JPH0243034Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an indirect convection type paint drying oven suitable for uniformly baking and curing a paint film formed on the surface of an object to be dried.

[Conventional technology]

Conventionally, in paint drying furnaces, resin products, such as urethane resin bumpers and polypropylene resin bumpers, are continuously carried in to be dried using a conveyor or other conveyance device, and the paint film is baked and cured.
An indirect convection type paint drying oven as shown in the schematic front sectional view of FIG. 5 is used.

In FIG. 5, reference numeral 41 denotes a furnace body formed in the shape of a tunnel, and a suction duct 42 is provided at the center of the upper part of the furnace body 41.
Blowout ducts 43a and 43b are provided on both sides of the lower part of the air conditioner. Suction ports 42a and 42b are formed on the lower surface of the suction duct 42,
Air outlets 43c and 43d are formed at the inner corner surfaces of the air outlet ducts 43a and 43b.

Further, a circulation fan 44 is provided in the middle of the blow-off ducts 43a and 43b, and one end of a first circulation duct 46 communicating with a heat exchanger 45 is connected, and the other end of this first circulation duct 46 is connected to a suction fan 44. It is connected to the duct 42.

Further, a second circulation duct 47 forming a loop is connected to the heat exchanger 45, and an exhaust duct 48a is provided in the middle of the second circulation duct 47. A combustion burner 49 and a circulation fan 50a are provided in the upstream part of the second circulation duct 47.
Opening/closing dampers 51a and 51b are provided in the circulation duct 47 and the exhaust duct 48a. Further, an air supply duct 48b equipped with a supply fan 50b is connected to the combustion burner 49.
9 to supply combustion air.

Further, a conveyor 52 is laid in the center of the lower part of the furnace body 41, and a plurality of carts 53 are provided on the conveyor 52 for placing and conveying the material to be dried W.

Then, when baking and curing the coating film on the material to be dried W, fuel and combustion air are supplied to the combustion burner 49 to combust the fuel. Next, the high temperature air from the combustion burner 49 is circulated to the second circulation duct 47 by the circulation fan 50a, and heat exchanged with the air circulating in the first circulation duct 46 by the heat exchanger 45. The heat-exchanged high-temperature air is then transferred to a blow-off duct 43 provided at the lower part of the furnace body 41.
Send from the air outlets 43c, 43d of a, 43b, suction ports 42a, 42b of the suction duct 42
The air is sucked in from the air and circulated within the first circulation duct 46. As a result, the inside of the furnace body 1 is maintained at a constant temperature, and the coating film is baked and hardened while the material to be dried W on the cart 53 is transported by the conveyor 52.

[Problem that the invention attempts to solve]

However, in such an indirect convection type paint drying oven, when baking and curing the paint film formed on the surface of the object W to be dried, chlorine-based compounds scattered during drying on the object W to be dried are removed. Since the outside air in the factory containing a small amount is supplied to the combustion burner 49 from the air supply duct 48b by the supply fan 50b, the chlorine compounds contained in the outside air react with the direct flame of the combustion burner 49. Acidic substances such as hydrogen chloride that accelerate corrosion are generated. This acidic substance is gradually concentrated as it circulates with the high temperature air in the second circulation duct, and some exhaust gas is transferred to the exhaust duct 4.
When the air is exhausted from the exhaust duct 8a, it may be cooled by the ambient temperature in the factory and may condense in the exhaust duct 48a. For this reason, there is a problem that the exhaust duct 48a is damaged by the dew-condensed acidic substance and corroded early.

Therefore, this invention was made to solve the above-mentioned problems, and by providing a supply means for introducing outside air in the middle of the exhaust duct connected to the hot air circulation duct, it is possible to introduce outside air into the exhaust gas. The purpose is to reduce the concentration of acidic substances contained and prevent corrosion of exhaust ducts.

[Means for solving problems]

That is, in the indirect convection type paint drying oven according to the present invention, the heat exchanger is connected to a hot air circulation duct forming a loop and an in-furnace circulation duct that is open at both ends and communicates with a suction duct and an outlet duct in the furnace body. This in-furnace circulation duct is equipped with a circulation fan for circulating high-temperature air. In addition, the hot air circulation duct is equipped with a combustion burner for burning fuel to obtain high-temperature air and a circulation fan for circulating the high-temperature air obtained by the combustion burner.The combustion burner is equipped with an air supply duct. connected to supply combustion air to the combustion burner.

Further, an exhaust duct is connected to the hot air circulation duct, and exhaust gas corresponding to the amount of combustion air supplied from the supply air duct to the hot air circulation duct is discharged to the outside. Further, a supply means for introducing outside air is provided in the middle of the exhaust duct to reduce the concentration of acidic substances contained in the exhaust gas discharged from the exhaust duct.

[Effect]

In such an indirect convection type paint drying furnace, when baking and curing the paint film of the object to be dried, fuel and combustion air are supplied to the combustion burner to combust the fuel. Next, the heated air obtained by the combustion burner is circulated through the hot air circulation duct by a circulation fan,
A heat exchanger exchanges heat with the air circulating in the furnace circulation duct.

The heat-exchanged high-temperature air is sent through the blow-off duct provided inside the furnace body, sucked in through the suction duct, and the high-temperature air is passed through the furnace circulation duct.
Circulate sequentially through the blow-off duct, the furnace body, and the suction duct. As a result, the inside of the furnace is maintained at a constant temperature, and the paint film is baked and hardened while the material to be dried is transferred.

On the other hand, the heated air circulating in the hot air circulation duct is discharged to the outside from the exhaust duct as exhaust gas in an amount equal to the amount of combustion air supplied from the supply air duct to the combustion burner. At that time, a large amount of outside air is supplied from the supply means provided in the middle of the exhaust duct, and the concentration of acidic substances in the exhaust gas released from the exhaust duct to the outside is diluted, and the exhaust gas is also diluted. released to the outside.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the indirect convection type paint drying furnace according to the present invention will be described in detail based on the drawings.

Figure 1 is a schematic side view of the indirect convection type paint drying oven according to the present invention, Figure 2 is a sectional view taken along the - line in Figure 1, and Figure 3 is an enlarged view of the area A in Figure 1. It shows a cross-sectional view.

In FIGS. 1 and 2, reference numeral 1 denotes a tunnel-shaped furnace body with both ends open, one of which serves as an inlet 1a and the other as an outlet 1b. A suction duct 2 is provided in the center of the ceiling of the furnace body 1 in the longitudinal direction, and a plurality of suction ports 2a are formed in the lower surface thereof in the longitudinal direction. Further, on both sides of the bottom of the furnace body 1, there are blow-off ducts 3a extending in the longitudinal direction.
3b, and a plurality of air outlets 4a, 4b are formed at the inner corners thereof, respectively.

In addition, a conveyor 5 is laid in the center of the bottom of the furnace body 1 in the longitudinal direction, and on the top surface of the conveyor 5, the material to be dried W on which a painted film such as a bumper made of urethane resin or a bumper made of polypropylene resin is formed is placed. A plurality of carts 6 for placing and transporting the objects are provided at intervals. Furthermore, the periphery of the conveyor 5 is covered with a gate-shaped cover 7 to protect it from the temperature atmosphere of the furnace body 1.

Further, an in-furnace circulation duct 8 is arranged outside the furnace body 1, one end of which is connected to the suction duct 2 provided on the ceiling of the furnace body 1, and the other end connected to the bottom of the furnace body 1. It is connected to two blowout ducts 3a and 3b provided in the. The furnace circulation duct 8 is provided with a heat exchanger 9 and a circulation fan 10 from the downstream side, and when the circulation fan 10 operates, air in the furnace body 1 is sucked into the furnace circulation duct 2 and then into the furnace circulation duct. 8, the heat exchanger 9, the blow-off duct 3, and the inside of the furnace body 1.

Further, a hot air circulation duct 11 forming a loop is connected to the heat exchanger 9, and a combustion burner 12 that burns fuel to generate heated air and a heated air generated by the combustion burner 12 are connected to the heat exchanger 9. A circulation fan 13 for circulating the water is provided. Further, an air supply duct 14 for supplying combustion air is connected to the combustion burner 12, and a supply fan 15 is provided at the tip of the air supply duct 14. A fuel supply pipe (not shown) is connected to this combustion burner 12.

In addition, a combustion burner 12 is provided in the hot air circulation duct 11.
An exhaust duct 16 is connected to the upstream side of the exhaust duct 16, the tip of which projects outward from the roof 18 of the factory. Furthermore, as shown in FIG. 3, this exhaust duct 16 is edged in the middle, and an air introduction member 17 formed in a hat shape and open at the bottom is fixed to the upper part. And exhaust duct 16
When the heated air circulating in the hot air circulation duct 11 is discharged as exhaust gas, a large amount of outside air flows from the open part of the lower part of the air introduction member 17 into the arrow B due to the suction action generated in the hot air circulation duct 11. It is designed to be supplied in the direction of

In the indirect convection type paint drying furnace configured as described above, when baking and curing the paint film formed on the surface of the object W to be dried, the circulation fan 10 of the furnace circulation duct 8 and the hot air circulation duct 11 circulation fan 13 is operated to circulate the air inside the furnace body 1 to the furnace circulation duct 8, the heat exchanger 9, and the blowout ducts 3a, 3.
b. Circulate sequentially within the furnace body 1 and the suction duct 2.

At the same time, the supply fan 1 to the combustion burner 12
5 to the air supply duct 14 to supply combustion air, and also to supply fuel for combustion.
Then, the heated air produced by the combustion burner 12 is circulated to the hot air circulation duct 11 by the circulation fan 13, and the heated air is circulated to the hot air circulation duct 11 by the heat exchanger 12.
The heat of the heated air on the side is exchanged with the air circulating in the furnace circulation duct 8 side.

Next, the heat-exchanged high-temperature air is transferred to blow-off ducts 3a and 3b disposed on both sides of the bottom of the furnace body 1.
It is also supplied into the furnace body 1 from the blow-off ports 4a and 4b. Then, a part of the high temperature air supplied into the furnace body 1 is sucked into the suction port 2 of the suction duct 2.
It is sucked in from a and returned to the furnace circulation duct 8 for sequential circulation.

As a result, the inside of the furnace body 1 is at a predetermined temperature of 130
The trolley 6 is maintained at an ambient temperature of ℃ to 140℃.
While the upper material to be dried W is being transported by the conveyor 5, it is exposed to the temperature inside the furnace body 1, and the paint film is baked and
hardened.

On the other hand, the heated air circulating in the hot air circulation duct 11 is discharged to the outside from the exhaust duct 16 as exhaust gas by the supply amount of combustion air supplied from the air supply duct 14 to the combustion burner 12 by the supply fan 15. be done. At this time, due to the suction action generated within the hot air circulation duct 11, a large amount of air is supplied from the lower opening of the air introduction member 17 provided in the middle of the exhaust duct 16, and from the exhaust duct 16 to the outside. The concentration of acidic substances in the discharged exhaust gas is reduced, and the exhaust gas is also diluted and discharged to the outside.

As a result, even if the acidic substances in the exhaust gas are cooled at the ambient temperature in the factory and condensed, corrosion of the exhaust duct 16 is prevented because the concentration of the acidic substances is reduced. In addition, the exhaust duct 16
Exhaust gas discharged to the outside is also discharged in a diluted state, thereby preventing it from polluting the atmosphere.

In this embodiment, the air introduction member 17 formed in the shape of a hat is used as a supply means for introducing outside air provided in the middle of the exhaust duct 16. However, according to the present invention, the air introduction member 17 is The present invention is not limited to this, and for example, as shown in FIG. 4, a supply pipe 19 bent upward may be inserted in the middle of the exhaust duct 16, and a supply fan 20 may be provided at the other end. effect can be obtained.

[Effect of idea]

As explained above, in the indirect convection type paint drying oven according to the present invention, since the supply means for introducing outside air is provided in the middle of the exhaust duct connected to the hot air circulation duct, the exhaust gas discharged from the exhaust duct is Since the concentration of acidic substances inside can be reduced, corrosion of the exhaust duct can be prevented.

Furthermore, in the indirect convection type paint drying oven according to the present invention, the exhaust gas discharged to the outside from the exhaust duct is also diluted by the introduced outside air.
It has the effect of preventing air pollution.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of an indirect convection type paint drying oven according to the present invention. FIG. 2 is a front view taken along the - line in FIG. 1. FIG. 3 is an enlarged sectional view of the area A in FIG. 1. FIG. 4 is a schematic sectional view showing another embodiment of the supply means according to the present invention. FIG. 5 is a sectional view of a conventional indirect convection type paint drying oven as viewed from the front. 1...Furnace body, 2...Suction duct, 3a, 3b
...Blowout duct, 8...Furnace circulation duct, 9...
... Heat exchanger, 10 ... Circulation fan, 11 ... Hot air circulation duct, 12 ... Combustion burner, 13 ... Circulation fan, 14 ... Air supply duct, 16 ... Exhaust duct, 17 ... Air introduction member.

Claims (1)

[Scope of utility model registration request] The heat exchanger is connected to a hot air circulation duct forming a loop and an in-furnace circulation duct which is open at both ends and which communicates with an inlet duct and an outlet duct in the furnace body, a circulation fan is provided in this in-furnace circulation duct, and the hot air circulation duct is connected to the heat exchanger. A combustion burner and a circulation fan are provided in the combustion burner, and a supply air duct for supplying combustion air to the combustion burner is connected to the combustion burner, and further, combustion air is supplied from the supply air duct to the hot air circulation duct. An indirect convection type paint drying oven characterized by being connected to an exhaust duct for discharging a quantity of air to the outside, and provided with a supply means for introducing outside air in the middle of the exhaust duct.