JPH08285766A - Method and apparatus for measuring concentration of odorant - Google Patents

Abstract

PURPOSE: To measure the concentration of odorant in real time base by irradiating an odorized gas with detection ultraviolet rays and then determining absorbance of the odorized gas based on the transmitted ultraviolet rays. CONSTITUTION: At a section 1a for detecting the absorbance of odorized gas, a channel 20 for passing an odorized gas mixed with odorant and unodored gas is irradiated 5 with detection ultraviolet rays soluble to the odorant but insoluble to the unodored gas and the detection ultraviolet rays, transmitted through the odorized gas, is received 9. A section 1b for detecting the absorbance of unodored gas is constituted similarly to the detecting section 1a. The gas flowing through each part is irradiated with the detection ultraviolet rays at the detecting sections 1b, 1a and the intensity of irradiation is measured along with the intensity of received light. Subsequently, the absorbance is determined for the unodored gas and odorized gas according to the relationship between the intensity of irradiation and the intensity of received light at the detecting sections 1a, 1b. Finally, an analyzing/displaying section 1c subtracts the absorbance of odorized gas from that of unodored gas thus determining the concentration of odorant based on a prestored index relating to the absorbance of odorized gas.

Description

Detailed Description of the Invention

[0001]

[Industrial application] For city gas, odorants such as tertiary butyl mercaptan (hereinafter abbreviated as TBM), dimethyl sulfide (hereinafter abbreviated as DMS), and tetrahydrothiophene (hereinafter abbreviated as THT) Is added and used. The present application relates to a technique for measuring the concentration of the odorant in city gas, propane gas, etc. to which such an odorant is added and used.

[0002]

^2. Description of the Related Art Conventionally, when measuring the odorant concentration, sample gas is decompressed and sampled from a delivery pipe (a high pressure gas supply pipe of about 10 to 100 kg / cm ² ) and installed in an analysis room away from the site. The odorant concentration is determined using a gas chromatograph with FPD.

[0003]

Therefore, the above-mentioned prior art has various problems as described below. (1) Since vacuum sampling is required, a dilution step for this is required, and it is necessary to measure the concentration of unodorized gas (for example, 13A which is a kind of city gas) and the odorant component while separating the components. Therefore, it takes time to measure. Therefore, for example, it is practically impossible to monitor the odorant concentration in real time at a specific portion of the high-pressure pipe. (2) The measurement accuracy is not sufficient because it involves dilution. (3) The sample in a depressurized state after being sampled is discarded without being used. An object of the present invention is to obtain a measuring method and a measuring device for the odorant concentration that can solve the above-mentioned various problems.

[0004]

According to the first aspect of the present invention, there is provided a post-odorizing gas comprising an unodorized gas containing hydrocarbon gas as a main component and an odorant added thereto. The characteristic means of the method for measuring the odorant concentration is to irradiate the post-odor gas with ultraviolet rays for detection, which are easily absorbed by the odorant and difficult to be absorbed by unodorized gas, and pass through the post-odor gas. The first step of receiving the ultraviolet ray for detection received and obtaining the absorbance of the post-odor gas from the relationship between the irradiation intensity and the received intensity, and the absorbance of the post-odor gas obtained in the first step The second step is to determine the concentration of the odorant in the post-odor gas.
In the method for measuring the concentration of an odorant according to claim 1, when the odorant contains dimethyl sulfide (DMS), it is preferable to use the ultraviolet ray for detection including an ultraviolet ray having a wavelength of 195 nm or a wavelength of 202 nm. This is a characteristic means of the method for measuring the odorant concentration according to claim 2. The odorant concentration measuring method according to claim 1, wherein the odorant is tertiary butyl mercaptan (T
BM), the wavelength is 202 nm or the wavelength is 20
It is preferable to use the above-mentioned ultraviolet ray for detection, which includes an ultraviolet ray of 4 nm. This is a characteristic means of the method for measuring the odorant concentration according to claim 3. The method for measuring the concentration of an odorant according to claim 1, 2 or 3, further comprising a preliminary step of obtaining an unodorized gas absorbance of the detection ultraviolet ray by the unodorized gas before the odorization process, The absorbance of the unodorized gas is subtracted from the absorbance of the post-odorizing gas obtained in one step to obtain the odorant absorbance, and in the second step, the odorant absorbance is converted into the post-odorizing gas. It is preferable to determine the odorant concentration in the above. This is,
It is a characteristic means of the method for measuring the odorant concentration according to claim 4.

Further, the characteristic configuration of the odorant concentration measuring apparatus according to claim 5 for achieving the above object is that the odorant is added to an unodorized gas containing hydrocarbon as a main component. With respect to the post-odor gas passage through which the post-odor gas flows, in the post-odor gas passage, a detection ultraviolet ray that is easily absorbed by the odorant and is difficult to be absorbed by the unodorized gas is detected. UV irradiating means, and a light receiving means for receiving the detection ultraviolet rays that permeate the odorized gas, and the irradiation intensity of the detection ultraviolet rays in the detection ultraviolet irradiating means and the light receiving means From the received light intensity of the detection ultraviolet ray to be detected, it is provided with a post-odor gas absorbance derivation means for determining the absorbance of the post-odor gas, and the absorbance of the post-odor gas obtained by the post-odor gas absorbance derivation means. Use to obtain the concentration of the odorant Lies in the fact that with the odorant concentration deriving means that. The odorant concentration measuring apparatus according to claim 5, further comprising an unodorized gas absorbance derivation mechanism that obtains the absorbance of the unodorized gas before the odorization process with respect to the ultraviolet ray for detection. The means, from the absorbance of the gas after odorization obtained by the odorant gas absorbance derivation means, from the odorant absorbance obtained by subtracting the unodorized gas absorbance obtained by the unodorized gas absorbance derivation mechanism It is preferable to determine the concentration of the odorant. This is a characteristic configuration of the odorant concentration measuring apparatus according to claim 6. The actions and effects thereof are as follows.

[0006]

In the method for measuring the odorant concentration according to the first aspect, the so-called ultraviolet absorption method is adopted for measuring the odorant concentration. Here, when a gas obtained by mixing a gas containing a hydrocarbon as an unodorized gas as a main component and an odorant as described above is targeted as in the present application, it is absorbed by the unodorized gas. It is difficult, and the odorant has ultraviolet rays with a wavelength that is easily absorbed. Therefore, the ultraviolet ray having such characteristics is adopted as the detecting ultraviolet ray and used for the measurement. The ultraviolet ray for detection having such a specific wavelength is irradiated to the odorized gas to be measured. Then, the detection ultraviolet ray that has passed through the post-odor gas is received, and the absorbance of the post-odor gas is obtained from the relationship between the irradiation intensity and the received intensity. This step is the first step. This absorbance becomes proportional to the concentration of the odorant contained in the gas after odorization due to the characteristics of the wavelength of the ultraviolet ray for detection.
Therefore, in the second step, the odorant concentration is obtained from this absorbance. FIG. 2 shows the city gas (13A gas), which is an example of an unodorized gas, and the odorant DMS 45.
The absorbance of each wavelength of the odorized gas added with 8 ppm was shown. Solid lines in the figure show the absorbance distributions at the respective wavelengths. On the other hand, FIG. 3 shows the absorbance distribution at each wavelength in the case of city gas (13A gas) alone, which is an example of unodorized gas. By comparing FIG. 2 and FIG. 3, for example,
It is understood that the ultraviolet rays in the wavelength range of 190 nm to 220 nm are easily absorbed by the odorant and are hardly absorbed by the unodorized gas. Further, FIG. 4 shows the relationship between the concentration of the odorant in the above example and the absorbance of ultraviolet rays of a specific wavelength in FIG. In this example, ultraviolet rays for detection having wavelengths of 195 nm and 202 nm are adopted. As is clear from the figure, the odorant concentration and the absorbance are supposed to maintain a first-order approximation relationship, and the odorant concentration can be determined from this absorbance by determining the absorbance of the detection ultraviolet light. I understand. Here, the gas after odorization is in a high pressure state, and is suitable for real-time measurement at the site of the high-pressure city gas supply piping on site. In the odorant concentration measuring method according to claim 2, when DMS is used as the odorant, the ultraviolet ray for detection has a wavelength of 195 nm, 202
nm is used. As shown in FIG. 2, this odorant has high absorption of ultraviolet rays of this wavelength. Therefore, the obtained absorbance can be increased as an absolute amount, and accurate and favorable measurement can be performed. In the method for measuring the concentration of an odorant according to claim 3, T is used as the odorant.
Target BM. Wavelength of 202nm as ultraviolet ray for detection
When the odorant of 204 nm is used, as shown in FIG. 5, this odorant has a high degree of absorption of ultraviolet rays of this wavelength. Therefore, the obtained absorbance can be increased as an absolute amount, and accurate and favorable measurement can be performed. Similar to FIG. 2, FIG. 5 shows that TBM, which is an odorant, is added to city gas (13A gas), which is an example of an unodorized gas, by adding 44.
The absorbance of each wavelength of the odorized gas added with 4 ppm was shown. Solid lines in the figure show the absorbance distributions at the respective wavelengths. In the method for measuring the concentration of an odorant according to claim 4, when the second step in the method for measuring the concentration of an odorant according to claim 1 is performed, the odorant is simply determined from the absorbance of the gas after odorization. Without performing the processing for obtaining the concentration, the absorbance of the unodorized gas alone for the unodorized gas is determined through a preliminary step. Then, the absorbance of the unodorized gas is subtracted from the absorbance of the post-odorizing gas obtained in the first step to obtain the odorant absorbance due to only the odorant. Then, in the second step, the odorant concentration is obtained from the odorant absorbance. By doing so, it is possible to obtain an accurate odorant concentration that does not depend on the situation of unodorized gas.

The odorant concentration measuring device according to a fifth aspect of the invention is provided with an ultraviolet ray detecting means for detection, a light receiving means, a post-odor gas absorption derivation means, and an odorant concentration derivation means. Then, the odorized gas to be measured is irradiated with the detection ultraviolet light from the detection ultraviolet irradiation means. The ultraviolet ray for detection that has passed through the gas after the odor is received by the light receiving means. Here, the absorbance of the post-odorizing gas to be measured is obtained by the post-odorizing gas absorbance deriving means from the relationship between the irradiation intensity of the irradiation means and the received light intensity of the light received by the light receiving means. Then, the odorant concentration is derived by the odorant concentration deriving means from the absorbance of the post-odorizing gas.
That is, in this apparatus, the above-mentioned first step is carried out by providing the detecting ultraviolet ray irradiating means, the light receiving means, and the post-odor gas absorption derivation means, and the second step is carried out by the odorant concentration derivation means. Furthermore, in the odorant concentration measuring device according to claim 6, the odorant concentration measuring method according to claim 4 is implemented. That is, the unodorized gas absorbance, which is the absorbance of the detection ultraviolet light in the unodorized gas alone state before the odorization process, is obtained by the unodorized gas absorbance derivation mechanism. Then, by subtracting the unodorized gas absorbance that depends only on this unodorized gas from the after-odorized gas absorbance that is known for the after-odorized gas, the odor that is the absorbance due to the odorant is added. The odorant absorbance is determined, and the odorant concentration is determined by the odorant concentration deriving means from the odorant absorbance. In the case of this configuration, the concentration of the odorant can be accurately obtained based on the information obtained by removing the influence of the absorption by the unodorized gas that may be considered as noise. Furthermore, in the measurement, it is not necessary to separate the unodorized gas and the odorant by, for example, a gas chromatographic method and measure the concentration.

[0008]

Therefore, by adopting the method for measuring the odorant concentration according to claim 1, for example, in the LNG vaporization plant, the odorant concentration can be obtained even in the supply pipe where the gas is in a high pressure state. Can be measured on a real-time basis. Further, in the present application, since the ultraviolet ray absorption by the gas is used as the measurement principle, it is possible to perform accurate continuous measurement in a short time, and it is possible to easily control the odorant concentration. Furthermore, in the measurement, it is not necessary to degas the sample gas for measurement and depressurize it for use in the measurement, so there is no need to dispose of the sample gas. Can be used. In the method for measuring the odorant concentration according to the second aspect, the DMS concentration in the post-odorizing gas to which DMS is added can be accurately and promptly measured. In the method for measuring the odorant concentration according to claim 3, TB in the odorized gas to which TBM is added
It has become possible to accurately and quickly determine the M concentration. In the method for measuring the concentration of an odorant according to claim 4, it is possible to accurately measure the concentration of the odorant by removing the absorption by the unodorized gas which is a noise component which is a problem in the measurement of the odorant concentration. It became so. Since the odorant concentration measuring device according to claim 5 realizes the measuring method according to claim 1 as a device, almost the same effect can be obtained as a device. Since the odorant concentration measuring device according to claim 6 implements the measuring method according to claim 4 in a device-like manner, it is possible to obtain substantially the same effect as the device.

[0009]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows a usage situation of the odorant concentration measuring device 1 of the present application. This figure shows the gas supply pipe 2 in a high pressure state in a city gas manufacturing plant that manufactures city gas (specifically, 13A gas) that is unodorized gas supplied to urban areas, An odorant addition device 3 is provided. Therefore, the odorant is added from the odorant addition device 3 into the gas supply pipe 2, and the gas becomes odorant gas and odorless gas after odorization. The pipe through which the post-odorizing gas flows is referred to as the post-odorizing gas passage 20. Explaining the composition of 13A gas, it is 88% methane, 6% ethane, 4% propane.
%, Butane is a gas mixed at a volume ratio of about 2%,
It is configured by mixing a plurality of types of hydrocarbon gas. Further, TBM, DMS, THT and the like are known as odorants, and the case shown in the same figure shows the case where the above two are added together. On the other hand, the gas supply pipe 2 has 10
The pressure is set to about 100 kg / cm ^{2, and} the downstream side of the gas supply pipe 2 is connected to the city gas consumption area 4. Therefore, the sample gas required for measuring the concentration of the odorant is also sent to the consuming place 4 as it is.

The configuration of the odorant concentration measuring device 1 of the present application installed in the portion shown in the figure will be described below. This odorant concentration measuring device 1 measures the concentration of the odorant added to the post-odor odorant gas under high pressure flowing in the gas supply pipe 2, and the measured concentration exceeds the upper and lower control ranges. In this case, it plays a role of issuing an alarm and controlling the addition amount of the odorant in the adding device 3 in an appropriate direction. The odorant concentration measuring device 1 includes a post-odor gas absorption amount detection unit 1a for detecting the absorption amount of the detection ultraviolet ray in the post-odor gas, and a detection ultraviolet ray of the unodorized gas alone before the odor. Unodorized gas absorption amount detection unit 1b for detecting absorption amount
And an analysis / display unit 1c for determining the concentration of the odorant by determining the absorbance of each gas from the amount of light detected by the detection units 1a and 1b and the absorbance due to the odorant. . Furthermore, it also has an alarm generation mechanism 1d and a control mechanism 1e for the addition device 3.

The after-odor gas absorption amount detecting section 1a is absorbed by the odorant in the after-odor gas passage 20 in which the after-odor gas mixed with the odorant and the unodorized gas flows. It is provided with a detecting ultraviolet ray irradiating means for irradiating the detecting ultraviolet ray which is easy to be absorbed by the unodorized gas and a light receiving means for receiving the detecting ultraviolet ray passing through the post-odorizing gas. This detection ultraviolet irradiation means irradiates the ultraviolet irradiation device 5 and the ultraviolet ray having a specific wavelength (this ultraviolet ray is referred to as detection ultraviolet ray) among the ultraviolet rays emitted from the ultraviolet irradiation device 5 to the post-odor gas. Is provided with a wavelength switching filter 6 and a transmission window 7 that allows the detection ultraviolet light to pass through and enter the pipe specific portion. The light receiving means is for receiving the above-mentioned ultraviolet rays for detection which are transmitted through the gas after odorization, and is provided with a light receiving window 8 and a light receiving device 9 which are arranged so as to face the transmission window 7. Is configured. Then, the irradiation intensity and the received light intensity of the detection ultraviolet rays are configured to be measurable.

The unodorized gas absorption amount detection unit 1b described above is generally constructed in the same manner as the post-odorization gas absorption detection unit 1a. However, the target gas is unodorized gas before odorization. At this portion, of course, the detection ultraviolet ray of the wavelength which is irradiated to the post-odorizing gas absorbance detecting section 1a is also irradiated to the unodorized gas and received by the selection of the wavelength switching filter 6. It Then, the irradiation intensity and the received light intensity of the detection ultraviolet ray with respect to the unodorized gas are configured to be measurable.

The detection ultraviolet rays used have central wavelengths of 195 nm, 202 nm, and 204 nm, and the wavelength selection is performed by the wavelength switching filter 6. Further, its bandwidth is set to about 1 nm. The optical path length of the detecting ultraviolet ray at this part is 1
It is set to 0 to 20 cm.

The analysis / display unit 1c collects and analyzes information from the above units. This part 1c is composed of a computer 11 provided with a so-called display device 10 for detecting information from the post-odor odor gas absorption amount detection unit 1a and the unodorized gas absorption amount detection unit 1b, respectively. Determining the absorbance of the odorized gas and the unodorized gas from the irradiation intensity of the detection ultraviolet ray in the ultraviolet ray irradiation means and the received light intensity of the detection ultraviolet ray detected by the light receiving means Means and means for deriving unabsorbed odor gas absorbance are provided. Here, the absorbance A is defined by the following equation, where I ₀ is the irradiation intensity and I is the received light intensity. A = LOG ₁₀ (I ₀ / I)

A mechanism for obtaining the absorbance of the unodorized gas before the odorization process with respect to the ultraviolet rays for detection (composed of the unodorized gas absorbance detection unit 1b and the unodorized gas absorbance deriving means) is not attached. It is called the odor gas absorbance derivation mechanism.

Further, this analysis / display unit 1c is obtained by subtracting the unodorized gas absorbance determined by the unodorized gas absorbance derivation mechanism from the absorbance of the unodorized gas absorbance determined by the after-odorization gas absorbance derivation means. An odorant concentration deriving means for obtaining the concentration of the odorant from the absorbance of the odorant is provided. The odorant concentration deriving means stores a relational index (actually, a linear relational expression) between each odorant concentration and the absorbance with respect to the ultraviolet ray for detection as shown in FIG. 4 described above. Using this relationship, the odorant concentration can be determined from the absorbance. In this process, the absorbance of the post-odorizing gas from which the non-odorizing gas absorbance is subtracted is used. The derivation formula of each odorant concentration when two types of odorants are mixed together is shown below.

[0017]

[Equation 1] Here, in this embodiment, as a combination of λ1 and λ2, a combination of (195 nm, 202 nm),
Alternatively, a combination of (202 nm, 204 nm) is used.

The operation of the device 1 will be described below together with the method for measuring the odorant concentration of the present application. The state in which the odorant is added by the above-described addition device 3 will be described below. Therefore, only the odorless gas is present on the upstream side of the position of the device 3, and the post-odorizing gas is on the downstream side. The aforementioned unodorized gas absorption amount detection unit 1b and post-odor gas absorption amount detection unit 1a
At, the ultraviolet rays for detection are radiated to the gas flowing through the respective parts, and the irradiation intensity and the received light intensity thereof are measured. Then, the absorbance of the unodorized gas and the absorbance of the post-odorized gas are obtained from the relationship between the irradiation intensity and the received light intensity at the respective portions 1a and 1b. Here, the step of obtaining the absorbance of the odorized gas is called the first step. Next, the absorbance of the unodorized gas is subtracted from the obtained absorbance of the post-odorizing gas to obtain the odorant absorbance. Then, based on this odorant absorbance, the odorant concentration is obtained from the above-described formula and the previously stored relational index as shown in FIG. here,
A second step is a step of obtaining the odorant concentration in the post-odor gas by using the absorbance of the post-odor gas obtained in the first step.
It is called a step and a preliminary step of obtaining the unodorized gas absorbance of the detection ultraviolet ray by the unodorized gas before the odorization process. In this way, the concentration of the odorant can be measured.

An experiment conducted by the inventor in order to verify the operation of the odorant concentration measuring method and the odorant concentration measuring apparatus 1 of the present application will be described below. 1 Concentration dependence of DMS absorption spectrum The results of this experiment are shown in FIG. 4 as described above. The absorption spectra of both 195 nm and 202 nm are DMS.
The absorbance is increased in proportion to the concentration of the above, and the absorbance at 195 nm is twice the absorbance at 202 nm. Thus, it was confirmed that the correlation between the absorbance and the concentration had a good proportional relationship. Therefore, D
When MS is included, wavelength 195 nm or wavelength 20
It will be appreciated that it is preferable to use detection UV radiation, which includes 2 nm UV radiation.

2 Concentration dependence of TBM absorption spectrum The result of this experiment is shown in FIG. 6 as described above. Since the absorbance is ½ of DMS 195 nm, there is a large variation at a concentration of about 10 ppm, but there is a proportional relationship between the concentration and the absorbance, and the concentration measurement can be applied. Therefore, when TBM is included in the odorant, it can be seen that it is preferable to use detection ultraviolet rays including ultraviolet rays having a wavelength of 202 nm or 204 nm.

3 Selection of Optical Path Length When DMS was used as the odorant and the unodorized gas was city gas (13A), the optical path length of the ultraviolet ray for detection was examined in the case of adopting the measuring method of the present application. . here,
The pressure of the gas after odorization was assumed to be 40 atm. The ultraviolet absorption rate depending on the DMS concentration under such a condition can be obtained as follows.

The absorbance of DMS (Y _DMS ) is based on the experimental value.

## EQU2 ## Y _DMS = P / 2 × 0.0025 × X × L / 10 where P: gas pressure (atmospheric pressure), X: DMS concentration (ppm), L:
Optical path length (cm) 13A absorption (Y _13A )

## EQU3 ## Y _13A = P / 2 × 0.0057 × L / 10. At this time, the ultraviolet absorption rate (A _13A ) of 13A gas to which no odorant is added is

## EQU4 ## A _13A = 1-10̂ (-Y _13A ). Next, when the odorant is added, the absorption at that time (Y _total ) is

[ _Formula 5] Y _total = Y _DMS + Y _{13 A} , and the absorption rate (A
_total ) is

## _EQU6 ## A _total = 1-10 ^ (-Y _total ). Therefore, the absorption rate of only the odorant (A _DMS ) is

## _EQU00007 ## A _DMS = A _total -A _13A = 10 ^ (-P / 2 * 0.0025 * X * L / 10) -10 ^ (-(P / 2 * 0.0025 * X * L / 10 + P / 2 * 0.0057 × L / 10)). Therefore, the absorption rate of only the odorant is L = 5, 10, 20, 40 (cm) under the condition of P = 40 (atmospheric pressure),
It can be determined for X = 0 to 10 (ppm).
The result is shown in FIG. As a result, when the optical path is long, the absorption by 13A is large, and the absorption becomes close to saturation after the addition of DMS, and the change in the absorptance due to the DMS concentration difference becomes small.
On the contrary, if the optical path length is short, the absorption by 13A is also small, so DM
Even if the S concentration increases, the absorption does not saturate, and the difference in absorption rate due to the change in DMS concentration increases. As described above, the optimum optical path length can be obtained according to the control range of the odorant concentration and the delivery gas pressure. As a result, as the optical path length, the change in absorption rate is large with respect to the change in odorant concentration.
It turns out that 20 cm is good. [Other Embodiment] Another embodiment of the present application will be described below. (A) In the above examples, mainly as an odorant,
The case of targeting DMS and TBM has been described,
The method of the present application is applicable even when THT is targeted. Furthermore, although the city gas (13A) is used as the unodorized gas in the above-described embodiment, the invention can be applied to a gas mixed with any hydrocarbon gas.
A hydrocarbon gas having a carbon number of 4 or less is used as the unodorized gas, and DMS, TB is used as the odorant.
When one or more kinds of odorants selected from M and THT are used, the wavelength band thereof is 190 n as ultraviolet rays for detection.
It is preferable to select one in the range of m to 220 nm. In this band, the absorption of ultraviolet rays for detection by unodorized gas is small and the absorption by odorant is large,
This is because the measurement can be performed accurately. (B) Further, in the above-mentioned examples, the absorbance of the gas after odorization is determined, the absorbance of the unodorized gas is determined, and the absorbance of the odorant as the difference between them is determined, and the odorant absorbance is calculated from this value. Although the concentration of the odorant is sought, the ultraviolet ray for detection used in the present application is basically difficult to be absorbed by the unodorized gas, so the absorbance of the gas after odorization is almost the same as that of the odorant concentration. Can be Therefore, it is also possible to employ a configuration in which the odorant concentration is directly obtained from the absorbance of the odorized gas without performing the above subtraction. In this case, the device configuration can be simplified and the cost can be reduced. Examples of this are wavelengths 195 nm and 202 nm for DMS.
Then, there can be mentioned a case where the detection ultraviolet ray having a bandwidth of 1 nm is adopted.
An example is the case where detection ultraviolet light having a bandwidth of 1 nm is adopted. When a wider bandwidth is used, it is preferable to use a structure in which the absorbances of the both are separated and detected, and it is preferable to use the configuration of the embodiment in terms of accuracy. (C) In the above-mentioned examples, the case where two kinds of odorants are added as odorants is shown, but in the case where only one kind is added, and when three or more kinds are added, Also, the concentration of each odorant can be obtained by a method equivalent to the above-described calculation formula by increasing the number of detection ultraviolet rays having different wavelengths corresponding to the number of odorants. (D) In the above-described embodiment, the mechanism for obtaining the absorbance of the unodorized gas before the odorization process with respect to the ultraviolet ray for detection (the unodorized gas absorbance derivation mechanism) is the unodorized gas absorption amount detection unit 1.
b) and the unodorized gas absorbance derivation means, the physical properties of such unodorized gas are relatively constant because they are strictly controlled when they are manufactured. Therefore,
For such a gas, the standard absorbance is stored in a storage device, and the absorbance value is appropriately called from this storage device and subtracted from the actual absorbance of the odorized gas. It is also possible. In this case, it is not necessary to provide the unodorized gas absorption amount detection unit 1b and the unodorized gas absorbance derivation means, and the device can be simplified. (E) When obtaining the concentration of the odorant from the odorant absorbance or the odorant gas absorbance, as described above, the relationship diagrams as shown in FIGS. 4 and 6 can be used. A relational table, an approximation formula such as a linear approximation formula, etc. can be used. In short, it suffices to obtain a known relational index in advance and, based on this, obtain the odorant concentration in the second step. (V) Furthermore, the odorant concentration measuring device of the present application can be provided in an arbitrary place in addition to being installed at a site under high pressure. Conventionally, the measurement of the odorant concentration has been performed under reduced pressure, and in this case, although the method of the present application can be adopted, the absorption is small and the detection is relatively difficult. When the gas after odorization is in a high pressure state, the absolute amount of the odorant is large, so that measurement in this state is easy on the contrary, and the system is suitable for site adaptation.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a usage state of an odorant concentration measuring device of the present application.

FIG. 2 is a diagram showing an absorption spectrum of an odorized gas to which DMS is added.

FIG. 3 is a diagram showing an absorption spectrum of 13A gas as an unodorized gas.

FIG. 4 is a diagram showing a relationship between odorant concentration and absorbance in DMS.

FIG. 5 is a diagram showing an absorption spectrum of gas after odorization to which TBM is added.

FIG. 6 is a diagram showing the relationship between odorant concentration and absorbance in TBM.

FIG. 7 is a diagram showing the relationship between DMS concentration and absorptance when the optical path length is changed.

[Explanation of symbols]

 20 Gas passage after odor

Claims (6)

[Claims] 1. A method for measuring the concentration of an odorant in a gas after odorization, which comprises adding an odorant to an unodorized gas containing hydrocarbon gas as a main component. Ultraviolet rays for detection that are easily absorbed and are not easily absorbed by the unodorized gas are irradiated to the post-odor gas, and the detection ultraviolet rays that pass through the post-odor gas are received, and the irradiation intensity and A first step of obtaining the absorbance of the post-odorizing gas from the relationship with the received light intensity; and the above-mentioned step in the post-odorizing gas using the absorbance of the post-odorizing gas obtained in the first step. A method for measuring an odorant concentration, comprising a second step of obtaining an odorant concentration. 2. The method for measuring the concentration of an odorant according to claim 1, wherein when the odorant contains dimethyl sulfide, the detection ultraviolet ray including the ultraviolet ray having a wavelength of 195 nm or a wavelength of 202 nm is used. 3. A wavelength of 202 nm or a wavelength of 20 when the odorant contains tertiary butyl mercaptan.
The method for measuring the concentration of an odorant according to claim 1, wherein the detection ultraviolet ray containing 4 nm ultraviolet ray is used. 4. A preliminary step for determining the absorbance of the unodorized gas of the detection ultraviolet ray by the unodorized gas before the odorization treatment is performed, wherein the unresolved gas is detected based on the absorbance of the unodorized gas obtained in the first step. The odorant absorbance is calculated by subtracting the odorant gas absorbance, and the odorant concentration in the post-odor gas is determined from the odorant absorbance in the second step. 3. The method for measuring the odorant concentration described in 3. 5. The post-odorizing gas flow path (20), in which the post-odorizing gas flows (20), wherein the post-odorizing gas has a structure in which an odorant is added to an unodorized gas containing hydrocarbon gas as a main component, In the flow path (20), a detection ultraviolet ray irradiating means for irradiating the detection ultraviolet ray which is easily absorbed by the odorant and is hard to be absorbed by the unodorized gas, and the odorous gas is transmitted. A light receiving unit for receiving the detection ultraviolet light, and from the irradiation intensity of the detection ultraviolet light in the detection ultraviolet irradiation unit and the light reception intensity of the detection ultraviolet light detected by the light receiving unit, after the odor An odorant concentration deriving means for determining the concentration of the odorant using the after-odor gas absorbance deriving means for obtaining the gas absorbance after the odor addition Odorant concentration measuring device equipped with. 6. An unodorized gas absorbance derivation mechanism for obtaining the absorbance of the unodorized gas before the odorization process to the detection ultraviolet rays, wherein the odorant concentration derivation means derives the post-odor gas absorbance. 6. The concentration of the odorant is determined from the odorant absorbance obtained by subtracting the unodorized gas absorbance determined by the unodorized gas absorbance derivation mechanism from the odorized gas absorbance determined by the means. The odorant concentration measuring device described.