Superheated steam generator

Abstract

In systems that control the amount of water vapor generated by electricity, damage to the water vapor generation unit is prevented. [Solution] The system comprises a steam generation unit 2 that generates steam from water by induction heating a spiral first conductor tube 21, a superheated steam generation unit 3 that generates superheated steam from steam by induction heating a spiral second conductor tube 31, a control unit 61 that controls the amount of steam generated by the steam generation unit 2 according to the amount of electricity supplied to the steam generation unit 2, and a safety device 12 that prevents damage to the steam generation unit 2 or the superheated steam generation unit 3 based on the water pressure in the steam generation unit 2, the pressure or temperature of the steam in the steam generation unit 2, or the pressure or temperature of the superheated steam in the superheated steam generation unit 3.

Description

Technical Field

[0001] The present invention relates to an apparatus for generating superheated steam.

Background Art

[0002] As a conventional superheated steam generation apparatus, as shown in Patent Document 1, there are an induction heating type steam generation unit that heats water to generate steam, and an induction heating type superheated steam generation unit that heats the steam to generate superheated steam, and there is a device (power control method) that controls the amount of steam generated by the steam generation unit by the amount of electric power supplied to the steam generation unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In this superheated steam generation apparatus of the power control method, since the amount of heat per unit weight at which water becomes steam at a predetermined pressure is constant as a physical constant, by converting the amount of heat for the amount of steam to be generated into electric power and supplying it, high controllability of the amount of steam to be generated can be obtained.

[0005] However, in the power control method, since the electric power required for the desired amount of steam is input, the amount of steam is generated stably, but the discharge pressure is naturally adjusted according to the amount of steam generated. That is, the discharge pressure will increase as the load loss of the steam flow path increases, and in the worst case, the discharge pressure will increase until the device is destroyed.

[0006] Therefore, the present invention was made to solve the above problems, and its main objective is to prevent damage to the steam generation unit or the superheated steam generation unit in a system that controls the amount of steam generated by the amount of electricity. [Means for solving the problem]

[0007] In other words, the superheated steam generator according to the present invention is characterized by comprising: a steam generation unit that generates steam from water by induction heating a spiral first conductive tube; a superheated steam generation unit that generates superheated steam from the steam by induction heating a spiral second conductive tube; a control unit that controls the amount of steam generated by the steam generation unit by the amount of electricity supplied to the steam generation unit; and a safety device that prevents damage to the steam generation unit or the superheated steam generation unit based on the water pressure in the steam generation unit, the pressure or temperature of the steam in the steam generation unit, or the pressure or temperature of the superheated steam in the superheated steam generation unit.

[0008] In a power-controlled superheated steam generator, for example, if the evaporation temperature increases by 10°C from 120°C to 130°C, the pressure increases by approximately 1.36 times, from about 0.199 MPa to about 0.27 MPa, but the required enthalpy only increases by 1.0055 times, from 2706 kJ / kg to 2721 kJ / kg. While it is unlikely that a usage scenario would result in a 36% increase in pressure, even if such a scenario were to occur, the amount of steam generated would only fluctuate by 0.55%. Furthermore, if the evaporation temperature increases by 55°C from 120°C to 175°C, the pressure increases by approximately 4.49 times, from about 0.199 MPa to 0.892 MPa, but the required enthalpy only increases by 1.0251 times, from 2706 kJ / kg to 2774 kJ / kg, resulting in a fluctuation of 2.51% in the amount of steam generated. The superheated steam generator of the present invention has a steam generation stability set to, for example, within ±1%, and the safety device can be activated at a pressure of 0.35 MPa (enthalpy of approximately 2730 kJ / kg). At a pressure of 0.35 MPa, the enthalpy increases by approximately 2.0% compared to 99.63°C (pressure of 0.1 MPa and enthalpy of approximately 2675 kJ / kg), and the fluctuation in steam amount can be kept within ±1%. TIFF2026089634000002.tif32170

[0009] Furthermore, according to the present invention, even if the discharge pressure (discharge temperature corresponding to the discharge pressure) rises due to an increase in load loss in the steam flow path such as the first conductor pipe, damage to the steam generation unit or superheated steam generation unit can be prevented by the safety device. In addition, in the present invention, even if the strength of the conductor pipe decreases due to the rise in temperature, damage to the conductor pipe can be prevented by the safety device.

[0010] In terms of specific implementations of the safety device, it is desirable that the safety device has a discharge section for releasing at least one of the water, steam, or superheated steam to the outside.

[0011] In a specific alternative embodiment of the safety device, it is desirable that the safety device includes a pressure sensor that detects the pressure of at least one of the water, water vapor, or superheated water vapor, and a safety circuit that compares the boundary point pressure exceeding the range of fluctuation of the target amount of water vapor generated with the pressure detected by the pressure sensor, and outputs an alarm signal when the detected pressure becomes the boundary point pressure. In this configuration, the enthalpy value obtained from the saturated steam temperature is converted to the amount of steam generated, and an alarm is triggered at the boundary point pressure that exceeds the target fluctuation range of steam generation. In a power-controlled superheated steam generator, since there are no pressure reducing valves, steam flow adjustment valves, or electric proportional valves, the steam pressure is low, and a saturated steam pressure of 0.1 MPa, a saturated steam temperature of 99.63°C, and an enthalpy of 2675 kJ / kg can be considered as the minimum values. For example, if the target fluctuation range of steam generation is ±1.5%, the enthalpy will be 2675 × 1.03 = 2755 kJ / kg, and the saturated steam pressure corresponding to this enthalpy will be 0.6 MPa and the saturated steam temperature will be 158.84°C. In this case, the boundary point pressure will be set to, for example, 0.6 MPa. In other words, if the enthalpy of 2715 kJ / kg required for steam generation is converted to electricity and input, even if the discharge pressure drops to 0.6 MPa due to increased load pressure loss, the amount of steam generated will decrease by approximately 1.47%, or (2755 / 2715)-1 ≈ 0.0147. Conversely, when the load pressure loss is low at 0.1 MPa, it will increase by approximately 1.47%, or 1-(2675 / 2715) ≈ 0.0147. Therefore, the amount of steam generated will have a fluctuation range of approximately ±1.5%. Note that the actual input electricity will be a value that takes into account the amount of heat required to raise the water temperature and the efficiency of the equipment such as heat dissipation, but the above calculation is a calculation value for steam generated only.

[0012] In a specific alternative embodiment of the safety device, it is desirable that the safety device includes a temperature sensor for detecting the temperature of the steam or superheated steam, and a safety circuit that compares the temperature detected by the temperature sensor with a boundary point temperature that exceeds the range of fluctuation of the target amount of steam generated, and outputs an alarm signal when the detected temperature becomes the boundary point temperature. In this configuration, the enthalpy value obtained from the saturated vapor temperature is converted into the amount of water vapor produced, and an alarm is issued at the boundary point temperature when the fluctuation range of the target water vapor production exceeds this value. As mentioned above, if the fluctuation range of the target water vapor production is ±1.5%, the boundary point temperature will be set to, for example, 158.84°C.

[0013] In a specific alternative embodiment of the safety device, the safety device comprises a pressure sensor that detects the pressure of at least one of the water, steam, or superheated steam, and a safety circuit that outputs an alarm signal to shut off or limit the power supply to the steam generation unit based on the pressure detected by the pressure sensor, wherein the control unit preferably shuts off or limits the power supply to the steam generation unit based on the alarm signal.

[0014] In a specific alternative embodiment of the safety device, it is desirable that the safety device includes a temperature sensor for detecting the temperature of the steam or superheated steam, and a safety circuit for outputting an alarm signal to shut off or limit the power supply to the steam generation unit based on the temperature detected by the temperature sensor, and that the control unit shut off or limit the power supply to the steam generation unit based on the alarm signal.

[0015] In a specific alternative embodiment of the safety device, the safety device comprises a pressure sensor for detecting the pressure of at least one of the water, steam, or superheated steam; a temperature sensor for detecting the temperature of the steam or superheated steam; and a safety circuit for outputting an alarm signal to shut off or limit the power supply to the steam generation unit based on the pressure detected by the pressure sensor and the temperature detected by the temperature sensor, wherein the control unit preferably shuts off or limits the power supply to the steam generation unit based on the alarm signal.

[0016] It is desirable that the safety circuit outputs a warning signal before outputting the alarm signal. With this configuration, a warning signal is output before an alarm signal is output, which prompts the user to inspect the equipment on the user side into which the superheated steam generator 100 is incorporated.

[0017] The safety device is provided in the steam generation unit or between the steam generation unit and the superheated steam generation unit, and is intended to prevent damage to the steam generation unit or the superheated steam generation unit based on the pressure or temperature of the steam. With this configuration, it is possible to directly detect an increase in the pressure or temperature of the water vapor in the water vapor generation unit, and prevent damage to the water vapor generation unit or the superheated water vapor generation unit.

[0018] The safety device is provided in the superheated water vapor generation unit, and it is conceivable to prevent damage to the water vapor generation unit or the superheated water vapor generation unit based on the pressure or temperature of the superheated water vapor. With this configuration, it is possible to indirectly detect an increase in the pressure or temperature in the water vapor generation unit via the pressure or temperature of the superheated water vapor in the superheated water vapor generation unit, and prevent damage to the water vapor generation unit or the superheated water vapor generation unit.

[0019] The safety device is provided in the water vapor generation unit or the water supply pipe that supplies water to the water vapor generation unit, and it is conceivable to prevent damage to the water vapor generation unit or the superheated water vapor generation unit based on the pressure of the water. With this configuration, it is possible to indirectly detect an increase in the pressure or temperature in the water vapor generation unit via the pressure of the water in the water vapor generation unit or the water supply pipe, and prevent damage to the water vapor generation unit or the superheated water vapor generation unit.

Advantages of the Invention

[0020] According to the present invention configured as described above, it is possible to prevent damage to the water vapor generation unit or the superheated water vapor generation unit in an apparatus that controls the amount of generated water vapor by the amount of electric power.

Brief Description of the Drawings

[0021] [Figure 1] It is a diagram schematically showing the configuration of the superheated water vapor generation device of the first embodiment. [Figure 2] It is a diagram showing an example of the hollow conductor tube of the embodiment. [Figure 3] It is a diagram mainly showing the core configuration of each water vapor generation unit of the embodiment. [Figure 4] It is a diagram showing a modified example of the core configuration of each water vapor generation unit of the embodiment. [Figure 5] This diagram shows the wiring of the induction coils in each steam generation section of the same embodiment. [Figure 6] This diagram schematically shows the configuration of the control device of the same embodiment. [Figure 7] This figure schematically shows the configuration of the superheated steam generator according to the second embodiment. [Figure 8] This is a graph showing the operation of the superheated steam generator of the same embodiment. [Figure 9] This diagram schematically shows the configuration of a modified embodiment of a superheated steam generator. [Figure 10] This diagram schematically shows the configuration of a modified embodiment of a superheated steam generator. [Modes for carrying out the invention]

[0022] <First Embodiment> A first embodiment of the superheated steam generator according to the present invention will be described below with reference to the drawings.

[0023] The superheated steam generator 100 according to this embodiment generates superheated steam at temperatures exceeding 100°C (200°C to 2000°C) by heating water.

[0024] Specifically, the superheated steam generator 100, as shown in Figure 1, comprises a steam generation unit 2 (hereinafter referred to as the saturated steam generation unit 2) that heats water to generate saturated steam, and a superheated steam generation unit 3 that heats the saturated steam to generate superheated steam. Note that the power supply circuit is not shown in Figure 1.

[0025] <Configuration of saturated water vapor generation unit 2> The saturated steam generation unit 2 is of the induction heating type and includes a spirally wound cylindrical first conductive tube 21 and a magnetic flux generation mechanism 22 for induction heating the first conductive tube 21.

[0026] As shown in Figure 2, the first conductor tube 21 is formed from a single metal tube and has a spirally wound section, the first wound tube section 21a. A first inlet port P1 for introducing water is formed at one end, and a first outlet port P2 for releasing the generated saturated water vapor is formed at the other end. The first inlet port P1 is formed in the first inlet tube section 21b, which extends outward from one end of the first wound tube section 21a. The first outlet port P2 is formed in the first outlet tube section 21c, which extends outward from the other end of the first wound tube section 21a. This first conductor tube 21 serves as a container for generating saturated water vapor. The first conductor tube 21 can be made of austenitic stainless steel such as SUS304 or an alloy such as Inconel, which has high heat resistance and mechanical strength. In addition, the wound sections of the first conductor tube 21 are electrically connected to each other by welding or other means.

[0027] The magnetic flux generation mechanism 22 comprises an iron core 22a and an induction coil 22b wound along the iron core 22a. An AC power supply is connected to this induction coil 22b, supplying controlled power. The power frequency of the AC power supply is the commercial frequency of 50Hz or 60Hz. The induction coil 22b, powered by this AC power supply, becomes the primary coil, and as a result of being powered by the primary coil, an induced current flows through the first conductor tube 21, causing the first conductor tube 21 to become a single-turn secondary coil. Then, the first conductor tube 21 generates Joule heat, heating the water inside the first conductor tube 21 and generating saturated steam. The first conductor tube 21 is filled with water up to a predetermined height.

[0028] <Configuration of the superheated steam generation unit 3> The superheated steam generation unit 3 is of the induction heating type and includes a spirally wound cylindrical second conductive tube 31 and a magnetic flux generation mechanism 32 for induction heating the second conductive tube 31.

[0029] As shown in Figure 2, the second conductor tube 31 is formed from a single metal tube and has a spirally wound section, the second wound tube section 31a. A second inlet port P3 is formed at one end for introducing steam from the saturated steam generation section 2, and a second outlet port P4 is formed at the other end for releasing the generated superheated steam. The second inlet port P3 is formed in the second inlet tube section 31b, which extends outward from one end of the second wound tube section 31a. The second outlet port P4 is formed in the second outlet tube section 31c, which extends outward from the other end of the second wound tube section 31a. This second conductor tube 31 serves as a container for generating superheated steam. The second conductor tube 31 can be made of austenitic stainless steel such as SUS304 or an alloy such as Inconel, which have high heat resistance and mechanical strength. Furthermore, the second conductor tube 31 has adjacent winding portions that are electrically connected by welding or other means.

[0030] The second inlet port P3 is connected to either an external pipe for supplying steam from the saturated steam generation unit 2 to the second conductor pipe 31, or to the first outlet port P2 of the first conductor pipe 21 of the saturated steam generation unit 2. In other words, the first winding section 21a of the first conductor pipe 21 and the second winding section 31a of the second conductor pipe 31 are connected by a connecting pipe section CP, which consists of at least the first outlet section 21c and the second inlet section 31b. If there is external piping, that external piping also becomes part of the connecting pipe section CP. Furthermore, the second outlet port P4 is connected to an external pipe for supplying the generated superheated steam to the utilization side (e.g., a heat treatment chamber).

[0031] The magnetic flux generating mechanism 32 comprises an iron core 32a and an induction coil 32b wound along the iron core 32a. An AC power supply is connected to this induction coil 32b, supplying controlled power. The power frequency of the AC power supply is the commercial frequency of 50Hz or 60Hz. The induction coil 32b, powered by this AC power supply, becomes the primary coil, and as a result of being powered by the primary coil, an induced current flows through the second conductor tube 31, causing the second conductor tube 31 to become a single-turn secondary coil. Then, the second conductor tube 31 is heated by Joule heating, and the water vapor flowing inside is heated.

[0032] In the superheated steam generator 100 of this embodiment, as shown in Figures 3 and 4, in addition to the iron core 22a of the saturated steam generation unit 2 and the iron core 32a of the superheated steam generation unit 3, a common iron core 41 is provided, which serves as a common passage for the magnetic flux generated in the two iron cores 22a and 32a. The upper and lower ends of this common iron core 4 and the two iron cores 22a and 32a are connected by connecting iron cores 42 and 43, respectively, to form a single tripod iron core. This configuration makes it possible to reduce the overall dimensions of the iron core, and consequently, to make the entire device more compact. In other words, the superheated steam generator 100 of this embodiment uses a single tripod iron core to construct the saturated steam generation unit 2 and the superheated steam generation unit 3.

[0033] In Figures 3 and 4, the iron cores 22a, 32a, and 41 are arranged so that they are at the vertices of a triangle in a plan view, and the connecting iron cores 42 and 43 are bent at the common iron core 41 in a plan view. This reduces the distance between the two iron cores 22a and 32a, thereby reducing the overall width dimension of the tripod iron core and saving space.

[0034] Furthermore, in this embodiment, the induction coil 22b of the saturated steam generation unit 2 and the induction coil 32b of the superheated steam generation unit 3 are connected in a Scott connection that converts the three-phase AC power supply 5 into two single-phase ACs (see Figure 5). In other words, the superheated steam generator 100 of this embodiment has a Scott connection transformer having a single tripod core. The Scott connection transformer consists of a main transformer and a T-connector transformer, with the part corresponding to the saturated steam generation unit 2 being the main transformer and the part corresponding to the superheated steam generation unit 3 being the T-connector transformer.

[0035] Furthermore, as shown in Figure 5, a first control device 10 for controlling voltage or current is provided on one of the two phases on the input side of the main transformer. In Figure 5, the first control device 10, which is a semiconductor control element such as a thyristor, is provided on the V phase on the input side of the main transformer. In addition, a second control device 11 for controlling voltage or current is provided on one end of the primary coil (induction coil 32b) on the input side of the T-type transformer (the U phase side or the midpoint O side of the T-type primary coil). This second control device 11 also uses a semiconductor control element such as a thyristor, similar to the first control device 10. The control device 6 is configured to control the voltage applied to the primary coil (induction coil 22b) of the main transformer and the voltage applied to the primary coil (induction coil 32b) of the T-type transformer individually by controlling the first control device 10 and the second control device 11. The control device 6 is a computer having a CPU, memory, input / output interface, etc.

[0036] <Control of the superheated steam generator 100> The control device 6 controls the amount of saturated water vapor in the saturated water vapor generation unit 2 as follows:

[0037] As shown in Figure 6, the control device 6 includes a steam quantity control unit 61 that controls the amount of saturated steam generated by the saturated steam generation unit 2 based on the amount of electricity supplied to the saturated steam generation unit 2. The control device 6 also includes a relationship data storage unit 62 that stores relationship data showing the relationship between the amount of steam generated by the saturated steam generation unit 2 and the amount of electricity supplied to the saturated steam generation unit 2.

[0038] The related data stored in the related data storage unit 62 is obtained by measuring the amount of water vapor generated by the saturated water vapor generation unit 2 and the amount of electricity supplied to the saturated water vapor generation unit 2. This related data was measured under atmospheric pressure conditions, with the first outlet port P2 of the first conductor pipe 21 of the saturated water vapor generation unit 2 open to atmospheric pressure.

[0039] Furthermore, the water vapor amount control unit 61 acquires power data from the power meter 7, which measures the amount of power supplied to the saturated water vapor generation unit 2, and uses the aforementioned data to control the first control device 10 so that the amount of water vapor becomes predetermined. Specifically, the water vapor amount control unit 61 controls the first control device 10 so that the amount of power obtained by the power meter 7 becomes the target amount of power determined from the relevant data and the predetermined amount of water vapor. The power meter 7 is provided on one of the two phases on the input side of the main transformer that constitutes the saturated water vapor generation unit 2. In other words, in this embodiment, the saturated water vapor amount is controlled based solely on the amount of power obtained by the power meter 7.

[0040] In this superheated steam generator 100 that controls the amount of steam, the saturated steam generation unit 2 and the superheated steam generation unit 3 operate under atmospheric pressure conditions. Furthermore, there are no pressure reducing valves, steam volume adjustment valves, or electric proportional valves between the saturated steam generation unit 2 and the superheated steam generation unit 3, specifically in the connecting pipe section CP.

[0041] Furthermore, the control device 6 controls the first control device 10 to supply power to the saturated steam generation unit 2 to a value less than or equal to the maximum value or a value that prevents failure of any part, from startup until the above-mentioned steam quantity control. This control is performed until the water in the saturated steam generation unit 2 reaches just before it reaches 100°C, for example, 95°C, and then the control device 6 proceeds to the above-mentioned steam quantity control.

[0042] Furthermore, the control device 6 controls the temperature of the superheated steam generated by the superheated steam generation unit 3 as follows.

[0043] In the superheated steam generator 100 of this embodiment, the temperature of the superheated steam discharged from the second conductor pipe 31 of the superheated steam generation unit 3, or the piping temperature of the second discharge port P4 of the second conductor pipe 31, is detected by the temperature detector 8.

[0044] The control device 6 includes a temperature control unit 63 that controls the AC voltage applied to the induction coil 32b by inputting a control signal to the second control device 11 according to the deviation between the temperature detected by the temperature detector 8 and the target temperature of the superheated steam. This temperature control unit 63 provides feedback control to the temperature of the superheated steam heated by the second conductor tube 31 so that the deviation from the target temperature is less than ±1°C.

[0045] Furthermore, this embodiment includes a safety device 12 that prevents damage to the saturated steam generation unit 2 based on the pressure or temperature of the steam generated by the steam generation unit 2.

[0046] The safety device 12 shown in Figure 1 is provided between the saturated steam generation unit 2 or the steam generation unit 2 and the superheated steam generation unit 3, and has a steam discharge unit 12a that releases the steam generated by the saturated steam generation unit 2 to the outside.

[0047] The discharge section 12a is a safety valve that releases steam to the outside when the set pressure is reached. Specifically, the safety valve 12a releases the steam inside the first conductor pipe 21 to the outside when the steam pressure is less than 1 MPa (equivalent to 179.88°C). The superheated steam generator 100 of this embodiment falls under the category of a small once-through boiler or a simple once-through boiler as defined in the Boiler and Pressure Vessel Safety Regulations, and the safety valve 12a releases the steam inside the first conductor pipe 21 to the outside when the steam pressure is, for example, 0.4 MPa (specifically 0.4758 MPa (equivalent to 150°C)). The safety valve 12a is also provided in the first winding section 21a of the first conductor pipe 21, or in the connecting pipe section CP that connects the first winding section 21a of the first conductor pipe 21 and the second winding section 31a of the second conductor pipe 31. In this embodiment, the safety valve 12a is provided in the first outlet pipe section 21c in the connecting pipe section CP. Alternatively, the safety valve 12a may be provided in the upper part of the first winding pipe section 21a. In addition, the safety valve 12a may be provided in the second inlet pipe section 31b of the second conductor pipe 31.

[0048] With the superheated steam generator 100 configured in this way, the amount of steam can be stably generated by inputting the power required for the desired amount of steam, and as a result, the output amount of superheated steam at a predetermined temperature can be stabilized within an error range of ±1%. Furthermore, even if the discharge pressure rises due to an increase in load loss in the steam flow path, the safety valve 12a releases the steam inside the first conductor pipe 21 to the outside when the predetermined pressure is reached, thus preventing damage to the superheated steam generator, including the steam generation unit 2.

[0049] Steam heating allows for relatively uniform heating even of loads with complex shapes because the steam circulates around them. Furthermore, because it is an extremely low-oxygen environment, it is a safe heating method in terms of explosion-proof and flammability. In addition, since the amount of energy supplied by steam is basically proportional to the product of the steam temperature and the amount of steam, conventional boilers control the amount of steam by controlling the steam pressure with pressure reducing valves and adjusting the steam flow path area with proportional valves. Because control using such mechanical valves is difficult to control precisely and reproducibly, steam heating has been considered unsuitable for microfabrication. The power-controlled method of this embodiment solves these problems and realizes steam heating as a uniform and highly accurate heating method.

[0050] <Second Embodiment> Next, the superheated steam generator 100 according to the second embodiment will be described with reference to Figure 7. The superheated steam generator 100 of the second embodiment has the same configuration as the saturated steam generation unit 2 and the superheated steam generation unit 3 as the first embodiment, but the configuration of the safety device 12 is different.

[0051] Specifically, as shown in Figure 7, the safety device 12 includes a pressure sensor 12b that detects the pressure of the steam generated by the saturated steam generation unit 2, a temperature sensor 12c that detects the temperature of the steam generated by the saturated steam generation unit 2, and a safety circuit 12d that outputs an alarm signal to shut off or limit the power supply to the saturated steam generation unit 2 based on the pressure detected by the pressure sensor 12b and the temperature detected by the temperature sensor 12c. The pressure sensor 12b and the temperature sensor 12c are provided in the steam generation unit 2 or between the steam generation unit 2 and the superheated steam generation unit 3. Specifically, the pressure sensor 12b and the temperature sensor 12c are provided in the first winding section 21a of the first conductor pipe 21, or in the connecting pipe section CP that connects the first winding section 21a of the first conductor pipe 21 and the second winding section 31a of the second conductor pipe 31. The steam quantity control unit 61 then shuts off or limits the power supply to the saturated steam generation unit 2 based on the alarm signal output from the safety circuit 12d. Furthermore, the safety circuit 12d may also issue an alarm signal to the user based on the pressure detected by the pressure sensor 12b and the temperature detected by the temperature sensor 12c.

[0052] Here, the safety circuit 12d compares the pressure detected by the pressure sensor 12b with a threshold pressure of less than 1 MPa (for example, 0.35 MPa), and outputs an alarm signal if the detected pressure exceeds the threshold pressure. In addition, the safety circuit 12d compares the temperature detected by the temperature sensor 12c with a threshold temperature of less than 179.88°C, and outputs an alarm signal if the detected temperature exceeds the threshold temperature.

[0053] Thus, the safety circuit 12d has a threshold temperature (alarm temperature) or threshold pressure (alarm pressure) set based on the range of fluctuation in the target amount of water vapor generated (e.g., ±1%). This allows the user to take measures to reduce the pressure loss in the water vapor flow path. In the power control method, the stability of the amount of water vapor generated can be clearly indicated numerically, making it easier for the user to use.

[0054] Specifically, the safety circuit 12d may compare the boundary point pressure, which exceeds the fluctuation range of the target steam generation amount, with the pressure detected by the pressure sensor 12b, and output an alarm signal when the detected pressure reaches the boundary point pressure. The steam amount control unit 61 may also shut off or limit the power supply to the saturated steam generation unit 2 when an alarm signal is output from the safety circuit 12d. In a power-controlled superheated steam generator, since there is no pressure reducing valve, a valve to adjust the steam amount, or an electrically proportional valve, the steam pressure is low, and a saturated steam pressure of 0.1 MPa, a saturated steam temperature of 99.63 °C, and an enthalpy of 2675 kJ / kg can be considered as the minimum values. For example, if the fluctuation range of the target steam generation amount is ±1.5%, the enthalpy will be 2675 × 1.03 = 2755 kJ / kg, and the saturated steam pressure corresponding to this enthalpy will be 0.6 MPa and the saturated steam temperature will be 158.84 °C. In this case, the boundary point pressure will be set to, for example, 0.6 MPa. The boundary point pressure is set to a pressure lower than the set pressure of the discharge section 12a.

[0055] Furthermore, the safety circuit 12d may output a warning signal when the pressure detected by the pressure sensor 12b exceeds a predetermined threshold pressure (warning pressure, e.g., 0.30 MPa) that is lower than the boundary point pressure (e.g., 0.6 MPa) or the threshold pressure (alarm pressure, e.g., 0.35 MPa). Here, the warning pressure is set to a pressure that will not damage the user-side equipment into which the superheated steam generator 100 is incorporated. By outputting a warning signal based on this warning pressure, it is possible to prompt inspection of the user-side equipment into which the superheated steam generator 100 is incorporated.

[0056] Furthermore, the safety circuit 12d may compare the boundary point temperature, which exceeds the fluctuation range of the target water vapor generation amount, with the temperature detected by the temperature sensor 12c, and output an alarm signal when the detected temperature reaches the boundary point temperature. The water vapor amount control unit 61 may then shut off or limit the power supply to the saturated water vapor generation unit 2 when an alarm signal is output from the safety circuit 12d. As described above, if the fluctuation range of the target water vapor generation amount is ±1.5%, the boundary point temperature will be set to, for example, 158.84°C. The boundary point temperature is set to a temperature at which the corresponding saturated vapor pressure becomes smaller than the set pressure of the discharge unit 12a.

[0057] Furthermore, the safety circuit 12d may output a warning signal when the temperature detected by the temperature sensor 12c exceeds a predetermined threshold temperature (warning temperature) that is lower than the boundary point temperature (e.g., 158.84°C) or the threshold temperature (alarm temperature). Here, the warning temperature is set to a temperature that will not damage the user-side equipment into which the superheated steam generator 100 is incorporated. By outputting a warning signal based on the warning temperature in this way, it is possible to prompt inspection of the user-side equipment into which the superheated steam generator 100 is incorporated.

[0058] In addition to the heat required for the steam generation unit 2, there is also the heat required to raise the water temperature to 99.63°C. However, this is a unique value for each model, and there will be no significant fluctuations if the inlet water temperature range is specified. Furthermore, heat dissipation from piping, etc., also affects the temperature, but the temperature of the generated steam is a relatively low value of 100-180°C, and since insulation is provided, it is a small value compared to the latent heat of vaporization, and its effect is minor. By taking this heat dissipation into consideration when calculating the measured fluctuation values, it is possible to calculate the boundary point pressure or boundary point temperature accurately.

[0059] Furthermore, the safety device 12 may have a configuration that includes the discharge section 12a of the first embodiment, in addition to the configuration shown in Figure 7.

[0060] By configuring the safety device 12 to have a discharge section 12a in addition to the safety circuit 12d, the superheated steam generator 100 will perform a stepwise operation as shown in Figure 8, for example, by first outputting a warning signal (preliminary alarm) based on a warning pressure (warning temperature), second cutting off or limiting the power supply to the saturated steam generator 2 based on an alarm pressure (alarm temperature), and third releasing steam to the outside through the discharge section 12a.

[0061] Furthermore, the safety device 12 may not have a temperature sensor 12c in the configuration shown in Figure 7. In this case, the safety circuit 12d outputs an alarm signal to shut off or limit the power supply to the saturated steam generation unit 2 based on the pressure detected by the pressure sensor 12b.

[0062] Furthermore, the safety device 12 may not have a pressure sensor 12b in the configuration shown in Figure 7. In this case, the safety circuit 12d outputs an alarm signal to shut off or limit the power supply to the saturated steam generation unit 2 based on the temperature detected by the temperature sensor 12c.

[0063] <Other modified embodiments> The water vapor release section 12a of the safety device 12 may be a safety valve that opens when a set pressure is reached, or it may release water vapor to the outside in response to an external release signal. In this configuration, as shown in Figure 9, the safety circuit 12d may output an release signal to the water vapor release section 12a based on the pressure detected by the pressure sensor 12b or the temperature detected by the temperature sensor 12c.

[0064] Furthermore, as shown in Figure 10, the safety device 12 may be provided in the second winding pipe section 31a or the second outlet pipe section 31c of the superheated steam generation unit 3, or in the steam generation unit 2 or the water supply pipe 13 that supplies water to the steam generation unit 2. These configurations may also be added to the configuration in which the safety device 12 is provided in the first winding pipe section 21a or the connecting pipe section CP described above.

[0065] When the safety device 12 is installed in the superheated steam generation unit 3, as shown in Figure 10, it is conceivable to install the discharge unit 12a or pressure sensor 12b described above via the measuring tube 14 at the second outlet port P4 or its vicinity (for example, the straight pipe section) in the second outlet pipe section 31c of the second conductor pipe 31. Alternatively, the temperature sensor 12c described above may be installed at the second outlet port P4 or its vicinity (for example, the straight pipe section) in the second outlet pipe section 31c of the second conductor pipe 31. The safety operation of each part using the discharge unit 12a, pressure sensor 12b, or temperature sensor 12c is as described above. The safety operation using the temperature sensor 12c depends on the set temperature, as the superheated steam generation unit 3 is temperature-controlled. For example, if the set temperature of the superheated steam is 150°C, the temperature may rise as the load loss in the steam flow path increases, resulting in zero control input from the temperature control unit 63. Subsequently, if the temperature of the superheated steam gradually rises, a safety mechanism using the temperature sensor 12c will be activated.

[0066] Furthermore, if the safety device 12 is installed in the first inlet pipe section 21b or the water supply pipe 13 of the steam generation unit 2, it is conceivable to install the discharge section 12a or pressure sensor 12b described above in the first inlet port P1 or its vicinity (for example, the straight pipe section) of the first inlet pipe section 21b of the steam generation unit 2 or in the water supply pipe 13, as shown in Figure 10. The safety operation of each part using the discharge section 12a or pressure sensor 12b is as described above.

[0067] Furthermore, the position where the discharge section 12a is provided in the safety device 12 and the position where the pressure sensor 12b or temperature sensor 12c is provided may be different from each other. For example, the pressure sensor 12b or temperature sensor 12c may be provided in the steam generation unit 2 or between the steam generation unit 2 and the superheated steam generation unit 3, and the discharge section 12a may be provided in the steam generation unit 2 or the water supply pipe 13 to discharge water. Alternatively, the pressure sensor 12b or temperature sensor 12c may be provided in the superheated steam generation unit 3, and the discharge section 12a may be provided in the steam generation unit 2 or the water supply pipe 13 to discharge water. Furthermore, the pressure sensor 12b may be provided in the water supply pipe 13, and the discharge section 12a may be provided in the steam generation unit 2 or between the steam generation unit 2 and the superheated steam generation unit 3 to discharge steam.

[0068] The connecting pipe section CP of the above embodiment may be provided with a third introduction port for introducing steam, superheated steam, or another gas other than steam from the outside, or a third introduction pipe section having said third introduction port. For example, steam generated by an external boiler, superheated steam recycled after being introduced into a heat treatment chamber, or nitrogen gas can be introduced into this third introduction port. In this case, by providing the safety device 12 in the third introduction pipe section, the safety device 12 will be provided in the connecting pipe section CP.

[0069] The saturated steam generation unit 2 and the superheated steam generation unit 3 may use an induction heating method or an electric heating method. In this case, an AC power supply or a DC power supply is connected to both ends of the conductor pipes 21 and 31 through which the fluid flows, and the conductor pipes 21 and 31 are heated by Joule heating by passing an AC current or a DC current through them. In this case, the conductor pipes 21 and 31 can have various shapes, such as a spiral shape or a shape having multiple straight sections and multiple bent sections connecting two straight sections.

[0070] Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. [Explanation of Symbols]

[0071] 100...Superheated steam generator 2. Saturated steam generation section (steam generation section) 3. Superheated steam generation section 61. Water vapor quantity control unit (control unit) 12...Safety device 12a...Emission part 12b... Pressure sensor 12C... Temperature sensor 12d...Safety circuit

Claims

1. A steam generation unit that generates steam from water by induction heating of a spiral-shaped first conductive tube, A superheated steam generation unit generates superheated steam from the steam by inductively heating a spiral-shaped second conductive tube, A control unit that controls the amount of water vapor generated by the water vapor generation unit by the amount of electricity supplied to the water vapor generation unit, A superheated steam generator comprising a safety device for preventing damage to the steam generator or the superheated steam generator based on the pressure of the water in the steam generator, the pressure or temperature of the steam in the steam generator, or the pressure or temperature of the superheated steam in the superheated steam generator.

2. The superheated steam generator according to claim 1, wherein the safety device has a discharge section for discharging at least one of the water, the steam, or the superheated steam to the outside.

3. The aforementioned safety device is A pressure sensor for detecting the pressure of at least one of the water, water vapor, or superheated water vapor, The superheated steam generator according to claim 2, further comprising a safety circuit that compares a boundary point pressure exceeding the range of fluctuation of the target amount of steam generated with the pressure detected by the pressure sensor, and outputs an alarm signal when the detected pressure becomes the boundary point pressure.

4. The aforementioned safety device is A temperature sensor for detecting the temperature of the water vapor or the superheated water vapor, The superheated steam generator according to claim 2, further comprising a safety circuit that compares a boundary point temperature exceeding the range of fluctuation of the target amount of steam generated with the temperature detected by the temperature sensor, and outputs an alarm signal when the detected temperature becomes the boundary point temperature.

5. The aforementioned safety device is A pressure sensor for detecting the pressure of at least one of the water, water vapor, or superheated water vapor, The system includes a safety circuit that outputs an alarm signal to shut off or limit the power supply to the steam generation unit based on the pressure detected by the pressure sensor. The superheated steam generator according to claim 2, wherein the control unit shuts off or limits the power supply to the steam generation unit based on the alarm signal.

6. The aforementioned safety device is A temperature sensor for detecting the temperature of the water vapor or the superheated water vapor, The system includes a safety circuit that outputs an alarm signal to shut off or limit the power supply to the steam generation unit based on the temperature detected by the temperature sensor. The superheated steam generator according to claim 2, wherein the control unit shuts off or limits the power supply to the steam generation unit based on the alarm signal.

7. The aforementioned safety device is A pressure sensor for detecting the pressure of at least one of the water, water vapor, or superheated water vapor, A temperature sensor for detecting the temperature of the water vapor or the superheated water vapor, The system includes a safety circuit that outputs an alarm signal to shut off or limit the power supply to the steam generation unit based on the pressure detected by the pressure sensor and the temperature detected by the temperature sensor. The superheated steam generator according to claim 2, wherein the control unit shuts off or limits the power supply to the steam generation unit based on the alarm signal.

8. The superheated steam generator according to any one of claims 3 to 7, wherein the safety circuit outputs a warning signal in the stage prior to outputting the alarm signal.

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