JP6586351B2 - Calorific value deriving device - Google Patents

Description

  The present invention relates to a calorific value deriving device that derives the calorific value of a gas.

  In order to grasp the passing volume of the gas consumed by the consumer, the gas company arranges a gas meter at the demand point, and charges based on the passing volume of the gas measured by the gas meter. In Japan, gas operators usually control the calorific value of the gas supplied to the demand location to be constant, so the total amount of gas consumed by the consumer is based on the gas passing volume and the calorific value of the delivered gas. The calorific value can be accurately derived. Therefore, charging can be performed appropriately by measuring the specification gas volume of the consumer with a gas meter.

  However, if gas with a different calorific value is supplied to the demand location depending on the time and place, the conventional gas meter that measures only the gas passage volume correctly derives the passage calorific value based on the gas passage volume. There is a risk that it may be difficult to charge properly.

  Therefore, the gas temperature and sound velocity are measured, the calorific value of the gas in the standard state is estimated based on the measured temperature and sound velocity, the calorific value in the estimated standard state, the gas passing volume, and the gas temperature Based on the above, there has been proposed a gas meter designed to derive the passing heat generation amount (for example, Patent Document 1).

JP 2013-210344 A

  By the way, in the gas meter of the above-mentioned patent document 1, since it is premised that the supplied gas is only a hydrocarbon-based gas, when nitrogen or the like is mixed into the hydrocarbon-based gas, the temperature and the speed of sound are reduced. There was a problem that the calorific value of the gas could not be derived accurately.

  In view of such problems, the present invention provides a calorific value derivation device that can accurately derive the calorific value of a gas even in a gas containing a gas component other than a hydrocarbon system such as nitrogen. It is aimed.

In order to solve the above-described problem, the calorific value deriving device of the present invention includes an ultrasonic attenuation rate deriving unit for deriving an ultrasonic attenuation rate in a gas flow path through which a mixed gas flows for a plurality of different frequencies, and the mixed gas. And a storage unit storing an ultrasonic attenuation rate table indicating an ultrasonic attenuation rate when a plurality of frequencies are different from each other, and an ultrasonic attenuation rate deriving unit. Based on the ultrasonic attenuation rate, the ultrasonic attenuation rate table is referred to, and the component ratio deriving unit for deriving the component ratio of each component constituting the mixed gas and the component ratio deriving unit A calorific value deriving unit for deriving the calorific value of the mixed gas flowing in the gas flow path based on the component ratio of each component constituting the mixed gas and the calorific value of each component constituting the mixed gas , Wherein the composition ratio deriving unit, the in ultrasonic attenuation rate table, by obtaining a combination composition ratio of each component in the plurality of frequency coincide, derive the ratios of the components of the mixed gas To do .

Moreover, further comprising a temperature sensor for measuring the temperature of the pre SL gas mixture, wherein the ultrasonic attenuation rate table, provided for each different temperature, the composition ratio deriving unit, the measured by the temperature sensor temperature The component ratio of each component constituting the mixed gas may be derived by referring to the ultrasonic attenuation rate table corresponding to the above .

  The mixed gas may contain nitrogen in a hydrocarbon-based gas.

  According to the present invention, it is possible to provide a calorific value derivation device that can accurately derive the calorific value of gas.

It is explanatory drawing which showed the schematic structure of the gas meter system. It is the functional block diagram which showed the schematic structure of the gas meter. It is explanatory drawing which showed the structure of the ultrasonic sensor. It is the functional block diagram which showed the schematic structure of the center apparatus. It is the functional block diagram which showed the schematic structure of the gas meter of a modification. It is a figure explaining an ultrasonic attenuation rate table.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Gas meter system 100)
FIG. 1 is an explanatory diagram showing a schematic configuration of the gas meter system 100. As shown in FIG. 1, the gas meter system 100 includes a plurality of gas meters (calorific value derivation devices) 110, a plurality of gateway devices 112, and a center device 114.

  The gas meter 110 derives the passing calorific value of hydrocarbon-based (methane, propane, etc.) gas supplied to the demand point 120. The gateway device 112 collects data of one or more gas meters 110 and distributes data to the one or more gas meters 110.

  The center device 114 is configured by a computer or the like, and belongs to a manager of the gas meter system 100 such as a gas company. The center device 114 collects data of the one or more gateway devices 112 and distributes the data to the one or more gateway devices 112. Therefore, the information which the gas meter 110 arrange | positioned in every demand point 120 has can be collectively managed by the center apparatus 114. FIG.

  Here, for example, wireless communication is performed between the gateway device 112 and the center apparatus 114 through an existing communication network such as a mobile phone network including the base station 116 or a PHS (Personal Handyphone System) network. In addition, wireless communication is performed between the gas meters 110 and between the gas meter 110 and the gateway device 112 through, for example, a smart meter wireless system (U-Bus Air) using the 920 MHz band. Hereinafter, the configuration of the gas meter 110 and the center device 114 will be described in detail.

(Gas meter 110)
FIG. 2 is a functional block diagram showing a schematic configuration of the gas meter 110. The gas meter 110 includes an ultrasonic sensor unit 150, a pressure sensor 152, a cutoff valve 154, a communication circuit 156, a display unit 158, a gas meter storage unit 160, and a gas meter control unit 162. The ultrasonic sensor unit 150 includes an ultrasonic sensor 170 and a temperature sensor 172.

  FIG. 3 is an explanatory diagram showing the configuration of the ultrasonic sensor 170. The ultrasonic sensor 170 is an arrival time difference type flow meter. As shown in FIG. 3, the ultrasonic sensor 170 is located at two locations, upstream and downstream, along the flow of the gas flow path 140 (indicated by white arrows in FIG. 3). A propagation time in which ultrasonic waves propagate in the gas from one ultrasonic transmitter / receiver 170a, 170b to the other ultrasonic transmitter / receiver 170b, 170a, and a pair of arranged ultrasonic transmitter / receivers 170a, 170b; The amplitude of the ultrasonic wave can be measured bidirectionally at predetermined time intervals. The ultrasonic transceivers 170a and 170b can transmit and receive ultrasonic waves having different frequencies.

  Returning to FIG. 2, the temperature sensor 172 measures the temperature of the gas flowing through the gas flow path 140 every predetermined time. The pressure sensor 152 measures the pressure of the gas flowing through the gas flow path 140 every predetermined time. The shut-off valve 154 is composed of, for example, a solenoid valve using a solenoid or a stepping motor, and shuts off or opens the gas flow path 140. The communication circuit 156 establishes wireless communication with the gateway device 112 and other gas meters 110. The display unit 158 displays the volume of the gas that has passed through the gas meter 110 and the amount of generated heat, that is, the total amount of heat generated by the gas consumed at the demand location 120 where the gas meter 110 is provided. The gas meter storage unit 160 includes a ROM, a RAM, a flash memory, an HDD, and the like, and stores a program used for the gas meter 110 and various data.

  The gas meter control unit 162 includes a CPU and a DSP, and controls the entire gas meter 110 using a program stored in the gas meter storage unit 160. The gas meter control unit 162 includes a flow velocity / sound velocity deriving unit 180, an ultrasonic attenuation rate deriving unit 182, a mole fraction deriving unit (component ratio deriving unit) 184, a heat generation amount deriving unit 186, a flow rate deriving unit 188, and a passing heat generation amount. It functions as a deriving unit 190, a blocking unit 192, and a meter communication unit 194.

  Here, if the component (kind) of the gas flowing through the gas flow path 140 is only a hydrocarbon-based gas, and the mole fraction (component ratio) of each component constituting the gas is known in advance, the gas flow The calorific value of the gas flowing through the path 140 can be accurately derived. However, in the method described in Patent Document 1, when the molar fraction of nitrogen that does not have a calorific value varies with time, the calorific value of the gas cannot be derived accurately.

  Therefore, in the present embodiment, the molar fraction of each component of the gas (mixed gas) flowing in the gas flow path 140 is derived based on the difference in the attenuation rate of the ultrasonic wave propagated in the gas flow path 140 and is derived. Based on the mole fraction, the calorific value of the gas flowing in the gas flow path 140 is derived. Hereinafter, a specific method will be described.

なお、Ｌは一対の超音波送受信器１７０ａ、１７０ｂ間の距離を示す。 The flow velocity / sound speed deriving unit 180 transmits the ultrasonic wave propagation time t1 from the ultrasonic transmitter / receiver 170a to the ultrasonic transmitter / receiver 170b and the ultrasonic wave transmitter / receiver 170b to the ultrasonic transmitter / receiver 170a shown in FIG. The propagation time t2 of the ultrasonic wave to be acquired is acquired. Then, the flow velocity / sound velocity deriving unit 180 derives the gas flow velocity ν and the sound velocity V in the gas flow path 140 using the equation (1).

L indicates the distance between the pair of ultrasonic transceivers 170a and 170b.

  The ultrasonic attenuation rate deriving unit 182 determines one frequency among frequencies that can be transmitted from the ultrasonic transceivers 170a and 170b, and determines the one frequency determined from one ultrasonic transceiver 170a and 170b. Then, an ultrasonic wave having a predetermined amplitude is transmitted. Then, the ultrasonic attenuation rate deriving unit 182 acquires the amplitude of the ultrasonic wave received by the other ultrasonic transceivers 170b and 170a, and based on the transmitted ultrasonic wave amplitude and the received ultrasonic wave amplitude, The attenuation factor of the ultrasonic wave at the determined frequency is derived.

  Also, the ultrasonic attenuation rate deriving unit 182 derives the ultrasonic attenuation rate in the same manner for other frequencies among the frequencies that can be transmitted from one of the ultrasonic transceivers 170a and 170b. As will be described in detail later, the ultrasonic attenuation rate deriving unit 182 sets the ultrasonic attenuation rate for at least the number of frequencies obtained by subtracting 2 from the number of components of the gas constituting the mixed gas flowing in the gas flow path 140. To derive.

  The molar fraction deriving unit 184 is based on the sound velocity V of the gas derived by the flow velocity / sonic velocity deriving unit 180 and the ultrasonic attenuation rate at a plurality of frequencies derived by the ultrasonic attenuation rate deriving unit 182. The molar fraction of each component of the mixed gas flowing through 140 is derived. Hereinafter, a specific method will be described.

なお、Ｃ_Ｍｉは、混合ガス中のｉ番目の成分のモル分率である。 Since the total value of the molar fraction of the mixed gas in which the gas of a plurality of components is mixed is 1, the formula (2) can be derived.

Note that C _Mi is the molar fraction of the i-th component in the mixed gas.

なお、γは比熱比であり、Ｒは気体定数であり、Ｔは混合ガスの温度である。 Then, the sound velocity V of the gas derived by the flow velocity / sound velocity deriving unit 180 and the average molecular weight M _mix of the mixed gas can be expressed by the following equation (3).

Note that γ is a specific heat ratio, R is a gas constant, and T is the temperature of the mixed gas.

なお、Ｍ_ｉはｉ番目の成分の分子量である。 On the other hand, the average molecular weight M _mix is the sum of the values obtained by multiplying the gas molecular weight of each component of the mixed gas by the molar fraction of that component, and can be expressed as in equation (4).

M _i is the molecular weight of the i-th component.

Then, Equation (5) can be derived by combining Equations (3) and (4).

なお、Ａ_ｉ（ｆ）は、周波数がｆのときのｉ番目の成分中における超音波の減衰率であり、予め実験により求めておくことができる。 Further, when the ultrasonic frequency is f, the ultrasonic attenuation rate A _mix (f) in the mixed gas can be expressed by equation (6).

A _i (f) is the attenuation factor of the ultrasonic wave in the i-th component when the frequency is f, and can be obtained in advance by experiments.

Therefore, if the number n of components of the mixed gas is known, the components constituting the mixed gas are obtained by combining the equations (2), (5), and (6) at the frequency of the component number n-2. It is possible to derive the molar fraction C _Mi of.

  For example, if the gas components generated in the gas factory are four types of methane, ethane, propane, and nitrogen, the number of components n of the mixed gas flowing through the gas flow path 140 is four. In such a case, the ultrasonic attenuation rate deriving unit 182 derives the attenuation rate of ultrasonic waves at two different frequencies, which is a number obtained by subtracting 2 from the number of components 4 of the mixed gas.

The molar fraction deriving unit 184 includes the sound velocity V of the gas derived by the flow velocity / sound velocity deriving unit 180, the ultrasonic attenuation rate at two different frequencies derived by the ultrasonic attenuation rate deriving unit 182, and a temperature sensor. Using the temperature T measured by 172, methane that constitutes the mixed gas by combining Equation (2), Equation (5), and Equation (6) at two different frequencies, that is, a total of four equations, The molar fraction C _Mi of ethane, propane and nitrogen is derived.

なお、Ｚ_ｍｉｘは混合ガスの圧縮係数であり、例えばＪＩＳ(Japanese Industrial Standards)に規定された方法で求めることができる。 The calorific value deriving unit 186 uses the molar fraction C _Mi of each component of the mixed gas derived by the molar fraction deriving unit 184 to calculate the gas (mixed gas) flowing through the gas flow path 140 using the equation (7). A calorific value H _mix is derived.

Z _mix is a compression coefficient of the mixed gas, and can be obtained by a method defined in, for example, JIS (Japanese Industrial Standards).

  The flow rate deriving unit 188 derives the gas flow rate by multiplying the gas flow velocity ν derived by the flow velocity / sonic velocity deriving unit 180 by the cross-sectional area of the gas flow path 140. Further, the passage calorific value deriving unit 190 multiplies the gas flow rate derived by the flow rate deriving unit 188 by the calorific value of the mixed gas derived by the calorific value deriving unit 186 so that the gas passing through the gas meter 110 can be obtained. A passing calorific value, that is, a total calorific value of the gas consumed at the demand point 120 provided with the gas meter 110 is derived.

  The shut-off unit 192 controls the shut-off valve 154 to control gas supply and demand. The meter communication unit 194 exchanges information with the center device 114 through the communication circuit 156, and transmits, for example, the passing heat generation amount derived by the passing heat generation amount deriving unit 190 to the center device 114 every hour. However, the present embodiment can be realized even in a configuration that does not include the blocking unit 192 and the blocking valve 154.

(Center device 114)
FIG. 4 is a functional block diagram illustrating a schematic configuration of the center device 114. As shown in FIG. 4, the center device 114 includes a communication circuit 200, a usage amount storage unit 202, a device storage unit 204, and a center control unit 206. The communication circuit 200 establishes wireless communication with the gateway device 112 via the base station 116. The usage amount storage unit 202 includes a ROM, a RAM, a flash memory, an HDD, and the like, and stores the passing heat generation amount received from each gas meter 110 in association with the gas meter 110. Therefore, the usage amount storage unit 202 holds the transition of the past passing heat generation amount for each gas meter 110. The device storage unit 204 is composed of a ROM, a RAM, a flash memory, an HDD, and the like, similar to the usage amount storage unit 202, and stores a device 122 used via the gas meter 110, such as a flaming device, in association with the gas meter 110. .

  The center control unit 206 includes a CPU and a DSP, and controls the entire center device 114 based on information stored in the usage amount storage unit 202 and the device storage unit 204. The center control unit 206 functions as an abnormality diagnosis unit 210 and a center communication unit 212. The abnormality diagnosis unit 210 diagnoses whether or not the current passing heat generation amount is abnormal based on the transition of the past passing heat generation amount stored in the usage amount storage unit 202. The abnormality diagnosis unit 210 can also diagnose an abnormality based on the rated heat generation amount of gas in the device 122 stored in the device storage unit 204. The center communication unit 212 exchanges information with each gas meter 110 through the communication circuit 200 and receives, for example, the passing heat generation amount from the gas meter 110.

  As described above, the gas meter 110 according to the present embodiment derives ultrasonic attenuation rates at a plurality of frequencies, and configures a mixed gas flowing through the gas flow path 140 based on the derived attenuation rates and sound speeds. The molar fraction of each component is derived. Then, the calorific value of the mixed gas is derived based on the molar fraction of each component constituting the derived mixed gas. Thereby, even if it is a case where the fraction (molar fraction) of the component of the gas supplied to the gas meter 110 and the demand location 120 changes, the emitted-heat amount of gas can be derived | led-out accurately.

(Modification)
FIG. 5 is a functional block diagram showing a schematic configuration of a gas meter 300 according to a modification. As shown in FIG. 5, the gas meter 300 is different in that a mole fraction deriving unit 302 is provided instead of the mole fraction deriving unit 184.

  FIG. 6 is a diagram for explaining the ultrasonic attenuation rate table. In the gas meter 300, the molar fraction of each component constituting the mixed gas, and the ultrasonic attenuation rate when the frequency is changed, as an ultrasonic attenuation rate table as shown in FIG. It is stored in the gas meter storage unit 160. Each value of the ultrasonic attenuation rate table (indicated by “...” In the figure) indicates the molar fraction of each component constituting the mixed gas and the ultrasonic attenuation rate when the frequency is changed in advance. And is measured in advance by experiments. In FIG. 6, the mole fraction is expressed in%.

For example, the components constituting the mixed gas are methane (CH ₄ ), ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), and nitrogen (N ₂ ), and the frequency is 500 kHz and 200 kHz for each gas temperature. In addition, the attenuation rate of ultrasonic waves when the molar fraction of methane (CH ₄ ), ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ), and nitrogen (N ₂ ) is changed is measured in advance by experiment, It is stored in the gas meter storage unit 160 as an ultrasonic attenuation rate table as shown in FIG. In FIG. 6, although the molar fractions of methane (CH ₄ ), ethane (C ₂ H ₆ ), and nitrogen (N ₂ ) are shown, the total value of these molar fractions is 1 (100%). The value subtracted from this is the molar fraction of propane (C ₃ H ₈ ). Note that the frequency is an example, and any other frequency may be used as long as a difference in attenuation rate appears.

  The molar fraction deriving unit 302 reads an ultrasonic attenuation rate table corresponding to the temperature measured by the temperature sensor 172 from the gas meter storage unit 160, and a plurality of frequencies (mixed gas of the mixed gas) derived by the ultrasonic attenuation rate deriving unit 182. By using the ultrasonic attenuation rate in the number of components n-2), in the ultrasonic attenuation rate table having a plurality of different frequencies, by obtaining a combination in which the molar fractions match, the molar content of each component of the mixed gas is obtained. Deriving rate.

  As described above, in the gas meter 300, if the molar fraction of each component constituting the mixed gas and the ultrasonic attenuation rate when the frequency is changed are stored in advance as an ultrasonic attenuation rate table, the ultrasonic attenuation is achieved. By deriving the attenuation rate of the ultrasonic wave at a plurality of frequencies derived by the rate deriving unit 182, it is possible to easily derive the molar fraction of each component constituting the mixed gas.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  In the above embodiment, the gas meter control unit 162 of the gas meter 110 includes the flow velocity / sonic velocity deriving unit 180, the ultrasonic attenuation rate deriving unit 182, the mole fraction deriving unit 184, the heat generation amount deriving unit 186, and the passing heat generation amount deriving unit. 190, the flow rate / sonic velocity deriving unit 180, the ultrasonic attenuation rate deriving unit 182, the mole fraction deriving unit 184, the heat generation amount deriving unit 186, and the passing heat generation amount are added to the center control unit 206 of the center device 114. A deriving unit 190 may be provided, and the center device 114 may derive the molar fraction of the gas meter 110, the passing heat generation amount, and the like.

  In the above embodiment, in order to derive the flow velocity ν and the sound velocity V by the flow velocity / sound velocity deriving unit 180, the ultrasonic sensor unit 150, which is an ultrasonic flow meter, is provided. As long as V can be derived, any flow velocity sensor or sound velocity sensor may be provided.

  The present invention can be used for a calorific value deriving device for deriving a unit calorific value.

110 Gas meter (calorific value derivation device)
140 Gas flow path 150 Ultrasonic sensor unit 172 Temperature sensor 180 Flow velocity / sound velocity deriving unit (sound velocity deriving unit)
182 Ultrasonic attenuation rate deriving unit 184 Mole fraction deriving unit (component ratio deriving unit)
186 Calorific value deriving section

Claims (3)

For a plurality of different frequencies, an ultrasonic attenuation rate deriving unit for deriving an ultrasonic attenuation rate in the gas flow path through which the mixed gas flows,
A storage unit storing an ultrasonic attenuation rate table in which the composition ratio of each component constituting the mixed gas and the attenuation rate of ultrasonic waves when a plurality of frequencies are different from each other;
A component ratio deriving unit for deriving a component ratio of each component constituting the mixed gas with reference to the ultrasonic attenuation factor table based on the ultrasonic attenuation factor derived by the ultrasonic attenuation factor deriving unit; ,
The calorific value of the mixed gas flowing in the gas flow path based on the constituent ratio of each component constituting the mixed gas derived by the constituent ratio deriving unit and the calorific value of each component constituting the mixed gas A calorific value deriving unit for deriving
With
The component ratio deriving unit
A calorific value derivation device characterized in that, in the ultrasonic attenuation rate table, the component ratio of each component of the mixed gas is derived by obtaining a combination in which the component ratios of the components at the plurality of frequencies coincide . Further comprising a temperature sensor for measuring the temperature of the pre SL gas mixture,
The ultrasonic attenuation rate table is provided for each of a plurality of different temperatures,
The component ratio deriving unit
Referring to the ultrasonic attenuation rate table corresponding to the temperature measured by the temperature sensor, the heating value derived according to claim 1, characterized in that to derive a rate of each component constituting the gas mixture apparatus. The mixed gas, heating value derivation device according to claim 1 or 2, characterized in that it contains nitrogen in the hydrocarbon-based gas.

Images