JP6504594B2 - Coriolis mass flowmeter - Google Patents

Description

  The present invention relates to a Coriolis mass flowmeter which measures the mass flow rate of fluid.

  The Coriolis mass flowmeter vibrates a tube through which fluid flows, and measures the mass flow rate of the fluid flowing through the tube from the phase difference between vibration detection signals at two different points upstream and downstream of the tube. As a method of detecting a phase difference in a Coriolis mass flowmeter, one using a digital detection method is known (see, for example, Patent Document 1). The digital detection method samples each of detection signals obtained by a sensor (pickup coil) provided on the upstream side and a sensor provided on the downstream side at the same timing and converts them into digital signals, and converts these into digital signals. It is a detection method which detects the phase difference of a detection signal by giving predetermined signal processing to it. Here, as signal processing performed for detection of the phase difference of the detection signal, DFT (Discrete Fourier Transform: discrete Fourier transform) processing and Hilbert transform processing may be mentioned.

  It is known that when air bubbles are mixed in the fluid of the fluid to be measured during measurement using a Coriolis mass flow meter, an error occurs in the measurement result of the Coriolis mass flow meter. For example, Patent Document 2 discloses a diagnostic technique for diagnosing that air bubbles are mixed in the fluid of the fluid to be measured. In the conventional diagnostic technology, fluctuation is calculated based on the detection signal obtained by the upstream sensor or the downstream sensor, and a state value representing the state of air bubbles in the fluid to be measured is calculated based on the calculated fluctuation. The state of the air bubble is determined based on the determined state value.

JP, 2010-203921, A JP, 2011-22020, A

  In the conventional diagnostic technique described above, when the amount of gas mixed in the fluid to be measured (the ratio of the gas of the gas-liquid ratio) increases, the diagnostic accuracy decreases. This is because as the gas ratio of the gas-liquid ratio of the fluid to be measured increases, the fluctuation based on the detection signal obtained by the upstream sensor or the downstream sensor decreases. In addition, the measurement error also increases as the gas ratio of the gas-liquid ratio increases. Therefore, it is preferable that the gas-liquid ratio of the fluid to be measured can be estimated.

  The present invention has been made in consideration of such circumstances, and an object thereof is to provide a Coriolis mass flowmeter capable of estimating the gas-liquid ratio of a fluid to be measured.

(1) One aspect of the present invention is a Coriolis mass flowmeter that measures the mass flow rate of the fluid based on the phase difference between the output signals of the first and second sensors that detect the vibration of the measurement tube through which the fluid flows. And an air-liquid ratio calculation unit for calculating an air-liquid ratio based on the calculated amplitude, the amplitude calculation unit calculating an amplitude based on the output signal of the first or second sensor. Coriolis mass flowmeter.

(2) One aspect of the present invention is the Coriolis mass flowmeter according to the above (1), further including a gas mixing coefficient calculation unit that calculates a gas mixing coefficient that is an average of the calculated amplitudes; The part is a Coriolis mass flowmeter which uses the calculated gas mixing coefficient to calculate the ratio of the gas and liquid.

(3) One aspect of the present invention is the Coriolis mass flowmeter according to any one of the above (1) or (2), wherein the measured value is based on the amplitude of the output signal of the first or second sensor. The Coriolis mass flowmeter further includes a correction unit that corrects the mass flow rate of the fluid.

(4) One aspect of the present invention is an alarm signal according to a result of comparing the calculated ratio of gas and liquid with a predetermined threshold value in the Coriolis mass flowmeter according to any one of the above (1) to (3) The Coriolis mass flowmeter further includes a notification unit that outputs

  According to the present invention, the effect that the gas-liquid ratio of the fluid to be measured can be estimated is obtained.

It is a block block diagram of the Coriolis mass flowmeter 1 concerning a 1st embodiment of the present invention. It is a supplementary explanatory view about Coriolis mass flowmeter 1 concerning a 1st embodiment of the present invention. It is a supplementary explanatory view about Coriolis mass flowmeter 1 concerning a 1st embodiment of the present invention. It is a block block diagram of the estimation part 100 which concerns on 1st Embodiment of this invention. It is a graph which shows the structural example of gas-liquid ratio calculation information which concerns on 1st Embodiment of this invention. It is a block block diagram of the Coriolis mass flowmeter 2 concerning a 2nd embodiment of the present invention. It is a block block diagram of correction | amendment part 300 which concerns on 2nd Embodiment of this invention. It is a graph for demonstrating the relationship between the volumetric flow ratio β and the flow measurement deviation ratio γ _{meas according} to the second embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First Embodiment
FIG. 1 is a block diagram of the Coriolis mass flowmeter 1 according to the first embodiment. As shown in FIG. 1, the Coriolis mass flowmeter 1 according to the first embodiment is roughly divided into a detection unit 10, a conversion unit 20, and an estimation unit 100. The detection unit 10 vibrates the measurement tube T (see FIG. 2) through which the fluid as the measurement target flows, and detects the vibration of the upstream and downstream and the temperature of the measurement tube T. The conversion unit 20 obtains the phase difference of the detection signals SA and SB detected by the detection unit 10, and obtains the mass flow rate of the fluid flowing through the measurement tube T. The estimation unit 100 estimates the gas-liquid ratio of the fluid to be measured using the digital signals DA1 and DA2 generated by the conversion unit 20.

  FIG. 2 is a block diagram showing the configuration of the detection unit 10. As shown in FIG. As shown in FIG. 2, the detection unit 10 includes an exciter 11, an upstream sensor 12 (first sensor), and a downstream sensor 13 (second sensor) provided around the measurement tube T through which the fluid flows. , And a temperature sensor 14. In the present embodiment, in order to simplify the description, it is assumed that the measurement tube T is a straight tube type fixed and supported by the support members SP1 and SP2.

  The vibrator 11 vibrates the measurement tube T in a predetermined vibration mode in accordance with the drive signal DR1 output from the conversion unit 20 shown in FIG. FIG. 3 is a view showing an example of the vibration mode of the measurement tube T. As shown in FIG. For example, the vibrator 11 vibrates the measuring tube T in a primary mode (a vibration mode in which a node of vibration appears only in a portion fixed and supported by the support members SP1 and SP2) shown by attaching symbols M1 and M2 in FIG. Let When fluid flows in the measurement tube T in a state where such vibration is applied, the measurement tube T is, for example, shown in FIG. 3 in a secondary mode (symbols of vibration indicate support members SP1 and SP2). Vibrate in the vibration mode that appears in the part fixedly supported by and the middle position thereof. In actuality, the measurement tube T vibrates in a vibration mode in which the two vibration modes are superimposed.

  The upstream sensor 12 is fixed in the vicinity of the support member SP1 to detect the vibration on the upstream side of the measurement tube T. The detection result of the upstream sensor 12 is output to the conversion unit 20 as a detection signal SA. The downstream sensor 13 is fixed in the vicinity of the support member SP2 to detect the downstream vibration of the measurement tube T. The detection result of the downstream sensor 13 is output to the conversion unit 20 as a detection signal SB.

  The temperature sensor 14 is fixed on the measurement tube T in the vicinity of the support member SP2 to detect the surface temperature of the measurement tube T. The detection result of the temperature sensor 14 is output as a detection signal ST1 to the conversion unit 20, and is used to prevent a measurement error of mass flow due to temperature fluctuation.

On the other hand, in the conversion unit 20, the clock signal oscillator 21 generates a timing signal Tc having a predetermined sampling cycle regardless of the vibration of the measurement tube T. Detection signals SA, for example, is output by A · sin (ωt ₀₎ becomes form the track-and-hold (T & H) circuit 22, where the detection by the timing signal Tc for determining the time point of the sampling signal SA are sequentially sample / hold at each time point Be done. Here, A is an amplitude, ω is an angular frequency, and t ₀ is an arbitrary time point.

  The detection signal SA held by the T & H circuit 22 is output to an A / D converter 23, where it is sequentially converted to a digital signal DA and output to a low pass filter (LPF) 24 processed in digital form. The LPF 24 removes frequency components higher than the vicinity of the vibration frequency of the measurement tube T, and outputs the result as the digital signal DA1 to the differential filter 25, the phase calculation unit 26, and the estimation unit 100. The LPF 24 is not necessarily provided, and the output signal (digital signal DA) of the A / D converter 23 may be directly output to the differential filter 25, the phase calculating unit 26, and the estimating unit 100. Further, instead of the LPF 24, a band pass filter may be provided to pass the vibration frequency.

The differential filter 25 is a digital filter that converts an input signal (digital signal DA1) into an output signal with a phase difference of 90 ° by differentiating the input signal (digital signal DA1), and basically the digital signal DA2 in the form of A · cos (ωt ₀ ) It is output to the calculation unit 26 and the estimation unit 100.

The phase operation unit 26 calculates the ratio [A · sin (ωt ₀ ) / A · cos (ωt ₀ ) = tan (ωt ₀ )] between the digital signal DA1 and the digital signal DA2 and calculates tan ⁻¹ thereof. Thus, the phase signal θ _A1 (= ωt ₀ ; first phase) of the detection signal SA is calculated. In this calculation, when the ratio (DA1 / DA2) of the value of the phase signal theta _A1 is near 90 °, so can not be accurately calculating, in the case of such a ratio, omitting the calculation of the phase signal theta _A1 It is also possible to do (do not calculate tan ^-1 ).

Further, the detection signal SB is output to the T & H circuit 27 in the form of, for example, B · sin (ωt ₀ + ΔΦ), where the detection signal SB is sequentially sampled and held at each time by the timing signal Tc which determines the time of sampling. . Here, B represents the amplitude, and ΔΦ represents the phase difference with respect to the detection signal SA at time t ₀ .

  The detection signal SB held by the T & H circuit 27 is output to the A / D converter 28, where it is sequentially converted into the digital signal DB and output to the LPF 29 processed in digital form. The LPF 29 has the same configuration as the LPF 24, and the gain characteristic and the group delay characteristic are also selected in common. The LPF 29 removes frequency components higher than the vicinity of the vibration frequency of the measurement tube T, and outputs the result to the differential filter 30 and the phase calculator 31 as a digital signal DB1. The LPF 29 is not necessarily provided, and the output signal (digital signal DB) of the A / D converter 28 may be directly output to the differential filter 30 and the phase operation unit 31. Further, instead of the LPF 29, a band pass filter may be provided to pass the vibration frequency.

The differential filter 30 is a digital filter that converts an input signal (digital signal DB1) into an output signal with a phase difference of 90 ° by differentiating the input signal (digital signal DB1), and basically a digital signal DB2 in the form of B · cos (ωt ₀ + ΔΦ) It is output to the phase calculator 31. The phase calculation unit 31 calculates the ratio [B · sin (ωt ₀ + ΔΦ) / B · cos (ωt ₀ + ΔΦ) = tan (ωt ₀ + ΔΦ)] between the digital signal DB1 and the digital signal DB2, and the tan ⁻¹ The phase signal θ _B1 (= ωt ₀ + ΔΦ; second phase) of the detection signal SB is calculated.

The phase difference calculation unit 32 calculates the difference between the phase signal θ _A1 sequentially output from the phase calculation unit 26 and the phase signal θ _B1 sequentially output from the phase calculation unit 31 (= phase difference ΔΦ) to obtain a phase difference. The signal θ ₁ is sequentially output. The phase difference signal theta ₁ is in proportion to the mass flow rate of the fluid to be measured, it is outputted to the mass flow rate calculation unit 41.

The time delay element 33 delays the phase signal θ _A1 (= ωt ₀ ) output from the phase calculator 26 by one sample period Tc and outputs it. Thus, at time _{t 0,} 1 sample point before the phase signal _{θ A1 '(= ωt -1;} t -1 is the previous sampling time) is output to the frequency calculation unit 34. The frequency calculator 34 performs an operation [(ωt ₀ −ωt ₋₁ ) / 2πTc = f _C ] for dividing the difference between the phase signals θ _A1 and θ _A1 ′ by 2πTc, and excites at time t ₀ . The frequency f _C (the frequency of the detection signal SA of the upstream sensor 12) is determined. The averaging circuit 35 obtains the vibration frequency f _C ′ of the average of the vibration frequency f _C obtained at a large number of sampling points, and outputs the vibration frequency f _C ′ to the density calculator 40 and the mass flow calculator 41.

Note that although the frequency calculation unit 34 described above calculates the excitation frequency f _C based on the displacement amount [(ωt ₀ −ωt ₋₁ ) / 2πTc = f _C ] of the phase signal θ _A1 that is the first phase, The vibration frequency f _C (in this case, the frequency of the detection signal SB of the downstream sensor 13) is calculated based on the displacement amount of the phase signal θ _B1 which is the second phase output from the phase calculation unit 31. It is good.

  Further, the detection signal SA is input to the excitation circuit 36, and an excitation voltage (drive signal DR1) corresponding to the detection signal SA is output to the vibrator 11 to drive the vibrator 11 in, for example, a sine wave. On the other hand, the detection signal ST1 is outputted from the temperature sensor 14 to the T & H circuit 37, and the large number of detection signals ST1 held by the timing signal Tc for determining the time of sampling are converted into digital signals by the A / D converter 38. The signal is output to the averaging circuit 39, and is averaged here to be output as the temperature signal ST2 to the density calculator 40 and the mass flow calculator 41.

The density calculator 40 calculates the density D of the fluid to be measured from the following arithmetic expressions (1) and (2) based on the excitation frequency f _C ′ and the temperature signal ST 2 and outputs the density D to the mass flow calculator 41 . In the following arithmetic expressions (1) and (2), f _r is a resonance frequency in a state where the fluid to be measured fills the measurement tube T at a reference temperature, and f ₀ is a resonance frequency in a state where the measurement tube T is empty , K ₁ and K ₂ are constants.
D = K ₂ (f ₀ ² −f _r ² ) / _fr ^{2 2} (1)
In addition, f _r = f _C ′ / (1 + K ₁ · ST 2) (2)

The mass flow rate calculation unit 41 calculates the mass flow rate Q from the following arithmetic expression (3) based on the density D, the excitation frequency f _C ', the phase difference signal θ ₁ (= ΔΦ), and the temperature signal ST2. In the following operational expression (3), _{K 3} is a constant, f (ST2) is a correction term of the temperature, f (D) is a correction term of density.
Q = K ₃ · f (ST 2) · f (D) · tan θ ₁ / f _C '(3)

  Next, the estimation unit 100 will be described with reference to FIG. FIG. 4 is a block diagram of the estimation unit 100. As shown in FIG. The digital signals DA1 and DA2 are input from the conversion unit 20 to the amplitude calculation unit 111. The amplitude calculation unit 111 squares the digital signals DA1 and DA2 and adds them as shown in the following arithmetic expression (4), calculates the square root of the sum as the addition result, and obtains the amplitude AmpS. The amplitude calculation unit 111 outputs the amplitude AmpS to the gas mixing coefficient calculation unit 112.

  The gas mixing coefficient calculation unit 112 calculates the gas mixing coefficient AF from the amplitude AmpS according to the following arithmetic expression (5). The gas mixing coefficient calculation unit 112 outputs the gas mixing coefficient AF to the gas-liquid ratio calculation unit 113. In the following arithmetic expression (5), AmpS (k) is an amplitude AmpS at the kth sampling time when the arbitrary sampling time is the first sampling time (k = 1), and k is from 1 to It is a natural number up to N. According to the following arithmetic expression (5), the gas mixing coefficient AF is an average of the amplitudes AmpS for N times from an arbitrary sampling time (first sampling time).

The gas-liquid ratio calculation unit 113 calculates the gas-liquid ratio OutA based on the gas mixing coefficient AF. The gas-liquid ratio calculation unit 113 uses gas-liquid ratio calculation information stored in the gas-liquid ratio calculation information storage unit 114 for calculation of the gas-liquid ratio OutA. FIG. 5 is a graph showing a configuration example of gas-liquid ratio calculation information. As shown in FIG. 5, the gas-liquid ratio calculation information indicates a one-to-one correspondence between the gas mixing coefficient AF and the gas-liquid ratio OutA. For example, for a single gas mixing coefficients AF _X, is one of the gas-liquid ratio OutA _X is associated. The gas-liquid ratio calculation information is prepared in advance and stored in the gas-liquid ratio calculation information storage unit 114. The gas-liquid ratio calculation information may, for example, actually perform measurement for obtaining the gas-liquid ratio calculation information, and obtain the measurement result. The gas-liquid ratio calculation unit 113 reads out from the gas-liquid ratio calculation information storage unit 114 a gas-liquid ratio OutA that is associated with the gas mixing coefficient AF input from the gas mixing coefficient calculation unit 112. The gas-liquid ratio calculation unit 113 outputs the gas-liquid ratio OutA read from the gas-liquid ratio calculation information storage unit 114.

  The gas-liquid ratio calculation unit 113 may calculate the void ratio as the gas mixing ratio when the gas mixing coefficient AF decreases by a certain value. For example, one-to-one correspondence between the gas mixing coefficient AF and the void ratio may be used as gas-liquid ratio calculation information such that the void ratio is 10% when the gas mixing coefficient AF is reduced by 50%.

  The gas-liquid ratio OutA output from the gas-liquid ratio calculation unit 113 is input to the notification unit 131. The threshold storage unit 132 stores the threshold Th. The notification unit 131 reads the threshold Th from the threshold storage unit 132, and compares the gas-liquid ratio OutA with the threshold Th. The notification unit 131 outputs an alarm signal OutB according to the result of comparing the gas-liquid ratio OutA with the threshold value Th. For example, when it is determined that the gas-liquid ratio OutA exceeds the threshold Th, the notification unit 131 outputs an alarm signal OutB. The alarm signal OutB is output in a manner known to the user. For example, an alarm sound may be generated or an alarm lamp may be turned on by the alarm signal OutB.

  The threshold value Th may be a threshold value of the void ratio, and the alarm signal OutB may be output when the gas-liquid ratio OutA which is the void ratio exceeds the threshold value Th of the void ratio. For example, the threshold value Th of the void ratio may be 1%, and the alarm signal OutB may be output when the void ratio gas-liquid ratio OutA exceeds 1%. As a result, it is possible to notify the user that the void ratio exceeds the threshold value Th as the gas-liquid ratio of the fluid to be measured.

  As described above, in the Coriolis mass flowmeter 1 according to the first embodiment, the gas-liquid ratio associated with the amplitude AmpS of the detection signal SA of the upstream sensor 12 is calculated. The fluid ratio can be estimated.

  Although the above estimation unit 100 calculates the amplitude of the detection signal SA of the upstream sensor 12 using the digital signals DA1 and DA2, the downstream sensor 13 uses the digital signals DB1 and DB2 as the amplitude AmpS. The amplitude of the detection signal SB may be calculated.

  In addition, the estimation unit 100 may calculate the gas mixing coefficient AF by the following arithmetic expression (6) instead of the above arithmetic expression (5). In the following arithmetic expression (6), AmpSA (k) uses the digital signals DA1 and DA2, and the amplitudes AmpS and AmpSB (k) calculated by the above arithmetic expression (4) use the digital signals DB1 and DB2. It is an amplitude calculated in the same manner as the amplitude AmpS of the arithmetic expression (4).

  In addition, although the estimation unit 100 described above uses the average of the amplitudes AmpS for a plurality of times as the gas mixing coefficient AF, the amplitude AmpS may be used as the gas mixing coefficient AF.

Second Embodiment
Next, the Coriolis mass flowmeter 2 according to the second embodiment will be described. FIG. 6 is a block diagram of the Coriolis mass flowmeter 2 according to the second embodiment. 6, the same components as in FIG. 1 will be assigned the same reference numerals and explanation thereof will be omitted.

  As shown in FIG. 6, the Coriolis mass flowmeter 2 according to the second embodiment has a configuration in which a correction unit 300 is added to the Coriolis mass flowmeter 1 according to the first embodiment. The mass flow rate Q output from the mass flow rate calculation unit 41 and the digital signal DA output from the conversion unit 20 are input to the correction unit 300. The correction unit 300 corrects the mass flow rate Q input from the mass flow rate calculation unit 41 based on the amplitude of the digital signal DA input from the conversion unit 20. The amplitude of the digital signal DA corresponds to the amplitude of the detection signal SA of the upstream sensor 12. The method of correcting the mass flow rate Q will be described below.

FIG. 7 is a block diagram of the correction unit 300. As shown in FIG. The flow rate measurement deviation rate calculation unit 311 calculates the effective value A _eff of the voltage of the detection signal SA of the upstream sensor 12 according to the following arithmetic expression (7). In the following arithmetic expression (7), _Ai is a voltage of the detection signal SA of the upstream sensor 12. Flow measurement deviation calculating unit 311 uses the digital signals DA as the signal voltage A _i of the detection signal SA. In the following arithmetic expression (7), N is the number of data of the digital signal DA.

The flow rate measurement deviation rate calculation unit 311 calculates the volumetric flow rate ratio β by the following arithmetic expression (8). The volumetric flow ratio β corresponds to the gas-liquid ratio of the fluid to be measured. In the following equation (8), A _eff is an effective value calculated by the above equation (7), and a and b are constants. The constants a and b are, for example, actually measured to obtain a and b, and calculated by the least squares method from the measurement results.
β = (A _eff −b) / a (8)

The volumetric flow ratio β is the ratio of the volumetric flow of the gas phase to the total volumetric flow of the fluid flowing in the measuring tube T. The volumetric flow ratio β is defined by the following definition equation (9). In the following definition formula (9), Q _G is the volumetric flow rate of the gas phase flowing in the measuring tube T [m ³ / s], and Q _L is the volumetric flow rate of the liquid phase flowing in the measuring tube T [m ³ / S].
β = Q _G / (Q _G + Q _L ) (9)

Flow measurement deviation calculating unit 311, by the following arithmetic expression (10), to calculate the flow rate measurement deviation rate gamma _est. The flow rate measurement deviation rate calculation unit 311 outputs the calculated flow rate measurement deviation rate _γest to the correction calculation unit 312. In the following equation (10), β is a volumetric flow ratio calculated by the above equation (8), and c and d are constants. The constants c and d are, for example, actually measured to obtain c and d, and calculated from the measurement results by the least square method.
γ _est = c · β + d (10)

The correction operation unit 312 corrects the mass flow rate Q input from the mass flow rate operation unit 41 using the flow rate measurement deviation rate γ _est input from the flow rate measurement deviation rate calculation unit 311. The correction operation unit 312 calculates a corrected mass flow rate _Qcom , which is a value obtained by correcting the mass flow rate Q using the flow rate measurement deviation ratio _{γest according} to the following arithmetic expression (11). The correction operation unit 312 outputs the calculated corrected mass flow rate _Qcom .
Q _com = Q / (1 + γ _est ) (11)

  As described above, in the Coriolis mass flow meter 2 according to the second embodiment, the mass input from the mass flow rate calculation unit 41 based on the amplitude of the digital signal DA corresponding to the amplitude of the detection signal SA of the upstream sensor 12 Since the flow rate Q is corrected, the mass flow rate Q can be accurately determined even if air bubbles are mixed in the fluid to be measured.

  Although the flow rate measurement deviation ratio calculation unit 311 of the correction unit 300 described above calculates the volumetric flow ratio β based on the amplitude of the digital signal DA corresponding to the amplitude of the detection signal SA of the upstream sensor 12, the downstream sensor The volumetric flow ratio β may be calculated based on the amplitude of the digital signal DB corresponding to the amplitudes of the 13 detection signals SB. In addition, although the flow rate measurement deviation rate calculation unit 311 calculates the volumetric flow rate ratio β by performing the calculation of the arithmetic expression (8), the gas-liquid ratio calculation information (gas mixture coefficient AF obtained in the first embodiment) A one-to-one correspondence relationship between A and the void ratio) may be used as the volumetric flow ratio β.

Further, although the flow rate measurement deviation ratio calculation unit 311 of the correction unit 300 described above uses the effective value A _eff of the voltage of the detection signal SA of the upstream sensor 12 in the calculation of the arithmetic expression (8), the effective value A Instead of _eff, the amplitude AmpS output from the amplitude calculation unit 111 of the estimation unit 100 or the gas mixing coefficient AF output from the gas mixing coefficient calculation unit 112 may be used. Or, based on both the amplitude of the detection signal SA of the upstream sensor 12 and the amplitude of the detection signal SB of the downstream sensor 13, for example, the gas mixing coefficient AF calculated by the above-mentioned arithmetic expression (6) is effective. It may be used instead of the value _Aeff .

FIG. 8 is a graph for explaining the relationship between the volumetric flow rate ratio β and the flow rate measurement deviation rate γ _meas . In FIG. 8, the horizontal axis is the measured value of the volumetric flow ratio β, and the vertical axis is the measured value of the flow measurement deviation ratio γ _meas . In the measurement according to FIG. 8, the line pressure to the measurement tube T is 0.2, 0.25, 0.3 [MPa], and the reference mass flow rate Q _std is 2.7, 2.4, 2.0 , 1.6, 1.2 [kg / s]. Moreover, the amount of air mixing was made into mixing the arbitrary quantity of 0-100 [NL / min]. Moreover, the signal and process value were measured for 100 [s]. As shown in FIG. 8, it can be seen that there is a fixed range of relationship between the volumetric flow ratio β and the flow measurement deviation ratio γ _meas . This indicates that the volumetric flow ratio β and the corrected mass flow Q _com are similarly related within a certain range.

  Although the Coriolis mass flowmeters 1 and 2 according to the first and second embodiments have been described above, the present invention is not limited to the embodiments described above, and can be freely changed within the scope of the present invention. .

1, 2 Coriolis mass flowmeter, T: measuring tube, 10: detection unit, 11: vibrator, 12: upstream sensor (first sensor), 13: downstream sensor (second sensor), 14: temperature Sensor 20: conversion unit 21: clock signal oscillator 22, 22, 37: track and hold (T & H) circuit 23, 28, 38: A / D converter 24, 29: LPF, 25, 30: differential Filter 26, 31 ... phase operation unit 32, 32 ... phase difference operation unit, 33 ... time delay element, 34 ... frequency operation unit, 35, 39 ... averaging circuit, 36 ... excitation circuit, 40 ... density operation unit, 41 ... Mass flow rate calculation unit 100 estimation unit 111 amplitude calculation unit 112 gas mixing coefficient calculation unit 113 gas-liquid ratio calculation unit 114 gas-liquid ratio calculation information storage unit 131 notification unit 132 threshold value Memory, 300 ... correction , 311 ... flow measurement deviation calculating unit, 312 ... correction calculation unit

Claims (4)

A Coriolis mass flowmeter that measures the mass flow rate of the fluid based on the phase difference between the output signals of first and second sensors that detect the vibration of a measurement tube through which the fluid flows.
An amplitude calculation unit for calculating at least one of the first and the amplitude is the amplitude of the first output signal of the sensor, the second amplitude is an amplitude of an output signal of said second sensor,
A gas-liquid ratio calculation unit that calculates a gas-liquid ratio of the fluid using the first amplitude or the second amplitude or an average of at least one of the first amplitude and the second amplitude as a gas mixing coefficient ;
Coriolis mass flowmeter with. It further comprises a gas-liquid ratio calculation information storage unit that stores gas-liquid ratio calculation information indicating the correspondence between the gas mixing coefficient and the gas-liquid ratio,
  The gas-liquid ratio calculation unit calculates the gas-liquid ratio of the fluid using the gas mixing coefficient and the gas-liquid ratio calculation information stored in the gas-liquid ratio calculation information storage unit.
  The Coriolis mass flowmeter according to claim 1. And a correction unit configured to correct the measured mass flow rate of the fluid based on the first amplitude or the second amplitude .
Coriolis mass flowmeter according to any one of claims 1 or 2. The information processing apparatus according to any one of claims 1 to 3, further comprising a notification unit that outputs an alarm signal according to a result of comparing the gas-liquid ratio of the fluid calculated by the gas-liquid ratio calculation unit with a predetermined threshold. Coriolis mass flowmeter as described.

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