JPS60120248A - Gas analyzing apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect a component unnecessary to separate as one peak without mixing the same with a component to be analyzed, by a back- flash valve and a back-flash column having a specific length. CONSTITUTION:A back-flash valve is a back-flashing flowline change-over valve and includes a back-flash cock and a flowline change-over cock to a back-flash column. In this case, the length of the black-flash column is set to about 8-15m because, if said length is below 8m, the separation of a component having a b.p. equal to or less than that of, for example, propane can not be sufficiently performed and one having a length exceeding 15m sufficiently performs the separation of a low b.p. component but is made long in a time required in elution and is not pref. from an aspect for attaining to shorten a time. Further, in the analysis of natural gas, the use of the back-flash column having a length of 9-12m is pref. because good separation of a component and the shortening of a time can be performed.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention is directed to gas analysis using a gas chromatography method having a backflush column system that can shorten the analysis time and perform component separation well. The present invention relates to devices, particularly natural gas analyzers.

(B) Prior art A so-called total analysis, in which a gaseous sample containing multiple components is separated into individual components by gas chromatography and analyzed for all of the components, is not always performed, and sometimes quantitative analysis of specific components is performed. Alternatively, quantitative analysis of each component having a lower boiling point than a specific component is performed using a gas chromatograph. Therefore, in the case of gas chromatography analysis of these specific components, it is not necessary to separate each component other than the specific target component, so for example, components that do not require separation are A so-called backflush column system is used to separate the peaks and detect them as a single peak.

In particular, in the analysis of natural gas, for example, only low boiling point components of penta/lower are separated and detected as individual peaks, and high boiling point components of hexa/or higher are back-7 lasiered during the separation. , are combined into one peak and detected.

However, when natural gas is analyzed by gas chromatography, in order to separate methane and air, the elution time of pentane having 5 carbon atoms, that is, Cs, and hexa/C-, becomes longer. Therefore, air, methane, ethane,
Propane, isobutane, n-butane, impentane, n
- When analyzing natural gas for high-boiling components of pentane and hexane or higher, they usually elute in order of boiling point, so after n-pentane has eluted, a bank flush is performed to remove the total amount of high-boiling components of hexane or higher. I'm looking forward to it. However, according to such a method, even if it takes about 30 minutes to elute n-pentane, it takes about 60 minutes, which is twice that amount, to elute the total amount of high-boiling components higher than hexane, which takes a long time. I ran into problems trying to shorten that time.

Therefore, in order to solve these problems, conventionally, the length of the backflush column has been shortened to speed up the elution, usually from around 3 m to around 6 m at most. . However, when the length of the column is shortened in this way, the separation of components below propane, for example, is insufficient, which is a problem.

19 Purpose The present inventor has made the length of the backflush column longer than the conventional one, from 8 to 15 m.

Preferably, even if it is 9 to 12 m, the timing of performing pack 7 latency is earlier than in the case of conventional equipment, so that components that do not require separation can be grouped together without being confused with the components to be analyzed. It has been found that not only can it be detected as a single peak, but the target analyte component can be sufficiently separated.

The present invention is based on such knowledge and aims to solve the problems of conventional devices all at once.

That is, the present invention provides a gas analyzer, particularly a natural gas analyzer, using a bank flush system that can perform better separation of target components and shorten analysis time compared to conventional devices. be.

) Configuration The present invention comprises backflush pulp and about 8 to 15
A gas analyzer using gas chromatography is characterized in that it has a bank flash column having a length of m.

In the gas analyzer of the present invention, a commonly used column can be used as the backflush column. The dimensions that determine column length are not exact;
Usually, it is determined within a range based on the dimensions that are sold and sold.

The reason why the length of the backflow column used in the present invention is 8 to 15 m is because the length of the backflow column is less than 8 rIL, for example,
It is not possible to sufficiently separate low boiling point components below propane, and if the length exceeds 15 m, the low boiling point components can be separated sufficiently, but the time required for elution is long and the time is shortened. This is because it is not preferable in terms of shortening the length.

By the way, in general, when separating gaseous components, it is necessary to increase the length of the backflush column as the number of components to be separated and the upper and lower temperature ranges of the boiling points of the components to be separated increase. In the present invention, for example, in the analysis of natural gas, when attempting to separate low boiling point components below propane, it is recommended to use a backflush column with a length of 9 to 12 m to achieve good component separation and separation time. This is preferable because it allows the shortening of .

In addition, packfludge pulp refers to flow path switching pulp for backflushing in gas chromatographs.
Includes a backflush cock and other flow path switching cocks to the backflush column.

A gas analysis method using the gas analyzer of the present invention will be explained using, for example, a method for analyzing low boiling point components of n-pentane or lower in natural gas.

In the gas analyzer of the present invention, low-point components below n-pentane elute in the order of their boiling points, but in the gas analyzer of the present invention, for example, when backflushing is performed at the point when propane has eluted, the bank flush column Because of the length of 8 to 15 m, it has already been separated into isobutane, n-butane, isopentane, and n-pentane, which are then eluted and detected. The high boiling point components of hexane or higher are detected together as a single peak, and do not mix with the target component to influence the analysis results.

(E) Embodiment FIG. 1 is an explanatory diagram of an embodiment of the gas analyzer of the present invention.

The Lube 1 is a so-called hexagonal pulp that connects a metering tube 2 and has an inlet 3 and an outlet 4 for a sample gas, and an inlet 5 and an outlet 6 for a carrier gas,
Its carrier gas outlet 6 is connected to the inlet 8 of the tube 7. Back flannel sea column 12
is connected to the connection port 9.11 of the backflush valve 7, and the outlet 10 of the backflush valve 7 is connected to the detector 14, e.g., a thermal conductivity detector (
TCD). (Tsuku Flash Column 12)
A 9 m long device using Silico 7DC2001500 as the stationary phase liquid is used.

In the gas analyzer of the present invention shown in Fig. 1, the sample introduction system (
Not shown. ) The introduced sample gas, for example natural gas, is introduced from the gas port 3, flows along the solid line flow path in the sampling valve 1, passes through the metering tube 2, and flows out from the sample gas outlet 4. On the other hand, carrier gas, for example helium gas - carrier gas population 5
The gas enters the sampling valve 1 through the solid line flow path in the valve 1, and flows from the carrier gas outlet 6 to the backflush column 12.

Therefore, when the sampling pulp 1 is switched, a carrier gas such as helium gas enters the sampling valve 1 from the carrier gas population 5, flows through the dotted line flow path in the valve 1, and the sample gas in the metering tube 2, For example, natural gas is passed from the carrier gas outlet 6 through the solid line flow path of the backflush valve 7 to the back 7 rack column 1.
Stream to 2. A sample gas, such as natural gas, is separated into components, and the components are eluted in order of boiling point. In the case of natural gas, the components that are separated and eluted are components with low boiling points such as prono(n), and they are dissolved in the order of boiling points, that is, air, methane,
Ethane and propane are eluted in this order and are sequentially detected by the detector 14.

Now, when the elution of propa7 (C3H8) is detected, the flow path of the flush valve 7 is switched to perform backflushing.In this case, the carrier gas is
) (flows in the order of the dotted lines in the lube 7, flows in the reverse direction in the backflush column, and the components in the column are pushed out in the opposite direction and eluted. By this backward extrusion by the carrier gas, High boiling point components higher than hexane (
C, +) elutes first, followed by n-pentane, impenta/, 11-butane, and isofurino, that is, the elution order is reversed.

FIG. 2 shows the gas chromad duram of natural gas with low boiling point components of n-pe/tan or less produced by the apparatus of this embodiment.
High-boiling components higher than C6+ hexane are grouped together and detected as one peak. On the other hand, air
, methane (CH4), ethane (C2He), propane (C5Hs), isobutane (i-C4H1), n-
Butane (n-C4H1O), isopentane (i-C,
H,2) and n-penta7 (n-C3H12) have narrow peak widths and clear peaks, and are well separated. Further, there is no possibility that a component with a low boiling point of n-pentane or lower is mixed into the C6+ component and the analysis becomes impossible.

Moreover, in this case, natural gas analysis is performed within about 40 minutes.

On the other hand, Figure 3 shows a gas chromatogram of natural gas analysis using a conventional device, but due to backflushing when the n-pentane peak is detected,
A CI+ peak (not shown) appears at about 100 minutes.

Therefore, when comparing the gas analyzer of the present invention with the conventional apparatus, it is found that with the conventional apparatus, it takes about 100 minutes to analyze natural gas even when using the backflush method. Therefore, it can be seen that the gas analysis apparatus of the present invention reduces the time required for analysis by more than half compared to the conventional apparatus.

(F) Effect The present invention provides a bank flash column with a length of 8 to 15 m, unlike 3 to 6 m in the case of a conventional gas analyzer.
, preferably as long as 9 to 12 m, making it possible to perform bank flushing earlier than in the case of conventional gas analyzers, and sufficient separation of target components can be achieved in a short analysis time. It is something. Moreover, the total peak of high boiling point components can be obtained in an extremely short time without mixing low boiling point components. Further, the detection sensitivity of the total peak of high boiling point components does not decrease.

By making the bank flush column longer, analysis can be performed using one type of column, which simplifies the device structure.

As described above, the gas analyzer of the present invention has many advantages over conventional devices, and its influence is significant.

[Brief explanation of drawings]

FIG. 1 is a flow path explanatory diagram of an embodiment of the gas analyzer of the present invention. Figure 2 shows a gas chromatogram of natural gas analysis using the gas analyzer of the present invention1), and Figure 3 shows the following:
This is a gas chromatogram of natural gas analysis using a conventional device. In the figure, 1 is the sampling pulp, 2 is the measuring tube, and 3
is the sample gas inlet, 4 is the carrier gas inlet, 7 is the backflush pulp, 12 is the backflush column,
13 is a resistance tube, and 14 is a detector. Procedural Amendment (Method) 59.3.19 Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1. Indication of the case, Patent Application No. 228113, filed in 1982. 2. Name of the invention: Base analysis device 3. Amendment. Relationship with the patent applicant’s case Name of patent applicant (199) Shimadzu Corporation 4, Agent

Claims (1)

[Claims] Gas chromatography gas analyzer having a pack-flush valve and a back-flush column having a length of about 8 to 15 m, costing $11.