JPH02134515A - Flow measurement - Google Patents

Abstract

PURPOSE:To make an apparatus compact by amplifying flow-rate noises obtained through a microphone, arranging the noises into frequencies in a band in use through a frequency filter, and displaying the numerical value after DC conversion. CONSTITUTION:Flow-rate noises generated between the valve of a governor and a valve sheet which are detected through a microphone are inputted into a flowmeter. At this time, the signal from the microphone 3 is amplified in an amplifier 5. The signal is arranged into a usable frequency bands through a filter 6. The signal undergoes DC conversion in a DC converter 7. The signal is corrected in a corrector 9 based on a pressure value from the pressure gage. Thereafter, the value is displayed on a display device 10. In this constitution, the apparatus can be made compact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring a fluid (gas, liquid) flowing in a flow path.

[Prior Art] There are various methods for measuring the flow rate of fluid depending on the type, flow rate, properties, etc. of the fluid. Taking city gas as an example, there are the following methods.

a. Membrane gas meter This measurement method involves putting gas into a bag (measuring chamber) of a certain capacity, filling it and then discharging it, and converting the number of times gas is filled into a unit of volume and displaying it externally.Currently, city gas Most of the gas meters installed in general consumers are of this type.

b. Full-buoy flowmeter This measurement method uses the property that a gradually expanding side wall is formed in front of the nozzle, and the fluid ejected from the nozzle adheres to this side wall and flows due to the Coanda effect. A part of the fluid flowing along the side wall is guided to a control nozzle provided on the side wall, and the fluid energy injected from this control nozzle switches the fluid to flow along the opposite side wall, and the number of switches, that is, the oscillation frequency This meter is based on the principle that it is proportional to the flow rate, and although some of this meter has been put into practical use, it lacks stability in the small flow rate range, so it is not widely used.

C4 flow rate type gas meter This measurement method involves restricting a part of the flow path, attaching a flow rate sensor to this restricted part, and converting and displaying the flow rate from the detected flow rate. This has problems such as resistance, and there are almost no examples of this being put into practical use.

d. Throttle mechanism meter Are the flowmeters a to C above used for measuring relatively small flow rates (low pressure)?This throttle mechanism meter is used for measuring relatively large flow rates (high pressure). It is used to measure the flow rate by measuring the differential pressure that occurs before and after the constriction.

[Problems with Prior Art] In the flow rate measurement methods in the four examples above, it is necessary to install a meter in the measurement flow path. Therefore, when installing a meter to existing piping, it is necessary to cut the piping each time, and during this construction period, the fluid must be stopped or
Other bypasses are being taken, and there are supply and cost issues. Further, in the case of a throttle mechanism type meter, there is a problem that pressure loss is large.

The present invention has been proposed in view of the above points, and it is possible to measure the flow rate in a supply pipe at an extremely low cost without cutting the flow path (piping), and it does not involve pressure loss. The purpose is to propose a flow measurement method.

[Means for solving the technical problem] The flow noise generated in the measurement flow path is converted into an electric signal using an acoustic transducer, and the converted electric signal is converted to a certain level using a frequency filter. A method for measuring the flow rate of a fluid flowing in a certain measurement flow path, which organizes the frequency signals into frequency bands, converts the frequency signals into DC, and displays them.

In the above measurement method, if there is a pressure fluctuation in the fluid to be measured, this pressure fluctuation may cause a measurement error, so if high accuracy is required, it is recommended to correct it using the pressure value. .

As a means of generating flow noise in the measurement flow path, it is possible to form a constriction part in the flow path, insert a dam plate, or to generate flow noise when flowing between the Harz and the valve seat. may be detected. A microphone can be used as a means for detecting this flow noise. This microphone does not need to be inserted into the flow path, and it is sufficient to closely contact the flow noise generating section from the outside.

An ordinary amplifier can be used as the acoustic transducer, and the frequency filter is required to remove the resonant frequency band from the flow noise and filter only the stable frequency band.

FIG. 5 shows the relationship between the power spectrum and frequency when flow rate noise is obtained using a Reynolds governor attached to a gas supply pipe. As is clear from this figure, the resonant frequency band of the governor is 2.3Ktlz/
It is about 5KH, /div from d iv, so 5KH
, /div to l OKtlz /div is effective as the frequency band to be used.

[Function] A microphone is attached to the outside of the flow noise generating part in the piping, and the flow noise picked up by this microphone is guided to an amplifier and amplified, and then organized into frequencies within the usage band by a frequency filter. and is displayed numerically after DC conversion.

[Example] Fig. 1 shows an example of the above-mentioned present invention.
is a gas pipe, and gas is flowing through it. Reference numeral 2 is a Reynolds governor that regulates the gas pressure supplied via the gas pipe 1.

3 is a microphone that is placed in close contact with the valve (pressure regulating Harz) of the governor 2 from the outside, and the flow noise generated between the pulp in the governor 2 and the valve seat detected by this microphone 3 is the Total of 4. The configuration of the flow meter 4 is shown in FIG. 2, in which the signal from the microphone 3 is amplified by an amplifier 5, organized into a usable frequency band by a filter 6, and converted to DC by a DC converter 7. , is corrected by a corrector 9 based on the pressure value from the pressure gauge 8 shown in FIG.

Figure 3 shows the relationship between flow rate and flow noise.

Figure 4 shows the relationship between flow rate and flowmeter output. These data were obtained from the above example, and it can be seen that the flow rate noise and flow meter output have a correlation with the flow rate.

[Effects of the Present Invention] As described above, the present invention measures the flow rate based on the flow noise generated within the flow path. As a result, we can expect the following results.

a. Flow rate noise can be acquired (heard) from outside the piping using a microphone or the like, so there is no need to cut the piping each time, and this is particularly useful for measuring large flow rate (high pressure) fluids.

b. There are already existing Reynolds governors, flow control valves, etc. as flow rate noise generating points in the piping, so by using these, there is no need to create a special flow rate noise generating point. As a result, there is no need to cut the pipe or take a bypass, and no pressure loss is caused due to flow rate measurement.

In the case of C1 city gas, the flow rate control equipment can be constructed using a governor installed in the supply piping, so the cost for constructing the flow rate management equipment can be reduced.

d1 The device for carrying out the present invention can be miniaturized. Therefore, it can be carried anywhere, making it highly adaptable to on-site construction and extremely convenient.

[Brief explanation of the drawing]

Figure 1 is an example diagram of the present invention applied to a Reynolds governor installed in a gas supply pipe, Figure 2 is a block tire diagram showing a flow meter, and Figure 3 is the relationship between flow rate and flow noise. FIG. 4 is an explanatory diagram showing the relationship between flow rate and flowmeter output, and FIG. 5 is a power spectrum diagram of flow noise. Gas piping Reynold Governor Microphone Flowmeter Amplifier Filter DC Converter Pressure Gauge Compensator Display Recorder To?
He L-2 field＼CD Sufu

Claims (2)

[Claims] 1. The flow noise generated in the measurement flow path is converted into an electrical signal using an acoustic transducer, and the converted electrical signal is organized into a certain frequency band using a frequency filter. A method for measuring the flow rate of a fluid flowing in a certain measurement channel, which converts the signal into DC and displays it. 2. 2. The flow rate measurement method according to claim 1, wherein the pressure of the fluid flowing in the measurement channel is detected, and the measured value is corrected based on the detected value.