JPH08166265A - Bidirectional flow rate measuring method and device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to measure the flow rate in both forward and reverse directions while using one differential pressure transmitter as the differential pressure measuring means. [Constitution] In a positive / negative range, a differential pressure transmitter 5 for transmitting a differential pressure between both sides of the pipe line 1 with the valve 2 as a boundary, as a differential pressure signal, and a degree of opening of the valve 2 as an opening signal. An opening transmitter 4 for transmitting, a differential pressure value calculation circuit 7 for outputting the differential pressure value calculated based on the differential pressure signal as signed differential pressure value data, and a loss coefficient value calculated based on the opening signal. Loss coefficient value calculation circuit 8 for outputting as loss coefficient value data
And a flow direction determination circuit 9 that determines the flow direction in the pipeline 1 based on the signed differential pressure value data, and the flow rate at the current opening based on the signed differential pressure value data and the loss coefficient value data. And a flow rate calculation circuit 10 for calculating

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measurement in a pipe in which a fluid flows bidirectionally, and relates to a twin backward flow rate measurement method and apparatus.

[0002]

2. Description of the Related Art Conventionally, when measuring the flow rate in a valve interposed in the middle of a pipe, the relationship between the opening of the valve and the size of the flow passage cross-sectional area at each opening is obtained in advance.
The differential pressure measuring means measures the differential pressure of the fluid in the pipe before and after the valve, and measures the flow rate based on the measured differential pressure value and the flow passage cross-sectional area corresponding to the valve opening at the time of measurement. It was

[0003]

In the above configuration, there is a differential pressure transmitter as a differential pressure measuring means.
Since the conventional differential pressure transmitter transmits an analog signal with a positive signal value according to the magnitude of the differential pressure, it supports the positive flow direction when fluid flows bidirectionally in the pipeline. It is necessary to provide the differential pressure transmitter and the differential pressure transmitter corresponding to the reverse flow direction, which is wasteful in the device configuration.

The present invention solves the above-mentioned problems.
It is an object of the present invention to provide a bidirectional flow rate measuring method and apparatus capable of measuring a flow rate in a forward / reverse bidirectional flow while using a single differential pressure transmitter as a differential pressure measuring means.

[0005]

In order to solve the above-mentioned problems, the bidirectional flow rate measuring method of the present invention uses a valve installed in the middle of a pipe in a pipe in which fluid flows bidirectionally. The differential pressure between the two sides, which is the boundary, is measured by the differential pressure transmitter, and the differential pressure signal of the signal value from the differential pressure transmitter according to the magnitude of the differential pressure is used as the signal value in the positive range during forward flow and during reverse flow. Transmits as a signal value in the negative range, receives the differential pressure signal, calculates the differential pressure value in the differential pressure value calculation circuit, and outputs the calculated differential pressure value as signed differential pressure value data to determine the valve opening. The loss coefficient corresponding to the opening is measured in the loss coefficient value calculation circuit by transmitting the opening signal of the signal value according to the opening degree measured by the opening transmitter and receiving the opening signal. While calculating the numerical value, the calculated loss coefficient value As a flow rate calculation circuit that receives the signed differential pressure value data and determines the flow direction in the pipeline in the flow direction determination circuit, and receives the signed differential pressure value data and the loss coefficient value data that have passed through the flow direction determination circuit. In the circuit, the flow rate at the current opening is calculated.

The bidirectional flow rate measuring device of the present invention has a positive and negative measuring range, is connected to a pipe line through which a valve is provided, and measures the differential pressure between both sides of the pipe line with the valve as a boundary. A differential pressure transmitter for transmitting a differential pressure signal having a signal value according to the magnitude of pressure,
An opening transmitter that connects to the valve to measure the opening of the valve and sends an opening signal with a signal value according to the opening size, and a flow rate measurement calculation connected to the differential pressure transmitter and the opening transmitter. A differential pressure value calculation circuit for calculating a differential pressure value based on the differential pressure signal and outputting the calculated differential pressure value as signed differential pressure value data; Loss coefficient value calculating circuit for calculating the loss coefficient value corresponding to the opening degree based on the degree signal, and outputting the calculated loss coefficient value as loss coefficient value data, and the pipeline based on the signed differential pressure value data. And a flow rate calculating circuit for calculating the flow rate at the current opening based on the signed differential pressure value data and the loss coefficient value data.

[0007]

With the above-described structure, the differential pressure transmitter detects the differential pressure between both sides of the pipe line, which borders the valve, regardless of the direction in which the fluid flows in the pipe line. The transmitter can measure the flow rate of the fluid flowing in both the forward and reverse directions.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of the flow rate measuring device in this embodiment. In FIG. 1, a valve 2 is provided in the middle of a pipeline 1, and the valve 2 has a characteristic that a change in flow rate with respect to a change in opening is relatively linear. An opening transmitter 4 is connected to the drive device 3 of the valve 2, and the opening transmitter 4 measures the opening of the valve 2 and outputs an opening signal (a signal having a signal value corresponding to the opening size) ( Analog signal) is transmitted. The differential pressure transmitter 5 is provided so as to be connected to both sides of the pipeline 1 with the valve 2 as a boundary, and the differential pressure transmitter 5 measures the differential pressure between both sides of the pipeline 1 to measure the magnitude of the differential pressure. A differential pressure signal having a signal value is transmitted according to the level. Differential pressure transmitter 5
Has a positive and negative full scale as a measurement range, and emits a differential pressure signal with a signal value in the positive range during a positive flow and a differential pressure signal with a signal value in the negative range during a reverse flow.

The flow rate measurement arithmetic unit 6 connected to the opening transmitter 4 and the differential pressure transmitter 5 is provided with various functional circuits formed by a program or the like. As the functional circuits, the differential pressure value arithmetic circuit 7, There are a loss coefficient value calculation circuit 8, a flow direction determination circuit 9, and a flow rate calculation circuit 10.

The differential pressure value calculation circuit 7 calculates the differential pressure value based on the differential pressure signal transmitted from the differential pressure transmitter 5.
It has a function of outputting the calculated differential pressure value as signed differential pressure value data. The loss coefficient value calculation circuit 8 has a function of calculating a loss coefficient value corresponding to the opening based on the opening signal transmitted from the opening transmitter 4 and outputting the calculated loss coefficient value as loss coefficient value data. I carry it. The flow direction determination circuit 9 has a function of determining the flow direction in the conduit 1 based on the signed differential pressure value data output from the differential pressure value calculation circuit 7. The flow rate calculation circuit 10 has a function of calculating the flow rate at the present opening degree based on the signed differential pressure value data and the loss coefficient value data, and calculates the flow velocity from the differential pressure value and the loss coefficient value in advance. The flow rate is calculated by multiplying the flow passage cross-sectional area and the flow velocity at each set opening.

The operation of the above structure will be described below. In the state where the fluid flows in the pipe line 1 in either forward or reverse direction, the pipe line 1 having the valve 2 as a boundary by the differential pressure transmitter 5
The differential pressure between the both sides of the differential pressure transmitter 5 is measured, and a differential pressure signal having a signal value corresponding to the magnitude of the differential pressure is transmitted from the differential pressure transmitter 5 to the differential pressure value calculation circuit 7. At this time, if the flow in the pipeline 1 is a positive flow, the differential pressure signal has a signal value in the positive range, and if the flow in the pipeline 1 is a reverse flow, the differential pressure signal has a signal value in the negative range. On the other hand, the opening of the valve 2 is measured by the opening transmitter 4, and the opening transmitter 4 transmits an opening signal having a signal value according to the size of the opening to the loss coefficient value calculation circuit 8.

Next, the differential pressure value calculation circuit 7 receives the differential pressure signal to calculate the differential pressure value, and outputs the calculated differential pressure value as signed differential pressure value data to the flow direction determination circuit 9 for flow. The direction determining circuit 9 receives the signed differential pressure value data and determines the flow direction in the conduit 1. On the other hand, the loss coefficient value calculation circuit 8 receives the opening signal to calculate a loss coefficient value corresponding to the opening degree, and transmits the calculated loss coefficient value to the flow rate calculation circuit 10 as loss coefficient value data. Next, the flow rate calculation circuit 10 receives the signed differential pressure value data and the loss coefficient value data input via the flow direction determination circuit 9, and calculates the flow rate at the current opening degree.

[0013]

As described above, according to the present invention, the differential pressure transmitter detects the differential pressure between the both sides of the pipeline, which borders the valve, regardless of the direction in which the fluid flows in the pipeline. Therefore, the flow rate of the fluid flowing in both the forward and reverse directions can be measured by one differential pressure transmitter.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a flow rate measuring device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Pipeline 2 Valve 4 Opening Transmitter 5 Differential Pressure Transmitter 6 Flow Rate Measurement Calculation Device 7 Differential Pressure Value Calculation Circuit 8 Loss Factor Value Calculation Circuit 9 Flow Direction Discrimination Circuit 10 Flow Calculation Circuit

Claims (2)

[Claims] 1. In a pipeline in which fluid flows in both forward and reverse directions, the differential pressure between the two sides of a valve interposed in the pipeline is measured by a differential pressure transmitter, and the differential pressure transmitter is used. A differential pressure signal with a signal value corresponding to the magnitude of the differential pressure is transmitted as a signal value in the positive range during forward flow and as a signal value in the negative range during reverse flow, and the differential pressure signal is received by the differential pressure value calculation circuit. Along with calculating the value, the calculated differential pressure value is output as signed differential pressure value data, the valve opening is measured with the opening transmitter, and the signal value from the opening transmitter according to the size of the opening. Of the opening factor signal, the loss factor value calculation circuit receives the opening amount signal to calculate the loss factor value corresponding to the opening amount, and outputs the calculated loss factor value as loss factor value data. Receive the pressure value data and place it in the pipeline in the flow direction determination circuit. The flow rate calculation circuit calculates the flow rate at the present opening degree by receiving the signed differential pressure value data and the loss coefficient value data that have passed through the flow direction determination circuit. . 2. A signal according to the magnitude of the differential pressure, which has a positive and negative measurement range, is connected to a pipeline through which a valve is interposed, and measures the differential pressure between both sides of the pipeline with the valve as a boundary. A differential pressure transmitter that transmits a differential pressure signal of a value, an opening transmitter that is connected to the valve, measures the opening of the valve, and transmits an opening signal of a signal value according to the size of the opening. A pressure transmitter and a flow rate measurement arithmetic unit connected to the opening degree transmitter are provided, and the flow rate measurement arithmetic unit calculates a differential pressure value based on the differential pressure signal, and the calculated differential pressure value is a differential pressure with a sign. A differential pressure value calculation circuit for outputting as value data, and a loss coefficient value calculation circuit for calculating a loss coefficient value corresponding to the opening based on the opening signal and outputting the calculated loss coefficient value as loss coefficient value data. And a flow direction for determining the flow direction in the pipeline based on the signed differential pressure value data A bidirectional flow rate measurement device comprising: a determination circuit; and a flow rate operation circuit that calculates a flow rate at the current opening based on the signed differential pressure value data and the loss coefficient value data.