Method for estimating density of superheated water vapor and method for measuring volume flow rate of superheated water vapor

Abstract

The invention provides a method for estimating the density of superheated steam and a method for measuring the volume flow rate of superheated steam. The method for estimating the density of superheated steam makes it possible to easily grasp the density of superheated steam at a predetermined temperature and a predetermined pressure as an object. In a virtual density calculation step (S11), a virtual density (rho ntp) is calculated from a state equation of an ideal gas on the basis of conditions of a temperature (Tntp) and a pressure (Pntp) in a standard state and a molecular weight (M) of water. The virtual density [rho] ntp is a virtual density of superheated steam in a standard state in which the superheated steam is assumed to be present in the standard state while being regarded as a desired gas. In the density estimation step (S12), the density ([rho] est) of the superheated steam in a state of a predetermined temperature (Tpd) and a predetermined pressure (Ppd) is calculated on the basis of the Boyle-Ear law using the virtual density ([rho] ntp) calculated in the virtual density calculation step (S11), thereby estimating the density ([rho] est) of the superheated steam in a state of the predetermined temperature (Tpd) and the predetermined pressure (Ppd).

Description

Technical Field

[0001] This invention relates to a method for estimating the density of superheated steam and a method for measuring the volumetric flow rate of superheated steam. Background Technology

[0002] It is known to perform heat treatment of a workpiece by heating it with superheated steam (see, for example, Patent Document 1). Patent Document 1 discloses a steam reflow oven apparatus 1 that uses superheated steam continuously supplied to a heating furnace 2 to heat the workpiece brought into the heating furnace 2. The temperature of the superheated steam continuously supplied to the heating furnace 2 is measured using only a temperature sensor 4.

[0003] When heat-treating a workpiece using superheated steam, depending on the type of heat treatment, it is sometimes necessary to have a more accurate grasp of the atmosphere within the heat treatment chamber. In such cases, it is preferable to be able to measure and monitor the volumetric flow rate of the superheated steam continuously supplied to the heat treatment chamber. However, in the steam reflow oven apparatus 1 disclosed in Patent Document 1, only the temperature of the superheated steam supplied to the heating furnace 2 can be monitored, but the volumetric flow rate of the superheated steam cannot be measured and monitored.

[0004] As a method for measuring water vapor content, the method disclosed in Patent Document 2 is known. In the method disclosed in Patent Document 2, a gas with a known water vapor content is mixed with the gas to be measured at high temperature, such that the water vapor content of the mixed gas is sufficiently less than that of the gas to be measured. The temperature of the mixed gas is then lowered to a temperature at which humidity can be measured using a hygrometer such as a wet-bulb hygrometer or a resistance hygrometer. The water vapor content of the mixed gas is then determined based on the hygrometer measurement results. Next, the mixing ratio of the gas to be measured and the gas with a known water vapor content is determined, and the water vapor content of the gas to be measured is determined based on this determined mixing ratio and the measured water vapor content of the mixed gas.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-2325

[0008] Patent Document 2: Japanese Patent Application Publication No. 53-93089 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In the steam reflow oven apparatus 1 disclosed in Patent Document 1, only the temperature of the superheated steam supplied to the heating furnace 2, which serves as the destination for the superheated steam, can be monitored; the volumetric flow rate of the superheated steam cannot be measured and monitored. Furthermore, in the measurement method disclosed in Patent Document 2, the gas to be measured is mixed with a gas of known steam content to lower the temperature, and then the steam content of the mixed gas is determined using a hygrometer. Based on this steam content and the mixing ratio of the mixed gas, the steam content of the gas to be measured is measured. Therefore, it is impossible to measure and monitor the volumetric flow rate of the superheated steam continuously supplied to the destination for the superheated steam.

[0011] In order to measure and monitor the volumetric flow rate of superheated steam continuously supplied to its destination, it is desirable to realize a flow meter capable of measuring the volumetric flow rate of superheated steam. The inventors of this application have repeatedly and thoroughly studied methods for realizing such a flow meter, and as a result, have realized that by using an area flow meter, the volumetric flow rate of superheated steam can be measured and monitored. On the other hand, in order to design an area flow meter, it is necessary to know the density of the fluid to be measured. However, in order to know the density of superheated steam at a specified temperature and pressure, a dedicated device is required to generate superheated steam at that specified temperature and pressure and to measure its density, making it difficult to easily obtain this density.

[0012] The object of the present invention is to provide: a method for estimating the density of superheated steam, which can easily determine the density of superheated steam at a specified temperature and a specified pressure; and a method for measuring the volumetric flow rate of superheated steam using an area flow meter designed using the density estimated by the estimation method.

[0013] Methods for solving problems

[0014] (1) In order to solve the above problems, the method for estimating the density of superheated steam of the present invention includes the following steps: a hypothetical density calculation step, based on the temperature T under standard conditions. ntp (K) and pressure P ntp Given the conditions of (Pa) and the molecular weight of water M (g / mol), the hypothetical density ρ is calculated using the ideal gas law. ntp (kg / m 3 The hypothetical density ρ mentioned above ntp (kg / m 3The following steps are used to estimate the density of superheated steam under the aforementioned standard conditions, assuming it is an ideal gas and existing in the aforementioned standard state; and to estimate the density using the hypothetical density ρ calculated in the hypothetical density calculation step. ntp The specified temperature T was calculated based on Boyle-Charlie's law. pd (K) and the specified pressure P pd The density ρ of the superheated steam in the above state (Pa) est (kg / m 3 Therefore, the temperature T specified above can be deduced. pd And the pressure P specified above pd The density ρ of the superheated steam in the above state est .

[0015] (2) In the above-mentioned imaginary density calculation step, the imaginary density ρ is calculated by the following equation (1). ntp .

[0016]

[0017] Here, R is the gas constant (J / (K·mol)).

[0018] (3) In the above density estimation step, the specified temperature T is calculated by the following formula (2). pd And the pressure P specified above pd The density ρ of the superheated steam in the above state est .

[0019]

[0020] (4) In order to solve the above problems, in the method for measuring the volumetric flow rate of superheated steam of the present invention, the pressure P is adjusted to the pressure specified above. pd and the temperature T specified above pd The superheated steam is supplied to the point where the density ρ is estimated according to the estimation method for the density of the superheated steam described above. est An area flow meter designed for measuring fluid flow is used to measure the volumetric flow rate of superheated steam passing through the area flow meter.

[0021] Invention Effects

[0022] According to the present invention, a method for estimating the density of superheated steam can be provided, which can easily determine the density of superheated steam at a specified temperature and specified pressure; further, a method for measuring the volumetric flow rate of superheated steam using an area flow meter designed using the density estimated by the estimation method can be provided. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating a method for estimating the density of superheated steam in an embodiment of the present invention.

[0024] Figure 2 This is a flowchart illustrating a method for measuring the volumetric flow rate of superheated steam according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of an area flow meter used to measure the volumetric flow rate of superheated steam.

[0026] Figure 4 (A) is a schematic cross-sectional view showing the internal structure of an area flow meter. Figure 4 (B) is Figure 4 A sectional view of (A) at the XX line in the view position.

[0027] Figure 5 This is a diagram showing the system configuration for measuring the volumetric flow rate of superheated steam.

[0028] Figure 6 This is a graph showing the measurement results of the volumetric flow rate of superheated steam. Detailed Implementation

[0029] Embodiments of the present invention will now be described with reference to the accompanying drawings. The present invention, as a method for estimating the density of superheated steam and a method for measuring the volumetric flow rate of superheated steam, can be widely applied to various uses. In the following description, the method for estimating the density of superheated steam according to this embodiment will first be described, followed by the method for measuring the volumetric flow rate of superheated steam according to this embodiment, and further, a system for measuring the volumetric flow rate of superheated steam using the method for measuring the volumetric flow rate of superheated steam according to this embodiment will be described.

[0030] [Method for estimating the density of superheated steam]

[0031] Superheated steam is water vapor heated to a temperature higher than its boiling point; it is dry water vapor with a temperature above its boiling point. Since superheated steam is dry water vapor with a temperature higher than its boiling point, it does not exist under standard conditions (0°C, 1 atmosphere). However, in the method for estimating the density of superheated steam in this embodiment, the hypothetical density ρ of superheated steam is first determined, assuming that the superheated steam is an ideal gas and exists under standard conditions. ntp Furthermore, in the method for estimating the density of superheated steam in this embodiment, the calculated hypothetical density ρ is used. ntpBased on Boyle-Charlie's law, for superheated steam at a specified temperature T, the density of the object to be determined is... pd And the specified pressure P pd The density ρ of superheated steam in the state is estimated. est .

[0032] Figure 1 This is a flowchart illustrating a method for estimating the density of superheated steam according to embodiments of the present invention. (Refer to...) Figure 1 The method for estimating the density of superheated steam in this embodiment is configured to include a hypothetical density calculation step S11 and a density estimation step S12.

[0033] In the hypothetical density calculation step S11, the superheated steam is first assumed to be an ideal gas and is assumed to be under standard conditions (i.e., temperature 0℃ (273.15K) and pressure 1 atmosphere (1.01325×10⁻⁶). 5 Hypothetical superheated steam existing in the state of Pa). Then, based on the temperature T under standard conditions. ntp (K) and pressure P ntp Given the conditions of (Pa) and the molecular weight of water M (g / mol), the hypothetical density ρ is calculated using the ideal gas law. ntp (kg / m 3 The hypothetical density is the density of the hypothetical superheated steam under standard conditions, assuming it exists in standard conditions.

[0034] If we consider 1 mol of hypothetical superheated steam in standard state, then using the gas constant R (J / (K·mol), according to the ideal gas law, we can derive the following equation (a) for 1 mol of hypothetical superheated steam in standard state.

[0035]

[0036] Here, the pressure P under the above standard conditions... ntp For example, P ntp =1.01325×10 5 (Pa). Furthermore, the molecular weight M of water is set in the form of molar mass, for example, M = 18 (g / mol). Furthermore, the gas constant R is, for example, R = 8.31 (J / (K·mol)). Furthermore, the temperature T under the above standard conditions... ntp For example, T ntp =273.15(K).

[0037] Based on equation (a) above, the hypothetical density ρ of superheated steam existing under standard conditions is assumed. ntp (kg / m 3 It is calculated by the following formula (b).

[0038]

[0039] Pressure P under standard conditions ntp For example, using P ntp =1.01325×10 5 (Pa), the molecular weight of water M, for example, M = 18 (g / mol), the gas constant R, for example, R = 8.31 (J / (K·mol)), and the temperature under standard conditions T. ntp Use T ntp At K = 273.15, assume the hypothetical density ρ of the hypothetical superheated steam existing in standard conditions. ntp For example, it is calculated as

[0040] In the density estimation step S12, the hypothetical density ρ calculated in the hypothetical density calculation step S11 is used. ntp The specified temperature T was calculated based on Boyle-Charlie's law. pd (K) and the specified pressure P pd The density ρ of superheated steam in the state of (Pa) est (kg / m 3 From this, the specified temperature T is deduced. pd And the specified pressure P pd The density ρ of superheated steam in a certain state est It should be noted that the specified temperature T pd and the specified pressure P pd It is the estimated density ρ of superheated steam. est The desired temperature T of superheated steam under the desired conditions pd and pressure P pd .

[0041] When 1 mol of hypothetical superheated steam under standard conditions and 1 mol of a specified temperature T are set... pd And the specified pressure P pd When the superheated steam is in a certain state, based on Boyle-Charlie's law, the following equation (c) is derived.

[0042]

[0043] According to equation (c) above, the specified temperature T pd And the specified pressure P pd The density ρ of superheated steam in a certain state est It is calculated by the following formula (d).

[0044]

[0045] The density of hypothetical superheated steam, assumed to exist under standard conditions, i.e., the hypothetical density ρ. ntp For example, using ρ calculated in the example above ntp =0.8035 (kg / m 3 ), as the pressure P under standard conditions ntp For example, using P ntp =1.01325×10 5 (Pa), temperature T under standard conditions ntp For example, using T ntp =273.15 (K) (i.e., 0℃), as the specified pressure P pd For example, using P pd =1.01325×10 5 (Pa), as the specified temperature T pd For example, using T pd =453.15(K) (i.e. 180℃), the specified temperature T pd And the specified pressure P pd The density ρ of superheated steam in a certain state est For example, it is calculated as

[0046] As described above, according to the method for estimating the density of superheated steam in this embodiment, the density of the hypothetical superheated steam, i.e., the hypothetical density ρ, is calculated from the ideal gas law assuming that the superheated steam exists in the standard state. ntp Further using the hypothetical density ρ ntp Based on Boyle-Charlie's law, the specified temperature T is calculated and estimated. pd And the specified pressure P pd The density ρ of superheated steam in a certain state est This allows for easy control of the density ρ. est Therefore, it is not necessary to construct a system to generate the specified temperature T. pd And the specified pressure P pd In the case of a specialized device for measuring the density of superheated steam in its current state, the specified temperature T of the object can also be easily determined. pd And the specified pressure P pd The density ρ of superheated steam in a certain state est .

[0047] [Method for determining the volumetric flow rate of superheated steam]

[0048] Next, the method for measuring the volumetric flow rate of superheated steam according to an embodiment of the present invention will be described. In the method for measuring the volumetric flow rate of superheated steam in this embodiment, firstly, an area flow meter fm is fabricated and prepared. This area flow meter fm is based on a density ρ estimated using the density estimation method for superheated steam described above. est The method for measuring the fluid is designed. Then, it is adjusted to the specified pressure P. pd and the specified temperature T pd Superheated steam is supplied to the point where the density ρ is... est An area flow meter fm is designed to measure the volumetric flow rate Q of superheated steam passing through the area flow meter fm.

[0049] Figure 2 This is a flowchart illustrating the method for measuring the volumetric flow rate of superheated steam according to this embodiment. When implementing the method for measuring the volumetric flow rate of superheated steam according to this embodiment, a pressure P is first generated and adjusted to a predetermined value. pd and the specified temperature T pd Superheated steam (step S21). Specified pressure P pd and the specified temperature T pd The superheated steam is generated by a superheated steam generator, which is equipped with a boiler and a superheater. Using the superheated steam generator, water is heated in the boiler and evaporated to generate saturated steam at its boiling point. The saturated steam generated in the boiler is further heated in the superheater and heated at a specified pressure P. pd Heating to the specified temperature T pd Generates the specified pressure P pd And the specified temperature T pd Superheated steam in a certain state.

[0050] When the specified pressure P is generated pd And the specified temperature T pd When superheated steam is in a certain state, the superheated steam is supplied to the area flow meter fm (step S22). The area flow meter fm is used as a... Figure 1 The density ρ is estimated by the method shown in the flowchart. est The design utilizes a method for measuring superheated steam in fluids. Superheated steam is a gas, and by determining the pressure and temperature, the density of the superheated steam becomes a specific value corresponding to those pressures and temperatures. The specified pressure P... pd And the specified temperature T pd The density of superheated steam in the state becomes... Figure 1 The density ρ estimated by the method shown est That is, the area flow meter fm operates according to the specified pressure P.pd And the specified temperature T pd The density ρ of the state est The design utilizes a method for measuring the volumetric flow rate of superheated steam.

[0051] The specified pressure P pd and the specified temperature T pd And density ρ est Superheated steam in a certain state is supplied according to the density ρ est The area flow meter fm is designed to measure the volumetric flow rate of superheated steam, and the steam is passed through the area flow meter fm at a specified pressure P. pd and the specified temperature T pd And density ρ est Superheated steam in a certain state passes through an area flow meter fm, thereby measuring the volumetric flow rate Q of the superheated steam (step S23). The superheated steam with the measured volumetric flow rate Q flows out of the area flow meter fm and is supplied to the destination of the superheated steam supply (step S24).

[0052] Here, we further explain the relationship between density ρ and density ρ. est The area flow meter fm measures the volumetric flow rate of superheated steam in a given state. Figure 3 This is a schematic diagram of an area flow meter fm used to measure the volumetric flow rate of superheated steam. Figure 4 (A) is a schematic cross-sectional view showing the internal structure of the area flow meter fm. Figure 4 (B) is Figure 4 A cross-sectional view of (A) at the viewpoint along line XX. (Refer to...) Figure 3 and Figure 4 The area flow meter fm is connected to the upstream side piping 11, and is supplied with water at a temperature T adjusted to the specified temperature by the upstream side piping 11. pd and the specified pressure P pd Superheated steam. The specified temperature T supplied by upstream piping 11. pd and the specified pressure P pd Superheated steam in a certain state passes through an area flow meter fm, which measures the volumetric flow rate Q of the superheated steam. A downstream piping 12 is connected to the area flow meter fm. The superheated steam, whose volumetric flow rate Q has been measured by the area flow meter fm, flows out from the area flow meter fm to the downstream piping 12, and is then supplied to the destination of the superheated steam supply through the downstream piping 12.

[0053] The area flow meter fm includes a flow meter body 13, a conical tube 14, a float 15, etc. The flow meter body 13 is connected to an upstream side pipe 11 and a downstream side pipe 12, and is housed in a casing that accommodates the conical tube 14. It should be noted that the upstream side pipe 11 and the downstream side pipe 12 connected to the flow meter body 13 are connected to the conical tube 14 inside the flow meter body 13. A scale 13a is provided on the front of the flow meter body 13 for reading the volumetric flow rate Q of superheated steam measured by the area flow meter fm.

[0054] The tapered tube 14 of the area flow meter fm is arranged inside the flow meter body 13, extending vertically, and is designed so that superheated steam supplied by the upstream piping 11 flows from bottom to top through the tube. The tapered tube 14 is cone-shaped with a cross-sectional area that gradually increases from the lower end to the upper end. The lower end of the tapered tube 14 is connected to the upstream piping 11, and the upstream piping 11 communicates with the interior of the tapered tube 14. The upper end of the tapered tube 14 is connected to the downstream piping 12, and the interior of the tapered tube 14 communicates with the downstream piping 12. The superheated steam supplied from the upstream piping 11 to the lower end of the tapered tube 14 flows from bottom to top through the tapered tube 14, and from the upper end of the tapered tube 14 to the downstream piping 12. It should be noted that... Figure 4 In (A), the direction of flow of superheated steam is indicated by a dashed arrow.

[0055] The float 15 of the area flow meter fm is disposed inside the conical tube 14. The float 15 is, for example, a sphere made of metal, ceramic or resin. The float 15 is configured to move up and down in response to the volumetric flow rate Q of the superheated steam flowing inside the conical tube 14.

[0056] Adjusted to the specified temperature T pd and the specified pressure P pd Superheated steam is introduced from the upstream side pipe 11 to the lower end of the conical pipe 14, flowing upwards through the conical pipe 14. As the superheated steam flows upwards in the conical pipe 14, the float 15, due to the pressure difference between its lower and upper sides and the relationship between its weight and buoyancy, is positioned in equilibrium relative to the conical pipe 14, based on the volumetric flow rate Q of the upward-flowing superheated steam. Then, based on the equilibrium position of the float 15 relative to the conical pipe 14, the volumetric flow rate Q of the superheated steam flowing upwards through the conical pipe 14 is measured. The volumetric flow rate Q of the superheated steam is measured by reading the scale 13a at the equilibrium position of the float 15.

[0057] It should be noted that the superheated steam supplied to the area flow meter fm is adjusted to a specified temperature T. pd and the specified pressure P pdAdjust to the specified temperature T pd and the specified pressure P pd The density of superheated steam is determined by utilizing... Figure 1 The density ρ is estimated by the method shown in the flowchart. est The area flow meter fm is adjusted to the specified temperature T. pd And the specified pressure P pd And become density ρ est The method is set by measuring the volumetric flow rate Q of the superheated steam.

[0058] It should be noted that in the area flow meter fm, based on the force balance relationship of the float 15 inside the tapered tube 14, the measured volumetric flow rate Q of the superheated steam is expressed by the following equation (e).

[0059]

[0060] In equation (e) above, "C" is the discharge coefficient, which is the adjustment coefficient between the flow rate obtained from actual experiments under the conditions of the area flowmeter fm and the theoretical formula. "A" represents the flow area, which is the area of ​​superheated steam flowing between the inner circumference of the conical tube 14 and the outer circumference of the float 15 at the equilibrium position of the float 15. That is, "A" is the area of ​​the difference between the cross-sectional area of ​​the inner circumference of the conical tube 14 and the cross-sectional area of ​​the maximum diameter of the float 15 at the equilibrium position of the float 15. Figure 4 The area represented by the symbol A in (B). "g" is the acceleration due to gravity. "V" f "That is the volume of float 15." A f "This is the cross-sectional area of ​​the maximum diameter of float 15, which is..." Figure 4 (B) consists of a double-headed arrow and the symbol A. f The area of ​​the region represented. "ρ" f "That's the density of float 15." ρ est "The density used in the design of the area flow meter fm is the density of the superheated steam that the area flow meter fm measures, and it is the density of the superheated steam at the specified temperature T." pd and the specified pressure P pd The density of superheated steam in a certain state.

[0061] In equation (e) above, the flux coefficient C, the gravitational acceleration g, and the volume V of float 15 are... f The cross-sectional area A of the maximum diameter of float 15 f And the density ρ of float 15 f It is a definite value because the superheated steam is adjusted to a specified pressure P. pd and the specified temperature T pd Therefore, the density ρ of the superheated steam of the object being measured is... estIt is also a definite value. Therefore, in the area flow meter fm, the flow area A, determined by the position of the float 15 inside the tapered tube 14, is related to the volumetric flow rate Q of the superheated steam passing through it. The volumetric flow rate Q of the superheated steam is determined by detecting its position.

[0062] It should be noted that in the area flow meter fm, for example, regarding the flow rate display value corresponding to the scale 13a used to read the measured volumetric flow rate Q of the superheated steam, it is assumed that the superheated steam is in a standard state, and the flow rate Q is displayed in the form of volumetric flow rate converted to the standard state. Alternatively, the measurement of the volumetric flow rate Q of the superheated steam in the area flow meter fm can also be performed without using the scale 13a. For example, a magnet can be provided on the float 15, and the position of the float 15 relative to the conical tube 14 can be magnetically detected by detecting the magnitude of the magnetic force from the magnet, thereby measuring the volumetric flow rate Q of the superheated steam. In this case, the area flow meter fm is configured to display the measured value of the volumetric flow rate Q determined by magnetically detecting the position of the float 15 relative to the conical tube 14.

[0063] [Volume Flow Measurement System]

[0064] Next, the system for measuring the volumetric flow rate Q of superheated steam using the method for measuring the volumetric flow rate of superheated steam in this embodiment will be described.

[0065] Figure 4 This diagram illustrates the structure of a volumetric flow rate measuring system 20 for measuring the volumetric flow rate Q of superheated steam using the method described in this embodiment. The volumetric flow rate measuring system 20 includes a superheated steam generator 21, an upstream piping 11, an area flow meter fm, a downstream piping 12, and a controller 22. The volumetric flow rate measuring system 20 generates a specified temperature T in the superheated steam generator 21. pd and the specified pressure P pd The generated superheated steam is supplied to an area flow meter fm, where the volumetric flow rate Q is measured. The superheated steam with measured volumetric flow rate Q is then supplied to a heat treatment apparatus 30, which is the destination of the superheated steam supply. It should be noted that the heat treatment apparatus 30 is configured, for example, to heat-treat a ceramic or metal workpiece using superheated steam. In the heat treatment apparatus 30, the workpiece is heat-treated by continuously supplying superheated steam supplied via the volumetric flow rate measurement system 20.

[0066] In the superheated steam generator 21, a specified temperature T is generated. pd and the specified pressure Ppd The superheated steam is generated in a specific state. The superheated steam generator 21 is configured to include a boiler and a superheater, the operation of which is controlled by a controller 22. The controller 22 generates superheated steam at a predetermined temperature T. pd and the specified pressure P pd The superheated steam generator 21 is controlled by the state of superheated steam.

[0067] Upstream piping 11 connects the superheated steam generator 21 to the area flow meter fm, transmitting the steam generated by the superheated steam generator 21 at a specified temperature T. pd and the specified pressure P pd Superheated steam in a specific state is supplied to the area flow meter fm. Additionally, a temperature sensor 23 and a pressure sensor 24 are installed on the upstream piping 11. These sensors are located near the section of the upstream piping 11 that connects to the area flow meter fm, and respectively detect the temperature and pressure of the superheated steam supplied from the upstream piping 11 to the area flow meter fm. The temperature sensor 23 and pressure sensor 24 are electrically connected to the controller 22, and the temperature detected by the temperature sensor 23 and the pressure detected by the pressure sensor 24 are sent to the controller 22. The controller 22 controls the boiler and superheater of the superheated steam generator 21 based on the detection values ​​of the temperature sensor 23 and pressure sensor 24, to ensure that the superheated steam generated by the superheated steam generator 21 reaches a predetermined temperature T. pd and the specified pressure P pd The system is controlled in a specific manner. Additionally, a heater 25 is installed on the upstream piping 11. The heater 25 is installed to prevent the temperature of the superheated steam passing through the upstream piping 11 from decreasing by heating the upstream piping 11 from its surroundings. The heater 25 is electrically connected to the controller 22, and its operation is controlled by the controller 22.

[0068] The area flow meter fm is supplied from the upstream side piping 11 and adjusted to the specified temperature T. pd and the specified pressure P pd The superheated steam is used to measure the volumetric flow rate Q of the superheated steam passing through the conical tube 14 of the area flow meter fm. The superheated steam with the measured volumetric flow rate Q is then supplied to the downstream piping 12. The area flow meter fm is used according to the... Figure 1 The density ρ is estimated by the method shown in the flowchart. est The design incorporates a method for measuring superheated steam. The superheated steam supplied to the area flow meter fm is adjusted to a specified temperature T. pd And the specified pressure P pd The state is density ρ est Superheated steam in a certain state. To bring the specified temperature T...pd And the specified pressure P pd The density ρ of the state est The superheated steam passes through an area flow meter fm, thereby measuring the volumetric flow rate Q of the superheated steam.

[0069] Downstream piping 12 connects an area flow meter fm to the heat treatment unit 30, supplying superheated steam, the volumetric flow rate Q of which is measured using the area flow meter fm, to the heat treatment unit 30. Additionally, a flow regulating valve 26 is installed on downstream piping 12. The flow regulating valve 26 is electrically connected to a controller 22, and its opening is adjusted based on commands from the controller 22. Adjusting the opening of the flow regulating valve 26 controls the flow rate of superheated steam supplied from downstream piping 12 to the heat treatment unit 30. Furthermore, a heater 27 is installed on downstream piping 12. The heater 27 is installed to prevent the temperature of the superheated steam supplied to the heat treatment unit 30 through downstream piping 12 from decreasing by heating the downstream piping 12 from its surroundings. The heater 27 is electrically connected to the controller 22, and its operation is controlled by the controller 22.

[0070] The operation is carried out by the aforementioned volumetric flow rate measurement system 20. Figure 2 The flowchart illustrates the method for measuring the volumetric flow rate of superheated steam in this embodiment. The superheated steam generator 21 operates based on the control of the controller 22, thereby generating steam at a predetermined temperature T. pd and the specified pressure P pd Superheated steam (step S21). The generated steam reaches a specified temperature T. pd And the specified pressure P pd Superheated steam in a certain state is supplied to the facility according to the requirements of the upstream side piping 11. Figure 1 The density ρ is estimated by the method shown in the flowchart. est The area flow meter fm is designed using a method that measures superheated steam (step S22). The specified temperature T is then set. pd And the specified pressure P pd The density ρ of the state est The superheated steam passes through the area flow meter fm, and the volumetric flow rate Q of the superheated steam passing through the area flow meter fm is measured (step S23). The superheated steam with the measured volumetric flow rate Q flows out of the area flow meter fm and is supplied to the heat treatment device 30, which is the destination of the superheated steam supply (step S24).

[0071] A volumetric flow rate measurement system 20 was actually constructed, and an experiment was conducted to measure the volumetric flow rate of superheated steam. Figure 6This is a graph showing the measurement results of the volumetric flow rate of superheated steam. Regarding the area flow meter fm, an area flow meter designed according to the method for measuring superheated steam at a specified temperature T is used. pd = 453.15 (K) (i.e., 180℃) and the specified pressure P pd =1.01325×10 5 (Pa) superheated steam and density ρ est =0.4843 (kg / m 3 The superheated steam is then generated in the superheated steam generator 21 to a specified temperature T. pd (453.15(K)) and the specified pressure P pd (1.01325×10 5 (Pa)) superheated steam, change the valve opening of flow regulating valve 26, and use area flow meter fm to measure the volumetric flow rate of superheated steam at various flow rates.

[0072] Furthermore, to estimate the actual volumetric flow rate of superheated steam supplied from the superheated steam generator 21 to the area flow meter fm, the actual amount of water consumed per unit time in the superheated steam generator 21 to generate superheated steam is measured, and a flow conversion value is calculated, converting this measured water amount into the volumetric flow rate of superheated steam. The actual volumetric flow rate of superheated steam supplied from the superheated steam generator 21 to the area flow meter fm is then calculated using this flow conversion value. It should be noted that the measured value of the volumetric flow rate of superheated steam based on the area flow meter fm, and the flow conversion value based on the actual water consumption in the superheated steam generator 21, are assumed to be under standard conditions and are calculated as volumetric flow rates converted to standard conditions. Figure 6 In the diagram, the measured volumetric flow rate of superheated steam based on the area flow meter fm is displayed using a triangle symbol, while the flow rate conversion value based on the actual water consumption in the superheated steam generator 21 is displayed using a quadrilateral symbol.

[0073] like Figure 6 As shown, the volumetric flow rate of superheated steam, measured by the area flow meter fm, is changed by altering the valve opening of the flow regulating valve 26. Furthermore, as... Figure 6 As shown, it can be confirmed that the measured value of the volumetric flow rate of superheated steam measured using the area flow meter fm has a good correlation with the flow rate conversion value based on the actual water consumption in the superheated steam generator 21 (i.e., the value obtained by calculating the actual volumetric flow rate of superheated steam supplied to the area flow meter fm based on the actual water consumption in the superheated steam generator 21). Therefore, by utilizing the density ρ... estThe area flow meter fm is designed to measure the temperature of superheated steam and is adjusted to the specified temperature T. pd and the specified pressure P pd The superheated steam can be used to appropriately measure the volumetric flow rate of the superheated steam.

[0074] [Effects of this implementation method]

[0075] When superheated steam is continuously supplied to a heat treatment unit that serves as the destination of the superheated steam, it is desirable to be able to measure the volumetric flow rate of the continuously supplied superheated steam. As a method for measuring the volumetric flow rate of the superheated steam, an area flow meter is considered. In this case, in order to design the area flow meter, it is necessary to know the density of the superheated steam that is being measured. According to this embodiment, the density ρ of the hypothetical superheated steam, assuming that the superheated steam exists in a standard state, is calculated from the ideal gas law. ntp Further using the hypothetical density ρ ntp Based on Boyle-Charlie's law, the specified temperature T is calculated and estimated. pd And the specified pressure P pd The density ρ of superheated steam in a certain state est It is possible to easily grasp the density ρ est Therefore, it is not necessary to construct a system to generate the specified temperature T. pd And the specified pressure P pd In the case of a specialized device for measuring the density of superheated steam in its current state, the specified temperature T of the object can also be easily determined. pd And the specified pressure P pd The density ρ of superheated steam in a certain state est .

[0076] Furthermore, according to this embodiment, it is possible to adjust to a predetermined temperature T. pd and the specified pressure P pd Superheated steam is supplied to the point where the density ρ is estimated as described above. est An area flow meter fm is designed to measure the volumetric flow rate of the superheated steam passing through it. Furthermore, according to this embodiment, when superheated steam is continuously supplied to the heat treatment apparatus 30, which is the destination of the superheated steam supply, the volumetric flow rate of the continuously supplied superheated steam can be measured and monitored using the area flow meter fm.

[0077] [Variation Example]

[0078] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made to implement it as long as they are described in the claims. For example, the following variations can also be implemented.

[0079] In the above embodiments, the specified temperature T pd exemplify T pd = 453.15 (K), as the specified pressure P pd exemplify P pd =1.01325×10 5 (Pa) illustrates the estimated density ρ of superheated steam. est In this way, but these values ​​are merely illustrative, serving as a given temperature T. pd and the specified pressure P pd Since any temperature and pressure at which superheated steam exists can be selected, any temperature and pressure can be chosen. Therefore, the desired temperature T can be easily estimated and determined. pd and the specified pressure P pd The density ρ of superheated steam in a certain state est .

[0080] The above embodiment illustrates a spherical float 15 for the area flow meter fm, but this is not always the case. The float of the area flow meter fm can have various shapes, such as a combination of conical and cylindrical shapes.

[0081] Industrial applicability

[0082] This invention can be widely used as a method for estimating the density of superheated steam and for determining the volumetric flow rate of superheated steam.

[0083] Symbol Explanation

[0084] FM area flow meter

[0085] 11 Upstream side piping

[0086] 12 Downstream piping

[0087] 13 Flowmeter Body

[0088] 14 tapered tube

[0089] 15 floats

[0090] 20 Volumetric Flow Measurement System

[0091] 21 Superheated Steam Generator

[0092] 22 controllers

[0093] 23 Temperature Sensor

[0094] 24 pressure sensors

[0095] 25, 27 heaters

[0096] 26 Flow regulating valve

[0097] 30 Heat Treatment Unit

Claims

1. A method for estimating the density of superheated steam, characterized in that, It involves the following steps: Hypothetical density calculation steps, based on temperature T under standard conditions. ntp and pressure P ntp Given the conditions and the molecular weight M of water, the hypothetical density ρ is calculated using the ideal gas law. ntp The hypothetical density ρ ntp The density of the hypothetical superheated steam under the standard conditions is given by treating superheated steam as an ideal gas and assuming it exists in the standard state, wherein the temperature T... ntp The unit is K, and the pressure P is... ntp The unit is Pa, the unit of the molecular weight M is g / mol, and the unit of the hypothetical density ρ is... ntp The unit is kg / m 3 ;as well as The density estimation step uses the hypothetical density ρ calculated in the hypothetical density calculation step. ntp The specified temperature T was calculated based on Boyle-Charlie's law. pd And the specified pressure P pd The density ρ of the superheated steam in the state est Therefore, the specified temperature T is deduced. pd And the specified pressure P pd The density ρ of the superheated steam in the state est The temperature T pd The unit is K, and the pressure P is... pd The unit is Pa, and the density ρ est The unit is kg / m 3 .

2. The method for estimating the density of superheated steam as described in claim 1, characterized in that, In the hypothetical density calculation step, the hypothetical density ρ is calculated using the following equation (1). ntp , Here, R is the gas constant, and the unit of the gas constant is J / (K·mol).

3. The method for estimating the density of superheated steam as described in claim 1, characterized in that, In the density estimation step, the specified temperature T is calculated using the following equation (2). pd And the specified pressure P pd The density ρ of the superheated steam in the state est , 4. A method for determining the volumetric flow rate of superheated steam, characterized in that, The pressure P will be adjusted to the specified value. pd and the specified temperature T pd The superheated steam is supplied to a density ρ estimated according to the method for estimating the density of the superheated steam as described in any one of claims 1 to 3. est An area flow meter is designed to measure the volumetric flow rate of superheated steam passing through it.

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