JP2000039426A - Gas physical property measurement method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure physical properties related to the combustion of a combustible gas in real time by providing a sound velocity-deriving means or the like for obtaining the sound velocity of a gas to be measured from time when ultrasonic waves are propagated in the flow of the gas to be measured. SOLUTION: A gas to be measured flows in a specific direction in a measurement part 7. An ultrasonic wave is transmitted from one of ultrasonic transmitters/receivers to the other, and the sound velocity of the gas to be measured is obtained by a sound velocity-deriving means 18. The specific gravity of the gas to be measured is obtained from the sound velocity by a specific gravity-deriving means 20b. Regarding the specific gravity, since numeric values are related to the sound velocity of gas, the values are obtained from the sound velocity of the gas, thus obtaining the specific gravity of the gas, thus measuring the specific gravity of a product gas in real time. Also, a calorific value-deriving means 20a obtains the calorific value of the gas to be measured from the sound velocity, and an Wobbe index-deriving means 20c obtains a Wobbe index from the calorific value and the specific gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring gas properties which can be effectively used when producing or supplying a calorie-adjusted product gas or an unheated gas (a gas not calorificized). The present invention relates to a technology in which the physical properties of a gas to be measured are the specific gravity of the gas to be measured, the Wobbe index, and the like.

[0002]

2. Description of the Related Art In the production of so-called city gas, a production plant is provided with a liquefied natural gas storage facility and a liquefied petroleum gas storage facility, and a gas having a predetermined calorific value is prepared by mixing both gases. Gas (a kind of product gas) is obtained. In supplying the city gas to the consumers, the product gas whose calorific value has been adjusted is supplied, and in the supply process, the supply amount (flow rate) is measured, and a request for the gas consumption amount is obtained. In addition, for example, without providing product heat-adjusted product gas to large consumers such as heating plants and incinerator plants, supply a product gas having a calorific value within a certain range to meet demand. It has also been proposed to provide. For gas utilities, producing gas like these
In supplying the gas, it is extremely important to measure the calorific value, specific gravity, Wobbe index, burning rate index, and even gas flammability of the product gas in controlling the quality of the gas.

[0003] The flammability is roughly divided into a combustion rate index and a Wobbe index. The Wobbe index is a value obtained by dividing the calorific value of a product gas by the square root of the specific gravity. Measurement is required. Conventionally, such measurement of the specific gravity of a product gas has been performed by extracting the product gas from a production line, reducing the pressure of the sample gas to atmospheric pressure, and using a Lauter-type hydrometer or the like. When obtaining the Wobbe index, the calorific value of the gas is separately obtained, and the Wobbe index is obtained using the specific gravity obtained by the method described above.

[0004]

However, such a method has the following disadvantages. (1) Measurement is performed using a specific gravity meter that is separate from the production line, and it is not possible to measure the specific gravity, the Wobbe index, and the like in real time on the production line. (2) The measurement is performed in the atmospheric pressure state, and it may be difficult to represent the actual situation in the production line in the high pressure state. Furthermore, the combustion state of a combustible gas is determined by the Wobbe index of the gas and the burning rate index.Predicting such a combustion state in real time has conventionally been impossible to know both indices in real time. Was virtually impossible. On the other hand, the inventors of the present application have proposed measuring the calorific value by measuring the sound velocity of the gas to be measured (Japanese Patent Application No. 8-343015, Japanese Patent Application No. 8-343030, No. 8-343020. An object of the present invention is to provide physical properties (index) relating to combustion of combustible gas.
It is an object of the present invention to obtain a technique capable of measuring the combustion state in real time, and a technique capable of predicting the combustion state of the combustible gas in real time.

[0005]

To achieve the above object, a gas physical property measuring apparatus according to the present invention comprises a measuring unit into which a gas to be measured is introduced and which flows in a predetermined direction. A pair of ultrasonic transceivers are provided so as to face each other, and the propagation time during which ultrasonic waves propagate in the flow of the gas to be measured from one ultrasonic transceiver to the other ultrasonic transceiver is bi-directional. A sound velocity deriving means for obtaining the sound velocity of the gas to be measured from a pair of obtained propagation times, and a specific gravity deriving means for obtaining the specific gravity of the gas to be measured from the sound velocity obtained by the sound velocity deriving means, and outputting the obtained specific gravity. Having the target output means, the operation and effect are as follows. The gas physical property measuring device having this configuration includes a measuring unit, and the gas to be measured flows in the measuring unit in a predetermined direction. Then, the detection units of the pair of ultrasonic transceivers are set at positions facing each other. For example, the propagation direction of the ultrasonic wave is set parallel to the flow direction of the gas to be measured. Or, as shown in Japanese Patent Application No.
The structure shown in JP-A-343015 may be adopted. Therefore, the ultrasonic wave can be propagated between these detecting units from one detecting unit side to the other detecting unit side. In this configuration,
Ultrasonic waves are sent from one side of the ultrasonic transceiver to the other side, the propagation times in both directions are detected, and the sound speed of the gas to be measured is determined according to the detection results of these propagation times. This is the role of the sound velocity deriving means. When the sound velocity is obtained, the specific gravity of the gas to be measured is obtained from the sound velocity by specific gravity deriving means, and the specific gravity of the gas to be measured obtained from these means is output. Here, as for the specific gravity which is the measurement target of this gas measuring device, since this numerical value is a numerical value related to the sound speed of the gas, these numerical values are obtained from the sound speed of the gas, and the specific gravity of the gas can be obtained. . Therefore, in this device, the specific gravity of the product gas can be measured in real time.

[0006] In the configuration having the above specific gravity deriving means, there is provided a calorific value deriving means for obtaining the calorific value of the gas to be measured from the sound velocity obtained from the sound velocity deriving means described above. From the calorific value obtained from the means and the specific gravity obtained from the specific gravity deriving means, provided with a Wobbe index deriving means for obtaining the Wobbe index of the gas to be measured,
It is preferable that the output means also output the Wobbe index obtained.

That is, as a method of obtaining the Wobbe index, the propagation time of the ultrasonic wave along the flow direction of the gas to be measured is set to the propagation time from the upstream side to the downstream side and from the downstream side to the upstream side. The sound velocity of the gas to be measured is obtained from a pair of propagation times obtained in two directions, the specific gravity and calorific value of the gas to be measured are obtained from the sound velocity obtained, and the Wobbe index of the gas to be measured is obtained from the calorific value and specific gravity obtained. Ask for. When using this approach,
In a similar manner, the calorific value and specific gravity are separately obtained from the sound velocity of the gas to be measured by the calorific value deriving means and the specific gravity deriving means, and the Wobbe index can be obtained by the Wobbe index deriving means. In the case of this configuration, for example, the calorific value of the product gas and the specific gravity can be obtained. Therefore, even if the supply amount is changed, the Wobbe index, which is one of the indices of the flammability of the product gas, is calculated in real time. It can be measured continuously in real time.

The structure relating to the derivation of the Wobbe index has been described above. Hereinafter, the derivation of the combustion speed index and the combustion characteristics will be described.

1 Derivation of combustion rate index In addition to derivation of the calorific value and specific gravity via the above-mentioned sound velocity, the derivation of this index is not limited to hydrogen, carbon monoxide, and hydrocarbons other than methane in the gas to be measured. , It is necessary to determine the oxygen content. That is, in the device, hydrogen in the gas to be measured,
It is provided with a content measuring means for measuring the content of carbon monoxide, hydrocarbons other than methane, and oxygen, and the content to be measured is determined from the content measured by the content measuring means and the specific gravity obtained from the specific gravity deriving means. A combustion rate index deriving means for deriving a gas burning rate index is provided, and the output means adopts a configuration in which the calculated burning rate index is also output.
In this configuration, the structure is such that the contents of hydrogen, carbon monoxide, hydrocarbons other than methane, and oxygen in the gas to be measured can be separately and continuously measured in real time. That is, for example, sensors for these are separately provided. In this way, the combustion measurement index CP of the gas to be measured whose specific gravity d is known can be obtained by the following equation.

CP = K (1.0 H ₂ +0.6 (CO + C _m H _n ) +0.3 CH ₄ ) / sq (d) where, CP burning rate index (which is an object of derivation) Hydrogen in H ₂ gas obtained by content (%) (obtained by measurement) CO content of carbon monoxide in the gas (%) (obtained by measurement) C _m H _n content of hydrocarbons other than methane in the gas (%) (measured ) Content of methane in CH ₄ gas (%) (obtained by measurement) sq (d) Square root of specific gravity (obtained by measurement via sound speed) K Constant determined by content of oxygen in gas (obtained by measurement) Obtain a constant from the oxygen content)

According to the above method, the burning rate index of the gas to be measured can be obtained by the burning rate index deriving means.

2 Derivation of Combustion Characteristics (Estimated Combustion State) In the present application, what is referred to as combustion characteristics is what combustion takes when a gas to be measured is supplied to a predetermined combustion device. (Combustion estimation state). Regarding such combustion characteristics, FIG.
This will be described with reference to FIG. FIG. 6 is a so-called compatibility diagram in which the vertical axis represents the Wobbe index and the horizontal axis represents the combustion velocity index, and the figure is divided into a plurality of regions. This compatibility diagram is specified corresponding to the gas equipment in which the gas is used, and includes a compatible region in which good combustion can be performed, an incomplete combustion region, and a lift which belong to a predetermined boundary region. It is divided into a limit area, a back limit area, an infrared burner red heat deficient area, and an infrared burner back limit area. Here, the latter three and the two following the three are classified by device. In the present application, the expression that can represent the estimated combustion state of the gas appliance from the compatibility diagram is called a combustion characteristic. Now, as can be seen from the configuration of the compatibility diagram, the region to which the combustion belongs is based on the Wobbe index and the combustion speed index obtained in real time from the apparatus of the present invention. Determined uniquely by Therefore, the apparatus is provided with combustion characteristic deriving means for deriving the estimated combustion state of the combustible gas based on the Wobbe index and the burning rate index of the combustible gas, and is obtained by the Wobbe index deriving means described above. Wobbe index,
A configuration in which the combustion characteristic deriving means derives the estimated combustion state of the measurement target gas from the combustion rate index obtained from the previously described combustion rate index deriving means, and the output means also outputs the estimated combustion state obtained. By using, for example, the combustion characteristics of the gas to be measured can be obtained in real time. As a result, a burning speed index can be obtained, and compatibility determined by the Wobbe index and the burning speed index can be monitored. Furthermore, the compatibility of combustible gas (gas to be measured) is an important factor in monitoring a good combustion range of gas appliances, but in the present application, the calorific value and specific gravity are continuously monitored in real time. It is also possible to obtain compatibility, which is an indicator of the flammability of gas appliances, through a comprehensive measurement, and monitor and control the compatibility.

Further, the gas to be measured is preferably a mixed gas containing methane as a main component and a hydrocarbon gas other than methane. Here, the target gas mixture tends to increase its calorific value due to an increase in the content of hydrocarbon gas other than methane, and conversely, the sound speed decreases. Therefore, by utilizing this phenomenon, the speed of sound of the gas to be measured can be measured, and the calorific value, specific gravity, and the like can be obtained from this.
For example, taking the calorific value as an example, as shown in FIG. 4, in natural gas, for example, the sound velocity and the calorific value can be expressed by a primary or secondary correlation equation. Therefore, when measuring the calorific value, the calorific value is calculated from the speed of sound according to a relation index determined in advance. This relationship is also satisfied with respect to specific gravity. Further, since the Wobbe index is an index related to the calorific value and the specific gravity, such a relationship holds. As a result, it has become possible to satisfactorily measure the physical properties of this kind of mixed gas, which is usefully used as city gas today.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically illustrates a configuration in which a gas measuring device 1 of the present application is provided in a gas production facility 2. The gas production facility 2 includes a supply flow path 5 having an LNG tank 3 and an LNG vaporizer 4 on the upstream side,
An adjustment gas addition mechanism 6 for adding a calorie adjustment petroleum gas to the supply flow path 5, and basic data for measuring gas physical quantity of a product gas provided downstream of the adjustment gas addition mechanism 6. Is provided. The measuring section 7 is a portion where a measuring pipe 70 provided in the gas measuring device 1 is provided.
Through a pair of branch pipes 71 (see FIG. 2), the product gas is introduced and extracted. Here, a structure in which the product gas flows in the tube axis direction (predetermined direction) in the measurement tube 70 is adopted. This product gas is the measurement target gas to be measured by the gas measurement device 1 of the present application.

In the gas production facility 2, the measuring unit 7
The amount of physical properties of the product gas is determined based on the measurement information obtained in the above step. For example, from the relationship between the calorific value and the target calorific value that is the calorific value required for the product gas, the adjustment gas addition mechanism 6 , And an adjustment control command is generated. In the gas measurement device 1 of the present application, it is possible to measure the calorific value, specific gravity, Wobbe index, combustion rate index, and combustion characteristics of the measurement target gas as the physical properties of the measurement target. Since the calorific value is mainly used, the calorific value will be mainly described.

Now, in order to enable the above control, a natural gas flow rate measurement for measuring the flow rate of natural gas in the above-mentioned supply flow path 5 upstream of the junction 8 of the adjusting gas addition mechanism 6 is described. A vessel 9 is provided. On the other hand, the above-described adjusting gas addition mechanism 6 includes an addition flow path 12 provided with an LPG tank 10 and an LPG vaporizer 11 on the upstream side, and a flow control valve 13 and a petroleum gas flow rate. A measuring device 14 is provided. In the facility 2, the flow rate of the natural gas and the flow rate of the petroleum gas with respect to the natural gas are constantly monitored, and it is possible to detect the quantity ratio of the natural gas and the petroleum gas that is sent out in a mixed state downstream of the supply flow path. When it is necessary to control the calorific value of the product gas as in the present application, this quantity ratio becomes a problem.
By appropriately adjusting the opening degree of No. 3, it is possible to adjust the flow rate ratio between the two (and, consequently, the calorific value).

The gas production facility 2 is provided with a supply passage 5 through which a base gas raw material containing methane as a main component (natural gas in this example) flows.
An adjusting gas addition mechanism 6 for adding a calorie adjusting gas raw material (in this example, petroleum gas) having a larger calorific value than methane while adjusting the addition amount is provided to obtain a calorie-adjusted product gas. . Further, a heat generation amount control device 100 for the adjustment gas addition mechanism 6 is provided. As shown in FIGS. 1 and 2, the ultrasonic flowmeter 15, the thermometer 16a, and the pressure gauge 16b provided in the measuring unit 7 and the means for generating the adjustment control command in accordance with the measurement information from these instruments. It is composed of This means is constructed using a microcomputer, a semiconductor memory, and the like as main devices. Briefly describing this means, FIG.
As shown in the figure, the storage unit 17a, the index generation unit 17b,
Sound velocity measuring means 19 having the ultrasonic velocity meter 15 and sound velocity deriving means 18, calorific value deriving means 20 a, specific gravity deriving means 20 b, Wobbe index deriving means 20 c, burning velocity index deriving means 20 d, combustion characteristic deriving means 20 e, adjustment Control command generation means 21 is provided. Here, the storage unit 17
a is information necessary for deriving the calorific value and specific gravity, and a compatibility diagram required for deriving the combustion characteristics (however, the stored state is configured so that the combustion characteristics can be specified by designating the Wobbe index and the combustion speed index). ) Is stored. The index generating means 17b generates a sound speed-heating amount relation index and a sound speed-specific gravity relation index from the information on the heat value and the specific gravity stored in the storage means 17a. The sound speed measuring means 19 is for obtaining the sound speed of the product gas. The calorific value deriving means 20a is for deriving a calorific value from the sound velocity obtained by the sound velocity measuring means 19, and the specific gravity deriving means 20b
Is for deriving a specific gravity from the sound velocity obtained by the sound velocity measuring means 19, and the Wobbe index deriving means 20c is a calorific value derived by the calorific value deriving means 20a and a specific gravity derived by the specific gravity deriving means 20c. From
It derives the Wobbe index. Further, the burning rate index deriving means 20d calculates the specific gravity obtained from the specific gravity deriving means 20b based on the content of hydrogen, carbon monoxide, hydrocarbons other than methane, and oxygen in the gas to be measured which are separately detected. This is used to derive the combustion rate index of the gas to be measured. Further, the combustion characteristic deriving means 20e
Is configured to derive a combustion estimation state of the combustible gas based on the compatibility diagram stored in the storage unit 17a based on the Wobbe index and the combustion speed index of the combustible gas, The Wobbe index obtained by the Wobbe index derivation means 20c shown above and the combustion rate index derivation means 20
The estimated combustion state of the gas to be measured is derived from the combustion rate index obtained from d. Further, the adjustment control command generation means 21 generates an adjustment control command from the obtained heat value. The gas measurement device 1 of the present application includes:
All means except the adjustment control command generating means 21 are provided. Therefore, the gas production facility 2 is configured to give feedback on the calorific value, and can maintain good calorific value quality of the product gas. here,
The heating value control is a continuous control of online and on-time.

Hereinafter, the configuration and operation of each means will be described in more detail. As described above, the storage means 17a stores the sound speed-heat value obtained from the relationship between the sound speed, heat value, and specific gravity of each of a plurality of standard gases in which the base gas and the calorific value adjusting gas are mixed at different ratios. Relationship indicators,
Information that can derive a sound speed-specific gravity relationship index is stored.
FIG. 4 shows an example of such a sound speed-calorific value relation index. In the figure, a correlation line (represented by a first-order correlation expression and a second-order correlation expression) indicated by a solid line and a broken line corresponds to this index. The sound speed-calorific value relation index is stored in the storage unit 17.
It is automatically generated by the index generation means 17b based on the measurement result of the temperature and pressure of the product gas from the information stored in a. These temperature and pressure information can be obtained from the thermometer 16a and the pressure gauge 16b. Similarly, the sound speed-calorific value relation index is automatically generated by the index generation means 17b. For this purpose, the aforementioned storage means 17 stores a sound velocity-temperature-pressure relationship index (shown in FIG. 3) for a plurality of standard gases whose calorific value and specific gravity are known in advance. From the plurality of sound velocity-temperature-pressure relation indices according to the temperature and pressure of the product gas, the index generation means 17b calculates the relation index between the sound velocity and the calorific value (the sound velocity-calorific value relation index in FIG. 4). Is automatically generated. That is, the sound speed with respect to the standard gas having each calorific value is obtained from the sound speed-temperature-pressure relationship panel shown in FIG. 3, and the sound speed and the heat speed are arranged as shown in FIG. Generated as a quantity-related index. By using this index, for example, when the sound speed is determined, the calorific value of the gas can be derived from the sound speed as shown by the dashed line with the arrow in FIG. Such processing is
Similar processing is possible for the specific gravity, and is configured to perform the same processing.

The sound velocity measuring means 19 includes the above-described ultrasonic velocity meter 15 and the sound velocity deriving means 18. From the ultrasonic flow meter 15, the flow velocity of the product gas flowing in the measurement tube 70 is obtained, and a pair of propagation times T21 and T12 are obtained in measuring the flow velocity. Ultrasonic current meter 1
2 will be described with reference to FIG. 2. The measuring device 5 includes a measuring tube 70 on a straight pipe through which a gas to be measured flows in the direction of the tube axis. A pair of ultrasonic transceivers 15a are provided at opposite ends so that the detection units face each other. Here, since the pair of ultrasonic transceivers 15a are disposed at different positions in the axis Z direction of the flow path, the ultrasonic waves passing between the two are affected by the flow velocity v and propagate from the upstream side to the downstream side. The propagation time of the ultrasonic wave is accelerated, and vice versa. The configuration for introducing the gas to be measured into the measuring pipe 70 will be described. The branch pipe 71 is independently connected to an inlet 72 and an outlet 73 provided on the side wall of the measuring pipe 70. The measurement target gas flowing from the port 72 flows through the measurement pipe 70 and returns to the main pipe side via the outlet port 73. In the current meter 15, one ultrasonic transceiver 15a is connected to the other ultrasonic transceiver 1a.
5a captures the propagation time of the ultrasonic wave propagating in the flow of the product gas in two directions (the ultrasonic wave propagation time T21 from the upstream to the downstream, and the ultrasonic wave propagating in the opposite direction). , The flow velocity of the product gas is measured from the pair of obtained propagation times. Therefore, in the ultrasonic current meter 15, as the measurement information, the flow velocity v,
The pair of propagation times T21 and T12 are obtained.

The above-mentioned sound velocity deriving means 18 is configured to be able to derive the sound velocity of the product gas from a pair of measured propagation times of the product gas. In this derivation process, the sound velocity C is obtained from the pair of propagation times T21 and T12.
This structure will be described.
Since the positional relationship between the pair of ultrasonic transmitter / receivers 15a provided in the pair is fixed, the propagation times T12 and T21 that propagate between the transmitter and the receiver can be described as shown in FIG. Here, L is half the distance of the propagation path shown in FIG. 2, C is the speed of sound, and v is the flow velocity of the product gas.

[0021]

(Equation 1)

Since the equations 1 and 2 are simultaneous equations, the sound velocity C and the flow velocity v can be obtained from the pair of propagation times T12 and T21 as shown in the equations 3 and 4.
That is, the above-described sound velocity deriving means obtains the sound velocity C from the pair of propagation times T12 and T21 by performing the processing of Expression 3.

[0023]

(Equation 2)

Next, the role of the calorific value deriving means 20 will be described. As shown by an alternate long and short dash line with an arrow in FIG.
From the sound speed of the product gas obtained by the sound speed measuring means 20, the calorific value of the product gas is obtained based on a sound speed-calorific value correlation index automatically generated from the information stored in the storage means 17.

The above description is mainly concerned with the calorific value. Hereinafter, the specific gravity, the Wobbe index, the burning speed index, and the burning characteristics will be described. Instead of the above-described sound velocity-heat generation amount relation index, the sound velocity-specific gravity relation index can be similarly obtained by replacing the heat generation amount with the specific gravity. In other words, the storage means 17a stores sound velocity-temperature-pressure relation indexes for a plurality of standard gases whose specific gravities are known in advance, and the index generation means 17b calculates
In accordance with the temperature and pressure of the product gas, a relationship index between the sound speed and the specific gravity in this state is automatically generated from a plurality of sound speed-temperature-pressure relationship indicators. Then, the specific gravity deriving means 20b described above can calculate the specific gravity of the product gas from the sound velocity of the product gas separately obtained by the sound velocity measuring means 20, based on the sound velocity-specific gravity correlation index. In this way, the specific gravity of the on-time product gas can be measured.

Further, when the calorific value and specific gravity of the product gas are determined, the Wobbe index of the product gas (gas to be measured) is determined by using these physical properties and dividing the calorific value by the square root of the specific gravity. be able to. This operation derivation is
This is performed by the Wobbe index deriving means 20c. That is, the Wobbe index of the gas to be measured is determined based on the calorific value and the specific gravity obtained from each of the calorific value deriving means 20a and the specific gravity deriving means 20b.

The calorific value of the product gas thus obtained is compared with the target calorific value of the product gas, and the above-described adjustment control command is generated. The adjustment control command generation means 21 plays the role of this generation. On the other hand, the obtained physical property values are output as needed.

The structure relating to the derivation of the Wobbe index has been described above. The derivation of the combustion speed index and the combustion characteristics will be described below. The apparatus is provided with a content measuring means 74 for measuring the contents of hydrogen, carbon monoxide, hydrocarbons other than methane, and oxygen in the gas to be measured. here,
This means includes a sensor 74a capable of detecting each gas component.
And a converter 74b for converting the output of the sensor 74a into a content rate. Here, gas chromatography or the like is used as a sensor for detecting hydrocarbons other than methane. The output from the converter 74b is sent to the combustion rate index deriving means 20d for use. That is, the burning rate index deriving means 20d derives a burning rate index from the content rate measured by the content rate measuring means 71 and the specific gravity obtained from the specific gravity deriving means 20b. Here, the derivation formula follows the formula described in the section of the operation and effect. With the above configuration, the burning rate index of the gas to be measured can be obtained by the burning rate index deriving means 20d.

Next, the configuration of the combustion characteristic deriving means 20e will be described. The role of the compatibility diagram as shown in FIG. 6 is as described above. The compatibility diagram (corresponding data information, which is data configured to output a corresponding combustion characteristic by specifying the Wobbe index and the combustion rate index) is stored in the storage unit 17a as described above. Have been. Therefore, the combustion characteristic deriving means 20e determines the estimated combustion state of the combustible gas in accordance with the data stored in the storage means 17a in a state where these are specified based on the Wobbe index and the combustion rate index of the combustible gas. A configuration that can be derived is employed. Then, the Wobbe index obtained by the Wobbe index derivation unit 20c described above and the combustion speed index derivation unit 20 similarly described above.
The combustion characteristic deriving means 20e derives the estimated combustion state of the measurement target gas from the combustion rate index obtained from d. As a result, for example, the combustion characteristics of the gas to be measured can be obtained in real time. Here, the output combustion characteristic or combustion estimation state is a suitable combustion state indicating that the engine is in the compatible area, an incomplete combustion state indicating that the engine is in the incomplete combustion area, and a lift indicating that the engine is in the lift limit area. There are a limit state, a back limit state indicating that the vehicle is in the back limit area, and the like.

The basic configuration of the gas production facility 2 has been described above.

Accordingly, the calorific value measurement and calorific value control of the facility 2 are performed by controlling the sonic velocity, which is the relationship between the sonic velocity of each of a plurality of standard gases in which the base gas and the calorific value adjusting gas are mixed at different ratios, and the calorific value. A calorific value-related index is determined in advance, the sound velocity of the product gas is determined, and the calorific value of the product gas is determined from the determined sound velocity of the product gas (gas to be measured) based on the sound velocity-calorific value relation index. Based on the difference between the calorific value of the product gas thus obtained and the target calorific value, the amount of the calorie-adjusting gas material added to the base gas material is controlled. In addition, the gas measuring device 1 to which the present invention is directed can be applied to the calorie-adjusted product gas manufactured with the calorific value adjustment as described above, and can also control the calorific value by bypassing the adjusting gas addition mechanism 6. Needless to say, it can also be used for measuring the calorific value of the production gas in the production facility for producing the unheated gas without performing the above.

In the following, experiments and actual measurement results conducted by the inventors when adopting the measurement method of the present invention will be described. 1. Sound velocity-temperature-pressure relation index (table) This index is a relation index as shown in FIG. 3, and in order to obtain this relation index, nine kinds of heat values and specific gravities are used in principle as parameters. Was used as a standard gas. Table 1 shows the composition (%), calorific value and specific gravity of these standard gases.

[0033]

[Table 1]

These standard gases contain 80% as their main component.
% Of methane, and is a mixed gas obtained by adding and mixing a calorific value adjusting gas (hydrocarbon gas having 2 or more carbon atoms) to the base gas (methane) to adjust the calorific value. The sound velocity in a predetermined state (temperature / pressure state) can be measured using these mixed gases. For each of the above standard gases, four states (5, 15, 25,
35 ° C), and 4 states (10, 20, 30,
40 kgf / cm ² ) for each state (16 states)
I asked for the speed of sound. As shown in FIG. 3 and each table,
The speed of sound could be expressed by a linear relation of temperature with pressure as a parameter. Therefore, as shown in Table 2 below, the coefficients a and b of the linear relationship between the sound speed and the temperature were obtained for each standard gas and each pressure, and the information was stored in the storage means 17a described above. Therefore, the storage means 17
The relation index corresponding to FIG. 3 is stored and stored in “a”, and using this index, a sound velocity-calorific value relation index and a sound velocity-specific gravity relation index can be derived.

[0035]

[Table 2]

2. Sound velocity-calorific value relation index (table) This index is automatically generated by the index generation means 17b described above. In this process, a specific temperature / pressure is specified in the sound velocity-temperature-pressure relation index (table) obtained as described above. And
Recall the speed of sound from each different table corresponding to each standard gas with a different calorific value. Then, across each table in FIG. 3 (in the direction in which the tables overlap), a specific temperature
By reading the speed of sound at the pressure, the related index of FIG. 4 is obtained. However, in the figure, the vertical axis and the horizontal axis are reversed. In this manner, the correlation line between the sound speed and the heat value (FIG. 4)
By obtaining the solid line (first-order correlation equation) and the broken line (second-order correlation equation), the relationship index between the two in a specific temperature and pressure state can be obtained.

Using this sound speed-calorific value relation index,
If the temperature, pressure, and sound speed of the product gas are known, the calorific value of the gas can be obtained. The error of the calorific value obtained by such a method is as follows.
cal / Nm ³ , 15 kcal / N
m ^3, which is equivalent to or better than the conventional method using a hydrometer.

3. Sound velocity-specific gravity relation index (table) This index is also automatically generated by the index generation means 17b described above. In this process, a specific temperature / pressure is designated in the sound velocity-temperature-pressure relation index (table) obtained in the same manner as described above. Then, the speed of sound is called from each of the different tables corresponding to each standard gas having a different specific gravity. By reading the sound speed at a specific temperature and pressure across each table in FIG. 3 (in the direction in which the tables overlap), a specific gravity-related index (FIG. 5) corresponding to FIG.
Shown below) can be obtained. In this way, by obtaining a correlation line between the sound speed and the specific gravity, a specific temperature / specific gravity can be obtained.
An index of the relationship between the two in the pressure state is obtained.

Therefore, if the temperature, pressure, and sound speed of the product gas are known by using the sound speed-specific gravity relationship index, the specific gravity of the gas can be obtained. The error of the specific gravity obtained by such a method is that the specific gravity is 0.555 to 0.713.
(Unit: dimensionless) within the range of about ± 0.4 (unit:%), and can achieve the same or better accuracy than the conventional method using a hydrometer. Was.

Further, based on the specified calorific value and specific gravity, the Wobbe index, the burning rate index, and the combustion specification could be obtained. [Another Embodiment] (A) In the above embodiment, a sound velocity-heat generation amount relation index and a sound velocity-specific gravity relation index are automatically generated from a sound velocity-temperature-pressure relation index obtained in advance. However, a sound speed-calorific value relation index and a sound speed-specific gravity relation index corresponding to (temperature, pressure) may be stored, and these indexes may be used. (B) In the above embodiment, the base gas is a gas mainly composed of methane (eg, natural gas), and the calorific value adjusting gas is a gas having a larger calorific value (eg, petroleum gas).
However, such a gas type does not matter. Therefore, in this case, it is a matter of course that a gas containing methane as a main component and a hydrocarbon gas having more carbon atoms than methane can be used. Further, as described above, it is possible to measure a product gas that has undergone calorific value adjustment and a so-called unheated gas that does not have calorific value adjustment.

[Brief description of the drawings]

FIG. 1 is a block diagram of a gas production facility equipped with a gas measurement device of the present application.

FIG. 2 is a diagram showing a detailed structure of a measuring unit.

FIG. 3 is a diagram showing a pressure-temperature-sound speed relationship index using a heat value as a parameter;

FIG. 4 is a diagram showing a sound speed-heat generation amount relationship index when a heat generation amount is derived from a sound speed.

FIG. 5 is a diagram showing a sound speed-calorific value relation index when a specific gravity is derived from a sound speed.

FIG. 6 is a diagram showing a compatibility diagram;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat generation amount control device 2 Gas production equipment 15 Ultrasonic flowmeter 15a Ultrasonic transceiver 17a Storage means 17b Index generation means 18 Sound velocity derivation means 19 Sound velocity measurement means 20a Heat generation amount derivation means 20b Specific gravity derivation means 20c Wobbe index derivation means 20d Combustion Speed index deriving means 20e Combustion characteristic deriving means

Claims (8)

[Claims] 1. A measuring part into which a gas to be measured is introduced and flowing in a predetermined direction, and a detecting part of a pair of ultrasonic transceivers is provided at a predetermined part of the measuring part so as to face each other. A sound velocity derivation for capturing a propagation time of an ultrasonic wave propagating in the flow of the gas to be measured from the ultrasonic transceiver to the other ultrasonic transceiver in two directions, and obtaining a sound velocity of the gas to be measured from a pair of obtained propagation times. With means,
A gas property measuring device comprising: a specific gravity deriving unit that obtains a specific gravity of the gas to be measured from a sound velocity obtained by the sound speed deriving unit; and an output unit that outputs the obtained specific gravity. And a calorific value deriving means for obtaining a calorific value of the gas to be measured from the sound velocity obtained from the sound speed deriving means, and a calorific value obtained from the calorific value deriving means and a specific gravity obtained from the specific gravity deriving means. 2. The gas property measuring device according to claim 1, further comprising: a Wobbe index deriving unit that obtains a Wobbe index of the gas to be measured, and wherein the output unit also outputs the Wobbe index obtained. 3. A content measuring means for measuring the content of hydrogen, carbon monoxide, hydrocarbons other than methane, and oxygen in the gas to be measured, and a content measured by the content measuring means. 3. A combustion rate index deriving means for deriving a burning rate index of the gas to be measured from the specific gravity obtained from the specific gravity deriving means, and the output means also outputs the calculated burning rate index. Gas property measurement device. 4. A combustion characteristic deriving means for deriving a combustion estimation state of the combustible gas based on a Wobbe index and a burning rate index of the combustible gas, wherein the Wobbe index obtained by the Wobbe index deriving means; 4. The combustion characteristic deriving means derives a combustion estimation state of the gas to be measured from a combustion velocity index obtained by the combustion velocity index deriving means, and the output means also outputs the combustion estimation state obtained by the combustion characteristic index. The gas physical property measuring device according to the above. 5. The gas physical property measuring apparatus according to claim 1, wherein the gas to be measured contains methane as a main component and a hydrocarbon gas other than methane. 6. A pair of the propagation times in which the ultrasonic waves propagate along the flow direction of the gas to be measured are captured in a direction from the upstream side to the downstream side and in a two-way direction from the downstream side to the upstream side. The sound velocity of the gas to be measured is determined from the propagation time of the gas, the specific gravity and the calorific value of the gas to be measured are determined from the determined sound speed, and the Wobbe index of the gas to be measured is determined from the calorific value and the specific gravity determined. Method. 7. A method for measuring the contents of hydrogen, carbon monoxide, hydrocarbons other than methane, and oxygen in the gas to be measured, and measuring the content and the specific gravity of the gas to be measured, 7. The method for measuring gas properties according to claim 6, wherein a combustion rate index of the gas to be measured is obtained. 8. A gas combustion state estimation method for obtaining a combustion estimation state of the measurement target gas from a Wobbe index of the measurement target gas and a combustion rate index obtained by the gas physical property measurement method according to claim 7.