JPH037882A - Method of air supply and discharge for painted surface baking furnace - Google Patents

Abstract

PURPOSE:To improve the effect of scavenging gummy substances in the baking range and ministurize the blower and the deodorizing device by forming a flow of air in the furnace by supplying preheated air to the drying range and discharging exhaust air from the baking range, and controlling the supply of preheated air by analyzing the combustible components of exhaust gas so that the air in the furnace may remain below its explosion limit. CONSTITUTION:Preheated air which has been preheated by a heat exchanger 7 in the duct 4 is supplied to the drying range A1 through the duct 9 by means of a blower 8. Part of the air in said range in the furnace is sucked by a circulation fan F1 to be circulated to the nozzle header 2a, and the remainder enters into the drying range A2. Part of the air in the drying range A2 is similarly sucked by a circulation fan F2 to be supplied to the nozzle header 2b, and the remainder enters the baking range B1. Such is also true with the baking ranges B1, B2. The exhaust gas is discharged from the baking range B2 through the duct 4 by means of an exhaust fan 3. A solvent concentration measuring instrument is disposed on the upstream side of the baking range B2 to operate a valve 13 to control the supply of preheated air so that the solvent concentration in the exhaust gas may remain below the explosion limit.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for supplying and exhausting a paint baking furnace.

(Prior art) A paint baking oven generally consists of a drying zone and a baking zone. As shown in Figure 3, in the drying zone, the solvent, which is a combustible component in the paint, evaporates, while in the baking zone, the tar evaporates. The component polymer resin evaporates.

The former causes an explosion when its content exceeds a predetermined amount, and the latter solidifies in the low-temperature part of the baking zone and drips onto the treated material, causing staining.

Therefore, conventionally, for example, JP-A-60-54764
As shown in the publication, preheated air is supplied to each zone, furnace air is exhausted to each zone, and in each zone of the drying zone, the concentration of evaporated solvent in the exhaust gas is detected, and the furnace air in that zone is Air is supplied so that it is below the explosion limit, and preheated air for purging is supplied to each zone of the seizure zone as a countermeasure against tar.

Furthermore, the exhaust gas from each of the zones is incinerated to remove combustible components in the exhaust gas by a deodorizing device installed in the collective exhaust duct, and then discharged into the chimney.

(Problem to be Solved by the Invention) By the way, the above-mentioned countermeasure against tar can be more completely achieved by supplying a large amount of preheated air to the baking zone, but this will increase the amount of exhaust gas. Not only does this require the equipment and exhaust fan to be larger, but it also results in a loss of thermal energy.

In addition, mixing of furnace air occurs between the drying zone and the baking zone, and in particular, if the furnace air from the baking zone flows into the drying zone, the temperature of this zone is lower than that of the baking zone, so as mentioned above, resin may be formed on the treated material. There were problems such as dripping and causing stains.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air supply/exhaust method for a paint baking furnace that can solve the above-mentioned conventional problems.

(Means for Solving the Problems) In order to achieve the above object, the present invention supplies preheated air to the drying zone of a paint baking furnace, while exhausting furnace air from the baking zone to create a starting zone in the furnace. A method for supplying and exhausting a paint baking furnace, characterized in that a flow of furnace air is formed from the air to the final zone, and the supply of the preheated air is controlled depending on the amount of combustible components in the exhaust gas, so that the furnace air is below the explosion limit. It is.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, and 1 is a paint baking oven, which is composed of drying zones A, , A and baking zones Bl+B, and each zone is filled with paint. Nozzle headers 2a to 2d are provided across the conveyance path for the applied treatment material W. Exhaust gas from the paint baking furnace 1 is sent from the baking zone B, which is the final zone, to a known deodorizing device 5 via a duct 4 by an exhaust fan 3, where combustible components in the exhaust gas are incinerated by a burner (not shown). Then, it is deodorized and discharged to the outside from the chimney 6.

On the other hand, preheated air preheated by the heat exchanger 7 provided in the duct 4 by the blower 8 is supplied to the nozzle header 2a of the drying zone A1 by the tact 9. The relevant band A
A part of the furnace air is sucked by the circulation fan F and circulated to the nozzle header 2a, and the remaining part flows into the downstream drying zone A.

Similarly to the above, the furnace air in the drying zone A is sucked by the circulation fan F and supplied to the nozzle header 2b in the zone, and also flows into the burning zone B+.

The same applies to the burn-in zones B, , B, and so on.

In this embodiment, except for the final zone B, a part of the circulating reactor air in the zone is supplied to the circulating reactor air in the downstream zone,
It makes the furnace air flow more reliable, but it is not necessary.

Furnace air from the baking furnace 1 flows from the drying zone A1, which is the starting zone, to the baking zone B, which is the final zone.

In addition, each zone A, ,A, ,B, ,B, is heated to 250°C1 in the drying zone A, ,A, by a heater provided in each zone.
280°C in baking zone B1 300°C in baking zone B2
The temperature is controlled at °C.

Further, a pressure detector 10 is provided in the seizure zone B, and a detection signal of the pressure detector 10 is used to detect the duct 4.
The on-off valve 11 provided on the upstream side of the deodorizing device 5 is opened and closed to perform minute control so that the inside of the paint baking furnace l does not become negative pressure. Note that the pressure detector 10 and the on-off valve 1 are not necessarily necessary because the amount of preheated air supplied into the furnace 1 and the amount of exhaust gas exhausted from the furnace are almost equal.

Furthermore, a solvent concentration measuring device 12 is provided in the duct 4 upstream of the deodorizing device 5, and the duct 9 is arranged so that the solvent concentration in the exhaust gas in the duct 4 is below the explosion limit.
The amount of preheated air supplied to the paint baking furnace 1 is controlled by opening and closing an on-off valve 13 provided in the paint baking furnace 1.

Next, the operation of the paint baking furnace constructed as described above will be explained.

Now, the treated material W whose surface has been coated with paint is placed in the paint baking furnace 1.
When the treatment material W is charged into the furnace 1, it is heated by hot air from each header 2a to 2d while passing through the furnace 1, and the paint is dried and baked and extracted outside the furnace.

On the other hand, the preheated air supplied to the nozzle header 2a of the drying zone A is exhausted by the exhaust fan 3 through the drying zone A1, the baking zones B, .

That is, in the conventional example, preheated air was supplied to each zone of the paint baking furnace and the furnace air was exhausted from that zone, but in this embodiment, for example, the conventional drying zone A
The total amount of preheated air previously supplied to drying zone A is supplied only to drying zone A to form a furnace air flow in the furnace from starting zone A to final zone B. , which exhausts furnace air from the burning zone B, where tar components are generated.
, B2 are purged with the furnace air.

In addition, in the above embodiment, the starting end zone A1 of the paint baking furnace 1
Supply preheated air only to the final zone B.

However, as shown in Fig. 2, a part of the supplied preheated air is introduced into other zones of the drying zone through the bypass duct 9a, and a part of the supplied preheated air is introduced into other zones of the drying zone through the bypass duct 4a. A part of the furnace air may be exhausted by

(Effects of the Invention) As is clear from the above explanation, according to the method of the present invention, a sufficient amount of preheated air is supplied to the drying zone so that the solvent concentration in the furnace air becomes below the explosion limit, and from the burning zone to the furnace. To exhaust air,
A large amount of furnace air is supplied to the burning zone, and the effect of scavenging tar components in the burning zone can be made greater than before. Furthermore, since the furnace air flows from the starting end zone to the final zone, the furnace air containing tar components from the baking zone does not flow into the drying zone and stain the treated material.

Furthermore, the amount of preheated air supplied to the furnace (furnace air exhausted from the furnace) is sufficient to ensure that the furnace air is below the explosion limit, which reduces the size of the blower and deodorizing device and reduces equipment costs. be able to.

Note that if the same amount of preheated air is supplied to the dry zone as was supplied to each zone in the past, it is possible to achieve more complete measures against tar without increasing the size of the blower or deodorizing device.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a paint baking furnace according to a first embodiment of the present invention, Fig. 2 is a schematic diagram of a paint baking furnace according to a second embodiment, and Fig. 3 is a schematic diagram of a paint baking furnace according to a second embodiment of the present invention. It is a graph showing processing material temperature, solvent, and evaporation state of polymer resin. DESCRIPTION OF SYMBOLS 1... Baking furnace, 2a-2d... Header, 3... Blower, 4... Duct, 5... Deodorizing device, 7... Heat exchanger, 8... Blower, 9... ...Duct, 12...
Solvent concentration measuring device, 13... Opening/closing valve, A,, A,...
Drying zone, B, , B, . . . baking zone. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) While supplying preheated air to the drying zone of the paint baking furnace,
Furnace air is exhausted from the seizure zone to form a flow of furnace air from the starting zone to the final zone in the furnace, and the supply of the preheating air is controlled by the amount of combustible components in the exhaust gas to maintain the furnace air to the explosive limit. A method for supplying and exhausting a paint baking furnace, characterized by the following: