JP2020063932A - Purge determination device and method for controlling the same - Google Patents

Abstract

To provide a purge determination device capable of more precisely determining switching of a gas type while reducing operation costs, and to provide a method for controlling the purge determination device.SOLUTION: A purge determination device 1 includes: a flow path 10 connected to a gas flow outlet side of a gas meter; an ultrasonic sensor 20 for transmitting and receiving ultrasonic signals to and from the flow path 10; a measurement part 51 for measuring propagation time until an ultrasonic signal is received after it is transmitted by the ultrasonic sensor 20; and a determination part 52 for determining switching of a gas type based on propagation time measured by the measurement part 51. The determination part 52 determines switching of a gas type based on excess of a difference between the maximum propagation time and the minimum propagation time measured by the measurement part 51 over a purge determination value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a purge determination device and its control method.

  Conventionally, in purging work when replacing a gas meter, a method has been proposed in which a gas recovery container is connected to a gas discharge port provided in a downstream pipe of the gas meter to recover air in the meter (for example, see Patent Document 1). . Furthermore, there is also a construction method in which a gas concentration meter with a semiconductor sensor is connected between the gas outlet and the gas recovery container, and the gas recovery container is used efficiently with a minimum purge amount based on the gas concentration indicated by the gas concentration meter. It has been proposed (see, for example, Patent Document 2).

JP, 2011-202926, A JP, 2017-106882, A

  By the above two methods, the purging work when replacing the gas meter can be performed safely and efficiently. However, the semiconductor sensor requires maintenance every year and must be replaced every year. Therefore, a gas concentration meter that uses an ultrasonic sensor instead of the semiconductor sensor is under study. This is because the ultrasonic sensor can be operated without maintenance, for example, for 10 years, so that the operation cost can be significantly reduced.

  However, the propagation time of the ultrasonic signal tends to be approximately the same for the air at high temperature and the fuel gas (specifically, 13A gas) at low temperature. Therefore, even if an attempt is made to determine the gas type switching by measuring the propagation time with a densitometer (purge determination device) equipped with an ultrasonic sensor, it may not be possible to make an accurate determination.

  The present invention has been made to solve such a conventional problem, and an object thereof is to be able to more accurately determine the switching of gas species while reducing the operating cost. A purge determination device and a control method thereof are provided.

  The present invention comprises a flow channel connected to a gas outlet side of a gas meter, and an ultrasonic sensor for transmitting and receiving an ultrasonic signal to and from the flow channel. The ultrasonic sensor transmits an ultrasonic signal. The switching of gas species is determined based on the propagation time from the reception to the reception. In this case, the present invention determines the switching of gas species based on the fact that the difference between the measured maximum propagation time and the minimum propagation time exceeds the purge determination value.

  Advantageous Effects of Invention According to the present invention, it is possible to provide a purge determination device and a control method thereof that can determine the switching of gas types with higher accuracy while reducing the operating cost.

It is a block diagram of a purge system including a purge determination device according to an embodiment of the present invention. It is a block diagram which shows the detail of the purge determination apparatus shown in FIG. It is a conceptual diagram for demonstrating a 1st method. It is a conceptual diagram for demonstrating a 2nd method. It is a flow chart which shows the control method of the purge judgment device concerning this embodiment.

  Hereinafter, the present invention will be described along with preferred embodiments. The present invention is not limited to the embodiments described below, and can be modified as appropriate without departing from the spirit of the present invention. Further, in the embodiment described below, there is a part where illustration and description of a part of the configuration are omitted, but for details of the omitted technology, within a range in which there is no contradiction with the content described below, It goes without saying that publicly known or well-known techniques are appropriately applied.

  FIG. 1 is a configuration diagram of a purge system including a purge determination device according to an embodiment of the present invention. As shown in FIG. 1, the purge system 100 according to the present embodiment is connected to the gas outlet GM2 side of a gas meter GM including a gas inlet GM1 and a gas outlet GM2 to determine an air purge in the gas meter GM. And a purge determination device 1 and a gas recovery container 2.

  The purge determination device 1 is a device for determining whether or not the air that enters when the gas meter GM is replaced has been purged from inside the gas meter GM. The gas recovery container 2 is a container for recovering the fuel gas flowing out at the time of the purge determination. The inside of the gas recovery container 2 is, for example, evacuated, and the fuel gas (further, air) is recovered by utilizing vacuum drawing.

  FIG. 2 is a block diagram showing the details of the purge determination device 1 shown in FIG. The purge determination device 1 includes a flow path 10, two ultrasonic sensors 20, a transmission circuit 30, a reception circuit 40, and a microcomputer (hereinafter, μCOM) 50.

  The flow path 10 has an inlet side connected to the gas outlet GM2 side of the gas meter GM and an outlet side connected to the gas recovery container 2.

  The two ultrasonic sensors 20 transmit / receive ultrasonic signals to / from the flow path 10, and are configured by, for example, piezoelectric vibrators. Such an ultrasonic sensor 20 is a so-called V-pass type sensor that is arranged at a predetermined distance in the longitudinal direction of the flow channel 10 and is arranged at a predetermined angle with respect to the gas flow direction Y. There is. The ultrasonic sensor 20 is not limited to the V pass, and may be a so-called Z pass type.

  Further, the two ultrasonic sensors 20 are connected to the transmission circuit 30 and the reception circuit 40. The transmission circuit 30 drives one of the two ultrasonic sensors 20 to emit an ultrasonic signal under the control of the μCOM 50.

  The receiving circuit 40 has a built-in amplifier (amplifying means) 41 that amplifies the ultrasonic signal received by the other of the two ultrasonic sensors 20 to a predetermined intensity. The amplification degree of the amplifier 41 is adjusted by the μCOM 50.

  In such a purge determination device 1, the transmission circuit 30 drives one of the two ultrasonic sensors 20 to transmit an ultrasonic signal. The transmitted ultrasonic signal is received by the other ultrasonic sensor 20 and amplified by the amplifier 41 in the receiving circuit 40 to a predetermined intensity. Further, the purge determination device 1 is configured to perform the above-described transmission of the ultrasonic signal from both the upstream ultrasonic sensor 20 and the downstream ultrasonic sensor 20 by changing the timing.

  The μCOM 50 controls the entire purge determination device 1, and includes a measurement unit (measurement unit) 51, a determination unit (determination unit) 52, and a pressure detection unit (pressure detection unit) 53.

  The measuring unit 51 measures the propagation time from the transmission of the ultrasonic signal by the ultrasonic sensor 20 to the reception of the ultrasonic signal. The propagation time changes depending on the flow velocity of the gas flowing through the flow path 10. Further, as will be described later, since the purge determination device 1 according to the present embodiment determines the switching of gas species, it is preferable to cancel the influence of the flow velocity on the propagation time. Therefore, in the present embodiment, it is preferable that the measuring unit 51 adopts an average value of the propagation time of the ultrasonic signal from the upstream side and the propagation time of the ultrasonic signal from the downstream side.

  Furthermore, if possible, a separate flow velocity sensor is provided, and the flow velocity component indicated by the flow velocity sensor is set for either the propagation time of the ultrasonic signal from the upstream side or the propagation time of the ultrasonic signal from the downstream side. It may be adjusted and the time after the adjustment may be adopted. In addition, due to the structure of the purge determination device 1 and the gas recovery container 2, if a constant flow rate of gas can be made to flow through the flow path 10, adjustment may be performed according to the constant flow rate.

  The determination unit 52 determines switching of gas species based on the propagation time measured by the measurement unit 51. The propagation time of ultrasonic signals tends to differ depending on the gas species. Therefore, the determination unit 52 will determine the switching of the gas species based on the propagation time. Further, the determination unit 52 also determines whether the air purge of the gas meter GM is completed based on the switching of the gas type.

  The pressure sensor 60 is provided facing the flow path 10 and outputs a signal according to the gas pressure in the flow path 10. The pressure detection unit 53 detects the gas pressure in the flow path 10 based on the signal from the pressure sensor 60.

  Here, the propagation time of the ultrasonic signal tends to be approximately the same for the air at high temperature and the fuel gas (specifically, 13A gas) at low temperature. More specifically, the acoustic velocity of air at 65 ° C. (propagation time is a value obtained by dividing the distance between sensors by the acoustic velocity) is 368 m / s, and the acoustic velocity at −30 ° C. is 312 m / s. On the other hand, the sound velocity at 65 ° C. of 13A gas is 434 m / s, and the sound velocity at −30 ° C. is 368 m / s. Therefore, the sound speeds of 65 ° C. air and −30 ° C. 13A gas are almost the same. For this reason, there is a possibility that even if an attempt is made to determine the gas type switching by measuring the propagation time, the determination may not be accurate.

  Therefore, the purge determination device 1 according to the present embodiment is configured to determine gas type switching by the following two methods.

  First, the first method will be described. In the first method, switching of gas species is determined based on the propagation time. FIG. 3 is a conceptual diagram for explaining the first method. First, it is assumed that, in the same temperature environment, 13A gas and air flow in the flow path 10 of the purge determination device 1 at a constant flow rate in the order of 13A gas, air, and 13A gas.

  First, from time 0 to t31, 13A gas is flowing in the flow path 10. At this time, the propagation time is about time A. Next, at time t31, air begins to flow into the flow path 10. As a result, the inside of the flow path 10 becomes a mixed gas state, and the propagation time changes from time A to time B. Then, at time t33, only air flows in the flow path 10, and the propagation time stabilizes near time B.

  Next, at time t34, the 13A gas begins to flow into the flow path 10 again. As a result, the inside of the flow path 10 is again in a mixed gas state, and the propagation time changes from time B to time A. After that, at time t36, only the 13A gas flows in the flow channel 10, and the propagation time stabilizes near time A. After this time t36, it is certain that the air has escaped from the gas meter GM, and the air purge is completed.

  Here, the purge determination device 1 according to the present embodiment is configured to store the maximum value and the minimum value of the propagation time. More specifically, it is preferable that the μCOM 50 of the purge determination device 1 performs the measurement once every 2 seconds and stores the maximum value and the minimum value of the moving average values of the plurality of times of the measurement. This is because noise can be suppressed. Then, the determination unit 52 determines that the gas type has changed, for example, when the difference between the maximum value and the minimum value exceeds the predetermined purge determination value. The determining unit 52 may determine that the gas type has changed not only when the difference between the maximum value and the minimum value exceeds a predetermined purge determination value, but also after a predetermined time from the time when the difference exceeds the purge determination value. .

  Referring to FIG. 3, first, from time 0 to t31, since the propagation time is stable at time A, the maximum value and the minimum value of the propagation time are near time A. Next, after time t31, a mixed gas state is entered, so the maximum value of the propagation time is sequentially updated. Then, for example, at time t32 between time t31 and time t33, the difference between the maximum value and the minimum value exceeds the purge determination value. As a result, the determination unit 52 determines that the gas type has been switched.

  When the determination unit 52 determines that the gas type has been switched, the μCOM 50 resets the stored maximum value and minimum value. Here, assuming that the propagation time at time t32 is time C, the minimum value is around time C from time t32 to time t33. On the other hand, since the propagation time is time B at time t33, the maximum value is near time B.

  After that, until time t34, the state in which the maximum value is around time B and the minimum value is around time C is maintained. Then, after the time t34, the mixed gas state is set, and therefore the minimum value of the propagation time is updated. Then, for example, at time t35 between time t34 and time t36, the difference between the maximum value and the minimum value exceeds the purge determination value. As a result, the determination unit 52 determines that the gas type has been switched.

  The sound velocity difference between the 13A gas and the air at 65 ° C is 66 m / s, and the sound velocity difference at -30 ° C is 56 m / s. Therefore, in the purge determination device 1 according to the present embodiment, it is preferable to set the purge determination value to a time that reflects about 50 m / s, for example.

  Next, the second method will be described. In the second method, switching of gas species is determined based on the amplification degree and the pressure. FIG. 4 is a conceptual diagram for explaining the second method. In the example shown in FIG. 4, the inside of the flow path 10 of the purge determination device 1 is filled with air, mixed gas, filled with 13A gas, vacuum, and filled with 13A gas. It shows the case of changing in the order of.

First, from time 0 to t41, 13A gas is flowing in the flow path 10. At this time, the amplification degree becomes the value D _G and the pressure becomes the D _P. Next, at time t41, air begins to flow into the flow path 10. As a result, the inside of the flow path 10 is in a mixed gas state. In the mixed gas state, ultrasonic signals are repeatedly attenuated by being reflected and refracted. Therefore, the amplification degree tends to increase, and reaches the maximum amplification degree E _G at time t42, for example.

After time t42, the proportion of air in the gas in the flow channel 10 increases, and the amplification degree gradually decreases from the maximum amplification degree E _G. Then, at time t43, the amplification degree shows the value F _G. Then, at time t43, only air flows in the flow path 10, and the amplification degree stabilizes near the value F _G. During this period, the pressure maintains the value D _P.

Next, at time t44, for example, the valve on the upstream side of the purge determination device 1 is closed. In this case, the gas does not flow from the gas meter GM side, but the gas is drawn from the gas recovery container 2. Therefore, the inside of the flow path 10 approaches a vacuum. Since the ultrasonic signal tends to be attenuated in the vacuum state, for example, the amplification degree reaches the maximum amplification degree E _G at time t45.

Thereafter, the 13A gas is opened upstream of the valve of the purge determination apparatus 1 at time t45 is as has flowed, the amplification degree gradually decreases gradually from a maximum amplification of E _G, the channel 10 is filled with a 13A gas When the time t46 is reached, the value stabilizes at the value D _G. In addition, from time t44 to t46, since the inside of the flow path 10 approaches the vacuum state, the pressure becomes a state in which the value E _P or the like is lower than the value D _P.

Here, the determination unit 52 of the purge determination device 1 according to the present embodiment monitors the amplification degree and the pressure, for example, the amplification degree is equal to or higher than the predetermined amplification degree TH _G , and the pressure is the predetermined pressure TH _P. When the above conditions are detected, it is determined that the gas species has changed. The determination unit 52 determines that not only the time when the state where the amplification degree is equal to or higher than the predetermined amplification degree TH _G and the pressure is equal to or higher than the predetermined pressure TH _P is detected, but also after the predetermined time from the time when the gas is detected. It may be determined that the species has changed. The predetermined amplification degree TH _G is set to a high value less than E _G than the value D _G In the example shown in FIG. 4, are set to high than the value D _P than the predetermined pressure TH _P value E _P .

Describing along FIG. 4, first, at time 0 to t41, the determination unit 52 determines that the gas type has changed because the pressure is equal to or higher than the predetermined pressure TH _P but the amplification degree is less than the predetermined amplification degree TH _G. Judge not to. Then, at time t41~t43 with reaching the maximum degree of amplification E _G in the amplification degree of the time t42, since it maintains the value D _P is the pressure, the determination unit 52 determines that the gas species is changed.

After that, the amplification degree reaches the maximum amplification degree E _G at the time t45 from the time t44 to the time t46. However, since the pressure drops to the value E _P , the determination unit 52 determines that the gas species has not changed (vacuum state).

  The purge determination device 1 according to the present embodiment determines the gas type switching by the first and second methods as described above, and determines the purge completion based on this switching. Specifically, the determination unit 52 of the purge determination device 1 determines that the purge is completed, for example, when the gas type switching is determined twice. Further, when the determination unit 52 determines that the gas type is switched after a lapse of a specified time (for example, the time after the first switching) after detecting the flow of gas in the flow path 10, the determination unit 52 completes the purge. May be determined. Further, the determination unit 52 may determine the completion of purge based on whether the propagation time has become longer or shorter when it is determined that the gas type has been switched.

  Next, a control method of the purge determination device 1 according to the present embodiment will be described. FIG. 5 is a flowchart showing a control method of the purge determination device 1 according to this embodiment.

  First, the measurement unit 51 measures the propagation time (S1). Next, the μCOM 50 determines whether or not the propagation time (preferably a moving average of a plurality of times) measured in step S1 exceeds the stored maximum value (S2). When the propagation time (preferably a moving average of a plurality of times) exceeds the stored maximum value (S2: YES), the μCOM 50 updates the maximum value (S3). And a process transfers to step S6.

  When the propagation time (preferably multiple moving averages) does not exceed the stored maximum value (S2: NO), the μCOM50 determines the propagation time (preferably multiple moving averages) measured in step S1. , It is determined whether the value is below the stored minimum value (S4). When the propagation time (preferably a moving average of a plurality of times) falls below the stored minimum value (S4: YES), the μCOM 50 updates the minimum value (S5). And a process transfers to step S6.

  If the propagation time (preferably a moving average of a plurality of times) is not lower than the stored minimum value (S4: NO), the μCOM 50 does not update the maximum value or the minimum value, and the process proceeds to step S6. To do.

  In step S6, the determination unit 52 determines whether the difference between the stored maximum value and minimum value exceeds the purge determination value (S6). When the difference exceeds the purge determination value (S6: YES), the determination unit 52 determines the switching of the gas type (S7). In the process of step S7, the determination unit 52 determines that the gas type has been switched when the determination is “YES” in step S6 and after a predetermined time from that time.

On the other hand, when the difference does not exceed the purge determination value (S6: NO), the determination unit 52 determines whether the amplification degree of the amplifier 41 is the predetermined amplification degree TH _G or more (S9). When the amplification degree is not equal to or higher than the predetermined amplification degree TH _G (S9: NO), the process shown in FIG. 5 ends.

When the amplification degree is equal to or higher than the predetermined amplification degree TH _G (S9: YES), the pressure detection unit 53 detects the pressure (S10), and the determination unit 52 determines that the pressure detected in step S10 is equal to or higher than the predetermined pressure TH _P. It is determined (S11). If the pressure is less than the predetermined pressure TH _P (S11: NO), the determination unit 52 determines that the vacuum state, the process shown in FIG. 5 is ended.

On the other hand, if the pressure is equal to or greater than the predetermined pressure TH _P (S11: YES), the determination unit 52 determines the switching of the gas species (S7).

  After step S7, the μCOM 50 resets the stored maximum value and minimum value (S8). Then, the process shown in FIG. 5 ends.

  As described above, according to the purge determination device 1 and the control method thereof according to the present embodiment, the gas type is switched based on the fact that the difference between the maximum propagation time and the minimum propagation time exceeds the purge determination value. To judge. Here, a state in which the first gas (13A gas in this embodiment) is flowing in the flow passage 10 of the purge determination device 1 and a second gas (air in this embodiment) is the flow passage of the purge determination device 1 The propagation time changes in the state of flowing 10 and the difference between the maximum propagation time and the minimum propagation time tends to increase. Therefore, the gas type switching can be determined by determining whether or not the difference exceeds the purge determination value. Moreover, the judgment based on the difference does not mean the judgment of the propagation time value itself which is affected by the temperature, but the effect of the temperature can be canceled and the switching of the gas species can be judged. In addition, since the determination is made based on the propagation time of the ultrasonic sensor 20, it is possible to suppress a steep rise in the operating cost of the semiconductor sensor. Therefore, it is possible to more accurately determine the switching of the gas species while reducing the operating cost.

Further, switching of the gas type is determined based on the detection of the state where the amplification degree is equal to or higher than the predetermined amplification degree TH _G and the detected pressure is equal to or higher than the predetermined pressure TH _P. Here, the amplification degree tends to increase in a mixed gas state or a vacuum state. Further, when the pressure is equal to or higher than the predetermined pressure, it can be determined that at least the vacuum state is not established. Therefore, it can be said that a state where the amplification degree is equal to or higher than the predetermined amplification degree TH _G and the pressure is equal to or higher than the predetermined pressure TH _P is a mixed gas state. Since the determination can be made, the switching of the gas species can be determined more accurately.

  Although the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment, and changes may be made without departing from the spirit of the present invention, and other suitable changes are possible within a possible range. You may combine the technology of.

  For example, the purge determination apparatus 1 according to the present embodiment determines switching between the 13A gas and air, but the present invention is not limited to this, and the target gas may be another gas. In addition, the purge determination device 1 may not be connected to the gas recovery container 2. Furthermore, the purge determination device 1 may perform only the first method or the second method described above.

1: Purge determination device 10: Flow path 20: Ultrasonic sensor 41: Amplifier (amplification means)
51: Measuring unit (measuring means)
52: Judgment unit (judgment means)
53: Pressure detector (pressure detector)
GM: gas meter GM2: gas outlet TH _P: predetermined pressure TH _G: a predetermined amplification degree

Claims (3)

A flow path connected to the gas outlet side of the gas meter, an ultrasonic sensor that transmits and receives ultrasonic signals to and from the flow path, and propagation from the time when the ultrasonic signal is transmitted by the ultrasonic sensor until it is received. A purge determination device comprising a measuring means for measuring time, and a determining means for determining switching of gas species based on the propagation time measured by the measuring means,
The purge determination is characterized in that the determination unit determines switching of gas species based on that the difference between the maximum propagation time and the minimum propagation time measured by the measurement unit exceeds a purge determination value. apparatus. Amplifying means for amplifying the ultrasonic signal received by the ultrasonic sensor to a predetermined strength,
Further comprising a pressure detection means for detecting the pressure in the flow path,
The determination means detects, after the measurement by the measurement means is started, a state in which the amplification degree in the amplification means is equal to or higher than a predetermined amplification degree and the pressure detected by the pressure detection means is equal to or higher than a predetermined pressure. The purge determination device according to claim 1, wherein the switching of the gas type is determined based on the above. A flow path connected to the gas outlet side of the gas meter, and an ultrasonic sensor that transmits and receives an ultrasonic signal to and from the flow path, until the ultrasonic signal is transmitted from the ultrasonic sensor until it is received. A method of controlling a purge determination device having a measurement step of measuring a propagation time of, and a determination step of determining purge completion based on a change in the propagation time measured in the measurement step,
In the determination step, it is determined that the gas type is switched based on that the difference between the maximum propagation time and the minimum propagation time measured in the measurement step exceeds the purge determination value. Control method of purge determination device.

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