JP7129797B2 - Turbine flow meter - Google Patents

Description

The present invention comprises a turbine rotor that is rotatably provided in a flow path through which a fluid passes and that rotates as the fluid passes; The present invention relates to a turbine type flowmeter having a flow rate integrated value derivation unit that calculates the flow rate of the fluid and derives the calculated flow rate integrated value of the fluid.

Conventionally, as a gas flow meter for measuring the flow rate of a fluid such as city gas, a turbine-type flow meter is known which measures the flow rate of a fluid by rotating a turbine rotor arranged in the flow path of the fluid. (See Patent Document 1). The turbine rotor consists of a plurality of blades arranged at a predetermined angle with respect to the flow direction of the fluid, and the flow rate of the fluid is measured from the rotation speed of the turbine rotor when the fluid passes through the turbine rotor. be. Since the conventional turbine type flowmeter can be easily increased in size, it is particularly suitable for measuring the flow rate of a fluid in a large flow range. is approximately proportional, it is possible to measure the flow rate of the fluid with practically sufficient accuracy by a simple method of converting the rotation speed of the turbine rotor into the flow rate.

JP-A-4-158222

However, if an unsteady flow accompanied by a sudden change in flow rate occurs, that is, if a sudden increase or a sudden decrease in flow rate occurs, the inertia of the turbine rotor, etc., will cause the rotation speed to not immediately correspond to the actual flow rate. However, this can result in over-metering, in particular where the measured value exceeds the actual flow rate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and its object is to provide a turbine type flowmeter capable of suppressing overmetering due to the inability of the rotation of the turbine rotor to follow the actual flow rate of the fluid to be measured. It is in.

The turbine type flowmeter for achieving the above purpose is
a turbine rotor that is rotatably provided in a main flow passage through which the fluid passes and that rotates as the fluid passes through;
Turbine type flow rate, comprising a flow rate integrated value derivation unit that calculates the flow rate of the fluid based on the detection result of the rotation speed detection unit that detects the rotation speed of the turbine rotor, and derives the calculated integrated flow rate value of the fluid. which is characterized by:
a bypass flow path that connects an upstream portion and a downstream portion of the turbine rotor in the flow direction of the fluid in the main flow path;
a flow state detection unit that detects a flow state of the fluid in the bypass channel;
and an integrated value correcting section for correcting the flow integrated value derived by the flow integrated value deriving section based on the detection result of the flow state detecting section.

According to the above characteristic configuration, apart from the main flow path, a bypass flow path connecting the upstream side portion and the downstream side portion of the turbine rotor in the flow direction of the fluid in the main flow path, and the flow of the fluid in the bypass flow path. Since it is provided with a flow state detection unit that detects the state, for example, the bypass flow path is a flow path with a flow path diameter sufficiently smaller than that of the main flow rate, and although it is not suitable for measuring a large flow rate area, it is a small flow area. By providing a flow meter or the like having a fast response speed to a change in flow rate as a flow state detection section, a rapid change in flow rate can be detected by the flow state detection section.
Then, the integrated flow rate value derivation unit corrects the integrated flow rate value of the fluid according to the detection result of the flow state detection unit, so that, for example, the actual flow rate of the fluid flowing through the main flow path suddenly fluctuates. In some cases, the flow rate at the time when the turbine rotor speed and the actual flow rate deviate from the proportional relationship in the steady state is corrected by excluding from the flow rate integrated value, etc., so that the flow rate integrated value is more in line with the actual situation. can be a value.
As a result, it is possible to realize a turbine-type flowmeter capable of suppressing over-metering due to the inability of the rotation of the turbine rotor to follow the actual flow rate of the fluid to be measured.

Further features of the turbine flowmeter are:
The flow state detection unit is a flow meter that detects the flow rate of the fluid in the bypass flow path, or a flow meter that detects the flow velocity of the fluid in the bypass flow path,
The integrated value correction unit
The flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter exceeds a judgment threshold value determined corresponding to the lower limit flow rate of the fluid in the main flow path measurable by the turbine rotor. , switching to an integration step in which the flow rate integrated value derivation unit integrates the flow rate of the fluid calculated based on the detection result of the rotation speed detection unit as the flow rate integrated value,
When the flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter is below the determination threshold value, the flow rate integrated value derivation unit calculates based on the detection result of the rotation speed detection unit The point is to switch to a non-integration process in which the flow rate of the fluid is not integrated as the flow rate integrated value.

According to the above characteristic configuration, in particular, the flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter is determined corresponding to the lower limit flow rate of the fluid in the main flow path measurable by the turbine rotor. When the flow rate calculated from the rotation speed of the turbine rotor deviates from the actual flow rate in the main flow path, the flow rate calculated from the rotation speed of the turbine rotor is integrated as a flow rate integrated value when the flow rate is below the judgment threshold. can be prohibited, the flow rate integrated value can be set to a flow rate value that is more in line with reality.

Further features of the turbine flowmeter are:
The flow state detection unit is a flow meter that detects the flow rate of the fluid in the bypass flow path, or a flow meter that detects the flow velocity of the fluid in the bypass flow path,
The flow meter and the flow velocity meter are divided into a forward flow state in which the fluid flows from the upstream portion to the downstream portion in the bypass flow channel, and a forward flow state in which the fluid flows from the downstream portion to the upstream portion in the bypass flow channel. A reverse flow state in which the fluid flows toward the side portion can be separately detected,
The integrated value correction unit
When the flow rate measured by the flow meter or the flow velocity measured by the flow rate meter is in the forward flow state, the flow rate integrated value derivation unit calculates based on the detection result of the rotation speed detection unit. integrate the flow rate of the fluid obtained as the integrated flow rate value;
When the flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter is in the reverse flow state, the flow rate of the fluid calculated based on the detection result of the rotation speed detection unit is The point is that it is not integrated as a flow rate integrated value.

As a result of examination based on various tests, the inventors of the present invention have found that the flow rate of the fluid in the main flow path is greatly reduced especially when the main flow path is closed downstream of the turbine rotor in the main flow path. In this case, the inventors have found that a reverse flow occurs in the bypass channel from the downstream side portion to the upstream side portion.
According to the above characteristic configuration, it is possible to suitably detect that the backflow is occurring, and when the backflow is occurring and the flow rate of the fluid in the main flow path is greatly reduced, the flow rate at that time is prohibited from being added to the flow rate integrated value, the flow rate integrated value can be set to a more realistic value.

In addition, the above-described determination threshold may vary depending on the pipe diameter of the main flow path, the average flow rate, etc., but according to the above characteristic configuration, a determination threshold that is relatively difficult to set due to such variations in value is set. Since the flow integrated value can be corrected even without the correction, it is possible to realize a turbine-type flow meter that can obtain a certain effect regardless of the installation location of the turbine rotor, for example.
Such a flowmeter includes a mass flowmeter consisting of a hot wire provided in the bypass channel and a pair of thermocouples provided both upstream and downstream of the hot wire, and a differential pressure at two points in the bypass channel. A differential pressure type flowmeter, an ultrasonic flowmeter, or the like, which measures the flow rate from a pressure point, can be preferably used.

Further, in the turbine type flowmeter described so far, when a flow rate equal to or lower than the lower limit flow rate of the fluid in the main flow path that can be measured by the turbine rotor flows through the main flow path, the bypass flow path Preferably, the flow rate or flow velocity of the fluid flowing through is used as the determination threshold.

Further features of the turbine flowmeter are:
The flow state detection unit is a differential pressure gauge that detects a value obtained by subtracting the pressure on the upstream side from the pressure on the downstream side in the bypass flow path,
The integrated value correction unit
When the differential pressure measured by the differential pressure gauge is a positive value, the flow rate integrated value derivation unit integrates the fluid flow rate calculated based on the detection result of the rotation speed detection unit as the flow rate integrated value,
When the differential pressure measured by the differential pressure gauge is a negative value, the flow rate integrated value derivation unit calculates the flow rate of the fluid calculated based on the detection result of the rotation speed detection unit. The point is that the flow rate integrated value is not integrated.

Also with the above-described characteristic configuration, it is possible to suitably detect that a backflow is occurring in the bypass flow path, and to suitably detect that the backflow is occurring. Since it is prohibited to integrate the current flow rate into the flow rate integrated value, the flow rate integrated value can be set to a more realistic value.
In addition, the above-described determination threshold may vary depending on the pipe diameter of the main flow path, the average flow rate, etc., but according to the above characteristic configuration, a determination threshold that is relatively difficult to set due to such variations in value is set. Since the flow integrated value can be corrected even without the correction, it is possible to realize a turbine-type flow meter that can obtain a certain effect regardless of the installation location of the turbine rotor, for example.

Further features of the turbine flowmeter are:
The diameter of the bypass channel is smaller than the diameter of the main channel.

According to the above-described characteristic configuration, a flowmeter or the like having a small measurement flow rate range but a fast response speed to sudden fluctuations in the flow rate can be suitably applied as the flow state detection unit provided in the bypass flow path. Correction of the integrated value can be performed more appropriately.
For example, the channel diameter of the bypass channel can be about 1% or more and 10% or less of the channel diameter of the main channel, and the absolute value is preferably about 4 mm or more and 10 mm or less.

Schematic configuration diagram of the turbine type flowmeter of the present invention Graph showing changes over time in the actual flow rate of the fluid and the flow rate measured by the flow meter

A turbine flowmeter 100 according to an embodiment of the present invention relates to a flowmeter capable of suppressing overmetering caused by rotation of a turbine rotor not following the actual flow rate of a fluid to be measured.
A turbine flowmeter 100 according to an embodiment will be described below with reference to FIGS.

As shown in FIG. 1, the turbine flowmeter 100 includes a turbine rotor 14 that is rotatably provided in a main flow path 17 through which a fluid (for example, city gas 13A) flows and rotates as the fluid passes through; A flow rate calculation unit C1 that calculates the flow rate of the fluid based on the detection result of a pickup device 16 (an example of a rotation speed detection unit) that detects the rotation speed of the turbine rotor 14; An integrator C2 for deriving an integrated flow rate value, and a bypass flow path connecting upstream and downstream parts of the turbine rotor 14 in the flow direction of the fluid in the main flow path 17 (in the direction indicated by arrow X in FIG. 1). 20, a mass flow meter 21 (an example of a flow state detector, a flow meter) that detects the flow rate (an example of a flow state) of the fluid in the bypass flow path 20, and a flow rate integrated value derived by the integrator C2. is corrected based on the result of detection by the mass flowmeter 21 . Note that the flow rate integrated value derived by the integrator C2 is the flow rate integrated value from the start of use of the turbine type flow meter 100 to the present, but instead of this, for example, for a predetermined period such as the last month It is good also as a flow integrated value in.

Note that the above-described flow rate calculating section C1, integrating section C2, and integrated value correcting section C3 are provided as functional units of the control device C. As shown in FIG. Further, the control device C is provided with a storage section M for storing thresholds and the like for correction by the integrated value correction section C3. The control device C is provided in such a manner that hardware such as various CPUs and memories and software cooperate with each other in order to appropriately exhibit these functions.
The flow rate calculating section C1 and the integrating section C2 function as a flow rate integrated value deriving section.

As shown in FIG. 1, the turbine flowmeter 100 has a flowmeter main body 11 having a main flow path 17 internally connected to a gas pipe (not shown) through which a fluid such as city gas 13A flows. Supports 12a and 12b are provided inside the main flow path 17 of the flow meter main body 11 to support the fixed shaft 13 of the turbine rotor 14 while allowing the flow of the fluid. 14 is rotatably provided.
A turbine rotor 14 having the fixed shaft 13 as a rotation axis has a plurality of blades 19 radially extending from the fixed shaft 13 and provided symmetrically in an axial view. A pickup device 16 is provided at a position where the plurality of blades 19 are provided in the flow direction of the fluid. Outputs a pulse signal according to the number. A pulse signal output by the pickup device 16 is transmitted to the flow rate calculation unit C1 of the control device C. As shown in FIG.

The bypass channel 20 has a channel diameter smaller than that of the main channel 17 . Specifically, the channel diameter of the bypass channel 20 can be about 1% or more and 10% or less of the channel diameter of the main channel 17, and the absolute value is preferably about 4 mm or more and 10 mm or less. can be used for By setting the flow path diameter of the bypass flow path 20 in this manner, the flow rate of the fluid flowing through the bypass flow path 20 is made substantially proportional to the flow rate of the fluid flowing through the main flow path 17. state can be Furthermore, the flow rate of the fluid flowing through the bypass flow path 20 can be made relatively small, and a meter that responds quickly to changes in the flow rate can be provided as the flow state detector.
In this embodiment, a mass flowmeter 21 is provided as a flow state detection unit, and the mass flowmeter 21 is provided with thermocouples 21b and 21c at both ends in the flow direction of the fluid to the bypass flow path 20. , and a hot wire heater 21a is provided between them, and the mass flow rate of the fluid flowing through the bypass flow path 20 is measured by measuring the temperature difference between the thermocouples 21b and 21c while the hot wire heater 21a is in operation. do. A signal corresponding to the flow rate measured by the mass flowmeter 21 is sent to the integrated value corrector C3 of the controller C. As shown in FIG.

Now, when the flow rate of the fluid flowing through the main flow passage 17 changes suddenly, the turbine rotor 14 cannot follow the sudden change in the fluid due to inertia, etc., and the flow rate of the fluid and the rotation speed of the turbine rotor 14 are proportional to each other. It may become irrelevant. In this case, the flow rate calculated by the flow rate calculating section C1 of the control device C deviates from the actual flow rate.
For example, as shown in the upper graph of FIG. 2, immediately after the actual flow rate of the fluid flowing through the main flow passage 17 (broken line in the upper graph of FIG. 2) suddenly decreases (from t1 to t3 in FIG. 2). during the period until In FIG. 2, the hatched portion indicated by K is in a state of overmetering.
On the other hand, the output of the mass flowmeter 21 provided in the bypass flow path 20 follows the fluctuation of the actual flow rate with a high response speed, as indicated by the dashed line in the lower graph of FIG.
Therefore, the turbine flowmeter 100 according to this embodiment is configured as follows in order to suppress the over-metering.

The control device C is provided with an integrated value correction section C3 that corrects the flow rate integrated value calculated by the flow rate computation section C1 and integrated by the integration section C2.
When the flow rate measured by the mass flowmeter 21 exceeds a judgment threshold determined corresponding to the lower limit flow rate of the fluid in the main flow path 17 measurable by the turbine rotor 14 , the value calculated by the flow rate calculation unit C1 is switched to the integration step in which the value calculated by the flow rate calculation unit C1 is integrated as the flow rate integrated value by the integration unit C2, and when the flow rate measured by the mass flow meter 21 is less than the determination threshold value, the flow rate calculation unit C1 Switching to a non-integration process in which the calculated value is not integrated as the flow rate integrated value in the integration unit C2.
As the determination threshold value, the flow rate of the fluid flowing through the bypass flow path 20 when the lower limit flow rate is flowing through the main flow path 17 can be preferably adopted.

In this embodiment, the determination threshold value is set with hysteresis in order to prevent hunting, and an additional explanation will be given below with reference to the lower graph of FIG. The lower graph of FIG. 2 shows the output of the mass flowmeter 21 with a one-dot chain line when the actual flow rate is indicated by the dashed line in the upper graph of FIG.
As shown in FIG. 2, when the above-described lower limit flow rate of the turbine rotor 14 flows through the main flow path 17, the flow rate of the fluid flowing through the bypass flow path 20 (in FIG. A value obtained by subtracting a predetermined hysteresis width from the value obtained by subtracting a predetermined hysteresis width from the value is set as a determination threshold for decrease (α1 in FIG. 2), and a value obtained by adding a predetermined hysteresis width is set as a determination threshold for increase (α2 in FIG. 2). do.
When using the determination threshold value for decrease and the determination threshold value for increase, the integrated value correction unit C3 calculates the value calculated by the flow rate calculation unit C1 when the flow rate measured by the mass flowmeter 21 exceeds the determination threshold value for increase is integrated as a flow rate integrated value in the integrator C2, and when the flow rate measured by the mass flow meter 21 falls below the threshold value for determining the decrease, the value calculated by the flow rate calculator C1 is added to the integrator C2 Switch to the non-integrated process that is not integrated as the flow rate integrated value with .
In FIG. 2, the period from t2 to t4 corresponds to the integrated value correction period during which the non-integrating process is performed.
Note that the determination thresholds described so far are pre-stored in the storage unit M, and the integrated value correction unit C3 calls these determination thresholds from the storage unit M as necessary, and restores the integrated value. Perform correction.

In the turbine flowmeter 100 according to the embodiment, in the control device C, the flow rate calculation unit C1 calculates the flow rate of the fluid based on the rotation speed of the turbine rotor 14 measured by the pickup device 16, and the calculated flow rate is calculated. The integrating unit C2 integrates the flow rate to derive the integrated flow rate value. However, with regard to the integration, the integrated value correcting section C3 stores the corrected flow rate integrated value in the storage section M in a form that prohibits integration in the non-integrating process, as described above.
The display section S displays the integrated flow rate value stored in the storage section M. FIG.

[Another embodiment]
(1) In the above embodiment, a mass flowmeter is employed as the flowmeter as the flow state detector.
As the flow meter, a differential pressure type flow meter that measures the flow rate from the differential pressure at two points in the bypass flow path 20, and a Karman flow meter that is generated when the flow of the fluid is disturbed by an obstacle provided in the bypass flow path 20 is used. A vortex flowmeter, an ultrasonic flowmeter, or the like, which measures the flow rate by measuring vortices, can be preferably used.

(2) As a result of studies based on various tests, the inventors of the present invention have found that the main flow path 17 is It has been found that when the flow rate of the fluid at 1 is greatly reduced, reverse flow occurs in the bypass channel 20 from the downstream side portion to the upstream side portion.
Therefore, in the above embodiment, the integrated value correction section C3 may be configured as follows.

First, as a flow meter, there is a forward flow state in which the fluid flows from the upstream portion to the downstream portion in the bypass flow path 20, and a flow state in which the fluid flows from the downstream portion to the upstream portion in the bypass flow path 20. A device capable of separately detecting the state of reverse current flow is adopted.
Then, when the flow rate measured by the flow meter is in the forward flow state, the integrated value correction unit C3 integrates the flow rate of the fluid calculated by the flow rate calculation unit C1 as a flow rate integrated value by the integration unit C2. However, when the flow rate measured by the flow meter is in a reverse flow state, the flow rate of the fluid calculated by the flow rate calculation unit C1 is not integrated as the flow rate integrated value by the integration unit C2. correct.
As a result, over-metering by the turbine flowmeter 100 can be prevented without setting a separate threshold value.
As the flowmeter in the second embodiment, a mass flowmeter, a differential pressure flowmeter, an ultrasonic flowmeter, or the like can be suitably used.

(3) In the above embodiment and another embodiment (2), even if the flow meter is a flow meter that measures the flow velocity (an example of the flow state) of the bypass channel 20, the effect is exhibited satisfactorily. be able to.
Note that the specific control contents are substantially the same except that the flow rate is changed to the flow velocity, so the detailed contents are omitted here.

(4) In the above embodiment, the flow state detection unit may be a differential pressure gauge that detects a value obtained by subtracting the downstream pressure from the upstream pressure in the bypass channel 20 (an example of the flow state). do not have.
In this case, when the differential pressure measured by the differential pressure gauge is a positive value, the integrated value correction unit C3 integrates the fluid flow rate calculated by the flow rate calculation unit C1 as a flow rate integrated value by the integration unit C2. When the differential pressure measured by the differential pressure gauge is a negative value, the fluid flow rate calculated by the flow rate calculator C1 is used as the flow rate integrated value by the integrator C2, and the flow rate integrated value is corrected in an integrated manner.
According to this configuration, over-metering by the turbine flowmeter 100 can be prevented without separately setting a threshold value.

It should be noted that the configurations disclosed in the above embodiments (including other embodiments, the same shall apply hereinafter) can be applied in combination with configurations disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in this specification are exemplifications, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention.

INDUSTRIAL APPLICABILITY The turbine flowmeter of the present invention can be effectively used as a turbine flowmeter capable of suppressing over-metering due to the inability of the rotation of the turbine rotor to follow the actual flow rate of the fluid to be measured.

14: Turbine rotor 16: Pick-up device 17: Main flow path 20: Bypass flow path 21: Flow meter C1: Flow rate calculating unit C2: Integrating unit C3: Integrated value correcting unit S: Display unit M: Storage unit 100: Turbine type flow meter

Claims (6)

a turbine rotor that is rotatably provided in a main flow passage through which the fluid passes and that rotates as the fluid passes through;
Turbine type flow rate, comprising a flow rate integrated value derivation unit that calculates the flow rate of the fluid based on the detection result of the rotation speed detection unit that detects the rotation speed of the turbine rotor, and derives the calculated integrated flow rate value of the fluid. and
a bypass flow path that connects an upstream portion and a downstream portion of the turbine rotor in the flow direction of the fluid in the main flow path;
a flow state detection unit that detects a flow state of the fluid in the bypass channel;
A turbine type flowmeter, comprising: an integrated value correcting section that corrects the integrated flow rate value derived by the integrated flow rate deriving section based on the detection result of the flow state detecting section. The flow state detection unit is a flow meter that detects the flow rate of the fluid in the bypass flow path, or a flow meter that detects the flow velocity of the fluid in the bypass flow path,
The integrated value correction unit
The flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter exceeds a judgment threshold value determined corresponding to the lower limit flow rate of the fluid in the main flow path measurable by the turbine rotor. , switching to an integration step in which the flow rate integrated value derivation unit integrates the flow rate of the fluid calculated based on the detection result of the rotation speed detection unit as the flow rate integrated value,
When the flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter is below the determination threshold value, the flow rate integrated value derivation unit calculates based on the detection result of the rotation speed detection unit 2. The turbine type flowmeter according to claim 1, wherein the flow rate of the fluid is switched to a non-integration process in which the flow rate integrated value is not integrated. The flow state detection unit is a flow meter that detects the flow rate of the fluid in the bypass flow path, or a flow meter that detects the flow velocity of the fluid in the bypass flow path,
The flow meter and the flow velocity meter are divided into a forward flow state in which the fluid flows from the upstream portion to the downstream portion in the bypass flow channel, and a forward flow state in which the fluid flows from the downstream portion to the upstream portion in the bypass flow channel. A reverse flow state in which the fluid flows toward the side portion can be separately detected,
The integrated value correction unit
When the flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter is in the forward flow state, the flow rate integrated value derivation unit calculates based on the detection result of the rotation speed detection unit integrate the flow rate of the fluid obtained as the integrated flow rate value;
When the flow rate measured by the flow meter or the flow velocity measured by the flow velocity meter is in the reverse flow state, the flow rate of the fluid calculated based on the detection result of the rotation speed detection unit is 2. The turbine type flowmeter according to claim 1, wherein the flow rate integrated value is not integrated. A flow rate or a flow velocity of the fluid flowing through the bypass flow path when the fluid flows in the main flow path at a measurable lower limit flow rate or less in the turbine rotor is set as the determination threshold. Item 3. The turbine type flowmeter according to item 2. The flow state detection unit is a differential pressure gauge that detects a value obtained by subtracting the pressure on the upstream side from the pressure on the downstream side in the bypass flow path,
The integrated value correction unit
When the differential pressure measured by the differential pressure gauge is a positive value, the flow rate integrated value derivation unit integrates the fluid flow rate calculated based on the detection result of the rotation speed detection unit as the flow rate integrated value,
When the differential pressure measured by the differential pressure gauge is a negative value, the flow rate integrated value derivation unit calculates the flow rate of the fluid calculated based on the detection result of the rotation speed detection unit. 2. The turbine type flowmeter according to claim 1, wherein the flow rate integrated value is not integrated. The turbine type flowmeter according to any one of claims 1 to 5, wherein the bypass flow path has a flow path diameter smaller than that of the main flow path.

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