JP5946025B2 - Multiphase flow meter - Google Patents

Description

  The present invention relates to a multi-phase flow meter for measuring the flow rate of a multi-phase mixed fluid in each phase.

  A multiphase flow meter is configured to measure the flow rate of these multiphase fluids for each phase when multiphase fluids such as water, oil, and gas flow in the pipeline. Conventionally, various devices have been proposed.

  In Patent Document 1, two multi-phase density meters are provided along the flow direction of the pipeline through which the multi-phase multi-phase fluid flows, and the ratio of each phase is obtained based on the relative permittivity of the multi-phase fluid according to the frequency. A multiphase flow meter is described that is configured to measure the flow rate of each phase based on the correlation method with the time required for the fluid to flow between two points.

  Patent Document 2 discloses an electromagnetic flow meter and a component ratio sensor provided along a flow direction of a pipeline through which a multiphase mixed phase fluid flows, and each mixture of measurement fluids from measurement signals of the electromagnetic flow meter and the component ratio sensor. A multi-phase flow meter having an arithmetic circuit for calculating the flow rate of the gas is described.

Japanese Patent Laid-Open No. 08-271309 Japanese Patent Laid-Open No. 10-281843

  However, these conventional multiphase flow meters all have a combination of a plurality of measuring instruments, so that the configuration of the entire apparatus becomes complicated and the cost is relatively high.

  The present invention solves these problems, and an object of the present invention is to realize a multiphase flow meter that can measure the flow rates of liquid, gas, solid particles, and the like at a relatively low cost and easily.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
A first flow rate measuring means comprising a transducer provided so as to sandwich the vertical pipe between the vertical pipe and the horizontal pipe on the outer wall of the vertical pipe adjacent to the pipe;
A second flow rate measuring means comprising a transducer provided on the outer wall of the horizontal pipe so as to sandwich the horizontal pipe and transmitting and receiving a measurement signal;
Arithmetic control means for calculating a flow parameter based on the measurement signal of the first flow measurement means and the measurement signal of the second flow measurement means;
It is the multiphase flow meter characterized by comprising.

The invention according to claim 2 is the multiphase flow meter according to claim 1,
The flow rate parameter calculation means compares the flow rate of the measurement signal of the first flow rate measurement means and the measurement signal of the second flow rate measurement means to determine the presence or absence of bubbles and the presence or absence of particles.

The invention according to claim 3 is the multiphase flow meter according to claim 2,
The flow rate parameter calculating means further calculates a bubble diameter and the number of bubbles.

The invention according to claim 4 is the multiphase flow meter according to claim 2,
The flow rate parameter calculating means further calculates the particle diameter and the number of particles.

The invention according to claim 5 is the multiphase flow meter according to claim 1,
The measurement signals of the first flow rate measurement unit and the second flow rate measurement unit are ultrasonic signals.

  Accordingly, it is possible to realize a multi-phase flow meter that can measure the flow rates of liquid and gas with a relatively inexpensive and simple configuration.

It is a configuration explanatory view showing an embodiment of the present invention. It is explanatory drawing of the state in which the bubble flow is flowing in piping. It is explanatory drawing of the formula of Stokes. It is state explanatory drawing of the slag flow in piping. It is a detection state explanatory view of slag flow. It is a measurement operation explanatory view of slag flow. It is a conceptual diagram of the signal detection in the piping and the slag flow measurement state in which the slag flow is flowing. It is explanatory drawing which represented the detection frequency of the data when changing the amount of bubbles. This is an algorithm for measuring slag flow. It is a flowchart which shows the outline | summary of the flow of operation | movement of FIG. It is a flowchart which shows the flow of operation | movement of bubble flow mode. It is explanatory drawing of the method of acquiring a reflected signal amplitude profile from a bubble. It is a profile example figure of reflected signal strength. It is an example figure of profile fitting of reflected signal amplitude. It is a flowchart which shows the flow of operation | movement of slug flow mode. It is composition explanatory drawing which shows the other Example of this invention. It is composition explanatory drawing which shows the other Example of this invention. It is composition explanatory drawing which shows the other Example of this invention. It is a comparison figure of the measurement data by the transducer from which frequency differs. It is explanatory drawing of the signal amplitude of a propagation time difference method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing the construction of an embodiment of the present invention. In FIG. 1, a pipe line 10 is composed of a vertical pipe 11 through which fluid flows upward and a horizontal pipe 12 through which fluid flows upward.

  On the outer wall of the vertical pipe 11, transducers 21 and 22 that transmit and receive measurement signals and constitute the first flow rate measuring means 20 are provided so as to sandwich the vertical pipe 11. At least one of these transducers 21 and 22 may be provided, and the flow velocity can be obtained from the reflection signal of the bubbles in the fluid by a method of measuring the velocity of particles such as the reflection correlation method or the Doppler method. However, the propagation time difference method is not suitable for measuring the flow velocity of the bubble itself.

  On the outer wall of the horizontal pipe 12, transducers 31 and 32 that transmit and receive a measurement signal and constitute the second flow rate measuring means 30 are provided so as to sandwich the horizontal pipe 12 in the vertical direction. The horizontal pipe 12 may be provided with at least one of these transducers 31 and 32, and the velocity of particles such as reflection correlation method or Doppler method is measured. For the horizontal pipe 12, the flow velocity can also be measured by the propagation time difference method using the two transducers 31 and 32.

  The transducers 21 and 22 constituting the first flow rate measuring unit 20 and the transducers 31 and 32 constituting the second flow rate measuring unit 30 are connected to an arithmetic control unit 40 functioning as a flow rate parameter calculating unit.

  The calculation control unit 40 drives and controls the transducers 21 and 22 and the transducers 31 and 32, accumulates and calculates measurement data, and displays and outputs the calculation results. A cable 50 is connected to the arithmetic control unit 40 for the purpose of supplying power from the outside, outputting a current of 4 to 20 mA to the outside, and communicating with the outside.

  FIG. 2 is an explanatory diagram of a state in which a bubble flow is flowing in the pipe. In FIG. 2, since the transducers 31 and 32 constituting the second flow rate measuring means 30 are provided so as to sandwich the horizontal pipe 12 in the vertical direction, when the amount of gas in the pipe is small, the state is almost full. Therefore, both the transducers 31 and 32 can detect the flow signal.

  In this state, the amount of gas in the pipe is several percent or less, and the pipe has a flow called a bubble flow in which small bubbles are flowing. In order to obtain the amount of bubbles in such a situation, signal processing in “bubble flow mode” is performed.

  When the amount of bubbles increases as compared with the bubble flow mode, gas accumulates on the upper side of the horizontal pipe 12, and the state becomes non-full. Therefore, the transducer 31 attached to the upper part of the horizontal pipe 12 cannot transmit ultrasonic waves into the pipe because the acoustic impedance of the pipe and gas is extremely different, and the signal cannot be detected. Since it is fixed to the lower side of the horizontal pipe 12, a signal can be detected even in a non-full state.

  At this time, the amount of bubbles is several percent or more and less than 100%, and the flow pattern in the vertical pipe 11 is alternately a large bubble that closes the entire pipe called a slag flow and a bubble flow in which small bubbles enter the liquid. It becomes a flowing mode. In order to obtain the amount of bubbles in such a situation, signal processing in “slag flow mode” described separately is performed.

  Further, when the amount of bubbles increases and the state is almost only gas, the transducer 32 fixed on the lower side cannot detect a signal. Since this state is a state where only 100% gas flows in the pipe, the gas flow rate is determined to be 100%.

  In addition, since only the transducer 31 can detect a signal and the transducer 32 cannot normally detect a signal, it is determined as a failure.

  When the reflection correlation method is used, the position of the interface between the liquid and the gas can be identified by using the transducers 31 and 32 provided so as to sandwich the horizontal pipe 12 in the vertical direction. This is a rough measure of how much the ratio of gas to liquid is at this position.

  However, since there is a slip between the gas and the liquid, it does not flow in the pipe at the same flow rate, and since the gas is compressible, it follows Boyle's law, so it is downstream from the measurement position. Depending on the state of the pipe (for example, whether the atmosphere is open or pressure is applied), it is difficult to accurately determine the volume and flow rate of the gas using only the transducers 31 and 32.

The signal processing in the bubble flow mode will be described.
The flow velocity obtained by the reflection correlation method or the Doppler method using the transducers 21 and 22 is the flow velocity due to the fluid flow velocity + bubble buoyancy (or -gravity of particles) because the transducers 21 and 22 are arranged in the vertical pipe 11. Is measured. In FIG. 2, since the flow is directed upward, the flow velocity is faster than the liquid flow rate by the buoyancy of the bubbles.

  On the other hand, since the flow velocity obtained by the transducers 31 and 32 is arranged in the horizontal pipe 12, there is no influence of bubble buoyancy, and only the fluid flow velocity is measured.

  The arithmetic control unit 40 calculates the flow velocity observed by these transducers 21, 22 and 31, 32, and calculates the flow velocity error of the transducers 21, 22 with respect to the flow velocity measured by the transducers 31, 32.

  When the flow rate measured by the transducers 31 and 32 exceeds a certain threshold and has a positive error with respect to the flow rate measured by the transducers 31 and 32, it is determined that “bubbles exist”, and the process proceeds to the bubble diameter measurement routine. This determination may include temporal elements such as how many seconds or more plus error continues, or how many data or more plus error in all data.

  In the bubble diameter measurement routine, assuming that the flow velocity error of the transducers 21 and 22 with respect to the flow velocity observed by the transducers 31 and 32 is the buoyancy due to the bubbles, the ascent rate (the flow velocity observed by the transducers 21 and 22− The bubble diameter is obtained from the flow velocity observed by the transducers B31 and B32.

  Here, the rising speed of a single bubble is determined by the balance between buoyancy and drag. This is expressed by the following equation.

ρd ・ g ・ (4/3) ・ π ・ r ³ = (Cd ・ ρd / 2) ・ π ・ r ²・ (wb-wl) ² (1)

Where the left side is buoyancy, the right side is drag,
wb: Bubble speed
wl: Liquid velocity
Cd: drag coefficient ρ: density difference
g: Gravity acceleration
r: Bubble radius.
From this equation (1)

Can guide you.
Here, the drag coefficient Cd is expressed differently depending on the Re number Reb of the bubbles.
On the other hand, Reb determines the flow state assuming the bubble size and flow that can be actually detected by this measurement system. This is a fluid in the pipe. If the bubble radius rx is 1 mm, the relative velocity ub1 between the bubble and liquid is 10 cm / s, and the kinematic viscosity coefficient ν1 of water at 25 ° C is 0.893 × 10 ^-6 m ² / s. When calculating the Re number of
Reb = 2 ・ rx ・ ub1 / ν1 (2)
Therefore, Reb becomes 22.4.

  This region is an Allen region (transition region), and the drag coefficient Cd in the Allen region can be expressed as in Equation (3).

(3)

  When this is solved for the bubble diameter r, the equation (4) is obtained.

(Four)

  As is clear from the above formula, the bubble diameter r can be obtained by obtaining the liquid flow rate wl in the horizontal pipe 12 and the bubble flow speed wb in the vertical pipe 11.

  The bubble diameter r may be calculated from the Stokes equation showing the relationship between the bubble diameter and the rising speed shown in FIG.

  In the case of particles instead of bubbles, the moving speed of the particles may be lower than the flow of fluid due to gravity. In such a case, the particle diameter can be obtained after calculating the particle measurement routine and assuming the particle density.

  Particles having a specific gravity greater than that of a fluid such as water (for example, a mineral such as coal) have a property of sinking into a liquid. As shown in FIG. 2, in the vertical pipe 11 where the transducers 21 and 22 are installed, if particles having a specific gravity larger than that of the fluid are present, the flow velocity observed by the transducers 21 and 22 is the transducers 31 and 32. Slower than the observed flow velocity. By utilizing this, the content of particles in the fluid can be measured in the same way as in the case of bubbles.

The signal processing in the slug flow mode will be described.
FIG. 4 is an explanatory diagram of the state of the slag flow in the pipe, FIG. 5 is an explanatory diagram of the detection state of the slag flow, and FIG. 6 is an explanatory diagram of the measurement operation of the slag flow.

  As shown in each of these figures, the slug flow is a flow in which huge bubbles and minute bubbles alternately flow such that a minute bubble flows after a huge bubble flows and a giant bubble flows. 5A shows a state where the transducers 21 and 22 detect small bubbles in the slag flow, and FIG. 5B shows a state where the transducers 21 and 22 detect large bubbles in the slag flow. Yes.

  In FIG. 5, if the ultrasonic path between the transducers 21 and 22 is F, in the slag flow mode, signals can be detected from the microbubbles shown in (A) by the reflection correlation method, but the giant shown in (B). A reflected signal from a simple bubble cannot be obtained. Therefore, the amount of bubbles is estimated using signals from minute bubbles detected by the reflection correlation method.

  Note that according to the reflection correlation method, a flow velocity profile as shown in FIG. 6 can be obtained by obtaining flow velocities at a plurality of positions along the ultrasonic path from the moving speed of the reflected signal from bubbles or the like. “◯” in FIG. 6 indicates measurement points. In FIG. 6, the horizontal axis indicates the distance from the transducer, and the vertical axis indicates the flow velocity.

  FIG. 7A is an enlarged view of the pipe through which the slag flow flows, and FIG. 7B is a conceptual diagram of signal detection by the transducer 21 and the transducer 22 in the slag flow measurement state shown in FIG. The first flow rate measuring means 20 intermittently detects the liquid flowing through the vertical pipe 11 and the large bubble gas, but the second flow rate measuring means 30 always detects the liquid flowing continuously through the horizontal pipe 12. Become.

  FIG. 8 is an explanatory diagram schematically showing the detection frequency of data when the amount of bubbles is changed, where (A) shows the amount of bubbles 40%, (B) shows the amount of bubbles 20%, The abscissa represents an area divided into an arbitrary number according to the distance from the transducer, and the ordinate represents the number of samplings.

  In FIG. 8, one row of data can be taken by one profile sampling. The portion where the data exists is displayed as a white cell, and the portion where the data does not exist (not measured) is a black cell. Is displayed. In the above-described slag flow mode, the portion displayed in black in FIG. 8 represents a region where large bubbles are present, and the portion displayed in white represents a region where small bubbles are present.

  Strictly speaking, the part without bubbles should be displayed in black, but the slag flow is the result of mixing a considerable amount of bubbles, so it is necessary to consider the part without bubbles substantially. There is no. According to FIG. 8, it is clear that white points increase when the amount of bubbles is small, and black points increase when the amount of bubbles is large.

  Here, for example, when 40 measurement points of one profile are present and there are less than 10 valid data, it is determined that the large bubble has passed, and there are 10 or more valid data. It is determined that the area is where small bubbles are flowing. By sampling this multiple times, the amount of gas flowing as a fluid can be estimated from the ratio of large bubbles to small bubbles.

  Actually, when performing signal processing, as shown in FIG. 7B, calculation is performed in addition to the time during which the signal is detected. There is a time part. Therefore, by calculating the bubble amount assuming that the same amount of bubbles as the measurement result of the bubble amount in the signal detection space exists in the signal non-detection space, the bubble amount in the entire fluid can be finally obtained. .

  Specifically, as shown in the algorithm at the time of slag flow measurement in FIG. 9, the ratio of the signal non-detection time (non-detection area) to the total measurement time is obtained, and the amount of bubbles therein is the same ratio as the detection area. Assuming that the amount of air bubbles is a bubble amount, assuming that the set value B of the number of data in the flowchart shown in FIG. 15 described later represents the amount of air bubbles in one detection cycle. .

FIG. 10 is a flowchart showing an outline of the operation flow of FIG.
First, based on the combination of the output signals of the transducers 31 and 32 provided in the horizontal pipe 12, the flow mode is determined.

  Specifically, first, the presence / absence of an output signal from the transducer 31 is determined (step S1). If there is an output signal from the transducer 31, then the presence / absence of the output signal from the transducer 32 is determined (step S2). If there is an output signal from the transducer 32, it is determined as a bubble flow mode, and if there is no output signal from the transducer 32, it is determined that the sensor has failed. The operation flow in the bubble flow mode will be described with reference to the flowchart of FIG.

  Even if there is no output signal from the transducer 31, the presence or absence of an output signal from the transducer 32 is subsequently determined (step S3). If there is an output signal from the transducer 32, it is determined that the mode is a slag flow mode. The operation flow in the slag flow mode will be described with reference to the flowchart of FIG.

  FIG. 11 is a flowchart showing a flow of operations in the bubble flow mode. First, the flow rate measurement result A of the first flow rate measuring means 20 is determined (step S1), and then the flow rate measurement result B of the second flow rate measuring means 30 is determined (step S2). Then, it is determined whether or not the value of the flow rate measurement result A of the first flow rate measuring unit 20 and the value of the flow rate measurement result B of the second flow rate measuring unit 30 satisfy A ≧ B (step S3).

  When A ≧ B, it is determined that there is a bubble and the process proceeds to the bubble diameter measurement routine (step S4). When A ≧ B is not satisfied, it is determined that there is a particle and the particle diameter measurement routine (step S7) Transition to processing.

  In the bubble diameter measurement routine, the bubble number counting routine (step S5) is executed to calculate the amount of bubbles (step S6), and in the particle diameter measurement routine (step S7), the particle number counting routine (step S8) is executed. The particle content is calculated (step S9). The particle size can be calculated from the Stokes equation showing the relationship between the sedimentation rate and the particle size.

  As another method for obtaining the particle size, the particle size may be obtained from the absolute value of the reflection signal amplitude by using a table (Stenzel reflection coefficient) indicating the relationship between the reflection coefficient and the particle size by regarding the particle as a rigid body. .

  In addition, a signal intensity profile routine process for obtaining a reflected signal amplitude profile from the bubble using the first flow rate measuring means 20 and the second flow rate measuring means 30 is also executed (step S10), and the processing result is set as a step. This is input and reflected in the processing of the bubble number counting routine in S5 and the particle diameter measurement routine in step S7.

  FIG. 12 is an explanatory diagram of a method for obtaining a reflected signal amplitude profile from bubbles, and is a partially enlarged view of FIG. In FIG. 12, a transducer 31 for detecting a reflected signal from bubbles is provided on the outer wall of the horizontal pipe 12.

  The acquisition of the reflected signal amplitude profile is performed completely separately from the flow rate measurement, and the reflected signal amplitude profile represents the amplitude of the reflected signal at each position in the pipe estimated from the propagation time of the ultrasonic wave.

  FIG. 13 is a profile example of the reflected signal intensity. In FIG. 13, the horizontal axis represents the ultrasonic propagation distance in the pipe, and the vertical axis represents the amplitude (relative value) of the reflected signal of the ultrasonic wave from the bubble. A propagation distance of 0 m represents the inner wall of the pipe on the transducer side.

  By the way, in the bubble number calculation routine (step S5) in the flowchart of FIG. 11, the number of bubbles is determined based on the reflection signal amplitude profile and bubble diameter information obtained up to the previous process. Specifically, the number of bubbles is calculated from the fitting with the profile of the reflected signal amplitude using a calculation formula using the bubble diameter and the number of bubbles as parameters. As a calculation formula, for example, the following formula (5) is conceivable.

In equation (5), a is the amplitude of the ultrasonic reflected signal, A is the intensity of the ultrasonic reflected signal, I ₀ is the intensity of the ultrasonic incident signal, S is the bubble cross-sectional area, and the radius of the bubble is r. Πr ² . n is the bubble number density per unit volume, x is the propagation distance of the ultrasonic wave, and dx is the waveform clipping range at a certain time. Expression (5) means that the reflection intensity A is expressed by (transmitted wave intensity up to a certain position) × (ultrasound reflectivity at a certain position) × (other terms).

  Here, the other terms are an ultrasonic absorption term and diffusion term of fluid accompanying propagation of ultrasonic waves, background noise, and the like. The background noise may be a measured value of a signal amplitude observed when no ultrasonic wave is emitted.

The only unknown parameter in equation (5) is the bubble number density n. The bubble number density n may be determined by fitting with a reflection signal amplitude profile as shown in FIG. 14, for example. For the fitting, for example, a least square method is used. In addition, the fitting by a relative value may be sufficient and the absolute value of a reflected signal amplitude is not required. This is not only necessary to know I ₀ and dx in the formula (5), but also has a great merit that it is not necessary to consider the contact area between the pipe and the transducer, the type and thickness of the pipe, and the presence or absence of deposits. is there.

  FIG. 14 is an example of profile fitting of reflected signal amplitude. In FIG. 14, the horizontal axis represents the ultrasonic propagation distance in the pipe, and the vertical axis represents the amplitude (relative value) of the reflected signal of the ultrasonic wave from the bubble. In FIG. 14, the fitting is performed with the bubble ratio (void ratio), but since the bubble diameter is already known, the fitting may be performed with either the number of bubbles or the amount of bubbles.

  Since the bubble diameter and the number of bubbles can be calculated by the above process, the amount of bubbles can be calculated as shown in the flowchart of FIG. The final output can be any of flow velocity, flow rate, bubble diameter, bubble number, and bubble volume.

  FIG. 15 is a flowchart showing an operation flow in the slug flow mode. First, a flow velocity profile is measured (step S1), and then a count value A of the number of flow velocity profile formation data is obtained (step S2). Then, it is determined whether or not the count value A and the data number setting value B set separately in step S3 are A ≧ B (step S4).

  When A ≧ B, the process proceeds to the flow velocity profile data process (step S5), and when A ≧ B, the process proceeds to the bubble region process (step S6).

  When the processing of the flow velocity profile data and the processing of the bubble region are finished, the process proceeds to the processing of the average flow velocity profile (step S7).

  Thereafter, the bubble region frequency is obtained (step S8), and the bubble amount is further calculated (step S9).

With these configurations, not only the flow rate of fluid as an ultrasonic flow meter, but also various flow parameters such as the measurement of bubble diameter and number of bubbles and the flow rate of bubbles, with a simple configuration similar to existing ultrasonic flow meters. It can be measured simultaneously and is economical.
Further, the presence / absence of bubbles and the presence / absence of particles can be detected by using the flow determination routine.

  In the above embodiment, the example of obtaining the bubble amount and the particle amount with respect to the bubbles and particles has been described. However, it is not always necessary to obtain the bubble amount, and only the bubble / particle diameter or the number of bubbles / particles may be output. .

  Further, instead of measuring the flow rate by the reflection correlation method in the horizontal pipe 12, the flow rate of the liquid may be measured by the propagation time difference method in the vertical pipe 11 or the horizontal pipe 12 to obtain the bubble flow rate.

  FIG. 16 is a structural explanatory view showing another embodiment of the present invention, and the same reference numerals are given to the portions common to FIG. In FIG. 16, the pipe line 10 includes a vertical pipe 11 in which the fluid flows downward and a horizontal pipe 12 in which the fluid that flows downward flows in the horizontal direction.

  By configuring as shown in FIG. 16, it is also possible to individually determine bubbles and particles. In the downstream horizontal pipe 12, particles having a density higher than that of the liquid are moved closer to the bottom due to centrifugal force, and bubbles having a lower density are further moved toward the upper side due to buoyancy.

  The transducers 31 and 32 provided so as to sandwich the horizontal pipe 12 in the vertical direction can detect the frequency of the reflected signal and how often the reflected signal is based on the signal detection frequency and the position information.

  Therefore, if there are many reflection signals on the bottom side of the horizontal pipe 12, it can be determined as particles, and if there are many reflection signals on the upper side, it can be determined as bubbles, and based on these, the gas flow rate and particle amount can be obtained individually. It becomes possible.

Note that the bubble diameter can be measured only by the transducers 21 and 22 provided so as to sandwich the vertical pipe 11 between the outer walls of the vertical pipe 11.
Specifically, the following two ways can be considered.
a) A method of operating the propagation time difference method and the reflection correlation method or the Doppler method in a hybrid manner using the transducers 21 and 22 (hereinafter referred to as a hybrid operation method).
b) A method of measuring the two detection ends of the transducers 21 and 22 by a reflection correlation method or a Doppler method using different frequencies (hereinafter referred to as a method of measuring at different frequencies).

  According to these methods, it is not necessary to attach a transducer to the horizontal pipe 12, so that the entire apparatus can be simplified and the cost can be reduced. In addition, there is an effect that the restriction on the pipe that the horizontal pipe and the vertical pipe are necessary is eliminated. can get.

a) Method of operating by hybrid The ultrasonic flowmeter can measure the flow velocity of the fluid alternately by the reflection correlation method or the Doppler method and the propagation time difference method. Whereas the reflection correlation method or Doppler method calculates the flow velocity based on the reflected signal from the bubble, the propagation time difference method obtains the flow velocity from the ultrasonic propagation time difference on the upstream side and the downstream side. It is measuring.

  FIG. 17 is an explanatory diagram showing the configuration of another embodiment of the present invention. The vertical pipe 11 is used to measure the bubble rising speed and measure the bubble diameter. In FIG. 17, on the outer wall of the vertical pipe 11, a transducer 21 constituting an ultrasonic flowmeter capable of transmitting and receiving a measurement signal and measuring the reflection correlation method or the Doppler method and the propagation time difference method as the first flow rate measuring means 20, 22 is provided so as to sandwich the vertical pipe 11.

  The flow velocity obtained by the reflection correlation method or the Doppler method is (fluid flow velocity) + (flow velocity corresponding to bubble buoyancy). On the other hand, since the flow velocity obtained by the propagation time difference method is the flow velocity of the fluid, the difference between the two flow velocities represents the rising speed of the bubbles. Thereafter, the bubble diameter is calculated according to the flowchart of FIG.

b) Method of measuring at different frequencies FIG. 18 is also an explanatory diagram of a configuration showing another embodiment of the present invention. In FIG. 18, transducers 21 and 22 having different driving frequencies are provided on the outer wall of the vertical pipe 11 so as to sandwich the vertical pipe 11. The high frequency transducer 21 can generate ultrasonic waves of several hundred kHz to several tens of MHz, and the low frequency transducer 22 can generate ultrasonic waves of several tens of kHz to several MHz.

Since the high frequency transducer 21 has a short ultrasonic wavelength, it is possible to obtain a reflection signal from the microbubbles with negligible buoyancy. Of course, a signal from a large bubble is also obtained.
On the other hand, since the low frequency transducer 22 has a long wavelength, a reflected signal can be obtained only from bubbles of a certain size, and the microbubbles are transmitted without being reflected.

  FIG. 19 is a comparison diagram of measurement data obtained by transducers having different frequencies. When the respective flow velocity profiles are compared, FIG. 19 (A) is obtained. The profile acquired by the low-frequency transducer 22 is measured as (original fluid flow velocity) + (flow velocity due to buoyancy of large bubbles).

  On the other hand, the profile acquired by the high frequency transducer 21 is measured as (original fluid flow velocity) + (flow velocity due to buoyancy of microbubbles to large bubbles). Therefore, in both the low frequency transducer 21 and the high frequency transducer 22, the flow velocity is calculated more positively than the flow velocity of the original fluid, but the measurement result at the high frequency includes the reflected signal from the microbubbles, It is slower than the average flow velocity at low frequency (the flow velocity of only large bubbles).

  In the reflection correlation method, by counting effective data correlated with two or more reflected signal waveforms, it can be expressed as a histogram as shown in FIGS. As described above, the center value of the histogram of the flow velocity profile obtained by the high frequency transducer and the low frequency transducer represents the average value of the flow velocity. Therefore, when each histogram is subtracted, the difference represents only the reflected signal from the microbubbles. Since the rising speed of microbubbles is negligibly small, this can be regarded as the speed of the fluid.

  As apparent from the above, the flow velocity profile obtained by the low-frequency transducer 22 is set as a flow velocity from a representative bubble diameter, and the flow velocity of the microbubbles obtained from the difference in the histogram is set as the flow velocity of the fluid. The typical bubble rising speed can be calculated from the difference in flow velocity. The subsequent process is the same as in FIG.

  Note that the liquid flow measurement result of another flow meter such as a Coriolis flow meter may be used instead of the flow measurement by the reflection correlation method in the horizontal pipe.

Moreover, you may obtain | require the signal attenuation | damping in bubble flow mode using a propagation time difference method.
This is a modification of the process of calculating the bubble amount from the acquisition of the reflected signal amplitude profile of FIG. FIG. 20 is an explanatory diagram of the signal amplitude of the propagation time difference method, (A) is a conceptual diagram of the propagation time difference method, and (B) is a signal amplitude diagram. As shown in FIG. 20, the amplitude of the transmitted wave observed by the propagation time difference method decreases as the amount of bubbles increases. The amount of bubbles can also be obtained from the amount of decrease in amplitude. In this case, the amplitude t of the transmission waveform is obtained by the following equation (6) from the relationship with the transmitted light intensity T.

  When obtaining the bubble amount from the amplitude of the transmission waveform, unlike the case of the reflection amplitude profile, it is necessary to know in advance the amplitude of the transmission waveform when no bubble is present. Therefore, the amplitude of the transmission waveform when bubbles do not exist is obtained by either of the following methods 1) or 2).

1) The absolute value of the amplitude is calculated from equation (5). In this case, since I ₀ is a value determined by the piping conditions, it is stored in the arithmetic control unit 40 as a data table or calculated from a corresponding calculation formula.

  2) As a more reliable method, there is a method in which the amplitude of the transmission waveform when there is no bubble is left in the memory of the converter. For example, it may be acquired when the process stops (after a while, the bubbles no longer exist in the fluid).

  As described above, according to the present invention, it is possible to realize a multiphase flow meter that can measure the flow rates of liquid, gas, solid particles, and the like with a relatively inexpensive and simple configuration.

DESCRIPTION OF SYMBOLS 10 Pipe line 11 Vertical piping 12 Horizontal piping 20 1st flow measurement means 21, 22 Transducer 30 2nd flow measurement means 31, 32 Transducer 40 Operation control part 50 Cable

Claims (5)

A first flow rate measuring means comprising a transducer provided so as to sandwich the vertical pipe between the vertical pipe and the horizontal pipe on the outer wall of the vertical pipe adjacent to the pipe;
A second flow rate measuring means comprising a transducer provided on the outer wall of the horizontal pipe so as to sandwich the horizontal pipe and transmitting and receiving a measurement signal;
A flow parameter calculation means for calculating a flow parameter based on the measurement signal of the first flow measurement means and the measurement signal of the second flow measurement means;
A multi-phase flow meter characterized by comprising   The flow rate parameter calculation means compares the flow rate of the measurement signal of the first flow rate measurement means and the measurement signal of the second flow rate measurement means to determine the presence or absence of bubbles and the presence or absence of particles. The multiphase flow meter according to 1   The multiphase flow flow meter according to claim 2, wherein the flow rate parameter calculating means further calculates a bubble diameter and a number of bubbles.   The multi-phase flow meter according to claim 2, wherein the flow parameter calculation means further calculates a particle diameter and a number of particles.   The multiphase flow meter according to claim 1, wherein the measurement signals of the first flow rate measuring means and the second flow rate measuring means are ultrasonic signals.