Drying equipment and method for controlling VOC concentration in drying equipment

Abstract

To provide a drying facility capable of keeping a VOC concentration at a prescribed concentration without increasing its size and without making it complicated, and a method of controlling the VOC concentration.SOLUTION: A drying facility 10 according to an embodiment of the present invention, comprises: a combustion air introduction pipe 100 that comprises a blower 101 and a damper 102 and introduces air into a combustion device 50; a fuel introduction pipe 110 that comprises a flow control valve 111 and introduces fuel into the combustion device 50; a drying gas introduction pipe 130 that introduces drying gas into a drying furnace 20 from the combustion device 50; an exhaust pipe 140 that comprises an exhaust fan 142 and exhausts exhaust gas from the drying furnace 20; a VOC concentration detector 143 that detects the concentration of VOC contained in exhaust gas present in the exhaust pipe 140; a gas temperature detector 132 that detects the temperature of the drying gas; and a controller that controls the exhaust fan 142 and the blower 101 according to the signal detected by the VOC concentration detector 143 and controls the damper 102 and the flow control valve 111 according to the signal detected by the gas temperature detector 132.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a drying facility and a method for controlling a VOC concentration in the drying facility. [Background technology]

[0002] Conventional drying equipment includes a drying furnace that dries the material to be dried using drying gas generated by a heat source such as a combustion device, and a cooling furnace that cools the material to be dried in the drying furnace. In such drying equipment, a circulation type drying furnace that returns a part of the drying gas that has dried the material to be dried to the heat source is widely used as the drying furnace.

[0003] In such conventional drying equipment, a drying gas, which is hot air, is introduced into the drying oven, and a cooling gas, which is cold air, is introduced into the cooling oven. Therefore, in conventional drying equipment that uses a drying gas, which is hot air, and a cooling gas, which is cold air, equipment equipped with a heat pump has been considered in order to improve energy efficiency.

[0004] In a drying facility equipped with a heat pump, for example, air heated by obtaining heat in a condenser-side heat exchanger (heating-side heat exchanger) of the heat pump is introduced into a combustion device. The air introduced into the combustion device is used, for example, as dilution air for adjusting the temperature of the combustion gas, and as cooling air for cooling the combustion device. A mixture of the combustion gas and the dilution air is introduced into a drying furnace as drying gas. The combustion device also includes a supply pipe for combustion air used for combustion with fuel.

[0005] On the other hand, in a drying facility equipped with a heat pump, air that has been cooled by losing heat in an evaporator of the heat pump is introduced into a cooling furnace as cooling air.

[0006] Drying equipment equipped with a heat pump heats and cools a specified flow rate of air, although the flow rate varies depending on the outside air temperature, while maintaining the heat pump's coefficient of performance (COP) at its highest value.

[0007] In the drying furnace of such drying equipment, when the coating film on the coated object is dried, volatile organic compounds (hereinafter referred to as VOCs) contained in the coating film evaporate. If the VOC concentration in the drying furnace reaches a certain range, it may explode. Therefore, it is necessary to maintain the VOC concentration in the drying furnace at a certain value (e.g., 1 / 4 of the lower explosion limit) or less.

[0008] When the VOC concentration in the drying oven exceeds a predetermined value, it is necessary to reduce the VOC concentration. In such cases, the drying ovens of conventional drying equipment are equipped with a system that recovers and removes the VOCs contained in the circulating drying gas and circulates the drying gas to the drying oven. In conventional drying equipment, this VOC removal circulation system adjusts the VOC concentration in the drying oven to a predetermined value or less. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2010-51932 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, providing a VOC removal and circulation system as described above in a drying facility leads to an increase in size and complexity of the drying facility.

[0011] Furthermore, adding a VOC removal and circulation system as described above to existing drying equipment that does not have the function to remove VOCs would require large-scale expansion work and would lead to the drying equipment becoming larger and more complicated.

[0012] The problem that the present invention aims to solve is to provide drying equipment and a VOC concentration control method for drying equipment that can maintain the VOC concentration in a drying oven at a predetermined concentration without increasing the size or complexity. [Means for solving the problem]

[0013] The drying equipment of the embodiment includes a combustion device, an air supplying machine and an air flow rate adjusting unit, a combustion air introduction pipe for introducing combustion air into the combustion device, a fuel introduction pipe for introducing fuel into the combustion device, a dilution air introduction pipe for introducing dilution air into the combustion device, a heat pump having a heating heat exchanger for heating the dilution air flowing through the dilution air introduction pipe, a branch pipe branching from the combustion air introduction pipe between the air supplying machine and the air flow rate adjusting unit and connecting to the dilution air introduction pipe, a drying device for drying a material to be dried, and a mixed gas containing the combustion gas and dilution air generated in the combustion device and introduced to the drying device as a drying gas. the drying gas circulation piping that introduces the drying gas from the drying device to the dilution air introduction pipe and circulates it to the combustion device; a VOC concentration detector that detects the concentration of volatile organic compounds contained in the drying gas related to the drying gas in the drying device; a gas temperature detector that detects the temperature of the drying gas related to the drying gas in the drying device; and a control unit that controls the exhaust blower and the air supplier based on a detection signal from the VOC concentration detector, and controls the air flow rate adjustment unit and the fuel flow rate adjustment valve based on a detection signal from the gas temperature detector. Effect of the Invention

[0014] According to the drying equipment and the VOC concentration control method for drying equipment of the present invention, the VOC concentration in the drying furnace can be maintained at a predetermined concentration without increasing the size or complexity. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a schematic overview of a drying facility according to a first embodiment; [Diagram 2] 2 is a block diagram showing a configuration of a control unit that executes control for maintaining a VOC concentration in a VOC concentration detector at a VOC concentration threshold value in the drying equipment of the first embodiment. FIG. [Diagram 3] 4 is a flowchart for explaining an operation for maintaining a VOC concentration in exhaust gas at a VOC concentration threshold value in the drying equipment of the first embodiment. [Figure 4] 4 is a flowchart for illustrating the action of adjusting the temperature of the drying gas, which is one of the actions for maintaining the VOC concentration in the exhaust gas at the VOC concentration threshold value in the drying equipment of the first embodiment. [Diagram 5] FIG. 13 is a diagram illustrating an outline of a drying facility according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] (First embodiment) FIG. 1 is a diagram showing a schematic overview of a drying facility 10 according to the first embodiment.

[0018] As shown in Fig. 1, the drying facility 10 includes a drying furnace 20 and a cooling furnace 30. The drying furnace 20 functions as a drying device, and the cooling furnace 30 functions as a cooling device.

[0019] For example, the workpiece W, the surface of which has been painted in a painting section, is conveyed to the drying furnace 20. In the drying furnace 20, hot air from a drying gas is applied to the workpiece W, which is the object to be dried, to dry, for example, the paint applied to the surface of the workpiece W. During the drying process in the drying furnace 20, VOCs contained in the paint evaporate.

[0020] The workpiece W dried in the drying furnace 20 is transported to the cooling furnace 30. In the cooling furnace 30, the workpiece W dried in the drying furnace 20 is subjected to cold air for cooling, for example, to cool the workpiece W.

[0021] The workpiece W is transported in the drying furnace 20 and the cooling furnace 30 while being suspended from a wire or the like.

[0022] Although not shown, the drying furnace 20 is provided with, for example, an ejection nozzle that ejects drying gas onto the transported workpiece W. The temperature of the drying gas ejected onto the workpiece W is, for example, 60 to 200° C. The temperature of the drying gas is set appropriately depending on the specifications of the workpiece W.

[0023] Although not shown, the cooling furnace 30 is provided with, for example, an ejection nozzle that ejects cooling air onto the transported workpiece W. The temperature of the cooling air ejected onto the workpiece W is, for example, 15 to 30° C. The temperature of the cooling air is set appropriately depending on the specifications of the workpiece W.

[0024] As described above, the drying equipment 10 needs to generate the drying gas (hot air) to be introduced into the drying furnace 20 and the cooling air (cold air) to be introduced into the cooling furnace 30. Therefore, the drying equipment 10 is provided with a heat pump 40 capable of both releasing and absorbing heat. By providing the heat pump 40, the energy efficiency of the drying equipment 10 can be improved.

[0025] 1, the heat pump 40 includes a refrigerant flow path 41 through which a refrigerant flows as a heat medium. The refrigerant flow path 41 forms a ring-shaped circulation path. A condenser 42 (heat dissipation section), an evaporator 43 (heat absorption section), a compressor 44, and an expansion valve 45 are interposed in the refrigerant flow path 41.

[0026] The compressor 44 is disposed upstream of the condenser 42. In other words, the compressor 44 is disposed upstream of the condenser 42 and between the condenser 42 and the evaporator 43. The compressor 44 compresses the refrigerant flowing in the refrigerant flow path 41 and sends the refrigerant to the condenser 42.

[0027] The expansion valve 45 is disposed upstream of the evaporator 43. In other words, the expansion valve 45 is disposed upstream of the evaporator 43 and between the condenser 42 and the evaporator 43. The expansion valve 45 has a function of adjusting the refrigerant flow path 41 from a fully open state to a fully closed state. When the expansion valve 45 is not fully closed, the refrigerant is supplied to the evaporator 43.

[0028] In the heat pump 40 configured as above, the compressor 44 is driven with the expansion valve 45 closed, and the refrigerant is sent to the condenser 42. At this time, most of the flow of the refrigerant is stopped by the expansion valve 45. As a result, the refrigerant is compressed, and the temperature of the refrigerant near the condenser 42 increases.

[0029] On the other hand, as the refrigerant near the condenser 42 is compressed, the refrigerant near the evaporator 43 expands and becomes colder.

[0030] A dilution air introduction pipe 60 that introduces dilution air to the combustion device 50 is piped to the condenser 42. In other words, in the condenser 42, heat exchange occurs between the refrigerant flowing through the refrigerant passage 41 and the air flowing through the dilution air introduction pipe 60. As described above, when the compressor 44 is driven with the expansion valve 45 closed, the temperature of the refrigerant near the condenser 42 increases, and the dilution air is heated. The condenser 42 functions as a heating heat exchanger.

[0031] A part of an air cooling mechanism 70 that cools the air to be introduced into the cooling furnace 30 is piped to the evaporator 43. Specifically, a refrigerant circulation pipe 71 that circulates the refrigerant in the air cooling mechanism 70 is piped to the evaporator 43. In other words, in the evaporator 43, heat exchange occurs between the refrigerant flowing through the refrigerant passage 41 and the refrigerant flowing through the refrigerant circulation pipe 71.

[0032] As described above, when the compressor 44 is driven with the expansion valve 45 closed, the temperature of the refrigerant near the evaporator 43 drops, and the refrigerant flowing through the refrigerant circulation pipe 71 is cooled. The evaporator 43 functions as a refrigerant cooling heat exchanger that cools the refrigerant flowing through the refrigerant circulation pipe 71. Here, the refrigerant flowing through the refrigerant circulation pipe 71 is, for example, water.

[0033] The air cooling mechanism 70 also includes an air-cooling heat exchanger 72 that cools the cooling air flowing through the cooling air introduction pipe 80 with the refrigerant flowing through the refrigerant circulation pipe 71. The air cooling mechanism 70 also includes a circulation pump 73 that circulates the refrigerant. The circulation pump 73 is disposed in the refrigerant circulation pipe 71.

[0034] 1, the refrigerant circulation pipe 71 through which the refrigerant that has passed through the air-cooling heat exchanger 72 flows may be provided with a refrigerant heating heat exchanger 74 that heats the refrigerant flowing through the refrigerant circulation pipe 71. For example, a part of a branch exhaust pipe 145 branched off from an exhaust pipe 140 of the drying furnace 20 described later is arranged to pass through the refrigerant heating heat exchanger 74.

[0035] The branch exhaust pipe 145 is provided with a flow rate adjustment valve 146 for adjusting the flow rate of the exhaust gas flowing through the branch exhaust pipe 145 .

[0036] When the temperature of the refrigerant that has passed through the air-cooling heat exchanger 72 is lower than a predetermined temperature, the refrigerant flowing through the refrigerant circulation pipe 71 is heated in the refrigerant heating heat exchanger 74 by the exhaust gas flowing through the branch exhaust pipe 145. As a result, the refrigerant is circulated to the evaporator 43 at a predetermined temperature, and the heat pump 40 obtains a maximum cooling-side coefficient of performance (COP).

[0037] The cooling air introduction pipe 80 passes through the air-cooling heat exchanger 72 and is connected to the cooling furnace 30. In the air-cooling heat exchanger 72, heat exchange takes place between the refrigerant flowing through the refrigerant circulation pipe 71 and the air flowing through the cooling air introduction pipe 80. The air flowing through the cooling air introduction pipe 80 is cooled by the low-temperature refrigerant flowing through the refrigerant circulation pipe 71. This cooled air is introduced into the cooling furnace 30 as cooling air.

[0038] A fan 81 is disposed in the cooling air introduction pipe 80 to take in air from the outside into the cooling air introduction pipe 80 and introduce the cooling air into the cooling furnace 30. The fan 81 functions as a blower. For example, a blower may be used as the blower.

[0039] In addition, the cooling air that has cooled the workpiece W in the cooling furnace 30 is exhausted through a cooling air exhaust pipe 90. An exhaust fan 91 for exhausting the cooling air from the cooling furnace 30 into the atmosphere is interposed in the cooling air exhaust pipe 90.

[0040] Next, a configuration for introducing drying gas (hot air) into the drying furnace 20 will be described.

[0041] 1, the drying equipment 10 includes a combustion device 50, a combustion air introduction pipe 100, a fuel introduction pipe 110, a branch pipe 120, a dilution air introduction pipe 60, a drying gas introduction pipe 130, an exhaust pipe 140, and a drying gas circulation pipe 150. The drying equipment 10 also includes a control unit 160 that controls the drying equipment 10.

[0042] The combustion device 50 includes a combustion liner 51 that combusts fuel and air, and a casing 52 that houses the combustion liner 51. A gap 53 is defined between the combustion liner 51 and the casing 52.

[0043] The combustion air introduction pipe 100 introduces combustion air to the combustion device 50. Specifically, the combustion air introduction pipe 100 is connected to the combustion liner 51 and introduces air into the combustion liner 51. The combustion air introduction pipe 100 is equipped with a blower 101 that introduces outside air into the combustion air introduction pipe 100 and leads it to the combustion device 50. The blower 101 functions as an air supplier. For example, a fan may be used as the air supplier.

[0044] Further, a damper 102 is interposed in the combustion air introduction pipe 100. The damper 102 adjusts the flow rate of the combustion air introduced into the combustion liner 51. The damper 102 functions as an air flow rate adjustment unit. The air flow rate adjustment unit may be composed of, for example, a valve.

[0045] 1, a portion of the combustion air introduction pipe 100 is configured to be capable of exchanging heat with the drying gas flowing through the exhaust pipe 140. The drying gas flowing through the exhaust pipe 140 is the drying gas used to dry the workpieces W in the drying furnace 20 and then exhausted to the outside. Hereinafter, the drying gas flowing through the exhaust pipe 140 will be referred to as exhaust gas.

[0046] The combustion air introduction pipe 100 is arranged, for example, so as to pass through a heat exchanger 141 provided in an exhaust pipe 140. The air flowing through the combustion air introduction pipe 100 is heated by the exhaust gas through the heat exchanger 141.

[0047] The fuel introduction pipe 110 introduces fuel into the combustion device 50. Specifically, the fuel introduction pipe 110 is connected to the combustion liner 51, and introduces fuel from a fuel supply source (not shown) into the combustion liner 51. The fuel is not particularly limited, but for example, a hydrocarbon fuel is used.

[0048] A flow rate control valve 111 that adjusts the flow rate of fuel introduced into the combustion liner 51 is disposed in the fuel introduction pipe 110. A fuel flow meter 112 that measures the flow rate of fuel introduced into the combustion liner 51 is also disposed in the fuel introduction pipe 110. The flow rate control valve 111 is composed of a valve and the like. The flow rate control valve 111 functions as a fuel flow rate control valve.

[0049] The branch pipe 120 branches off from the combustion air introduction pipe 100 between the blower 101 and the damper 102, and is connected to the dilution air introduction pipe 60. Specifically, the branch pipe 120 branches off from the combustion air introduction pipe 100 downstream of the heat exchanger 141 and upstream of the damper 102.

[0050] The branch pipe 120 is connected to a dilution air introduction pipe 60 between the heat pump 40 and the combustion device 50. The branch pipe 120 is also provided with a damper 121 that adjusts the flow rate of air introduced to the dilution air introduction pipe 60. Note that a valve may be provided instead of the damper 121.

[0051] The air flowing through the branch pipe 120 functions as dilution air. The air flowing through the branch pipe 120 is introduced into the combustion device 50 together with the dilution air flowing through the dilution air introduction pipe 60.

[0052] As described above, the dilution air introduction pipe 60 introduces dilution air to the combustion device 50. Specifically, the dilution air introduction pipe 60 introduces dilution air, for example, to the gap 53 between the combustion liner 51 and the casing 52.

[0053] The dilution air introduced into the gap 53 flows downstream through the gap 53, mixes with the combustion gas discharged from the combustion liner 51, and flows into the drying gas introduction pipe 130. The dilution air flows into the combustion liner 51, for example, through a dilution hole formed in the combustion liner 51, and is discharged from the combustion liner 51 together with the combustion gas.

[0054] In this way, the dilution air mixes with the combustion gas discharged from the combustion liner 51 and the combustion gas inside the combustion liner 51 to dilute the combustion gas and adjust the temperature of the combustion gas to a predetermined temperature. This lowers the temperature of the combustion gas. Here, the predetermined temperature is the temperature required in the drying furnace 20.

[0055] In addition, the dilution air flowing downstream through the gap 53 also functions as a cooling medium for cooling the combustion liner 51 and the casing 52.

[0056] The air flowing through the dilution air introduction pipe 60 is heated in the condenser 42, which functions as a heating heat exchanger, by the refrigerant flowing through the refrigerant flow passage 41. The flow rate of the air flowing through the dilution air introduction pipe 60 is adjusted to a constant flow rate.

[0057] The dilution air introduction pipe 60 is provided with a fan 61 that introduces outside air into the dilution air introduction pipe 60 and guides it to the combustion device 50. The fan 61 is housed, for example, in the heat pump 40. The fan 61 functions as a blower. For example, a blower may be used as the blower.

[0058] The drying gas introduction pipe 130 introduces a mixed gas containing combustion gas generated by the combustion of fuel and combustion air in the combustion liner 51 and dilution air introduced from the dilution air introduction pipe 60 as drying gas from the combustion device 50 to the drying furnace 20. In other words, the drying gas introduction pipe 130 connects the combustion device 50 and the drying furnace 20. The mixed gas also includes the circulated drying gas introduced into the dilution air introduction pipe 60 via the drying gas circulation piping 150.

[0059] The drying gas introduction pipe 130 is provided with a fan 131 that introduces the drying gas discharged from the combustion device 50 into the drying furnace 20 and circulates the drying gas that has dried the workpieces W from the drying furnace 20 to the combustion device 50 via the drying gas circulation pipe 150. The fan 131 functions as an air blower. For example, a blower may be used as the air blower.

[0060] For example, the drying gas inlet pipe 130 is provided with a gas temperature detector 132 that detects the temperature of the drying gas flowing through the drying gas inlet pipe 130. In this case, the gas temperature detector 132 is provided in the drying gas inlet pipe 130. The gas temperature detector 132 is formed of, for example, a thermocouple.

[0061] Here, the gas temperature detector 132 detects the temperature of the drying gas related to the drying gas in the drying furnace 20. The drying gas related to the drying gas in the drying furnace 20 is a drying gas that can be regarded as the drying gas in the drying furnace 20.

[0062] Examples of the drying gas related to the drying gas in the drying furnace 20 include the drying gas in the drying furnace 20, the drying gas in the drying gas inlet pipe 130 described above, and the drying gas in the drying gas circulation pipe 150.

[0063] That is, the gas temperature detector 132 may be arranged in the drying furnace 20 so as to detect the temperature of the drying gas flowing through the drying gas inlet pipe 130 described above, or in the drying gas circulation pipe 150 so as to detect the temperature of the drying gas flowing through the drying gas circulation pipe 150.

[0064] Furthermore, the gas temperature detector 132 may be provided so as to detect the temperature of the drying gas at at least one of the locations in the drying gas introduction pipe 130, the drying furnace 20, and the drying gas circulation pipe 150. When the gas temperature detector 132 is provided at any of a plurality of these locations, each control is executed based on, for example, the temperature that is the largest difference from a gas temperature threshold value described later.

[0065] The drying gas circulation piping 150 introduces the drying gas from the drying furnace 20 to the dilution air introduction pipe 60. As a result, the drying gas introduced into the dilution air introduction pipe 60 via the drying gas circulation piping 150 is circulated to the combustion device 50.

[0066] Here, the drying gas circulated to the combustion device 50 is introduced again as drying gas into the drying furnace 20 via the drying gas introduction pipe 130. The drying gas flowing through the drying gas circulation pipe 150 is the drying gas used to dry the workpieces W in the drying furnace 20.

[0067] The drying gas circulation pipe 150 connects the drying furnace 20 to the dilution air introduction pipe 60 between the heat pump 40 and the combustion device 50 .

[0068] The drying gas circulation pipe 150 is connected to the dilution air introduction pipe 60, for example, on the heat pump 40 side of the position where the branch pipe 120 is connected to the dilution air introduction pipe 60. Note that the connection portion of the drying gas circulation pipe 150 to the dilution air introduction pipe 60 may be on the combustion device 50 side of the connection portion of the branch pipe 120 to the dilution air introduction pipe 60.

[0069] The exhaust pipe 140 exhausts the exhaust gas from the drying furnace 20 to the atmosphere. One end of the exhaust pipe 140 is connected to the drying furnace 20, and the other end of the exhaust pipe 140 is, for example, open to the atmosphere.

[0070] The exhaust pipe 140 is provided with an exhaust fan 142 for sucking in exhaust gas from the drying furnace 20 and discharging it to the atmosphere. The exhaust fan 142 functions as an exhaust blower. For example, a blower may be used as the exhaust blower.

[0071] As described above, the exhaust pipe 140 is provided with the heat exchanger 141. The air flowing through the combustion air introduction pipe 100 is heated by the exhaust gas flowing through the exhaust pipe 140 via the heat exchanger 141.

[0072] Furthermore, the exhaust pipe 140 is provided with a VOC concentration detector 143 that detects the concentration of VOCs contained in the exhaust gas flowing through the exhaust pipe 140. The VOC concentration detector 143 is provided in the exhaust pipe 140, for example, between the heat exchanger 141 and the drying furnace 20.

[0073] Here, the VOC concentration detector 143 detects the concentration of VOCs contained in the drying gas related to the drying gas in the drying oven 20. The drying gas related to the drying gas in the drying oven 20 is a drying gas that can be regarded as the drying gas in the drying oven 20.

[0074] Examples of the drying gas related to the drying gas in the drying furnace 20 include the drying gas in the exhaust pipe 140 and the drying gas in the drying gas circulation pipe 150, in addition to the drying gas in the drying furnace 20.

[0075] That is, the VOC concentration detector 143 may be arranged in the drying furnace 20 so as to detect the VOC concentration contained in the exhaust gas flowing through the exhaust pipe 140 described above, or in the drying gas circulation pipe 150 so as to detect the VOC concentration contained in the drying gas flowing through the drying gas circulation pipe 150.

[0076] Furthermore, the VOC concentration detector 143 may be provided so as to detect the VOC concentration contained in the drying gas (or exhaust gas) in at least one of the locations in the exhaust pipe 140, the drying furnace 20, and the drying gas circulation pipe 150. When the VOC concentration detector 143 is provided in a plurality of these locations, each control is executed based on the VOC concentration that has the largest difference from a VOC concentration threshold value described later, for example.

[0077] The VOC concentration detector 143 is configured with a detector that utilizes a measurement method such as, for example, FID (Flame Ionization) or catalytic oxidation-non-dispersive infrared absorption. Here, VOC is a general term for organic compounds that are volatile and turn into gas in the atmosphere, and VOCs include substances such as toluene, xylene, and ethyl acetate. Note that the VOC concentration detector 143 may be configured with, for example, a detector that detects a predetermined organic compound contained in the VOC. In this case, the VOC concentration threshold described later is appropriately set based on, for example, the allowable limit concentration of the predetermined organic compound.

[0078] The control unit 160 controls, for example, the exhaust fan 142 and the blower 101 based on a signal detected by the VOC concentration detector 143. The control unit 160 also controls, for example, the dampers 102 and 121 and the flow rate adjustment valve 111 based on a signal detected by the gas temperature detector 132.

[0079] FIG. 2 is a block diagram showing the configuration of the control unit 160 that executes control to maintain the VOC concentration in the VOC concentration detector 143 at the VOC concentration threshold value in the drying equipment 10 of the first embodiment.

[0080] As described above, examples of detection locations for the drying gas (including exhaust gas) in the VOC concentration detector 143 include inside the exhaust pipe 140, inside the drying furnace 20, and inside the drying gas circulation pipe 150. Here, an example is shown in which the detection location in the VOC concentration detector 143 is inside the exhaust pipe 140.

[0081] As shown in FIG. 2, the control unit 160 includes an input unit 170, a calculation unit 180, a storage unit 190, and an output unit 171.

[0082] The input unit 170 inputs detection signals from various detectors and flow meters. Specifically, the input unit 170 inputs detection signals from, for example, the VOC concentration detector 143, the gas temperature detector 132, the fuel flow meter 112, and the like.

[0083] The storage unit 190 is configured with a storage medium such as a read-only memory (ROM), a random access memory (RAM), etc. The storage unit 190 includes a threshold storage unit 191 and a flow rate correlation storage unit 192.

[0084] The threshold storage unit 191 provides a reference value for the judgment of each judgment unit and each setting unit of the calculation unit 180. The threshold storage unit 191 stores, for example, a VOC concentration threshold that serves as a reference value for a VOC concentration adjustment operation for maintaining the VOC concentration at a predetermined concentration. The VOC concentration threshold is set to ¼ of the lower explosion limit of the VOC gas. The lower explosion limit is the lowest concentration (minimum concentration) among the concentrations in the explosion range of the VOC gas.

[0085] By setting the VOC concentration threshold within the above range, the drying equipment 10 can be safely operated even when the detected VOC concentration fluctuates. Here, the VOC concentration threshold is not limited to the above range. The VOC concentration threshold can be appropriately set based on, for example, the specifications of the drying oven 20, the operating environment of the drying oven 20, etc.

[0086] In the VOC concentration adjustment operation, the detected VOC concentration is controlled to maintain the VOC concentration threshold. When the detected VOC concentration is higher or lower than the VOC concentration threshold, for example, the flow rate of the exhaust gas, the flow rate of the combustion air and the dilution air introduced into the combustion device 50, etc. are adjusted.

[0087] Furthermore, the threshold storage unit 191 stores, for example, a gas temperature threshold for the temperature of the drying gas introduced into the drying furnace 20. The gas temperature threshold can be set arbitrarily depending on, for example, the type of the workpiece W to be dried.

[0088] When the gas temperature detector 132 is arranged to detect the temperature of the drying gas in the drying furnace 20, the threshold memory unit 191 stores a gas temperature threshold for the temperature of the drying gas in the drying furnace 20. When the gas temperature detector 132 is arranged to detect the temperature of the drying gas flowing through the drying gas circulation piping 150, the threshold memory unit 191 stores a gas temperature threshold for the temperature of the circulated drying gas.

[0089] When the temperature of the drying gas introduced into the drying furnace 20 is higher than the gas temperature threshold value or lower than the gas temperature threshold value, for example, the flow rates of the combustion air, fuel, and dilution air introduced into the combustion device 50 are adjusted.

[0090] The flow rate correlation storage unit 192 provides reference values ​​for the determinations of the VOC concentration determination unit 181 and the temperature determination unit 182 of the calculation unit 180.

[0091] The flow rate correlation memory unit 192 stores, for example, an exhaust gas flow rate vs. VOC concentration correlation table for setting the flow rate of the exhaust gas to be discharged based on the difference between the VOC concentration in the exhaust gas detected by the VOC concentration detector 143 and a VOC concentration threshold value.

[0092] The flow rate of the exhaust gas to be discharged is determined by, for example, the rotation speed of the exhaust fan 142. Specifically, the exhaust gas flow rate vs. VOC concentration correlation table is configured with correlation data that determines the rotation speed of the exhaust fan 142 based on the difference between the VOC concentration in the exhaust gas detected by the VOC concentration detector 143 and the VOC concentration threshold value.

[0093] In addition, the flow rate correlation memory unit 192 stores, for example, an exhaust gas flow rate / air flow rate correlation table for introducing air at the same flow rate as the flow rate of the exhaust gas exhausted by the exhaust fan 142 from the blower 101 into the combustion air introduction pipe 100.

[0094] Specifically, the exhaust gas flow rate / air flow rate correlation table is made up of correlation data that defines the rotation speed of blower 101 for discharging air at the same flow rate as the exhausted exhaust gas flow rate. For example, the exhaust gas flow rate / air flow rate correlation table is made up of correlation data that defines the correspondence between the rotation speed of exhaust fan 142 and the rotation speed of blower 101.

[0095] Furthermore, the flow rate correlation storage unit 192 stores, for example, a fuel flow rate-air flow rate correlation table for setting the flow rate of combustion air based on the fuel flow rate.

[0096] In the combustion device 50, the air flow rate is adjusted to a predetermined ratio with respect to the fuel flow rate. In other words, in the combustion device 50, the air flow rate is adjusted to a predetermined air-fuel ratio or equivalence ratio with respect to the fuel flow rate. The fuel flow rate-air flow rate correlation table is composed of correlation data that defines the air flow rate corresponding to the fuel flow rate, for example.

[0097] The air flow rate is set based on data relating to the opening degree of the dampers 102 and 121 which is set according to the rotation speed of the blower 101, for example.

[0098] Furthermore, the flow rate correlation storage unit 192 stores, for example, a fuel flow rate-gas temperature correlation table for setting the fuel flow rate based on the difference between the temperature of the drying gas detected by the gas temperature detector 132 and the gas temperature threshold value.

[0099] The fuel flow rate-gas temperature correlation table is configured with correlation data that defines the fuel flow rate in proportion to the difference (temperature difference) between the detected drying gas temperature and the gas temperature threshold. Specifically, the fuel flow rate-gas temperature correlation table defines the fuel flow rate to be increased in proportion to the temperature difference when, for example, the drying gas temperature detected by the gas temperature detector 132 is lower than the gas temperature threshold. Also, the fuel flow rate-gas temperature correlation table defines the fuel flow rate to be decreased in proportion to the temperature difference when, for example, the drying gas temperature detected by the gas temperature detector 132 is higher than the gas temperature threshold.

[0100] The calculation unit 180 executes various calculation processes using, for example, programs and data stored in the storage unit 190. The calculation unit 180 includes a VOC concentration determination unit 181 and a temperature determination unit 182.

[0101] The VOC concentration determination unit 181 determines whether the VOC concentration in the exhaust gas is the VOC concentration threshold value, and whether the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value or lower than the VOC concentration threshold value based on the VOC concentration threshold value stored in the threshold memory unit 191 and the detection signal from the VOC concentration detector 143.

[0102] Then, if it is determined that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value or if it is determined that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold value, the VOC concentration determination unit 181 outputs a signal to the output unit 171 for controlling the exhaust fan 142 based on the difference between the VOC concentration in the exhaust gas and the VOC concentration threshold value and the exhaust gas flow rate vs. VOC concentration correlation table stored in the flow rate correlation memory unit 192.

[0103] Furthermore, if it is determined that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value, or if it is determined that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold value, the VOC concentration determination unit 181 outputs a signal to the output unit 171 for controlling the blower 101 based on the exhaust gas flow rate (e.g., the rotation speed of the exhaust fan 142) and the exhaust gas flow rate / air flow rate correlation table.

[0104] The temperature determination unit 182 determines, for example, whether the temperature of the drying gas is equal to the gas temperature threshold value based on the gas temperature threshold value stored in the threshold value storage unit 191 and the detection signal from the gas temperature detector 132. In addition, the temperature determination unit 182 determines, for example, whether the temperature of the drying gas is higher or lower than the gas temperature threshold value.

[0105] Then, for example, when the VOC concentration determination unit 181 determines that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold, and determines that the temperature of the drying gas is higher or lower than the gas temperature threshold, the temperature determination unit 182 controls the dampers 102, 121 and the flow control valve 111 based on the difference between the detected drying gas temperature and the gas temperature threshold, the fuel flow rate vs. gas temperature correlation table and the fuel flow rate vs. air flow rate correlation table stored in the flow rate correlation memory unit 192.

[0106] For example, when it is determined that the temperature of the drying gas is higher than the gas temperature threshold, the temperature determination unit 182 outputs to the output unit 171 a signal for throttling the flow control valve 111 based on the difference between the detected drying gas temperature and the gas temperature threshold and the fuel flow rate vs. gas temperature correlation table, and also outputs to the output unit 171 a signal for throttling the damper 102 based on the fuel flow rate and the fuel flow rate vs. air flow rate correlation table.

[0107] At this time, the temperature determination unit 182 may output a signal for adjusting the opening degree of the damper 121 to the output unit 171.

[0108] In addition, when it is determined that the exhaust gas temperature is lower than the exhaust gas temperature threshold, the temperature determination unit 182 outputs to the output unit 171 a signal for opening the flow control valve 111 based on the difference between the detected drying gas temperature and the gas temperature threshold and the fuel flow rate vs. gas temperature correlation table, and also outputs to the output unit 171 a signal for opening the damper 102 based on the fuel flow rate and the fuel flow rate vs. air flow rate correlation table.

[0109] At this time, the temperature determination unit 182 may output a signal for adjusting the opening degree of the damper 121 to the output unit 171.

[0110] For example, the output unit 171 outputs a control signal from the VOC concentration determination unit 181 to the blower 101 and the exhaust fan 142. In addition, the output unit 171 outputs a control signal from the temperature determination unit 182 to the flow rate adjustment valve 111 and the dampers 102 and 121.

[0111] Here, the processes executed by the control unit 160 described above are realized by, for example, a computer device.

[0112] Here, the operation of the drying equipment 10 will be described.

[0113] First, the operation of the drying furnace 20 will be described.

[0114] 1, dilution air drawn into the dilution air inlet pipe 60 from the atmosphere by a fan 61 is heated as it passes through the condenser 42. The flow rate of the dilution air introduced into the dilution air inlet pipe 60 and the temperature of the dilution air after passing through the condenser 42 are adjusted so that the heating side coefficient of performance (COP) of the heat pump 40 is maximized. After the flow rate and other parameters are adjusted, the flow rate of the dilution air introduced into the dilution air inlet pipe 60 is set to a constant flow rate.

[0115] The heated dilution air is introduced into the combustion device 50. The dilution air is introduced into a gap 53 between a combustion liner 51 and a casing 52, and flows downstream within the gap 53.

[0116] Fuel is introduced into the combustion liner 51 of the combustion device 50 through a fuel introduction pipe 110 and combustion air is introduced through a combustion air introduction pipe 100. The combustion air flowing through the combustion air introduction pipe 100 is heated by exhaust gas flowing through an exhaust pipe 140 via a heat exchanger 141. By introducing the combustion air heated by the exhaust gas into the combustion device 50, the heat quantity of the exhaust gas can be effectively utilized and the fuel flow rate can be reduced.

[0117] Fuel and combustion air are combusted in the combustion liner 51 to generate combustion gas. A mixed gas containing the combustion gas and dilution air is introduced as a drying gas from the combustion device 50 to the drying furnace 20 by the fan 131. This mixed gas also contains the drying gas circulated to the combustion device 50 via the drying gas circulation pipe 150 and the dilution air introduction pipe 60. Here, the temperature of the combustion gas is reduced by mixing the combustion gas with the dilution air. As a result, the temperature of the mixed gas containing the combustion gas and dilution air is adjusted to the temperature required in the drying furnace 20.

[0118] The temperature of the drying gas flowing through the drying gas inlet pipe 130 is detected by a gas temperature detector 132 .

[0119] The drying gas introduced into the drying furnace 20 is sprayed toward the workpiece W moving inside the drying furnace 20. Then, for example, a coating film applied to the workpiece W dries while moving inside the drying furnace 20.

[0120] Here, during steady operation, the damper 121 provided on the branch pipe 120 is in a closed state. That is, during steady operation, air used as combustion air in the combustion device 50 is introduced from the blower 101 to the combustion air introduction pipe 100, and the combustion air does not flow into the dilution air introduction pipe 60 via the branch pipe 120.

[0121] Here, steady operation refers to operation in a state in which the VOC concentration in the exhaust gas is maintained at the VOC concentration threshold value.

[0122] The drying gas used to dry the workpieces W in the drying furnace 20 is exhausted as exhaust gas into the atmosphere via an exhaust pipe 140 by an exhaust fan 142. The VOC concentration contained in the exhaust gas flowing through the exhaust pipe 140 is detected by a VOC concentration detector 143.

[0123] Meanwhile, the drying gas used to dry the workpieces W in the drying furnace 20 is introduced into the dilution air introduction pipe 60 via the drying gas circulation piping 150 by the fan 131. The circulated drying gas is then introduced into the combustion device 50 together with the dilution air flowing through the dilution air introduction pipe 60. That is, the circulated drying gas is introduced into the drying furnace 20 again as drying gas.

[0124] Next, the operation of the cooling furnace 30 will be described.

[0125] Air drawn from the atmosphere into the cooling air introduction pipe 80 by the fan 81 passes through the air-cooling heat exchanger 72 where it is cooled and becomes cooling air.

[0126] The flow rate and temperature of the refrigerant flowing through the refrigerant circulation pipe 71 are adjusted so that the air flowing through the cooling air introduction pipe 80 can be properly cooled while maintaining the cooling side coefficient of performance (COP) of the heat pump 40 at a maximum.

[0127] The cooling air is introduced into the cooling furnace 30 through a cooling air introduction pipe 80. The cooling air introduced into the cooling furnace 30 is sprayed toward the workpieces W moving inside the cooling furnace 30. The workpieces W dried in the drying furnace 20 are guided into the cooling furnace 30 as shown in FIG.

[0128] The cooling air used to cool the workpieces W in the cooling furnace 30 is exhausted into the atmosphere via a cooling air exhaust pipe 90 by an exhaust fan 91.

[0129] Next, the operation of the drying equipment 10 based on the VOC concentration in the exhaust gas flowing through the exhaust pipe 140 will be described.

[0130] Fig. 3 is a flowchart for explaining the action of maintaining the VOC concentration in the exhaust gas at the VOC concentration threshold in the drying equipment 10 of the first embodiment. Fig. 4 is a flowchart for explaining the action of adjusting the temperature of the drying gas among the actions of maintaining the VOC concentration in the exhaust gas at the VOC concentration threshold in the drying equipment 10 of the first embodiment.

[0131] As shown in FIG. 3, the VOC concentration determination unit 181 of the control unit 160 determines whether the VOC concentration in the exhaust gas is equal to the VOC concentration threshold value based on the detection signal from the VOC concentration detector 143 inputted at the input unit 170 and the VOC concentration threshold value stored in the threshold memory unit 191 (step S200).

[0132] During operation of the drying equipment 10, the input unit 170 of the control unit 160 constantly receives the detection signal from the VOC concentration detector 143.

[0133] When it is determined in step S200 that the VOC concentration in the exhaust gas is equal to the VOC concentration threshold value (Yes in step S200), VOC concentration determining unit 181 executes the determination in step S200 again.

[0134] If it is determined in step S200 that the VOC concentration in the exhaust gas is not the VOC concentration threshold (No in step S200), it is determined whether the VOC concentration in the exhaust gas is lower than the VOC concentration threshold based on the detection signal from the VOC concentration detector 143 and the VOC concentration threshold stored in the threshold memory unit 191 (step S201).

[0135] If it is determined in step S201 that the VOC concentration in the exhaust gas is not lower than the VOC concentration threshold, that is, if it is determined that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold (No in step S201), VOC concentration determination unit 181 outputs a signal for controlling exhaust fan 142 to output unit 171 based on the difference (VOC concentration difference) between the VOC concentration in the exhaust gas detected by VOC concentration detector 143 and the VOC concentration threshold and the exhaust gas flow rate vs. VOC concentration correlation table stored in flow rate correlation storage unit 192 (step S202). Then, output unit 171 outputs the signal to exhaust fan 142 (step S202).

[0136] At this time, the VOC concentration determining unit 181 outputs to the output unit 171 a signal for increasing the rotation speed of the exhaust fan 142 based on, for example, the VOC concentration difference and the exhaust gas flow rate vs. VOC concentration correlation table.

[0137] Furthermore, if it is determined in step S201 that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value (No in step S201), VOC concentration determination unit 181 outputs a signal for controlling blower 101 to output unit 171 based on the exhaust gas flow rate (e.g., the rotation speed of exhaust fan 142) and the exhaust gas flow rate / air flow rate correlation table stored in flow rate correlation storage unit 192 (step S203). Then, output unit 171 outputs the signal to blower 101 (step S203).

[0138] At this time, based on the flow rate of the exhaust gas and the exhaust gas flow rate / air flow rate correlation table, the VOC concentration determination unit 181 outputs a signal to the output unit 171 to cause the blower 101 to discharge air at the same flow rate as the flow rate of the exhaust gas. Note that the flow rate here is a volumetric flow rate.

[0139] Next, the temperature determination unit 182 of the control unit 160 adjusts the temperature of the drying gas based on the detection signal from the gas temperature detector 132 and the gas temperature threshold value stored in the threshold value storage unit 191 (step S204).

[0140] Here, the operation of adjusting the temperature of the drying gas in step S204 (steps S204A to S204E) will be described with reference to FIG.

[0141] In step S203, when the flow rate of air discharged from blower 101 is increased, as shown in Fig. 4, temperature determination unit 182 of control unit 160 outputs a signal to output unit 171 to open damper 121 of branch pipe 120 (step S204A). Then, output unit 171 outputs the signal to damper 121 (step S204A).

[0142] Here, the opening degree of the damper 121 is controlled so that excess air relative to the combustion air required for combustion introduced into the combustion liner 51 flows into the dilution air introduction pipe 60 via the branch pipe 120. During steady operation, the damper 121 is closed.

[0143] Next, the temperature determination unit 182 determines whether the temperature of the drying gas is equal to the gas temperature threshold value, based on the detection signal from the gas temperature detector 132 and the gas temperature threshold value stored in the threshold value storage unit 191 (step S204B).

[0144] When it is determined in step S204B that the temperature of the drying gas is equal to the gas temperature threshold value (Yes in step S204B), the temperature determining unit 182 executes the determination in step S204B again.

[0145] If it is determined in step S204B that the temperature of the drying gas is not the gas temperature threshold (No in step S204B), the temperature determination unit 182 determines whether the temperature of the drying gas is lower than the gas temperature threshold based on the detection signal from the gas temperature detector 132 and the gas temperature threshold stored in the threshold memory unit 191 (step S204C).

[0146] When it is determined in step S204C that the temperature of the drying gas is lower than the gas temperature threshold (Yes in step S204C), the temperature determination unit 182 calculates the temperature difference between the temperature of the drying gas and the gas temperature threshold (step S204D). Then, based on the calculated temperature difference and the fuel flow rate-gas temperature correlation table stored in the flow rate correlation storage unit 192, the temperature determination unit 182 outputs a signal to the output unit 171 to control the flow rate adjustment valve 111 to increase the fuel flow rate (step S204D). The output unit 171 outputs the signal to the flow rate adjustment valve 111 (step S204D).

[0147] Here, the temperature determination unit 182 obtains information relating to the fuel flow rate based on the output signal from the fuel flow meter 112 inputted by the input unit 170 .

[0148] Furthermore, the temperature determination unit 182 outputs a signal to the output unit 171 to increase the opening of the damper 102 and increase the flow rate of the combustion air introduced into the combustion liner 51 based on the fuel flow rate-air flow rate correlation table stored in the fuel flow rate and flow rate correlation storage unit 192 (step S204D). Then, the output unit 171 outputs the signal to the damper 102 (step S204D).

[0149] At this time, the temperature determination unit 182 adjusts the opening of the damper 121 so that the combustion air required for combustion is introduced into the combustion liner 51.

[0150] Then, after executing step S204D, temperature determining unit 182 executes the determination of step S204B again.

[0151] If it is determined in step S204C that the temperature of the drying gas is not lower than the gas temperature threshold, that is, if it is determined that the temperature of the drying gas is higher than the gas temperature threshold (No in step S204C), the temperature determination unit 182 calculates the temperature difference between the temperature of the drying gas and the gas temperature threshold (step S204E). Then, based on the calculated temperature difference and the fuel flow rate-gas temperature correlation table stored in the flow rate correlation storage unit 192, the temperature determination unit 182 outputs a signal to the output unit 171 to control the flow rate adjustment valve 111 to reduce the fuel flow rate (step S204E). The output unit 171 outputs the signal to the flow rate adjustment valve 111 (step S204E).

[0152] Here, the temperature determination unit 182 obtains information relating to the fuel flow rate based on the output signal from the fuel flow meter 112 inputted by the input unit 170 .

[0153] Furthermore, the temperature determination unit 182 outputs a signal to the output unit 171 to reduce the opening of the damper 102 and decrease the flow rate of the combustion air introduced into the combustion liner 51 based on the fuel flow rate / air flow rate correlation table stored in the fuel flow rate and flow rate correlation storage unit 192 (step S204E). Then, the output unit 171 outputs the signal to the damper 102 (step S204E).

[0154] At this time, the temperature determination unit 182 adjusts the opening of the damper 121 so that the combustion air required for combustion is introduced into the combustion liner 51.

[0155] After executing step S204E, temperature determining unit 182 performs the determination of step S204B again.

[0156] After performing the temperature adjustment of the drying gas in step S204 (steps S204A to S204E) described above, as shown in FIG. 3, the VOC concentration determination unit 181 determines whether or not there is a signal related to the end of operation of the drying equipment 10, based on the input signal from the input unit 170 (step S205).

[0157] When it is determined in step S205 that there is a signal related to the end of the operation of the drying equipment 10 (Yes in step S205), the VOC concentration determining unit 181 executes a process for ending the operation of the drying equipment 10.

[0158] The process for terminating the operation of the drying equipment 10 may be executed by a determination unit other than the VOC concentration determination unit 181.

[0159] When it is determined in step S205 that there is no signal related to the end of operation of the drying equipment 10 (No in step S205), the VOC concentration determining unit 181 executes the process from step S200 again.

[0160] If it is determined in step S201 that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold (Yes in step S201), VOC concentration determination unit 181 outputs a signal for controlling exhaust fan 142 to output unit 171 based on the difference (VOC concentration difference) between the VOC concentration in the exhaust gas detected by VOC concentration detector 143 and the VOC concentration threshold and the exhaust gas flow rate vs. VOC concentration correlation table stored in flow rate correlation storage unit 192 (step S206). Then, output unit 171 outputs the signal to exhaust fan 142 (step S206).

[0161] At this time, the VOC concentration determining unit 181 outputs to the output unit 171 a signal for decreasing the rotation speed of the exhaust fan 142 based on, for example, the VOC concentration difference and the exhaust gas flow rate vs. VOC concentration correlation table.

[0162] Furthermore, if it is determined in step S201 that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold value (Yes in step S201), VOC concentration determination unit 181 outputs a signal for controlling blower 101 to output unit 171 based on the exhaust gas flow rate (e.g., the rotation speed of exhaust fan 142) and the exhaust gas flow rate / air flow rate correlation table stored in flow rate correlation storage unit 192 (step S207). Then, output unit 171 outputs the signal to blower 101 (step S207).

[0163] At this time, the VOC concentration determining unit 181 outputs a signal to the output unit 171 to cause the blower 101 to discharge air at the same flow rate as the exhaust gas flow rate, based on the exhaust gas flow rate and the exhaust gas flow rate / air flow rate correlation table.

[0164] Next, the temperature determination unit 182 of the control unit 160 adjusts the temperature of the drying gas based on the detection signal from the gas temperature detector 132 and the gas temperature threshold value stored in the threshold value storage unit 191 (step S208).

[0165] In step S208, the same process as that in step S204 described above is executed. That is, in step S208, the processes in steps S204A to S204E shown in FIG.

[0166] At this time, if air exceeding the air flow rate required for combustion air is being introduced from the blower 101 into the combustion air introduction pipe 100, the temperature determination unit 182 outputs a signal to the output unit 171 to appropriately adjust the opening of the damper 121 of the branch pipe 120 (step S204A). On the other hand, if only air with the air flow rate required for combustion air is being introduced from the blower 101 into the combustion air introduction pipe 100, the temperature determination unit 182 outputs a signal to the output unit 171 to close the damper 121 of the branch pipe 120 (step S204A).

[0167] After the temperature adjustment of the drying gas is performed in step S208, as shown in FIG. 3, the VOC concentration determination unit 181 determines whether or not there is a signal related to the end of operation of the drying equipment 10, based on the input signal from the input unit 170 (step S209).

[0168] When it is determined in step S209 that there is a signal related to the end of the operation of the drying equipment 10 (Yes in step S209), a process for ending the operation of the drying equipment 10 is executed.

[0169] When it is determined in step S209 that there is no signal related to the end of operation of the drying equipment 10 (No in step S209), the VOC concentration determining unit 181 executes the process from step S200 again.

[0170] As described above, in the drying equipment 10 of the first embodiment, the VOC concentration in the exhaust gas can be maintained at the VOC concentration threshold value.

[0171] In the drying equipment 10, for example, when the VOC concentration in the exhaust gas is higher than the VOC concentration threshold, the flow rate of the exhaust gas discharged from the drying furnace 20 can be increased, and the flow rate of the drying gas introduced into the drying furnace 20 can be increased.

[0172] On the other hand, when the VOC concentration in the exhaust gas is lower than the VOC concentration threshold, the flow rate of the exhaust gas discharged from the drying furnace 20 can be reduced, and the flow rate of the drying gas introduced into the drying furnace 20 can be reduced.

[0173] In addition, in the drying equipment 10, the flow rate of the exhaust gas discharged from the drying furnace 20 and the flow rate of the drying gas introduced into the drying furnace 20 can be appropriately adjusted based on the difference between the VOC concentration in the exhaust gas and the VOC concentration threshold value.

[0174] Here, examples of cases in which the VOC concentration becomes higher than the VOC concentration threshold include when many workpieces W are dried at once in the drying furnace 20, or when the size of the workpieces W to be dried is large. In these cases, a large amount of VOC contained in the coating evaporates in the drying furnace 20, and the VOC concentration becomes higher than the VOC concentration threshold.

[0175] On the other hand, cases in which the VOC concentration becomes lower than the VOC concentration threshold include when the number of workpieces W to be dried at one time in the drying furnace 20 is small, or when the size of the workpieces W to be dried is small. In these cases, the amount of VOC generated in the drying furnace 20 is small, and the VOC concentration becomes lower than the VOC concentration threshold.

[0176] In either case, the VOC concentration in the exhaust gas, i.e., the VOC concentration in the drying furnace 20, can be maintained at the VOC concentration threshold by adjusting the flow rate of the exhaust gas discharged from the drying furnace 20 and the flow rate of the drying gas introduced into the drying furnace 20 according to the VOC concentration in the exhaust gas.

[0177] In the drying equipment 10, the VOC concentration in the exhaust gas can be maintained at the VOC concentration threshold by adjusting the flow rate of the exhaust gas discharged from the drying furnace 20 and the flow rate of the drying gas introduced into the drying furnace 20, without the need for a device to recover and remove the VOCs contained in the exhaust gas.

[0178] In addition, in the drying equipment 10, by discharging air from the blower 101 at the same flow rate as the exhaust gas, it is possible to introduce drying gas into the drying oven 20 at the same flow rate as the exhaust gas discharged from the drying oven 20. This makes it possible to maintain the pressure inside the drying oven 20 constant.

[0179] Furthermore, the drying equipment 10 is provided with a branch pipe 120, and by adjusting the opening of the damper 121, it is possible to introduce the air required for combustion into the combustion liner 51 while introducing surplus air into the dilution air introduction pipe 60. In other words, it is possible to introduce an appropriate flow rate of air into the combustion liner 51 while increasing the flow rate of the drying gas.

[0180] The drying equipment 10 includes a temperature determination unit 182 and adjusts the fuel flow rate and the combustion air flow rate in steps S204 (steps S204A to S204E) and S208, so that drying gas at the gas temperature threshold value can be introduced into the drying oven 20 even when the flow rate of the drying gas is increased or decreased to maintain the VOC concentration in the drying oven 20 at the VOC concentration threshold value. Furthermore, the drying equipment 10 can appropriately set the flow rate of fuel introduced into the combustion device 50 based on, for example, the difference between the temperature of the drying gas introduced into the drying oven 20 and the gas temperature threshold value.

[0181] As a result, the workpieces W can be properly dried even when a process for maintaining the VOC concentration in the drying furnace 20 at the VOC concentration threshold value is being performed.

[0182] In the drying equipment 10, the air flowing through the combustion air introduction pipe 100 is heated by the exhaust gas flowing through the exhaust pipe 140 via the heat exchanger 141. This makes it possible to effectively utilize the heat contained in the exhaust gas. Furthermore, by introducing this heated air into the combustion device 50, the flow rate of fuel introduced into the combustion device 50 can be reduced.

[0183] Furthermore, the drying equipment 10 can perform processing to maintain the VOC concentration at the VOC concentration threshold value by having a simple configuration while maintaining the condition that maximizes the coefficient of performance (COP) of the heat pump 40.

[0184] Furthermore, even in existing drying equipment that does not have the function of removing VOCs, the configuration shown in the first embodiment for maintaining the VOC concentration at the VOC concentration threshold value can be provided without the need for large-scale expansion work.

[0185] In other words, by equipping an existing drying equipment with, for example, a branch pipe 120 having a damper 121 and a control unit 160, the existing drying equipment can be provided with a configuration for maintaining the VOC concentration shown in the first embodiment at the VOC concentration threshold value without increasing the size or complexity of the equipment.

[0186] (Second embodiment) 5 is a diagram showing a schematic overview of the drying equipment 11 according to the second embodiment. In the second embodiment, the same components as those in the drying equipment 10 according to the first embodiment are denoted by the same reference numerals, and duplicated descriptions are omitted or simplified.

[0187] In the drying equipment 11 of the second embodiment, the configurations of the introduction system for combustion air and the introduction system for introducing the increased air (dilution air) when the VOC concentration in the exhaust gas exceeds the VOC concentration threshold into the first dilution air introduction pipe 60A are different from those of the drying equipment 10 of the first embodiment. Here, the different configurations will be mainly described.

[0188] 5, the drying equipment 10 includes a drying furnace 20 and a cooling furnace 30. The drying equipment 10 also includes a combustion device 50, a combustion air introduction pipe 300, a fuel introduction pipe 110, a first dilution air introduction pipe 60A, a second dilution air introduction pipe 310, a drying gas introduction pipe 130, an exhaust pipe 140, and a drying gas circulation pipe 150. The drying equipment 10 also includes a control unit 160 that controls the drying equipment 10.

[0189] The first dilution air introduction pipe 60A has the same configuration as the dilution air introduction pipe 60 in the drying equipment 10 of the first embodiment. The action of the first dilution air introduction pipe 60A is also the same as the action of the dilution air introduction pipe 60 in the drying equipment 10 of the first embodiment.

[0190] Here, the combustion air introduction pipe 300 and the second dilution air introduction pipe 310 will be mainly described.

[0191] The combustion air introduction pipe 300 introduces combustion air to the combustion device 50. Specifically, the combustion air introduction pipe 300 is connected to the combustion liner 51 and introduces air into the combustion liner 51. The combustion air introduction pipe 300 is provided with a blower 301 that introduces outside air into the combustion air introduction pipe 300 and leads it to the combustion device 50. The blower 301 functions as a first air supplier. For example, a fan may be used as the first air supplier.

[0192] The second dilution air introduction pipe 310 is provided so as to be able to introduce air (dilution air) into the first dilution air introduction pipe 60A. Specifically, the second dilution air introduction pipe 310 is connected to the first dilution air introduction pipe 60A between the heat pump 40 and the combustion device 50.

[0193] The second dilution air introduction pipe 310 is provided with a blower 311 that introduces outside air into the second dilution air introduction pipe 310 and guides it to the first dilution air introduction pipe 60A. The blower 311 functions as a second air supplier. For example, a fan may be used as the second air supplier.

[0194] 5, a portion of the second dilution air introduction pipe 310 is configured to be able to exchange heat with the drying gas flowing through the exhaust pipe 140. The second dilution air introduction pipe 310 is, for example, piped so as to pass through a heat exchanger 141 provided in the exhaust pipe 140. The air flowing through the second dilution air introduction pipe 310 is heated by the exhaust gas via the heat exchanger 141.

[0195] The air flowing through the second dilution air introduction pipe 310 is introduced into the combustion device 50 as dilution air together with the air flowing through the first dilution air introduction pipe 60A.

[0196] Here, the blower 311 provided in the second dilution air introduction pipe 310 is operated so as to introduce air into the second dilution air introduction pipe 310 at a flow rate equal to the flow rate of the exhaust gas exhausted by the exhaust fan 142. That is, under operating conditions in which the exhaust gas is exhausted from the drying furnace 20, the blower 311 is constantly operating.

[0197] Here, the drying gas circulation pipe 150 is connected to the first dilution air introduction pipe 60A, for example, on the heat pump 40 side of the position where the second dilution air introduction pipe 310 is connected to the first dilution air introduction pipe 60A. Note that the connection portion of the drying gas circulation pipe 150 to the first dilution air introduction pipe 60A may be on the combustion device 50 side of the connection portion of the second dilution air introduction pipe 310 to the first dilution air introduction pipe 60A.

[0198] The control unit 160 controls, for example, the exhaust fan 142 and the blower 311 based on a signal detected by the VOC concentration detector 143. The control unit 160 also controls, for example, the blower 301 and the flow rate adjustment valve 111 based on a signal detected by the gas temperature detector 132.

[0199] Here, in the drying equipment 11 of the second embodiment, the control unit 160 includes an input unit 170, a calculation unit 180, a storage unit 190, and an output unit 171, similar to the configuration shown in FIG.

[0200] Here, differences between the functions of each component of the control unit 160 of the drying equipment 11 of the second embodiment and the functions of each component of the control unit 160 of the drying equipment 10 of the first embodiment will be mainly described.

[0201] As described above, the storage unit 190 includes the threshold storage unit 191 and the flow rate correlation storage unit 192 (see FIG. 2).

[0202] The flow rate correlation memory unit 192 stores an exhaust gas flow rate / air flow rate correlation table for introducing air at the same flow rate as the flow rate of the exhaust gas exhausted by the exhaust fan 142 from the blower 311 into the second dilution air introduction pipe 310.

[0203] Specifically, the exhaust gas flow rate / air flow rate correlation table is made up of correlation data that defines the rotation speed of blower 311 for discharging air at the same flow rate as the exhausted exhaust gas flow rate. For example, the exhaust gas flow rate / air flow rate correlation table is made up of correlation data that defines the correspondence between the rotation speed of exhaust fan 142 and the rotation speed of blower 311.

[0204] Furthermore, the flow rate correlation storage unit 192 stores, for example, a fuel flow rate-air flow rate correlation table for setting the flow rate of combustion air based on the fuel flow rate. The fuel flow rate-air flow rate correlation table is composed of, for example, correlation data that defines the air flow rate corresponding to the fuel flow rate. Specifically, the fuel flow rate-air flow rate correlation table is composed of correlation data that defines the rotation speed of the blower 301 based on the fuel flow rate.

[0205] As described above, the calculation unit 180 includes the VOC concentration determination unit 181 and the temperature determination unit 182 (see FIG. 2).

[0206] The VOC concentration determination unit 181 determines whether the VOC concentration in the exhaust gas is the VOC concentration threshold value, and whether the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value or lower than the VOC concentration threshold value based on the VOC concentration threshold value stored in the threshold memory unit 191 and the detection signal from the VOC concentration detector 143.

[0207] Then, if it is determined that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value or if it is determined that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold value, the VOC concentration determination unit 181 outputs a signal to the output unit 171 for controlling the exhaust fan 142 based on the difference between the VOC concentration in the exhaust gas and the VOC concentration threshold value and the exhaust gas flow rate vs. VOC concentration correlation table stored in the flow rate correlation memory unit 192.

[0208] Furthermore, if it is determined that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value, or if it is determined that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold value, the VOC concentration determination unit 181 outputs a signal to the output unit 171 for controlling the blower 311 based on the exhaust gas flow rate (e.g., the rotation speed of the exhaust fan 142) and the exhaust gas flow rate / air flow rate correlation table.

[0209] The temperature determination unit 182 determines, for example, whether the temperature of the drying gas is equal to the gas temperature threshold value based on the gas temperature threshold value stored in the threshold value storage unit 191 and the detection signal from the gas temperature detector 132. In addition, the temperature determination unit 182 determines, for example, whether the temperature of the drying gas is higher or lower than the gas temperature threshold value.

[0210] Then, for example, when the VOC concentration determination unit 181 determines that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold, if it determines that the temperature of the drying gas is higher or lower than the gas temperature threshold, the temperature determination unit 182 controls the blower 301 and the flow rate control valve 111 based on the difference between the detected drying gas temperature and the gas temperature threshold, and the fuel flow rate vs. gas temperature correlation table and the fuel flow rate vs. air flow rate correlation table stored in the flow rate correlation memory unit 192.

[0211] For example, when it is determined that the temperature of the drying gas is higher than the gas temperature threshold value, the temperature determination unit 182 outputs to the output unit 171 a signal for throttling the flow control valve 111 based on the fuel flow rate vs. gas temperature correlation table, and also outputs to the output unit 171 a signal for reducing the rotation speed of the blower 301 based on the fuel flow rate vs. air flow rate correlation table.

[0212] In addition, if it is determined that the temperature of the exhaust gas is lower than the exhaust gas temperature threshold value, the temperature determination unit 182 outputs to the output unit 171 a signal to open the flow control valve 111 based on the fuel flow rate vs. gas temperature correlation table, and also outputs to the output unit 171 a signal to increase the rotation speed of the blower 301 based on the fuel flow rate vs. air flow rate correlation table.

[0213] For example, the output unit 171 outputs a control signal from the VOC concentration determination unit 181 to the exhaust fan 142 and the blower 311. In addition, the output unit 171 outputs a control signal from the temperature determination unit 182 to the flow rate adjustment valve 111 and the blower 301.

[0214] Next, the operation of the drying equipment 11 based on the VOC concentration in the exhaust gas flowing through the exhaust pipe 140 will be described.

[0215] Here, the operation of the drying equipment 11 of the second embodiment will be described with reference to Figs. 3 and 4 shown in the explanation of the operation of the drying equipment 10 of the first embodiment.

[0216] As shown in FIG. 3, the VOC concentration determination unit 181 of the control unit 160 determines whether the VOC concentration in the exhaust gas is equal to the VOC concentration threshold value based on the detection signal from the VOC concentration detector 143 inputted at the input unit 170 and the VOC concentration threshold value stored in the threshold memory unit 191 (step S200).

[0217] During operation of the drying equipment 10, the input unit 170 of the control unit 160 constantly receives the detection signal from the VOC concentration detector 143.

[0218] When it is determined in step S200 that the VOC concentration in the exhaust gas is equal to the VOC concentration threshold value (Yes in step S200), VOC concentration determining unit 181 executes the determination in step S200 again.

[0219] If it is determined in step S200 that the VOC concentration in the exhaust gas is not the VOC concentration threshold (No in step S200), it is determined whether the VOC concentration in the exhaust gas is lower than the VOC concentration threshold based on the detection signal from the VOC concentration detector 143 and the VOC concentration threshold stored in the threshold memory unit 191 (step S201).

[0220] If it is determined in step S201 that the VOC concentration in the exhaust gas is not lower than the VOC concentration threshold, that is, if it is determined that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold (No in step S201), VOC concentration determination unit 181 outputs a signal for controlling exhaust fan 142 to output unit 171 based on the difference (VOC concentration difference) between the VOC concentration in the exhaust gas detected by VOC concentration detector 143 and the VOC concentration threshold and the exhaust gas flow rate vs. VOC concentration correlation table stored in flow rate correlation storage unit 192 (step S202). Then, output unit 171 outputs the signal to exhaust fan 142 (step S202).

[0221] At this time, the VOC concentration determining unit 181 outputs to the output unit 171 a signal for increasing the rotation speed of the exhaust fan 142 based on, for example, the VOC concentration difference and the exhaust gas flow rate vs. VOC concentration correlation table.

[0222] Furthermore, if it is determined in step S201 that the VOC concentration in the exhaust gas is higher than the VOC concentration threshold value (No in step S201), VOC concentration determination unit 181 outputs a signal for controlling blower 311 to output unit 171 based on the exhaust gas flow rate (e.g., the rotation speed of exhaust fan 142) and the exhaust gas flow rate / air flow rate correlation table stored in flow rate correlation storage unit 192 (step S203). Then, output unit 171 outputs the signal to blower 311 (step S203).

[0223] At this time, VOC concentration determining unit 181 outputs a signal to output unit 171 to cause blower 311 to discharge air at the same flow rate as the exhaust gas flow rate, based on the exhaust gas flow rate and the exhaust gas flow rate / air flow rate correlation table.

[0224] Next, the temperature determination unit 182 of the control unit 160 adjusts the temperature of the drying gas based on the detection signal from the gas temperature detector 132 and the gas temperature threshold value stored in the threshold value storage unit 191 (step S204).

[0225] Here, the operation of adjusting the temperature of the drying gas in step S204 will be described with reference to FIG.

[0226] In the drying equipment 11, the process in step S204A in Fig. 4 is not executed. Therefore, in the drying equipment 11, the process from step S204B in Fig. 4 is executed.

[0227] The temperature determination unit 182 determines whether the temperature of the drying gas is equal to the gas temperature threshold value, based on the detection signal from the gas temperature detector 132 and the gas temperature threshold value stored in the threshold value storage unit 191 (step S204B).

[0228] When it is determined in step S204B that the temperature of the drying gas is equal to the gas temperature threshold value (Yes in step S204B), the temperature determining unit 182 executes the determination in step S204B again.

[0229] If it is determined in step S204B that the temperature of the drying gas is not the gas temperature threshold (No in step S204B), the temperature determination unit 182 determines whether the temperature of the drying gas is lower than the gas temperature threshold based on the detection signal from the gas temperature detector 132 and the gas temperature threshold stored in the threshold memory unit 191 (step S204C).

[0230] When it is determined in step S204C that the temperature of the drying gas is lower than the gas temperature threshold (Yes in step S204C), the temperature determination unit 182 calculates the temperature difference between the temperature of the drying gas and the gas temperature threshold (step S204D). Then, based on the calculated temperature difference and the fuel flow rate-gas temperature correlation table stored in the flow rate correlation storage unit 192, the temperature determination unit 182 outputs a signal to the output unit 171 to control the flow rate adjustment valve 111 to increase the fuel flow rate (step S204D). The output unit 171 outputs the signal to the flow rate adjustment valve 111 (step S204D).

[0231] Furthermore, the temperature determination unit 182 outputs a signal to the output unit 171 to increase the rotation speed of the blower 301 and increase the flow rate of the combustion air introduced into the combustion liner 51 based on the fuel flow rate-air flow rate correlation table stored in the fuel flow rate and flow rate correlation storage unit 192 (step S204D). Then, the output unit 171 outputs the signal to the blower 301 (step S204D).

[0232] Then, after executing step S204D, temperature determining unit 182 executes the determination of step S204B again.

[0233] If it is determined in step S204C that the temperature of the drying gas is not lower than the gas temperature threshold, that is, if it is determined that the temperature of the drying gas is higher than the gas temperature threshold (No in step S204C), the temperature determination unit 182 calculates the temperature difference between the temperature of the drying gas and the gas temperature threshold (step S204E). Then, based on the calculated temperature difference and the fuel flow rate-gas temperature correlation table stored in the flow rate correlation storage unit 192, the temperature determination unit 182 outputs a signal to the output unit 171 to control the flow rate adjustment valve 111 to reduce the fuel flow rate (step S204E). The output unit 171 outputs the signal to the flow rate adjustment valve 111 (step S204E).

[0234] Furthermore, the temperature determination unit 182 outputs a signal to the output unit 171 to reduce the rotation speed of the blower 301 and reduce the flow rate of the combustion air introduced into the combustion liner 51 based on the fuel flow rate / air flow rate correlation table stored in the fuel flow rate and flow rate correlation storage unit 192 (step S204E). Then, the output unit 171 outputs the signal to the blower 301 (step S204E).

[0235] After executing step S204E, temperature determining unit 182 performs the determination of step S204B again.

[0236] After performing the temperature adjustment of the drying gas in step S204 (steps S204B to S204E) described above, as shown in FIG. 3, the VOC concentration determination unit 181 determines whether or not there is a signal related to the end of operation of the drying equipment 10, based on the input signal from the input unit 170 (step S205).

[0237] When it is determined in step S205 that there is a signal related to the end of the operation of the drying equipment 10 (Yes in step S205), the VOC concentration determining unit 181 executes a process for ending the operation of the drying equipment 10.

[0238] The process for terminating the operation of the drying equipment 10 may be executed by a determination unit other than the VOC concentration determination unit 181.

[0239] When it is determined in step S205 that there is no signal related to the end of operation of the drying equipment 10 (No in step S205), the VOC concentration determining unit 181 executes the process from step S200 again.

[0240] If it is determined in step S201 that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold (Yes in step S201), VOC concentration determination unit 181 outputs a signal for controlling exhaust fan 142 to output unit 171 based on the difference (VOC concentration difference) between the VOC concentration in the exhaust gas detected by VOC concentration detector 143 and the VOC concentration threshold and the exhaust gas flow rate vs. VOC concentration correlation table stored in flow rate correlation storage unit 192 (step S206). Then, output unit 171 outputs the signal to exhaust fan 142 (step S206).

[0241] At this time, the VOC concentration determining unit 181 outputs to the output unit 171 a signal for decreasing the rotation speed of the exhaust fan 142 based on, for example, the VOC concentration difference and the exhaust gas flow rate vs. VOC concentration correlation table.

[0242] Furthermore, if it is determined in step S201 that the VOC concentration in the exhaust gas is lower than the VOC concentration threshold value (Yes in step S201), VOC concentration determination unit 181 outputs a signal for controlling blower 311 to output unit 171 based on the exhaust gas flow rate (e.g., the rotation speed of exhaust fan 142) and the exhaust gas flow rate / air flow rate correlation table stored in flow rate correlation storage unit 192 (step S207). Then, output unit 171 outputs the signal to blower 311 (step S207).

[0243] At this time, VOC concentration determining unit 181 outputs a signal to output unit 171 to cause blower 311 to discharge air at the same flow rate as the exhaust gas flow rate, based on the exhaust gas flow rate and the exhaust gas flow rate / air flow rate correlation table.

[0244] Next, the temperature determination unit 182 of the control unit 160 adjusts the temperature of the drying gas based on the detection signal from the gas temperature detector 132 and the gas temperature threshold value stored in the threshold value storage unit 191 (step S208).

[0245] In step S208, the same process as that in step S204 described above is executed. That is, in step S208, the processes in steps S204B to S204E shown in FIG.

[0246] After the temperature adjustment of the drying gas is performed in step S208, as shown in FIG. 3, the VOC concentration determination unit 181 determines whether or not there is a signal related to the end of operation of the drying equipment 10, based on the input signal from the input unit 170 (step S209).

[0247] When it is determined in step S209 that there is a signal related to the end of the operation of the drying equipment 10 (Yes in step S209), a process for ending the operation of the drying equipment 10 is executed.

[0248] When it is determined in step S209 that there is no signal related to the end of operation of the drying equipment 10 (No in step S209), the VOC concentration determining unit 181 executes the process from step S200 again.

[0249] During VOC concentration adjustment operation in the drying equipment 11 of the second embodiment, depending on the operating conditions, the flow rate of the drying gas introduced into the drying furnace 20 may be greater than the flow rate of the exhaust gas discharged by the exhaust fan 142.

[0250] In such a case, the excess drying gas may be introduced, for example, into a setting zone provided upstream of the drying furnace 20 (upstream in the conveying direction of the workpieces W). This makes it possible to maintain the pressure inside the drying furnace 20 constant.

[0251] In the drying equipment 11 of the second embodiment, it is possible to obtain the same effects as those of the drying equipment 10 of the first embodiment.

[0252] In addition, in the drying equipment 11, the second dilution air introduction pipe 310 through which air introduced from the outside by the blower 311 flows, and the combustion air introduction pipe 300 through which combustion air is introduced into the combustion device 50 are configured as independent and separate systems.

[0253] This makes it possible to independently control the flow rate of air introduced into the first dilution air introduction pipe 60A via the second dilution air introduction pipe 310 and the flow rate of combustion air introduced into the combustion device 50 via the combustion air introduction pipe 300.

[0254] In the drying equipment 11, the air flowing through the second dilution air introduction pipe 310 is heated by the exhaust gas flowing through the exhaust pipe 140 via the heat exchanger 141. This makes it possible to effectively utilize the heat contained in the exhaust gas. Furthermore, by introducing this heated air into the combustion device 50, the flow rate of fuel introduced into the combustion device 50 can be reduced.

[0255] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0256] 10, 11... drying equipment, 20... drying furnace, 30... cooling furnace, 40... heat pump, 41... refrigerant flow path, 42... condenser, 43... evaporator, 44... compressor, 45... expansion valve, 50... combustion device, 51... combustion liner, 52... casing, 53... gap, 60... dilution air inlet pipe, 60A... first dilution air inlet pipe, 61, 81, 131... fan, 70... air cooling mechanism, 71... refrigerant circulation piping, 72... air cooling heat exchanger, 73... circulation pump, 74... refrigerant heating heat exchanger, 80... cooling air inlet pipe, 90... cooling air exhaust pipe, 91, 142... exhaust fan, 100, 300... combustion air inlet pipe, 101, 301, 311...blower, 102, 121...damper, 110...fuel inlet pipe, 111...flow control valve, 112...fuel flow meter, 120...branch pipe, 130...drying gas inlet pipe, 132...gas temperature detector, 140...exhaust pipe, 141...heat exchanger, 143...VOC concentration detector, 145...branch exhaust pipe, 146...flow control valve, 150...drying gas circulation piping, 160...control unit, 170...input unit, 171...output unit, 180...calculation unit, 181...VOC concentration determination unit, 182...temperature determination unit, 190...memory unit, 191...threshold memory unit, 192...flow rate correlation memory unit, 310...second dilution air inlet pipe, W...work.

Claims

1. A combustion device; A combustion air introduction pipe that is equipped with an air supplier and an air flow rate adjustment unit and introduces combustion air into the combustion device; a fuel introduction pipe including a fuel flow rate control valve and configured to introduce fuel into the combustion device; A dilution air introduction pipe for introducing dilution air into the combustion device; a heat pump including a heating heat exchanger for heating the dilution air flowing through the dilution air inlet pipe; A branch pipe that branches off from the combustion air introduction pipe between the air supplier and the air flow rate regulator and is connected to the dilution air introduction pipe; A drying device for drying the object to be dried; a drying gas introduction pipe for introducing a mixed gas containing the combustion gas generated in the combustion device and dilution air as a drying gas into the drying device; an exhaust pipe including an exhaust fan and configured to exhaust the drying gas from the drying device; a drying gas circulation pipe that introduces the drying gas from the drying device to the dilution air introduction pipe and circulates it to the combustion device; a VOC concentration detector for detecting a concentration of volatile organic compounds contained in the drying gas in the drying device; a gas temperature detector for detecting a temperature of the drying gas in the drying device; a control unit that controls the exhaust blower and the air supply unit based on a detection signal from the VOC concentration detector, and controls the air flow rate adjustment unit and the fuel flow rate adjustment valve based on a detection signal from the gas temperature detector; A drying facility comprising:

2. A combustion device; a combustion air introduction pipe including a first air supplier and introducing combustion air into the combustion device; a fuel introduction pipe including a fuel flow rate control valve and configured to introduce fuel into the combustion device; a first dilution air introduction pipe for introducing dilution air into the combustion device; a heat pump including a heating heat exchanger for heating the dilution air flowing through the first dilution air introduction pipe; a second dilution air introduction pipe including a second air supplier and connected to the first dilution air introduction pipe; A drying device for drying the object to be dried; a drying gas introduction pipe for introducing a mixed gas containing the combustion gas generated in the combustion device and dilution air as a drying gas into the drying device; an exhaust pipe including an exhaust fan and configured to exhaust the drying gas from the drying device; a drying gas circulation pipe that introduces the drying gas from the drying device to the first dilution air introduction pipe and circulates it to the combustion device; a VOC concentration detector for detecting a concentration of volatile organic compounds contained in the drying gas in the drying device; a gas temperature detector for detecting a temperature of the drying gas in the drying device; a control unit that controls the exhaust blower and the second air supplier based on a detection signal from the VOC concentration detector, and controls the first air supplier and the fuel flow rate control valve based on a detection signal from the gas temperature detector; A drying facility comprising:

3. 3. The drying equipment according to claim 1, wherein the VOC concentration detector detects the concentration of volatile organic compounds contained in the drying gas at at least one location in the exhaust pipe, the drying gas circulation pipe, and the drying device.

4. 4. The drying facility according to claim 1, wherein the gas temperature detector detects the temperature of the drying gas at least at one location in the drying gas inlet pipe, the drying device, and the drying gas circulation pipe.

5. The drying equipment comprises: A cooling device for cooling the material to be dried; a cooling air introduction pipe for introducing cooling air into the cooling device; an air cooling mechanism that cools the cooling air flowing through the cooling air introduction pipe; Equipped with The air cooling mechanism includes: A refrigerant circulation pipe for circulating the refrigerant; a refrigerant cooling heat exchanger provided in the heat pump and configured to cool the refrigerant flowing through the refrigerant circulation pipe; an air cooling heat exchanger that cools the cooling air flowing through the cooling air introduction pipe by the refrigerant flowing through the refrigerant circulation pipe; 5. The drying facility according to claim 1, further comprising:

6. A combustion device; A combustion air introduction pipe having an air supplier and introducing combustion air into the combustion device; A fuel introduction pipe for introducing fuel into the combustion device; A dilution air introduction pipe for introducing dilution air heated by a heat pump into the combustion device; A branch pipe branched from the combustion air introduction pipe and connected to the dilution air introduction pipe; A drying device for drying the object to be dried; a drying gas introduction pipe for introducing a mixed gas containing the combustion gas generated in the combustion device and dilution air as a drying gas into the drying device; an exhaust pipe including an exhaust fan and configured to exhaust the drying gas from the drying device; a drying gas circulation pipe that introduces the drying gas from the drying device to the dilution air introduction pipe and circulates it to the combustion device; a VOC concentration detector for detecting a concentration of volatile organic compounds contained in the drying gas in the drying device; a gas temperature detector for detecting a temperature of the drying gas in the drying device; A method for controlling a VOC concentration in a drying facility comprising: a VOC concentration determination unit controls the exhaust blower to adjust a flow rate of the drying gas exhausted from the drying device based on the concentration of the volatile organic compounds detected by the VOC concentration detector so that the concentration of the volatile organic compounds is maintained at a predetermined concentration, and controls the air supply unit to introduce air at a flow rate equal to the flow rate of the drying gas exhausted from the drying device into the combustion air introduction pipe; a temperature determination unit that adjusts the flow rate of fuel introduced from the fuel inlet pipe to the combustion device based on the temperature of the drying gas detected by the gas temperature detector so that the temperature of the drying gas is maintained at a predetermined temperature, and that adjusts the flow rate of combustion air flowing into the combustion air inlet pipe and the flow rate of air flowing into the branch pipe based on the fuel flow rate.

7. A combustion device; a combustion air introduction pipe including a first air supplier and introducing combustion air into the combustion device; A fuel introduction pipe for introducing fuel into the combustion device; a first dilution air introduction pipe for introducing dilution air heated by a heat pump into the combustion device; a second dilution air introduction pipe including a second air supplier and connected to the first dilution air introduction pipe; A drying device for drying the object to be dried; a drying gas introduction pipe for introducing a mixed gas containing the combustion gas generated in the combustion device and dilution air as a drying gas into the drying device; an exhaust pipe including an exhaust fan and configured to exhaust the drying gas from the drying device; a drying gas circulation pipe that introduces the drying gas from the drying device to the first dilution air introduction pipe and circulates it to the combustion device; a VOC concentration detector for detecting a concentration of volatile organic compounds contained in the drying gas in the drying device; a gas temperature detector for detecting a temperature of the drying gas in the drying device; A method for controlling a VOC concentration in a drying facility comprising: a VOC concentration determination unit controls the exhaust blower to adjust the flow rate of the drying gas exhausted from the drying device based on the concentration of the volatile organic compounds detected by the VOC concentration detector so that the concentration of the volatile organic compounds is maintained at a predetermined concentration, and controls the second air supplier to introduce air at the same flow rate as the flow rate of the drying gas exhausted from the drying device into the second dilution air introduction pipe; a temperature determination unit that adjusts the flow rate of fuel introduced from the fuel inlet pipe to the combustion device based on the temperature of the drying gas detected by the gas temperature detector so that the temperature of the drying gas is maintained at a predetermined temperature, and that controls the first air supplier to adjust the flow rate of combustion air introduced into the combustion air inlet pipe based on the fuel flow rate.

8. 8. The VOC concentration control method for drying equipment as described in claim 6 or 7, characterized in that the VOC concentration detector detects the concentration of volatile organic compounds contained in the drying gas at at least one location in the exhaust pipe, the drying gas circulation piping, and the drying device.

9. 9. The method for controlling a VOC concentration in a drying facility according to claim 6, wherein the gas temperature detector detects the temperature of the drying gas at least at one location in the drying gas inlet pipe, in the drying device, and in the drying gas circulation pipe.

Images