JP5822302B2 - Gas meter characteristic evaluation test apparatus and characteristic evaluation test method - Google Patents

Description

  The present invention relates to a characteristic evaluation test apparatus and a characteristic evaluation test method for gas measuring instruments such as a gas meter for measuring consumption of city gas and propane gas, and various flow meters used in plants and the like.

  Many gases such as air and gas exist in the immediate vicinity, and are widely used in general life and industrial fields. Gas pipes are used in gas supply lines in general life and plants in industrial fields, etc. Gas metering such as gas meters and various flow meters to manage or control the flow rate of gas flowing through these gas pipes A vessel is being used. Currently, the characteristics of the flowmeter are sufficiently evaluated for steady flow, and there are international standards and JIS standards (for example, see Non-Patent Document 1).

  However, in actual use of the fluid, the gas flow is not necessarily a steady flow, and measurement is performed in an unsteady flow having pulsation. The characteristics of the flow meter in the pulsation field may be different from the characteristics of the flow meter in the stationary field. Therefore, conventionally, in order to measure pulsation, it is necessary to go to the site where the pulsation occurs or to reproduce it with the exact same pipeline, and in order to conduct a flowmeter characteristic test in the laboratory Development of a compact pulsation reproduction test apparatus is demanded (for example, see Non-Patent Document 2). Further, as a prior art related to a flow meter in a pulsation field, there is a resonance tube method (for example, see Non-Patent Document 3). Furthermore, the development of a dynamic characteristic test apparatus for a gas flowmeter in a pressure pulsation field using a gas pressure control technique has been proposed (for example, see Non-Patent Document 4).

“Flow rate display method by ISO”, [online], SMC Corporation, [October 20, 2011 search], Internet <URL: http://www.smcworld.com/2002/md1/yougo4/yougo4. html> Tatsuya Kashiwagi, “Measurement of Gas Flow and Pulsation”, Flow Club Lecture, December 14, 2007, [October 20, 2011 Search], Internet <URL: http://www.nmij.jp/ ~ nmijclub / flowm / docimgs / funaki_20071214.pdf> Masabo Serizawa, "Vibration flow of thermoacoustic sound wave generator-Flow near the resonance tube outlet-, Cryogenic engineering, Vol. 43, No. 12, pp. 527-535 (2008) Tsuji, Jun Akihisa, Yuuki Kato, Kengo Kawashima, Toshiharu Kagawa, “Development of dynamic characteristics test equipment for gas flowmeters in pressure pulsation field”, Industrial Papers of the Society of Instrument and Control Engineers, Vol. 10, No. 1, pp. 1-6 (2011)

  In the above resonance tube system, it is necessary to change the length of the pipe line depending on the frequency of the pulsation to be generated, and it is difficult to create a pulsation field in which a plurality of frequencies are superimposed, and there is a problem that the apparatus becomes large. Further, the dynamic characteristic test apparatus for a gas flow meter in a pressure pulsation field has a problem that it can be applied only to a flow meter having a large internal resistance, such as a differential pressure type laminar flow meter, and has low versatility.

  Therefore, in the present invention, the characteristic evaluation test apparatus and characteristic evaluation test for a gas meter capable of reproducing the pulsation of an arbitrary waveform with a small device and performing the characteristic evaluation test of various gas flow meters. It aims to provide a method.

  The gas meter characteristic evaluation test apparatus of the present invention has a pipe line having one end connected to the downstream side of the gas meter and the other end closed, and an arbitrary pressure waveform to the upstream side of the gas meter. And a pressure control device for supplying gas. In addition, the gas meter characteristic evaluation test method of the present invention is configured such that the other end of the pipe line whose one end is closed is connected to the downstream side of the gas meter, and an arbitrary pressure waveform is connected to the upstream side of the gas meter. The gas is supplied by a pressure control device.

  According to these inventions, since the pipe line connected to the downstream side of the gas meter is closed, the reflection according to the volume and shape of the pipe line with respect to an arbitrary pressure waveform supplied by the pressure control device. A wave is generated. This makes it possible to perform a characteristic evaluation test including the influence of the reflected wave when an arbitrary pressure waveform is supplied to the gas meter.

  Here, the pipeline mimics the volume and shape of the pipeline where the gas meter is installed, and the pressure control device reproduces the pressure waveform of the pipeline where the gas meter is installed If it is, it will become possible to perform the characteristic evaluation test including the influence of the reflected wave in the actual pipe line in which the gas meter is installed.

  Further, the pressure control device controls a gas having an arbitrary pressure waveform by exhausting a part of the gas supplied from the gas supply source, and includes a vacuum pump for exhausting a part of the gas. It is desirable to be a thing. Thus, by controlling a gas having an arbitrary pressure waveform by exhausting a part of the gas supplied from the gas supply source by the pressure control device, the vacuum pump forcibly exhausts a part of the gas. It is possible to balance the gas supply and the exhaust and easily control the gas to have an arbitrary pressure waveform.

(1) By connecting the other end of the pipe line whose one end is closed to the downstream side of the gas meter and supplying a gas having an arbitrary pressure waveform to the upstream side of the gas meter by the pressure control device, A reflected wave corresponding to the volume and shape of the pipe line is generated for an arbitrary pressure waveform supplied by the control device, and the influence of the reflected wave when an arbitrary pressure waveform is supplied to the gas meter is included. It becomes possible to perform a characteristic evaluation test. This eliminates the need for a large device such as a resonance tube system, and allows the pulsation of an arbitrary waveform to be reproduced by a small device and to perform characteristic evaluation tests of various gas flow meters.

(2) The pipeline mimics the volume and shape of the pipeline where the gas meter is installed, and the pressure control device reproduces the pressure waveform of the pipeline where the gas meter is installed As a result, it is possible to perform a characteristic evaluation test including the influence of the reflected wave in the actual pipeline where the gas measuring instrument is installed.

(3) The pressure control device controls a gas having an arbitrary pressure waveform by exhausting a part of the gas supplied from the gas supply source, and includes a vacuum pump for exhausting a part of the gas. Since it is possible to balance the supply and exhaust of gas and easily control to a gas with an arbitrary pressure waveform, reproduce the pulsation of an arbitrary waveform with more reproducibility, It becomes possible to conduct a characteristic evaluation test of various gas flowmeters.

It is a schematic diagram of the characteristic evaluation test device in an embodiment of the present invention. It is a figure which shows the specific structure of the characteristic evaluation test apparatus of FIG. It is a block diagram which shows the control system of the pressure control apparatus in this embodiment. Is a diagram illustrating the measurement values P of the target value P _ref and the pressure sensor of the pressure in the outlet of the isothermal pressure vessel in the property evaluation test apparatus of Example 1 in a graph. Is a diagram illustrating the measurement values P of the target value P _ref and the pressure sensor of the pressure in the outlet of the isothermal pressure vessel in the property evaluation test apparatus of Example 2 in the graph.

FIG. 1 is a schematic diagram of a characteristic evaluation test apparatus according to an embodiment of the present invention.
As shown in FIG. 1, a characteristic evaluation test apparatus 1 according to an embodiment of the present invention is a test apparatus that evaluates characteristics of a gas meter G as a gas measuring instrument, and a pressure control device 2 is disposed upstream of the gas meter G. Are connected, and the pipe line 3 is connected to the downstream side of the gas meter G. Air as a test gas is supplied from the gas supply source 4 to the pressure control device 2.

  The pressure control device 2 supplies the gas supplied from the gas supply source 4 to the gas meter G as a gas having a pressure waveform such as an arbitrary amplitude, pressure, frequency or superposition wave. The pipe line 3 imitates the volume and shape of a pipe line (for example, a pipe line in a house in a gas supply system to a general household) where the gas meter G is installed, and one end is connected to the gas meter G and the other. The end is closed.

  The gas supply source 4 is a supply source that supplies compressed air, and a cylinder filled with high-pressure air can be used. Moreover, you may make it supply compressed air using pumps, such as a compressor.

FIG. 2 is a diagram showing a specific configuration of the characteristic evaluation test apparatus of FIG.
As shown in FIG. 2, the pressure control device 2 includes a servo valve 10, an isothermal pressure vessel 11, a pressure sensor 12, a computer 13 as pressure control means, and a D / A (digital / analog) converter 14. And an A / D (analog / digital) converter 15 and a vacuum pump 16.

  The servo valve 10 is a flow rate control type servo valve that regulates the flow rate of air supplied from the gas supply source 4 into the isothermal pressure vessel 11. Further, the servo valve 10 regulates the outflow rate (negative inflow rate) of air that flows backward from the isothermal pressure vessel 11. As the servo valve 10, it is preferable to use a spool type servo valve with little pressure loss.

  The servo valve 10 is a three-way valve provided with at least an intake port 10a, an exhaust port 10b, and a control port 10c. The intake port 10a is connected to the gas supply source 4 through a conduit 20a. The exhaust port 10b is connected to the vacuum pump 16 through a conduit 20b. The control port 10c is connected to the isothermal pressure vessel 11 through a conduit 20c. In the servo valve 10, the connection and opening degree between the control port 10 c and the intake port 10 a or the exhaust port 10 b are operated by a control signal output from the computer 13 via the D / A converter 14.

  The isothermal pressure vessel 11 keeps the air flowing in from the inflow port 11a through the conduit 20c in an isothermal state, flows out the air from the outflow port 11b, and supplies it to the gas meter G. The outlet 11b of the isothermal pressure vessel 11 and the inlet Ga of the gas meter G are connected by a conduit 20d. The outlet Gb of the gas meter G and the pipe line 3 are connected by a conduit 20e. The cross-sectional areas of the conduits 20a to 20e are preferably four times or more the effective cross-sectional area of the servo valve 10. This is because when the cross-sectional areas of the conduits 20a to 20e are within this range, the pressure drop caused by the conduits 20a to 20e can be almost ignored.

  As the shape of the isothermal pressure vessel 11, various shapes such as a cylindrical shape, a polygonal column, a sphere, and an ellipsoid can be adopted. For example, in the case of a cylindrical shape, air is introduced from an inflow port 11a provided on one of the bottom surfaces, and air is output from an outflow port 11b provided on the other bottom surface. The gas meter G is connected to the outlet 11b of the isothermal pressure vessel 11 via a conduit 20d. At this time, it is preferable that the depth in the air inflow direction (the height of the cylinder) is not more than twice the maximum width of the cross section (the diameter of the bottom surface). When the height (depth) of the cylinder is within this range, it is possible to suppress the generation of a pressure gradient when air flows in. In the case of a polygonal column shape, the maximum width in the cross section, and in the case of an ellipsoid, the diameter in the cross section at the center in the depth direction.

Since the isothermal pressure vessel 11 has a role of a buffer tank, the internal volume V thereof is 5.0 × 10 ⁻⁶ Q _{out to} 7.0 with respect to the air volume outflow rate Q _out [NL / min]. Although it is preferably in the range of × 10 ⁻⁵ Q _out [m ³ ], it can be appropriately determined according to the response specification of the pressure control device 2.

  The isothermal pressure vessel 11 is usually made of metal. The inside of the isothermal pressure vessel 11 is filled with a heat conductive material having a large surface area made of a fine metal wire condensate or a porous metal body. By filling the inside of the isothermal pressure vessel 11 with this heat conductive material, the heat transfer area in the inside can be increased. The heat conductive material suppresses changes in the temperature of the air in the isothermal pressure vessel 11 when the air flows into the isothermal pressure vessel 11 and the air flows out of the isothermal pressure vessel 11. And suppression of the temperature change by this heat conductive material is further effective if the isothermal pressure vessel 11 is also made high in heat conductivity.

As the heat conductive material having a large surface area, for example, a converging body of fine metal wires such as steel wool, a porous metal body such as copper wire, or a cotton-like body made of cotton or plastic can be employed. That is, in the case of a fiber-like form such as a bundle of fine metal wires or cotton or plastic cotton, the one having a fiber diameter in the range of 10 to 50 [μm] can increase the heat transfer area. preferable. Moreover, it is preferable that this heat conductive material is 0.05 [W / mK] or more in thermal conductivity. The material of the heat conductive material and the filling amount of the isothermal pressure vessel 11 are adjusted so that the temperature change of the air held in the isothermal pressure vessel 11 can be suppressed to about 3 [K]. Thus, the heat transfer area of the isothermal pressure vessel 11 can be increased by filling the isothermal pressure vessel 11 with a heat conductive material such as steel wool. Moreover, it is preferable that the packing density of a heat conductive material exists in the range of 200-400 [kg / m < ³ >]. When the filling density is within this range, the temperature change of the air in the isothermal pressure vessel 11 can be sufficiently suppressed.

  The pressure sensor 12 is connected to the outlet 11 b of the isothermal pressure vessel 11. The pressure sensor 12 measures the pressure P of air in the isothermal pressure vessel 11 and transmits a detection signal related to the measurement result (pressure value) to the computer 13 via the A / D converter 15. The pressure sensor 12 is not particularly limited as long as it can output the pressure value of air as an electrical signal. For example, a semiconductor pressure sensor or the like can be used. The measurable range of the pressure sensor 12 preferably covers the range from the atmospheric pressure to the supply pressure Ps of air supplied from the gas supply source 4.

The computer 13 detects the detection signal regarding the outflow flow rate G _out of the air from the outlet 11 b of the isothermal pressure vessel 11 measured by the gas meter G, and the pressure P of the air in the isothermal pressure vessel 11 measured by the pressure sensor 12. The detection signal is received as a digital signal via the A / D converter 15 and the inflow flow rate G _in ( _{in) of the} air flowing into the isothermal pressure vessel 11 via the servo valve 10 based on these detection signals. The control voltage E _i for controlling the “negative inflow rate” in which air flows out from the exhaust port 10 c of the servo valve 10 is transmitted to the servo valve 10 via the D / A converter 14. is there. In this computer 13, the outflow flow rate G _out of the air from the outlet 11 b of the isothermal pressure vessel 11 measured by the gas meter G and the pressure P of the air in the isothermal pressure vessel 11 measured by the pressure sensor 12. The calculation for controlling the opening / closing or opening degree of the servo valve 10 is performed as appropriate.

  The D / A converter 14 converts a digital signal related to opening / closing or opening of the servo valve 10 from the computer 13 into an analog signal and outputs the analog signal to the servo valve 10. The A / D converter 15 converts analog signals from the pressure sensor 12 and the gas meter G into digital signals and outputs them to the computer 13.

  Next, with reference to FIG. 3, the control of the pressure by the pressure control device 2 in the present embodiment will be described. FIG. 3 is a block diagram showing a control system of the pressure control device 2 in the present embodiment.

The main symbols used in the description of this embodiment are as follows.
P _ref : pressure target value [Pa]
K _p : proportional gain [(kg / s) / Pa]
K _GI : Integration gain [V / kg]
K _v : Flow rate gain of servo valve 10 [(kg / s) / V]
G _in : Inflow flow rate [kg / s]
G _out : Outflow flow rate [kg / s]
R: Gas constant [J / (kg · K)]
θ: Gas temperature [K]
V: Volume of isothermal pressure vessel 11 [m ³ ]
P: Pressure in the isothermal pressure vessel 11 [Pa]

As shown in FIG. 3, the control system of the pressure control device 2 of the present embodiment feeds back the pressure P of the air in the isothermal pressure vessel 11 to the pressure target value P _ref to perform P (proportional) operation and I The pressure control system 30 that performs PI control by (integration) operation is configured as a main loop. Moreover, the pressure differential value of the air in the isothermal pressure vessel 11 is located inside the main loop.
The model follow-up control system 31 that performs I control by I (integration) operation is configured as one minor loop.

In the pressure control system 30, the pressure P that is a control amount is fed back, and a deviation from the target value _Pref is calculated at the addition junction 32. Here, the pressure P is measured by the pressure sensor 12. The calculated pressure deviation is transmitted to the proportional element 33, the P operation is performed with the proportional gain K _p, and the I operation is performed by the integrator 34. In the pressure control system 30, PID (proportional operation, integral operation, differential operation) control may be performed instead of PI control.

In the model following control system 31, the pressure differential value of the air in the isothermal pressure vessel 11
Is multiplied by V / (Rθ) by the control element 311 to obtain an estimated value of the flow rate change and fed back to the addition junction 312. Further, the deviation calculated at the addition junction 312 is subjected to an I operation with an integral gain of K _GI by the integrator 313 and multiplied by the flow rate gain K _v of the servo valve 10 so that the flow of the isothermal pressure vessel 11 flows. inflow rate G _in flowing from the inlet 11a is calculated.

Further, with respect to the inflow rate G _in flowing from the inlet port 11a, via a conduit 20d to the gas meter G is connected, outflow rate G _out flowing out from the outlet 11b is added as a disturbance by the summing junction 315, the control Element 316 multiplies (Rθ) / V.

The calculation of the pressure control system 30 of the pressure control device 2 described above is performed by the computer 13, and the control voltage E _i calculated by the computer 13 is transmitted to the servo valve 10 via the D / A converter 14. Thus, the air in the isothermal pressure vessel 11 can be controlled to a pressure waveform such as an arbitrary amplitude, pressure, frequency, and superposed wave. The calculation of the pressure control system 30 may be performed using a general-purpose computer such as a PC (Personal Computer), or may be performed by configuring a dedicated calculation circuit.

  In this pressure control device 2, proportional feedback control is performed by a pressure control system 30 (main loop), and integral feedback control using a differential value is performed by a model following control system 31 (minor loop). Within the (minor loop), the differential value of the pressure is fed back as an estimated value of the flow rate change, so that the flow rate that has flowed out due to the disturbance is immediately compensated. Since the model following control system 31 (minor loop) is sufficiently fast with respect to the pressure control system 30 (main loop), it is possible to perform very fast compensation for the disturbance included in the model following control system 31. In addition, about the pressure differential value, when the resolution of the pressure sensor 12 is sufficiently high, it is possible to use the pressure differential value as a pressure differential value by performing primary differentiation on the pressure value measured by the pressure sensor 12 without using the pressure differential meter. However, it is also possible to use a pressure differential value measured using a pressure differential meter.

  And in the characteristic evaluation test apparatus 1 in this embodiment, the other end of the pipe line 3 whose one end is closed is connected to the downstream side of the gas meter G, and the pressure control device 2 is connected to the upstream side of the gas meter G. The controller 2 controls the air in the isothermal pressure vessel 11 to a pressure waveform such as an arbitrary amplitude, pressure, frequency, and superposed wave, and supplies the pressure waveform to the gas meter G. At this time, since the pipe line 3 connected to the downstream side of the gas meter G is closed, a reflected wave corresponding to the volume and shape of the pipe line 3 is generated with respect to an arbitrary pressure waveform supplied by the pressure control device 2. To do.

  Thereby, in the characteristic evaluation test apparatus 1 in this embodiment, the characteristic evaluation test including the influence of the reflected wave when an arbitrary pressure waveform is supplied to the gas meter G can be performed. Therefore, the characteristic evaluation test apparatus 1 in the present embodiment does not require a large apparatus such as a resonance tube system, and reproduces pulsations of an arbitrary waveform by the small pressure control apparatus 2, so that various gas flowmeters can be used. It is possible to conduct a characteristic evaluation test.

  In the characteristic evaluation test apparatus 1 according to the present embodiment, the pipe 3 is assumed to mimic the volume and shape of the pipe where the gas meter G is installed, and the pressure controller 2 is used as the pressure of the pipe where the gas meter G is installed. By reproducing the waveform, it is possible to perform a characteristic evaluation test including the influence of the reflected wave in the actual pipeline where the gas meter G is installed.

  Moreover, in the pressure control apparatus 2 in this embodiment, when controlling to the gas of arbitrary pressure waveforms by exhausting a part of gas supplied from the gas supply source 4, the vacuum pump 16 connected to the exhaust port 10b. Since a part of the gas is exhausted, the supply of gas and the exhaust gas are balanced, and it is possible to easily control the gas to have an arbitrary pressure waveform. Therefore, it is possible to perform the characteristic evaluation test of the gas meter G by reproducing the pulsation of an arbitrary waveform with higher reproducibility.

In Example 1, gas pulsation generated in an embedded gas piping system for supplying gas to a general household was measured, and the pressure fluctuation was reproduced by the characteristic evaluation test apparatus 1. Note that compressed air of 50 [kPa] was supplied from the gas supply source 4 and suctioned from the vacuum pump 16 at −50 [kPa]. The values of each parameter are as follows: K _p = 3.09 × 10 ⁶ [(kg / s) / Pa], K _GI = 3.6 × 10 ⁵ [V / kg], R = 287.03 [J / (Kg · K)], θ = 293 [K], and V = 0.026 [m ³ ].

FIG. 4 is a graph showing the target value P _ref of the pressure at the outlet 11 b of the isothermal pressure vessel 11 and the measured value P of the pressure sensor 12 in the characteristic evaluation test apparatus 1. As can be seen from FIG. 4, the characteristic evaluation test apparatus 1 can reproduce the pressure fluctuation with high responsiveness, and the characteristic evaluation test apparatus 1 can perform the characteristic evaluation test of the gas meter with high accuracy.

In Example 2, pulsation was generated in a piping system having a branch, and the pressure fluctuation was reproduced by the characteristic evaluation test apparatus 1. The values of the parameters are the same as those in the first embodiment. FIG. 5 is a graph showing the target value P _ref of the pressure at the outlet 11 b of the isothermal pressure vessel 11 and the measured value P of the pressure sensor 12 in the characteristic evaluation test apparatus 1. As can be seen from FIG. 5, the characteristic evaluation test apparatus 1 can reproduce the pressure fluctuation with high responsiveness, and the characteristic evaluation test apparatus 1 can perform the characteristic evaluation test of the gas meter with high accuracy.

  The gas meter characteristic evaluation test apparatus and the characteristic evaluation test method of the present invention are characterized by gas meter for measuring consumption of city gas and propane gas, and characteristic evaluation of gas meter such as various flow meters used in plants, etc. It is useful as an apparatus and method for conducting tests.

G Gas meter 1 Characteristic evaluation test device 2 Pressure control device 3 Pipe line 4 Gas supply source 10 Servo valve 11 Isothermal pressure vessel 12 Pressure sensor 13 Computer 14 D / A converter 15 A / D converter 16 Vacuum pump

Claims (5)

A pipe line having one end connected to the downstream side of the gas meter and the other end closed;
A gas meter characteristic evaluation test device including a pressure control device that supplies a gas having an arbitrary pressure waveform to the upstream side of the gas meter. The pipe mimics the volume and shape of the pipe where the gas meter is installed, and the pressure control device reproduces the pressure waveform of the pipe where the gas meter is installed. The apparatus for evaluating characteristics of a gas meter according to claim 1.   The pressure control device controls a gas having an arbitrary pressure waveform by exhausting a part of the gas supplied from a gas supply source, and includes a vacuum pump for exhausting a part of the gas. The apparatus for evaluating the characteristics of a gas meter according to claim 1 or 2. The pressure control device includes:
A servo valve that regulates the inflow flow rate of gas supplied from the gas supply source;
An isothermal pressure vessel that holds the gas flowing in through the servo valve in an isothermal state;
A pressure sensor for detecting the pressure of the gas in the isothermal pressure vessel;
Pressure control means for controlling the gas in the isothermal pressure vessel to a predetermined pressure by operating the servo valve;
The gas meter characteristic evaluation test apparatus according to claim 3, wherein the vacuum pump is connected to an exhaust port of the servo valve. Connect the other end of the pipeline closed at one end to the downstream side of the gas meter,
A gas meter characteristic evaluation test method, wherein a gas having an arbitrary pressure waveform is supplied to the upstream side of the gas meter by a pressure control device.