JPH0741201B2 - Control method for continuous drying and baking equipment for paint - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method in an apparatus for performing continuous dry baking on a coating material applied to a treatment material such as a metal strip, and particularly in a dry baking oven in a dry baking apparatus using hot air. The present invention relates to a method of controlling hot air introduced into the.

As a dry baking device that heat-cures paints and drains and drys, various types of hot air circulation furnaces, infrared furnaces, etc. are known, but in mass production lines such as dry baking of coated steel sheets, From the viewpoint of energy saving, the hot air circulation type is often used.

Typical examples of the conventional hot-air circulation type continuous drying / baking apparatus are shown in, for example, JP-A-57-50576 and JP-A-57-95585, the basic structure of which is shown in FIG. Shown in.

In FIG. 2, a dry baking oven 1 is a treatment material (for example, a metal strip) coated with a coating material by a roll coater 2.
3 is continuously passed from one opening (that is, the inlet) to the other opening (that is, the outlet), and the dry baking furnace 1 has a plurality of zones 1A to 1N inside. It is divided into. Exhaust gas from the dry baking furnace 1, that is, furnace exhaust gas containing solvent vapor, is exhaust gas pipe 5
Is sucked and exhausted from the dry baking furnace 1 by the blower 6 via the blower 6, and the furnace exhaust gas passes through the damper 7 and the gas flow meter 8 as exhaust gas flow rate detecting means for the incinerator, and the first heat exchanger 9 to the incinerator (combustion device) 10. Will be introduced to. In this incinerator 10, combustion air and a fuel 12 from a second heat exchanger 11 which will be described later are supplied to a burner 13 to incinerate solvent vapor contained in the furnace exhaust gas from the dry baking furnace 1. To do. Then, part of the incineration exhaust gas of the incinerator 10 is part of the main pipe 14a of the return gas pipe 14.
And each zone 1A to 1N of the dry baking furnace 1 through the branch pipe 14b.
The circulation blower 15 installed in the circulation path 20 of each zone
It is introduced to 1A-1N and used as a heat source for dry baking of paint.

On the other hand, the rest of the incineration exhaust gas of the incinerator 10 passes through the discharge path 16 and the first heat exchanger 9 and the second heat exchanger 11, and is finally discharged from the chimney 17 to the atmosphere. In the first heat exchanger 9, the furnace exhaust gas of the dry baking furnace 1 and the incinerator exhaust gas of the incinerator 10 exchange heat with each other, and the furnace exhaust gas of the dry baking furnace 1 is heated. The second heat exchanger
In 11, the combustion air taken from the outside by the blower 18 and the incineration exhaust gas of the incinerator 10 are heat-exchanged, the temperature of the combustion air is raised, and the combustion air is burned by the burner 13 of the incinerator 10 as described above. Given.

The circulation blower is provided in each circulation path 20 including the circulation blower 15 corresponding to each zone 1A to 1N of the dry baking furnace 1.
A cooling air intake passage 21 for taking in cooling air from the outside is connected to the upstream side of 15, and each cooling air intake passage 21 is provided with a damper 22 for controlling the amount of cooling air taken in. Further, each branch pipe 14B of the return gas pipe 14 for guiding a part of the incineration exhaust gas from the incinerator 10 to the dry baking furnace 1 is provided with a damper 24 for controlling the intake amount of the incineration exhaust gas to each zone. In addition, a temperature sensor 25 is provided on the outlet side of each circulation blower 15 in each circulation passage 20.

Here, the temperature control of the dry baking oven 1 is performed as follows. That is, each zone 1A in each temperature sensor 25
Based on the temperature measurement result of ~ 1N, temperature instruction controller (TIC) 26
By controlling the opening / closing of the damper 22 for controlling the intake amount of cooling air and the damper 24 for controlling the introduction amount of incineration exhaust gas through the, to change the intake mixing ratio of the cooling air at low temperature around room temperature to the high temperature incineration exhaust gas. Thus, the temperature control of each zone 1A to 1N is performed.

The discharge amount of the furnace exhaust gas guided from the dry baking furnace 1 to the incinerator 10 through the exhaust gas discharge pipe 5 is the condition of the processing material 3, that is, the amount of solvent in the applied coating material, the line speed of the processing material 3 or the processing material 3. The damper 7 is controlled by the flow rate instruction controller (FIC) 27 according to the flow rate value detected by the gas flow meter 8 as the exhaust gas flow rate detecting means for the incinerator. In addition, the internal pressure of the furnace is controlled to be a slight negative pressure to prevent the exhaust of the exhaust gas from the furnace.

Problems to be Solved by the Invention The conventional continuous dry baking apparatus as shown in FIG. 2 has the following drawbacks.

That is, although the furnace exhaust gas amount of the dry baking furnace 1 discharged through the exhaust gas pipe 5 is controlled as described above, the total amount of the incineration exhaust gas as a heat source and the cooling air introduced into the dry baking furnace 1 is particularly large. It was uncontrolled and therefore its total gas uptake was left to success. As described above, since the internal pressure of the dry baking furnace 1 is controlled to be a slight negative pressure in normal times, a small amount of air always enters from the furnace inlet and the furnace outlet, and the oxygen concentration in the furnace is about 15 %, And there is no particular problem because the balance is kept in that state while operating under a certain condition, but once the condition of the treated material 3 is changed, the incinerator is changed accordingly. If the amount of exhaust gas destined for the vehicle is changed, the flow rate balance will be disrupted for some period from the time of the change. That is, when the exhaust gas amount for the incinerator is reduced along with the change of the condition of the processing material 3, the exhaust gas blows out from the furnace inlet and the furnace outlet, which causes a problem in the working environment. When the amount of exhaust gas for the incinerator is increased in accordance with the above, the amount of external air sucked from the furnace inlet and the furnace outlet increases, and as a result, the treatment material 3 is cooled by the air near the furnace inlet and the outlet, Occasionally, a baking temperature could not be obtained and a baking defect sometimes occurred.

The present invention has been made in view of the above circumstances, and a continuous dry baking apparatus for preventing a large amount of air from being sucked in from an inlet and an outlet of a dry baking furnace or blowing out of a furnace exhaust gas at the time of changing a condition of a processing material. It is an object of the present invention to provide a control method of.

Means for Solving Problems The present invention is to continuously pass a treatment material coated with a coating material through a dry baking oven to dry-bake the coating material and guide exhaust gas from the dry baking oven to an incinerator. Incinerating the paint solvent evaporative gas contained in the exhaust gas, and at least a part of the obtained incineration exhaust gas is introduced into the dry baking furnace as a heat source for dry baking, and is also introduced into the dry baking furnace. In the control method of the continuous drying baking apparatus of the paint, which is designed to adjust the furnace temperature of the dry baking furnace by mixing the external cooling air with the high temperature incinerating exhaust gas, the flow rate of the incinerating exhaust gas guided from the incinerator to the dry baking furnace An incinerator exhaust gas flow rate detecting means for a dry baking furnace for detecting and a cooling air intake flow rate detecting means for detecting an intake amount of cooling air are provided, and the dry baking furnace is also provided. The exhaust gas flow rate detecting means for the incinerator that detects the flow rate of the exhaust gas guided to the incinerator is provided, and the total amount of the incineration exhaust gas and the cooling air introduced into the dry baking furnace is the exhaust gas guided from the dry baking furnace to the incinerator. It is characterized in that it is controlled so as to hold a value according to the flow rate.

Action In the control method of the continuous dry baking apparatus as described above,
The total amount of incineration exhaust gas and cooling air amount (intake amount) introduced into the dry baking furnace should be kept at a value corresponding to the flow rate of exhaust gas introduced from the dry baking oven to the incinerator, that is, the total amount should be The exhaust gas flow rate to the incinerator is controlled so that it will always be a constant ratio (for example, 90%), so the amount of exhaust gas sucked and exhausted from the dry baking furnace to the incinerator was changed in accordance with changes in the processing material conditions. Even at this point, a large amount of exhaust gas is blown out from the inlet and outlet of the drying furnace, and on the contrary, a large amount of outside air is sucked in from the inlet and outlet, and as a result, the working environment is deteriorated due to the emission of exhaust gas, On the contrary, it is possible to effectively prevent the situation where the required baking temperature cannot be obtained due to the intake of air.

Embodiment An embodiment of the present invention will be described below with reference to FIG. Note that in FIG. 1, the same elements as those shown in FIG. 2 which have already been described are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, a gas flow meter 30 as a means for detecting the flow rate of incineration exhaust gas for a dry baking furnace for detecting the flow rate of the incineration exhaust gas guided from the incinerator 10 to the dry baking furnace 1 is provided in the main pipe 14a of the return gas pipe 14. It is provided. Further, the upstream side of each cooling air intake passage 21 for introducing the cooling air into the circulation passage 20 of each zone 1A to 1N of the dry baking furnace 1 is connected to the common cooling air intake pipe 31, and the common cooling A gas flow meter 32 as a cooling air intake flow rate detecting means for detecting the amount of cooling air intake from the outside is provided in the intake air intake pipe 31.
And a damper 33 for adjusting the intake amount of cooling air. Then, the detection value of the gas flow meter 30 as the incineration exhaust gas flow rate detection means for the dry baking furnace and the detection value of the gas flow meter 32 as the cooling air intake flow rate detection means are input to the flow rate instruction control device (FIC) 34. To be done. This flow rate instruction control device 34 is based on the detection values of the gas flowmeters 30 and 32, and is the total amount of the incineration exhaust gas flow rate introduced into the dry baking furnace 1 and the cooling air intake flow rate (that is, the total introduction amount to the dry baking furnace 1). Flow rate) is a constant value corresponding to the gas flow rate detected by the gas flow meter 8 as exhaust gas flow rate detection means for the incinerator provided in the exhaust gas pipe 5 (that is, the exhaust gas flow rate guided from the dry baking furnace 1 to the incinerator 10). The damper 33 of the common cooling air intake pipe 31 is controlled so that the value becomes a value. For example, the opening degree of the damper 33 is controlled so that the total amount always maintains a constant ratio of about 90% with respect to the flow rate of the exhaust gas guided from the dry baking furnace 1 to the incinerator 10. The damper 24 provided in each branch pipe 14b of the return gas pipe 14 is controlled by the temperature instruction control device 26 based on the temperature detected by the temperature sensor 25.

In the apparatus as shown in FIG. 1, the conditions such as the line speed of the processing material 3, the width of the processing material 3, or the amount of solvent per unit area of the coating material applied to the processing material 3 are changed, and a dry baking furnace is used. When the furnace exhaust gas introduced from 1 to the incinerator 10 rapidly increases and the temperature detected by the temperature sensor 25 is higher than the target temperature, the branch pipe 14 of the return gas pipe 14
Although the damper 24 provided in b is squeezed to reduce the amount of incineration exhaust gas introduced into the dry baking furnace 1, the damper 33 of the common cooling air pipe 31 is adjusted in the opening direction by the flow rate instruction control device 34. If the cooling air intake amount increases while the temperature detected by the temperature sensor 25 is lower than the target temperature, the damper 24 operates in the opening direction and the amount of incineration exhaust gas introduced into the dry baking furnace 1 is increased. And the opening degree of the damper 33 is adjusted by the flow rate instruction control device 32 at the same time, and in any case, the total amount of the incineration exhaust gas and the cooling air introduced into the dry baking furnace 1 is from the dry baking furnace 1 to the incinerator. It is controlled so as to be an appropriate amount according to the amount of furnace exhaust gas that is led to 10.

Further, even when the furnace exhaust gas led from the dry baking furnace 1 to the incinerator 10 is drastically reduced due to the change in the conditions of the processing material 3, the opening degree of the damper 24 is changed according to the temperature level detected by the temperature sensor 25. Adjusted and flow rate control device at the same time
The opening degree of the damper 33 is controlled by the 34, and the dry baking furnace 1
The total amount of the incineration exhaust gas and the cooling air introduced into the furnace is controlled so as to be an appropriate amount according to the amount of the furnace exhaust gas introduced from the dry baking furnace 1 to the incinerator 10.

The term "appropriate amount according to the amount of furnace exhaust gas guided from the dry baking furnace 1 to the incinerator 10" is used to prevent the exhaust gas from being blown out of the dry baking furnace 1 from the furnace inlet and outlet. Approximately 90% of the flow rate of the furnace exhaust gas that is introduced from the dry baking furnace 1 to the incinerator 10 in order to make the furnace pressure slightly negative
It is desirable that the amount is about the same.

As described above, even when the flow rate of the furnace exhaust gas guided from the dry baking furnace 1 to the incinerator 10 is drastically changed due to the change of the condition of the treatment material 3, the incineration exhaust gas and the cooling air introduced into the dry baking furnace 1 are introduced. The total amount of the exhaust gas is controlled so as to always maintain a constant rate (preferably about 90%) with respect to the exhaust gas amount of the furnace. It is possible to effectively prevent the occurrence of a situation such as inhalation.

Next, an example in which the control method of the present invention is actually applied will be described.

When continuously baking the paint applied to the metal strip, connect the second strip 0.27 mm thick and 914 mm wide to the rear end of the first strip 0.5 mm thick and 914 mm wide, and then connect the continuous strips. An experiment was conducted in which the top was continuously coated with the coating material and continuously dried and baked. The line speed is 120m / m when baking and drying the first strip.
As in, a furnace exhaust gas amount that leads from the drying baking oven 1 in Inshinereta 10 and 137Nm ³ / min, also the incineration exhaust gas introduced into the drying baking furnace 1 sets the total amount of cooling air 123Nm ³ / min,
Therefore, the amount of invading air from the furnace inlet and outlet is 14 Nm ³ / min
It was set so that Subsequently, in drying and baking the second strip, the line speed was changed to 150 m / min, and accordingly, the amount of furnace gas introduced from the dry baking furnace 1 to the incinerator 10 was changed to 203 Nm ³ / min. The total set amount of incineration exhaust gas and cooling air to be introduced into the furnace is 183 Nm ³ / min (thus, the amount of air entering from the furnace inlet and outlet is 20 Nm ³ / min)
As a result, continuous dry baking was performed. As a result, neither abnormal blow-out from the furnace inlet nor outlet nor excessive air intake was observed even at the time of switching from the first strip to the second strip.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the control method of the continuous dry baking apparatus of the present invention, when the furnace exhaust gas amount introduced from the dry baking furnace to the incinerator is changed in accordance with the change in the condition of the treated material. In this case, it is possible to effectively prevent exhaust gas from being blown out from the inlet and outlet of the dry baking furnace, and conversely sucking in a large amount of outside air from the inlet and outlet, resulting in deterioration of the work environment or required baking. There is no possibility that the temperature cannot be obtained and the seizure failure occurs.

[Brief description of drawings]

FIG. 1 is a system diagram showing an example of a continuous dry baking device for carrying out the method of the present invention, and FIG. 2 is a system diagram showing an example of a conventional continuous dry baking device. 1 ... Dry baking furnace, 3 ... Treatment material (metal strip),
8 ... Gas flowmeter as exhaust gas flow rate detection means for incinerator, 10 ... Incinerator, 30 ... Gas flowmeter as incinerator exhaust gas flow rate detection means for dry baking furnace, 32 ...
... Gas flowmeter as a means for detecting the intake amount of cooling air, 33 ...
… Damper for adjusting the intake amount of cooling air, 24 …… Damper for adjusting the amount of incineration exhaust gas introduced.

Claims (1)

[Claims] 1. A treatment material (3) coated with a coating material is continuously passed through a dry baking oven (1) to dry-bak the coating material, and an exhaust gas from the dry baking oven (1) is injected into an incinerator. (10) is introduced to incinerate the paint solvent evaporative gas contained in the exhaust gas, and at least a part of the incinerated exhaust gas obtained is introduced into the dry baking furnace (1) as a heat source for dry baking, In a method for controlling a continuous drying / baking apparatus for paints, which adjusts the furnace temperature of the dry baking furnace (1) by mixing the high temperature incineration exhaust gas introduced into the dry baking furnace (1) with external cooling air. An incinerator exhaust gas flow rate detection means (30) for a dry oven, which detects a flow rate of an incinerator exhaust gas that is guided from the incinerator (10) to the dry oven (1), and a cooling air intake that detects an intake amount of cooling air. Input flow rate detection means (32) Together preferably provided, Inshinereta from the dry baking oven (1) (10)
An exhaust gas flow rate detection means (8) for an incinerator for detecting the flow rate of exhaust gas guided to the dry baking furnace (1) is provided so that the total amount of the incineration exhaust gas and the cooling air introduced into the dry baking furnace (1) is the dry baking furnace (1). A method for controlling a continuous coating and drying device for coating material, which is controlled so as to maintain a value corresponding to a flow rate of exhaust gas guided from a fuel cell to an incinerator (10).