Hot air generation device

Abstract

To provide a hot air generation device capable of decreasing a carbon dioxide discharge amount.SOLUTION: The hot air generation device for carrying out heat treatment relating to dry gas of a coating drying furnace, comprises: a heating chamber to which the dry gas is supplied; and an electric flow heater attached to a wall of the heating chamber, wherein the electric flow heater comprises: a heating unit provided with a heating element; an introduction unit provided outside the heating chamber to introduce gas flowing through the heating unit; a discharge unit provided in the heating chamber to discharge gas flowing through the heating unit; and an electric connection terminal provided outside the heating chamber to supply the heating element with electric power.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hot air generating device. [Background technology]

[0002] In paint drying ovens used to dry paint on automobiles and the like, hot air generating devices such as a hot air circulation device for heating the drying gas circulated in the paint drying oven and a heat treatment device for removing tar when the drying gas is exhausted into the atmosphere are provided (for example, Patent Document 1). Gas burners are widely used as the heat source for such hot air generating devices. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3251157 Summary of the Invention [Problem to be solved by the invention]

[0004] To prevent global warming, the industrial sector is being asked to reduce carbon dioxide emissions. It is desirable to use a heat source that emits less carbon dioxide as an alternative to gas burners.

[0005] An object of the present invention is to provide a hot air generator capable of reducing carbon dioxide emissions. [Means for solving the problem]

[0006] According to the present invention, A hot air generating device for performing heating treatment on drying gas of a paint drying oven, a heating chamber to which the drying gas is supplied; an electric flow heater attached to a wall of the heating chamber; The electric flow heater is A heating unit provided with a heating element; an introduction section provided outside the heating chamber and through which a gas passing through the heating section is introduced; an exhaust section provided inside the heating chamber, through which gas that has passed through the heating section is exhausted; an electrical connection terminal provided outside the heating chamber for supplying power to the heating element; Equipped with A hot air generating device is provided. Effect of the Invention

[0007] According to the present invention, a hot air generator capable of reducing carbon dioxide emissions can be provided. [Brief description of the drawings]

[0008] [Figure 1] Schematic diagram of a paint drying system. [Diagram 2] FIG. 2 is a diagram showing a configuration in the vicinity of an electric flow heater. [Diagram 3] 3(A) is a cross-sectional view of an electric flow heater, and (B) is a cross-sectional view along line AA in FIG. 3(A) and a partially enlarged view. [Figure 4] 1A is a diagram showing the configuration in the vicinity of another electric flow heater, and FIG. 1B is a cross-sectional view of another electric flow heater. [Diagram 5] 4A and 4B are flowcharts showing an example of processing by a control device. [Figure 6] 4A and 4B are flowcharts showing an example of processing by a control device. [Figure 7] Schematic diagram of another paint drying system. [Figure 8] FIG. 11 is a diagram showing another example of the support. [Figure 9] FIG. 13 is a diagram showing another example of a heat treatment apparatus. [Figure 10] Schematic diagram of a paint drying system using a gas burner. [Figure 11] FIG. 13 is an explanatory diagram showing an example of replacing a gas burner with an electric flow heater. [Figure 12] FIG. 13 is an explanatory diagram showing an example of replacing a gas burner with an electric flow heater. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] First Embodiment <Paint drying system> FIG. 1 is a schematic diagram of a paint drying system 1. The paint drying system 1 is a system that performs a baking and drying process of a coating film on a workpiece W. In this example, the workpiece W is assumed to be the body of an automobile. The paint drying system 1 includes a paint drying oven 2, a plurality of hot air circulating devices 3, a heat treatment device 5, and a control device 6. The paint drying oven 2 has an inlet 20a and an outlet 20b for the workpiece W, and has a cylindrical wall body 20 that forms a drying space between them. The workpiece W is transported by a transport device 23 from the inlet 20a to pass through the outlet 20b, during which the coating film on the workpiece W is dried. The hot air circulating device 3 and the heat treatment device 5 are both examples of hot air generating devices that generate hot air.

[0011] The hot air circulation device 3 is a supply device that supplies high-temperature drying gas to the paint drying oven 2, and in this embodiment, two hot air circulation devices 3 are provided. In this embodiment, the drying gas is heated air. Three or more hot air circulation devices 3 may be provided. The hot air circulation device 3 includes a heating chamber 30 and a circulation section RC that circulates the drying gas between the heating chamber 30 and the paint drying oven 2.

[0012] The circulation section RC supplies the dry gas in the paint drying oven 2 to the heating chamber 30 via an air passage 31a communicating with the paint drying oven 2. An electric flow heater 33 is provided in the heating chamber 30 as a heat source. The electric flow heater 33 heats fresh outside air FS blown by a fan 34, and the heated fresh outside air is blown into the heating chamber 30. The fan 34 takes in fresh outside air FS via an air passage 34a and blows it to the electric flow heater 33. A filter 35 is provided in the air passage 34a, and the filter 35 removes foreign matter such as dust from the fresh outside air FS.

[0013] The inside of the heating chamber 30 is divided into an upstream space and a downstream space by a filter 36. Drying gas is blown into the upstream space from the paint drying oven 2, and heated fresh outside air FS is introduced from an electric flow heater 33. The drying gas and the fresh outside air FS are mixed together to generate high-temperature drying gas.

[0014] The circulation section RC is equipped with a fan 32, and the drying gas from which foreign matter has been removed by the filter 36 is returned by the fan 32 to the paint drying oven 2 via an air passage 32a communicating with the paint drying oven 2. The returned drying gas is blown into the paint drying oven 2 from a plurality of nozzles provided in the paint drying oven 2 to dry the coating on the workpieces W. In this way, the drying gas is circulated between the paint drying oven 2 and the hot air circulation device 3, and is heated by the hot air circulation device 3, thereby making it possible to maintain the drying gas in the paint drying oven 2 at a predetermined temperature.

[0015] The heat treatment device 5 is a regenerative deodorizing device that burns and detoxifies harmful substances in the dry gas and exhausts them. Examples of harmful substances include VOCs (volatile organic compounds) and tar. The heat treatment device 5 detoxifies harmful substances by heating and oxidizing them.

[0016] The heat treatment device 5 includes a heating chamber 50. Dry gas is supplied to the heating chamber 50 by a fan 51 through an air passage 51a. The dry gas is introduced into the fan 51 through an air passage 41, fans 42 and 43, and an air passage 44. The fan 42 takes in dry gas from a hood portion 21 provided at the entrance 20a, and sends the gas to the fan 51 through the air passage 44. The fan 43 takes in dry gas from a hood portion 22 provided at the exit 20b, and sends the gas to the fan 51 through the air passage 44.

[0017] The heating chamber 50 is provided with an electric flow heater 53 as a heat source. The electric flow heater 53 heats the gas blown by the fan 54, and the heated gas is blown into the drying chamber 50. The gas blown by the fan 54 may be fresh outside air, but in this embodiment, dry gas is used. Specifically, dry gas is supplied from the fan 51 to the fan 54 via the air passage 51b branched from the air passage 51a, and the dry gas is blown from the fan 54 to the electric flow heater 53. By using dry gas as the gas supplied to the electric flow heater 53, it is possible to promote the combustion and detoxification of harmful substances in the dry gas, and by using dry gas that has already been heated, it is possible to increase the temperature in the heating chamber 50 with less energy.

[0018] The inside of the heating chamber 50 is divided into a lower space and an upper space by a catalyst 55. A part of the dry gas is blown into the lower space by a fan 51. The dry gas heated by an electric flow heater 53 is introduced into the upper space. A part of the dry gas blown from the fan 51 is heated by the dry gas heated by the electric flow heater 53, and passes through the catalyst 55 to be rendered harmless. The rendered harmless dry gas is released into the atmosphere by a fan 52.

[0019] The control device 6 is an electronic circuit that controls the entire paint drying system 1. The control device 6 includes, for example, a processor such as a CPU, a storage device such as a semiconductor memory, an input / output interface for inputting and outputting signals to and from external devices, a communication interface for communicating with a higher-level device, an input device for accepting operations from an operator, and a display device for displaying information to the operator, and the processor executes a program stored in the storage device to control each actuator that constitutes the paint drying system 1. The higher-level device is, for example, a computer that supervises the entire painting facility including the paint drying system 1.

[0020] <Electric flow heater> The electric flow heater 33 will be described with reference to Fig. 2 to Fig. 3(B). Fig. 2 is a diagram showing the configuration in the vicinity of the electric flow heater 33. Fig. 3(A) is a cross-sectional view of the electric flow heater 33, which corresponds to the cross-sectional view taken along line A'-A' in Fig. 3(B). Fig. 3(B) is a cross-sectional view taken along line AA in Fig. 3(A) and a partially enlarged view thereof.

[0021] Electric flow heater 33 has an overall axial or cylindrical appearance extending in the D1 direction, and is equipped with gas (fresh outside air FS) inlet 331 at one end in the D1 direction and exhaust 332 for exhausting heated gas at the other end. Inlet 331 is located outside heating chamber 30, and fan 34 is connected to inlet 331 via air passage 34b. Because inlet 331 is located outside heating chamber 30, the installation and piping work for fan 34 and air passage 34b is easy.

[0022] The electric flow heater 33 includes a metal case member 330 that constitutes the outer wall of the electric flow heater 33. The case member 330 has a hollow cylindrical shape as a whole, and a disk-shaped flange portion 333 that protrudes radially from the case member 330 is integrally formed at a midpoint in the D1 direction. The electric flow heater 33 is fixed to a wall portion 300 that constitutes the outer wall of the heating chamber 30 by the flange portion 333. More specifically, a cylindrical mounting portion 301 is formed in the wall portion 300, and a flange portion 301a having the same shape as the flange portion 333 is provided in the mounting portion 301. A plurality of mounting holes 333a are formed in the flange portion 333 in the circumferential direction, and the flange portion 333 and the flange portion 301a are fixed by fastening with bolts and nuts. When the electric flow heater 33 is fixed to the wall portion 300, the discharge portion 332 is located in the internal space 302 of the heating chamber 30.

[0023] One end of the case member 330 is closed by an end plate 330d. The end plate 330d is formed with the above-mentioned introduction portion 331. The introduction portion 331 has a cylindrical shape that communicates with the inside of the case member 330.

[0024] A heating unit HP1 is built into the case member 330. The heating unit HP1 is located in the internal space 302 of the heating chamber 30. The heating unit HP1 includes a plurality of heating elements 338 and a support 337 that supports the heating elements 338. The heating elements 338 are wires that generate heat when electricity is applied, such as nichrome wires or kanthal wires. In the illustrated example, three heating elements 338 are used. The support 337 is a cylindrical member in which a large number of holes 337a are formed, penetrating in the D1 direction. The support 337 is made of, for example, a ceramic material.

[0025] The holes 337a form air passages and also function as support holes for the heating elements 338. Each heating element 338 passes through one hole 337a, then turns back, passes through another hole 337a, turns back again, and passes through yet another hole 337a. In this way, the heating elements 338 pass through the multiple holes 337a, reciprocating through the support 337 in the direction D1. The gas passing through the holes 337a can be heated by generating heat from the heating elements 338. If the support 337 is made of a ceramic material, the gas can be heated to a higher temperature by emitting far infrared rays, for example, heating to 1000 degrees Celsius or more is possible.

[0026] On the peripheral wall of the case member 33, there are provided electrical connection terminals 334 corresponding to the heating elements 338, and an electrical connection terminal 335 at GND potential. The electrical connection terminals 334 and 335 are arranged between the end plate 330d and the flange portion 333. One end of the heating element 338 is connected to the corresponding electrical connection terminal 334, and the other end is connected to the electrical connection terminal 335. Wiring of a drive circuit is connected to the electrical connection terminals 334 and 335, and the current supply is controlled by the control device 6. The electrical connection terminals 334 and 335 are located outside the heating chamber 30 and exposed to the outside of the case member. This improves the workability of wiring work and electrical system maintenance work.

[0027] A heat insulating material 339 is provided around the heating part HP1. The heat insulating material 339 is formed, for example, by wrapping a strip-shaped heat insulating material around the heating part HP1, or has a cylindrical shape that covers the heating part HP1. The heat insulating material 339 is, for example, ceramic fiber. By providing the heat insulating material 339 around the heating part HP1, the heating part HP1 can be insulated from the internal space 302 of the heating chamber 30, and the effect of the temperature of the internal space 302 on the heating part HP1 can be reduced.

[0028] Deterioration of the insulating material 339 due to use may cause the insulating material 339 to become a source of dust. Since the drying gas heated by the hot air circulation device 3 is returned to the paint drying furnace 2, it is undesirable for the drying gas to contain dust. In this embodiment, the case member 33 has a cover part CP that covers the insulating material 339.

[0029] The cover part CP is formed on the heating chamber 30 side from the flange part 333, and is formed integrally with the flange part 333. The cover part CP has an outer tube part 330a, an end plate part 330b, and a nozzle part 332. The outer tube part 330a has a cylindrical shape and covers the peripheral surface of the heat insulating material 339. The end plate part 330b closes the end part (the end part of the case member 33) of the outer tube part 330a and covers the end part of the heat insulating material 339. The nozzle part 332 is formed on the end plate part 330b, is a cylindrical member constituting the discharge part 332, and faces the end part of the heating part HP1. The opening area of ​​the nozzle part 332 is slightly smaller than that of the end part of the heating part HP1. Since the heat insulating material 339 is covered by the cover part CP, even if dust is generated, it can be suppressed from flowing out to the outside.

[0030] 3(A), fresh outside air FS introduced into the inside of the case member 33 from the introduction part 331 by the fan 34 is heated by passing through the heating part HP1, and is blown out from the exhaust part 332 into the internal space 302 of the heating chamber 30. The temperature of the heated fresh outside air FS can be controlled by the air volume of the fan 34 and the power to the heating element 338.

[0031] An example of sensors used to control the hot air circulator 3 will be described. A temperature sensor 38 and a pressure sensor 39A are provided in the heating chamber 30. An air volume sensor 37 and a pressure sensor 39B are provided in the air passage 34b. A temperature sensor 336 is provided in the electric flow heater 33.

[0032] Temperature sensor 38 can detect the temperature of the gas that has passed through electric flow heater 33, and the temperature inside heating chamber 30 (temperature adjustment of the drying gas) can be adjusted by controlling the air volume of fan 34 and the power supplied to heating element 338 based on this detection result. The detection results of pressure sensors 39A and 39B can detect the pressure loss of the gas passing through electric flow heater 33. If the pressure loss is large, it can be determined that the resistance to the passage of gas in heating part HP1 is high, in other words, that clogging has occurred due to deterioration from use, and this can be used as a guide for replacement or maintenance of support 338.

[0033] The air volume of the fan 34 can be detected by the air volume sensor 37, and the fan 34 can be controlled based on the detection result. The detection result of the air volume sensor 37 can also be used as a guide for replacement or maintenance of the support 338. That is, if the detection result of the air volume sensor 37 indicates an extremely low air volume compared to the output of the fan 34, it can be determined that the resistance to the passage of gas in the heating part HP1 is high, that is, that clogging has occurred due to deterioration from use. The temperature sensor 336 is a sensor that detects the temperature of the heating part HP1, and the temperature detection part 336a is disposed inside the support 337. Based on the detection result of the temperature sensor 336, it is possible to perform temperature control of the heating part HP1, estimate a disconnection of the heating element 338 (the temperature is low compared to the amount of current flow), etc.

[0034] Next, electric flow heater 53 will be described with reference to Figures 4(A) and 4(B). The basic configuration of electric flow heater 53 is the same as electric flow heater 33, and the following description will focus on the differences. Figure 4(A) is a diagram showing the configuration in the vicinity of electric flow heater 53. Figure 4(B) is a cross-sectional view of electric flow heater 33, and corresponds to the cross-sectional view of Figure 3(A) used to explain electric flow heater 33.

[0035] The electric flow heater 53 has an overall axial or cylindrical appearance extending in the D11 direction, and is provided with an inlet 531 for dry gas at one end in the D11 direction and an outlet 532 for discharging heated gas at the other end. The inlet 531 is located outside the heating chamber 50, and a fan 54 is connected to the inlet 531 via an air passage 54a.

[0036] The electric flow heater 53 includes a metal case member 530 that constitutes the outer wall of the electric flow heater 53. The case member 530 has a hollow cylindrical shape as a whole, and a disk-shaped flange portion 533 that protrudes radially from the case member 530 is integrally formed at a midpoint in the D11 direction. The electric flow heater 53 is fixed to a wall portion 500 that constitutes the outer wall of the heating chamber 50 by the flange portion 533. More specifically, a cylindrical mounting portion 501 is formed in the wall portion 500, and a flange portion 501a having the same shape as the flange portion 533 is provided in the mounting portion 501. A plurality of mounting holes 533a are formed in the flange portion 533 in the circumferential direction, and the flange portion 533 and the flange portion 501a are fixed by fastening with bolts and nuts. When the electric flow heater 53 is fixed to the wall portion 500, the discharge portion 532 is located in the internal space 502 of the heating chamber 50.

[0037] One end of the case member 530 is closed by an end plate 530b. The end plate 530b is formed with the above-mentioned introduction portion 531. The introduction portion 531 has a cylindrical shape that communicates with the inside of the case member 530.

[0038] Heating part HP2 is built into case member 330. Heating part HP2 has a structure similar to that of heating part HP1, and includes a plurality of heating elements 538 and a support body 537 that supports heating elements 538. Heating elements 538 and support body 537 are similar to heating elements 338 and support body 337 of electric flow heater 33. On the peripheral wall of case member 53, electrical connection terminals 534 corresponding to each heating element 538 and an electrical connection terminal 535 that is at GND potential are provided.

[0039] The case member 530 has a tubular portion 537 that supports the heating part HP2. The tubular portion 537 is a cylindrical member that extends in the direction D11 from the flange portion 533 toward the heating chamber 50, and the end portion forms the discharge part 532.

[0040] A heat insulating material 539 is provided around the heating part HP2. The heat insulating material 539 is a member similar to the heat insulating material 339 of the electric flow heater 33, and is formed, for example, by wrapping a strip-shaped heat insulating material around the tube part 537, or has a cylindrical shape surrounding the tube part 537.

[0041] Although the insulation material 539 may become a source of dust due to deterioration of the insulation material 539 with use, the drying gas heated by the heat treatment device 5 is exhausted without being returned to the paint drying furnace 2. For this reason, unlike the electric flow heater 33, the electric flow heater 53 does not have a member for covering the insulation material 539. However, it goes without saying that the electric flow heater 53 may have the same structure as the electric flow heater 33 having the cover part CP.

[0042] 4(B), the dry gas introduced into the inside of the case member 53 from the introduction part 531 by the fan 54 is heated by passing through the heating part HP2, and is blown out from the exhaust part 532 into the internal space 502 of the heating chamber 50. The temperature of the heated dry gas can be controlled by the air volume of the fan 54 and the power to the heating element 538.

[0043] A description will be given of examples of sensors used to control the heat treatment device 5. In the case of this embodiment, the heat treatment device 5 is provided with sensors similar to those of the hot air circulation device 3, a temperature sensor 58 and a pressure sensor 59A are provided in the heating chamber 50, an air volume sensor 57 and a pressure sensor 59B are provided in the air passage 54a, and a temperature sensor 536 having a temperature detection unit 536a provided on a support 537 is provided in the electric flow heater 53.

[0044] The methods of using the detection results of the temperature sensor 58, pressure sensors 59A and 59B, air volume sensor 57, and temperature sensor 536 are similar to those of the temperature sensor 38, pressure sensors 39A and 39B, air volume sensor 37, and temperature sensor 336 of the hot air circulating device 3.

[0045] In this embodiment, the electric flow heaters 33 and 53 are used as the heat sources of the hot air circulation device 3 and the heat treatment device 5. The use of the electric flow heaters 33 and 53 can reduce carbon dioxide emissions and contribute to the prevention of global warming. The use of the electric flow heaters 33 and 53 as the heat sources allows for a small-scale and simple installation compared to, for example, duct electric heaters, and further allows for the use of equipment similar to that of an existing paint drying system using a gas burner as a heat source, so there is a high cost advantage. The heating parts HP1 and HP2 are disposed inside the heating chambers 30 and 50, which are in a high-temperature environment, so that the power required for heat generation can be reduced. In addition, the electrical connection terminals 334, 335, 534, and 535 and the introduction parts 331 and 531 are disposed outside the heating chambers 30 and 50, so that the workability of electrical wiring and the workability of piping the air passage can be improved.

[0046] <Example of control device processing> An example of control of the electric flow heater 33 and the like by the control device 6 will be described below. Each control example shown below is executed periodically. Fig. 5(A) is a flow chart showing an example of such control, which shows an example of control for maintaining the temperature of the gas blown out from the electric flow heater 33 (the temperature inside the heating chamber 30) within a target temperature range.

[0047] In step S1, the detection result of the temperature sensor 38 is obtained. In step S2, it is determined whether the temperature detection result obtained in step S1 exceeds a predetermined upper limit value, and if it exceeds the upper limit value, the process proceeds to step S3, and if it does not exceed the upper limit value, the process proceeds to step S4.

[0048] In step S3, the power supplied to heating element 338 is reduced. In step S4, it is determined whether the temperature detection result acquired in step S1 is below a predetermined lower limit, and if it is below, the process proceeds to step S5, and if it is not below, the process ends. In step S5, the power supplied to heating element 338 is increased. By the above processing, the temperature of the gas blown out from electric flow heater 33 (the temperature inside heating chamber 30) can be maintained within the target temperature range.

[0049] 5(B) shows an example of control related to abnormality judgment of heating part HP1. In step S11, the detection result of temperature sensor 336 is acquired. In step S12, it is judged whether the temperature detection result acquired in step S11 exceeds a predetermined upper limit value, and if it exceeds the upper limit value, the process proceeds to step S14, and if it does not exceed the upper limit value, the process proceeds to step S13. If the temperature detection result exceeds the upper limit value, it is assumed that heating part HP1 is generating abnormal heat, and error processing is performed in step S14.

[0050] In step S13, it is determined whether the temperature detection result acquired in step S11 is below a predetermined lower limit value, and if it is below, the process proceeds to step S14, and if it is not below, the process ends. If the temperature detection result exceeds the upper limit value, it is assumed that the current value cannot be controlled, and error processing is performed in step S14. If the temperature detection result is below the lower limit value, it is assumed that the heating element is disconnected, and error processing is performed in step S14. Examples of error processing in step S14 include notifying an operator of the occurrence of an abnormality, notifying a higher-level device of the occurrence of an abnormality, and stopping operation of the hot air circulating device 3.

[0051] Next, FIG. 6(A) shows a processing example in which the power consumption of the hot air circulation device 3 is changed in response to the operating status of the system. When the number of works W per unit time is small, the amount of drying gas supplied to the paint drying oven 2 may be small. On the other hand, it is necessary to prevent the temperature of the drying gas from decreasing. Therefore, in this embodiment, the air volume of the fans 31, 32, and 34 is reduced, and the heat generation amount of the heating element 338 is also reduced. Since the temperature of the drying gas increases due to the reduction in the air volume, the heat generation amount of the heating element 338 is reduced by that amount, so that the heating temperature of the drying gas remains the same, but the air volume can be reduced. For example, when the temperature is 1000 degrees Celsius and the air volume is 100 CHM under normal conditions, when the operating rate is set to 50%, the air volume is set to 50 CHM, while the power supplied to the heating element 338 is also reduced by half (assuming that the heat generation amount is proportional to the power supply). This makes it possible to halve the air volume while maintaining the temperature of the drying gas at 1000 degrees Celsius.

[0052] The process of Fig. 6(A) will be described. In step S21, information (operation information) indicating the operation rate of the paint drying system 1 is acquired. The operation information is acquired, for example, from a higher-level device. In step S22, it is determined whether the operation rate acquired in step S21 is below a threshold value, and if it is determined that it is below a threshold value, the process proceeds to step S24, and if it is determined that it is not below a threshold value, the process proceeds to step S23.

[0053] In step S23, normal operation is continued. In step S24, control is switched to energy saving operation. In energy saving operation, the airflow of fans 31, 32, and 34 and the power supplied to heating element 338 are reduced compared to normal operation, and the circulation amount is reduced while maintaining the temperature of the drying gas at the same level as in normal operation. This ends the process. With this control, power consumption can be adjusted according to the system operation rate.

[0054] Next, FIG. 6(B) shows an example of processing related to determining whether or not to replace or perform maintenance on the heating part HP1. In step S31, the detection results of the pressure sensors 39A and 39B are obtained. In step S32, the pressure loss before and after the heating part HP1 is calculated from the detection results obtained in step S31. In step S33, it is determined whether or not the pressure loss calculated in step S32 exceeds a threshold value. If it does, the process proceeds to step S34, and if it does not, the process ends. If the pressure loss exceeds the threshold value, it is estimated that the support 337 is clogged, and that it is near the time to replace or perform maintenance on the heating part HP1. In step S34, the operator is notified to perform maintenance on the heating part HP1. This ends the process.

[0055] In this manner, in this embodiment, the hot air circulating device 3 can be controlled by utilizing the detection results of the temperature sensor 38, the pressure sensors 39A and 39B, and the temperature sensor 336. As for the control of the heat treatment device 5, the processes in Figs. 5(A) to 6(B) can be performed by utilizing the detection results of the temperature sensor 58, the pressure sensors 59A and 59B, and the temperature sensor 536.

[0056] Second Embodiment In the first embodiment, fresh outside air FS is supplied from the fan 34 to the electric flow heater 33, but dry gas may also be supplied. Fig. 7 shows one example. In the example shown, dry gas blown from the fan 31 is supplied to the fan 34 via the air passage 31b and the filter 35, and the dry gas is supplied from the fan 34 to the electric flow heater 33. Since the dry gas has a higher temperature than the fresh outside air FS, it is possible to reduce the amount of power supplied to the heating element 338 of the electric flow heater 33, and therefore the power consumption of the hot air circulating device 3 can be reduced.

[0057] <Third embodiment> The heating part HP1 may be composed of a plurality of pairs of support 337 and heating element 338. When clogging or disconnection occurs in a part of the heating part HP1, it can be dealt with by partial replacement. FIG. 8 shows an example. The support 337 shown in the figure is divided into four equal parts in the circumferential direction and is composed of support 337A to 337D. Each of the support 337A to 337D is a column member having a sector-shaped cross section and extending in the axial direction (D1 direction). The heating elements 338A to 338D correspond to the support 337A to 337D, and four electrical connection terminals 334A to 334D are provided corresponding to the heating elements 338A to 338D. Although the electrical connection terminal 335 set to the GND potential is shared as one, four may be provided corresponding to the heating elements 338A to 338D.

[0058] According to this embodiment, even if a problem occurs with the support 337A or the heating element 338A, the other supports 337B-337D and heating elements 338B-338D can continue to heat the gas, and by replacing the set of support 337A and heating element 338A with a new one, the other supports 337B-337D and heating elements 338B-338D can continue to be used, improving the cost advantage. Note that although the heating part HP1 has been described here, the same applies to the heating part HP2.

[0059] <Fourth embodiment> A plurality of independently operated electric flow heaters 33 may be attached to one heating chamber 30. Fig. 9 shows one example. In the illustrated example, three electric flow heaters 33 are fixed to one heating chamber 30. Three mounting portions 301 are provided on the wall portion 300 of the heating chamber 30, and an electric flow heater 33 is fixed to each mounting portion 301.

[0060] By providing a plurality of electric flow heaters 33 in the heating chamber 30 and driving them independently in this way, it becomes possible to control the operation by, for example, driving all three electric flow heaters 33, stopping one and driving the remaining two electric flow heaters 33, or driving only one electric flow heater 33. This makes it possible to adjust the amount of drying gas circulated, or to continue operating the system even if some of the electric flow heaters 33 fail.

[0061] In the illustrated example, a fan 34 is assigned to each electric flow heater 33, but it is also possible to share one fan 34. It is also possible to provide a plurality of electric flow heaters 53 that are driven independently for the heating chamber 50.

[0062] <Fifth embodiment> It is also possible to replace an existing paint drying system using a gas burner as a heat source with an electric flow heater to make it an electrified system. Figure 10 shows an existing paint drying system 1' using a gas burner 100 as a heat source, and has the same configuration as the paint drying system 1 in Figure 1, except that the heat source is the gas burner 100. Fuel gas FG is supplied to the gas burner 100 by a supply facility 7.

[0063] FIG. 11 shows a method of replacing the heat source, and in particular, shows a schematic example of replacing the heat source of the hot air circulation device 3. The gas burner 100 has a flange portion 104 to be attached to the mounting portion 301 of the heating chamber 30, and also has an inlet portion 103 for the fuel gas FG and an inlet portion 110 for the fresh outside air FS. The gas burner 100 is removed from the mounting portion 301, and the electric flow heater 33 is attached to the mounting portion 301. The method of replacing the heat source of the heat treatment device 5 is similar. By removing the fuel gas FG supply equipment 7 and adding an electric power supply equipment for the heating element 338, the existing hot air circulation device 3 and heat treatment device 5 that used the gas burner 100 as a heat source can be replaced with an electrified heat treatment device. As a result, a system similar to the paint drying system 1 shown in FIG. 1 is obtained. That is, by replacing the existing paint drying system 1' using the gas burner 100 as a heat source with the electric flow heaters 33, 53 which have a relatively similar configuration, electrification can be achieved relatively easily.

[0064] When it is dimensionally difficult to attach the electric flow heater 33 to the mounting portion 301 of the heating chamber 30 to which the gas burner 100 was attached, an adapter may be used for attachment. FIG. 12 shows an example. The adapter 310 has a cylindrical shape and has a flange portion 311 at one end and a flange portion 312 at the other end. The flange portion 311 has dimensions that fit the mounting portion 301, and the flange portion 312 has dimensions that fit the flange portion 333 of the electric flow heater 33. The electric flow heater 33 can be fixed to the heating chamber 30 by fastening the flange portion 311 to the mounting portion 301 and fastening the flange portion 312 to the flange portion 333. The electric flow heater 53 can also be attached to the heating chamber 50 via an adapter in the same manner.

[0065] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]

[0066] 3 Hot air circulation device (hot air generator), 5 Heat treatment device (hot air generator), 33 Electric flow heater, 53 Electric flow heater

Claims

1. A hot air generating device for performing heating treatment on drying gas of a paint drying oven, a heating chamber to which the drying gas is supplied; an electric flow heater attached to a wall of the heating chamber; The electric flow heater is A heating unit provided with a heating element; an introduction section provided outside the heating chamber and through which a gas passing through the heating section is introduced; an exhaust section provided inside the heating chamber, through which gas that has passed through the heating section is exhausted; an electrical connection terminal provided outside the heating chamber for supplying power to the heating element; Equipped with A hot air generating device characterized by:

2. The hot air generating device according to claim 1, The heating unit includes a ceramic support having a through hole formed therein, The heating element is provided in the through hole, and a gas is passed through the through hole. A hot air generating device characterized by:

3. The hot air generating device according to claim 1, The electric flow heater is A heat insulating material provided inside the heating chamber and provided around the heating unit; A metal cover portion is provided inside the heating chamber and covers the heat insulating material. A hot air generating device characterized by:

4. The hot air generating device according to claim 3, The cover portion is An outer cylinder portion; an end plate portion covering an end portion of the outer tubular portion; A cylindrical nozzle portion formed in the end plate portion and constituting the discharge portion, A hot air generating device characterized by:

5. The hot air generating device according to claim 3 or claim 4, The electric flow heater is a flange portion formed integrally with the cover portion and configured to fix the electric flow heater to the wall portion; A hot air generating device characterized by:

6. The hot air generating device according to claim 1, The hot air generating device is a hot air circulating device having a circulation section that returns the drying gas heated in the heating chamber to the paint drying furnace. A hot air generating device characterized by:

7. The hot air generating device according to claim 1, The dry gas is introduced into the introduction part. A hot air generating device characterized by:

8. The hot air generating device according to claim 7, The hot air generator is a heat treatment device that burns and detoxifies harmful substances in the dry gas and exhausts the gas. A hot air generating device characterized by:

9. The hot air generating device according to claim 1, A detection means for detecting a pressure loss of a gas passing through the electric flow heater is provided. A hot air generating device characterized by:

10. The hot air generating device according to claim 1, A detection means is provided for detecting the temperature of the gas that has passed through the electric flow heater. A hot air generating device characterized by:

11. The hot air generating device according to claim 1, A detection means for detecting the amount of gas passing through the electric flow heater is provided. A hot air generating device characterized by:

12. The hot air generating device according to claim 1, A fan for supplying gas to the introduction portion; a control unit for controlling the fan and the power supplied to the heating element; The control means executing a process of transitioning the control state from a first control state to a second control state in which the air volume of the fan and the power are reduced compared to those in the first control state; A hot air generating device characterized by:

13. The hot air generating device according to claim 1, A plurality of the electric flow heaters are provided on the wall, the electric flow heaters being independently driven. A hot air generating device characterized by:

14. The hot air generating device according to claim 1, The heating unit includes a plurality of sets of the heating element and a ceramic support body that supports the heating element. A hot air generating device characterized by:

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