JPH03214054A - Method and apparatus for identifying species of combustible gas - Google Patents

Abstract

PURPOSE:To identify from which gas species the component of combustible gas has been derived definitely without error by computing the rate of the concentration of the individual combustible gas component with the concentration value of CH4 as a reference among the measured values of the concentrations of sample gas. CONSTITUTION:Gas whose source is not known and which is leaking in the ground or on the ground surface through soil is made to be a sample gas. The concentrations of components of the combustible gas contained in the sample gas to begin with CH4, the component of inorganic gas such as CO2 and the individual component are measured. Among the measured values of the concentrations of the sample gas, the rate of the concentrations of the individual combustible gas components with the concentration value of CH4 as a reference is computed. Then, which gas species of city gas, fermentation gas or LPG is the source of the combustible gas component contained in the sample gas is identified based on the magnitudes of the concentration values of CH4, the concentration values of the combustible components other than CH4 and the concentration value of CO2 among the measured values of the concentrations and the magnitudes of the operated value of the rate of the concentrations of the individual combustible components contained in the computed sample gas.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to the maintenance and management of gas transmission pipes in urban waste industries and LPG industries whose main raw materials are natural gas, coal gas, and oil gas. This article relates to a method and device for identifying whether combustible gas components contained in gas leaking underground or to the surface of the earth are derived from city gas, fermented gas, or LPG. be.

[Prior Art] Conventional methods and devices for identifying the gas type of combustible gas include detecting a specific component group and identifying it based on that, or using a gas chromatograph, which is a component separation analyzer for gas components. There are known methods in which the person performing the measurement is identified based on the analog output of the chromatogram peak pattern.

[Problems with Prior Art] FIG. 1 illustrates a conventional gas type identification method in the form of a graph. This is an example of an identification type combustible gas detector that uses a catalytic combustion method as the operating principle of the detector. A two-element force formula is used, with detection element B sensitive to all combustible gas components except CH4, and the calculated values of the output values of detection elements A and B, specifically, the output value of element A and the element A method is adopted in which the type of gas is identified based on the level of the ratio to the output value of B. In other words, this is nothing but a method for identifying gas types based on the concentration ratio of CH4 in the total combustible gas components, but if alcohols, esters, etc. are mixed into the combustible gas components, Gases may not be identified accurately. More specifically, if CH4 derived from fermentation gas and alcohol are mixed together, it may be mistakenly recognized as city gas.

For example, the measurer compares the chromatogram peak pattern of a sample gas obtained using gas chromatography with the pre-measured chromatogram peak pattern of city gas or LPG to determine the degree of coincidence of the peak patterns. Is there a way to visually determine the gas type and identify the type of gas?
If either fermentation gas or LPG is present alone, this is a valid method, but if fermentation gas and LPG are mixed, it may be mistaken for city gas, and the measurement person's experience may be a valid method. This method has disadvantages, such as the fact that the identification results may vary from person to person due to differences in the number of people.

Furthermore, all conventional methods and devices for identifying combustible gas types do not take into account atmospheric composition or gas composition in soil, and therefore have the disadvantage that accurate identification may not be possible. ing. Figure 2 shows the results of a soil atmospheric gas survey sampled at over 200 locations in the Tokyo area.

The soil atmospheric gas may contain a large amount of CH, which is a combustible gas component, and CO2, which is an inorganic gas component, produced through the decomposition and fermentation process of organic matter contained in the soil.
For 4, the maximum value is about 50 ppm, and for CO□, the maximum value is 1O%.
A value of about 100% has been detected. In addition, there is C in the general atmosphere.
It contains 1.6 ppm of H4, and if we ignore the hack grand value of these flammable gas components contained in the soil or air, there is a possibility that we will misidentify the gas species from which the combustible gas components originated. . Table 1 shows composition examples of city gas, fermented gas, LPG and dry air.
The concentration of combustible gas components in the sample gas collected at the point where a small amount of CH4 leaked in the soil was several tens of ppm, c
= Ha, C, H, etc. may be several ppm each. In this case, if we do not take into account the Huckland value of CH, it is difficult to understand the origin of the combustible gas components contained in this sample gas. There are some problems, such as the fact that it is sometimes mistaken for city gas.

Margin Table 1 Typical composition examples of gas species (%) and combustible gas components contained in the leaking gas, city gas, fermentation gas, LP
This paper proposes a method and an apparatus for identifying whether the gas originates from any of the G gas species.

[Means for Solving the Problems] As a means for achieving the above object, the present invention uses a gas of unknown origin that leaks underground or to the surface of the earth via soil etc. as a sample gas, and calculates the amount of gas contained in this sample gas. The concentration of each individual component, including combustible gas components such as CH, and inorganic gas components such as CO□, is measured, and when the concentration value of the sample gas is based on the CH4 concentration value. The moisture ratio of each combustible gas component is calculated, and the magnitude of the concentration value of CH, 9 degree value, concentration value of combustible gas components other than CH, and CO2 concentration value among the concentration measurement values, and the calculated sample From the magnitude of the calculated concentration ratio of each combustible gas component contained in the gas, it is possible to determine whether the combustible gas component contained in the sample gas is derived from city gas, fermentation gas, or LPG. Suggest a method to identify whether it is present or not.

In addition, regarding a device for identifying the type of combustible gas, in order to achieve the above object, we propose a combination of each component described below.

A sample introduction pipe for collecting gas of unknown origin leaking underground or to the surface via soil etc. as a sample gas, a sample collection pump installed in the middle of the sample introduction pipe, and a sample collection pump installed in the middle of the sample introduction pipe CH4, C2Ha in the sample gas and installed before or after the sample collection pump.
, C3H8, C3H8, C4H10g, and CO2; a converter that converts the electric signal output from the separation detector into a concentration value of each of the components; a determination circuit that determines from the concentration value of the component whether a combustible gas component contained in a sample gas is derived from any one of city gas, fermented gas, or LPG; and a determination based on the determination circuit. An indicator that displays the results.

[Example] Figure 3 shows an example of an apparatus for identifying the type of combustible gas, and the reference numeral 1 indicates a sample of gas of unknown origin leaking underground or to the surface via soil, etc. This is a sampling nozzle equipped with a filter to remove dust and moisture from the sample gas when sampling it as a gas.

Reference numeral 2 denotes a sample introduction tube on the inlet side of the fractionation detector, which is connected to the sampling nozzle and through which the sample gas passes to the downstream fractionation detector.

Reference numeral 3 denotes a sample introduction tube on the output side of the fractionation detector, which is connected to the output side of the fractionation detector and through which the sample gas passes to the downstream sample collection pump.

Reference numeral 4 denotes a suction type sample collection pump for introducing sample gas into the separation detector through the sampling nozzle and the sample introduction tube.

5 is CH, , C2He, , C-+ Ha contained in the sample gas that passes through the sampling nozzle and the sample introduction tube and is introduced by the suction type sampling pump.
, C-H+o, and C02.

6 is the electrical signal that is the output of the regr classification detector,
This is a converter that converts each of the components into concentration values.

7, based on the concentration value of each component converted by the converter, determine whether the sample gas is a flammable gas component contained in the sample gas, or which type of gas is derived from city gas, fermentation gas, or LPG. This is a judgment circuit.

8 is a display that displays the determination result based on the determination circuit.

Reference numeral 9 denotes an electrical signal corresponding to each of the components, which is an output of the separation detector.

10 is the concentration value corresponding to each of the components, which is the output of the converter.

Here, the separation detector is configured to detect each of the components, that is, CH
Any detector can be used as long as it can individually detect 4, C2H, C, H8, C, H, and CO2 and convert it into an electrical signal.
For example, a gas sensor sensitive only to CH4 and a gas sensor sensitive to C2H6
A gas sensor sensitive only to C3H, a gas sensor sensitive only to C3H, a gas sensor sensitive only to C4HIO, and a gas sensor sensitive only to C02 may be arranged in the sample gas introduction tube to form a separate detector. used two gas chromatograph-type gas separation detection devices with different lengths of gas separation tubes as separation detectors.

FIG. 4 shows an embodiment of a differential detector, with the symbol 2.2'
is the sample introduction tube on the inlet side of the separation detector.

11.11' is a sample gas line valve that opens only when the sample collection pump 4 is in operation.

12.12' is a sample loop provided downstream of the sample gas line valve.

13.13' is a three-way valve, which connects the sample loop side and the downstream sample introduction pipe on the output side of the fractionation detector when the sample collection pump 4 is in operation.

3.3' is a sample introduction tube on the output side of the separation detector.

14 is a stainless steel inner capacity 751 filled with He gas
, a carrier gas cylinder with a filling pressure of 150 kg/cm2 (gauge pressure).

Reference numeral 15 denotes a shutoff valve for preventing outside air from entering the separation detector when the carrier gas cylinder 14 is replaced.

16 is a small primary pressure reducing valve that reduces the carrier gas pressure to 5 kg/cm2 (gauge pressure).

Reference numeral 17 denotes a small secondary pressure reducing valve that further reduces the pressure of the carrier gas reduced through the primary pressure reducing valve to 1 kg/cm2 (gauge pressure).

18.18' is a carrier gas line made of stainless steel.

19.19' and 20.20' are flow path resistance pipes provided downstream of the carrier gas line and made of stainless steel pipes narrowed down.

21.21' is CH,,C2H contained in the sample gas
6, C:l H,, n-C, Hlo, 1-C4H1o and CO□ are separated from each other. 21 is a gas separation tube that separates CH-, C2Hs and CO2 in the sample gas from each other and other gas components. It has the function of separating. Also, 21′
has the function of separating 03H8, n-c, t HIO and 1-C4HIQ in the sample gas from each other and from other gas components. Here, n-C3H8, C4H10 and iC4HIO are compounds that have an isomerism in the structure, and unless they are particularly distinguished, they are C, H, etc. It is expressed as

22.22' is a reference gas separation tube having the same flow resistance as the gas separation tube 21.21', or only the carrier gas flows through this reference gas separation tube 22.22'.

23.23' is a thermal conductivity type detector, which detects the difference in thermal conductivity between the components separated in the gas separation tube 21.21' and the carrier gas flowing in the reference gas separation tube 22.22'. It has the function of converting into electrical signals.

24.24' is a sample gas injection valve, one end of the valve is connected between the sample gas line valve and the sample loop, and the other end is connected between the flow path resistance pipe (19, 19') and the sample loop. It is connected between the gas separation pipes 21 and 21'.

Here, the inventor's experiments revealed whether commercially available fused silica cavillary columns can be used as the waste separation tubes 21 and 21'.
A fused silica capillary column coated with porous polymer pieces on the inner surface was suitable for the purpose of use. The length of the column is 8 m for the gas separation tube 21 that separates CH4, C2H6, and CO;
, n-C4HIO and 1-C4HIO, the gas separation tube 21' was optimally 2 m long. The analog outputs of the thermal conductivity type detectors 23 and 23' obtained under these conditions are shown in Figures 5 (1) and (2). In addition, the calibration of the converter 6 is performed using CH4, C2H6, C3Han C4H with known concentrations.
By preparing a standard gas containing ro, I C4HIO and CO□ and measuring this standard gas,
Preparation: Is it okay to calculate the conversion factor and detection time of the concentration versus electrical signal of each of the above-mentioned components? Utilizing the characteristic that is also sensitive to 0□ and N2, 0□ and N
By analyzing the atmosphere using the atmosphere in which the concentration of the sum of 2 and 2 is always constant as a standard gas, CH, , C2H,,C:
lH,, n-C4H+o, i C4HIO and C0
2. Since the detection time can be determined and the conversion factor between the concentration of each component and the electrical signal can be determined, there is no need to prepare a special standard gas cylinder, and the measurement work can be extremely simplified.

Incidentally, if it is desired to minimize the size of the separation detector 5, a "small gas chromatograph apparatus" described in Publication No. 58-195149 may be used.

The embodiment has the above configuration, and CH, C2H6, C3H8, C4HIO and C contained in the sample gas.
From the measurement data of O
The judgment parameters and judgment flow used in this process are explained below.

B) Extraction of air-derived sample gas Since the flammable gas component of the sample gas may contain only flammable gas below the huck ground level of the soil atmospheric gas, this is extracted as an air-derived sample gas. The necessary and sufficient parameters for making this determination are the CH4 concentration value, C2H5+t:, Ha +C4H
There are two types of parameters for the concentration value of IO. in particular,
Contains only CH4 below pack ground level and C2
H6+C: l Ha +C4Hl. In other words, if the sample gas does not contain any combustible gas components, it is identified as air.

Extraction of sample gas derived from LPG Since the sample gas may contain only combustible gas components derived from LPG, this is extracted as sample gas derived from LPG. The necessary and sufficient parameters for making this determination are the same as those in the previous section (a). Specifically, a sample gas that contains only CH4 below the hack ground level and contains C2Hr, + C:, H, +C4H+o at a certain concentration level or higher is identified as LPG.

c) Identification of sample gas derived from city gas and fermentation gas As shown in Table 1, both fermentation gas and city gas are gas types with CH as a flammable gas component. In order to distinguish between the two while taking into consideration, two points are important: - Does it contain flammable gas components other than CH? - Does it contain CO3, which is produced in large quantities during the fermentation process? becomes.

Therefore, the flammable gas components contained in the sample gas other than the sample gas identified as air or LPG,
C2H6, C, H,, C3H8, C4H when set to 00
Calculate the concentration ratio of 10 and calculate each as y (C2Hg
), y(C3HA), Y (C4Hl(1), y
(C2H6) +y (C3Ha) +y (C-
Hlo) and CO□ concentration are also used as parameters to identify city gas S and fermentation gas.

Specifically, y (CZ H6) + y (C Ha
) + y (C4HIO) is within a certain level range, and y (C2H6) is a value above a certain level and does not contain CO2, in other words, the gas contained in the sample gas The main component is CH4, and C2
For poems that contain Hs, C3Ha, and C4HIO at a certain level but do not contain CO□, it can be judged that the composition of the combustible gas component in the sample gas is very similar to that of city gas, and this sample gas and city gas are identify

Also, y (C2H6) +y (c:I Ha)
+y When (C, H,,) is a value below a certain level, that is, the combustible gas component contained in the sample gas or CH is the main component, C2H6, C:l Ha, C4H
When it contains almost no IQ, it can be determined that it matches fermentation gas, and this sample gas is identified as fermentation gas.

2) Identification of sample gas containing two or more types of city gas, fermented gas, and LPG According to the previous paragraphs a), 5), and 3), if the sample gas contains a combustible gas component, its origin can be determined. It is possible to identify whether the gas type is city gas, fermented gas, or LPG. In addition, if it does not contain flammable gas components, it is classified as air. However, there may be cases where the combustible gas component contained in the sample gas originates from two or more gas types. This is achieved by Note that the target of this identification is a sample gas other than the sample gas identified as air or LPG.

■ Identification of sample gas mixed with fermentation gas and LPG (
C2H6)+! /CC3Ha)+y(c,Hlo)
It is a large value above a certain level, and 3'(C2
H6) If the level is below a certain level, CH4, C:I Ha
,C4Hl. Judging from the gas composition in Table 1, this sample gas contains only fermentation gas and L.
It is identified as PG or mixed.

■ Identification of sample gas containing city gas and LPG (
C2H6) +y (C3He) +y (C4Hl
t+) is greater than a certain level, Y (C2H6) is greater than a certain level, and does not contain CO2, as a combustible gas component contained in the sample gas. ,CH,,C2H5,C3H8,C
This means that 4HIO is present, and the derived gas species are a mixture of city gas and LPG.

■ Identification of sample gas where city gas and fermentation gas are mixed Y (C2H6”) +Y (C:l Ha
)+y(C4HIQ) is a value within a certain level range, and when y(C2H6) is a value above a certain level and contains CO2, in other words, the components contained in the sample gas are CH , with C2H6 as the main component
, C3Hs, and C4HIo at a certain level or more and also CO□, it is judged that the composition of the combustible gas component in the sample gas closely matches that of city gas, and since CO2 is included, This sample gas is identified as a mixture of city gas and fermentation gas.

■ Identification of sample gas mixed with city gas, fermentation gas, LPG y (C2H6) +y (C:+Ha) +y
(C4Hlo) has a large value above a certain level, and when y (C2Hs) is above a certain level and contains CO2, CH4, C2Hs, C:l Ha
, which means that C4HIo is present, and also CO2
This means that the three types of gases that are derived are city gas, fermented gas, and LPG, or a mixture of them.

Figure 6 shows, as an example, CH4 and C2H6 in the sample gas.
, C3Ha, C4HIO and CO2, and the five parameters namely CH4 concentration, C2H6+
C: + Ha + C4Hro concentration, CO2 concentration, y
(C2H6) +y (C:l Ha) +y (C
4Hlo) and V(C2Hr, ) for gas type identification. If this flow is used, CH4, C2H6, C3Ha in the sample gas
, C4HIQg, and CO2, and determine the concentration ratio using simple calculations to identify whether the sample gas is derived from IT7 combustible gas components, city gas, fermentation gas, or LPG. It becomes possible.

[Effects of the present invention] The effects obtained by the method of identifying the type of combustible gas, which is one aspect of the present invention, are as described below.

a. Flammable gas components or city gas contained in the sample gas,
Anyone can clearly and accurately identify whether the gas originates from fermentation gas or LPG.

b. It is possible to reduce leak investigation work that occurs based on misidentification of gas types.

Next, the effects obtained by the device for identifying the type of combustible gas will be described below.

Since it is extremely easy to assemble as a C0 field-portable automatic analysis/identification device, if this device is used,
It is possible to reduce the burden of leakage investigation on site.

Even an operator without knowledge of d1 analysis or experience in leakage investigation will be able to identify waste types between short poems without error.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional method for identifying waste types in detail. Figure 2 shows the analysis results of soil atmospheric gases collected from over 200 locations in Tokyo. FIG. 3 is an explanatory diagram of a device for identifying the type of combustible gas. Fourth
The figure is an explanatory diagram of a separation detector. Figure 5 (1), (2)
is an explanatory diagram of analog output of a thermal conductivity type detector. 6th
The figure is an explanatory diagram of the determination flow. 1 ... Sampling nozzle 2 ... Separation detector inlet sample introduction tube 3 ... Separation detector outlet sample introduction tube 4 ... Pump 5 ... Separation detector 6 ... Exchanger 7 ... Judgment circuit 8 ... Display 9 ... Denki Gin lO-... Concentration value 11.11'... Sample gas line valve 12.12
'... Sample loop 13.13'... Three-way valve 14... Carrier gas pump 15... Shutoff valve 16°... Primary pressure reducing valve 17... Secondary pressure reducing valve 18.18'... ... Carrier cast line 19.19'
, 20.20' -... Flow path resistance tube 21.21'
... Gas separation tube 22.22'... Reference gas separation tube 23.23'... Thermal conductivity type detector 24.24'.
・・Valve for sample gas injection

Claims (2)

[Claims] (1) Gas of unknown origin that leaks underground or to the surface via soil etc. is used as sample gas, and combustible gas components such as CH_4 and CO_2 contained in this sample gas are used.
Measure the concentration of each inorganic gas component and each component, calculate the concentration ratio of each combustible gas component based on the CH_4 concentration value among the measured concentration values of the sample gas, The magnitude of the CH_4 concentration value, the concentration value of combustible gas components other than CH_4, and the CO_2 concentration value in the measured concentration values, and the calculated value of the concentration ratio of each combustible gas component contained in the sample gas calculated above. Based on the size, the origin of the combustible gas component contained in the sample gas is city gas, fermentation gas, L
How to identify which type of gas is PG. (2) A sample introduction pipe for collecting as a sample gas a gas of unknown origin leaking underground or to the surface via soil, etc., and a sample collection pump installed in the middle of the sample introduction pipe, and the sample introduction. CH_4, C_2 in the sample gas installed in the middle of the pipe and before or after the sample collection pump
H_6, C_3H_8, C_4H_1_0 and CO_
2; a converter that converts the electric signal output from the separation detector into a concentration value of each of the components; a determination circuit that determines whether the combustible gas component contained in the gas is derived from one of city gas, fermented gas, and LPG; and a display that displays a determination result based on the determination circuit. A device for identifying the type of combustible gas consisting of.