JPS6249974A - Operating method for continuous drying and baking device for paint - Google Patents

Abstract

PURPOSE:To stabilize the temp. control of each zone of a drying and baking furnace and to stabilize a line operation by drying and baking a paint in the drying and baking furnace only by the heating air which is controlled in temp. and pressure. CONSTITUTION:The heating temp. of clean air is controlled by a high temp. side heat exchanger 22 and a low temp. side heat exchanger 21 provided to a discharge route for the waste incineration gas from an incinerator in order to control the incineration temp. outputted from the incinerator 5 according to the quantity of the heat required for the zones 1a-1c of the drying and baking furnace 1 and to control the flow rate of the waste furnace gas discharged from the furnace 1 and the flow rate of the heated clean air to be supplied to the furnace 1 in such a manner that both flow rates are made approximately equal. The heating air is released to the outside when the temp. of the heating air controlled by the heat exchangers 22, 21 exceeds the control range. The pressure on the outlet side of the heat exchanger 22 is controlled constant in order to exactly control the temp. in the respective zones of the furnace 1. The drying and baking in the furnace 1 are executed only by the air which is controlled in temp. and pressure.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of operating a continuous drying and baking oven for paint.

[Prior Art] Conventionally, a method for operating a continuous paint drying oven has been disclosed in Japanese Patent Application Laid-Open No. 80-54784, and the features of this method will be explained with reference to FIG. 1 is a dry baking oven divided into three zones la, 1b, and 1c,
Each zone is provided with a header 2 that blows out hot air for drying and baking, sandwiching the conveyance path for the treated material W coated with paint. Further, the furnace exhaust gas generated in each zone reaches the incinerator 5 via the duct 3 and the blower 4.
Here, the burner 7 operated by the temperature controller 6 incinerates the solvent evaporation gas contained in the furnace exhaust gas, and the odorless incinerator exhaust gas from the incinerator 5 is released into the atmosphere from the chimney 9 via the duct 8. Ru.

Note that 12 is a heat exchanger provided in the duct 8, which preheats the furnace exhaust gas to the incinerator 5. Reference numeral 13 denotes a heat exchanger as an indirect heating device provided downstream of the heat exchanger 12 in the duct 8, and a low temperature side heat exchanger 13a that supplies clean air to the duct 14a without heating it almost.
The clean air supplied to the two heat exchangers 13a and 13b consisting of the high temperature side heat exchanger 13b heated to a high temperature and supplied to the duct 14b is supplied by an on-off valve 20 operated by the air supply 1m meter 19. be adjusted.

Moreover, -hm of the blower 4 of the duct 3 has a displacement of 31
An on-off valve 11 is provided, which is operated by a total of 10 and opens and closes so that the concentration of solvent evaporated gas in the drying and baking furnace l is outside the explosion limit (for example, 1/4 concentration of the explosion limit). A total of 19 is interlocked with the displacement controller 10, and an on-off valve 20
is always opened and closed to supply clean air in proportion to the amount of exhaust from the drying and baking furnace 1. The clean air heated by each of the heat exchangers 13a and 13b is transferred to a duct) 14a,
14b, flow rate control valves 15a, 15b, and then merge together, and the blast air 16 is supplied to the header 2 via a duct 17 together with the atmosphere from the zones 1a, 1b, and the IC.

The yA control valves 15a, 15b are connected to each sea 71a, 1b, 1
A temperature (indicator) controller 18 that is operated depending on the temperature inside the duct 17 or the header 2 of c is opened and closed to adjust the amount of mixture of the two and adjust the supplied clean air to a predetermined temperature.

That is, the conventional method described above balances the exhaust volume and air supply volume of the drying and baking furnace 1, and adjusts the supply volume of clean air to the low-temperature side heat exchanger 13a and the high-temperature side heat exchanger 13b by the WA clause. The temperature of the gas ejected from the heater 2 of the drying and baking furnace 1 is regulated.

[Problems to be Solved by the Invention] However, the above conventional method has the following problems.

For example, when the temperature of the l zone becomes lower than a predetermined temperature, the opening degree of the control valve 15b of the l zone is increased to increase the amount of clean air flowing into the high temperature side heat exchanger 13b, and the ejection temperature from the header 2 is increased. However, since the amount and temperature of the exhaust gas from the incinerator 5 entering the high temperature side heat exchanger 13b are constant, if the amount of clean air is increased, the temperature of the high temperature side heat exchanger 13b will be increased. The temperature of the clean air on the outlet side is lower than before. Further, as the flow rate of the heat exchanger increases, the pressure loss of the fluid flowing through it increases, so if the amount of clean air is increased, the clean air pressure on the outlet side of the high temperature side heat exchanger 13b decreases. In this way, the high temperature side heat exchanger 13
If the amount of clean air flowing into section b becomes large, the temperature and pressure of the clean air at the outlet side of the high temperature side heat exchanger 13b will change, so it is necessary to apply 1 sugiya to other zones where the temperature could be controlled in the past. As a result, stable temperature control is not possible, and stable line operation is not possible, resulting in products with defective baking temperatures.

The first objective of the present invention is to stabilize the temperature control of each zone of the drying and baking furnace and to stabilize the line operation X.

[Means for Solving the Problems] The present invention continuously passes the treated material to which paint 4 has been applied through each zone of a drying and baking furnace, and blows heated clean air onto the treated material to dry and bake the paint. In a method for operating a continuous paint drying and baking furnace, the furnace exhaust gas generated is guided to an incinerator to incinerate solvent evaporation gas in the furnace exhaust gas, and the clean air blown onto the treated material is heated by the energy of the incineration exhaust gas from the incinerator. (A) Adjust the incineration temperature output from the incinerator according to the required heat of each zone of the drying and baking furnace; (B) Adjust the amount of furnace exhaust gas discharged from the drying and baking furnace and supplying it to the drying and baking furnace. In order to control the amount of heated clean air to be approximately equal, a high-temperature side heat exchanger and a low-temperature side heat exchanger installed in the incineration exhaust gas exhaust path of the insulator are used to clean the air according to the required heat of the drying and baking furnace. (C) When the heated air temperature adjusted by the high-temperature side heat exchanger and the low-temperature side heat exchanger exceeds the adjustment range, the heated air is discharged to the outside of the system; (D) drying. In order to accurately control the temperature of each zone of the firing furnace,
The pressure at the exit side of the high-temperature heat exchanger is controlled to be constant, and the paint is dried and baked in the furnace using only the heated air whose temperature and pressure have been adjusted.

[Function] According to the present invention, it becomes possible to stably supply heated air whose temperature and pressure are adjusted to each zone of the drying and baking furnace, and it becomes possible to stabilize line operation.

[Embodiment] FIG. 1 is a piping system diagram showing an embodiment of the present invention, and the same members as in FIG. 2 are given the same reference numerals.

l is a drying and baking oven divided into three zones la, 1b, and lc, and each zone is provided with a bed 2 that blows out hot air for drying and baking across the conveyance path of the treated material W coated with paint. It is. Further, the furnace exhaust gas generated in each zone reaches the incinerator 5 via the duct 3 and the blower 4, where the burner 7 is operated by a temperature indicating controller 33 (described later) to release the solvent evaporation contained in the furnace exhaust gas. The incineration exhaust gas from the incinerator 5, which has been made odorless by incineration, is released into the atmosphere from a chimney 9 via a duct 8.

The duct 8, which serves as a discharge route for the incineration exhaust gas of the incinerator 5, has a low-temperature side heat exchanger 21 and a high-temperature side heat exchanger 22.
Clean air is introduced into the hot side heat exchanger 21 via an interlocking valve 23.

Further, the heated air heated by the low temperature side heat exchanger 21 and the clean air flowing in through the interlocking valve 24 are mixed and introduced into the high temperature side heat exchanger 22 .

On the inlet side of the interlocking valves 23 and 24, there is a blower 2 for supplying clean air into the low temperature side heat exchanger 21 and the high temperature side heat exchanger 22.
5 is provided, and this blower 25 is connected to an air pressure regulating valve 26 for regulating the pressure of the clean air taken in, and an air filter 27 for purifying the clean air.

The high temperature side heat exchanger 22 and the drying and baking furnace 1 are connected by a duct 28, and a plurality of blowers 16 are arranged between the duct 28 and each zone of the drying and baking furnace 1.
A flow rate control valve 29 for adjusting the amount of heated air is inserted between the air conditioner 6 and the air flow rate control valve 6 .

Further, a control valve 30 is provided between the heated air supply duct 28 and the discharge duct 8 to prevent the heated air output from the high temperature side heat exchanger 22 from reaching a predetermined temperature or higher. A flow rate meter 31 for measuring the air flow rate flowing through the duct 28 and a pressure regulator 32 for adjusting the air pressure inside the duct 28 are provided.

On the other hand, the burner 7 of the incinerator 5 has a combustion temperature of 2151 W depending on the opening degree of the interlocking valve 23.
A temperature Iu controller 33 is provided to control the temperature. Between the blower 4 and the drying and baking furnace l, there is a furnace exhaust gas flow rate indicator controller 34 and a furnace exhaust gas flow rate control valve 35 for adjusting the meteor of the furnace exhaust gas.
is provided.

In the configuration I below, clean air supplied from the blower 25 is blown to the drying and baking furnace l heated by the low temperature side heat exchanger 21 and the high temperature side heat exchanger 22. In this case, the blowing temperature is set so that the amount of furnace exhaust gas output from the drying and baking furnace 1 and the amount of heated air supplied to the drying and baking furnace 1 are approximately equal.

That is, the low temperature side heat exchanger 21 is adjusted so that the temperature of the heated air output from the high temperature side heat exchanger 22 becomes the set temperature.
The amount of air heated by the heat exchanger 21 and the amount of air not heated by the low temperature side heat exchanger 21 are controlled by interlocking valves 23 and 24.

In addition, if the adjustment of the heated air temperature by the low-temperature side heat exchanger 21 and the high-temperature side heat exchanger 22 exceeds the upper limit, the bleed valve 30 is operated to set the heated air temperature on the outlet side of the high-temperature side heat exchanger 22. The bleed valve 30 is opened to release the heated air to the atmosphere.

The air pressure indicator controller 32 adjusts the pressure of the heated air on the outlet side of the high temperature side heat exchanger 22 to the set pressure. This heated air whose temperature and pressure have been adjusted is
The flow is supplied to each of the blowers 16 via an IW fff valve 29, which is set to the temperature required by each zone of the drying oven 1.

As described above, in this drying and baking furnace I, the paint is dried and baked only by heated air whose temperature and pressure are controlled. Furnace exhaust gas containing solvent evaporation gas from the drying and baking furnace 1 is blown to an incinerator 5 via a furnace exhaust gas duct 3 and a blower 4. The amount of furnace exhaust gas is controlled by a furnace exhaust gas flow rate indicator 34 and a furnace exhaust gas flow rate control valve 35 so that the concentration of solvent evaporated gas in the furnace of the drying and baking furnace 1 is at a value required for explosion protection. Incinerator 5
The method is based on clean air, and uses furnace exhaust gas containing solvent evaporation gas and fuel, allowing stable combustion and incineration without the need for combustion air.

The fuel temperature of the incinerator 5 is automatically controlled in the range of 600 to 900°C so that the opening degree of the low temperature side heat exchanger interlocking valve 23 becomes the upper limit value (80 to 100% open). The opening degree of the valve 23 is detected, and the temperature indication of the incinerator 5 is adjusted so that the combustion incineration temperature of the incinerator 5 reaches the set temperature. [)33 to control. The incineration exhaust gas from the incinerator 5 passes through the exhaust duct 8, the high-temperature side heat exchanger 22, and the low-temperature side heat exchanger 21, and is released into the atmosphere from the chimney 9.

The method of the present invention uses simple equipment and piping, and
Since heated air with controlled temperature and pressure is used in the drying and baking oven, it is possible to eliminate factors such as dust that adversely affect the quality of the paint surface.

Table 1 shows the specifications of actual operation according to the method of the present invention. In Table 1, type A has a small production volume (t/h) of treated material and a low baking temperature, so it requires less heat + 5 in the dry baking oven. Ai (t/h
) is large and the baking temperature is high.

The amount required for drying and baking ovens is large. In either case, the temperature of the gas ejected from the drying baking furnace header can be controlled according to the set temperature change, allowing stable operation and eliminating the occurrence of defective baking products.

As is clear from the above embodiments, the present invention was able to achieve the following effects by heating clean air with incineration exhaust gas from an incinerator and performing dry baking in a baking drying oven using only this heated bubble clean air. .

(j) The amount of heat supplied to the drying and baking furnace varies greatly depending on the product type, but even for the same product type, it varies depending on the width, thickness, etc. of the strip. Generally, there is a long time lag when changing the temperature of high-temperature gas via a heat exchanger, but as mentioned above, in this system, the combustion incineration temperature of the incinerator is automatically controlled by the heat h) required for the drying oven. The heat bonding supplied to the drying and baking furnace is performed by the amount of heated air that is temperature controlled. Even if the heat bonding required for the drying and baking furnace suddenly changes, such as the width or thickness of the strip, the heat exchanger on the low temperature side continues to heat the air. By changing the ratio of clean air to air, the required amount of heat can be quickly supplied to the drying and baking oven.

In addition, if changes in the strip width, thickness, etc. are detected in advance and feed-forward control is performed to supply the necessary heat bonding to the drying and baking furnace, changes in the strip width, thickness, etc. Even if there is a change in the temperature, it will no longer be necessary to pass the plate through until the temperature of the drying and baking furnace is stabilized.

■The oxygen concentration in the incineration exhaust gas of the incinerator is 15 to 1
7% higher, incinerator 8 incineration temperature 600~8
Since it can be operated in a temperature range of 00°C, it is possible to efficiently operate a wide variety of products with greatly different production volumes (t/h).

■Equipment costs are low because the layout and piping are simple, and operation is easy because the operating system is simple.

[Effect of the invention 1] The present invention continuously passes the treated material with the paint adhered to each zone of a drying and baking furnace, blows heated clean air onto the treated material to dry and bake the paint, and removes the generated furnace exhaust gas. In a method of operating a continuous drying and baking furnace for paint, the method of operating a continuous drying and baking furnace for paint in which solvent evaporated gas in the furnace exhaust gas is incinerated by an incinerator, and clean air blown onto the treated material is heated by the energy of the incinerator incineration exhaust gas, comprising: (A) the drying and baking furnace; The incineration temperature output from the incinerator is adjusted according to the required amount in each zone of the furnace, and (B) the amount of furnace exhaust gas discharged from the drying and baking furnace and the amount of heated clean air supplied to the drying and baking furnace are approximately equal. In order to control the heating temperature to be equal, the heating temperature of the clean air is adjusted by a high temperature side heat exchanger and a low temperature side heat exchanger provided in the incineration exhaust gas exhaust path of the insulator according to the required heat amount of the drying and baking furnace, (C) When the heated air temperature adjusted by the high-temperature side heat exchanger and the low-temperature side heat exchanger exceeds the W-node range, the heated air is released outside the system, and (D) the temperature of each zone of the drying and baking furnace. In order to accurately control
Controls the pressure at the outlet of the high-temperature heat exchanger to a constant level.

The paint is dried and baked in the furnace using only the heated air whose temperature and pressure are regulated. Therefore, it becomes possible to stabilize the temperature control of each zone of the drying and baking furnace, and to reduce the cost of line operation and nitriding.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram showing one embodiment of the present invention, and FIG. 2 is a piping system diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1... Drying baking furnace, 2... Header, 5... Incinerator, 21... Low temperature side heat exchanger, 22... High temperature side heat exchanger, 23.24... Interlocking valve, 26 ...Opening/closing valve, 28...Duct, 29...Flow rate adjustment valve, 3o.
...Bleed valve, 32...Air pressure indication control valve.

Claims (1)

[Claims] (1) The treated material with paint adhered to it is passed continuously through each zone of a drying and baking furnace, heated clean air is blown onto the treated material to dry and bake the paint, and the generated furnace exhaust gas is guided to an incinerator and the furnace exhaust gas is In a method of operating a continuous drying and baking furnace for paint, which incinerates the solvent evaporation gas contained therein and heats the clean air blown onto the treated material using the energy of the incinerator incineration exhaust gas, (A) the requirements of each zone of the drying and baking furnace; (B) controlling the incineration temperature output from the incinerator according to the amount of heat so that the amount of furnace exhaust gas discharged from the drying and baking furnace is approximately equal to the amount of heated clean air supplied to the drying and baking furnace; , adjusting the heating temperature of the clean air by a high temperature side heat exchanger and a low temperature side heat exchanger provided in the incineration exhaust gas discharge path of the insulator according to the required heat amount of the drying and baking furnace; (C) high temperature side heat exchange; When the heated air temperature adjusted by the oven and low-temperature side heat exchanger exceeds the adjustment range, the heated air is released outside the system. A method for operating a continuous drying and baking furnace for paint, characterized in that the pressure at the exit side of a side heat exchanger is controlled at a constant level, and paint is dried and baked in the furnace using only heated air whose temperature and pressure are adjusted. .