JPS6127673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention maintains the temperature inside the furnace at a set value by exhausting the furnace while supplying heated gas, and
The present invention relates to a baking drying furnace in which exhaust gas from the furnace body is treated by an exhaust gas treatment device.

This type of baking drying oven is used to bake and dry paint that has been applied to objects by electrodeposition, etc., and contains harmful substances such as evaporated resin and plasticizers that are generated during this process. The exhaust gas is led to an exhaust gas treatment device, treated, and then released into the atmosphere.

As shown in FIG. 1, a large-scale baking drying oven used in a conventional painting line for automobile bodies, etc. has a furnace body 1 in which objects to be coated are carried in and out by a conveyor (not shown). Fans 2 and 3 forming air curtains are disposed at the entrance and exit, respectively, and
The inside of the furnace body 1 is divided into a plurality of areas _A1 to _A4 , and each area Ai (i=1, 2, 3, 4) is provided with a heated gas supply device 4 and an exhaust duct 5, respectively. have

In addition, exhaust ducts 8 are also provided in the hoods 6 and 7 at the entrance and exit of the furnace body 1, and each exhaust duct 5 and 8 is connected to one exhaust gas duct 9 and is connected to a fan 10 installed at the end of the exhaust duct 9. Exhaust gas such as gas containing harmful substances in the furnace body 1 is then sucked and exhausted.

The sucked exhaust gas is once heated through a heat exchanger 11, then reheated by a combustion device 13 supplied with air by a blower 12, and after decomposition and removal of harmful components by a catalyst 14. , is radiated to the atmosphere through the heat exchanger 11. In addition,
An exhaust gas treatment device 15 includes a fan 10, a heat exchanger 11, a combustion device 13, a catalyst 14, and the like.

According to the conventional apparatus described above, the exhaust duct 8 collects harmful gases leaking to the outside from the entrance and exit port of the furnace body 1, which is effective in preserving the environmental hygiene in the vicinity of the drying furnace. The temperature of the exhaust gas collected from the exhaust duct 8 is low because it contains outside air. For example, if the temperature inside the furnace body 1 is maintained at 170℃, the temperature of the exhaust gas from the exhaust duct 8 is 70℃~ 80℃, and each area in the furnace body 1
The exhaust volume at Ai is approximately equal to the air volume supplied into the furnace body 1 by the heated gas supply device 4, for example, 12.5 m ³ /min, but the exhaust gas volume at the entrance and exit is approximately equal to the air volume supplied into the furnace body 1 by the heating gas supply device 4, but the exhaust gas volume at the entrance and exit is the same as the amount of air supplied into the furnace body 1 by the heating gas supply device 4. In order to prevent leakage, for example, 50 m ³ /min is required, so the exhaust gas from the exhaust duct 8 has a low temperature and a large exhaust volume.
Therefore, in the exhaust gas duct 9, the evaporated resin, plasticizer, etc. and high boiling point volatile aqueous substances condense and become tar and adhere to the inner wall of the duct. The disadvantage is that periodic cleaning is required, which is troublesome, as resin adhesion to the catalyst layer can cause a fire or malfunction of the heat exchanger or catalyst layer. It was hot.

The present invention aims to eliminate the drawbacks of the conventional apparatus, and is characterized by supplying the low-temperature exhaust gas at the entrance and exit of the drying furnace to a heated gas supply device that supplies heated gas into the furnace body, and circulating it back to the furnace body. This is what I did.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram showing a baking drying furnace according to the present invention, in which parts corresponding to those in FIG. ing. The heated gas supply device 4 in each area Ai also includes a combustion device 17 to which the gas inside the furnace and fresh air from the blower 16 are supplied, and a fan 18 that blows the heated gas obtained from the combustion device 17 into the furnace body 1. It consists of A purge damper 19 is interposed between the fan 18 and the furnace body 1 to release excess heated gas to the exhaust gas dust 9.

Further, the exhaust gas in the hoods 6 and 7 at the entrance and exit of the furnace body 1 is transferred through exhaust gas ducts 20 and 21 to an air supply passage 22 that connects the furnace body 1 and the intake side of the combustion device 17 in areas A ₁ and A ₄ , for example. The fuel is supplied to the furnace body 1, is reheated by the combustion device 17, and then circulated into the furnace body 1.

In this case, the amount of heated gas supplied to areas A and A of the furnace body 1 increases by the amount of exhaust gas from the hoods 6 and 7, so the exhaust volume of the exhaust duct 5 disposed in these areas A ₁ and A ₄ is The area is selected so that it is larger than that in areas A ₂ and A ₃ .

Next, to explain the effect of the above configuration of the present invention, the low-temperature exhaust gas containing outside air at the entrance and exit of the furnace body is reheated through the combustion device 17 of the heated gas supply device 4 in the vicinity of the area A and A, and the furnace body 1 is reheated. Only the high-temperature exhaust gas inside the furnace body 1 is circulated into the exhaust gas duct 9.
Since the exhaust gas is supplied to the processing device 15 through the exhaust gas duct 9, the exhaust gas temperature in the exhaust gas duct 9 can be prevented from decreasing.

As described above, according to the present invention, the low-temperature exhaust gas at the inlet and outlet of the furnace body is supplied to the heated gas supply device that supplies heated gas into the furnace body, and is reheated by the heated gas supply device and circulated back into the furnace body. The temperature inside the furnace can be easily maintained at the set value, and only the high-temperature exhaust gas inside the furnace can be blown to the exhaust gas treatment equipment through the exhaust gas duct, which reduces the occurrence of dust. , it is possible to significantly reduce the amount of tar adhering to the exhaust gas treatment equipment, etc. compared to conventional equipment, thereby avoiding the risk of fire, preventing malfunction of the exhaust gas treatment equipment, and reducing the number of times of cleaning. It has excellent features such as being able to significantly reduce the amount of water and improving the operating rate of the drying oven.

In the above example, a case was explained in which exhaust gas containing outside air collected from the hoods 6 and 7 was supplied to the suction side of the combustion device 17. The temperature drop may be prevented by setting the temperature of the heated gas from the combustion device high in advance.

Further, the number of regions in the furnace body 1 is not limited to four, but can be selected as appropriate depending on the length of the furnace body 1.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing a conventional baking drying furnace;
The figure is a system diagram showing a baking drying oven according to the present invention. 1...Furnace body, 4...Heating gas supply device, 5, 8
...Exhaust duct, 9...Exhaust gas duct, 15...
Exhaust gas treatment device, 17... Combustion device, 20, 21
...Exhaust gas duct.

Claims (1)

[Claims] 1. In a baking drying furnace that maintains the temperature of the furnace body at a set value by exhausting the furnace body while supplying heated gas, and at the same time treating the exhaust gas from the furnace body with an exhaust gas treatment device, the temperature at the entrance and exit of the furnace body is low. A baking drying furnace characterized in that the exhaust gas is supplied to a heated gas supply device that supplies heated gas into the furnace body, and is circulated into the furnace body.