JP2984915B2 - THT detecting agent in fuel gas, method for preparing the same, and THT detecting tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tetrahydrothiophene (C ₄ H ₈ S: Tetra Hydro T) contained as an odorant in fuel gas such as city gas and LP gas.
The present invention relates to a detection agent for simply, rapidly and accurately measuring (i.e., i.e., ITHENE, referred to as "THT" in this specification), a method for preparing the same, and a detection tube for THT in fuel gas using the detection agent.

[0002]

2. Description of the Related Art City gas, LP gas, and other fuel gas sent from a supply source to each customer by a conduit are passed through a pressure regulator, a gas meter, an on-off valve, and other devices installed in each pipe, and are then boiled. It is sent to various burning appliances such as burners, gas turbines or gas engines, gas stoves, gas ranges, gas cookers, instantaneous water heaters, baths, gas stoves, etc. for consumption. These fuel gases are rarely used continuously at all times, and are often used and consumed intermittently as needed.However, regardless of whether the gas is used or not, the piping and various equipment are used. In addition, it is necessary to always ensure that there is no leakage itself from various types of combustion equipment, and to ensure safety. Also, it is necessary to pay due attention to the danger caused by incomplete combustion in various types of combustion equipment.

[0003] Leakage of these gases can occur not only from the pipes, joints, gas meters, valves and the like, but also from the various types of combustion appliances themselves. Therefore, by detecting the presence or absence of the gas flow, and by measuring the flow rate when the gas is flowing, the presence or absence of gas leakage is monitored, and based on the monitoring result, the piping system, gas appliances, etc. Necessary repairs and management are performed to ensure safety, but odorous substances such as mercaptans are added to fuel gas as one of the methods to warn of the danger by immediately recognizing the gas leak. There is also adopted a method of easily and immediately detecting the leakage by odoring.

[0004] Such odorants for addition, that is, odorants, are usually THT, tertiary butyl mercaptan [TBM: C (CH ₃ ) ₃ -SH], dimethyl sulfide (DMS: H ₃ C-S). —CH ₃ ) and the like are used, and these are used alone or as a mixture of two or more components. Looking at the usage situation in Japan, THT is the largest, followed by TBM. In any case, the concentration of these odorants in city gas or other fuel gas depends on the purpose of their addition, ie, leakage. It is necessary to include more than the amount that can achieve the purpose of the alarm. Therefore, it is necessary to constantly monitor the presence and amount of the odorant.

For the measurement of the amount of odorant, at the laboratory level, a gas chromatograph (F) equipped with a flame photometric detector is generally used.
PD-GC) is used, but gas leakage
Since it can occur not only from a gas meter or valves and the like but also from these various types of combustion appliances, a means for performing simple, quick and accurate measurement in these fields is strongly desired. This spotting odor is TB
M is already in practical use, but when the odorant is THT, a portable gas chromatograph [J. High Resolution. Chromat.
ogr. 16,379 (1993)], a THT measuring instrument and a detection tube (Dragel, Germany), but each has its advantages and disadvantages, and at present there is no suitable one.

Among them, for example, the THT measuring apparatus is an apparatus based on the fundamental principle of measuring the ultraviolet absorption spectrum of a THT-iodine complex [Gas Quality, El.
Severer Science Publishers
B.V., Amstrdamp. 655 (1986),
JP-A-60-31056, JP-A-60-128334
issue〕. Although this device is small and light, it is slightly inferior in the measurement gas amount, measurement time, and the like as compared with the above-described case using the detection tube. Is composed of an H ₂ S removing agent and a detecting agent, and potassium permanganate supported on silica is used as the detecting agent. However, such a conventional detecting tube requires a long time (about 30 minutes), and the coloration is unclear, resulting in a large reading error.

As described above, the conventional THT detector tube not only requires a long time for the measurement, but also has an unclear color, large reading errors, and insufficient measurement results. The present inventors have repeatedly devised various experiments, experiments, and studies from various directions in order to solve such disadvantages and problems in the conventional detection tube, and found that the detection agent, that is, potassium permanganate supported on silica, was used. In the preparation process of the detection agent, (1) sufficient removal of impurities in the carrier,
(2) Predetermined considerations for supporting potassium permanganate on the carrier, and (3) Consideration of various points such as adding an appropriate amount of water after drying of the detection agent provides a short and clear presentation. The inventors have found that a detection agent showing a color can be obtained, and have reached the present invention.

[0008]

That is, the present invention provides:
Provide an excellent detection agent for quickly and accurately measuring the presence or absence or amount of THT added as an odorant to fuel gas such as city gas or LP gas, and a method for preparing the same.
Another object of the present invention is to provide a detection tube for THT measurement in fuel gas, which is simple, quick, accurate, and has a very small reading error by using the detection agent, which is far superior to conventional detection tubes. I do.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for preparing THA in a fuel gas comprising (A) a permanganate supported on a carrier.
A T-detecting agent, wherein the detecting agent is obtained by adding an aqueous solution of permanganate to the carrier sufficiently washed with pure water, then drying sufficiently, and then adding an appropriate amount of pure water to make the carrier water-containing. Providing a THT detecting agent in fuel gas, characterized in that:
(B) Further, the present invention provides a method for preparing T
A method for preparing an HT detecting agent, wherein the carrier is sufficiently washed with pure water, an aqueous solution of permanganate is added to the carrier, and the carrier is dried sufficiently, and then an appropriate amount of pure water is added to add water. The present invention provides a method for preparing a THT detector in a fuel gas.

(C) The present invention further provides a THT detecting tube in a fuel gas comprising a removing agent tube (pretreatment tube) and a THT detecting agent tube, wherein the THT detecting agent tube has silica therein. Or adding an aqueous solution of permanganate to a THT detector in a fuel gas comprising a permanganate supported on an alumina carrier, wherein the detector is sufficiently washed with pure water. A THT detecting agent tube filled with a THT detecting agent which is sufficiently dried and then added with an appropriate amount of pure water to contain water, thereby providing a THT detecting tube in fuel gas. is there.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The permanganate in the present invention is not limited as long as it is a permanganate which can be impregnated and supported as an aqueous solution on a carrier, but potassium permanganate is preferably used. . In addition, as the carrier in the present invention, an inorganic material such as silica or alumina which does not react with permanganate can be used, but silica is preferably used. Examples of these carriers include:
Specific examples include silica gel and alumina gel. In the present invention, these carriers are sufficiently washed with pure water. The term “sufficiently washed” as used herein means that these carriers are thoroughly washed with pure water (the same meaning throughout the present specification). ), High-purity ion-exchanged water or distilled water can be used as the pure water for washing and hydration.

In the present invention, the carrier is sufficiently washed with pure water as described above, and then the aqueous solution of permanganate is added to the washed carrier, followed by drying, and an appropriate amount of pure water is again added to the dried product. . In this case, the drying must be performed sufficiently, and therefore, vacuum drying is preferably applied. In the present invention, it is essential to dry after adding the aqueous solution of permanganate and before adding an appropriate amount of pure water. If the drying step is not performed, the desired THT detection is performed. No agent is obtained. In the present invention, after drying, an appropriate amount of pure water is added to uniformly impregnate. The amount of the impregnated water can be in the range of about 25 to 100%, preferably about 70 to 90%, more preferably 75 to 85%.
%, Particularly preferably in the range of 78 to 82%.

FIG. 1 is a view schematically showing a detecting agent tube filled with the above THT detecting agent. In FIG. 1, reference numeral 1 denotes a detecting agent tube, which may be made of a transparent plastic or glass, but is preferably formed of a transparent hollow glass tube. Reference numeral 2 denotes glass beads, and reference numerals 3 and 4 denote isolating agents. As the isolating agents 3 and 4, for example, alumina or silica is used. Reference numeral 5 denotes a layer filled with the detecting agent according to the present invention, 6 denotes a protective agent, and 7 denotes a packing. The packing 7 is not particularly limited as long as it does not affect the performance of the detection agent. For example, a polyethylene resin is used.

The protective agent 6 is filled and disposed to remove volatile components (mainly organic compounds) from the packing 7. For example, activated alumina or the like impregnated with an aqueous potassium permanganate solution is used. . In addition, it is necessary to seal both ends 8 and 9 of the detecting agent tube 1 airtight before use. However, in the case of a hollow glass tube, the seal is filled with the above-mentioned agents and then heated and melted. This can be done by putting on both ends 8, 9 at the time of use by cutting (cutting). The dimensions described in FIG.
It shows the approximate dimensions of each part, and is not limited to these. The same applies to the dimensions shown in FIG. 2 described below.

In order to detect THT in fuel gas quickly, with high accuracy, sharply and with a minimum reading error by using the above detecting agent tube, the fuel which adversely affects the THT detection is used. Interfering gas components in the gas, especially H
It is necessary to remove ₂ S in advance. FIG. 2 schematically shows a pretreatment tube (interference component removal tube) 10 for that purpose. As the material, glass or plastic can be used as in the case of the detection tube, but it is preferably formed of a hollow glass tube.

In FIG. 2, reference numeral 11 denotes a removing agent, and reference numerals 12 and 13 denote packings. The packings 12 and 13 are not particularly limited as long as they do not affect the performance of the removing agent and the detecting agent. A polyethylene resin or the like is used.
Further, both ends 14, 15 of the pretreatment tube 10 need to be air-tightly sealed before use, but when this is a hollow glass tube, it is heated and fused after filling the removing agent 11, At the time of use, both ends 14, 15 can be cut (cut) to be opened.

In using the detection agent tube 1 and the pretreatment tube 10, both ends of the detection agent tube 1 and both ends of the pretreatment tube 10 are cut and opened, and the pretreatment tube 10 is placed in front of the detection agent tube 1. Connected. FIG. 3 schematically shows the connection state.
2 are shown in a relatively reduced scale as compared with FIG. 2, and the same reference numerals are used for the same parts. Reference numeral 16 denotes a connection pipe that connects the left end of the detection agent pipe 1 and the right end of the pretreatment pipe 10, and is formed of a rubber pipe or the like. In use, the end 14 of the pretreatment tube 10 is connected to a gas source such as a test gas, and the gas sampling device is connected to the end 9 of the detection agent tube 1.
When the test gas is sucked from the gas sampling device, the test gas passes through the layer of the removing agent 11 and reaches the packed layer 5 of the detecting agent. By observing the change in the color layer, the presence or absence of THT in the test gas is determined. And / or the amount is measured.

The permanganate ion releases oxygen (oxidizes the substance to be oxidized), and is subjected to a reducing action by itself, and undergoes a change represented by the following equation. The change in color layer is due to the reduction effect of THT on permanganate ions of permanganate supported on an alumina or silica carrier, and according to the present invention, when THT is present (or when a predetermined amount or more is contained). ), MnO ₄ ^- ion (reddish purple: close to pink in combination with the white color of alumina or silica as a carrier)
In a short time such as 0 second, it is reduced to almost colorless Mn ²⁺ ions, and the color is sharply changed to white in combination with the color of alumina or silica as a carrier.

[Formula 1] MnO ₄ ^- [reddish purple] → MnO ₄ ^2- [green]
→ Mn ⁴⁺ (MnO ₂ ) [brown] → Mn ³⁺ [cherry blossom]
→ Mn ²⁺ (almost colorless)

In this regard, the above-mentioned detection tube is composed of an H ₂ S removing agent and a detecting agent, and uses potassium permanganate as the detecting agent. However, it actually takes about 30 minutes to change the color layer. (In the specification, it is about 15 minutes), and reading errors are large due to unclear coloration. On the other hand, according to the detection agent of the present invention, a sharp and clear change in the color layer as described above can be obtained in a short time such as 60 seconds.

As described above, in preparing the detecting agent of the present invention, at least (1) the carrier is sufficiently washed with pure water, and (2) after adding an aqueous solution of permanganate to the carrier, Three conditions are required and essential: sufficient drying, and (3) then adding an appropriate amount of pure water to contain water. In obtaining such excellent characteristics, which of (1) to (3) is the main cause, the causal relationship thereof is unknown, but it was carried out to obtain the present detection agent. In light of various experiments including the experiments described below, on the assumption that impurities such as acid components in the carrier are sufficiently removed by sufficient washing with pure water, silica or Permanganate is supported as uniformly as possible on the surface of the alumina carrier, or on the premise that physical adsorption of THT to silica or alumina as a carrier is suppressed by water-containing moisture. It is also assumed.

As a gas sampling device for sucking the test gas, any of a vacuum type, a feed type, or a bellows type gas sampling device can be used. FIG. 4 shows an example of a vacuum gas extractor among them. This is a method in which the inside of a cylinder of a gas sampling device connected to a detection tube is depressurized by a piston, and a sample gas is sucked through the detection tube.
Is connected to the detection tube. In operation, cylinder 1
When the shaft 20 connected to the piston 19 is moved in the direction of the arrow (→) in the figure with respect to the cylinder 8 to reduce the pressure in the cylinder 18, a predetermined amount of sample gas is introduced into the detection tube. In this case, by setting a gas volume corresponding to the movement width of the piston 19 in advance, a predetermined constant amount of the sample gas can be introduced into the detection tube. In FIG.
Is a check valve, 22 is packing, and 23 is a stopper.

[0022]

EXAMPLES Hereinafter, the present invention will be described in more detail based on experimental examples (test examples), but it is needless to say that the present invention is not limited by these experimental examples. << Preparation of detection agent >> Silica gel (manufactured by Fuji Devison, ID
Mold, 40-60 mesh, average pore size = 140 Å, specific surface area = 300 m ² / g, pore volume = 1.
1 ml / g) was prepared and washed with 5 liters of ion-exchanged water for 5 hours. This washed silica gel 10
0 g was placed in a vacuum flask. This has a concentration of 0.233g
After thoroughly adding and mixing 120 ml of an aqueous solution of potassium permanganate at a temperature of 353 K for 3 hours, the mixture was vacuum-dried for 3 hours. Thereafter, pure water is impregnated and impregnated with water. The water content [= weight of water / weight of silica gel × 100 (%), and the term “water content” is used in the present specification with the same definition] Is prepared, for example, with a water content of 10
%, 30%, 50%, 80% and 100% pure water was added.

<< Preparation of Interfering Substance Remover >> Ion-exchanged water 1
Dissolve 0.6 g of lead acetate in 00 ml.
ml and glycerin 40 ml were added. This solution was placed in a vacuum flask containing 100 g of silica gel (same as above) and mixed well, and then pure water was added so that the water content became 30%. << Preparation of protective agent >> Activated alumina (Fuji Devison, 4
(0-60 mesh, specific surface area = 150 m ² / g, pore volume = 0.54 ml / g) was prepared, and 100 g of this was placed in a vacuum flask. 70 ml of an aqueous solution of potassium permanganate having a concentration of 14.3 g / l was added thereto, mixed well, and dried in a water bath at a temperature of 353 K for 3 hours under vacuum. Then, pure water was added to the dried product so that the water content became 35%.

<< Preparation of Detecting Tube >> The detecting tube in this test example was prepared by dividing into a detecting agent tube and a pretreatment tube. The outline of the constitution of the detecting agent tube is as shown in FIG. 1, but this tube is a glass tube having an inner diameter of 2.6 mm, and other dimensions (except for the fusing portion described below) are the dimensions illustrated in FIG. And In this glass tube, one glass bead 2 having a diameter of about 2 mm, an isolating agent 3 (0.25 g of fused alumina washed with ion-exchanged water), and a detecting agent 0.15 prepared as described above.
g, an isolating agent 4 (0.10 g of fused alumina washed with ion-exchanged water), a protective agent 0.04 g, and a polyethylene resin packing (about 4 mm) 7 are placed and placed, and both ends of the glass tube are blown to detect the agent. A tube was made.

Next, the configuration of the pretreatment tube was as shown in FIG. This tube is a 3.6mm inner diameter glass tube,
The other dimensions were the dimensions illustrated in FIG. The glass tube was filled with the remover prepared as described above so as to be sandwiched between polyethylene packings (3 mm) 12 and 13 and filled as indicated by reference numeral 11 in FIG. The pretreatment tube and the detection agent tube thus manufactured were connected via a rubber tube 16 as shown in FIG. 3 to obtain a detection tube for this example.

<< Test Using Detector Tube (Pretreatment Tube + Detector Agent Tube) >> It is necessary to feed a predetermined amount of sample gas (= test gas) into the above detector tubes (pretreatment tube + detector agent tube). FIG. 5 shows an apparatus including a gas extractor for this purpose.
This apparatus comprises a glass container (approximately 500 ml) 25 provided with a sample gas sampling port 26. First, a sample gas is taken into the container 25 from a gas pipe 24. Next, the tip of the opening of the detection tube (pretreatment tube + detection agent tube) 27 is connected to the sample gas sampling port 2.
6, the sample gas in the container 25 is sucked by the vacuum gas sampling device 28 connected to the end of the detection tube (pretreatment tube + detection agent tube) 27 side, so that the sample gas passes through the pretreatment tube. Guide to the detection agent tube. 29 is an operating rod for that purpose.
In this case, a predetermined amount of the sample gas is made to reach the inside of the detecting agent tube. In this test, a vacuum gas sampler 28 having a suction volume of 100 ml was used. These were housed in a thermostat 30 for maintaining a constant temperature as shown.

As the sample gas (test gas), purified air,
Purified nitrogen (Test 5) and a gas obtained by adding a predetermined amount of THT to the five kinds of gases A to E shown in Table 1 (including the case where THT is not added), and a city gas (Test Various tests were performed using 7). In addition, the numerical values shown in Table 1 are volpp for H ₂ S and C ₂ H ₅ SH.
m and the other components are vol%.

[Table 1]

<Test 1> In this test 1, each of the detecting agents prepared by changing the water content of the detecting agent obtained by loading potassium permanganate on a silica carrier in the range of 0% to 110% was used. The change in the length of the color-change layer due to the rate of change was examined. [The length of the color-change layer refers to the result of each test among the layers of the detection agent in the detection agent tube (the layer indicated by reference numeral 5 in FIG. 1). Is the length of the portion that has changed from pink to white, that is, the length of the layer 5 that has turned white from the left end toward the right.] FIG. 6 shows the result. As shown in FIG.
When the moisture content of the detecting agent is 0%, the detecting agent does not discolor at all,
As the water content increases, the length of the discolored layer gradually increases, and becomes 25 mm at a water content of 50% and 33 mm at a water content of 80%. Above that, there is some increase, but it is almost constant. You can see that. Further, when the case where the water content was 100% or more was observed, it was observed that the discolored layer was unclear, and in this case, "bleeding" was observed in the colored layer, which caused inconvenience such as an increase in reading error. Do you get it.

In Test 1, the test temperature was 293K,
As a test gas in the case of FIG.
Although the sample containing 95 vol ppm was used, the same tendency was shown when the sample gas containing 195 vol ppm of THT in purified methane gas (sample gas shown as A in Table 1) was used. in this way,
The amount of impregnated water (water content) in the detection agent of the present invention can be in the range of about 25% to less than about 100%, preferably about 70 to 90%, and more preferably 75 to 85%. , Particularly preferably in the range of 78 to 82%.

<Test 2> In this test 2, the water content of a detecting agent comprising potassium permanganate supported on a silica carrier was 8%.
The relationship between the reaction time and the length of the discolored layer was determined, depending on the THT content in the test gas, with 0%. Test temperature 293K
And THT in purified air was 3
0 volppm, 60 volppm, 100 volpp
Those containing m and 160 volppm were used.
FIG. 7 shows the result. As shown in FIG. 7, in all the densities, the length of the discolored layer reached a certain level in about 60 seconds (1 minute), and there was almost no change in the length thereafter. It shows that it is possible to perform various measurements.

Further, the length of the discoloration layer is such that the THT content is 30%.
9.5 mm, 60 vol in vol ppm (indicated by a circle in FIG. 7)
16 mm in ppm (marked in Fig. 7), 100 volppm
(□ mark in FIG. 7), 22 mm, 160 vol ppm (FIG. 7)
It is 30 mm in the middle ● mark, and shows a constant discoloration layer length depending on the THT content in the test gas, and shows a highly accurate sharp response corresponding to the THT content. FIG. 7 shows THT in purified air as a test gas.
However, the same tendency was observed when a sample gas containing THT in purified methane gas (sample gas shown as A in Table 1) was used as a test gas.

<Test 3> In this test 3, the water content of the detecting agent comprising potassium permanganate supported on a silica carrier was 8%.
It was set to 0%, and the influence of the measurement temperature on the length of the discolored layer was examined. FIG. 8 is a diagram in which the results are plotted. Using five kinds of test gases having different THT concentrations in the test gas, the test temperature was set to 27 for each THT concentration.
3K (○ in FIG. 8), 283K (△ in FIG. 8), 293
K (□ in FIG. 8), 303K (● in FIG. 8) and 313
K (black mark in FIG. 8), the length of the discolored layer was measured 90 seconds after the end of the suction.

As shown in FIG. 8, in the range of 273 to 313K, the length of the color changing layer changes at most about twice due to the difference in temperature. For this reason, it is necessary to correct the length of the discoloration layer according to the measurement temperature. Table 2 shows an example of the correction, and the temperature correction when the length of the discoloration layer at the measurement temperature of 298K is 1.0. The coefficient is shown.

[Table 2]

<Test 4> In this test 4, the effect of the humidity of the test gas on the length of the discoloration layer was examined.
Four test gases with different THT concentrations (THT concentration: 30
volppm, 60volppm, 100volppm
And 160 vol ppm), the humidity is 50
% And 90%, and those not humidified were measured and the results were compared. As a result, no change was observed in the length of the discolored layer due to humidification. This test 4 shows that when the detection agent according to the present invention is used, the influence of the humidity of the test gas can be ignored.

<Test 5> Ethylene, propylene, hydrogen sulfide, ethyl mercaptan, and the like can be used as interfering gases contained in fuel gas such as city gas and natural gas. Therefore, in Test 5, the effects of these gases on the coloration of the detector tube were examined. FIG. 9 is a diagram showing the results obtained by using a detection tube (pretreatment tube + detection agent tube) based on the results after the preliminary experiment for each of these gases. In FIG. 9, each base gas: N ₂ (indicated by a circle in FIG. 9), N ₂
+ C ₂ H ₄ 5000 vol ppm (△ in FIG. 9), N ₂ +
C ₃ H ₆ 2000 volppm (indicated by □ in FIG. 9), N ₂ + H
₂ S300 volppm (indicated by ● in FIG. 9) and N ₂ + C ₂ H
_The horizontal axis represents the concentration of THT contained in ₅ SH 3.0 volppm (marked with black in FIG. 9), and the vertical axis represents the length of the discoloration layer. As is clear from FIG. 9, up to 5000 vol ppm for ethylene, up to 2000 vol ppm for propylene, up to 300 vol ppm for hydrogen sulfide, and up to 3.0 vol ppm for ethyl mercaptan, by using pretreatment tubes (interfering substance removing agent tubes). This shows that the influence can be eliminated and THT can be measured accurately.

<Test 6> In this test 6, the concentration of THT contained in a composition gas similar to natural gas was determined using FPD-GC
(Gas chromatograph equipped with a flame photometric detector) and the detector tube of the present invention. Five kinds of sample gases A to E shown in Table 1 were used as the composition gas for each test. The result is as shown in FIG. The value measured by the THT detector tube was obtained from the relationship between the THT density and the length of the discoloration layer (see FIG. 9) and the temperature correction (see Table 2). As is clear from FIG. 10, in any case of the sample gas,
The value measured by the THT detector tube was in good agreement with the value measured by FPD-GC, and the difference was found to be within ± 5%. In this regard, according to JIS K 0804, which prescribes the detector tubes that measure various gases, the accuracy of indicating the detector tubes is as follows. It is specified that it should be within ± 25% of the measured value and within ± 15% of the average value of the measured values, but the THT detector tube of the present invention satisfies this rule more than enough.

<Test 7> In this test 7, the THT concentration in the city gas actually supplied to the consumer was determined using FPD-GC
And a detection tube of the present invention (pretreatment tube + detection agent tube). Each measurement was repeated five times. As a result, the value measured by any of the methods was 14 volppm. THT detecting agent according to the present invention and THT using the same
It is clear that the detector tube can be applied very effectively to real gas.

<Test 8> In this test 8, the detection tube (pretreatment tube + detection agent tube) using the THT detection agent of the present invention was stored in a 288K constant temperature room protected from direct sunlight. Even after the lapse of time, the same measurement value as that immediately after the production was obtained. On the other hand, under direct sunlight, the entire detection agent layer turned white in one hour. Therefore, it was found that the performance of the THT detector tube of the present invention can be maintained for a long period of time by storing it at room temperature or lower while avoiding direct sunlight.

[0039]

As described above, according to the detection agent of the present invention, the presence or absence or amount of THT added as an odorant to fuel gas such as city gas can be measured quickly and with high accuracy. . Further, the T filled with the detecting agent of the present invention
HT detector tubes are much better than conventional detector tubes, such as being simple, quick and accurate, and having very few reading errors.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a detecting agent tube filled with a THT detecting agent according to the present invention.

FIG. 2 is a diagram schematically showing a removing agent tube (pretreatment tube) for removing an interfering gas component (H ₂ S or the like) in a sample gas in advance.

FIG. 3 is a diagram schematically illustrating a connection state between a detection agent tube and a pretreatment tube.

FIG. 4 is a diagram showing an example of a vacuum gas sampling device.

FIG. 5 is an apparatus including a sample gas (= test gas) sampler used in the embodiment.

FIG. 6 is a graph showing a change in the length of a discolored layer depending on the water content in the detecting agent of the present invention.

FIG. 7 is a graph showing the relationship between the reaction time and the length of the discolored layer depending on the THT content in the test gas by the detection agent of the present invention.

FIG. 8 is a graph showing the influence of the measurement temperature on the length of the color-change layer in the detection agent of the present invention.

FIG. 9 is a graph showing the results of a study on the effect of the detection agent of the present invention on the coloration of a detection tube of an interfering gas contained in fuel gas such as city gas and natural gas.

FIG. 10 is a view showing the results of measuring the THT concentration contained in a composition gas similar to natural gas using an FPD-GC (gas chromatograph with a flame photometric detector) and a detection tube of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Detecting agent tube 2 Glass beads 3, 4 Isolating agent 5 Detecting agent 6 Protective agent 7 Packing 8, 9 Both ends of detecting agent tube 1 10 Pretreatment tube 11 Remover 12, 13 Packing 14, 15 Both ends of preprocessing tube 10 Part 16 Connection pipe (connection pipe between left end of detection agent pipe 1 and right end of pretreatment pipe 10) 17 Detection pipe mounting port 18 Cylinder 19 Piston 20 Shaft 21 Check valve 22 Packing 23 Stopper 24 Gas pipe 25 Glass Vessel 26 Sample gas sampling port 27 Detecting agent tube or detecting tube (pretreatment tube + detecting agent tube) 28 Vacuum type gas sampling device 29 Operating rod 30 Thermostat

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 31/22

Claims (8)

(57) [Claims] 1. A THT detecting agent in a fuel gas comprising permanganate supported on a carrier, the detecting agent comprising an aqueous solution of permanganate on the carrier sufficiently washed with pure water. , And then sufficiently dried, and then an appropriate amount of pure water is added to cause water to be contained.
Detecting agent. 2. The THT detector according to claim 1, wherein the carrier is silica or alumina, and the permanganate is potassium permanganate. 3. The THT detecting agent in a fuel gas according to claim 1, wherein the water content of the pure water is in the range of 75 to 85%. 4. A method for preparing a THT detecting agent in a fuel gas comprising a carrier made of silica or alumina and a permanganate supported thereon, wherein the carrier is sufficiently washed with pure water. A method for preparing a THT detecting agent in a fuel gas, comprising adding an aqueous solution of permanganate to a carrier, thoroughly drying the solution, and then adding an appropriate amount of pure water to make the carrier water-containing. 5. The method for preparing a THT detecting agent in a fuel gas according to claim 4, wherein said sufficient drying is performed by vacuum drying. 6. A THT detecting tube in a fuel gas comprising a pretreatment tube and a THT detecting agent tube, wherein the THT detecting agent tube contains permanganate on a carrier made of silica or alumina. An aqueous solution of permanganate is added to the THT detecting agent in the fuel gas carried thereon, wherein the detecting agent is sufficiently washed with pure water, and then dried sufficiently. A THT detecting agent tube which is a THT detecting agent tube which is filled with a THT detecting agent which is made hydrated by adding water. 7. The detection tube for THT in fuel gas according to claim 6, wherein the water content of said pure water is in the range of 75 to 85%. 8. The detector tube for THT in fuel gas according to claim 6, wherein said fuel gas is city gas.