JP6862246B2 - Dryness measuring device - Google Patents

Description

Embodiments of the present invention relates to a dryness of the measurement equipment.

Conventionally, steam is used as heat energy in thermal power plants and factories. It is known that the dryness of steam affects the efficiency of steam energy conversion. The vapor has a state in which a liquid phase and a gas phase are mixed, and the degree of dryness represents the ratio of the liquid phase and the gas phase in the vapor. The degree of dryness is expressed in the range of 0 to 1. When the ratio of the liquid phase is large, the degree of dryness is close to 0, and when the ratio of the liquid phase is small, the degree of dryness is close to 1.

However, regarding the dryness of vapor, since both the liquid phase and the gas phase are water, there is a problem that it is difficult to accurately measure the dryness.

Japanese Unexamined Patent Publication No. 2012-122961

An object of the present invention is to provide the precision better measure the dryness of the steam, to provide a dryness measuring equipment.

In order to solve the above problem, the dryness measuring device of the embodiment is provided on the outside of the measuring tube into which steam flows, and the microwave irradiating unit for irradiating the microwave and the microwave irradiating unit are paired with each other. It is provided on the outside of the measuring tube and is received by the microwave receiving unit that receives the microwave emitted from the microwave irradiation unit, the microwave emitted from the microwave irradiation unit, and the microwave receiving unit. A phase measuring unit that measures the phase difference with a microwave, a temperature input unit that inputs the temperature inside the measuring tube, a pressure input unit that inputs a pressure value in the measuring tube, and a thirst degree in the measuring tube. A table unit that stores the relationship between the phase difference when 0 and the phase difference when the degree of thirst in the measuring tube is 1, by temperature and by pressure, and the phase difference output from the phase measuring unit and the above. It is provided with a dryness calculating means for calculating the dryness of the steam by using the temperature and the pressure value.

The block diagram of the dryness measuring apparatus which is 1st Embodiment. Diagram of the relationship between the specific enthalpy of water and temperature. The figure of the phase difference between the microwave emitted from a microwave irradiation part and the microwave received by a microwave receiving part. Correlation diagram of microwave phase difference with respect to dryness. The block diagram of the dryness measuring apparatus which is 2nd Embodiment. The figure of the phase difference table stored in the storage part. Phase diagram corresponding to the temperature and pressure of water. Correlation diagram of dryness for each temperature corresponding to changes in microwave phase difference. The block diagram of the dryness measuring apparatus which is 3rd Embodiment. The block diagram of the dryness measuring apparatus which is a modification of 3rd Embodiment. The figure of the phase difference between the microwave emitted from the microwave irradiation part and the microwave received by a microwave receiving part at the time of frequency modulation. The figure of the flowchart of the dryness measuring method of a dryness measuring apparatus. The figure of the flowchart of the dryness measuring method of a dryness measuring apparatus.

Hereinafter, embodiments of the dryness measuring device will be described with reference to the drawings.

(First Embodiment)
Hereinafter, the dryness measuring device according to the first embodiment will be described with reference to the drawings.

FIG. 1 is a block diagram of the dryness measuring device 1 according to the first embodiment. The dryness measuring device 1 of the present embodiment is provided on the outside of the measuring tube 10 into which steam flows, and is paired with the microwave irradiation unit 20 for irradiating microwaves and the outside of the measuring tube 10. It has a microwave receiving unit 30 for receiving microwaves irradiated from the microwave irradiating unit 20 and a dryness calculation unit 40.

The dryness calculation unit 40 is a phase measurement unit 41 that measures the phase difference between the microwave emitted from the microwave irradiation unit 20 and the microwave received by the microwave reception unit 30, and the measurement results of the phase measurement unit 41. It has a dryness calculating means 42 for calculating the dryness of steam from the microwave, and a storage unit 43. That is, the dryness measuring device 1 of the present embodiment irradiates the steam with microwaves and measures the dryness of the steam based on the change in the phase of the microwaves.

FIG. 2 is a diagram showing the relationship between the specific enthalpy of water (heat energy per unit mass) and temperature. The horizontal axis is the specific enthalpy and the vertical axis is the temperature.

When the specific enthalpy of water in the liquid phase state increases, the temperature of the water rises and reaches the boiling point. The boiling point is 100 ° C. in an atmospheric pressure (1 atmospheric pressure) environment. Further, when the specific enthalpy of water increases, the liquid phase and the gas phase are mixed. The dryness of steam in this state is as shown in the following equation (1).

Vapor quality = mass of gas phase / (mass of gas phase + mass of liquid phase) ... Equation (1)
When the boiling point is reached, the dryness changes from the liquid phase to the gas phase, so the dryness becomes 0, and when the specific enthalpy increases, the dryness changes from the liquid phase to the gas phase, so the dryness approaches 1. I will go. When the specific enthalpy is further increased, the steam becomes only in the gas phase, and the temperature of the steam becomes higher than the boiling point.

The boiling point changes depending on the pressure of steam. In an environment where the pressure is greater than atmospheric pressure, the boiling point is greater than 100 ° C. The pressure of steam used in thermal power plants and factories is higher than atmospheric pressure. Therefore, the dryness measuring device 1 of the present embodiment is not limited to atmospheric pressure.

FIG. 3 shows the phase difference between the microwave emitted from the microwave irradiation unit 20 and the microwave received by the microwave receiving unit 30 when steam is flowing into the measuring tube 10. The waveform of FIG. 3A is a waveform of a microwave that has passed through the steam in the measuring tube 10 and is received by the microwave receiving unit 30. The waveform of FIG. 3B is a waveform of a microwave emitted from the microwave irradiation unit 20. Let θ be the phase difference between these waveforms. That is, the microwave passes through the steam in the measuring tube, so that a phase difference of θ is generated.

The phase measuring unit 41 of the dryness calculation unit 40 measures the phase difference θ from the waveform of FIG. 3A and the waveform of FIG. 3B.

FIG. 4 is a correlation diagram of the phase difference of microwaves with respect to the dryness of steam. _{Let θ 0 be} the phase difference when the dryness is 0, _{and θ 1 be} the phase difference when the dryness is 1. When the dryness approaches 0, the vapor contains a large amount of liquid phase, so that the propagation speed of microwaves becomes slow and the phase difference θ becomes large. When the dryness approaches 1, the vapor contains a large amount of gas phase, so that the propagation velocity of microwaves becomes faster and the phase difference θ becomes smaller.

The dryness measuring device 1 of the present embodiment _{measures in advance the phase difference θ 0 when the dryness is 0 and the phase difference θ 1} when the dryness is 1, and stores them in the storage unit 43 of the dryness calculation unit 40. There is.

The dryness calculating means 42 of the dryness calculation unit 40 calculates the dryness based on the phase difference θ measured by the phase measuring unit 41 and the correlation diagram of the dryness and the phase difference stored in the storage unit 43. .. As an example, the dryness of the phase difference θ is calculated by linearly interpolating the _{phase difference θ 0} and the phase difference θ _1.

As described above, the dryness measuring device 1 of the present embodiment can accurately measure the dryness of steam by measuring the phase difference θ using microwaves.

(Second Embodiment)
Hereinafter, the dryness measuring device according to the second embodiment will be described with reference to FIG.

As shown in FIG. 5, the dryness measuring device 2 of the present embodiment further provides a temperature measuring unit 50 in the first embodiment, measures the temperature of the steam in the measuring tube 10, and changes the dryness due to the temperature change. It is a measuring device that takes into consideration.

_{The dryness measuring device 3 of the present embodiment obtains the phase differences θ 0} and θ ₁ when the dryness 0 and 1 at a plurality of temperatures are obtained in advance as a sample, and creates a table in the storage unit 43 of the dryness calculation unit 40. ,Remember. FIG. 6 is a diagram of a table of _{phase differences θ 0} and θ ₁ stored in the storage unit 43. In FIG. 6, for example, the temperatures are set to 100, 200, 300. .. .. The temperature is changed to ° C., and the phase differences θ ₀ and θ ₁ at this time are stored, respectively. However, the temperature sample is not limited to the temperature shown in FIG.

Further, the dryness measuring device 3 of the present embodiment has a plurality of tables by changing the pressure. _{In FIG. 6, the phase differences θ 0} and θ ₁ of the respective temperatures when the pressures are 5 MPa, 10 MPa, and 15 MPa are stored, respectively. However, the pressure table sample is not limited to the pressure shown in FIG.

It is assumed that the temperature of the steam in the measuring tube 10 drops from the state of A0 (9 MPa, 380 ° C.) in FIG. 7 to the state of A1 (9 MPa, 340 ° C.). In this case, the vapor quality is 1 because the vapor is only in the gas phase.

It is assumed that the temperature is further lowered to the state of A2 (9 MPa, 300 ° C.). In this case, it is on the curve of the state transition of water in FIG. 7, and the liquid phase and the gas phase are mixed in the vapor. The dryness measuring device 3 of the present embodiment selects a pressure table of 10 MPa closest to 9 MPa from the storage unit 43. After that, the phase difference θ of A2 is _{linearly interpolated using the phase differences θ 0} and θ ₁ of 10 MPa, and the dryness is measured. The method of selecting the values in the table is not limited to one approximate pressure table. For example, in the case of 9 MPa, pressure tables of 5 MPa and 10 MPa may be selected and derived based on _{the phase differences θ 0} and θ _{1 of each pressure table.}

It is assumed that the temperature of the steam further decreases to 260 ° C. If the pressure remains at 9 MPa, it is in the state of A3 (9 MPa, 260 ° C.), only in the liquid phase, and the dryness is 0. However, when the pressure drops, there is a state of A4 (5 MPa, 260 ° C.) in which the liquid phase and the gas phase coexist even at 260 ° C. A4 is on the curve of the state transition of water in FIG.

In the case of A4, the pressure is measured and the state of 5 MPa is input from the outside to the dryness measuring device 3 of the present embodiment. After that, the dryness calculating means 42 of the dryness calculation unit 40 is based on the phase difference θ measured by the phase measuring unit 41 and the phase differences θ ₀ and θ _{1 from the pressure table of 5 MPa stored in the storage unit 43.} The dryness is calculated by linear complementation.

In the above example, the case where the temperature of the steam decreases and the pressure decreases is described, but the same applies when the temperature of the steam increases and the pressure increases.

From FIG. 7, the dielectric constant of water when the dryness is 0 changes greatly with a temperature change. In FIG. 7, the dielectric constant of water at the temperature T2 is ε2.

FIG. 8 is a correlation diagram of the dryness of each of the temperatures T1 and T2 corresponding to the change in the phase difference of the microwave. The phase difference between the temperatures T1 and T2 when the dryness is 0 is α (ε2 / ε1) using the dielectric constants ε1 and ε2. α is a constant.

Assuming that the phase difference of the water to be measured is θ _X1 and the temperature is T1, the dryness is X1. It is assumed that the phase difference changes from the state of _{θ X1 to the state of θ X3.} Assuming that the temperature is constant, the dryness is X2 when the _{phase difference is θ X3 as shown in FIG.}

The dryness measuring device 3 of the present embodiment can measure the fluctuation of the dryness in consideration of the temperature change. It is assumed that the temperature of water changes to T2 ° C. when the phase difference of water changes from the state of _{θ X1 to the state of θ X3.} In this case, _{the dryness when the phase difference changes to θ X3} is X3 from FIG. That is, the dryness measuring device 3 of the present embodiment measures that the dryness changes from X1 to X3 when the phase difference of water changes from the state of _{θ X1 to the state of θ X3 by considering the temperature change.} To do.

When measuring the dryness of steam in a boiler of a thermal power plant, since the permittivity of water hardly changes at 500 ° C. or higher as shown in FIG. 7, the permittivity may be approximated as a constant value. _{In this case, the phase difference θ 0 when the dryness is 0 and the phase difference θ 1} when the dryness is 1 in the vicinity of the critical point (22.1 MPa, 374 ° C.) are measured in advance and stored in the storage unit 43. After that, the phase difference θ is measured for the water in the boiler, and the dryness is calculated from the linear interpolation of _{the phase differences θ 0} and θ _{1 measured in advance.}

As described above, the dryness measuring device 3 of the present embodiment can accurately measure the dryness of steam by measuring the phase difference θ using microwaves in consideration of the temperature change.

(Third Embodiment)
A plurality of dryness measuring devices according to the third embodiment and a dryness measuring method using the third embodiment are provided outside the measuring tube 10 of the dryness measuring device of the first to second embodiments. It is a measuring device provided with a pair of microwave irradiation unit 20 and microwave reception unit 30.

FIG. 9 is a diagram of the dryness measuring device 3 (3A) of the present embodiment. In FIG. 9, two microwave irradiation units 20 (20a, 20b) are arranged in the measuring tube 10 of the dryness measuring device 1 of the first embodiment in the axial direction of the measuring tube (broken line direction in FIG. 9). The two microwave receiving units 30 (30a) and 30 (30b) are arranged in pairs with the microwave irradiation units 20a and 20b, respectively.

The microwave emitted from the microwave irradiation unit 20a propagates in the measuring tube 10 and is received by the microwave reception unit 30a. Further, the microwave irradiated from the microwave irradiation unit 20b propagates in the measuring tube 10 and is received by the microwave receiving unit 30b. That is, the dryness measuring device 3A of FIG. 9 has two pairs of dryness measuring means.

Hereinafter, the dryness measuring device 3A having two pairs of dryness measuring means will be described in detail. However, in the present embodiment, the dryness measuring means is not limited to two pairs. The dryness measuring device 3A may have three or more pairs of dryness measuring means.

The phase measurement unit 41 of the dryness calculation unit 40 has a phase difference θ (θa) between the microwave emitted from the microwave irradiation unit 20a and the microwave received by the microwave reception unit 30a, and the microwave irradiation unit. The phase difference θ (θb) between the microwave emitted from 20b and the microwave received by the microwave receiving unit 30b is measured.

The dryness calculation means 42 of the dryness calculation unit 40 calculates the dryness in the measuring tube 10 based on the phase differences θa and θb measured from the respective dryness measuring means. The method of calculating the dryness based on the phase difference θ is the same as that of the dryness measuring device 1 of the first embodiment.

The dryness calculating means 42 calculates the dryness for each of the phase differences θa and θb, and then averages the dryness. However, the dryness may be calculated by averaging the phase differences θa and θb and using the average phase difference.

(Modified example of the third embodiment)
FIG. 10 is a diagram of the dryness measuring device 3 (3B) of the present embodiment. In FIG. 10, microwave irradiation units 20 (20a, 20c) are arranged in the measurement tube 10 of the dryness measuring device 1 of the first embodiment in the circumferential direction, and the microwave irradiation units 20a and 20c are respectively arranged. Microwave receiving units 30 (30a) and 30 (30c) facing each other in pairs are arranged.

The microwave emitted from the microwave irradiation unit 20a propagates in the measuring tube 10 and is received by the microwave reception unit 30a. Further, the microwave irradiated from the microwave irradiation unit 20c propagates in the measuring tube 10 and is received by the microwave receiving unit 30c. That is, the dryness measuring device 3B of FIG. 10 has two pairs of dryness measuring means. However, in the present embodiment, the dryness measuring means is not limited to two pairs. The dryness measuring device 3B may have three or more pairs of dryness measuring means.

The method for calculating the dryness is the same as that of the dryness measuring device 3A of the third embodiment.

Regarding the dryness measuring device 3 (3A) of the third embodiment and the dryness measuring device 3 (3B) which is a modification thereof, the microwave irradiation unit 20 and the microwave receiving unit of the first dryness measuring device 1 Although a plurality of pairs of 30s have been described, a plurality of pairs of microwave irradiation units 20 and microwaves are provided in a measuring tube 10 provided with a temperature measuring unit 50 as in the dryness measuring device 2 of the second embodiment. The wave receiving unit 30 may be arranged.

Based on the above, the dryness measuring device 3 of the present embodiment accurately measures the dryness of steam by using a plurality of microwave irradiation units 20 and microwave receiving units 30 for measuring the phase difference θ using microwaves. can do.

(Fourth Embodiment)
The dryness measuring device according to the fourth embodiment is a measuring device in which the microwave irradiation unit 20 of the dryness measuring device of the first to third embodiments modulates the frequency to measure the dryness. ..

FIG. 11 shows the phase difference between the microwave emitted from the microwave irradiation unit 20 and the microwave received by the microwave receiving unit 30 when the frequency of the microwave irradiated to the steam is modulated. .. The waveform of FIG. 11A and the waveform of FIG. 11B1 are the same as the waveforms of FIGS. 3A and 3B. At this time, the waveform of the microwave emitted from the microwave irradiation unit 20 is b1, the frequency is f1, and the phase difference is θ _f1 .

The dryness measuring device 4 of the present embodiment modulates the frequency irradiated from the microwave irradiation unit 20 from f1 to f2. Let b2 be the waveform when the frequency is f2. The waveform of the microwave irradiation unit 20 when the frequency is f2 is (b2), and the waveform when propagating through the measuring tube 10 and being received by the microwave receiving unit 30 is (a2). _{Let θ f2} be the phase difference at the frequency f2.

The dryness calculation means 42 of the dryness calculation unit 40 calculates the dryness in the measuring tube 10 based on _{the phase differences θ f1} and θ _{f2 measured from the respective dryness measuring means.} The method of calculating the dryness based on the phase difference θ is the same as that of the dryness measuring device 1 of the first embodiment.

The dryness calculating means 42 calculates the dryness for each of the phase differences θ _f1 and θ _f2 , and then averages the dryness. However, the degree of dryness may be calculated by averaging the _{phase differences θ f1} and θ _{f2 and using the average phase difference.}

When a plurality of pairs of dryness measuring means are provided as in the dryness measuring devices 3A and 3B of the third embodiment, frequency modulation may be performed for each pair.

As described above, the dryness measuring device 4 of the present embodiment can measure a plurality of phase differences by frequency modulation in the measurement of the phase difference θ using microwaves, and can accurately measure the dryness of steam.

(Dryness measurement method)
FIG. 12 is a flowchart of a method for measuring the dryness of the dryness measuring device according to the above-described embodiment. The following dryness measuring method will be described in detail using the dryness measuring device 2 which is the second embodiment, but the same dryness measuring method is used for other dryness measuring devices.

When there is steam for measuring the dryness inside the measuring tube 10, the microwave irradiating unit 20 irradiates the microwave receiving unit 30 with microwaves (step S100). The microwave receiving unit 30 receives the microwave (step S101) and transmits the waveform information to the dryness calculation unit 40. As shown in FIG. 3, the phase measuring unit 41 in the dryness calculation unit 40 has a microwave waveform (b) emitted from the microwave irradiation unit 20 and a microwave waveform (a) received by the microwave receiving unit 30. ) And the phase difference θ is measured (step S102).

Next, the temperature inside the measuring tube 10 is measured by the temperature measuring unit 50 (step S103) and transmitted to the dryness calculation unit 40. After that, the dryness calculation means 42 in the dryness calculation unit 40 reads out the dryness when the _{phase difference θ 0} and θ ₁ corresponding to the measured temperature stored in advance from the storage unit 43, and uses these dryness as the dryness. The dryness of the steam is calculated based on this (step S104).

In the dryness measuring method, the temperature is measured as shown in FIG. 13 (step S103), and then the microwave irradiation unit 20 irradiates the microwave receiving unit 30 with microwaves (step S100), and the microwave receiving unit 30 Receives microwaves (step S101) and measures the phase difference θ (step S102).

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalent scope thereof.

10 ... Measuring tube,
20 ... Microwave irradiation unit,
30 ... Microwave receiver,
40 ... Dryness calculation unit,
41 ... Phase measurement unit,
42 ... Dryness calculation means,
43 ‥‥‥ Memory part,
50 ... Temperature measuring unit.

Claims (7)

A microwave irradiation unit that is provided on the outside of the measuring tube into which steam flows and irradiates microwaves,
A microwave receiving unit that is provided on the outside of the measuring tube in pairs with the microwave irradiation unit and receives microwaves irradiated from the microwave irradiation unit.
A phase measuring unit that measures the phase difference between the microwave emitted from the microwave irradiation unit and the microwave received by the microwave receiving unit, and a phase measuring unit.
A temperature input unit into which the temperature inside the measuring tube is input, and
A pressure input unit into which the pressure value in the measuring tube is input, and
A table unit that stores the relationship between the phase difference when the thirst degree in the measuring tube is 0 and the phase difference when the thirst degree in the measuring tube is 1 by temperature and pressure.
A dryness calculating means for calculating the dryness of the steam using the phase difference, the temperature, and the pressure value output from the phase measuring unit.
A dryness measuring device equipped with. A temperature measuring unit for measuring the temperature of the steam in the measuring tube is further provided.
The measurement result of the temperature measuring unit is input to the temperature input unit .
The dryness measuring device according to claim 1. The dryness measuring device according to claim 1 or 2, wherein the microwave irradiation unit and the microwave receiving unit are provided in a plurality of pairs on the outside of the measuring tube. The phase measuring unit measures a plurality of phase differences for each of the microwave irradiating unit and the microwave receiving unit forming a plurality of pairs.
The dryness measuring device according to claim 3, wherein the dryness calculating means calculates the dryness of the steam based on the average value of the plurality of phase differences. The dryness measuring device according to claim 3 or 4, wherein the plurality of pairs of the microwave irradiation unit and the microwave receiving unit are provided side by side in the axial direction of the measuring tube. The dryness measuring device according to claim 3 or 4, wherein the plurality of pairs of the microwave irradiation unit and the microwave receiving unit are provided side by side in the circumferential direction of the measuring tube. The dryness measuring device according to any one of claims 1 to 6, wherein the microwave irradiation unit modulates the frequency of the microwave to be irradiated into a continuous wave.

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