JPS597218A - Method for measuring flow rate of fluid by flow dividing type - Google Patents

Abstract

PURPOSE:To improve the accuracy in a wide flow rate range from large to small flow rates by providing a capacity type flowmeter in a flow dividing pipeline, and providing a control valve in place of a venturi tube in a main pipeline. CONSTITUTION:The flow rate of fluid flowing in a main pipeline 3 is controlled with a control valve 6, and the distributed flow rate of the fluid flowing in a flow dividing pipeline 4 is measured with a flowmeter 5. The valve 6 is held closed while the flow rate of the flowmeter 5 maintains a prescribed value; therefore, the signal from a pulse transmitter 7 is transmitted with a control circuit 8 to an arithmetic circuit 12. The flow rate calculated by said circuit is integrated and displayed as it is on a display meter 9. When a valve 2 is further opened and the flow rate of the flowmeter 5 attains the prescribed value or above, the calculation program stored in a storage circuit 11 is fed with a control device 8 to a valve driving part 10, which opens the valve 6 by as much as said value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the flow rate of a liquid with a separate flow, particularly in a separate flow pipe. Separate flow type liquid with i ffl installed * m il
Concerning a flow rate measurement method according to the present invention.

The conventionally known pendulum pipe type flow rate δ1 has a venturi installed in the middle of the main pipe, and the flow rate passing through the hem j/-:t l no is proportional to the square root of the differential pressure before and after the benches 1 and 1. The flow m is determined by I11 using the principle of what is to be done. In other words, if the flow rate is Q and the differential pressure is Δ1, then
The flow ff1Q is determined by the above formula.

Q = CA/'ΔP C: constant of proportionality 'p of this type
! The flow rate 81 of the 2011 type 2 has the disadvantage that when the flow rate is small, the differential pressure that occurs is small, so the measurement error is large.

In addition, the pipe for differential measurement is a branch pipe, and a positive displacement flowmeter is installed at the pipe line t, 1.
It is known that the amount of liquid flowing through the venturi can be determined from the flow rate of the flow fi51, which varies depending on the differential pressure between the two. However, in the conventional technology such as hX, when the flow rate flowing in the main pipe is small, the differential pressure before and after the flow rate side becomes small, and the property of the flow passage 1 itself is changed. However, when using a small flow rate, there is a drawback that the error becomes large when the flow rate is small due to poor instrumental error. However, instead of using the flow rate measurement method described above, it is possible to directly install the flow rate 1 in the main pipe. 1 to high, and the inflow rate is 11
If 1 is used, the error when the flow rr1 old weight 1 - small flow fi1 becomes large.

The purpose of the present invention is to install a positive displacement flow meter in the branch pipe, and install a bench control valve in the main pipe, with a small volume flow meter from the inflow. Flow rate tT:
We present a novel flow measurement method that can maintain accuracy over a wide flow range.

Therefore, the present invention has a small positive displacement flow meter installed in the branch pipe branched from the main pipe, and a control system in which the opening of the melon is adjusted according to the pulses from the J positive displacement flow meter. Therefore, the control valve υ11 in the main pipe should be closed until the predetermined flow rate is reached, and the flow rate measured by the flow meter in the branch pipe should be 81. When the total flow rate reaches the predetermined flow rate or more, the control valve is opened in response to the pulse generated by the diversion 51, and the flow Ej> the outflow flowing in the diversion pipe intoxicated with tears and the outflow from the outflow. It is characterized by the diversion that flows through the control valve, which is affected by the problem, and the fact that the total flow rate is determined.
Hereinafter, examples of the present invention will be attached and further detailed with reference to the drawings.
Explain in detail.

In FIG. 1, the divided liquid flow fi31 in which the method of Hora and Akira is carried out is obtained by forming a branch pipe line 4 in a main pipe line 3 provided with a pump 1 and a valve 2. A positive displacement flow 1 it 5 is provided in 4 and a control valve 6 is provided in the main line 3 . The opening and closing of this control valve 6 is controlled by a valve driving section 10.

The positive displacement flow miller 5 is preferably of a rotary type, and is equipped with a pulse generator 7 that converts the number of revolutions into pulses.

The Takigawa pulse signal of the pulse transmitter 7 is input to the control circuit 8, and is output from the control circuit 8 to the valve interdrive @irj.
The valve drive unit 10 is driven, and the control valve 6 is controlled to open and close.

As shown in FIG. 2, the memory circuit 11 stores the total amount of the control valve 6 from the outflow (ff/m) [broken line △ violet -X-B] to the valve opening degree of the control valve 6 (jlact -C2) 1! /m) [Straight line At-A2] The formula for determining the straight line At-A2 is stored, and the performance circuit 12 calculates the current fjl(ff/) from the current h1 pulse signal from the pulse generator 7 m
＞Is this style #? ', calculates the valve opening and the total flow rate, sends a valve opening drive signal to the ↑ drive unit 10 of the control valve 6 via the control circuit 8, and sends a display signal of the total flow rate to the display S1. .

In operation, when the pump 1 is driven by a prime mover (not shown) and the valve 2 is slightly opened, the liquid tries to flow through the main pipe 3 and the branch pipe 4 in the direction of the arrow. The flowing liquid flow 11 is controlled by a control valve 6, and the distributed flow rate flowing through the branch line 4 is visually measured by a flow meter 5. The valve drive unit 10 of the control valve 6 is operated by a signal from the control circuit 8. According to the present invention, the flow rate of the flow rate cutter 5 is set to a predetermined oil, which is 20Q/m1n in the example of FIG. Up to 1), the control valve 6 is closed. Therefore, the signal from the pulse generator 7 is transmitted to the arithmetic circuit 12 via the control circuit 8, and the flow rate output from the arithmetic circuit 12'c is
The information is displayed as it is on the display total 9. Now, open the valve 2 further and the outflow from the flowmeter 5 will be at the predetermined value Wl vl'<rwa#52
off/min -L (convert, fft IIIF51 grams stored in the memory circuit 11, J<f, that is, in the example of FIG. via the control valve 6 to the valve drive unit 10.
That's the amount.

The total flow rate of the feed liquid is regulated by valve 2. Now, when valve 2 is throttled, the flow rate of flow rate 815 decreases and the number of pulses decreases. Then, the control valve 6 closes at an interval corresponding to the calculation program stored in the memory circuit 11, and the flow meter 50 is controlled to an opening degree commensurate with the flow rate. The flow rate flowing through the flowmeter 5 and the flow rate flowing through the control valve 6 are then crimped by the arithmetic circuit 12 and displayed on the display 9 as the total flow rate.

As can be seen from Fig. 2, when the total flow rate is 120 Q/min, the flow rate flowing through the flow m N15 is 40 ff/min, so the accuracy from 0 to 4 Off/min is < ff
0~120Q if you use a small Ryuginrei that can
Flow ff1j until /min! i- J1 measurement can be performed with high accuracy.

As described above, according to the present invention, the applicable flow rate range is very wide, pulsating flow is less than that of conventional volumetric flowmeters, and measurement accuracy is maintained at a high level of 1.1 J from a small flow to a maximum flow. Something will happen.

If you use the present invention, the flow rate will be 8 compared to the actual measurement type.
The durability of the lock is good because the rotation speed of 1 can be slowed down. In addition, the positive displacement flow rate N+ of the present invention is small 1 ('7 ri) small flow (0
Because of its usefulness, it is possible to measure minute flows in the culm that cannot be measured with conventional large-flow flowmeters, making it inexpensive.

[Brief explanation of the drawing]

Figure 1 shows a flow measuring device (i) for carrying out the method of the present invention.
′? 1 and 2 are graphs showing the calculation formula of the flow rate measurement method of the present invention. 1...Pump 2...Valve 33...Main pipe
4...Diversion pipe line 5...Positive flow rate δ1 6.
...Control valve 7...Pulse light, signal device

Claims (2)

[Claims] (1) A branch pipe is formed in the main pipe, a small flow meter is installed in the branch pipe, and a control valve whose opening degree is adjusted according to the flow rate signal from the flow meter is installed in the main pipe. A separate liquid flow rate measuring method characterized in that the total flow rate is measured by the flow rate flowing through the control valve derived from the flow rate of the flow meter and the flow rate on the flow rate side. (2) A patent claim characterized in that the control valve in the main pipe is closed until a predetermined flow rate is reached, and when the flow rate exceeds the predetermined flow rate, the control valve is opened in response to a flow rate signal generated by the flow ff1i+. Range 1. The split flow liquid flow rate measuring method according to item 1.