JP2733717B2 - Two-phase flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-phase flow meter for measuring a two-phase fluid in which water and steam are mixed.

[0002]

2. Description of the Related Art In general, water is represented by the sum of a mist-like flow that flows in dry saturated steam and a pipe wall flow that adheres to the inner wall of a pipe and flows along the inner wall, and steam refers to dry saturated steam. ing. Conventionally, when measuring such a mixed two-phase flow of steam and water, this mixed two-phase flow is first separated into dry saturated steam and saturated water using a steam separator, and the former is replaced with an orifice flow meter. And the latter is measured by an open channel flow meter.

[0003]

In this conventional method,
Two types of flowmeters, a steam separator and an open channel flowmeter, are necessary and expensive, and there are drawbacks such as an increase in the size of the device, and the two-phase fluid is separated into steam and water. Therefore, the fluid is introduced into the branch pipe, sampling is performed, and the flow rate is measured. Thus, there is a disadvantage that continuous measurement cannot be performed in the main pipe.

[0004]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a conical Venturi tube which is provided with an inlet conical portion following an inlet cylindrical portion and which is provided with an inlet conical portion. A diaphragm cylinder is provided, a high-pressure diaphragm mounting hole is provided vertically above the center of the inlet cylinder, and a low-pressure diaphragm mounting hole is provided vertically above the center of the diaphragm cylinder, and the high-pressure diaphragm is mounted in the mounting hole. A diaphragm seal differential pressure gauge that measures the differential pressure of a two-phase fluid from the difference between the output of the side diaphragm and the output of the low-pressure side diaphragm, and the diaphragm mounting hole has the same cross-section as the center of the mounting hole of the diaphragm seal differential pressure gauge of the inlet cylindrical portion. About 90 from the vertical
ダ イ ア A diaphragm seal pressure gauge that is provided in the rotated horizontal direction and detects the pressure of the two-phase fluid based on the output of the diaphragm attached to the attachment hole. The ultrasonic wave is disposed so as to be approximately 60 ° with respect to the flow direction of the phase fluid, and detects the flow rate of the two-phase fluid based on the output of each probe attached to the mounting hole when the ultrasonic wave passes through the center of the cross section. The difference measured by the sound wave anemometer and the diaphragm seal differential pressure gauge
Pressure, the pressure detected by the diaphragm seal pressure gauge
Input the flow rate detected by the
Of the fluids, the mass flow of steam only, the mass flow of water only and
An arithmetic unit that simultaneously and continuously calculates the sum of these mass flow rates
And the mass flow rate of only steam, the mass flow rate of only water, and the sum mass flow rate of the two in the two-phase fluid can be simultaneously and continuously measured. The conical venturi tube has an outlet conical tube following the constricted cylinder, and the length of the inlet cylinder is determined by the inner diameter of the inlet cylinder and the hole diameter for mounting the high-pressure side diaphragm of the diaphragm seal differential pressure gauge. The length of the constricted cylinder is equal to the sum of the inner diameter of the constricted cylinder and the diameter of the hole for attaching the low-pressure side diaphragm of the diaphragm seal differential pressure gauge, and the inner diameter of the outlet of the outlet conical tube is the diameter of the inlet cylinder. It is made to be equal to. In addition, the mounting holes of the diaphragm seal differential pressure gauge and the diaphragm seal pressure gauge are equal to the diameter of the diaphragm, and the angle of the mounting hole is set to an acute angle, and when the stop valve disposed between the diaphragm and the mounting hole is closed. And a safety valve for raising the negative pressure of the diaphragm to the atmospheric pressure. Further, the tip position of the probe of the ultrasonic anemometer is arranged at a distance of 10 to 20 mm from the inner wall surface of the tube of the inlet cylindrical portion, and the angle of the mounting hole of the probe is made acute, and the stop valve of the socket for mounting the probe is provided. Is provided with a safety valve for preventing the probe from being damaged when is closed. The arithmetic unit calculates the sum of the mass flow rate of the steam-only mass flow rate and the water-only mass flow rate by multiplying a value obtained by dividing the differential pressure by the flow velocity by a correction term,
The mass flow rate of only steam and the mass flow rate of only water are calculated from the calculated values.

[0005]

Therefore, according to the present invention, the mass flow rate of only steam, the mass flow rate of only water, and the mass flow rate of the sum thereof can be simultaneously and continuously measured in the two-phase fluid. Can be continuously measured as it is, and a conventionally used steam-water separator is not required, so that the configuration can be made inexpensively, and wasteful consumption of fluid is prevented as compared with the conventional sampling method.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
You. FIG. 1 is a view showing one embodiment of the present invention.
FIG. 2 is a front view showing the configuration of a conical venturi tube to be produced.
You. FIG. 2 is a side view thereof.

It is important to use conical Venturi tubes for measuring two-phase fluids. By using this, it is removed that water contained in the two-phase fluid accumulates on the upstream side of the throttle cylindrical portion 6. 1, the arrows in FIG. 2 shows a two-phase flow direction of the fluid 1 flowing into the circular pyramidal venturi. The two-phase flow meter is mounted by fixing the upstream flange 2 and the downstream flange 3 to the horizontal pipe flange 68, respectively. Two-phase fluid, the inlet cylindrical portion 4 and the conical angle theta ₂ is 21 ° entrance cone pipe 5, the cylindrical portion 6 stop, cone angle theta ₃ is through outlet 15 ° outlet conical tube 7. Comparing the cross-sectional areas of the inlet cylindrical portion 4 and the throttle cylindrical portion 6, the throttle cylindrical portion 6 is small. Therefore, a flow velocity difference occurs between the two cylindrical portions.

In the inlet cylindrical portion 4 and the throttle cylindrical portion 6, differential pressure outlets 8, 9 are respectively arranged vertically vertically at the center in the longitudinal direction. The hole diameter of the differential pressure outlets 8 and 9 is equal to the diameter of the diaphragm. The length of the inlet cylindrical portion 4 is a value obtained by adding the hole diameter of the differential pressure outlet 8 to the inner diameter. Similarly, the length of the constricted cylindrical portion 6 is set to the differential pressure outlet 9 on the inner diameter of the constricted cylindrical portion.
Is the value obtained by adding the hole diameter of The two diaphragms 1 of the diaphragm seal differential pressure gauge 26 are connected to the differential pressure outlets 8 and 9.
By adding 0 and 11, a differential pressure ΔP proportional to the flow velocity difference can be detected. By using the two diaphragms 10 and 11 of the diaphragm seal differential pressure gauge 26, it is important to eliminate the pressure guide tube necessary for a general differential pressure flow meter. Since the purpose is to measure a mixed two-phase fluid of steam and water, if there is a pressure guiding tube, the pressure guiding tube is clogged with water more than necessary, and stable measurement cannot be performed. In order to eliminate this, it is necessary to have a structure without a pressure guiding tube.

Next, the measurement of the pressure is performed by the pressure outlet 14.
Do with. There is a pressure outlet 14 in the horizontal direction rotated by 90 ° in the same pipe cross section as the differential pressure outlet 8 of the inlet cylindrical portion 4. The hole diameter of the pressure outlet 14 is equal to the diameter of the diaphragm. When this extraction port 14 attach the diaphragm 15 of the diaphragm seal differential pressure gauge 25, it can be measured fluid pressure P _1.

For detecting the flow velocity, sockets 18 and 19 of an ultrasonic flowmeter 24 are provided so that the ultrasonic wave passes through a center point 17 of the same pipe cross section as the differential pressure outlet 8 of the inlet cylindrical portion 4. The sockets 18 and 19 are opposed to each other at a horizontal position rotated by 90 ° in the opposite direction from the differential pressure outlet 8. The sockets 18 and 19 are provided with probes 20 and 21 for transmitting and receiving ultrasonic waves alternately, and the ultrasonic waves pass through the center point 17. As a result, the flow velocity v detected by these two probes is the average flow velocity v of the inlet cylindrical portion 4.

The detection of the flow velocity v by ultrasonic waves is performed as follows. That is, the mounting position of both probes 20 and 21 as shown in FIG. 1, rather than arranged at right angles to the flow of two-phase fluid 1 is placed to be inclined to the theta ₁ angle. The propagation speed of the ultrasonic wave increases by the flow velocity if the direction of the flow and the propagation velocity of the ultrasonic wave are in the forward direction, and decreases by the flow velocity if the propagation direction is the reverse direction. Therefore, when the measurement difference between the forward propagation time and the backward propagation time of the sound wave is obtained, the flow velocity can be determined. In the example of FIG. 1, when the fluid starts flowing, the ultrasonic wave transmitted from the probe 20 is in the forward direction and the propagation time increases, but in the probe 21, the ultrasonic wave is in the reverse direction and the propagation time decreases. Therefore, the ultrasonic wave transmitted from the probe 20 is
The time required to reach 1 is shorter than the time required for the ultrasonic wave transmitted from the probe 21 to reach the probe 20. The relationship between the time difference and the flow velocity v is as follows.

[0012]

(Equation 1)

Note that L is the distance from the tip to the tip of both probes, θ ₁ is the angle between the ultrasonic wave propagation axis and the tube center axis, t ₁ is the propagation time in the forward direction, and t ₂ is the propagation time in the reverse direction. . The important point here is that the flow velocity v and the pressure P ₁ to be detected are detected at the position of the cross section of the pressure outlet 8 on the upstream side of the differential pressure gauge 26. The three signals detected in this way are:
The signals are processed by a later-described arithmetic unit to be three types of output signals. The output signals are the total flow rate obtained by adding steam and water, the flow rate of steam, that is, only the dry saturated steam, and water, that is, three kinds of saturated water. Since the calculation is performed in this way to obtain three types of flow rates, it is important to be able to simultaneously detect three signals to be detected at the same location.

Hereinafter, first, the theoretical formula will be described, and then the calculation configuration of the calculator will be described. In the description of the theoretical formula, basically only important items will be explained, and items that have a small influence and can be ignored in measuring the flow rate will be excluded to avoid complicating the explanation. In general, the kinetic energy gives the fluid density ρ
_w, and the flow velocity v, the ρ _w v ^2/2. Assuming that the fluid pressure of the inlet cylinder 4 is P ₁ and the fluid pressure of the throttle cylinder 6 is P ₂ , the differential pressure (P ₁ −P ₂ ) can be expressed as a difference in kinetic energy.

[0015]

(Equation 2)

Here, if the ratio between the inner diameter d of the throttle cylinder 6 and the inner diameter D of the inlet cylinder 4 is expressed by the throttle diameter ratio β, the flow velocity v ₁ of the inlet cylinder 4 and the flow velocity v _{2 of the} throttle cylinder 6 Can be expressed by the following equation.

[0017]

(Equation 3)

From equations (2) and (3)

[0019]

(Equation 4)

When P ₁ -P _{2 in the} equation (4) is represented by ΔP, and a constant term is K ₂ as in the equation (5),

[0021]

(Equation 5)

[0022]

(Equation 6)

Equation (6) detects the flow velocity v ₁ of the inlet cylinder 4, squares this, and divides the differential pressure ΔP in equation (6) to obtain the wet steam density ρ flowing through the inlet cylinder 4. _This shows that _w can be calculated. The mass flow rate W flowing through the inlet cylinder 4 can be expressed by the following equation.

[0024]

(Equation 7)

From equations (6) and (7),

[0026]

(Equation 8)

Here, when the constant term is replaced with K ₁ ,

[0028]

(Equation 9)

[0029]

(Equation 10)

Equation (10) shows that the mass flow rate W can be calculated by dividing the differential pressure ΔP by the flow velocity v ₁ of the inlet cylindrical portion 4. Next, the pressure P ₁ detected at the inlet cylindrical portion 4 is converted into the density ρ _D of the dry saturated steam. This is performed using a function generator described later. The important point here is that the differential pressure ΔP
Divided by the flow velocity v ₁ is the flow rate at which the wet steam density ρ _w including the mist flows, and the flow rate of the pipe wall flow where water crawls on the inner wall of the pipe is detected by the differential pressure ΔP. It is not included because it is not possible. Therefore, by multiplying the mass flow rate w obtained from the differential pressure ΔP by the correction term, the total two-phase flow rate in which the water flowing along the pipe wall is added can be measured. This correction term can be expressed by equation (11).
Note that this equation (11) is an empirical equation created from actual measurement values.

[0031]

[Equation 11]

When the equation (11) is compared with the actual one, for example, assuming that the fluid becomes dry saturated vapor, ρ
_{Since w} = ρ _D , F ₁ = 1.00, which matches the actual case. Thus, while equation (11) is an empirical equation,
It turns out that this is a reasonable and excellent equation that matches the actual situation. Therefore, the corrected two-phase flow rate W 'is given by the equation (12).

[0033]

(Equation 12)

The two-phase flow rate W ′ includes a portion of water flowing as a mist mixed with dry saturated steam and a sum of water flowing along the tube wall. Therefore, the wet steam flow rate W
Multiplied by the following correction term gives the dry saturated steam flow rate W (steam)
Can be converted to The correction term F ₂ is strictly a complicated formula for but in practice can be expressed by equation (13).

[0035]

(Equation 13)

Accordingly, the corrected dry saturated steam flow rate W
(steam) becomes like equation (14).

[0037]

[Equation 14]

Next, the total sum W (ΣH ₂ O) of the water flowing along the mist and the pipe wall can be obtained by subtracting the dry saturated steam flow rate W (steam) from the sum flow rate W ′ of steam and water. , (15).

[0039]

(Equation 15)

Since equation (15) is inconvenient for constructing a computing unit, equation (15) is substituted with equations (12) and (14) to obtain equation (16), and this equation (16) is used. Calculate with a calculator.

[0041]

(Equation 16)

The expressions (6) to (16) described above are an important part of the present invention in terms of rationalization and simplification of the expressions. As described above, three types of detected values, that is, the differential pressure ΔP, the flow velocity v ₁ , and the pressure value P ₁ are obtained, and based on the obtained values, three types of measured values, that is, the total flow rate obtained by adding steam and water, Steam flow,
This is an arithmetic expression for obtaining the water flow rate among the total flow rates. It is needless to say that the water flow rate can be further divided as necessary to obtain the tube wall flow rate and the mist flow rate. In this case, it can be easily performed using the equations (10), (12), and (13).

Next, FIG. 5 is a block diagram of the above-mentioned arithmetic unit. The flow velocity detector 24, the pressure detector 25, and the differential pressure detector 26 shown in FIG. 5 are the same as those having the same reference numerals shown in FIGS. In FIG. 5, a signal E1, a signal E2 corresponding to the pressure, and a signal E3 corresponding to the differential pressure are simultaneously and continuously output from the flow velocity detector 24, the pressure detector 25, and the differential pressure detector 26, respectively. can get.

The differential pressure signal E3 and the flow velocity signal E1 are both input signals to the divider 31, where E3 ÷ E1 is divided and the output signal E6 is output. This signal E6 is output from the multiplier 3
6 and, at the same time, the multiplier 36 multiplies the signal E4 output from the flow rate conversion coefficient setting device 27 by E6 × E4 and outputs the output signal E13. This signal E13 is a signal corresponding to the mass flow rate W shown in the equation (10). Flow velocity v output from the flow velocity detector 24
And the signal E3 corresponding to the differential pressure output from the differential pressure detecting unit 26 are a signal E13 corresponding to the mass flow rate W, and the wet steam density ρ _w shown in the equation (6).
Is used to obtain a signal E10 corresponding to

That is, the signal E1 corresponding to the flow velocity v in FIG.
Is an input signal to the squaring operation unit 30, and is squared here to be output to the divider 32 as a signal E < ^b > 8 corresponding to v ² . At the same time, a signal E3 corresponding to the differential pressure output from the differential pressure detecting unit 26 becomes an input signal to the divider 32,
÷ E8 is divided and an output signal E9 is sent to the multiplier 33. At the same time, an output signal E5 corresponding to the density coefficient is output from the density conversion coefficient setting device 28 and becomes an input signal to the multiplier 33. Here, both signals are multiplied to obtain an output signal E10 corresponding to E9 · E5.

This is the signal E10 corresponding to the wet steam density ρ _w shown in the equation (6). This signal E10 is output from the divider 3
4 input signal. At the same time, the pressure P
Is output and sent to the function generator 29. The function generator 29 generates a signal E2 corresponding to the dry saturated vapor density ρ _D corresponding to the signal E2 corresponding to the pressure P.
7, and outputs a signal based on the graph of FIG. The signal E7 is sent to the divider 34, where E10 ÷ E7 is divided, and the output signal E11 is sent. This signal E11 is an input signal to the square root calculator 35 and the reciprocal generator 39. The signal E11 input to the square root calculator 35 is squared to become a signal E12,
7 as an input signal. A signal E13 corresponding to the mass flow rate W is simultaneously input to the multiplier 37. Both signals are multiplied by E12 and E13 to generate an output signal E14.
Is sent to the signal display 38 to display the two-phase flow rate W 'described in the equation (12).

Next, the above-mentioned reciprocal number generator 39 outputs the signal E1.
An operation of 1 ÷ E11 is performed on 1 and a signal E15 is sent to the multiplier 40. The signal E13 is also input to the multiplier 40 at the same time, where the signal E13 is multiplied by E13 and E15, and an output signal E16 is transmitted. This signal E16 is
This corresponds to the dry saturated steam flow rate W (steam) in equation (14). The signal E16 is sent to the signal display 41 to indicate the dry saturated steam flow rate W (steam). On the other hand, the signal E15 output from the reciprocal generator 39 becomes an input signal to the 1.5-th power calculator 42, the operation (E15) ^1.5 is performed, and the output signal E17 is output to the complement generator 43. This signal is subjected to the operation {1- (E15) ^1.5 } to become an output signal E18, which is an input signal to the multiplier 44. At the same time, a signal E14 corresponding to the two-phase flow rate W 'shown in the equation (12) is input to the multiplier 44.
Is input, and multiplications E14 and E18 are performed to obtain an output signal E19, which is sent to the signal display 45. The input signal E19 indicates W (ΣH ₂ O) shown in the equation (16). The above is the signal processing of the arithmetic unit.

One thing to keep in mind when measuring steam flow with a two-phase flow meter is that the detector is left in the high temperature for a long time. It is important to consider the response assuming that the detector is inspected. FIG. 3 shows an apparatus for removing and checking the differential pressure and pressure detectors without stopping the measurement fluid when checking the detectors. In this two-phase flow meter, the device having the structure shown in FIG. 3 is provided with a differential pressure detector 26A attached to the inlet cylindrical portion 4 and the throttle cylindrical portion 6, and a pressure detector 25A attached to the inlet cylindrical portion 4. I have. They are,
When the detectors 25 and 26 need to be inspected during the measurement of the wet steam flow rate, they are used to remove the differential pressure detector 26 and the pressure detector 25 without stopping the flow. At this time, handle 1 is used so that wet steam 1 flowing through the pipe does not leak out of the pipe.
2, 13 or the handle 16 is turned to close the flow paths 8, 9 or the flow path 14, and the differential pressure detectors 10, 11 and the pressure detector 15 are removed.

In FIG. 3, the main pipe side 46 of the stop valve 48 is filled with wet steam, but the space 47 on the side where the diaphragm 52 is attached is cooled because the wet steam is cooled.
A sharp pressure drop occurs. This means that the volume of steam is １ ／
It happens by shrinking to 00 and turning into water. Differential pressure detector 26A
In the structure of the pressure detector 25A , a liquid 53 for pressure transmission is sealed on the back side of the surface of the diaphragm 52 . The pressure is transmitted to the differential pressure gauge 2 by the sealed liquid 53 through the capillary tube 54.
6 and the pressure gauge 25. If the pressure of the used liquid 53 becomes negative under a high temperature, the characteristics of the liquid 53 are likely to deteriorate. For this reason, the shaft 5
1, the stop valve 48 is closed and a safety device 55 for protecting the differential pressure gauge 26 and the pressure gauge 25 for preventing the negative pressure on the surface of the diaphragm 52 is required.

The safety device 55 shown in FIG. 3 shows an embodiment of a two-phase flow meter. When the shaft 51 is turned, the valve 48 is closed and the outlet side 47 becomes a negative pressure, the spring 60 pressing the ball 59 is pushed and contracted by the external pressure 58, so that the outside air 58 is sucked and flows in through the passage 57, Diaphragm 52
Prevents the surface from becoming negative pressure. The strength of the spring 60 pressing the ball 59 can be adjusted with the adjusting screw 61. Differential pressure detector
Although removal of the pressure sensor 26 and the pressure detector 25 is omitted in FIG. 3, the bolt 68 is loosened. At this time, if the inner side 47 has the atmospheric pressure 58, it can be easily removed without sticking.

The following considerations have been made for this two-phase flow meter, and its effect is great. That is, in the measurement of the two-phase flow, the flow of water crawling on the inner wall of the pipe must be considered in addition to the mist in the steam. For this reason, if a general pressure guiding tube is adopted, the pressure guiding tube is clogged with water more than necessary, and the measurement becomes unstable. To prevent this, the differential pressure and pressure are measured using the diaphragm seal differential pressure gauge 26 not provided in the pressure guiding tube. At this time, since the hole diameter of the branch pipe is adjusted to the diameter of the diaphragm 52, a horizontal hole of 80φ, which is much larger than the hole diameter of 13φ generally used, must be formed. For this reason, water crawling on the pipe walls 4 and 6 jumps into the lateral hole 46, and the measurement of the differential pressure and the pressure becomes very unstable. In order to prevent this, the lateral hole corner 65 of the branch pipe is made as sharp as possible to improve drainage. If this is tentatively made as shown by a dotted line 66 in FIG. 3 and the corner 65 is rounded, the flow of the pipe wall wraps around, making stable measurement impossible. Since this two-phase flow meter is a flow meter that handles a pipe wall flow, the drainage effect is particularly considered.

FIG. 4 is a block diagram of an ultrasonic apparatus for measuring the flow velocity of the two-phase flow meter. That is, in the flow velocity measurement,
When it becomes necessary to check the probes 20 and 21 for transmitting and receiving ultrasonic waves, the measurement fluid 1 is not stopped and the probe 2 is not stopped.
This is a peripheral device necessary for checking 0 and 21.

With the measurement fluid 1 flowing through the main pipe 4 flowing,
If it becomes necessary to inspect the probes 20 and 21, first loosen the cap nut 62 and stop the probes 20 and 21 to stop the valve 4.
The stopper valve 48 is pushed out with the screw 51 and closed by turning the handles 22 and 23. Measurement fluid 1
Is sealed by an O-ring 64 and does not leak outside.
Further, the socket 63 is loosened and the probes 20, 21 are pulled out. A method of removing the probes 20 and 21 by this series of operations is known. However, when the measurement fluid 1 is wet steam, the main pipe side 46 after the stop valve 48 is closed is filled with wet steam, but the outlet side 47 of the stop valve 48 changes the steam into water and converts the steam to water. Since the volume contracts by 1/200, a negative pressure is created. It is not preferable to keep the tips 67 of the probes 20 and 21 under high temperature and negative pressure. Therefore, the safety device 55
To prevent negative pressure.

When the probe side 47 has a negative pressure, the spring 60 pressing the ball 59 contracts, the atmosphere 58 flows in, and the safety device 55 returns the negative pressure to the atmospheric pressure through the passage 57.
The strength of the spring 60 can be adjusted by the adjusting screw 61. Socket 63 in which probes 20 and 21 are incorporated
, And pull out the probes 20 and 21 for inspection.
Also at this time, the inside 47 is at atmospheric pressure, and it can be easily removed without sucking.

Further, the two-phase flow meter has a probe 2
The following considerations are given to the mounting of 0,21. That is, when measuring a two-phase fluid containing a large amount of water in steam,
In addition to the mist in the steam, the effects of water flowing along the pipe wall cannot be ignored. If water collides with the tips 67 of the probes 20 and 21, the flow velocity v cannot be measured accurately. In order to prevent this collision, the tips 67 of the probes 20, 21 are retracted from the inner wall surface of the tube by a dimension l. However, this is not complete in the case of tube wall flow. In such a case, it is particularly important that the branches 18, 18 with the probes 20, 21 be attached.
The purpose is to sharpen the corner 65 of the side hole connecting the main pipe 4 to the drain pipe 19 to improve drainage. In the case of measuring such a pipe wall flow, if the corner is rounded as shown by a dotted line 66, the pipe wall flow goes around and the collision of water does not disappear.

[0056]

As described above, according to the present invention,
Of the two-phase fluid, the mass flow rate of only steam, the mass flow rate of only water, and the sum of these mass flow rates can be measured simultaneously and continuously. A conventionally used steam-water separator is not required and can be configured at low cost, and wasteful consumption of fluid is prevented as compared with the conventional sampling method.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a two-phase flow meter according to the present invention.

FIG. 2 is a side view of the two-phase flow meter.

FIG. 3 is a side view of a safety device used for the two-phase flow meter.

FIG. 4 is a side view of an ultrasonic device used for the two-phase flow meter.

FIG. 5 is a configuration diagram of a calculator of the two-phase flow meter.

FIG. 6 is a graph showing a relationship between a fluid pressure and a vapor density.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Two-phase fluid 2,3 Flange 4 Inlet cylindrical part 5 Inlet conical tube 6 Restricted cylindrical part 8,9 Differential pressure outlet 10,11,15 Diaphragm 14 Pressure outlet 20,21 Probe 24 Ultrasonic flowmeter 25 Diaphragm seal pressure Total 26 Diaphragm seal differential pressure gauge 27 Flow rate conversion coefficient setting unit 28 Density conversion coefficient setting unit 29 Function generator 30 Square calculator 31, 32, 34 Divider 33, 36, 37, 40, 44 Multiplier 35 Square root calculator 38, 41, 45 Signal display 39 Reciprocal generator 42 1.5 power operator 43 Complement generator 55 Safety device

Continuing from the front page (72) Inventor Shingo Harada 2-182 Watanabe-dori, Chuo-ku, Fukuoka City, Fukuoka Prefecture Inside Kyushu Electric Power Company (72) Inventor Tatsuya Ichihara 4-28-1, Nishirokugo, Ota-ku, Tokyo Mountain Take Honeywell Co., Ltd. Kamata Factory

Claims (5)

(57) [Claims] 1. A two-phase flow meter for measuring a mass flow rate of a two-phase fluid by flowing a mixed two-phase fluid of steam and water into a conical Venturi pipe, wherein the conical Venturi pipe has an inlet. An inlet conical portion is provided following the cylindrical portion, and a constricted cylindrical portion is provided following the inlet conical portion. A high pressure side diaphragm mounting hole is provided vertically above the center of the inlet cylindrical portion, and a low pressure side diaphragm is provided. A mounting hole is provided vertically above the center of the throttle cylindrical portion, and a diaphragm seal differential pressure gauge that measures a differential pressure of the two-phase fluid from a difference between an output of the high-pressure side diaphragm and an output of the low-pressure side diaphragm attached to the mounting hole. A diaphragm mounting hole is provided in the same direction as the center of the mounting hole of the diaphragm seal differential pressure gauge of the inlet cylindrical portion and in a horizontal direction substantially 90 ° rotated from a vertical line, and attached to the mounting hole. A diaphragm seal pressure gauge for detecting the pressure of the two-phase fluid based on the output of the diaphragm provided; and two probe mounting holes opposed to the inlet cylindrical portion and approximately 60 ° horizontally with respect to the flow direction of the two-phase fluid. An ultrasonic current meter that detects the flow rate of the two-phase fluid based on the output of each probe attached to the mounting hole when the ultrasonic wave passes through the center of the cross section, and the diaphragm seal difference Differential pressure measured by manometer,
Pressure and pressure detected by the diaphragm seal pressure gauge
And input the flow velocity detected by the ultrasonic flow meter,
Mass flow of steam only, mass of water only in the two-phase fluid
Calculate the flow rate and the mass flow rate of their sum simultaneously and continuously.
That a computing unit, the mass flow rate of vapor alone of the two-phase fluid, only water mass flow rate and two-phase flow rate, characterized in that it has to be measured continuously the mass flow rate of these sums simultaneously Total. 2. The conical venturi tube according to claim 1, further comprising an outlet conical tube following the constricted cylindrical portion, wherein a length of the inlet cylindrical portion is equal to an inner diameter of the inlet cylindrical portion and the diaphragm. Equal to the sum of the hole diameter of the high pressure side diaphragm of the seal differential pressure gauge and the length of the throttle cylindrical portion is equal to the sum of the inner diameter of the throttle cylindrical portion and the hole diameter of the low pressure side diaphragm of the diaphragm seal differential pressure gauge. The two-phase flowmeter is characterized in that the inner diameter of the outlet of the outlet conical tube is equal to the diameter of the hole of the inlet cylinder. 3. The diaphragm seal differential pressure gauge and the diaphragm seal pressure gauge according to claim 2, wherein a mounting hole of the diaphragm seal pressure gauge is equal to a diameter of the diaphragm, and an angle of the mounting hole is an acute angle. A two-phase flow meter comprising a safety valve that raises the negative pressure of a diaphragm to atmospheric pressure when a stop valve disposed between holes is closed. 4. The ultrasonic flowmeter according to claim 2, wherein a tip position of the probe of the ultrasonic flowmeter is arranged at a distance of 10 to 20 mm from an inner wall surface of the tube of the inlet cylindrical portion, and an angle of a mounting hole of the probe is an acute angle. And a safety valve for preventing breakage of the probe when a stop valve of a socket for mounting the probe is closed. 5. The arithmetic unit according to claim 1, wherein the arithmetic unit divides a mass flow rate of a sum of the mass flow rates of the steam only and the water only by the differential pressure by the flow velocity.
Values to calculate by multiplying the correction term to the, the calculation of
From the measured values, the mass flow of only steam and the mass flow of water only
A two-phase flow meter characterized by calculating an amount .