JPH0461953A - Coat drying furnace - Google Patents

Abstract

PURPOSE:To make the operation of a coat drying furnace stable and solve the problems arising from energy conservation by a method wherein the amt. of exhaust air supplied into a combustion device and the amt. of a fresh air supplied to a convection hot air by an air supply means are controlled according to the number of the coated objects in a furnace. CONSTITUTION:A control device 10 computes the number of coated objects A in a furnace 20 using the detection signals supplied by sensors 11 and 12 to the control device and, if the resulting value is O, it reduces the combustion temp. of a combustion device 30 from a predetermined temp. suitable for incinerating treatment to such a value as not to hinder the maintenance of the temp. inside the furnace and also functions as a temp. setting means 50 which brings the combustion temp. of the combustion device 30 when the introduction of the objects A into the furnace is expected back to a predetermined temp. The combustion temp. of the combustion device 30 is regulated by adjusting a burner 30a provided in the combustion device 30.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a paint drying furnace for heating and drying painted objects, and more specifically, the present invention relates to a paint drying furnace that heats and dries painted objects. The furnace is equipped with a combustion device that is supplied with exhaust air containing carbon dioxide, burns the exhaust air, incinerates it, and then discharges it as high-temperature combustion exhaust gas. The present invention relates to a paint drying oven equipped with an air supply means for replenishing the convective hot air for temperature maintenance.

[Conventional technology]

As shown in FIG. 2, for example, such a paint drying furnace heat-dries the painted object (A) in a furnace body (20) using convection hot air, and the paint drying furnace is equipped with a combustion device (30).
and air supply means (40).

The combustion device (30) is supplied with exhaust gas from the furnace containing a solvent gas generated as the coated article (A) in the furnace is heated and dried through a duct (26). The combustion device (30)
After the exhaust gas is incinerated at a predetermined temperature, it is discharged into the duct (32) as high-temperature combustion exhaust gas.

The high temperature combustion exhaust gas discharged from the combustion device (30) is supplied to the air supply means (40) including a heat exchanger (41).
supplied to In the air supply means (40), fresh air taken in from the outside air via the fresh air supply pipe (43) is heated by exchanging heat with the high temperature combustion exhaust gas. The heated fresh air is then supplied into the furnace.

In such a paint drying furnace, the amount of the exhaust gas that is incinerated by the combustion device (30) (hereinafter simply referred to as exhaust amount) and the amount of fresh air supplied to the furnace by the air supply means (40) are determined. (hereinafter simply referred to as replenishment amount) is equal to I, and whether the air volume supply and demand balance in the furnace can be maintained. Conventionally, the displacement amount and the replenishment amount are
A) was assumed to be constant regardless of changes in quantity.

And for temperature adjustment inside the furnace, the combustion device (30)
Adjust the amount of heat exchange between the high-temperature combustion exhaust gas from the outside and the fresh air taken in from the outside air (specifically,
41) by adjusting the amount of fresh air bypassed by the bypass damper (42)), the temperature inside the furnace can be adjusted to suit the drying of the painted objects, regardless of changes in the quantity of painted objects (A) (i.e., fluctuations in the load inside the furnace). I tried to keep it at a certain temperature.

In other words, in the paint drying furnace, the combustion device (30
) has to be maintained at a predetermined temperature. Therefore, under the condition that the exhaust volume and the replenishment amount are constant, the high temperature combustion exhaust gas is By adjusting the amount of heat exchange between the fresh air and the fresh air (the amount of heat given to the fresh air from the high-temperature combustion exhaust gas), the amount of heat supplied to the furnace was adjusted, and the temperature inside the furnace was maintained at an appropriate temperature. .

[Problem to be solved by the invention]

In such a conventional paint drying oven, the displacement is constant and the combustion temperature of the combustion device (30) is also constant, so the amount of heat retained in the high-temperature combustion exhaust gas from the combustion device (3o) is always constant. Become. Therefore, when the number of coated objects (A) in the furnace is small and the amount of heat exchange between the high-temperature combustion exhaust gas and the fresh air is adjusted to a small amount, the coating material (A) is removed from the system without contributing to the heating of the fresh air. There has been a problem in that the heat retained in the high-temperature combustion exhaust gas that is disposed of (hereinafter referred to as the amount of heat disposed of outside the system) increases, resulting in a large energy loss.

The present invention has been made in view of the above circumstances, and provides a coating that can solve the above-mentioned energy saving problems while ensuring stable operation of the paint drying oven and appropriately incinerating the solvent gas etc. in the exhaust gas. The purpose is to provide a drying oven.

[Means to solve the problem]

The first characteristic configuration of the paint drying furnace according to the present invention is that exhaust air containing solvent gas generated when a painted object inside the furnace is heated and dried by convection hot air is supplied, and the exhaust air is combusted and incinerated. a combustion device for discharging as high-temperature combustion exhaust gas from the combustion device, and an air supply means for replenishing the convective hot air with fresh air heated by exchanging heat with the high-temperature combustion exhaust gas from the combustion device to maintain the temperature inside the furnace. A drying oven, comprising control means for controlling the amount of exhaust air supplied to the combustion device and the amount of fresh air supplied to the convective hot air by the air supply means according to the number of coated objects in the oven. The purpose is to be prepared, and its functions and effects are as follows.

[For production]

According to this characteristic configuration, the control means can perform control such that as the number of coated objects in the furnace decreases, the first two exhaust volumes and the replenishment volume are decreased in synchronization with each other.

When such control is performed, the combustion temperature of the combustion equipment is kept constant during incineration processing, but it is reduced according to the amount of exhaust gas or the number of coated materials in the furnace, so that the high temperature from the combustion equipment is reduced. Since the amount of heat held by the combustion exhaust gas itself will decrease as the number of coated objects decreases, the amount of heat supplied to the furnace will be reduced in order to maintain the temperature inside the furnace at an appropriate temperature in response to the decrease in the load inside the furnace. However, it is possible to reduce the amount of heat supplied into the system while effectively avoiding an increase in the amount of heat discarded outside the system.

It goes without saying that the air volume supply and demand balance within the furnace is maintained by synchronized reduction of the displacement amount and the replenishment amount.

〔Effect of the invention〕

Thus, according to the present invention, by maintaining the air volume supply and demand balance within the paint drying furnace, the paint drying furnace can be operated stably, and the combustion temperature of the combustion device can be maintained at a predetermined temperature. This makes it possible to appropriately incinerate solvent gases etc. in the exhaust gas while effectively avoiding energy loss when the coating material in the furnace decreases, making the intended energy savings by using exhaust gas in the paint drying furnace even more effective. will be achieved.

[Second characteristic configuration of the present invention] A second characteristic configuration of the paint drying furnace according to the present invention is such that the combustion temperature of the combustion device in a state where the painted object is not present in the furnace body is set to a temperature suitable for the incineration process. temperature setting means for lowering the combustion temperature of the combustion device from the predetermined temperature to a level that does not interfere with maintaining the temperature in the furnace, and returning the combustion temperature of the combustion device to the predetermined temperature when the painted object is brought into the furnace or in a state expected. It is in the fact that

When using a paint drying oven having such a characteristic configuration, the combustion temperature of the combustion device, which is set at a high temperature and consumes a large amount of energy, is lowered to the above temperature when there is no painted object in the furnace body and the exhaust air does not come out. By means of the setting means, the temperature can be lowered from the predetermined temperature suitable for the incineration process under conditions that do not interfere with maintaining the temperature inside the furnace, resulting in an energy saving effect. Moreover, according to the temperature setting means, it is possible to return the combustion temperature of the combustion device to the predetermined temperature when the painted material is brought into the furnace, so that the paint drying furnace can continue to operate without any problem. I can do it.

〔Example〕

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

FIG. 1 shows an embodiment of a paint drying furnace according to the present invention, and (20) in the figure indicates a tunnel-shaped furnace body.

Inside the furnace body (20), a conveying device (25) for conveying the coated article (A) on a suspended support is installed from the furnace inlet (20a) to the furnace outlet (20a).
b). Then, while the coated article (A) is being conveyed into the furnace by the conveying device (25), the coated article (A) is subjected to a heating drying process.

Inside the furnace body (20), a temperature raising zone ( 21) and a constant temperature zone (22) in which the coated object (A) is maintained at a constant temperature by convection hot air. Note that the constant temperature zone (22) is further divided into two zones: a first constant temperature zone (23) and a second constant temperature zone (24).

The temperature increasing zone (21), the first constant temperature zone (23)
, a fan (21) is provided in the second constant temperature zone (24), respectively.
a), (23a), (24a) or both ends of the intermediately inserted ducts (21b), (23b), (24b) are connected to allow ventilation, and the fan (21a)
, (23a), (24a), a circulating air path (2LA) communicating with the zones (21), (23), (24) in the ducts (21b), (23b), (24b); (23A) and (24A) are generated. and the circulation air path (21A),
(23A) and (24A) are used as part of the path to circulate the convective hot air.

The furnace body (20) is provided with one end of a duct (26) for discharging exhaust gas containing solvent gas, tar components, etc. generated during heating and drying of the coated object (A) from the furnace body (20). is connected. The other end of the duct (26) is connected to the combustion device (30) via an exhaust gas preheating heat exchanger (31), and the duct (26) supplies exhaust gas to the combustion device (30). It is supposed to be done. The amount of exhaust gas supplied to the combustion device (30) through the duct (26) is controlled by a fan (26a) interposed in the duct (26). The combustion device (30) burns the exhaust gas supplied via the duct (26) to incinerate harmful components such as solvent gas and tar components in the exhaust gas.

A duct (32) for discharging high-temperature combustion exhaust gas generated therefrom is drawn out from the combustion device (30), and the duct (32) is connected to the exhaust preheating heat exchanger (
31). The high-temperature combustion exhaust gas discharged through the duct (32) is used as a heat source for the exhaust gas in the exhaust gas preheating heat exchanger (31). In addition, the duct (3
2) The amount of high temperature combustion exhaust gas discharged from the duct (32
) is controlled by a fan (32a) that is intermediately installed in the fan (32a).

The duct (32) is connected to the exhaust preheating heat exchanger (31).
) The piping is arranged to extend further downstream than the location. The piping of the duct (32) also passes through a fresh air heating heat exchanger (41), which is part of the air supply means (40), in its downstream region.

A fresh air supply pipe (43) for guiding a part of fresh air taken in from the outside air is also connected to the fresh air heating heat exchanger (41) which passes through the duct (32) midway. It has become. In the heat exchanger (41), heat exchange is performed between the high temperature combustion exhaust gas and the fresh outside air. The heated fresh air heated by the heat exchange is mixed in an appropriate amount with the outside air fresh air that passes through the bypass damper (42) whose flow rate can be freely controlled without passing through the heat exchanger (41). The mixed fresh air has an appropriate temperature suitable for maintaining a predetermined temperature inside the body (20). Then, the mixed fresh air is supplied to the furnace body (2).
0), more specifically, each zone (21).

(23), (24) and a circulating air passage (21A),
(23A) and (24A). and,
The temperature inside the furnace is maintained at a predetermined temperature for each zone by being supplemented with convective hot air within the furnace body (20). Note that the amount of fresh air supplied by the fresh air supply pipe (43) is determined by the amount of fresh air supplied by the fresh air supply pipe (43).
This is done under the control of a).

Now, the furnace body (20) is provided with sensors (11) and (12) at its furnace inlet (20a) and furnace outlet (20b) for detecting passage of the coated object (A), The detection signals of the sensors (11) and (12) are transmitted to the furnace body (
20) control for controlling the amount of exhaust air supplied to the combustion device (30) and the amount of fresh air supplied to the convective hot air by the air supply means (40) according to the number of coated objects (A) in the interior; A control device (10
).

The control device (1O) receives input from the sensor (11
), the number of coated objects (A) in the furnace body (20) is calculated using the detection signals of (12), and based on the calculation result, the combustion device! An appropriate amount of exhaust air to be supplied to the exhaust air duct (26) and an appropriate amount of fresh air to be supplied to the convection hot air by the air supply means (40) are determined, and based on the results, an appropriate amount of fresh air to be supplied to the exhaust air duct (26) is determined. ), a fan (32a) installed halfway in the high-temperature combustion exhaust gas duct (32), and a fan (32a) installed halfway in the fresh air supply pipe (43). (i.e., as the number of coated objects (A) in the furnace body (20) decreases, the combustion device (
Amount of exhaust air supplied to 30) and air supply means (40)
control to reduce the amount of fresh air supplied in synchronization with each other.

[Another embodiment] The control device (10) receives input from the sensor (11).
), the number of coated objects (A) in the furnace body (20) is calculated using the detection signals of (12), and when the number is zero, the combustion temperature of the combustion device (30) is calculated as described above. Lowering the temperature from a predetermined temperature suitable for incineration to a level that does not interfere with maintaining the temperature inside the furnace, and also lowering the combustion temperature of the combustion device (30) when the painted object (A) is expected to be brought into the furnace. An embodiment may also be considered in which the temperature setting means (50) functions to return the temperature to the predetermined temperature. Incidentally, the combustion device t
The combustion temperature of the combustion device (30) is adjusted by adjusting the combustion temperature of the combustion device (30).
0) by adjusting the burner (30a) provided.

In addition, in order to anticipate the conveyance of the painted object (A) into the furnace, for example, a sensor (not shown) that detects the passage of the painted object (A) is installed in the conveyance device for the painted object (A) to the coating drying furnace. may be provided, and the delivery into the furnace may be predicted based on the detection result of the sensor.Also, the coating schedule for the object to be coated (A) may be inputted into the control device (10) in advance, and the control device may be configured to control the process based on the information. It is also possible to anticipate the delivery into the furnace.

Further, as a means for detecting the quantity of coated objects (A) in the furnace body (20), the furnace inlet (20a) of the furnace body (20) is used.
and a sensor (II) for detecting passage of the coated object (A) installed at the furnace outlet (20b). For example, the furnace body (20)
From the detection result of the sensor (II) installed at the furnace inlet (20a) and the conveyance speed of the coated object (A) in the furnace, the quantity of coating*(A) in the furnace body (20) is determined. Alternatively, a method may be considered in which the quantity of coated objects (A) in the furnace body (2o) at each point in time is determined based on a preset drying treatment schedule.

It should be noted that the present invention is not limited to the structure shown in the accompanying drawings by adding reference numerals in the claims for convenient comparison with the drawings.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an embodiment of a paint drying oven according to the present invention, and FIG. 2 is an overall configuration diagram showing a conventional paint drying oven. (10)... Control means, (2o)...
Furnace body, (3o)... group/combustion device, (4o)...
・Air supply means, (5o) ・Old temperature setting means, (A
)...Painted object.

Claims (1)

[Claims] 1. Exhaust air containing solvent gas generated when the coated article (A) in the furnace body (20) is heated and dried by convection hot air is supplied, and the exhaust air is combusted and incinerated. A combustion device (30) is provided to discharge the heated combustion exhaust gas as high-temperature combustion exhaust gas, and fresh air heated by exchanging heat with the high-temperature combustion exhaust gas from the combustion device (30) is supplied to the convection hot air in order to maintain the temperature inside the furnace. A paint drying furnace equipped with an air supply means (40) for controlling the amount of exhaust air supplied to the combustion device (30) and the air supply means according to the number of coated objects (A) in the furnace. Control means (10) for controlling the amount of fresh air supplied to the convection hot air according to (40)
A paint drying oven equipped with 2. The combustion temperature of the combustion device (30) in a state where the painted material (A) is not present in the furnace body (20) is changed from a predetermined temperature suitable for the incineration process to a temperature that interferes with maintaining the temperature inside the furnace. The method further comprises a temperature setting means (50) which lowers the combustion temperature of the combustion device (30) to the predetermined temperature in a state in which the painted object (A) is expected to be carried into the furnace. The paint drying oven according to item 1.