JP2002214003A - Flow meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flow meter that a measuring object is not limited. SOLUTION: A measured passage 5 is connected between a plurality of flow meters 1, 2, 3 at an upperstream side, which are placed in parallel, and a flow meter 4 at a downstream side. A flow rate flowing down in the measured passage 5 can be measured by the flow meter 1, the flow meter 2 or the flow meter 3. On the other hand, when the flow rate flowing down in the measured passage 5 is fine the flow rate can be computed and measured as a difference between flow rate values measured by the flow meter 1 and the flow meter 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow meter, and more particularly, to a flow meter capable of accurately measuring a flow rate from a small amount to a large amount.

[0002]

2. Description of the Related Art Conventionally, various types of flowmeters such as a Karman vortex flowmeter, an electromagnetic flowmeter, a positive displacement flowmeter, and a Coriolis flowmeter have been used. For example, a Karman vortex flowmeter detects the number of Karman vortices generated when a fluid passes through a vortex generator provided in a flow path, and converts the fluid flow rate or the passing flow rate.

[0003]

In the above-mentioned conventional flow meter, the size of the flow rate range that can be measured, that is, the ratio between the maximum measured flow rate and the minimum measured flow rate (hereinafter referred to as rangeability), although varying in degree. ) Is limited, and there is a problem that the measurement target of the flow rate is limited.

[0004] Further, the conventional flow meter cannot accurately measure a small flow rate, and similarly has a problem that the measurement target is limited. For example, the Karman vortex flow meter measures the flow rate using the fact that the Strouhal number is constant in a range of a predetermined Reynolds number in the flow path and the vortex frequency and the fluid flow velocity are in a proportional relationship in this range, When the flow rate decreases, the measurement becomes impossible because the Reynolds number decreases and the Strouhal number does not remain constant.

Accordingly, an object of the present invention is to provide a flow meter whose measurement range is not limited by the flow rate.

[0006]

Means for Solving the Problems The present invention, which has been made to solve the above problems, is provided in a flow path of a measurement fluid and measures a flow rate passing through the flow path. A flow meter is arranged in series, a flow path to be measured for measuring the flow rate is connected between the plurality of flow meters arranged in series, and a flow meter on the upstream side and a flow meter on the downstream side of the measured flow path Calculate the passing flow rate of the flow path to be measured from the difference between the measured flow rate and the measured flow rate. ,
Alternatively, the flow rate passing through the flow path to be measured is calculated from the sum of the measured values of a plurality of units.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A flow path to be measured is connected between a plurality of flow meters arranged in series, and the flow rate to be measured is determined from the difference between the measured values of the flow meters upstream and downstream of the flow path to be measured. By calculating the flow rate passing through the road, the flow rate passing through the flow path to be measured can be reduced by setting the flow rate passing through the upstream and downstream flow meters to a flow rate that can be measured accurately. Even small flow rates that cannot be measured by a single flow meter can be accurately calculated and measured.

[0008] One of a plurality of upstream flow meters arranged in parallel
By calculating the flow rate through the flow path to be measured from the measured values of one unit or the total of the measured values of multiple units, it measures from a relatively small flow rate of only one unit to a large total flow amount of multiple parallel units And the rangeability can be increased.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a plurality of flowmeters 1, 2, 3 on the upstream side arranged in parallel, a flowmeter 4 on the downstream side, and
A flow meter is constituted by the measured flow path 5 connected between the two. The flowmeters 1, 2, 3, and 4 can measure the flow rate independently, such as a conventionally used Karman vortex flowmeter, electromagnetic flowmeter, positive displacement flowmeter, or Coriolis flowmeter. Is fine.

A common inlet-side pipe line 6 and an outlet-side pipe line 7 are connected to the flow meters 1, 2, and 3. The pipe 7 is connected to the flow meter 4 via a valve 8, and is branched and connected to the flow path 5 to be measured. A pipe 9 is connected to the outlet side of the flow meter 4. All of the fluid flowing down from the pipe line 6 passes through the flow meter 1 or 2 or 3 and flows down to the flow path 5 to be measured, or a part of the fluid flows down to the flow path 5 to be measured and the remaining fluid It flows down to the flow meter 4.

Valves 10, 11, 12, 13, 14, and 15 for opening and closing the flow paths are respectively attached to the inlet and outlet sides of the plurality of flow meters 1, 2, and 3 arranged in parallel.
The flow meters 1, 2, 3 and the flow meter 4 are arranged in series via a pipe 7.

A fluid using device 17 is connected to the measured flow path 5 via a valve 16. In the present embodiment, the flow rate flowing into the fluid use device 17 from the measured flow path 5 is measured and calculated by the flow meters 1, 2, 3, and 4.

When the amount of fluid from the line 6 is relatively small, the valves 10, 11, and 16 are opened and the other valves are closed to reduce the flow rate passing through the flow path 5 to be measured. The measurement calculation can be performed by the total 1.

When the flow rate from the pipe 6 increases to an amount that cannot be measured by the flow meter 1 alone, the valves 12 and 13 are also opened, and the measurement is performed by two flow meters including the flow meter 2, and the flow rate is further measured. When the number increases, the flow rate is measured by three flow meters including the flow meter 3 in the same manner. Thus, by arranging a plurality of flow meters in parallel, the flow rate passing through the measured flow path 5 can be appropriately changed from a relatively small flow rate by one flow meter to a large flow rate by a plurality of flow meters. Can be measured.

Next, when a minute flow rate that cannot be measured by one flow meter 1 passes through the measured flow path 5, the minute flow rate is measured by the flow meters 1 and 4 arranged in series. That is, the pipeline 6
Is measured by the flow meter 1, the flow rate flowing down from the pipes 7 to 9 is measured by the flow meter 4, and these measured values are sent to an arithmetic unit (not shown), and the difference between the two is measured. Road 5
Is calculated and displayed or stored as the flow rate passing through.

By setting the flow rate flowing down the flow meters 1 and 4 to an amount that does not cause an error in each of the flow meters 1 and 4, the flow rates can be accurately measured by the respective flow meters 1 and 4. From the difference between the two, the minute flow rate passing through the measured flow path 5 can be accurately calculated and measured. For example, if the measured values of the two flow meters 1 and 4 are the same, the flow rate flowing down the flow path 5 to be measured is zero, and theoretically such a minimum measured flow rate can be measured from zero.

In the case where the fluid flows backward through the measured flow path 5,
That is, when the fluid passes from the fluid using device 17 to the flow path 5 to be measured, the valves 11, 13, and 15 are closed and the valve 8 is opened.
It is also possible to measure the flow rate flowing back from 7 to line 9.

[0018]

As described above, according to the present invention, even if the flow rate passing through the flow path to be measured is a very small flow rate that cannot be measured by a single flow meter, the flow rate can be measured by a single flow meter. Even a large flow rate that cannot be measured can be measured accurately. Therefore, the measurement range of the flow meter is not limited by the passing flow rate.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a flow meter according to the present invention.

[Explanation of symbols]

 1, 2, 3 Upstream flow meter 4 Downstream flow meter 5 Flow path to be measured 6 Inlet line 9 Outlet line 17 Fluid using device

Claims (1)

[Claims] 1. A method for measuring a flow rate passing through a flow path provided in a flow path of a measurement fluid, wherein a plurality of flow meters are arranged in series, and between the plurality of flow meters arranged in series. Connect the flow path to be measured to measure the flow rate, and calculate the flow rate through the flow path to be measured from the difference between the measured value of the flow meter on the upstream side and the flow meter on the downstream side of the flow path to be measured. The flowmeters on the side to be measured are calculated from one measured value of the plural flowmeters arranged in parallel, or from the total of the measured values of the plural flowmeters. Flowmeter characterized by the following.