the first electrode of the first electrode group. and,
The power source causes the first electrode group of the first and second electrode groups to
An in-phase signal is applied to each of the electrodes of the groups, and an out-of-phase signal is applied to each of the second electrodes opposite each of the first electrodes of both groups. The electrodes can be connected between the terminals of a two-phase or three-phase transformer by means of a T-shaped Scott connection to substantially confine the current to a preferred path between the opposing electrodes. Melting furnaces are used to melt glass or other materials with heat due to the Joule effect. arranging the electrodes according to the principles of the invention;
And by connecting these electrodes to a power source,
Compared to the prior art, it is possible to increase the number of heating zones within a given area of a given melting oven. According to the invention, the distance between adjacent electrode groups of two separate and different heating regions can be made very small in practice. This distance is limited by practical considerations of the amount of heat generated by the electrodes and the maximum current density. For example, the center-to-center distance between adjacent electrodes may be approximately 5 to 6 times the electrode diameter. When 76.2 mm (3 inch) electrodes are arranged in one group, the center-to-center distance between each group's nearest or adjacent electrode is
It can be about 38.1 to 45.7 cm (15 to 18 inches). The advantage of a very long electrical path is obtained by significantly increasing the distance between opposing electrodes that are arranged to form a heating path. For example, this distance is approximately
It can be about 3m. As mentioned above, in the arrangement according to the invention, a potential difference is created between adjacent electrode groups that can form an undesired heating path, but the molten material along this undesired heating path has a high resistance.
Moreover, even if a current flows, it is small, so that it can be said that substantially no current flows through this undesirable heating path. Next, specific embodiments of the present invention will be explained with reference to the drawings. In FIG. 1, the first electrode group consists of a first electrode B1 and a second electrode A1, and the second electrode group consists of a first electrode B2 and a second electrode C2. In FIG. 2, the first electrode group consists of a first electrode B1 and a second electrode A1, and the second electrode group consists of a first electrode B2 and a second electrode A2. In FIG. 3, the first electrode group is the first electrode B.
The second electrode group consists of the first electrode B5 and the second electrode C5. In the plan view of the melting furnace shown in FIG.
The electrode groups C3-A3 and C6-A6 are placed in the heating region 3. The electrode groups shown in FIGS. 1, 2 and 3 have at least two electrodes or can have a plurality of electrodes. That is, for example, the electrode A1 may be composed of a plurality of electrodes, for example, four electrodes arranged in a rectangular, square, or other suitable shape. The direction of flow in the melt kiln is indicated by arrows, but this is not important to the invention. The transformers shown in FIG. 1 for applying voltage to each electrode are transformers T1 and T2. Transformers T1 and T2
is connected to a three-phase power supply having terminals A, B and C. On the output side of the transformer, output terminal A1,
B1, C2, B2, A3, C3, A4, B4, B
5, C5, A6 and C6 are connected to each electrode group as indicated by corresponding electrode symbols. For example, terminals A1 and B1 of transformer T1
is connected to electrode group A1-B1, and electrode A
The electrical path from 1 to B1 passes through region 1. Similarly, terminals A3 and C3 of transformer T1 are connected to electrode group A3-C3. By using the three-phase system shown in Figure 11,
The undesired current becomes essentially zero. Preferred heating passages are as follows. Area 1 A1-B1, A4-B4 Area 2 B5-C5, B2-C2 Area 3 C3-A3, A6-C6 This melting kiln extends from the outer end limit of area 1 shown as ``1'' to the outer end limit of area 1 shown as ``3''. Almost the entire area up to the outer limit of area 3 is filled with electrical circuits. Only a small amount of spacing or voids exist between the heated regions. A void or empty space is a space between adjacent electrode groups, for example, a space between electrode B4 and electrode B5, electrode B1 and electrode B2, electrode C2 and electrode C3, and electrode C5 and electrode C6. Department. Such gaps, which create undesirable electrical paths, can be made very small given practical considerations of the maximum permissible current density of the electrodes and the heat generation. For example, the center distance between adjacent electrodes can be about 5 to 6 times the electrode diameter. This distance does not represent a limitation of the invention, but is provided as an example of practical considerations for melting furnace design and electrode location. This same concept applies to the distance between electrodes in groups of electrodes connected in parallel to a common power supply. For example, if electrode B4 has four electrodes commonly connected to a single power source and placed in a rectangular configuration, the interelectrode distances should be as described above with similar practical considerations for heat generation. limited. There is a potential difference between the electrode groups that can create an undesired heating path, but the molten material along this undesired heating path has a high resistance and a small current flows through it. It can be said that virtually no current flows. The electrodes are connected such that the current between adjacent electrodes is substantially zero. In this regard, adjacent electrodes include current B4, electrode B5, and electrode B1.
and electrode B2, electrode C2 and electrode C3, and electrode C5 and electrode C6. FIG. 2 shows a two-phase power supply for the electrodes, in which Scott type electrical connections are used;
Each electrode is connected to a terminal of the transformer as indicated by a corresponding electrode symbol. The preferred heating path in FIG. 2 includes electrode groups A1-B1 and electrode group D1 in heating zone 1.
-C1, electrode group D2 in heating area 2-C2
and electrode group A2-B2 and electrode group A3-B3 and electrode group C3-D3 in heating region 3. As shown in FIG. 2, each heating area is in close proximity to other heating areas. That is, the heating area 1 is adjacent to the heating area 2, and the heating area 2 is adjacent to the heating area 3, and a plurality of The heating areas are separated by voids for practical considerations as already mentioned in connection with FIG. The flow of material in the melting kiln is in the direction of the arrow.
However, it is not necessary to carry the material in the direction of this arrow in the kiln in the practice of the invention. In this embodiment, as well as the embodiment shown in FIG. 1, no current flows between the heating regions. A modification of the embodiment shown in Fig. 1 is shown in Fig. 3. Here, the transformer shown in Fig. 1 is used, but the connection between the transformer and the electrodes corresponds to that shown in Fig. 3. The electrode symbol is as shown below. That is,
For example, in the heating region 1, the output terminals A1 and B1 of the transformer T1 are connected to the electrodes A1 and B1, respectively.
Connected to 1. Similarly, transformer terminals A3 and C3 are connected to electrodes A3 and C3 in heating zone 3, respectively, and transformer terminals C2 and B2
are electrodes C2 and B2 in heating region 2, respectively.
It is connected. Output terminals A4 and B4 of transformer T2 are connected to electrodes A4 and B4, respectively, in heating zone 1, output terminals B5 and C5 are connected to electrodes B5 and C5, respectively, in zone 2, and output terminal A6 and C6 are connected to electrodes A6 and C6, respectively. Preferred heat generation paths include electrode groups A1-B1 and A4-B4 in heating zone 1, electrode groups B5-C5 and B2-C2 in heating zone 2, and electrode groups C3-A3 and C6-A6 in heating zone 3. It is. Similar to the embodiment shown in FIG.
There is a potential difference between the electrode groups that can create an undesired heating path, but the molten material along this undesired heating path has a high resistance and a small current flows through it. It can be said that virtually no current flows. As shown, heating regions 1, 2 and 3 are each adjacent to at least one other region. That is, since heating area 1 is provided adjacent to heating area 2 and heating area 2 is provided adjacent to heating area 3, the same practical considerations as described in connection with FIG. 1 are used to minimize the gap between the heating areas. With this state in place, an electrode heating path is formed in the length direction of the melting furnace from end "1" to end "3". As with the embodiments of FIGS. 1 and 2, material flow is provided in the direction of the arrows, although this direction is not essential to the practice of the invention. The aim of the invention is to increase the length of the heating path and at the same time to minimize the area in the oven that is free of electrodes and heating paths. By increasing the heating path between the electrodes, as specifically shown in FIGS. 1 and 2, where the heating path diagonally traverses the heating area, the resistance between the electrodes increases and each heating area The power per unit current increases. The lines drawn through the heating passages of the three heating regions shown in FIGS. 1 and 2 are Z-shaped (dotted lines from electrode A1 to electrode B1, electrode B2 to electrode C2 and electrode C3). The line from to electrode A3 draws the letter Z, and from electrode A4 to electrode B
4. Electrode B5 to electrode C5 and electrode C6 to electrode A6 also draw the letter Z). Therefore,
In each heating zone, the lines drawn through the heating passages of the electrodes in FIGS. 1 and 2 resemble the letter X. The lines drawn between electrodes A1 and B1 and electrodes B4 and A4 in heating area 1 in FIG. 1 are the same as the lines drawn between the electrical circuits in heating areas 2 and 3 in FIGS. 1 and 2. Similarly, it is X-shaped. Similarly, the line drawn between the electrical paths of one electrode group in each of two adjacent heating regions is V-shaped. That is, a line drawn from electrode A1 to electrode B1 and a line drawn from electrode B2 to electrode C2 form a V-shape in two adjacent heating areas, heating area 1 and heating area 2. The transformer is interconnected with adjacent electrodes of adjacent regions such that the same phase is applied to adjacent electrodes and different phases are applied to corresponding counter electrodes of each of the adjacent electrodes. As shown, phase AB is connected to electrode group A1, B1 of heating zone 1, and phase BC is connected to electrode group B2, C of heating zone 2.
Connected to 2. Adjacent electrodes B2 and B
1 are connected to the poles of the same phase, while electrodes A1 and C2 are connected to phases A and C, respectively. This pattern is similar to the heating passage B2-
C2 and A3-C3, heating passage A4-B4 and B5-
C5 and heating passages B5-C5 and C6-A6 follow. In FIG. 3, the heating passages are on both sides of the length, and the individual heating passages do not intersect with each other. This arrangement and phase relationship causes the floor or bottom wall of the melting oven from end "1" to end "3" to be substantially filled with heating zones, forming heating passages in each heating zone. , each heating region will be separated from the other heating regions by a very small air gap between adjacent electrodes. As described in detail above, according to the present invention, a plurality of heating regions can be arranged extremely close to each other in a melting furnace, and the current between uncombined electrodes can be reduced to substantially zero. Furthermore, since it is not necessary to widen the interval between heating regions in the melting furnace, the amount of heat supplied to the thermoplastic material can be increased. Moreover, since a power source is connected to the electrodes of each electrode group so that the electrodes are not shared between the electrode groups, it is possible to prevent the life of a specific electrode from being shortened.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the arrangement relationship between regions and electrodes of a melting furnace having a three-phase power supply, which shows one embodiment of the present invention, and FIG. 2 shows a melting furnace having a two-phase power supply, which shows another embodiment of the present invention. FIG. 3 is a schematic explanatory diagram showing the arrangement relationship between the area of the kiln and the electrodes, and FIG. 3 is a schematic explanatory diagram similar to FIG. 1 but showing a modified form. A1-A6, B1-B6, C1-C6, D1-
D3... electrode group, T1, T2... transformer,
"1", "3"... end.

Claims (1)

[Claims] 1. A first electrode group comprising a container containing a thermoplastic material, and a first electrode and a second electrode placed in the container and facing each other so as to form a heating path therebetween. and a second electrode group placed in the container and comprising a first electrode and a second electrode facing each other so as to form a heating path with each other, the first electrode of the second electrode group being a first electrode of the first electrode group; and a power source, the power source being located close to the first electrode of the first and second electrode groups.
In-phase is applied to each of the electrodes, and the first
A thermoplastic characterized in that a different phase is added to each second electrode corresponding to each of the electrodes, and each electrode group is connected to the first and second electrodes of each electrode group so that the electrodes are not shared. A kiln for heating and melting materials. 2. The melting furnace according to claim 1, wherein the power source is a three-phase power source. 3 the first and second electrodes of the first electrode group;
and the distance between the first and second electrodes of the second electrode group are less than the distance between the first electrode of the first electrode group and the first electrode of the second electrode group. The melting furnace according to claim 1, which is large in size. 4 the first and second electrodes of the first electrode group;
2. The melting furnace according to claim 1, wherein the electrode and the first and second electrodes of the second electrode group each have a plurality of electrodes.