JPH11248347A - Drying furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the labor required for cleaning the inside of a drying furnace, such as the drying furnace for painting, drying furnace for printing, etc., and, at the same time, to reduce the burden of an exhaust gas treating device. SOLUTION: A water electrolysis accelerating material 16 prepared by kneading the powder of a pyroelectric material with a heat-resistant organic adhesive is applied to the exposed internal surface 14 of the furnace casing 2, such as the furnace wall, etc., of a drying furnace. When the material 16 is heated as the temperature in the furnace rises, minus electric charges appear on the exposed internal surface 14 of the furnace casing 2 due to the pyroelectric effect of the material 16. When an evaporated organic solvent which is produced at the time of drying the coating film is condensed on the exposed internal surface 14 of the furnace casing 2, etc., and the condensed solvent adheres to the surface 14, etc., as gum, part of water molecules contained in the gum receives the electrons which appear due to the pyroelectric effect of the material 16 and electrolyzed into hydrogen and ionized oxygen. Since the ionized oxygen reacts to the organic matter which is the main component of the gum and dissolves the organic matter into water and carbon dioxide through oxidation, the quantity of the gum can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying furnace used for drying a paint applied to an object to be coated such as an automobile body, and for drying a printing ink printed on paper or plastic.

[0002]

2. Description of the Related Art For example, in a car body coating line, a drying oven for drying a coating film is provided at a stage subsequent to a coating booth for spraying a coating material. While transporting on a conveyor,
The coating film formed on the surface is dried.
Since the drying furnace is maintained at a temperature of about 100 to 160 ° C. and evaporates the moisture and organic solvent contained in the paint to dry and harden the coating film, the concentration of the organic solvent in the furnace gradually increases, If left untreated, the organic solvent contained in the contaminated air will agglomerate on the surface of the object to be coated such as an automobile body, causing the original color of the coating to fade, resulting in a coating defect called yellowing. For this reason, in a general drying furnace, contaminated air (exhaust gas) is always discharged from the inside of the furnace, and after being purified by an exhaust gas treatment device, the contaminated air (exhaust gas) is circulated and supplied into the furnace or discharged to the atmosphere. .

[0003]

However, since the contaminated air convects inside the furnace before being discharged to the outside, the evaporated organic solvent contained in the contaminated air is removed from the side wall, the ceiling wall, the floor wall, and the partition. Agglomerates on exposed surfaces in the furnace, such as walls,
There was a problem that it adhered as a stain. In particular, if the tar attached to the ceiling wall grows, it will splatter on the object to be coated, resulting in poor coating. To prevent this, usually every two to three weeks, depending on the type of paint used, Must clean the inside of the furnace every week. In addition, the drying oven for painting the body of an automobile has a total length of more than one hundred and several hundred meters, and the cleaning operation has to rely on manual labor, so that a great deal of labor is required, and the cost required for the cleaning operation is increased. .

Further, the drying furnace for coating has a large volume due to its long overall length, and the exhaust gas treatment device has to purify a large amount of exhaust gas continuously discharged from the drying furnace. However, there is a problem that maintenance costs and running costs required for exchanging consumables and cleaning the inside of the duct leading to the exhaust gas treatment device are increased. Although the drying oven for printing is not as good as the drying oven for coating, the organic solvent component evaporates from the printing ink in common with the drying oven for coating. The same is true.

Accordingly, the present invention reduces the labor required for cleaning operations in a drying oven such as a coating drying oven or a printing drying oven, and reduces the load on an exhaust gas treatment apparatus, thereby significantly reducing maintenance costs and running costs. Reduction is a technical issue.

[0006]

SUMMARY OF THE INVENTION To solve this problem, the present invention relates to a drying furnace in which contaminated air containing an evaporated organic solvent is generated by drying a work in the furnace, and a surface of the furnace inside the furnace is provided. Alternatively, a water electrolysis accelerating material obtained by kneading a pyroelectric material powder with a heat-resistant inorganic adhesive is coated on an inner surface of a duct through which air in the furnace flows.

In the drying furnace according to the present invention, for example, when an automobile body coated with a paint containing an organic solvent is carried into the furnace body and heated, the coating film is dried and hardened. At this time, since the exposed surface of the furnace body and the inner surface of the duct through which the air in the furnace body flows are coated with a water electrolysis accelerating material obtained by kneading a pyroelectric material powder with a heat-resistant inorganic adhesive, When the pyroelectric material is heated, a negative charge appears on the exposed surface in the furnace or the inner surface of the duct due to the pyroelectric effect. On the other hand, when the work is heated, moisture and organic solvent evaporate from the undried coating film,
With the convection of the air in the furnace, this adheres and aggregates on the exposed surface and the inner surface of the duct to form a dust. The molecules of water contained in the tar can receive electrons appearing by pyroelectric effect, some ^{_{of, H 2 O + 2e - →}} O 2- + H 2 H 2 O + e - → O - + the reaction represented by H _2, is electrolyzed into hydrogen and ionized oxygen. Then, the ionized oxygen reacts with an organic substance which is a main component of the tar adhering to the exposed surface in the furnace, oxidizes it, and decomposes it into water and carbon dioxide.
Accordingly, since the tar attached to the exposed surface in the furnace body is gradually decomposed and reduced in weight, the frequency and labor of the cleaning work are reduced, and the load on the exhaust gas treatment device is also reduced. , Running costs are reduced.

Further, in another drying furnace according to the present invention, a ceramic powder containing a radioactive element is kneaded with a heat-resistant inorganic adhesive on an exposed surface in a furnace or on an inner surface of a duct through which air flows in the furnace. Oxygen activator is applied. According to this drying furnace, water molecules contained in the tar attached and coagulated on the exposed surface of the furnace and the inner surface of the duct are converted from radioactive elements contained in the oxygen activator coated on the exposed surface of the furnace, etc. radiation is irradiated, some of which are separated _{3H 2 O → O 3 + 3H} 2 2H 2 O → O 2 + 2H reaction with water is hydrogen and oxygen that is represented by _2, resulting oxygen and ozone Can be Therefore, these oxygen and ozone react with the organic matter which is the main component of the tar, oxidize it and decompose it into water and carbon dioxide, and the tar adhering to the exposed surface in the furnace and the inner surface of the duct gradually disappears. Decomposed and reduced in weight.

[0009]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an explanatory view showing a drying furnace according to the present invention, and FIG. 2 is a schematic view showing a chemical change in the furnace. For convenience of explanation, in FIG. 1, the right side shows a radiant heating zone for heating the inside of the furnace with a dark red panel, and the left side shows a convection heating zone for blowing the hot air to heat the inside of the furnace.

The drying furnace 1 according to the present embodiment is used as a drying furnace for coating an automobile body, and is provided continuously to a coating booth (not shown).
A conveyor 3 for transporting an automobile body is laid along the longitudinal direction. A radiant heating zone 4A for drying the undried coating film to a completely dry state is formed on the front side of the drying furnace 1, and a convection heating for baking and drying the coating film dried in the radiant heating zone 4A is provided on the subsequent stage. Zone 4
B is formed.

The radiant heating zone 4 A is provided with a dark red panel 6 to which hot air is circulated and supplied from a hot air generator 5, and the inside of the furnace body 2 is heated by the radiant heat of the dark red panel 6. In the convection heating zone 4B, a hot air circulating system 10 for heating hot air sucked from the hot air suction duct 7 by the heat exchanger 8 and then blowing it out of the hot air blowing duct 9 is provided.
Are formed in the furnace body 2, and a gate-type partition wall 2 for preventing the hot air blown out from the hot air blowing duct 9 from flowing laterally.
P is formed at predetermined intervals. Reference numeral 12 denotes an exhaust gas suction duct for discharging contaminated air generated in the furnace body 2;
Reference numeral denotes an exhaust gas treatment device for purifying contaminated air (exhaust gas) discharged through the exhaust gas suction duct 12.

Then, the left and right side walls 2 L and 2 in the furnace body 2
R, ceiling wall 2U, floor wall 2F, partition wall 2P, dark red panel 6
, Outer surfaces of the hot-air suction duct 7 and the hot-air outlet duct 9, etc., inside the furnace body 2, each of the ducts 7 and 9 of the hot-air circulation system 10, and an inner surface 15 of the exhaust gas suction duct 12.
A water electrolysis accelerator 16 obtained by kneading a pyroelectric material powder with a heat-resistant inorganic adhesive is applied.

Here, examples of the pyroelectric material include tourmaline (tourmaline), quartz (SiO ₂ ), lithium tantalate (LiTaO ₃ ), and lead titanate (PbTi).
O ₃ ), PZT porcelain (lead zirconate titanate: PbZ)
Any material that produces a pyroelectric effect at the temperature inside the drying furnace, such as a solid solution of rO ₃ and PbTiO ₃ , can be employed. Also, feldspar and zircon (Zr) were added to quartz (SiO ₂ ).
A mixed powder obtained by mixing at least one of SiO ₄ ) and titanium oxide (TiO ₂ ) may be used. Each of these pyroelectric materials exhibits a pyroelectric effect when heated to about the ambient temperature of a drying furnace, and charges appear on the surface.

As the inorganic adhesive constituting the water electrolysis accelerating material 16, a heat-resistant inorganic adhesive which exhibits a bonding strength in a low-temperature treatment (500 ° C.) such as water glass or colloidal silica or colloidal alumina is used. Used. And
The water electrolysis accelerating material 16 obtained by kneading the above pyroelectric material powder with the heat-resistant inorganic adhesive is used to form the exposed surface 14 in the furnace body 2 and the ducts 7, 9, 12 through which the air in the furnace body 2 flows. Inner surface 1
5 is coated on the surface of the steel plate 17 with a thickness of 10 μm to 1 mm. The method of coating may be spraying by air atomization or coating with a roll coater or the like. The water electrolysis accelerator 16
And the steel plate 17 have different thermal expansion coefficients.
When the coating 6 is applied thickly, if the coating is not applied uniformly to the entire surface of the steel plate 17 but is applied discontinuously, the water electrolysis promoter 16 may be cracked even if the steel plate 17 is thermally expanded. There is no.

The above is an example of the configuration of the present invention, and its operation will be described below. When the drying furnace 1 is started and the inside of the furnace body 2 rises to a predetermined drying temperature, the automobile body to be the work W is conveyed by the conveyor 3 and the coating film is dried. At this time, the moisture and the organic solvent contained in the coating film evaporate, and the convection of the air in the furnace body 2 causes the ceiling wall 2U, the left and right side walls 2R and 2L, the floor wall 2F, the partition wall 2P, the dark red panel. 6 and the outer surfaces of the hot-air suction duct 7 and the hot-air outlet duct 9 such as the outer surfaces of the hot-air blow-out duct 9.
2 circulates and adheres and agglomerates on the inner surface 15 thereof to form tar.

On the other hand, the exposed surface 14 in the furnace 2 and the inner surface 15 of each of the ducts 7, 9, 12 are coated with a water electrolysis accelerating material 16 obtained by kneading a pyroelectric material powder with a heat-resistant inorganic adhesive. When the pyroelectric material contained therein is heated,
Due to the pyroelectric effect, charges appear on the exposed surface 14 in the furnace body 2 and on the inner surfaces 15 of the ducts 7, 9, and 12. Here, the water molecules contained in the tar attached to the exposed surface 14 and the inner surface 15 of the duct 12 receive the electrons appearing on the surface of the water electrolysis accelerating material 16, and a part thereof is H ₂ O + 2e ⁻ → O ²⁻ + H ₂ H ₂ O + e ⁻ → O ⁻ + H ₂ is used to electrolyze into hydrogen and ionized oxygen. Then, the ionized oxygen reacts with an organic substance, which is a main component of the tar attached to the exposed surface 14 and the like in the furnace body 2, and oxidizes this to decompose into water and carbon dioxide.

Accordingly, since the tar adhering to the exposed surface 14 in the furnace body 2 and the inner surface 14 of the duct 12 is gradually decomposed and reduced in weight, the frequency and labor of the cleaning operation are reduced accordingly, and The load on the exhaust gas treatment device 13 is also reduced, and maintenance costs and running costs are reduced.

In place of the water electrolysis promoter 16, ceramic powder containing a radioactive element is kneaded with a heat-resistant inorganic adhesive on the exposed surface 14 in the furnace body 2 and the inner surfaces 15 of the ducts 7, 9, and 12. It may be a case in which the applied oxygen activator 18 is applied. Thorium (Th),
Uranium (U), actinium (Ac), neptunium (Np) and the like are used.

In this case, from the radioactive element contained in the oxygen activator applied to the exposed surface 14 and the like in the furnace body 2, the dust adhered and coagulated on the exposed surface 14 in the furnace body 2 and the inner surface 15 of the duct 12. and radiation is irradiated to a molecule of water contained in, some of the water is separated into hydrogen and oxygen by the reaction expressed by _{3H 2 O → O 3 + 3H} 2 2H 2 O → O 2 + 2H 2 To obtain oxygen and ozone. Therefore, these oxygen and ozone react with the organic matter which is the main component of the tar, oxidize and decompose it into water and carbon dioxide, and adhere to the exposed surface 14 in the furnace body 2 and the inner surface 15 of the duct 12. The dried tarnish is gradually decomposed and reduced in weight.

A water electrolysis accelerator 16 in which pyroelectric material powder is kneaded with the heat-resistant inorganic adhesive, and an oxygen activating material 18 in which ceramic powder containing a radioactive element is kneaded with heat-resistant inorganic adhesive are used. Instead of coating, paste a water electrolysis promotion tile made of ceramic that is obtained by kneading and firing a pyroelectric material powder, or an oxygen-activated tile made of ceramic containing a radioactive element with an inorganic adhesive or the like. May be provided. In this way, if the tiles are used, the quality can be maintained at a constant level by manufacturing the tiles industrially. There is an advantage in that no coating unevenness occurs and anyone can finish uniformly. In this case, it is desirable to fill the tile joint with a heat-resistant and elastic filler so that the joint is not clogged.

[0021]

As described above, according to the present invention, the moisture contained in the tar attached to the exposed surface in the furnace and the inner surface of the duct is decomposed into hydrogen and oxygen, and the oxygen is used to separate the water from the tar. Organic components are oxidized and decomposed into water and carbon dioxide.As a result, the amount of tar attached to the surface is reduced naturally, reducing the frequency and effort of cleaning work, and at the same time reducing the load on exhaust gas treatment equipment. This leads to a very excellent effect that running costs and maintenance costs can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a drying furnace according to the present invention.

FIG. 2 is a schematic view showing a chemical change in a furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Drying furnace 2 ... Furnace body W ... Work 7 ... Hot air suction duct 9 ... Hot air blowing duct 14 ... Surface in furnace body 15 ... Inner surface of duct 16 ...・ Water electrolysis promoter 18 ・ ・ ・ Oxygen activator

Claims (4)

[Claims] 1. A drying furnace in which contaminated air containing an evaporated organic solvent is generated by drying a work (W) in a furnace body (2), an exposed surface (14) in the furnace body (2), or On the inner surface (15) of the duct (7, 9, 12) through which air flows in the furnace body (2), a water electrolysis accelerator (16) obtained by kneading pyroelectric material powder with a heat-resistant inorganic adhesive is used. A drying oven characterized by being coated. 2. A drying furnace in which contaminated air containing an evaporated organic solvent is generated by drying a work (W) in a furnace body (2), a surface (14) in the furnace body (2), or An oxygen activator (18) in which ceramic powder containing a radioactive element is kneaded with a heat-resistant inorganic adhesive on the inner surface (15) of a duct (7, 9, 12) through which air in the furnace body (2) flows. A drying oven, characterized by being coated. 3. A drying furnace in which contaminated air containing an evaporating organic solvent is generated by drying a work (W) in a furnace body (2), a surface (14) in the furnace body (2), or A water electrolysis promotion tile made of ceramics obtained by kneading and firing a pyroelectric material powder is attached to the inner surface (15) of a duct (7, 9, 12) through which air flows in the furnace body (2). A drying oven, characterized in that it has been made. 4. A drying furnace in which contaminated air containing an evaporated organic solvent is generated by drying a work (W) in a furnace body (2), an exposed surface (14) in the furnace body (2), or An oxygen-activated tile made of ceramic containing a radioactive element is attached to an inner surface (15) of a duct (7, 9, 12) through which air flows in a furnace body (2). Drying oven.