JPH0333388B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method of operating a continuous paint drying and baking oven. [Prior Art] Conventionally, a method for operating a continuous paint drying oven has been disclosed in JP-A-60-54764, and the features of this method will be explained with reference to FIG. 1 is a dry baking oven with three zones 1a, 1
The zone is divided into zones b and 1c, and each zone is provided with a header 2 that spouts hot air for drying and baking, sandwiching the conveyance path of 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, where a burner 7 operated by the temperature controller 6 burns off the solvent vapor contained in the furnace exhaust gas, making it odorless. The incineration exhaust gas from the incinerator 5 is released into the atmosphere from a chimney 9 through a duct 8. Note that 12 is a heat exchanger provided in the duct 8, which preheats the furnace exhaust gas to the incinerator 5. 13 is a heat exchanger as an indirect heating device provided downstream of the heat exchanger 12 in the duct 8, and is a heat exchanger that serves as an indirect heating device and is installed in the duct 8 without heating the clean air.
4a, and a high temperature side heat exchanger 13b, which heats to a high temperature and supplies it to the duct 14b. Clean air supplied to both heat exchangers 13a and 13b is regulated by an on-off valve 20 operated by an air supply amount controller 19. Further, a displacement controller 10 is operated upstream of the blower 4 in the duct 3, and is operated to open and close so that the concentration of solvent evaporated gas in the drying and baking furnace 1 is outside the explosion limit (for example, 1/4 concentration of the explosion limit). An on-off valve 11 is provided, and the air supply amount controller 19 is linked with an exhaust amount controller 10, and the on-off valve 20 is configured to always supply clean air to match the exhaust amount from the drying and baking furnace 1. It opens and closes. Each of the heat exchangers 13
The clean air heated in a and 13b is transferred to the duct 14
a, 14b, merge after passing through flow rate control valves 15a, 15b, and are ventilated by the blower 16 into zones 1a, 14b.
The atmosphere is supplied to the header 2 through a duct 17 together with the atmosphere from 1b and 1c. The control valves 15a, 15b are connected to each zone 1a, 1
The clean air is opened and closed by a temperature (indicator) controller 18 that operates depending on the temperature inside the duct 17 or the header 2 of b and 1c, and the amount of mixture of both is adjusted to 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. The temperature of the gas ejected from the header of the 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 one zone becomes lower than a predetermined temperature, the opening degree of the control valve 15b of the first 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, if the amount of clean air flowing into the high temperature side heat exchanger 13b increases, the temperature and pressure of the clean air on the outlet side of the high temperature side heat exchanger 13b will change. It also affects the zone. For this reason, stable temperature control is not possible, and stable line operation is not possible, resulting in products with defective baking temperatures. The present invention aims to stabilize the temperature control of each zone of the drying and baking furnace and stabilize the line operation. [Means for Solving the Problems] The present invention involves continuously passing the treated material to which the paint is attached through each zone of a drying and baking furnace, and drying and baking the paint by blowing heated clean air onto the treated material. In a method for operating a continuous drying and baking furnace for paint, in which the generated furnace exhaust gas 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) adjusting the incineration temperature output from the incinerator according to the amount of heat required for each zone of the drying and baking furnace; (B) adjusting 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, the amount of clean air is changed by a high temperature side heat exchanger and a low temperature side heat exchanger installed in the incineration exhaust gas exhaust path of the incinerator according to the required heat amount of the drying and baking furnace. (C) When the heated air temperature regulated 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 in each zone of the baking furnace, the pressure on the outlet side of the high-temperature heat exchanger is controlled at a constant level, and the paint is dried in the furnace using only heated air whose temperature and pressure are regulated. It is designed to be baked on. [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. 1 is a dry baking oven with three zones 1a, 1b, 1
Each zone is provided with a header 2 that blows out hot air for drying and baking, with a conveyance path for the treated material W coated with paint placed in each zone. Further, the furnace exhaust gas generated in each zone reaches the incinerator 5 via the duct 3 and the blower 4, where the solvent evaporation gas contained in the furnace exhaust gas is incinerated by a burner 7 operated by a temperature indicating controller 33, which will be described later. The odorless incineration exhaust gas from the incinerator 5 is released into the atmosphere from a chimney 9 through a duct 8. The duct 8, which serves as a discharge route for the incineration exhaust gas of the incinerator 5, is provided with a low temperature side heat exchanger 21 and a high temperature side heat exchanger 22.
Clean air is introduced through the interlocking valve 23.
In addition, the high temperature side heat exchanger 22 includes a low temperature side heat exchanger 2.
The heated air heated in step 1 and the clean air flowing in through the interlocking valve 24 are mixed and introduced. A blower 25 is provided on the inlet side of the interlocking valves 23 and 24 for supplying clean air into the low-temperature side heat exchanger 21 and the high-temperature side heat exchanger 22. Air pressure adjustment valve 2 to adjust
6 and an air filter 27 for purifying clean air. The high temperature side heat exchanger 22 and the drying baking furnace 1 are connected to the duct 2
A plurality of blowers 16 are disposed between the duct 28 and each zone of the drying and baking furnace 1, and a flow rate regulating valve 29 for adjusting the amount of heated air is provided between each blower 16. has been inserted. In addition, a heated air supply duct 28 and a discharge duct 8
In between is a control valve 30 that prevents the heated air output from the high temperature side heat exchanger 22 from reaching a predetermined temperature or higher.
is provided in the duct 28, and the duct 2
A flow rate indicator 31 for measuring the air flow rate passing through the duct 8 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 is provided with a temperature indicating controller 33 that adjusts the combustion temperature of the incinerator 5 according to the opening degree of the interlocking valve 23. A furnace exhaust gas flow rate indicator 34 and a furnace exhaust gas flow rate control valve 35 are provided between the blower 4 and the drying and baking furnace 1 to adjust the flow rate of the furnace exhaust gas. In the above configuration, clean air supplied from the blower 25 is blown to the drying and baking furnace 1 heated by the low temperature side heat exchanger 21 and the high temperature side heat exchanger 22. The blowing temperature in this case 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 amount of air heated by the high temperature side heat exchanger 21 and the amount of air not heated by the low temperature side heat exchanger 21 are linked so that the temperature of the heated air output from the high temperature side heat exchanger 22 becomes the set temperature. valves 23 and 2
Controlled by 4. In addition, a low temperature side heat exchanger 21 and a high temperature side heat exchanger 2
If the adjustment of the heated air temperature in step 2 exceeds the upper limit, the bleed valve 30 is operated to open the heated air so that the heated air temperature on the outlet side of the high temperature side heat exchanger 22 reaches the set value. Release into the atmosphere. Further, 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. The heated air whose temperature and pressure have been adjusted is supplied to each blower 16 through a flow rate control valve 29 that is set according to the temperature required by each zone of the drying and baking furnace 1. As described above, in this drying and baking oven 1, drying and baking of the paint is carried out 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. The incinerator 5 is based on clean air, and can perform stable combustion and incineration using fuel and furnace exhaust gas containing solvent evaporation gas, without particularly requiring 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). 23 is detected and controlled by the temperature indicating controller 33 of the incinerator 5 so that the combustion incineration temperature of the incinerator 5 becomes the set temperature. Incineration exhaust gas from the incinerator 5 is transferred to an exhaust duct 8, a high temperature side heat exchanger 22,
It is radiated into the atmosphere from the chimney 9 via the low-temperature side heat exchanger 21. The method of the present invention uses simple equipment and piping, and uses heated air with controlled temperature and pressure in the drying baking oven, so it eliminates factors that adversely affect the quality of paint surfaces such as ducts. Can be done. Table 1 shows the specifications of actual operation according to the method of the present invention. In Table 1, type A is the production volume of treated materials.

[Table] Since the (t/h) is small and the baking temperature is low, the amount of heat required in the drying baking oven is small. Type B has a large production amount (t/h) of treated material and a high baking temperature, so a large amount of heat is required for the drying baking furnace. In both cases, the temperature of the gas ejected from the header of the drying baking furnace can be controlled to the set temperature, allowing stable operation and eliminating the occurrence of defective baking products. As is clear from the above embodiments, the present invention heats clean air with incinerator exhaust gas,
By performing dry baking in a baking drying oven using only this heated clean air, the following effects could be achieved. The amount of heat supplied to the drying and baking oven varies greatly depending on the product type, but even within the same product type, it varies depending on the strip width, thickness, etc. Generally, there is a long time lag when changing the temperature of high-temperature gas via a heat exchanger, but as mentioned above, this system automatically controls the combustion incineration temperature of the incinerator based on the amount of heat required for the drying oven. The amount of heat supplied to the drying and baking oven is controlled by the amount of heated air that is controlled by the temperature, so even if the amount of heat required for the drying and baking oven changes suddenly, such as the width of the strip or the thickness of the strip, the heat exchanger on the low temperature side will supply the same amount of heat. By changing the ratio of the amount of clean air to be heated, the necessary amount of heat can be quickly supplied to the drying and baking furnace. In addition, if changes in strip width, thickness, etc. are detected in advance and feed forward control is performed to input the necessary amount of heat into the drying oven, changes in strip width, thickness, etc. Even if there is a change, work such as passing the plate through until the temperature of the drying and baking furnace becomes stable becomes unnecessary. The oxygen concentration in the incineration exhaust gas of the incinerator
Since the incineration temperature of the incinerator 8 can be operated at a high temperature of 15 to 17% in the range of 800 to 900°C, it is possible to efficiently operate a wide variety of products with greatly different production volumes (t/h). Since the arrangement and piping are simple, equipment costs are low, and the operation system is simple, making operation easy. [Effects of the Invention] The present invention continuously passes the treated material to which paint has been adhered through 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 includes: incinerating solvent evaporated gas in the furnace exhaust gas by guiding it to an incinerator, and heating clean air blown onto the treated material by the energy of the incineration exhaust gas from the incinerator; (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 adjusted; In order to control the heating temperature to be approximately equal, the heating temperature of the clean air is adjusted according to the required heat amount of the drying and baking furnace using a high temperature side heat exchanger and a low temperature side heat exchanger provided in the incineration exhaust gas exhaust path of the insulator. (C) When the temperature of the heated air regulated 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) Each zone of the drying and baking furnace In order to accurately control the temperature, the pressure on the outlet side of the high-temperature heat exchanger is controlled at a constant level, and the paint is dried and baked in the furnace using only the heated air whose temperature and pressure have been adjusted. This is what I did. Therefore, it becomes possible to stabilize the temperature control of each zone of the drying and baking furnace and stabilize the line operation.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram showing an embodiment of the present invention;
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 control valve, 30...Bleed valve, 32...Pneumatic pressure indication control valve.

Claims (1)

[Scope of 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 sent to an incinerator. In the 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 the solvent evaporated gas in the furnace exhaust gas is incinerated and the clean air blown onto the treated material is heated by the energy of the incinerator incineration exhaust gas. The incineration temperature output from the incinerator is adjusted according to the amount of heat required for each zone of the furnace, and (B) 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. In order to control the heating temperature, the heating temperature of the clean air is adjusted according to the required heat amount of the drying and baking furnace using a high temperature side heat exchanger and a low temperature side heat exchanger installed in the incineration exhaust gas discharge path of the insulator. C) When the heated air temperature regulated 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, and (D) The temperature of each zone of the drying and baking furnace is In order to accurately control the heat exchanger, the pressure on the outlet side of the high-temperature side 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. How to operate a continuous paint drying oven.