JPS6222660B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hot air circulation baking furnace used for manufacturing wire rods, strips, tubes, etc. (hereinafter referred to as wire rods) having enamel coatings or other synthetic resin coatings.

As is known, a wire having an enamel coating or the like is baked in a furnace to harden the coating. At this time, the coating before the baking process contains a highly volatile and combustible solvent, and the concentration of the vaporized solvent increases in the furnace, causing an explosion.
This will reduce the quality of the wire coating. Therefore, a portion of the hot air in the furnace is exchanged with fresh air, and through this heat exchange, harmful components contained in the exhaust gas discharged to the outside are treated.

More specifically, in this kind of conventional baking furnace, the wire passing through the inside is heated by an electric heater placed in the wire passage in the furnace, and at this time, an appropriate amount of air is injected into the wire passage from the air inlet. In addition to introducing fresh air, a portion of the hot air in the wire passage is discharged to the outside from the exhaust port, and when exhausting, harmful components in the hot air are reduced to standard values through chemical treatment using a catalyst or combustion treatment. It was processed as below.

In the conventional example as well, the concentration of vaporized solvent in the furnace is reduced by introducing fresh air, and the exhaust gas is treated, so that the above-mentioned problems such as explosion accidents and pollution can be solved.

However, in order to improve thermal energy efficiency in the conventional example, even if the exhaust gas treated as described above is reused as hot air for baking the wire coating, the temperature of this exhaust gas is considerably higher than the baking temperature, so it is difficult to reuse it. It was necessary to introduce a large amount of air to bring the temperature down to the baking temperature, which made it difficult to control the temperature inside the furnace.

In addition, since hot air is discharged outside the furnace in proportion to the amount of air introduced, the effective use of thermal energy cannot be measured, and the large amount of hot air discharged due to the introduction of a large amount of air causes new hot air pollution. It was becoming a thing.

In view of the above-mentioned problems, the present invention is a baking furnace that circulates hot air in the furnace and performs purification treatment, which eliminates thermal energy loss, improves controllability of furnace temperature,
This system is designed to prevent hot air pollution, and its configuration will be explained below with reference to illustrated embodiments.

In FIGS. 1 to 3, 1 is a baking furnace whose main material is, for example, a heat-resistant steel plate, and a heat insulating material is attached to the outer wall surface of the baking furnace. A hot air treatment passage 3, a hot air outgoing path 4, and a hot air return path 5 are provided, respectively.

The above-mentioned wire rod passage 2 consists of an outer passage part 6 which is straight in the longitudinal direction, and an inner passage part 7 which is inside the outer passage part 6 and is slightly shorter than the same passage 6. A wire inlet part 8 and a wire outlet part 9 are provided at both ends in the longitudinal direction.
Air inlets 12, 12', 13, 13' having butterfly-shaped on-off valves 10, 10', 11, 11' are provided near both parts 8, 9, while the inner The furnace wall 14 constituting the passage section 7 is made of a steel plate surface-treated with a material that has a far-infrared radiation effect, such as a metal oxide, and openings at both ends are aligned with the wire inlet section 8 and the wire outlet section 9. We are doing so.

Furthermore, the hot air processing passage 3 has a linear air inlet section 15 and a hot air outlet section 16 at both ends thereof.
A heater 17 using a combustion burner, an oxidation catalyst processor 18, and an air blower 19 are arranged between 5 and 16, and an exhaust port 21 having a butterfly-shaped opening/closing valve 20 is provided at the tip side of the hot air outlet section 16. is formed.

Further, a hot air outward path 4 and a hot air return path 5 are provided to connect the wire passage 2 and the hot air treatment passage 3. location (the one shown is the central part) and the linear air inlet section 1 of the hot air processing passage 3
5 are in communication with each other, and the hot air outgoing path 4 connects a part or several locations in the longitudinal direction of the outer path section 6 of the wire passage 2 (the one shown is the central portion) and the hot air outlet section 16 of the hot air processing path 3. The sides communicate with each other.

In the figure, 22 is a motor that drives the blower 19;
23 is a wire rod.

In the present invention consisting of the above-described embodiment, when the baking furnace 1 starts operating, the air inlets 12, 12', 1
3, 13' and each on-off valve 10, 1 of the exhaust port 21
0', 11, 11', and 20 are closed, the heater 17 is brought into a combustion state, and the blower 19 is rotated to circulate hot air at a predetermined temperature across both passages 2 and 3. 23 is made to run from the wire inlet part 8 of the wire rod passage 2 to the inner passage part 7 and further from the inner passage part 7 to the wire outlet part 9, and while the wire rod 23 passes through the inner passage part 7, hot air is passed through the wire rod 23. The film is baked with hot air.

At this time, in the baking furnace 1, the heated air is heated to a predetermined temperature by the heater 17 and the oxidation catalyst treatment device 18 on the hot air inlet 15 side of the hot air treatment passage 3, and the purified hot air is passed through the hot air outlet 16. It enters the outer passage 6 of the wire rod passage 2 via the outward passage 4, and further from the outer passage 6 to the inner passage 7, and from the inner passage 7 to the hot air return passage 5 to the hot air inlet portion 15 of the hot air treatment passage 3. The hot air enters, and the hot air circulation described above is repeated.

On the other hand, when the exhaust port 21 of the hot air processing passage 3 is opened by the on-off valve 20 during the above hot air circulation,
A part of the hot air is discharged to the outside, and when each air inlet 12, 12', 13, 13' is opened by the on-off valves 10, 10', 11, 11', the inside of the wire passage 2 is released. fresh air is introduced.

Of course, since the hot air discharged to the outside in the above process is treated by the oxidation catalyst treatment device 18, the concentration of the vaporized solvent in the coating is extremely low and is not harmful.

For reference, the temperature of each part inside the furnace during baking of the wire is shown as follows: The temperature at which the hot air is treated by the oxidation catalyst treatment device 18 is 550 to 650°C, the baking temperature of the wire coating is 350 to 500°C, and the former is higher than the latter. Therefore, the temperature of the hot air that enters the wire rod passage 2 side from the hot air outlet part 16 of the hot air treatment passage 3 via the hot air outgoing passage 4 is higher than
Although the baking temperature is higher than the above baking temperature, the hot air entering the wire rod passage 2 does not directly enter the inner passage 7 of the same passage 2, but first passes through the outer passage 6.
While this hot air passes through the outer passage 6, part of its thermal energy is absorbed by the furnace wall 14, causing heat transfer to the internal hot air, so that when it reaches the inner passage 7, it is close to the baking temperature. The temperature will drop to

Further, since the surface of the furnace wall 14 heated by the hot air passing through the outer passage section 6 is treated with metal oxide, far infrared rays are emitted from the furnace wall 14 toward the inner passage section 7. Therefore, the wire rod 23 and the internal hot air that receive far infrared rays in the inner passage 7 are baked into a film in a short time and with a good finish due to the synergistic effect of the far infrared rays and the hot air. .

In addition, in the above embodiment, the heater 17,
The oxidation catalyst treatment device 18 serves as high temperature gas treatment equipment.
This high-temperature gas processing equipment may be a direct combustion type high-temperature combustion burner (combustion temperature 700-750°C).

As explained above, in the baking furnace 1 of the present invention, the wire passage 2 consists of the outer passage part 6 and the inner passage part 7, and
The inner passage 7 is constituted by a furnace wall 14, and this wire passage and high temperature gas processing equipment (for example, 17, 1
8) Since the hot air processing passage 3 having the air blower 13 is connected to the hot air processing passage 3 via the hot air outgoing path 4 and the hot air returning path 5 so that the hot air can be freely circulated, the hot air can be circulated within the baking furnace 1. is constantly purified by the high-temperature gas treatment equipment, and therefore the concentration of vaporized solvent from the coating on the wire in the wire passageway 2 can be suppressed.

Furthermore, since the concentration of vaporized solvent in the wire passageway 2 is suppressed, frequent or large amounts of hot air exchange are not required, and therefore the hot air temperature distribution in the wire passageway 2, which is once maintained at a predetermined temperature, is not disturbed. Moreover, since the amount of hot air discharged into the furnace is extremely small, the effective amount of hot air can be increased at all times, and energy loss and hot air pollution caused by the discharged hot air (a small amount) can also be eliminated.

Furthermore, the processing temperature of the high-temperature gas processing equipment mentioned above is higher than the temperature at which the wire coating is baked, and the temperature obtained by the processing equipment can heat the hot air inside the furnace and maintain the temperature, so a separate heat source is required. For example, if an electric heater or the like is inserted in the wire passage 2, the waste will be eliminated, and even if the hot air treatment temperature does not match the temperature at the time of baking, the hot air will pass through the outer passage 6 and pass through the inside. Road section 7
During this period, the thermal energy of the hot air is partially absorbed by the furnace wall 14 and the temperature is lowered to approximately the baking temperature. Therefore, there is no need to adjust the temperature by introducing a large amount of air, and therefore the temperature controllability is improved. becomes easier,
The amount of hot air discharged can also be reduced.

Therefore, according to the present invention, energy saving, pollution prevention, furnace temperature controllability, etc. can all be satisfactorily ensured.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view showing one embodiment of the baking furnace of the present invention, Fig. 2 is a sectional view taken along the line shown in Fig. 1, and Fig. 3
The figure is a sectional view taken along the line of FIG. 1. 1... Baking furnace, 2... Wire rod passage, 3... Hot air processing passage, 4... Hot air outward path, 5... Hot air return path, 6...
...Outer route section, 7...Inner route section, 8...Wire rod entrance section, 9
...Wire rod outlet section, 14...Furnace wall, 15...Hot air inlet section, 16...Hot air outlet section, 17...Heater as high temperature gas processing equipment, 18...Oxidation catalyst treatment as high temperature gas processing equipment Container, 19...Blower, 2
3...Wire rod.

Claims (1)

[Scope of Claims] 1. A hot air heating type wire rod passage for heating a wire having a coating to be baked has an outer path portion having a wire inlet portion and a wire outlet portion at both ends in the longitudinal direction, and an inner portion of the outer path portion. In this case, the openings at both ends in the longitudinal direction have an inner passage portion corresponding to the inside of the wire inlet portion and the wire outlet portion, and the hot air in the wire passage is introduced into the inner passage to treat the hot air as exhaust gas. The processing passage has a hot gas processing equipment and a blower between its hot air inlet and hot air outlet, and the inner passage and the hot air inlet of the hot air processing passage are connected to each other by a hot air return path,
A hot air circulation type baking furnace characterized in that the outer passage portion and the hot air outlet side of the hot air processing passage are connected to each other by an outgoing hot air passage. 2. The hot air circulating baking furnace according to claim 1, wherein the furnace wall constituting the inner passage is made of an object such as a steel plate whose surface has been treated with metal oxide or the like to increase the infrared emissivity.