JPS61200877A - Control of painting oven - Google Patents

Abstract

PURPOSE:To secure safe operation, by calculating the concn. of the solvent in each region within a drying oven from the solvent evaporation curve of a paint to be used and the temp. rising speed of a treating material and setting the exhaust gas corresponding thereto. CONSTITUTION:Each zone is connected to an incinerator 7 form furnace exhaust gas pipings 5a-5e through a blower 6 and the solvent evaporation gas of a paint is incinerated. A heat exchanger 9 preheats clean air tanken in by a blower 11 and preheated air is blown to each zone of a drying oven 4 by recirculation blowers 12a-12e. The plate passing speed of a treating material 2 is set to a treatment speed and the furnace exhaust dampers 18a-18c of exhaust gas pipings 5a-5c are regulated by regulators 19a-19c corresponding to the output of a detector 16 for detecting the number of rotations of the take-up roll of a roll coater 3 and the outputs of detectors 17a-17c of the furnace exhaust gas flow amounts of furnace exhaust gas pipings 5a-5c.

Description

[Detailed Description of the Invention] (Industrial Application Field) This specification describes a method for controlling a coating oven, which can easily and easily eliminate dangers such as explosion and ignition in a continuous baking drying oven without hindering workability or productivity. We propose the results of development research on how to avoid this and ensure safe operation.

Energy-saving systems for continuous baking and drying ovens for paint films Various methods have been proposed for this purpose, and a typical example is passing treated materials with paint on them through a continuous baking and drying oven. By guiding the furnace exhaust gas to an incinerator, the solvent evaporation gas contained in the furnace exhaust gas is sequentially and continuously incinerated, and a heat exchanger is installed in the exhaust path of the incineration gas by this incinerator to heat clean air. It is well known to conduct dry baking of paint films by introducing air into a continuous baking oven. Appropriate control of the heating atmosphere in such a continuous baking and drying furnace is a mode of utilization of the present invention.

(Prior art) The heating atmosphere using preheated clean air in this type of continuous baking drying oven is divided into several zones in the direction of sheet passing, for example, through all of the first to fifth zones, and the skin heat atmosphere temperature in each zone is kept constant. According to the detection results, the damper of the dilution air intake and the damper of the clean air piping are controlled by alternately opening and closing, and the furnace exhaust gas containing solvent evaporation gas is sucked all at once by a blower through the exhaust gas piping, which has a damper for each zone. It was supposed to lead to the Incinerator.

(Problem to be solved by the invention, beans) The 11K degree of solvent vapor in each part of the continuous baking to drying oven, that is, the first to fifth zones of the drying process, is determined by the temperature increase rate of the painted steel plate and the g content in the paint. It is determined by the evaporation rate of the agent and the exhaust gas flow rate depending on the throttle of the damper installed in the exhaust gas piping of each zone. On the other hand,
Until now, sufficient consideration has not been given to the control of such dynamic factors, and as a result, even if Zone F is in a heated atmosphere where the concentration of solvent is much lower, air supply and circulation operations are added unnecessarily, resulting in heat loss. This was a cause of energy consumption.

(Means for Solving the Problems) This invention heats clean air using a heat exchanger installed in the exhaust path of incineration exhaust gas by an incinerator, and uses only this heated air to eliminate blood clots. Used when drying treated materials in a continuous baking drying oven! ! Calculate the concentration of m in each part of the drying oven from the evaporation curve of the solvent in the material and the temperature increase rate of the process, set the exhaust gas emission amount of each part of the drying oven accordingly, and calculate the concentration of m in each part of the drying oven. solvent@
This is a method for controlling a coating oven, which is characterized by suppressing the temperature to below a level of explosion danger.

Now, FIG. 1 shows the framework of a continuous baking and drying oven to which the control method according to the present invention is applied.

In the figure, 1 is a coating device, 2 is a processing material, 3 is a roll coater, and 4
1 is a drying oven, and a - e denotes the first to fifth zones, which are divided into several sections in the direction of sheet passing, in the drying oven.
The evaporated solvent gas in the paint is incinerated by connecting it to the incinerator trough through the incinerator. In the figure, 8 is a fuel pipe of the incinerator trough, 9 is a heat exchanger, and 1o is a chimney.

The heat exchanger 9 preheats the clean air taken in by the blower 114, and each zone of drying F4 is heated by a CII ring blower l.
2a-1255. 13°14 in the diagram
15 is a V4 regulating damper for hot air and cold air; 15 is a V4 regulating damper 13.
14 (note that this control system is omitted from the illustration for areas other than the first zone a for the sake of abbreviated representation of !lF1 in the figure).

In the above-mentioned points, the continuous baking drying oven 4 follows the conventional structure, and in addition, the passing speed of the processing material 2 is set as the processing speed, and a detection meter 16 for the number of rotations of the winding roller of the roll coater 3 is used. , a detector 1 for detecting the flow weight of the furnace exhaust gas in the furnace exhaust gas pipes 5a to 5e, and in most cases up to 5c.
Exhaust gas piping 5a to 5c according to each output of 74 to 17C
Controllers 19a to 1 that control the throttling of 18a to 180 of the Y4 regulating dampers 18a to 186 for the furnace exhaust gas passing through the
90 will be provided.

In any case, in a steady state, the amount of heat of the clean air heated by the heat exchanger 9, that is, the amount of input heat, and the amount of heat required for drying and baking the m-film are balanced, and there is no need to control the amount of input heat.

If the amount of heat input is too large, the temperature of the heated clean air is detected by the thermometer on the outlet side of the blower 12, and the dilution air intake and inlet damper 14 are opened, and at the same time, the damper 18 of the clean air pipe is throttled. This is done via the controller 15.

(Function) Now, the concentration of the solvent vapor in each zone of the baking drying oven 4 circles is determined by the temperature increase rate of the treatment Ir2, the evaporation rate of the solvent in the coating film, and the exhaust gas flow rate due to the furnace exhaust gas vsi regulating dampers 18a to 18e. It is determined by Q0~q.

For example, the processing speed K L (m/se
c) Processing material temperature [MT and solvent evaporation tWO
) shows the relationship, but the line speed at the foot of the solvent evaporation in each zone is L.
', the temperature of the treated steel sheet becomes MT' and the solvent evaporation sound also becomes W'.

Therefore, processing speed is fast! I, the first zone a and the second zone b
Then, most of the solvent evaporates, and of course the exhaust gas flow in the first and second zones *Q, Q, is % tQ4 + and q
It needs to be larger than 5, and the exhaust gas it in each zone at this time is: Ql %5-K x W1~B ("8/m+in)
HH+ (1) Here W0~. : Solvent evaporation amount (kg/H) for each /-ton, K: Calculated as a constant determined by bath agent components.

Next, by increasing the processing speed KL to b', for example, the solvent evaporation amount @W' changes, so the solvent evaporation amount w0 in the first zone a and the third zone changes significantly, especially W, To increase this, it is necessary to significantly reduce the exhaust gas current Q and to significantly increase the exhaust gas flow rate Q.

Here, according to FIG. 1, the processing speed detector 16 calculates the bath agent brought into the paint fW (this also calculates the processing material temperature ffiMT in each zone, and calculates the temperature in each zone in the exhaust gas flow tv4 meter). Set〇Exhaust gas flow rate controller 19
a~190 is the amount of solvent evaporation w0~W depending on the given processing material temperature MT,~MT.

is calculated, and the exhaust gas flows tQ0 to q are set using equation (1).

The control system must include a total of 17a to 17c, fL adjustment dampers 18a to 180, and exhaust gas flow rate controllers 19a to 19Ci.

In the above specific example, these control systems are not incorporated in zone 4.5, but the solvent composition, solvent evaporation curve,
If there is a possibility that the amount of solvent evaporation in the 4th zone and 5th zone will increase due to steel plate temperature, etc., safety can be further ensured by installing a control system similar to that in zones 1 to 8 in each of these zones. Needless to say, it is maintained at

In addition, the amount of solvent brought into the paint W and the amount of solvent evaporated in each zone W1 to W
, means WW + w, + w, + w, + w.

The relationship between the amount of carried-in solvent W and the main exhaust gas flow rate Q0+
W, + W, means Qo-K. W (NXnfi/h) ・-
(2) Where W: Amount of solvent brought into the paint (''/h), Ko:
It is expressed as a constant determined by the solvent components.

(Example) 1゜ Dimensions and thickness of treated material in drying oven @ 300℃ 0.2
7 x width 914ul, line speed gi 100m/
An example in which the solvent isophorone is used is described below with a wet coating thickness of 409/m'' (dry coating thickness of 20 g/m'').

The lower explosive limit of isophorone is 0.8 kg, and under these conditions, the amount of solvent *W brought into the drying oven is 110 kg/W.
h and the exhaust gas flow rate Q to maintain safety. ! Ko
1 s ONrn8/min in W.

Conventionally, this Qo is the exhaust gas flow of each zone.

If it is equally distributed to each zone, Q w 30 ''/min will be 1 to 5. From the amount of solvent evaporation in each zone at this time, the amount of solvent in each zone is W, = 42 coefficient x 110 kg/h - 46 kg/hW =
26%Xll0I-281W; 15%X110
# Ki16 1 δ, so Q, -60Nm'/m1nql -40
"" / win Qδ-201 Q4 15 1 Q, = 15# exhaust gas current setting was made. As a result, it was possible to operate safely ◇ 2. In Example 1, the drying oven temperature was changed to 820"O and the line speed was changed to 120 m/min, and the wet coating thickness was 40117m" (dry coating thickness 2017T11
When operating at 5, the amount of solvent tw in the drying oven is 181%, which is Q6 * i 80 ''/min.

The amount of solvent evaporation in each zone at this time is Wll! 25chi XI 132 kl'/h -33kli/hW =
45chi x 1δZI = 591 W = 20%
r Q8=35# Q4m l ONm"/win Q, the exhaust gas flow rate was set to 10 1 for snow, and the operation could be performed safely.

1 due to the difference in line speed, drying oven temperature, and IK degree.
Solvent evaporation amount W0 for each zone, zone 2, and zone 3
W8, on the other hand, the exhaust gas flow rate for maintaining safety Q□~
It is clear that Q8 will also change significantly.

(Effects of the Invention) According to the present invention, dynamic factors such as the number of processing times of the treated material passed through the continuous baking drying furnace and the resulting relative changes in the tI agent evaporation gas concentration in each zone in the furnace can be controlled as control factors. By doing so, the drying operation can be appropriately controlled without causing explosion or ignition in the furnace (more effective and efficient continuous baking).

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the continuous baking drying furnace, and FIG. 2 is a graph showing the dependence of the temperature of the treated material and the amount of solvent evaporation on the processing speed in each zone in the furnace. - Ripples and gourds Σρ

Claims (1)

[Claims] 1. Clean air is heated by a heat exchanger installed in the exhaust path of incineration exhaust gas by the incinerator, and only this heated air is used to dry treated materials with paint attached in a continuous baking drying oven. , the solvent concentration in each part of the drying oven is calculated from the solvent evaporation curve of the paint used and the temperature rise rate of the treated material, and the exhaust gas emissions of each part of the drying oven are set accordingly. A method for controlling a painting oven, characterized by suppressing the concentration of a solvent in a part to a concentration that is dangerous for explosion.