HK1234135B - Superheated steam generator and processing method using the same - Google Patents

Description

Superheated steam generating device and treatment method using the same

Technical Field

The present invention relates to a superheated steam generating device for generating superheated steam from water and a treatment method using the superheated steam generating device.

Background Art

In recent years, superheated water vapor treatment devices that use superheated water vapor to clean, dry, or sterilize a treatment object have been studied.

As shown in Patent Document 1, the superheated steam treatment device includes a superheated steam generator that generates superheated steam and a treatment furnace supplied with the superheated steam generated by the superheated steam generator to clean, dry, or sterilize a treatment object accommodated in the treatment furnace.

However, for example, if the pressure in the treatment furnace is 1 atmosphere and the initial temperature of the workpiece is below 100°C, the superheated water vapor will liquefy and condense on the workpiece before the temperature of the workpiece rises above 100°C. Condensation on the workpiece is undesirable and undesirable.

Prior art literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-231367

Summary of the Invention

Therefore, the present invention has been made to solve the above-mentioned problems, and a main object of the present invention is to prevent condensation from occurring on an object to be treated when the object is treated with superheated water vapor.

That is, the present invention provides a superheated steam generating device including: a steam generating unit employing an induction heating method or an electric heating method for generating steam from water; a superheated steam generating unit employing an induction heating method or an electric heating method for generating superheated steam from water steam; a steam supply passage for supplying steam generated by the steam generating unit to the superheated steam generating unit; and a gas supply passage for supplying a gas other than the steam to the superheated steam generating unit. The superheated steam generating device is switchable between a first state in which the steam is supplied to the superheated steam generating unit and a second state in which the other gas is supplied to the superheated steam generating unit and the superheated steam generating unit functions as a gas heating unit. In addition to the first and second states, the superheated steam generating device is further switchable to a third state in which the steam and the other gas are supplied to the superheated steam generating unit and the superheated steam generating unit functions as a mixed gas heating unit.

According to this superheated steam generating device, in the first state, the superheated steam generating unit generates superheated steam. In the second state, the superheated steam generating unit functions as a gas heating unit, heating the other gas. Therefore, by heating the object with the heated other gas before using the superheated steam to treat it, it is possible to prevent the superheated steam from liquefying and causing condensation on the object. Furthermore, since the superheated steam generating unit functions as a gas heating unit, a separate heating device for heating the object is unnecessary, simplifying the system structure for preventing condensation on the object and enabling the system to be miniaturized. Furthermore, with this configuration, in addition to treating the object with superheated steam, other treatments can be performed. For example, when the other gas is air or nitrogen, oxidation or nitriding of the object can be performed.

Preferably, the superheated steam generating device further includes a steam flow rate regulator, disposed in the steam supply flow passage, for regulating the flow rate of the steam supplied to the superheated steam generating device. In the second state, the steam flow rate regulator stops supplying steam to the superheated steam generating device. With this configuration, the steam generating device generates steam in the second state, thereby enabling rapid switching from the second state to the first state.

Preferably, the superheated steam generator further includes a control device that controls the supply of power to the steam generator, and in the second state, the control device stops supplying power to the steam generator. This configuration reduces the power consumed by the steam generator in the second state.

Preferably, the superheated steam generating device further includes a steam flow rate regulator, disposed in the steam supply passage, for regulating the flow rate of the steam supplied to the superheated steam generating unit. In the third state, the steam flow rate regulator regulates the flow rate of the steam supplied to the superheated steam generating unit, thereby adjusting the mixing ratio of the steam and the other gas in the superheated steam generating unit. This configuration allows control of the treatment conditions of the treated object. For example, when the other gas is air or nitrogen, the degree of oxidation or nitridation of the treated object can be controlled.

Furthermore, the present invention provides a superheated steam generating device comprising: a steam generating unit employing an induction heating method or an electric heating method for generating steam from water; a superheated steam generating unit employing an induction heating method or an electric heating method for generating superheated steam from water steam; a steam supply passage for supplying steam generated by the steam generating unit to the superheated steam generating unit; and a gas supply passage for supplying a gas other than the steam to the superheated steam generating unit. The superheated steam generating device is switchable between a first state and a second state. The first state is a state in which the steam is supplied to the superheated steam generating unit. The second state is a state in which the other gas is supplied to the superheated steam generating unit and the superheated steam generating unit functions as a gas heating unit. The steam generating unit and the superheated steam generating unit are configured using a Scott connection transformer comprising a main transformer and a sub-transformer. The steam generating unit has a first heating metal body, which is heated by the output of the main transformer. The superheated steam generating unit includes a second heating metal body, which is inductively heated or electrically heated by the output of the sub-transformer. A first controller for controlling voltage or current is provided on one of the two phases on the input side of the main transformer, and a second controller for controlling voltage or current is provided on one end of the primary coil of the sub-transformer, which serves as the input side. The output voltage of the main transformer and the output voltage of the sub-transformer are independently controlled by the first and second controllers, respectively. The superheated steam generating device further includes a switching mechanism that switches between a first connection state and a second connection state. The first connection state is a state in which a midpoint terminal connected to the midpoint of the primary coil of the main transformer is connected to one end of the primary coil of the sub-transformer to form a Scott connection. The second connection state is a state in which the Scott connection is released and both ends of the primary coil of the sub-transformer, including the second controller, are connected to a three-phase AC power supply.

As specific structures of the steam generator and the superheated steam generator, the following structure can be considered: the steam generator and the superheated steam generator are configured using a Scott connection transformer consisting of a main transformer and a sub-transformer. The steam generator includes a first heating metal body, which is inductively heated or electrically heated by the output of the main transformer. The superheated steam generator includes a second heating metal body, which is inductively heated or electrically heated by the output of the sub-transformer.

In this configuration, in order to independently control the temperature of the water vapor generated by the water vapor generating unit and the temperature of the superheated water vapor generated by the superheated water vapor generating unit, it is preferred that a first controller for controlling voltage or current is provided on one of the two phases on the input side of the main transformer, and a second controller for controlling voltage or current is provided on one end of the primary coil serving as the input side of the sub-transformer. The output voltages of the main transformer and the sub-transformer are independently controlled by the first and second controllers.

Because the current flowing through the primary winding of the sub-transformer flows into the primary winding of the main transformer, the primary-side output control in the Scott connection transformer may fail to achieve zero output from the main transformer. For example, if water vapor is not output and the second heating element is heating other gases, the output of the first controller on the main transformer is controlled to zero and the output of the second controller on the sub-transformer is controlled to a high output. However, the current flowing from the primary winding of the sub-transformer into the primary winding of the main transformer causes the first heating element to heat. This can lead to overheating of the first heating element, which is a very dangerous problem.

In order to appropriately solve this problem, it is preferred that the superheated steam generating device further includes a switching mechanism that switches between a first connection state and a second connection state, wherein the first connection state is a state in which a midpoint terminal connected to the midpoint of the primary coil of the main transformer is connected to one end side terminal of the primary coil of the sub transformer to perform Scott connection, and the second connection state is a state in which the Scott connection is released and both side terminals of the primary coil of the sub transformer including the second controller are connected to a three-phase AC power supply.

With this configuration, the system can be operated in the first connection state (Scott connection) in the first state for generating superheated steam and the third state for heating a mixture of superheated steam and other gases. In the second state for heating only the other gases, the system can be operated in the second connection state (independent circuits for the sub-transformer side and the main transformer side). In the second connection state, the system can be operated while heating the other gases while maintaining the heat of the steam generator. Alternatively, the output of the first controller can be set to zero for continuous operation, heating only the other gases.

When the switching mechanism switches to the Scott connection state, if the input voltage of the three-phase AC power supply is set to E, the voltage applied to the primary coil of the sub-transformer including the second controller is E×(√3)/2. However, if the Scott connection is released by the switching mechanism and both side terminals of the primary coil of the sub-transformer including the second controller are connected to the three-phase AC power supply, the applied voltage becomes E. In other words, the applied voltage to the primary coil of the sub-transformer is multiplied by 2/(√3). Furthermore, until the second heating metal body reaches the target temperature, the second controller operates to achieve a high output, and the circuit current is also multiplied by approximately 2/(√3).

At this time, if the second controller is a device having a constant current control function, it can prevent a current exceeding a certain level from flowing through the primary coil of the sub-transformer, and can have a circuit protection function.

The present invention also provides a treatment method for treating an object to be treated using a superheated steam generating device, the superheated steam generating device comprising: a steam generating unit employing an induction heating method or an electric heating method for generating steam from water; a superheated steam generating unit employing an induction heating method or an electric heating method for generating superheated steam from water steam; a steam supply passage for supplying steam generated by the steam generating unit to the superheated steam generating unit; and a gas supply passage for supplying a gas other than the steam to the superheated steam generating unit. The treatment method comprises: a preceding step of supplying the other gas to the superheated steam generating unit and heating the other gas, thereby heating the object to be treated with the heated other gas; and a subsequent step of supplying the water vapor to the superheated steam generating unit after the preceding step to generate superheated steam, wherein the object to be treated, which has been heated in the preceding step, is treated with the superheated steam. In the subsequent step, the object to be treated is treated with a mixed gas consisting of the superheated steam and the other gas, as distinct from the treatment of the object to be treated with the superheated steam.

In addition, the present invention also provides a treatment method for treating a treatment object using the above-mentioned superheated water vapor generating device, the treatment method comprising: a front step of supplying the other gas to the superheated water vapor generating unit and heating the other gas, thereby heating the treatment object by the heated other gas; and a back step of supplying the water vapor to the superheated water vapor generating unit after the front step to generate superheated water vapor, thereby treating the treatment object that has been heated in the front step by the superheated water vapor.

According to the present invention having the above configuration, condensation on the object to be treated can be prevented by heating the object to be treated using another heated gas before treating the object to be treated using superheated water vapor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a diagram schematically showing the configuration of a superheated steam generator according to this embodiment.

FIG. 2 is a diagram showing an example of a hollow conductive tube according to the embodiment.

FIG. 3 is a diagram mainly showing the core structure of each steam generating unit in the same embodiment.

FIG. 4 is a diagram showing a modified example of the core structure of each steam generating unit in the same embodiment.

FIG. 5 is a diagram showing the connection of the induction coils of the steam generating units according to the embodiment.

FIG. 6 is a diagram schematically showing the configuration of a control device according to the same embodiment.

FIG. 7 is a diagram schematically showing a processing method according to the same embodiment.

FIG. 8 is a diagram showing the connection of the induction coils of the steam generating units according to the modified embodiment.

Description of Reference Numerals

100···Superheated steam generating device

L1···Water supply channel

L2···Saturated steam supply flow channel

L3···Gas supply flow channel

L4···Superheated steam supply flow channel

2. Saturated steam generating section (steam generating section)

3. Superheated steam generation unit

4···Steam flow control valve (steam flow control unit)

5···Gas flow control valve (gas flow control unit)

6···Processing Department

7···Control device

DETAILED DESCRIPTION

Hereinafter, one embodiment of the superheated steam generator of the present invention will be described with reference to the drawings.

The superheated steam generator 100 of this embodiment generates superheated steam by heating water. In addition to this superheated steam generation function, it also has a gas heating and superheating function for heating a gas other than water vapor. The other gas may be air, oxygen, nitrogen, argon, or any other gas other than water vapor, and various other gases may be used depending on the intended use.

As shown in FIG. 1 , the superheated steam generating device 100 includes: a steam generating unit 2 (hereinafter referred to as the saturated steam generating unit 2 ) for heating water to generate saturated steam; a superheated steam generating unit 3 for heating saturated steam to generate superheated steam; a steam supply flow path L2 (hereinafter referred to as the saturated steam supply flow path L2 ) for supplying the saturated steam generated by the saturated steam generating unit 2 to the superheated steam generating unit 3; and a gas supply flow path L3 for supplying a gas other than the saturated steam to the superheated steam generating unit 3.

The saturated steam generator 2 is, for example, an induction heating system or an electric heating system, and has a water inlet 21 for introducing water and a saturated steam outlet 22 for discharging saturated steam. Furthermore, a water supply flow path L1, which supplies water to the saturated steam generator 2 from a container (not shown) or the like, is connected to the water inlet.

The saturated water vapor generating unit 2 using an induction heating method may include: a hollow conductive tube 2T (refer to FIG. 2 ), which is formed in a spiral shape, for example, having a water inlet 21 and a saturated water vapor outlet 22; an induction coil (not shown), which is arranged on the inside or outside of the hollow conductive tube 2T and inductively heats the hollow conductive tube 2T; and an AC power supply (not shown), which applies an AC voltage to the induction coil. By applying the AC voltage to the induction coil, an induced current flows through the hollow conductive tube 2T, thereby generating Joule heat, thereby causing the water introduced into the hollow conductive tube 2T to change its state and become saturated water vapor.

The saturated steam generating unit 2 employing an electrical heating method may include: a hollow conductive tube 2T, formed, for example, in a spiral shape, having a water inlet 21 and a saturated steam outlet 22; and a DC power supply or an AC power supply (not shown) for applying a voltage to the hollow conductive tube 2T, causing a current to flow through the hollow conductive tube, thereby generating Joule heat and causing the water introduced into the hollow conductive tube 2T to change state and become saturated steam. Furthermore, in the case of an electrical heating method, the hollow conductive tube is not limited to a spiral shape and may also be formed, for example, in a straight tube shape.

In either method, the temperature of the saturated water vapor discharged from the saturated water vapor outlet 22 of the hollow conductive tube 2T is detected, and feedback control is performed on the voltage applied to the induction coil, the voltage applied to the hollow conductive tube 2T, or the current flowing through the hollow conductive tube 2T, thereby controlling the temperature of the saturated water vapor discharged from the saturated water vapor outlet 22 of the hollow conductive tube 2T. The temperature of the saturated water vapor can be detected by directly detecting the temperature of the saturated water vapor or indirectly detecting the temperature of the saturated water vapor by detecting the temperature of the hollow conductive tube 2T.

The superheated steam generator 3 is similar to the saturated steam generator 2 and is, for example, an induction heating method or an electric heating method, and has a saturated steam inlet 31 for introducing saturated steam and a superheated steam outlet 32 for discharging superheated steam.

The induction heating superheated steam generator 3 may include, for example, a spiral-shaped hollow conductive tube 3T (see FIG. 2 ), having a saturated steam inlet 31 and a superheated steam outlet 32; an induction coil (not shown) disposed inside or outside the hollow conductive tube 3T for induction heating the hollow conductive tube 3T; and an AC power supply (not shown) for applying an AC voltage to the induction coil. The application of the AC voltage to the induction coil causes an induced current to flow through the hollow conductive tube 3T, thereby generating Joule heat and causing the saturated steam introduced into the hollow conductive tube 3T to change state and become superheated steam.

The superheated steam generator 3 employing an electrical heating method may include: a hollow conductive tube 3T formed, for example, in a spiral shape, having a saturated steam inlet 31 and a superheated steam outlet 32; and a DC or AC power supply (not shown) that applies a voltage to the hollow conductive tube 3T, causing current to flow through the hollow conductive tube 3T, thereby generating Joule heat and causing the saturated steam introduced into the hollow conductive tube 3T to change state and become superheated steam. In either embodiment, the temperature of the superheated steam discharged from the superheated steam outlet 32 of the hollow conductive tube 3T is controlled by controlling the voltage applied to the hollow conductive tube 3T or the current flowing through the hollow conductive tube 3T. Furthermore, in the case of an electrical heating method, the hollow conductive tube 3T is not limited to a spiral shape and may also be a straight hollow conductive tube, for example.

In either method, the temperature of the superheated water vapor discharged from the superheated water vapor outlet 32 of the hollow conductive tube 3T is detected, and feedback control is performed on the voltage applied to the induction coil, the voltage applied to the hollow conductive tube 3T, or the current flowing through the hollow conductive tube 3T, thereby controlling the temperature of the superheated water vapor discharged from the superheated water vapor outlet 32 of the hollow conductive tube 3T. The superheated water vapor temperature can be detected by directly detecting the temperature of the superheated water vapor or indirectly detecting the temperature of the superheated water vapor by detecting the temperature of the hollow conductive tube 3T.

In addition, in the case of induction heating, if the frequency of the applied AC voltage is set to a commercial frequency of 50 Hz or 60 Hz, the current penetration is deep, so the temperature detection through the outer surface of the hollow conductor tubes 2T and 3T can obtain the same value as the temperature detection of the inner surface, so even indirect detection can achieve high-precision steam temperature detection.

In this embodiment, as shown in Figures 3 and 4 , magnetic circuit cores 101 and 102 are disposed at the center of the induction coil 2C of the saturated steam generator 2 and the induction coil 3C of the superheated steam generator 3. This allows the magnetic flux generated by the induction coils 2C and 3C to circulate efficiently, thereby efficiently directing the magnetic flux into each hollow conductor tube 2T and 3T. Furthermore, in addition to the magnetic circuit core 101 of the saturated steam generator 2 and the magnetic circuit core 102 of the superheated steam generator 3, a common core 103 is provided. This common core 103 serves as a common path for the magnetic flux generated by the two magnetic circuit cores 101 and 102. Connecting cores 104 and 105 connect the common core 103 and the two magnetic circuit cores 101 and 102 above and below, respectively. This configuration reduces the overall size of the core, further miniaturizing the overall device. Furthermore, in Figures 3 and 4, the cores are arranged so that they are located at the vertices of a triangle when viewed from above, and the connecting cores 104 and 105 are bent so that the common core 103 serves as the bending point when viewed from above. This reduces the distance between the two magnetic circuit cores 101 and 102, thereby reducing the overall width of the core and achieving space saving.

The induction coil 2C of the saturated steam generator 2 and the induction coil 3C of the superheated steam generator 3 are Scott-connected (see FIG5 ). Specifically, the saturated steam generator 2 and the superheated steam generator 3 are configured using a Scott-connected transformer consisting of a main transformer and a teaser transformer.

The output of the main transformer induction heats or conducts heat to the hollow conductive tube 2T (first heating metal body) of the saturated steam generator 2. The output of the sub-transformer induction heats or conducts heat to the hollow conductive tube 3T (second heating metal body) of the superheated steam generator 3.

Furthermore, a first controller 81 is provided on one of the two phases on the input side of the main transformer (the V phase of the three-phase AC power supply 10 in FIG5 ). The first controller 81 controls the voltage or current. A second controller 82 is provided on one end of the primary coil (induction coil 3C) on the input side of the sub-transformer (the U phase of the three-phase AC power supply 10 in FIG5 ). The second controller 82 controls the voltage or current. Here, the first controller 81 and the second controller 82 are constructed using semiconductor control elements such as thyristors. Furthermore, the output voltages of the main transformer and the sub-transformer are independently controlled by the first controller 81 and the second controller 82, respectively.

One end of the saturated steam supply flow path L2 is connected to the saturated steam outlet 22 of the saturated steam generator 2, and the other end is connected to the superheated steam inlet 31 of the superheated steam generator 3. The saturated steam supply flow path L2 is formed, for example, by a connecting pipe. Alternatively, one of the hollow conductive tubes 2T and 3T may be integrally provided with the function of the connecting pipe, and the saturated steam outlet 22 of the saturated steam generator 2 and the superheated steam inlet 31 of the superheated steam generator 3 may be connected by, for example, an insulating joint.

Furthermore, a steam flow rate regulator 4 (hereinafter referred to as the saturated steam flow rate regulator 4) is provided in the saturated steam supply passage L2 to regulate the flow rate of saturated steam supplied to the superheated steam generator 3. The saturated steam flow rate regulator 4 in this embodiment is a first flow rate regulator valve. Furthermore, a control signal is input to the first flow rate regulator valve 4 by a control device 7, described later, to control its valve opening. Alternatively, a flow meter may be provided in the saturated steam supply passage L2.

One end of the gas supply channel L3 is connected to a supply source of another gas (such as air or nitrogen), and the other end is connected to the downstream side of the first flow control valve 4 on the saturated steam supply channel L2 (on the side of the superheated steam generator 3) or to the superheated steam generator 3. When the gas supply channel L3 is connected to the saturated steam supply channel L2, a gas inlet port is formed in the connecting pipe constituting the gas supply channel L3. Furthermore, when the gas supply channel L3 is connected to the superheated steam generator 3 (see FIG. 1 ), a gas inlet port 33 (not shown in FIG. 2 ) is formed in the superheated steam generator 3. Furthermore, when the gas inlet port 33 is formed in the superheated steam generator 3, it is preferably formed upstream of the hollow conductive tube 3T (on the side of the saturated steam inlet port 31) to consider the heating efficiency of other gases.

Furthermore, a gas flow rate regulator 5 is provided in the gas supply passage L3. The gas flow rate regulator 5 regulates the flow rate of other gases supplied to the superheated steam generator 3. In this embodiment, the gas flow rate regulator 5 is a second flow rate regulator valve. Furthermore, a control signal is input to the second flow rate regulator valve 5 by a control device 7, described later, to control its valve opening. Alternatively, a flow meter may be provided in the gas supply passage L3.

In addition, in the present embodiment, the superheated steam or other heated gas generated by the superheated steam generating unit 3 is supplied to the processing unit 6 , and the processing unit 6 processes the object W to be processed.

The processing unit 6 performs heat treatment (e.g., cleaning, drying, calcining, or sterilizing) on the object W using superheated water vapor or other gases. The processing unit 6 includes: an object storage unit 61 that houses the object W and forms a sealed or substantially sealed space; a superheated water vapor inlet 62 provided in the object storage unit 61 for introducing superheated water vapor; a condensed water outlet 63 for discharging condensed water generated in the object storage unit 61; and an outlet 64 for discharging used steam or other gases that have passed through the object storage unit 61. The superheated water vapor inlet 62 of the processing unit 6 is connected to the superheated water vapor outlet 32 of the superheated water vapor generator 3 via a superheated water vapor supply flow path L4. On/off valves are provided in the flow paths connecting the condensed water outlet 63 and the outlet 64.

The superheated steam generating device 100 is configured to be switchable between a first state, a second state, and a third state. The first state is a state in which only saturated steam is supplied to the superheated steam generating section 3. The second state is a state in which only other gases are supplied to the superheated steam generating section 3, and the superheated steam generating section 3 functions as a gas heating section. The third state is a state in which both saturated steam and other gases are supplied to the superheated steam generating section 3, and the superheated steam generating section 3 functions as a mixed gas heating section.

Here, the superheated steam generating device 100 switches to any one of the first, second, and third states by controlling the control device 7 that controls the saturated steam generating unit 2, the superheated steam generating unit 3, the first flow regulating valve 4, and the second flow regulating valve 5.

The control device 7 is physically equipped with a CPU, memory, an A/D converter, and a D/A converter. As shown in Figure 6 , the control device 7 functionally includes a first heating temperature control unit 71 for controlling the heating temperature of the saturated steam generator 2 (hereinafter referred to as the first heating temperature); a second heating temperature control unit 72 for controlling the heating temperature of the superheated steam generator 3 (hereinafter referred to as the second heating temperature); a first flow control valve control unit 73 for controlling the first flow control valve 4; and a second flow control valve control unit 74 for controlling the second flow control valve 5. Furthermore, the control device 7 includes a processed material temperature acquisition unit 75 for acquiring the temperature of the processed material W housed in the processing unit 6 or the temperature within the processing unit 6. The control device 7 is connected to various components, including the saturated steam generator 2 and the superheated steam generator 3, but illustration of these connections is omitted in Figure 1 .

Hereinafter, the operation of the superheated steam generator 100 according to the present embodiment will be described with reference to FIG. 7 , also serving as a description of each portion.

First, when a user operates the superheated steam generator 100 , water in a container (not shown) is supplied to the saturated steam generating unit 2 by, for example, a water supply pump or the like.

At this time, the first heating temperature control unit 71 controls the first heating temperature so that the saturated steam generated by the saturated steam generating unit 2 reaches a predetermined temperature. In this embodiment, the temperature of the hollow conductive tube 2T of the saturated steam generating unit 2 is set to the first heating temperature.

Specifically, the first heating temperature control unit 71 obtains a measurement value from a first temperature sensor T1 provided in the hollow conductor tube 2T or the saturated water vapor supply flow channel L2 of the saturated water vapor generating unit 2, and controls the magnitude of the AC voltage applied to the induction coil 2C of the saturated water vapor generating unit 2 according to the measurement value, thereby controlling the first heating temperature to, for example, 100 to 140°C.

Furthermore, in order to make the measured value closer to the temperature of saturated steam, it is preferred that the first temperature sensor T1 is provided on the downstream side of the hollow conductive tube 2T of the saturated steam generating unit 2 , or at or near the saturated steam outlet 22 .

Furthermore, while the saturated steam generator 2 is generating saturated steam, the first flow rate regulating valve control unit 73 controls the first flow rate regulating valve 4 to a zero valve opening, that is, to a closed state. Consequently, the superheated steam generator 100 is in a state where the saturated steam generator 2 is generating saturated steam and is in a standby state, in which the supply of saturated steam is stopped.

In this standby state, the second flow rate regulating valve control unit 74 opens the second flow rate regulating valve 5 to supply other gas to the superheated steam generating unit 3 from the gas supply flow path L3 .

At this time, the second heating temperature control unit 72 controls the second heating temperature so that the other gas heated by the superheated steam generator 3 reaches a predetermined temperature. In this embodiment, the temperature of the hollow conductor tube 3T of the superheated steam generator 3 is set to the second heating temperature.

Specifically, the second heating temperature control unit 72 obtains a measurement value from a second temperature sensor T2 provided in the hollow conductive tube 3T of the superheated steam generating unit 3 or the superheated steam supply flow path L4, and controls the magnitude of the AC voltage applied to the induction coil 3C of the superheated steam generating unit 3 based on the measurement value, thereby controlling the second heating temperature to, for example, above 100°C.

The second heating temperature when heating the other gas may be any temperature that can heat the object W to such an extent that condensation does not occur on the object W when the superheated water vapor is supplied. Furthermore, in order to make the measured value closer to the temperature of the superheated water vapor, the second temperature sensor T2 is preferably provided on the downstream side of the hollow conductive tube 3T of the superheated water vapor generating unit 3, or at or near the superheated water vapor outlet 32.

As a result, the first flow control valve 4 is closed, the second flow control valve 5 is open, and the superheated steam generator 3 enters the second state, where the superheated steam generator 3 functions as a gas heating unit for heating other gases. In this second state, the pre-process of heating (preheating) the workpiece W accommodated in the processing unit 6 is performed.

The processed object temperature obtaining unit 75 of the control device 7 obtains a measurement value from the third temperature sensor T3, which measures the temperature of the processed object W housed in the processing unit 6 or the temperature within the processing unit 6. Furthermore, the processed object temperature obtaining unit 75 determines whether the measurement value from the third temperature sensor T3 reaches a predetermined temperature (a temperature at which condensation does not occur on the processed object W when superheated water vapor is supplied).

When the processed object temperature obtaining unit 75 determines that the measured value from the third temperature sensor T3 is above the specified temperature, the second flow regulating valve control unit 74 controls the second flow regulating valve 5 to a closed state, and the first flow regulating valve control unit 73 opens the first flow regulating valve 4 to supply saturated water vapor from the saturated water vapor supply flow channel L2 to the superheated water vapor generating unit 3.

Furthermore, the first flow control valve control unit 73 and the second flow control valve control unit 74 may switch the opening and closing of the first flow control valve 4 and the second flow control valve 5 in accordance with a switching signal input from a user, independently of the determination of the process object temperature obtaining unit 75. Furthermore, the first flow control valve control unit 73 and the second flow control valve control unit 74 may switch the opening and closing of the first flow control valve 4 and the second flow control valve 5 in response to a predetermined time elapse signal indicating that a predetermined time has elapsed since the second state was achieved, obtained by a timer or the like.

At this time, the second heating temperature control unit 72 obtains a measurement value from a second temperature sensor T2 provided in the hollow conductive tube 3T of the superheated steam generator 3 or in the superheated steam supply flow path L4. Based on this measurement value, the second heating temperature is controlled so that the superheated steam generated by the superheated steam generator 3 reaches a predetermined temperature. Specifically, the second heating temperature is controlled to a set temperature of the superheated steam generated by the superheated steam generator 3 or a temperature around the set temperature, here, for example, 200 to 1200°C.

Thus, the first flow control valve 4 is in the open state, the second flow control valve 5 is in the closed state, and the superheated steam generating device 100 enters the first state where the superheated steam generating unit 3 generates superheated steam. In this first state, a post-process is performed, wherein the object W accommodated in the processing unit 6 is subjected to heat treatment (e.g., cleaning, drying, calcining, or sterilization).

Furthermore, when switching from the second state (the standby state) serving as a gas supply state to the first state serving as a saturated steam supply state, as shown in FIG7 , the first flow control valve control unit 73 controls the first flow control valve 4 to gradually open, gradually increasing its valve opening from zero to a predetermined opening. Thus, from the point of switching from the standby state to the saturated steam supply state until the valve opening of the first flow control valve 4 reaches the predetermined opening, an initial operation is achieved in which the saturated steam supply amount gradually increases. From the point in time when the valve opening reaches the predetermined opening, a stable operation is achieved in which the saturated steam supply amount remains constant. Furthermore, post-processing is performed within the predetermined processing time.

Next, the operation at the end of the post-process will be described.

The superheated steam generator 100 of this embodiment stops supplying saturated steam to the superheated steam generator 3 after a predetermined time has elapsed from the point in time when an automatic or manual operation for switching from the saturated steam supply state to the standby state is performed. Furthermore, when the operation for switching from the saturated steam supply state to the standby state is performed, the power supply to the induction coil of the superheated steam generator 3 is stopped.

Here, the operation for switching from the saturated steam supply state to the standby state is, for example, a user inputting a switching signal using an external input device, or a timer outputting a predetermined time elapse signal indicating that a predetermined time has passed in the saturated steam supply state.

More specifically, in this embodiment, when an operation is performed to switch from the saturated steam supply state to the standby state, the first flow control valve control unit 73 receives, for example, the switching signal or the predetermined time elapsed signal, and maintains the first flow control valve 4 in an open state for a predetermined time period from the time the signal is received. During the predetermined time period, saturated steam is supplied from the saturated steam generator 2 to the superheated steam generator 3. This cools the superheated steam generator 3, which has reached a high temperature at the end of the subsequent process, with the saturated steam. This cooling of the superheated steam generator 3 to the set temperature for the standby state prevents damage to the superheated steam generator 100.

As described above, the object W heat-treated in the pre-process and post-process is taken out from the processing unit 6. In addition, after the untreated object W is stored in the processing unit 6, the pre-process and post-process are performed in the same manner as described above.

Furthermore, in the superheated steam generating device 100 of this embodiment, in a later step, the first flow control valve controller 73 opens the first flow control valve 4, and the second flow control valve controller 74 opens the second flow control valve 5, thereby supplying both saturated steam and other gases to the superheated steam generating unit 3. In this manner, by adjusting the flow rates of the saturated steam and other gases supplied to the superheated steam generating unit 3, the mixing ratio of the mixed gas composed of the superheated steam and other gases can be adjusted. Thus, when mixing and heating the saturated steam and other gases, it is preferable that the hollow conductive tube be spirally shaped in order to ensure that the mixing path is as long as possible and that the mixing is uniform.

In the post-process, by supplying both saturated steam and another gas to the superheated steam generator 3, a treatment different from that using superheated steam can be performed. For example, when the other gas is air or nitrogen, oxidation or nitridation of the treatment object W can be performed. Furthermore, by adjusting the mixing ratio, the degree of oxidation or nitridation of the treatment object W can be controlled.

According to the superheated steam generating device 100 configured in this manner, in the first state, the superheated steam generating unit 3 generates superheated steam, and in the second state, the superheated steam generating unit 3 functions as a gas heating unit to heat another gas. Therefore, by heating the object W with the heated other gas before the object W is treated with the superheated steam, it is possible to prevent the superheated steam from liquefying and condensing on the object W. Furthermore, since the superheated steam generating unit 3 functions as a gas heating unit, a separate heating device for heating the object W is unnecessary, simplifying the system configuration for preventing condensation on the object W and reducing the size of the system.

In addition, the present invention is not limited to the above-described embodiment.

For example, in the above embodiment, the second state is achieved by having the first flow control valve control unit 73 close the first flow control valve 4. However, the second state may also be achieved by having the first heating temperature control unit 71 stop supplying power to the induction coil of the saturated steam generator 2. In this case, the first flow control valve 4 can be either closed or open, but if the first flow control valve 4 is closed, it is possible to prevent other gases from flowing back into the saturated steam generator 2.

Furthermore, in the above-described embodiment, the superheated steam generating unit 3 is configured to receive the saturated steam generated by the saturated steam generating unit 2 provided in the preceding stage. However, in a case where the saturated steam generating unit 2 further heats the saturated steam to generate superheated steam, the superheated steam generating unit 3 may be configured to receive the superheated steam and further heat the received superheated steam to generate superheated steam of a desired temperature to be supplied to the superheated steam utilizing unit.

In addition to the configuration of the aforementioned embodiment, the superheated steam generator 100 may also include a return flow channel for returning used steam or other gas that has passed through the processing section 6 to the superheated steam generator 3. One end of the return flow channel is connected to the processing section 6 (e.g., the outlet of the processed object storage section), and the other end is connected to the downstream side of the flow control valve of the saturated steam supply flow channel L2 (on the superheated steam generator 3 side), the gas supply flow channel L3, or the superheated steam generator 3. By reusing the used steam or other gas in this manner, heat loss can be suppressed.

Furthermore, as shown in FIG8 , the superheated steam generating device 100 may also include a switching mechanism 9 for switching between a first connection state in which the primary coil of the main transformer (the induction coil 2C) and the primary coil of the sub-transformer (the induction coil 3C) are Scott-connected and a second connection state in which the induction coil 2C and the induction coil 3C are each used as an independent circuit.

The first connection state is a Scott connection state in which the midpoint terminal 2M, connected to the midpoint of the primary coil (induction coil 2C) of the main transformer, is connected to one end terminal 3E of the primary coil (induction coil 3C) of the sub-transformer. Meanwhile, the second connection state is a state in which the Scott connection is released and both side terminals of the primary coil (induction coil 3C) of the sub-transformer, including the second controller 82, are connected to the three-phase AC power supply 10 (U phase and V phase in FIG8 ). Furthermore, in the second connection state, both side terminals of the primary coil (induction coil 2C) of the main transformer remain connected to the V phase and W phase of the three-phase AC power supply 10.

The switching mechanism 9 is formed using, for example, an electromagnetic contactor or a semiconductor switching element and is controlled by the control device 7. In this configuration, the second controller 82 has a constant current control function for controlling the current flowing through the primary coil (induction coil 3C) of the sub-transformer to a constant value or less.

In the first state, in which superheated steam is generated, and in the third state, in which a mixture of superheated steam and other gases is heated, the switching mechanism 9 switches to the first connection state (Scott connection state). In the second state, in which only other gases are heated, the switching mechanism 9 switches to the second connection state (a state in which the sub-transformer side circuit and the main transformer side circuit are independent circuits). Furthermore, in the second connection state, while the second controller 82 controls the current flowing through the induction coil 3C to heat the other gases for operation, the first controller 81 controls the current flowing through the induction coil 2C, allowing the saturated steam generating unit 2 to maintain its temperature and standby.

The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

The technical features described in the various implementation modes (examples) of the present invention can be combined with each other to form new technical solutions.

Claims (7)

1. A superheated steam generating device, characterized in that, The superheated steam generating device includes: A steam generation unit that uses induction heating or electric heating to generate steam from water; A superheated steam generation unit that uses induction heating or electric heating to generate superheated steam from water vapor; A steam supply channel supplies steam generated by the steam generation unit to the superheated steam generation unit; and The gas supply channel supplies a gas different from the water vapor to the superheated steam generation unit. The superheated steam generating device can be switched to a first state or a second state. The first state is when water vapor is supplied to the superheated steam generating unit, and the second state is when other gases are supplied to the superheated steam generating unit and the superheated steam generating unit functions as a gas heating unit. In addition to the first and second states, the superheated steam generating device can also be switched to a third state, in which the superheated steam generating unit supplies the steam and the other gases and functions as a mixed gas heating unit. 2. The superheated steam generating device according to claim 1, characterized in that, The superheated steam generating device further includes a steam flow regulating unit, which is disposed on the steam supply channel and is used to regulate the flow rate of the steam supplied to the superheated steam generating unit. In the second state, the steam flow regulating unit stops supplying steam to the superheated steam generating unit. 3. The superheated steam generating device according to claim 1, characterized in that, The superheated steam generating device also includes a control device that controls the supply of electricity to the steam generating unit. In the second state, the control device stops supplying power to the steam generating unit. 4. The superheated steam generating device according to claim 1, characterized in that, The superheated steam generating device further includes a steam flow regulating unit, which is disposed on the steam supply channel and is used to regulate the flow rate of the steam supplied to the superheated steam generating unit. In the third state, the steam flow rate regulating unit adjusts the flow rate of the steam supplied to the superheated steam generating unit, thereby adjusting the mixing ratio of the steam and the other gases in the superheated steam generating unit. 5. The superheated steam generating device according to claim 1, characterized in that, The steam generation unit and the superheated steam generation unit are constructed using a Scotch-connected transformer consisting of a main transformer and an auxiliary transformer. The steam generation unit has a first heating metal body, which is subjected to induction heating or electrical heating via the output of the main transformer. The superheated steam generating unit has a second heating metal body, which is subjected to induction heating or electrical heating via the output of the secondary transformer. A first controller for controlling voltage or current is provided on one of the two phases on the input side of the main transformer. A second controller for controlling voltage or current is provided at one end of the primary coil, which serves as the input side, of the secondary transformer. The output voltage of the main transformer and the output voltage of the secondary transformer can be independently controlled by the first controller and the second controller, respectively. The superheated steam generating device further includes a switching mechanism that switches between a first connection state and a second connection state. The first connection state is a state in which the midpoint terminal connected to the midpoint of the primary coil of the main transformer is connected to one end terminal of the primary coil of the secondary transformer to form a Scott connection. The second connection state is a state in which the Scott connection is disconnected and both ends of the primary coil of the secondary transformer, including the second controller, are connected to a three-phase AC power supply. 6. The superheated steam generating device according to claim 5, characterized in that, The second controller has a constant current control function. 7. A treatment method comprising treating a material using a superheated steam generating apparatus according to any one of claims 1 to 6, characterized in that, The processing method includes: In the preceding process, the other gas is supplied to the superheated steam generation unit and heated, and the workpiece is heated by the heated other gas; and In the subsequent process, after the preceding process, steam is supplied to the superheated steam generation unit to generate superheated steam, which is then used to treat the workpiece that has been heated in the preceding process. In the subsequent process, unlike the treatment of the workpiece using the superheated steam, the workpiece is treated using a mixture of the superheated steam and the other gases.