JP2013210345A - Gas meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas meter superior in cost and suitable for a size reduction as a charging gas meter configured to measure heat quantity.SOLUTION: A gas meter includes: a flow path 3 into which gas 2 flows; an ultrasonic sensor 41 for detecting a pair of propagation times when an ultrasonic wave propagates in a flow of the gas 2; a temperature sensor 42 for measuring temperature of the gas 2; acoustic velocity deriving means 21 for determining acoustic velocity of the gas 2 from the pair of propagation times; and flow velocity deriving means 11 for determining flow velocity. The gas meter further includes: instantaneous heat quantity deriving means 22 for determining instantaneous heat quantity of the gas based on an acoustic velocity-heat quantity relationship index from the acoustic velocity of the gas 2 determined by the acoustic velocity deriving means 21; passing volume per unit time deriving means 13 for deriving a passing volume per unit time of the gas 2 based on the flow velocity; and passing heat quantity per unit time deriving means 23 for deriving the heat quantity of the gas 2 from the instantaneous heat quantity and the passing volume per unit time.

Description

  The present invention relates to a gas meter installed in each dwelling unit and used for charging a gas fee.

  Currently, the gas charge for each unit is based on the amount of gas (integrated flow rate) used in each unit for a certain period. The reason why such a system is adopted is that, in Japan, the gas supplied to each dwelling unit is strictly adjusted on the gas supply side so as to have a certain amount of heat. This is because if the amount is known, the total amount of heat of the gas used is also clarified, and charging can be performed appropriately. Based on such circumstances, the above-described gas meter that is currently popular is configured to measure only the amount of gas used.

  By the way, in recent years, biogas has been used as an energy source to replace fossil fuels, and in the future, it is expected that gas will be supplied to each dwelling unit from biogas plants established in various places. Is done. In general, the adjustment of the calorific value of gas requires a large amount of cost. Therefore, the heat calorific value adjustment accuracy that is considerably relaxed compared to the conventional calorie calorie adjustment accuracy is adopted and supplied to each dwelling unit. There is a possibility that the calorific value of the gas will fluctuate in each region or each date.

  That is, in the future, there is a possibility that gases having different heat amounts will be supplied to each dwelling unit. In this case, the current gas meter that measures only the gas amount cannot correctly grasp the total heat amount of the used gas and cannot charge appropriately. On the other hand, the apparatus described in Patent Document 1 is known as an apparatus for measuring the amount of heat of high-pressure gas.

Japanese Patent Application No. 8-343015

  However, the calorific value measuring device described in Patent Document 1 is considered to be provided in a gas manufacturing facility, and is a large-scale installation in each general dwelling unit. It is not clear whether a suitable configuration is suitable.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas meter that is excellent in cost and suitable for downsizing as a gas meter for billing configured to be able to measure the amount of heat. is there.

The characteristic configuration of the gas meter according to the present invention includes a flow path through which a measurement target gas flows,
A pair of ultrasonic transceivers;
An ultrasonic sensor that captures in two directions the propagation time of the ultrasonic wave propagating in the flow of the measurement target gas from one ultrasonic transceiver to the other ultrasonic transceiver;
A temperature sensor for measuring the temperature of the measurement target gas,
From the pair of propagation times obtained by the ultrasonic sensor, sonic speed deriving means for obtaining the sound speed of the measurement target gas, and flow velocity deriving means for obtaining the flow speed of the measurement target gas,
Instantaneous heat quantity deriving means for deriving the instantaneous heat quantity of the measurement target gas based on the sound speed-heat quantity relationship index obtained as the relationship between the sound speed and the heat quantity in the standard state of the measurement target gas and the sound speed obtained by the sound speed deriving means. Prepared,
Unit time passage volume deriving means for deriving a unit time passage volume of the measurement target gas passing through the flow path per unit time from the flow velocity obtained by the flow velocity deriving means, the cross-sectional area of the flow path, and the unit time. When,
Based on the instantaneous heat amount and the unit time passage volume, comprising unit time passage heat amount deriving means for deriving a unit time passage heat amount of the measurement target gas passing through the flow path per unit time,
At least, an external output means for outputting the unit-time passing heat amount to the outside is provided.

  According to the above characteristic configuration, the sound velocity and flow velocity of the measurement target gas can be obtained from the pair of propagation times obtained by the ultrasonic sensor, and the calorific value of the measurement target gas can be obtained based on the sound velocity and the flow velocity. it can. Therefore, the instantaneous heat quantity of the measurement target gas flowing through the flow path can be measured only by the ultrasonic sensor and the temperature sensor. That is, it is possible to provide a gas meter that is excellent in cost and suitable for downsizing as a billing gas meter configured to measure the amount of heat.

  Here, “sound speed” in the present invention means the propagation speed of sound waves in gas.

  Further, it is preferable to have a storage means for storing the sonic velocity-caloric relationship index created based on the sonic velocity in the standard state of each of a plurality of standard gases whose calories are known and have different compositions. Here, the standard state in the present application refers to a state at 0 ° C. and 1 atm as described later.

  According to the above characteristic configuration, the capacity required for the storage unit can be reduced, and the instantaneous calorific value can be quickly derived based on the sonic velocity-caloric relationship index. That is, it is possible to provide a gas meter that is excellent in cost and suitable for downsizing as a billing gas meter configured to measure the amount of heat.

Here, over a plurality of the unit time, comprising a calorific value integrating means for obtaining a calorific value integrated value obtained by integrating the unit time passing heat amount,
It is preferable that the integrated value of heat is output from the external output means. According to such a characteristic structure, it is useful at the time of meter reading of a gas meter.

  In addition, it is preferable that the unit time passing volume is externally output by the external output means. According to such a characteristic configuration, it is possible to grasp the situation in the gas meter when checking the gas meter.

Further, it comprises a flow integration means for obtaining a flow integration value obtained by integrating the unit time passage volume over a plurality of the unit times,
It is preferable that the integrated flow rate value is externally output by the external output means. According to such a characteristic structure, it is useful at the time of meter reading of a gas meter.

It is a block diagram which shows schematic structure of the gas meter which concerns on embodiment of this invention. It is a block diagram which shows the detailed structure of the gas meter which concerns on embodiment of this invention. It is a figure which shows the detailed structure of the basic physical quantity detection means which concerns on embodiment of this invention. It is a figure which shows the measurement principle of a sound speed and a flow velocity. It is a figure which shows the sound speed-heat quantity relationship parameter | index in the case of deriving heat quantity from a sound speed.

1. Outline of Gas Meter An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically illustrates the configuration of a gas meter 1 of the present application. The gas meter 1 is installed in each dwelling unit or the like and includes a flow path 3 through which a gas 2 used in each dwelling unit flows. Here, the gas 2 means a gas to be measured by the basic physical quantity detection means 4 and is supplied from a gas supply source (for example, a city gas manufacturer) to each dwelling unit. Moreover, the flow path 3 is what is called a low voltage | pressure conduit | pipe, the pressure of the gas 2 which flows through the inside is less than 0.1 Mpa, and the thickness is about 5-30 cm in diameter.

  Further, the gas meter 1 includes basic physical quantity detection means 4 for detecting a physical quantity related to the gas 2 necessary for measuring the flow rate and heat quantity of the gas 2 flowing through the flow path 3. Furthermore, unit time passage volume deriving means 13 for deriving a unit time passage volume ΔV, which is the volume of the gas 2 passing through the flow path 3 per unit time, based on the physical quantity detected by the basic physical quantity detection means 4, and unit time A unit time passage heat amount deriving means 23 for deriving a unit time passage heat amount ΔQ that is the amount of heat of the gas 2 passing through the flow path 3 is provided. Here, “unit time” means a measurement interval of the flow rate and heat quantity of the gas 2 and is a predetermined value. The unit time may be set, for example, between 1 and 5 seconds. In this embodiment, 2 seconds is set. Hereinafter, the unit time is represented by Δt. Further, the gas meter 1 includes a flow rate integrating means 14 for integrating the unit time passage volume ΔV of the gas 2 derived by the unit time passage volume deriving means 13 over a plurality of unit times Δt, and a plurality of unit times Δt. And a calorific value accumulating unit 24 for accumulating the unit 2 passing calorific value ΔQ of the gas 2 derived by the unit-time passing calorie deriving unit 23. These means and various means to be described later are constructed with a microcomputer 5 including a microprocessor and a semiconductor memory as a main device.

  In addition, the gas meter 1 is provided with external output means 6 that can output numerical values and the like to the outside so that the operator can visually confirm the state of the gas meter 1 during operations such as meter reading and maintenance inspection. In this embodiment, the external output means 6 includes a unit time passage heat quantity ΔQ derived by the unit time passage heat quantity derivation means 23, an integrated value ΣΔQ of the heat quantity accumulated by the heat quantity accumulation means 24, and a unit time passage volume derivation means 13. And the flow rate integrated value ΣΔV, which is the integrated value of the unit time pass volume integrated by the flow rate integration means 14, is displayed.

2. Detailed configuration of gas meter 2-1. Basic Physical Quantity Detection Means FIG. 2 shows a detailed configuration of the gas meter 1 of the present application. In the present embodiment, the gas meter 1 includes an ultrasonic sensor 41 and a temperature sensor 42 that measures the temperature T of the gas 2 as the basic physical quantity detection means 4. The ultrasonic sensor 41 includes a pair of ultrasonic transmitters / receivers 51 (FIG. 3), and determines the propagation time for ultrasonic waves to propagate through the flow of gas 2 from one ultrasonic transmitter / receiver 51 to the other ultrasonic transmitter / receiver 51. Each unit time Δt is configured to be captured in both directions.

  The ultrasonic sensor 41 is configured to obtain a pair of propagation times t1 and t2. A detailed configuration of the ultrasonic sensor 41 will be described with reference to FIGS. 3 and 4. The ultrasonic sensor 41 includes a pair of ultrasonic transmitters / receivers 51 arranged in two locations, upstream and downstream, along the flow path 3. Here, since the pair of ultrasonic transceivers 51 are arranged at different positions in the axis Z direction of the flow path 3, the ultrasonic waves passing between them are affected by the flow velocity v of the gas 2, and from the upstream side. The propagation time of the ultrasonic wave propagated downstream is accelerated, and vice versa.

  In the ultrasonic sensor 41 in the present embodiment, the propagation time in which the ultrasonic wave propagates from the one ultrasonic transmitter / receiver 51 to the other ultrasonic transmitter / receiver 51 in the flow of the product gas can be captured in both directions. (Here, the propagation time of ultrasonic waves from the upstream side to the downstream side (forward propagation time) is t1, and the propagation time of ultrasonic waves propagating in the reverse direction (reverse propagation time) is t2. And)

2-2. Derivation of the unit time passage volume ΔV In order to derive the unit time passage volume ΔV, the gas meter 1 includes a flow velocity deriving means 11 for obtaining the flow velocity v of the gas 2 from the pair of propagation times t1 and t2 obtained by the ultrasonic sensor 41. I have. The unit time passage volume deriving means 13 is configured to obtain the unit time passage volume ΔV from the flow velocity v obtained by the flow velocity deriving means 11, the cross-sectional area S of the flow path 3 and the unit time Δt.

  More specifically, the gas meter 1 calculates the instantaneous flow rate vS (the instantaneous value of the flow rate at the measurement timing by the ultrasonic sensor 41), which is the product of the flow velocity v obtained by the flow velocity deriving means 11 and the cross-sectional area S of the flow path 3. The required instantaneous flow rate deriving means 12 is provided. The unit time passage volume deriving unit 13 is configured to obtain, as the unit time passage volume ΔV, vSΔt that is the product of the instantaneous flow rate vS obtained by the instantaneous flow rate deriving unit 12 and the unit time Δt.

  Here, the process in which the flow velocity deriving means 11 derives the flow velocity v of the gas 2 from the pair of propagation times t1 and t2 is as follows. As shown in FIG. 4, the pair of ultrasonic transmitters / receivers 51 provided in the ultrasonic sensor 41 has a fixed positional relationship, so that the propagation times t1 and t2 for propagating between the ultrasonic transmitters / receivers 51 with each other are fixed. Is represented by Formula 1 and Formula 2 shown in FIG. Here, L is the distance of the propagation path shown in FIG. 4, Z is the axial direction of the tubular flow path 3, C is the flow velocity of the gas 2, and v is the speed of sound in the gas 2.

  Since Equations 1 and 2 are binary simultaneous equations, as shown in Equations 3 and 4, the sound velocity C and the flow velocity v can be obtained from a pair of propagation times t1 and t2. That is, the above-described flow velocity deriving unit 11 obtains the flow velocity v from the pair of propagation times t1 and t2 by performing the processing of Equation 3.

2-3. Derivation of the unit time passage heat amount ΔQ The gas meter 1 obtains the sonic velocity derivation means for obtaining the sonic velocity C in the gas 2 from the pair of propagation times t1 and t2 obtained by the ultrasonic sensor 41 in order to derive the unit time passage heat amount ΔQ. 21 and a temperature sensor 42 for measuring the temperature T of the gas 2 passing through the flow path 3. Further, the gas meter 1 determines the gas 2 based on the sound speed-heat quantity relationship index f (C ₀ ) obtained as a relation between the sound speed C ₀ and the heat quantity in the standard state of the gas 2 and the sound speed C obtained by the sound speed deriving means 21. Instantaneous heat quantity deriving means 22 for deriving the instantaneous heat quantity Q is provided.
More specifically, the sound speed C obtained by the sound speed deriving means 21 is converted into the sound speed C ₀ in the standard state using the temperature T of the gas 2 acquired by the temperature sensor 42 by the standard sound speed deriving means 21x, and the instantaneous heat quantity is derived. The means 22 derives the instantaneous heat quantity Q from the sound speed-heat quantity relation index f (C ₀ ) based on the sound speed C ₀ .

Further, the unit time passage heat quantity deriving means 23 is based on the instantaneous heat quantity Q derived by the instantaneous heat quantity derivation means 22 and the unit time passage volume ΔV derived by the unit time passage volume derivation means 13. It is comprised so that (DELTA) Q may be calculated | required.
More specifically, the unit time passage volume ΔV derived by the unit time passage volume deriving unit 13 is the unit in the standard state using the temperature T of the gas 2 acquired by the temperature sensor 42 by the unit time passage standard volume deriving unit 13x. Converted into the time passage volume ΔV ₀ , the unit time passage heat quantity deriving means 23 derives the unit time passage heat quantity ΔQ from the unit time passage volume ΔV ₀ and the instantaneous heat quantity Q.

  Hereinafter, the derivation of the unit time passage heat quantity ΔQ by the unit time passage heat quantity derivation means 23 in the present embodiment will be described in more detail. First, the derivation of the instantaneous heat quantity Q will be described before describing the derivation of the unit time passage heat quantity ΔQ.

The gas meter 1 includes storage means 25 for storing a sonic velocity-caloric relationship index f (C ₀ ) obtained as a relationship between the sonic velocity and the calorific value of each of a plurality of gases having different calorific values and having different compositions. Here, as “a plurality of gases whose amounts of heat are known in advance and having different compositions”, a gas that can be the gas 2 passing through the flow path 3 may be selected. In the present embodiment, a gas having a heat quantity of 40 to 46 MJ / Nm ³ is selected. The speed of sound C ₀ in the standard state of these gases is as follows.

In FIG. 5, each point when the values in Table 1 are plotted on a graph in which the vertical axis indicates the amount of heat in the standard state and the horizontal axis indicates the speed of sound in the standard state (0 ° C., 1 atm), An example of the stored sound velocity-heat quantity relationship index f (C ₀ ) is shown. In the figure, a correlation line indicated by a solid line corresponds to the relationship index f (C ₀ ). In the present embodiment, the correlation line shown in FIG. 5 is represented by a primary correlation equation. Here, the primary correlation equation is obtained from the values in Table 1 by the least square method.

Further, the standard sound speed deriving means 21x the gas meter 1 comprises the sound velocity C of acoustic velocity deriving means 21 is determined, the standard state (0 ° C., 1 atm) using equation 1 is converted into acoustic velocity C ₀ at.

Here, R is a gas constant, T is an absolute temperature [K], M is a molecular weight of the gas, and γ is a specific heat ratio. In gas 2 at a certain moment, R, M, and γ have constant values, and at a certain moment, the sound velocity C of gas 2 is considered to be proportional to T ^1/2 . As described above, the standard sound speed deriving means 21x can derive the sound speed C ₀ in the standard state (0 ° C.) from the sound speed C at a certain moment and the temperature T at that time from Equation 1.

With the above configuration, as shown in FIG. 2, the instantaneous calorific value deriving means 22 instantaneously uses the sonic velocity-heat quantity relationship index f (C ₀ ) stored in the storage means 25 and the sonic velocity C ₀ derived by the standard sonic velocity deriving means 21x. The amount of heat Q is obtained.

Next, the derivation of the unit time passage heat amount ΔQ will be described. In deriving the unit time passage heat quantity ΔQ, the unit time passage standard volume deriving means 13x uses the equation 2 (ideal gas equation of state) as a standard to calculate the unit time passage volume ΔV derived by the unit time passage volume deriving means 13. Converted to a unit time passing volume ΔV ₀ in the state (0 ° C., 1 atm).

Here, the pressure P in the flow path 3 can be normally regarded as 1 atm, V corresponds to a unit time passage volume ΔV, and T is an absolute temperature. N represents the number of moles of gas 2 and R represents a gas constant. Therefore, by using the temperature T of the gas 2 measured by the temperature sensor 42, the unit time passage standard volume deriving means 13x can derive the unit time passage volume ΔV ₀ in the standard state.

The unit time passage heat quantity derivation means 23 multiplies the unit time passage volume ΔV ₀ in the standard state obtained by the unit time passage standard volume derivation means 13x by the instantaneous heat quantity Q derived by the instantaneous heat quantity derivation means 22 to thereby pass the unit time passage. The amount of heat ΔQ is derived.

  With the above configuration, the gas meter 1 according to the present invention can measure the amount of heat of the gas 2 passing through the flow path 3.

[Other Embodiments]
In the above embodiment, the unit time passage volume deriving means 13 obtains the flow velocity v by the ultrasonic sensor 41 having a configuration in which the ultrasonic transmitter / receiver 51 is arranged at two locations upstream and downstream along the flow of the flow path 3. The example in the case of being configured as described above has been described. However, the embodiment of the present invention is not limited to this. That is, as the arrangement configuration of the ultrasonic sensor 41, other known arrangement configurations such as a configuration in which the pair of ultrasonic transmitters and receivers 51 are arranged so as to obliquely cross the flow path can be used.

  The present invention can be used as a gas meter that is installed in each dwelling unit and used for charging a gas fee.

1: Gas meter 2: Gas 3: Flow path 6: External output means 7: Switching means 11: Flow velocity deriving means 13: Unit time passage volume deriving means 14: Flow rate accumulating means 21: Sonic velocity deriving means 22: Instantaneous heat quantity deriving means 23: Unit time passing heat quantity deriving means 24: heat quantity integrating means 25: storage means 41: ultrasonic sensor 42: temperature sensor 51: ultrasonic transceiver

Claims (5)

A flow path through which the gas to be measured flows,
A pair of ultrasonic transceivers;
An ultrasonic sensor that captures in two directions the propagation time of the ultrasonic wave propagating in the flow of the measurement target gas from one ultrasonic transceiver to the other ultrasonic transceiver;
A temperature sensor for measuring the temperature of the measurement target gas,
From the pair of propagation times obtained by the ultrasonic sensor, sonic speed deriving means for obtaining the sound speed of the measurement target gas, and flow velocity deriving means for obtaining the flow speed of the measurement target gas,
Instantaneous heat quantity deriving means for deriving the instantaneous heat quantity of the measurement target gas based on the sound speed-heat quantity relationship index obtained as the relationship between the sound speed and the heat quantity in the standard state of the measurement target gas and the sound speed obtained by the sound speed deriving means. Prepared,
Unit time passage volume deriving means for deriving a unit time passage volume of the measurement target gas passing through the flow path per unit time from the flow velocity obtained by the flow velocity deriving means, the cross-sectional area of the flow path, and the unit time. When,
Based on the instantaneous heat amount and the unit time passage volume, comprising unit time passage heat amount deriving means for deriving a unit time passage heat amount of the measurement target gas passing through the flow path per unit time,
A gas meter provided with an external output means for outputting at least the unit-time passing heat quantity to the outside.   The gas meter according to claim 1, further comprising a storage unit that stores the sonic velocity-caloric relationship index created based on the sonic velocity in the standard state of each of a plurality of standard gases whose calories are known and have different compositions. A calorific value integrating means for obtaining a calorific value integrated value obtained by accumulating the calorific value passing through the unit time over a plurality of the unit times,
The gas meter according to claim 1 or 2, wherein the heat integrated value is output externally by the external output means.   The gas meter according to any one of claims 1 to 3, wherein the unit time passing volume is externally output by the external output means. A flow integration means for obtaining a flow integrated value obtained by integrating the unit time passage volume over a plurality of the unit times;
The gas meter according to any one of claims 1 to 4, wherein the integrated flow rate value is externally output by the external output means.

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