JPS595954A - Method and apparatus for quantitatively measuring natural gas components - Google Patents

Abstract

PURPOSE:To attain to shorten an analytical time to a large extent and to enhance the separation capacity of ethane, in quantitative analysis of a natural gas due to a two-column gas chromatograph, by utilizing the passing time difference of two precut columns. CONSTITUTION:A natural gas specimen 1 is continuously introduced into a flowline 10 while a carrier gas 9 is continuously introduced into a flowline 11 and ten-way valves 12, 13 are revolved to divide the specimen 1 into divided specimens 2, 3. One specimen 2 is passed through a precut column 4 for heavy hydrocarbon equal to or higher than ethane through the valve 12 while the other specimen 3 is introduced into an air.methane precut column 6 through the valve 13 and the one specimen 2 is introduced into an air.methane measuring column 5. Because the other specimen 3 contains a large amount of air and methane, the passing time thereof is delayed. The valves 12, 13 are revolved to introduce the residual amount from which air and methane are precut into a heavy hydrocarbon measuring column 7. By utilizing passing time difference of the columns 4, 6, heavy hydrocarbon can be successively detected by a detector 8 succeeding to air and methane.

Description

[Detailed Description of the Invention] Using a carrier gas, two divided materials are passed in parallel through a column for pre-cutting heavy hydrocarbons of ethane or higher, and the other is passing through a column for pre-cutting air fist methane. The above heavy hydrocarbons are pre-cut and introduced into a column for measuring air/methane, and from the other side, air φ methane is pre-cut and introduced into a column for measuring heavy hydrocarbons of ethane or higher. The present invention relates to a method for quantifying natural gas components and an apparatus therefor, which is characterized by detecting air, methane, and hydrocarbons heavier than ethane using a detector using the difference in passage time between columns.

Conventionally, quantitative analysis of natural gas has been carried out using a one-detector, two-column type gas chromatograph, which has drawbacks.

a) Adsorption columns for quantifying air and methane have a strong affinity for heavy hydrocarbons, so the separation time t is long (approximately 60 minutes, see Figure 2), and the chromatogram drawn is not quantitative. Since it appears as a ghost peak (see Figure 2) without a trace, it has become impossible to analyze j± during that period.

b) In the case of distribution type columns for quantifying heavy hydrocarbons of 50% or more, since the proportion of methane in natural gas is large, the combined peak of air and methane causes a tailing T, making it impossible to separate the ethane peak. The accuracy of ethane determination is not very good (see Figure 2).

c) 1st inspection - For materials whose composition changes sequentially, such as spot A material taken out from the pipeline because it is a small vessel and is used by switching columns, the material composition may fluctuate due to differences in material collection time. Not quantitative.

The purpose of the present invention is to significantly shorten the analysis time and improve the separation performance of ethane by using two columns in parallel in the quantitative analysis of natural gas using a two-column gas chromatograph. be.

To explain the embodiment of the present invention shown in the drawings, it has one detector 8, and a column 5 for measuring air/methane and a column 7 for measuring heavy hydrocarbons of ethane or higher are connected in parallel to the detector 8. , two 10-way valves 12 and 13 are provided to connect the flow path 10 for the natural gas material 1 and the flow path 11 for the carrier gas 9. One of the valves 12 and the column 5 for measuring air/methane are connected through a flow path 11 for carrier gas 9, and the other valve 13 and the column 7 for measuring heavy hydrocarbons are connected through a flow path for carrier gas 9. Connected at 11. Both valves 12 and 13 are connected by a flow path 10 of the natural gas sample 1, and the flow path 10 forms a series of flow paths as shown in FIG. Further, the heavy hydrocarbon pre-cut column 4 is connected to the air/methane measurement column 5 via the flow path 11 via one of the valves 12, and the air/methane pre-cut column 6 is connected via the other valve 13. is connected to the column 7 for measuring heavy hydrocarbons by a flow path 11. The parts other than the one detector 8, the air/methane measurement column 5, and the heavy hydrocarbon measurement column 7, that is, the natural gas sample 1 and the operating device part of the carrier gas 9 are connected to an automatic puncture flush device. Say 16.

In addition, 14 and 15 in the figure are metering tubes, 17 in FIG. 1 is a pressure regulating valve of the carrier gas introduction part, 18 is a pressure gauge, and 19
is a flow meter, 20.21 is a diaphragm type pneumatic slider of the valve 12.13, 22 is an air pipe for its operation,
23 is an inlet valve of the natural gas sample 1, 24 is a flow meter, 25 is an atmospheric pressure balance valve, 26 is an outlet valve of the above sample 1, 27 is a manometer, and 28 is a flow path resistance.

In the present invention, as shown in FIG. 4, a natural gas sample 1 is continuously introduced into the flow path 10, and a carrier gas 9 is continuously introduced into the flow path 11. and the above two lO valves 12.1
3 is simultaneously rotated in the direction of the arrows from the position shown in Figure 4 to the position shown in Figure 5 (sliding from the solid line position to the imaginary line position in Figure 1), the introduced continuous natural gas material 1 becomes two pieces. The two materials 2.3 are divided into divided materials 2.3, and both materials 2.3 are each supplied with a carrier gas 9. One 2 is passed through a valve 12 to a column 4 for pre-cutting heavy hydrocarbons such as ethane, and the other 3 is connected to a column 4 through a valve 13. The air and methane pre-cut columns 6 can be passed through the air and methane pre-cut columns 6 in parallel. The heavy hydrocarbons can be pre-cut (separated) from one of them 2 and air/methane can be subsequently introduced into the air/methane measurement column 5 (see FIG. 5). Meanwhile, the other 3 passes through the air/methane pre-cut column 6, and since the amount of methane in the air is large, the passing time is delayed. In this state, the valves 12 and 13 are further rotated to the positions shown in FIG. 6, and the remaining amount after pre-cutting air and methane can be introduced into the column 7 for measuring heavy hydrocarbons. Above valve 1
2. The above rotation in 13 is operated by a set timer,
The air number methane that has passed through the air/methane measurement column 5 is detected by the detector 8 using the difference in transit time between the two pre-cut columns 4 and 6, and then the polarity switch of the gas chromatograph is switched from positive to negative. Subsequently, the heavy hydrocarbons including ethane which have passed through the column 7 for measuring heavy hydrocarbons can be detected by the detector 8. The detection state is as shown in FIG.

Since the present invention uses the above-described method and apparatus, it is possible to separate the heavy hydrocarbons in advance when quantifying air and methane, and to remove non-quantitative ghost peaks from the drawn chromatogram. In addition, when quantifying heavy hydrocarbons such as ethane, most of the air and methane in natural gas can be separated in advance, and the ethane peak can be completely separated without causing tailing T in the air and methane content peaks. (See Figure 2) Not only can the accuracy of ethane determination be improved, but also the determination of air Φmethane and the above-mentioned heavy hydrocarbons can be carried out quickly. Since the obtained natural gas data are the same, reliable quantitative accuracy can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the natural gas component determination device of the present invention, Fig. 2
The figure shows natural gas component determination using conventional methods and equipment.
Figure 3 is a diagram of natural gas component quantification using the method and device of the present invention, Figure 4 is an explanatory diagram of the state before quantification by the same equipment, Figure 5 is an explanatory diagram of parallel pre-cutting of divided materials, and Figure 6 is a diagram of detection. An explanatory diagram of the conventional method and apparatus for quantitative determination using a device,
FIG. 7 is an explanatory diagram of a conventional device. 1. Continuous natural gas materials, 2, 3. Divided materials, 4.
Column for pre-cutting heavy hydrocarbons greater than ethane, 5.
・Column for measuring air/methane, 6. Column for pre-cutting air [phase] methane, 7. Column for measuring heavy hydrocarbons of ethane or higher, 8. Detector, 9. Carrier gas, i
o, 11...Flow path, 12.13...Valve. Patent Applicant: Kitakyushu LNK Co., Ltd. Yo Takuro Δx'+ to Mulberry to Ajiwara Δ- to Eight Dos

Claims (1)

[Claims] ■) Two divided materials 2 and 3 are separated from the continuous natural gas material 1 introduced into the flow path by a gear gas 9, and one of the materials 2 is divided into a column 4 for pre-cutting heavy hydrocarbons of ethane or more. ,
The other 3 passes air and methane pre-cut columns 6 in parallel, the heavy hydrocarbons are pre-cut from one 2 and introduced into the air-methane measuring column 5, and the other 3 pre-cuts air and methane. is introduced into column 7 for measuring heavy hydrocarbons heavier than ethane, and air/methane and heavier hydrocarbons heavier than ethane are detected by detector 8 using the difference in passage time between the two pre-cut columns 4.6. A natural gas component determination method characterized by: 2) A column 5 for measuring air/methane and a column 7 for measuring heavy hydrocarbons greater than ethane are connected in parallel to one detector 8, and a flow path 10 for natural gas sample 1 and a flow path 11 for carrier gas 9 are connected in parallel. Two valves 12 and 13 are provided to connect the air/methane measuring column 5 to the carrier gas 9, and the other valve 13 and the heavy hydrocarbon The measurement column 7 is connected to the flow path 11 of the carrier gas 9, and both valves 12 and 13 are connected to the flow path 1 of the natural gas material 1.
0, the heavy hydrocarbon pre-cut column 4 is connected to the air/methane measurement column 5 via one valve 12, and the air/methane brecut column 6 is connected via the other valve 13. A natural gas component quantitative device connected to the column 7 for measuring heavy hydrocarbons. 3) The natural gas component metering device according to claim 2, wherein each of the two valves 12 and 13 is a 10-way valve.