JPS601547B2 - Hot air drying oven for painting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot air drying oven for coating by heating and drying objects to be coated such as automobile bodies or objects to be surface treated.

BACKGROUND OF THE INVENTION In painting lines for various industrial products, such as automobile bodies, hot air drying ovens are often used that are provided with an air curtain at the closed end where the car bodies are carried into or out of the heating zone.

However, in this type of furnace, even if the air curtain is provided, the heating zone atmosphere is exhausted from the air curtain to the outside of the furnace, and air from outside the furnace flows into the furnace, resulting in a large heat loss. Furthermore, in the closed part, the hot air discharged as described above is cooled in the air curtain part, and the volatile content of the paint contained in the hot air condenses into a crab-like form and adheres to the wall surface of the hot air stove. However, this had the disadvantage that it would fall onto the top surface of the coating, causing defects in the coating film.

The present invention has been made in view of the above points, and its purpose is to provide a hot air drying oven which is extremely suitable for use in automobile painting lines, etc., and which eliminates the above-mentioned drawbacks and difficulties. , its features include a heating zone, a direct-fired combustor that burns the exhaust gas forcibly discharged from the heating zone, an air curtain at a closed part through which objects to be heated are carried in and out of the heating zone, and a a hot air curtain zone provided on the heating zone side adjacent to at least the carry-in closing part side of the curtain; and a pipe system for discharging exhaust gas subjected to combustion treatment by the combustor to the hot air curtain zone via a blower. , a preheat zone provided adjacent to the air curtain on the heating material delivery side and on the opposite side to the heating zone side, and a pipe for discharging the atmosphere in the hot air curtain zone to the preheat zone according to a predischarge amount. There is a hot air drying oven equipped with a system.

Hereinafter, the present invention will be explained based on the drawings.

1 and 2 are diagrams showing one embodiment of the present invention.

First, to explain the configuration, the hot air drying oven according to the present invention has a setting zone 1 connected to a painting booth (not shown), a heating zone 2, and a cooling zone 3 arranged in series as main parts. Circulating air curtain zones 4 and 5 are provided at the opening through which the object to be heated is carried into the zone 2 and the opening through which the object to be heated is carried out from the heating zone 2, respectively.

A hot air curtain zone 6 is provided on at least one surface of the circulating air curtain 4, for example, on the side of the heating zone 2, and a preheat zone 7 is provided on the other surface in connection with the preheat zone 7. A circulating air curtain 8 is provided between the setting zone and the setting zone. As shown in FIG. 1, the heating zone 2 is provided with a hot air supply duct 10 having a large number of closed openings 9 at the lower part of both side walls.

In addition, an intake duct 1 equipped with a large number of closing ports 11 is installed in the ceiling.
2 is provided, and this intake duct 12 is connected to a main combustion chamber 15 containing a direct-fired gas burner unit through a duct 14 equipped with a damper 13.
is connected to the hot air supply duct 0' by a hot air circulation duct 18 equipped with an in-furnace air circulation fan 16 and a damper 17. Note that the main combustion chamber 15 includes a flow control valve 1.
9, a fuel gas pipe 20 with a damper 21, a pipe 22 with a damper 21, a secondary heat exchanger 23, and a supply air fan (
A combustion air supply duct 24 equipped with a combustion air supply (not shown) is connected to the combustion air supply duct 24. In addition, there is another exhaust opening □25 in the ceiling of heating zone 2.
This opening □ 25 is provided with an exhaust duct 29 equipped with a damper 26 , a blower 27 and a secondary heat exchanger 28 .
Three auxiliary combustion chambers with built-in direct-fired (or catalytic direct-fired) gas burner units are connected.

Note that a fuel gas pipe 32 equipped with a flow rate control valve 31 is connected to this sub-combustion chamber 30. The sub-combustion chamber 30 is
It is connected to the hot air curtain zone 6 via a combustion treatment exhaust duct 35 with a primary heat exchanger 28, a secondary heat exchanger 23, a blower 33 and a damper 34, and by a duct 73 with a damper 72. It is connected to the combustion air supply duct 24. hot ware curtain thorn 6
As shown in FIG. 2, a hot air duct 37 is provided with a nozzle 36 opened in the form of a vertical slot on both side walls, and this hot air duct 37 is connected to a duct 39 equipped with a damper 38. It is connected to the twisting treatment exhaust duct 35 by.

An exhaust chamber 41 with a slot-shaped opening 40 is provided in the ceiling of the Hot Ware Car Tenson 6, and this exhaust chamber 41 is connected to a duct 43 with a fan 42. The duct 43 is further connected to the atmosphere by an exhaust pipe 45 provided with a damper 44 and connected to the preheat zone 7 by a duct 47 provided with a damper 46 . A hot air supply duct 49 having a discharge outlet 48 at its lower part is provided in the preheat zone, and this air supply duct 49 is connected to the duct 47 .

In addition, an exhaust gate 50 is installed on the ceiling of the preheat zone 7.
This closed end is connected to an exhaust pipe 53 with a damper 51 and a fan 52, suitable for the atmosphere. Throat-shaped outlet ports 60a, 61a, 62a and suction closure S of circulating air curtain saws 4, 5, 8
ob, 61b, 62b are circulation ducts 57, 58, each equipped with circulation fans 54, 55, 56, respectively.
It is connected to the outlet side and suction side of 59.

The cooling zone 3 includes an air supply duct 64 equipped with an air supply fan 63 and an exhaust duct 6 equipped with an exhaust fan 65.
6 is connected.

In addition, as shown in FIG.
A cart 71 for transporting the object 70 is configured to run on the surface of the substrate 9 .

Next, the effect will be explained. By adjusting the damper 13, a required amount of atmosphere in the heating zone 2 is taken in from the heating zone 2 through the open row 1 and the intake duct 12, and is sent to the main combustion chamber 15 through the duct 14 for heating. That is, in this main combustion chamber 15, fuel gas, such as city gas, is supplied from two combustion gas pipes while controlling the flow rate with a flow rate control valve 19, and on the other hand, fuel gas, such as city gas, is supplied from the combustion air supply duct 24 while being adjusted with a damper 21. After the air in the atmosphere is subheated by the secondary heat exchanger 23, it is supplied to the main combustion chamber 15 through the duct 22 and combusted by the direct gas burner, and the atmosphere is heated by this combustion and the damper is heated. Hot air is sent through the hot air duct 01 by the furnace air circulation fan 16 through the duct 18 while adjusting the air volume with the airflow duct 17, and is supplied to the heating zone 2 through the closing port 9, thereby raising the atmospheric temperature in the heating zone 2 to, for example, about 1600C. Keep it. On the other hand, when the atmosphere in the heating zone 2 is circulated as described above, volatile components from the coating film of the object to be coated and carbon monoxide gas harmful products generated during the combustion are removed from the atmosphere. Since it is necessary to remove a part of the atmosphere in the heating zone 2, a part of the atmosphere in the heating zone 2 is used as exhaust air and is sent from the exhaust opening □ 25 to the primary heat exchanger 28 with the blower 27 while adjusting the exhaust air volume with the damper 26 for subheating. After preheating, the exhaust gas is sent through the duct 29 to three auxiliary combustion chambers and heated to burn the volatile components contained in the exhaust gas, that is, hydrocarbon solvents, resin vapors (approximately 80 kg), and carbon monoxide. harmless C0
It is oxidized and decomposed on days 2 and 20.

That is, in this auxiliary combustion chamber 30', fuel gas, for example, city gas, is supplied through the fuel gas pipe 32 while controlling the flow rate with the flow rate control valve 31, while the damper 7
2, atmospheric air is preheated from the combustion air supply duct 24 by the secondary heat exchanger 23, and then supplied to the auxiliary combustion chamber 301 through the duct 73 to generate a direct-fired gas burner unit (or a catalyst). The combustion exhaust gas is combusted together with the exhaust gas from the heating zone 2 containing the solvent etc. using the attached direct-fired gas burner unit), and the combustion exhaust gas is transferred to the primary heat exchanger (the temperature of the combustion exhaust gas is, for example, about 30,000 yen in front of the primary heat exchanger).
After heat exchange, it passes through a secondary heat exchanger (e.g., about 20,000 liters after the secondary heat exchanger) 28 and a combustion treatment exhaust duct 35 by a blower 33 while adjusting a damper 34 to a hot air curtain zone 6. Then, hot air at a temperature higher than that of the heating zone 2 (for example, a temperature of about 190q
o). In the hot air curtain zone 6, the hot air whose air volume is adjusted by the duct 38 and is supplied to the hot air blowing duct 37 by the duct 39 is ejected from the nozzle 36 closed in the shape of a vertical slot to form a hot air curtain.

Exhaust from the hot air curtain saw 6 passes through an exhaust chamber 41 through a slot-shaped closure 40 and then to a fan 42.
The hot air is discharged from the duct 43 by the damper 46, and the hot air (for example, about 9000 ℃) is sent to the hot air duct 49 in the preheat zone 7 through the duct 47 while the air volume is adjusted by the damper 46.
A part of the air is discharged into the atmosphere through a duct 45 while the air volume is adjusted by a damper 44. In the preheat zone 7, hot air is discharged from the discharge closing port 48 to maintain the indoor temperature at, for example, about 5,000 ℃, and the hot air is transferred from the exhaust closing port 50 to the exhaust pipe 53 by the fan 52 while adjusting the air volume with the damper 51. (e.g. about 3000) and then released into the atmosphere.

In the cooling zone 3, the air introduced through the duct 64 is supplied to the cooling zone 3 by the fan 63, while the exhaust air is discharged into the atmosphere by the fan 65 through the duct 66.

In addition, in the circulation air curtain zones 4, 5, 8, the ducts 57, 58, 5 are connected by the fans 54, 55, 56.
Air is circulated through the slot-shaped outlet closure 60
a,61a? 62a to form an air curtain. Under these conditions, the coating material 70 on the trolley 71 that has been painted in a coating booth (not shown) passes through the setting zone 1 (in the direction of the arrow in FIG. Drying and baking of the coating film are completed by passing through zone 2, cooling zone 3, etc.

Note that when an organic solvent-based paint is sprayed in a paint booth (not shown), the organic solvent evaporates from the paint film in the preheat zone 7, but is considerably diluted by the exhaust gas introduced into the preheat zone 7. Ru.

However, the exhaust air from the preheat zone 7 is further filtered by a filter device that combines a glass fiber mat filter (for example, Roll-O-Matic type V-J, manufactured by American Air Filter Co., Ltd.) and an activated carbon adsorption filter, or by other means. It is desirable that the solvent be passed through a type of solvent removal device to reduce the solvent concentration to about 2 mm or less. The preheat zone in the examples is preferably provided when drying a coated object coated with a paint containing a low organic solvent content, but for example, it is preferable to provide a preheat zone when drying a coated object coated with a paint containing a low organic solvent content. It can be omitted in cases such as when drying a coating. As described above, in the present invention, a hot air drying furnace for painting is provided with a heating zone, a direct-fired combustor that burns exhaust gas forcibly discharged from the heating zone, and an object to be heated in the heating zone. a hot air curtain zone provided on the heating zone side at least adjacent to the loading/unloading opening side of the air curtain; a pipe system that discharges air through a blower, and a pipe system that is adjacent to the air curtain on the side where the heated object is carried in and discharges the atmosphere in the heating hot air curtain zone to the preheat zone according to the amount of air discharged. It is composed of

Under this configuration, the exhaust gas forcibly discharged from the heating zone is combusted by a direct-fired combustor, and the combusted exhaust gas is discharged through the pipe system to a zone adjacent to at least one side of the air curtain. The temperature of this atmosphere is higher than the atmosphere temperature of the heating zone (so-called hot air temperature) due to the combustion process, so the atmosphere of the heating zone (
When the so-called hot air) comes into contact with the atmosphere in the adjacent zone, the atmosphere in the heating zone (so-called hot air) acts to expand at this contact area,
The atmosphere in the heating zone (so-called hot air) flowing out of the system through this adjacent zone is regulated to a very small amount.
As the amount of air flowing into the heating zone from the outside decreases in accordance with the decrease in the outflow amount, it is possible to reduce the heat loss at the closed part of the heating zone, and as described above, the amount of air flowing into the heating zone from outside the system decreases. Since the atmosphere (so-called hot air) is regulated to a very small amount, by cooling this atmosphere, the amount of volatile matter in the paint that is contained in the atmosphere condenses and becomes crab-like can also be reduced. This effect is achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a hot air drying oven for coating according to the present invention, and FIG. 2 is a sectional view taken along the Rollo line in FIG. 1. 1... Setting zone, 2... Heating zone, 3... Cooling zone, 4, 5, 8... Circulating air curtain zone, 6... Hot air curtain zone, 7... Preheating zone, 15... Main combustion chamber, 16...Furnace air circulation fan, 18...Hot air circulation duct, 23, 28...
- Heat exchanger, 30... Sub-combustion chamber, 35... Combustion processing exhaust duct. Figure 1 Figure 2

Claims (1)

[Claims] 1. A heating zone, a direct-fired combustor that burns exhaust gas forcibly discharged from the heating zone, an air curtain at an opening for carrying objects to be heated into and out of the heating zone, and at least the carrying-in opening of the air curtain. a hot air curtain zone provided on the heating zone side adjacent to the side; a pipe system for discharging exhaust gas subjected to combustion treatment by the combustor to the hot air curtain zone via a blower; and a heating object delivery side. a preheat zone provided adjacent to the air curtain on a side opposite to the heating zone side, and a pipe system for discharging the atmosphere in the hot air curtain zone to the preheat zone according to the discharge amount. A hot air drying oven for painting.