JP4003186B2 - Drying system for painting - Google Patents

Description

  The present invention relates to a coating drying system, and more particularly to a coating drying furnace for drying a painted surface of an automobile body or the like in a drying furnace body.

  When an automobile body or the like is painted, the body is then guided to a drying furnace for drying the painted surface. That is, the drying furnace has a tunnel shape, and the painted automobile body is continuously transferred by the conveyor, for example. During this transfer, radiant heat is radiated from the radiant panel to the painted surface of the automobile body, or hot air is blown onto the painted surface, whereby the painted surface is heated and dried (see, for example, Patent Documents 1 and 2).

  Conventionally, what is called a “one burner system” is known as a system for supplying heat to a radiant panel or a hot air supply duct. FIG. 4 is a schematic configuration diagram for explaining the system. As shown in the figure, the coating drying furnace 101 is composed of a radiation heating zone 102 on the front stage side and a convection heating zone 103 on the rear stage side. In the 1 burner system, the combustion heat generated in the direct combustion device 105 is supplied to the radiation panel 106 in the radiation heating zone 102 and the hot air supply duct 107 in the convection heating zone 103. More specifically, the odorless gas that is burned and heated in the direct combustion device 105 is led out through the main supply passage 111. In the middle of the main supply passage 111, a lead-out fan 112 is provided, and a plurality of circulation branch passages 113, 114, 115 are provided so as to correspond to the zones 102, 103, respectively. The heat generated from the main supply passage 111 is transmitted to the radiant panel 106 and the hot air supply duct 107 via the heat exchangers 116, 117, and 118 provided in the circulation branch passages 113 to 115. The

  On the other hand, the exhaust heating gas sucked in the exhaust duct 121 provided in the radiant heating zone 103 passes through the main return passage 122 together with the outside air taken in from the outside of the drying furnace 101 to the direct combustion device 105. Returned. That is, an introduction fan 123 is provided in the middle of the main return passage 122, and the operation of the introduction fan 123 causes a mixed gas of exhaust gas and outside air to flow through the main return passage 122 at a constant flow rate to the direct combustion device 123. Is returned.

In such a one-burner method, since only one direct combustion device needs to be provided, the advantage is that production facilities can be simplified and costs can be reduced as compared with the case where a plurality of combustion devices are provided. There is.
JP-A-11-156275 Japanese Patent Laid-Open No. 7-103650

  By the way, under the above configuration, for the convenience that it is necessary to cover the heating of the plurality of zones 102 and 103 with one direct combustion device 105, the flow rate of the gas in the main return passage 123 returned to the direct combustion device 105, and The flow rate of the heated gas in the main supply passage 111 led out from the direct combustion device 105 is required to be equivalent (for example, 300 normal cubic meters / minute). Therefore, conventionally, the odorless gas that flows through the main supply passage 111 and is provided downstream of the circulation branch passages 116 to 118 is discharged to the outside with the corresponding flow velocity.

  Here, if the painted car body to be dried is efficiently transported without being divided, it is unlikely to be a problem. In such a case, there is a risk that the amount of odorless gas discharged becomes too large in the above-described one-burner method. For this reason, the energy required to dry one unit becomes extremely large, and as a result, there is a risk of wasting energy and increasing costs.

  Therefore, in the present invention, not only can the complexity of equipment be suppressed, but also the waste of energy can be suppressed even when the number of workpieces to be dried is small, energy saving and cost reduction can be achieved. The technical challenge is to provide a paint drying system that can be

  In the following, each means suitable for solving the above-described problems will be described in terms of items. In addition, the effect etc. peculiar to the means to respond | correspond as needed are added.

Means 1. A tunnel-shaped drying furnace having a plurality of drying zones and configured to convey a painted workpiece inside; a single direct combustion device for generating a heated gas by combustion; The heated gas generated in the direct combustion device is transported, and based on the heat of the heated gas, configured to be able to supply heat to each of the drying zones, and finally a supply passage capable of discharging the heated gas to the outside Of each drying zone, provided in at least one of a return passage for returning the gas recovered from at least one drying zone to the direct combustion apparatus, and the supply passage and the return passage, in the supply passage and the return passage In a coating drying system comprising a fan capable of forming a gas flow,
The coating drying system, wherein the supply passage and the return passage are communicated with each other through a circulation passage, and a part of the heated gas flowing through the supply passage is circulated to the direct combustion device.

  According to the means 1, since heat is provided to each zone of the drying furnace based on the heat of the heated gas generated in a single direct combustion device, the complexity of equipment and the complexity of control can be suppressed. In addition, the supply passage and the return passage are communicated with each other through the circulation passage, and a part of the heated gas flowing through the supply passage is circulated to the direct combustion device, so that the heated gas finally discharged from the supply passage The amount can be reduced. In other words, the heated gas passing through the supply passage can be recycled by recirculating it to the direct combustion device. Therefore, the amount of outside air introduced from the outside can be reduced, and the amount of fuel required in the direct combustion device can be reduced. As a result, waste of energy can be suppressed, and energy saving and cost reduction can be achieved.

Mean 2. A tunnel-shaped drying furnace having a plurality of drying zones and configured to convey a painted workpiece inside; a single direct combustion device for generating a heated gas by combustion; Heat is supplied to each of the drying zones based on the main supply passage through which the heated gas generated in the direct combustion device is transported and finally discharged to the outside, and the heat of the heated gas flowing through the main supply passage. A branch passage configured to be possible, a return passage for returning gas recovered from at least one of the drying zones to the direct combustion apparatus, and at least one of the supply passage and the return passage A drying system for coating comprising a fan capable of forming a gas flow in the supply passage and the return passage,
The main supply passage downstream of the branch passage and the return passage are communicated with each other through a circulation passage, and a part of the heated gas flowing through the supply passage is circulated to the direct combustion device. Drying system for painting.

  According to the means 2, since heat is brought to each zone of the drying furnace based on the heat of the heated gas generated in a single direct combustion device, the complexity of equipment and the complexity of control can be suppressed. In addition, the main supply passage and the return passage are communicated with each other through the circulation passage, and a part of the heated gas flowing through the main supply passage is recirculated to the direct combustion device, so that it is finally discharged from the main supply passage. The amount of heated gas can be reduced. In other words, the heated gas that has passed through the main supply passage that has been discharged to the outside can be reused by recirculating it to the direct combustion device. Therefore, the amount of outside air introduced from the outside can be reduced, and the amount of fuel required in the direct combustion device can be reduced. As a result, waste of energy can be suppressed, and energy saving and cost reduction can be achieved.

  Means 3. The branch passage is a circulation branch passage branched from the main supply passage and connected to the main supply passage, and a heat exchanger is provided in the middle of the circulation branch passage, and each of the branch passages is provided via the heat exchanger. The coating drying system according to means 2, characterized in that heat can be supplied to the drying zone.

  According to the means 3, the branch passage for supplying heat to each drying zone is constituted by a circulation branch passage branched from the main supply passage and connected to the main supply passage. And heat is supplied to each drying zone via the heat exchanger provided in the middle of this circulation branch passage. For this reason, compared with the case where heated gas is directly supplied to each drying zone, it is easier to adjust the temperature in each drying zone, and the flow rate of the heated gas flowing through the main supply passage can be stabilized.

  Means 4. The plurality of drying zones include a radiant heating zone having a radiant panel capable of radiating radiant heat, and a convection heating zone having a hot air supply duct capable of blowing hot air, and the return passage is from the convection heating zone. 4. The coating drying system according to any one of means 1 to 3, wherein the recovered gas is configured to return to the direct combustion device.

  According to the means 4, a single direct combustion device can provide heat for a radiant heating zone having a radiant panel capable of radiating radiant heat and a convection heating zone having a hot air supply duct capable of blowing hot air. it can. Further, since the gas recovered from the convection heating zone is returned to the direct combustion device via the return passage, the organic compound generated in the convection heating zone can be burned, and the organic compound gas is led out to the outside. It is possible to eliminate environmental problems caused by this.

  Means 5. The fan is provided in both the supply passage and the return passage, and the circulation passage connects the downstream side of the fan provided in the supply passage and the upstream side of the fan provided in the return passage. The coating drying system according to any one of means 1 to 4, wherein the drying system is for coating.

  According to the means 5, the heated gas flowing in the supply passage is actively flown toward the circulation passage, and the heated gas guided from the circulation passage to the return passage is actively directed toward the direct combustion device. It can flow. For this reason, the function of the circulation passage can be efficiently exhibited.

  Means 6. The coating drying system according to any one of means 1 to 5, wherein 30 to 80% of the heated gas flowing through the supply passage is recirculated to the direct combustion device. .

  If the ring flow rate of the heated gas is not more than the above lower limit (30%), the effect of this system may not be exhibited sufficiently. Further, if the ring flow rate is equal to or higher than the above upper limit (80%), incomplete combustion may occur due to oxygen shortage or the like in the direct combustion device. Note that the lower limit value may be set to 40% or 50%, and the upper limit value may be set to 70% or 60%.

  Mean 7 In the coating drying system according to any one of means 1 to 5, the workpiece is an automobile body.

  Hereinafter, an embodiment will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a coating drying system in the present embodiment. As shown in the figure, in the present embodiment, the automobile body 2 as a workpiece that has undergone the painting process is continuously transferred by a conveyor 3 (see FIG. 2 and the like), toward the entrance of the coating drying furnace 1. And is led out from the exit (right side of the figure). Further, the coating drying furnace 1 in the present embodiment is constituted by a radiation heating zone 4 on the front stage side and two convection heating zones 5A and 5B on the rear stage side.

  As shown in FIG. 2, the radiant heating zone 4 includes a tunnel-shaped furnace body 11 and a pair of radiation panels provided on both sides of the furnace body 11 along the transfer direction of the automobile body 2 (conveyor 3). 12. Each radiation panel 12 is configured to be able to radiate radiant heat toward the inside (the automobile body 2). And the vehicle body 2 which passed through the painting process passes the said radiation heating zone 4, and the solvent component contained in a coating film is mainly evaporated now. In the present embodiment, a predetermined hot air is circulated in a closed loop with respect to the radiation panel 12.

  Further, as shown in FIG. 3, the convection heating zones 5A and 5B are provided on both sides of the tunnel-type furnace main bodies 21A and 21B and the transfer directions of the automobile body 2 (conveyor 3) in the furnace main bodies 21A and 21B. A pair of hot air supply ducts 22A and 22B provided in the air and exhaust ducts 23A and 23B provided above the hot air supply ducts 22A and 22B.

  Predetermined heated air is supplied to the hot air supply ducts 22A and 22B. The hot air supply ducts 22 </ b> A and 22 </ b> B are provided with a plurality of outlets 25 facing the automobile body 2. Accordingly, the supplied heated air becomes hot air and is blown onto the coating surface from the blower outlet 25, whereby the coating film is baked and dried.

  The exhaust ducts 23A and 23B are provided with a plurality of discharge ports 27. From the exhaust port 27, contaminated air (exhaust gas) containing a solvent component generated in the furnace main bodies 21A and 21B is sucked.

  Next, the structure of the heat circulation including the heat supply to the radiation panel 12 and the hot air supply ducts 22A and 22B will be described. As shown in FIG. 1, in this embodiment, the combustion heat generated by the direct combustion device 31 is supplied to the radiation panel 12 and the hot air supply ducts 22A and 22B. More specifically, the odorless gas burned in the direct combustion device 31 and heated to 730 to 750 ° C. is led out through the main supply passage 32. A derivation fan 33 is provided in the middle of the main supply passage 32, and the operation of the derivation fan 33 causes heated odorless gas of 460 to 520 ° C. to flow through the main supply passage 32 at a constant flow rate.

  In the middle of the main supply passage 32, a first circulation branch passage 34, a second circulation branch passage 35, and a third circulation branch passage are provided so as to correspond to the radiation heating zone 4 and the convection heating zones 5A and 5B. 36 is provided.

  The first circulation branch passage 34 corresponds to the radiation heating zone 4, and the first circulation branch passage 34 and the main supply passage 32 in the vicinity of the branch portion are provided with flow rate adjusting valves 37 and 38, respectively. The opening degree of the valves 37 and 38 is adjusted based on the surface temperature of the radiation panel 12 detected separately.

  A heat exchanger 39 is provided in the middle of the first circulation branch passage 34, and the circulation gas in the panel circulation path 41 that circulates the radiation panel 12 is heated in the heat exchanger 39. Yes. More specifically, a fan 42 is provided in the panel circulation path 41 immediately downstream of the heat exchanger 39, and the circulation gas heated to about 260 ° C. in the heat exchanger 39 by the fan 42 is radiated from the radiation panel. 12 is supplied. Then, the circulating gas at about 200 ° C. that has circulated through the radiation panel 12 is returned to the heat exchanger 39 where it is heated.

  The second and third circulation branch passages 35 and 36 correspond to the convection heating zones 5A and 5B, respectively, and the second circulation branch passage 35 and the main supply passage 32 in the vicinity of each branch portion, and the third The circulation branch passage 36 and the main supply passage 32 are provided with flow rate adjusting valves 43, 44 and 45, 46, respectively. The valves 43, 44, 45, and 46 are adjusted in opening degree based on the hot air temperature of the hot air supply ducts 22A and 22B that is separately detected.

  Heat exchangers 47 and 48 are also provided in the middle of the second and third circulation branch passages 35 and 36, and are supplied to the hot air supply ducts 22A and 22B in the heat exchangers 47 and 48, respectively. The gas is heated. More specifically, fans 53 and 54 are provided in the duct circulation paths 51 and 52 immediately downstream of the heat exchangers 47 and 48, respectively. Heated air heated to 140 to 170 ° C. is supplied to the hot air supply ducts 22A and 22B. A mixed gas of a part of the exhaust gas sucked in the exhaust ducts 23A and 23B and the outside air introduced through the filters 55 and 56 and the valves 57 and 58 is heated in the heat exchangers 47 and 48. It has become so. In the present embodiment, the main supply passage 32 and the first to third circulation branch passages 35 to 37 constitute a supply passage.

  Meanwhile, the remaining exhaust gas heated by the exhaust ducts 23 </ b> A and 23 </ b> B is returned to the direct combustion device 31 through the main return passage 61. That is, an introduction fan 62 is provided in the middle of the main return passage 61, and exhaust gas of about 140 to 170 ° C. flows through the main return passage 61 at a constant flow rate by the operation of the introduction fan 62, and the direct combustion device 31. Returned to.

  Now, under such a configuration, the flow rate of the exhaust gas in the main return passage 61 returned to the direct combustion device 31 for the convenience of heating the three zones 4, 5A, 5B with one direct combustion device 31, In addition, the flow rate of the heated gas in the main supply passage 32 led out from the direct combustion device 31 needs to be equivalent (for example, 300 normal cubic meters / minute). In this regard, in the present embodiment, the circulation passage 71 is provided so that the downstream side of the outlet fan 33 of the main supply passage 32 and the upstream side of the introduction fan 62 of the main return passage 61 communicate with each other. In addition, flow control valves 73 and 74 are provided in the circulation passage 71 and the main supply passage 32 in the vicinity of the branch portion of the main supply passage 32, respectively, so that the flow rate of the gas flowing through both the passages 71 and 32 is adjusted appropriately. It has become.

  Next, the effect of this embodiment comprised as mentioned above is demonstrated.

  As described above, the automobile body 2 is guided toward the inlet portion of the coating drying furnace 1 while being continuously transferred by the conveyor 3, and is led out from the outlet portion. During this transfer, the automobile body 2 passes through the radiant heating zone 4 and the two convection heating zones 5A, 5B, and is heated in the zones 4, 5A, 5B, and the coating film is dried.

  In the present embodiment, since heat is provided to the zones 4, 5A, 5B of the drying furnace 1 based on the heat of the heated odorless gas generated in the single direct combustion device 31, the equipment is complicated and controlled. Can be prevented from becoming complicated.

  In addition, the main supply passage 32 and the main return passage 61 are communicated with each other through the circulation passage 71, and a part of the heated gas (for example, 300 normal cubic meters / minute) flows through the main supply passage 32 (for example, 300 normal cubic meters / minute). 180 normal cubic meters / minute) is recirculated to the direct combustion device 31. For this reason, the amount of the heated gas finally discharged from the main supply passage 32 can be reduced. For example, a heating gas of about 200 ° C. was conventionally discharged at 300 normal cubic meters / minute, whereas according to the present system, a heating gas of about 200 ° C. was discharged at 120 normal cubic meters / minute. Become.

  In other words, the heated gas passing through the main supply passage 32 that has been exhausted to the outside can be reused by recirculating it to the direct combustion device 31 again. Therefore, the amount of outside air introduced from the outside can be reduced. For example, in the past, a mixed gas of approximately normal temperature outside air introduced from the inlet / outlet of the drying furnace 1, valves 57, 58, and the like and return gas from the exhaust duct was introduced at 300 normal cubic meters / minute. On the other hand, according to the present system, the heated air at 200 ° C. is circulated 180 normal cubic meters / minute, so that the mixed gas of the introduced outside air and the return gas from the exhaust ducts 23A and 23B is 120 normal · Just about cubic meters / minute. As a result, the amount of fuel required in the direct combustion device 31 can be reduced. As a result, waste of energy can be suppressed, and significant energy saving and cost reduction can be achieved.

  In addition, it is not limited to the description content of the said embodiment, For example, you may implement as follows. Of course, other application examples and modification examples not illustrated below are also possible.

  (A) In the above embodiment, the main supply passage 61 is concretely used when a predetermined flow rate (for example, 300 normal cubic meters / minute) is recirculated at about 3/5 (60%) (for example, 180 normal cubic meters / minute). However, it is not limited to such figures. However, the amount to be circulated is preferably 30% or more and 80% or less of the heated gas flowing through the main supply passage 32. If the ring flow rate is equal to or lower than the lower limit (30%), the effect of the present system may not be sufficiently exhibited. Further, if the ring flow rate is equal to or higher than the upper limit value (80%), incomplete combustion may occur in the direct combustion device 31 due to lack of oxygen or the like. Note that the lower limit value may be set to 40% or 50%, and the upper limit value may be set to 70% or 60%.

  (B) In the above embodiment, the drying furnace 1 is composed of one radiant heating zone 4 and two convection heating zones 5A and 5B. However, a plurality of radiant heating zones may be provided, or a convection heating zone. May be composed of one or three or more. A plurality of any one type of zones may be provided.

  (C) In the above embodiment, the fans 33 and 62 are provided in the main supply passage 32 and the main return passage 61, respectively, but may be provided in only one of them.

  (D) In the above embodiment, the work to be dried is embodied in the automobile body 2, but may be applied to the case where the coating of another work is dried.

It is a mimetic diagram showing a schematic structure of a drying system for painting in one embodiment. It is a front view which shows schematic structure of a radiant heating zone. It is a rear view which shows schematic structure of a convection heating zone. It is a schematic block diagram which shows an example of the conventional drying system for coating.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drying furnace for coating, 2 ... Automobile body as a workpiece, 3 ... Conveyor, 4 ... Radiation heating zone, 5A, 5B ... Convection heating zone, 12 ... Radiation panel, 22A, 22B ... Hot air supply duct, 23A, 23B ... Exhaust duct, 31 ... direct combustion device, 32 ... main supply passage, 33 ... outlet fan, 34 ... first circulation branch passage, 35 ... second circulation branch passage, 36 ... third circulation branch passage, 39, 47 , 48 ... heat exchanger, 61 ... main return passage as return passage, 62 ... introduction fan, 71 ... recirculation passage.

Claims (5)

A tunnel-shaped drying furnace having a plurality of drying zones and configured to convey a painted workpiece inside;
A single direct combustion device for generating heated gas by combustion;
A heating gas generated in the direct combustion device is transported, based on the heat of the heating gas, configured to be able to supply heat to the drying zones, and finally, a supply passage capable of discharging the heating gas to the outside,
A return passage for returning the gas recovered from at least one of the drying zones to the direct combustion device;
In a coating drying system comprising a fan provided in at least one of the supply passage and the return passage and capable of forming a gas flow in the supply passage and the return passage,
The coating drying system, wherein the supply passage and the return passage are communicated with each other through a circulation passage, and a part of the heated gas flowing through the supply passage is circulated to the direct combustion device. A tunnel-shaped drying furnace having a plurality of drying zones and configured to convey a painted workpiece inside;
A single direct combustion device for generating heated gas by combustion;
A main supply passage through which the heated gas generated in the direct combustion device is transported and finally discharged to the outside;
A branch passage configured to supply heat to each of the drying zones based on the heat of the heated gas flowing through the main supply passage;
A return passage for returning the gas recovered from at least one of the drying zones to the direct combustion device;
In a coating drying system comprising a fan provided in at least one of the main supply passage and the return passage and capable of forming a gas flow in the supply passage and the return passage,
The main supply passage downstream of the branch passage and the return passage are communicated with each other through a circulation passage, and a part of the heated gas flowing through the supply passage is circulated to the direct combustion device. Drying system for painting.   The branch passage is a circulation branch passage branched from the main supply passage and connected to the main supply passage, and a heat exchanger is provided in the middle of the circulation branch passage, and each of the branch passages is provided via the heat exchanger. The coating drying system according to claim 2, wherein heat is supplied to the drying zone.   The plurality of drying zones include a radiant heating zone having a radiant panel capable of radiating radiant heat, and a convection heating zone having a hot air supply duct capable of blowing hot air, and the return passage is from the convection heating zone. 4. The coating drying system according to claim 1, wherein the recovered gas is returned to the direct combustion device.   The fan is provided in both the supply passage and the return passage, and the circulation passage connects the downstream side of the fan provided in the supply passage and the upstream side of the fan provided in the return passage. The coating drying system according to any one of claims 1 to 4, wherein the drying system is for coating.

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