JP2619494B2 - Analyzer for gaseous matter containing easily condensable gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an analyzer for gaseous matter, and particularly to the analysis of pyrolysis gas of hydrocarbons, even if an easily condensable gas is contained as an impurity. The present invention relates to an analyzer that does not reduce analysis accuracy due to condensate.

<Prior art and its problems> In recent years, for the purpose of reducing the cost of petrochemical raw materials, utilization of various kinds of hydrocarbons as petrochemical raw materials has been studied. For such a wide variety of hydrocarbons, prior to the start of use on an industrial scale, a thermal cracking test of the raw material is performed in advance, and if the thermal cracking composition is grasped, the added value of the raw material can be properly determined. can do.

For this reason, there is a strong demand for a pyrolysis gas analyzer having a rapid measurement process and high accuracy.

However, in the analysis of a mixed gas having a wide boiling point range from a gas having a very low boiling point, such as a pyrolysis gas of hydrocarbons, to an easily condensable gas that liquefies at normal temperature and pressure, which has a high boiling point, this gas is analyzed during gas analysis. There is a problem that such easily condensable gas is condensed, so that the whole gas cannot be analyzed at once, and the mixed gas is cooled once, separated into gas and liquid, and the amount and composition of each of the two phases are determined. It is well known that a method of determining the entire composition, that is, a method of liquefying and separating a high-boiling component and performing analysis of the remaining gas component and analysis of the high-boiling component, respectively, is used.

In this method, when the raw material supply amount is extremely small compared to the industrial scale, such as in a thermal decomposition test apparatus, the amount of the decomposed gas and the amount of the liquid are very small. Has a disadvantage that it is a major factor that causes an error in the decomposition composition. Further, there are disadvantages that the sampling operation of the decomposition gas is troublesome and requires a long time.

In the thermal cracking reaction of hydrocarbons, water vapor is generally used industrially as a diluent gas for the reaction.However, in a thermal cracking reaction test apparatus before the use is started on an industrial scale, nitrogen gas is used as a diluent gas. The analysis is performed by a gas analyzer including a sampling passage and gas chromatography.

When nitrogen gas is used as the diluent gas, the sampling of the pyrolysis reaction gas can be automated and the nitrogen gas can be used as an internal standard gas for gas chromatography.

In such a gas analyzer, means for preventing liquefaction of the condensable gas in the middle of the sampling passage of the pyrolysis gas includes raising the sample gas temperature to prevent liquefaction of high-boiling components and keeping the sampling passage warm. Or removing a droplet by providing a filter at the outlet of the thermal decomposition reaction furnace.

However, in the case of a pyrolysis gas containing a large amount of easily condensable gas, there is a limit in preventing liquefaction even if such a means is used. In addition, removal of the liquid once liquefied on the way requires purging with an inert gas for a long time in some places, and if it cannot be completely removed, it will affect the next analysis, and accurate analysis will be required. become unable.

In particular, high-boiling components liquefy near the solenoid valve at the inlet of the inlet to the gas chromatography, and when these droplets reach a certain volume, they separate from the tube wall and are pushed into the gas chromatography. The baseline of the measured value is pushed up as the number of measurements increases.

This measurement error occurs more greatly as the boiling point increases, and the measured value becomes unreliable. This droplet cannot be completely removed even by the low-temperature trap. Further, it is not preferable in terms of gas analysis that the temperature of the sampling gas is changed by the low temperature trap.

<Problems to be Solved by the Invention> An object of the present invention is to provide an analyzer for a gaseous substance containing an easily condensable gas, such as an analyzer for a hydrocarbon gas in a thermal cracking test apparatus, in which the condensable gas is analyzed by ordinary means. In addition to suppressing liquefaction, even in the event of liquefaction, the liquid can be easily discharged out of the system, and the structure does not allow the liquid to enter the analyzer, so accurate analysis data of pyrolysis gas An object of the present invention is to provide an analyzer capable of obtaining the following.

<Means for Solving the Problems> That is, the analyzer for a gaseous material containing an easily condensable gas of the present invention is provided with a sampling passage for a gaseous material containing an easily condensable gas, and a downstream side of the sampling passage. A discharge passage for discharging a condensate of the easily condensable gas condensed in the sampling passage from the sampling passage at a lowermost position of the sampling passage. Is provided at an uppermost point position of the sampling passage downstream of a lowermost point position of the sampling passage, and an inlet of the gaseous matter analyzer of the sampling passage is connected via a valve. A purge line is connected to a position downstream of the valve at the inlet of the gaseous substance analyzer and adjacent to the valve, and the sampling passage is directed upstream and the analyzer is downstream. Characterized in that it is structured to flow a cleaning nitrogen gas toward.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments shown in the drawings.

 FIG. 1 is a diagram illustrating an analyzer according to the present invention.

The present invention relates to an analyzer having a gas analyzer 2 for gaseous substances (hereinafter sometimes simply referred to as gas) such as gas chromatography and a gas sampling passage 1 communicating therewith. And means for discharging a liquid which is a condensate in the gas.

This liquid discharging means is a discharging path 5 provided via a valve 4 at the lowest point of the sampling path. The sampling passage 1 and the inlet of the gaseous substance analyzer 2 are connected via a valve 8 at the highest point of the sampling passage downstream of the lowest point of the sampling passage.

With these configurations, the liquid remaining in the sampling passage 1 can be discharged through the discharge passage 5 by opening the valve 4. Further, it is possible to prevent the liquid in the sampling passage 1 from entering the gas analyzer 2.

Further, the present invention has a purge line described below. The purge line 6 includes the sampling passage 1 and
The gas analyzer 2 is interposed via the valve 7. When a cleaning gas, which is N ₂ gas, flows through this purge line, the cleaning gas flows through the sampling passage 1 toward the upstream side, and the cleaning gas flows through the gas analyzer 2 toward the downstream side.

In particular, as shown in FIG. 1, when a purge line is inserted at a position close to the downstream side of the valve 8 which is an electromagnetic reduction at the inlet of the gas introduction pipe of the gas analyzer 2, the easily condensed components in the gas are Since the liquid is easily liquefied near the valve and the liquid is easily stored, the cleaning gas flows to the upstream side of the sampling passage 1 through the valve 8, and the liquid stored near the solenoid valve is easily purged by the cleaning gas. At the same time, the cleaning gas is also supplied to the analysis / measurement unit 3 of the gas analyzer 2, and the analysis / measurement unit is also purged.

Next, the operation of the present invention will be described with reference to an example in which the present invention is used in a hydrocarbon gas analyzer of a pyrolysis test apparatus.

Hydrocarbons are introduced into the heating furnace 10 shown by the dotted line in FIG. 1 together with nitrogen gas for dilution.

This hydrocarbon, for example, before the process of cracking naphtha oil in this plant is started on an industrial scale, a small amount of hydrocarbon oil such as naphtha oil is thermally cracked, and the pyrolysis reaction product is subjected to gas analysis. Thus, a thermal cracking test is performed to determine the added value of the raw material of the plant.

The hydrocarbon is vaporized in the heating furnace, passes through the sampling passage 1, and is analyzed for its composition by a gas analyzer 2 such as gas chromatography.

However, in the conventional example, when an easily condensable gas which is a high boiling point component is contained in the hydrocarbon, it is condensed and liquefied near the valve 8 which is an electromagnetic valve at the gas introduction pipe inlet of the sampling passage 1 and the gas analyzer 2. When this amount reaches a certain amount, the gas is carried into the gas analyzer 2 together with the gas to be analyzed, and the analysis accuracy is reduced.

For this reason, the analyzer of the present invention uses the purge line 6
The valve 4, the valve 7, the valve 8 and the valve 9 are opened, and a cleaning gas such as dry nitrogen is flowed in advance to purge the sampling passage 1 and the analysis / measurement unit 3 at the same time. Also, during the gas analysis, the gas outflow from the heating furnace 10 is appropriately stopped, and the sampling passage 1 and the analysis / measurement unit 3 are purged with a cleaning gas to suppress the liquefaction of the condensable gas. Not to enter.

Further, the valve 4 can be opened from the discharge path 5 located at the lowest point of the sampling path 1 to appropriately discharge the liquid stored in the sampling path 1 to the outside of the system.

The purge amount of nitrogen gas as a cleaning gas is 1 to
The range of 10 l / min is preferable, and the purge with nitrogen gas is preferably continued until just before introducing a sample gas such as a hydrocarbon into gas chromatography.

<Example> Hereinafter, the results of gas analysis using the analyzer of the present invention shown in FIG. 1 will be shown, and the present invention will be specifically described.

(Example) Benzene, toluene, m-xylene, styrene, n-
Gas chromatography analysis was performed using a mixed solution consisting of each reagent of heptane. The mixed solution is quantitatively supplied by a double plunger pump at a rate of about 2 cc / min. At the inlet of the heating furnace 10, nitrogen gas for dilution (5-10
l / min) and led to a reaction tube inside the heating furnace. The heating furnace 10 kept the temperature constant within a range of 300 to 500 ° C., and vaporized the mixed solution to obtain a sample gas. At the outlet of the heating furnace, a cooling nitrogen gas (5 to 10 l / min) was supplied to lower the gas temperature of the vaporized mixed solution and the hydrocarbon partial pressure. Thereafter, the mixed gas (sample gas) is supplied to the sampling passage 1 while keeping the temperature constant at about 150 ° C.
Through to a gas chromatography analyzer.

However, 10 minutes before the gas of the mixed solution coming out of the heating furnace was introduced into the gas chromatography, the valve 8, the sampling passage 1, and the gas chromatography analysis / measurement unit 3 were each connected to the dry nitrogen gas (using the purge line 6). The cleaning gas was purged at a flow rate of 2 l / min. When gas analysis and nitrogen purging were not performed, the valve 4 was opened to discharge the liquid from the discharge path 5 to the outside of the system so that the liquid was not taken into the analyzer.

The same process was performed five times with the above process as one time.
Each result is shown in FIG.

(Comparative Example) As a comparison, a gas analysis was performed in the same manner as in the example except that the purging step for preventing liquid from being taken into the analyzer and the liquid discharging step in the sampling passage were not performed at all. .

 The results are shown in FIG.

Comparing the results of FIGS. 2 and 3, FIG. 2 showing the results obtained by using the analyzer of the present invention shows that good reproducibility of the analysis values is obtained.

On the other hand, as shown in FIG. 3, in the comparative example, the concentration of the analytical value increased every time the test was repeated. In particular, among the reagents used this time, the styrene and m-xylene concentrations having high boiling points were high. The rise is remarkable. As described above, it is difficult to accurately analyze the pyrolysis gas with an analyzer that cannot obtain reproducibility.

<Effects of the Invention> As described above, when the apparatus of the present invention is used, in the related art, it takes time, and there is a problem in performing the automatic analysis. In this case, the following effects can be obtained.

(1) In addition to suppressing the liquefaction of the condensable gas contained in the pyrolysis gas by ordinary means, even in the event of liquefaction, the liquid can be easily discharged to the outside of the system. Since the structure is such that it does not fit into an analyzer such as gas chromatography, reproducibility of analysis data is significantly improved.

(2) By improving the reproducibility of the analysis data, accurate analysis data of the pyrolysis gas can be obtained.

(3) The purging of the sampling passage can be performed more effectively, and the purging time can be shortened.

(4) Due to the above effects, automatic sampling and automatic analysis of the pyrolysis gas become possible, so that the sampling operation of the pyrolysis gas becomes easy and the operation time can be greatly reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an analyzer of the present invention. FIG. 2 is a graph showing the results of the example. FIG. 3 is a graph showing the results of the comparative example. DESCRIPTION OF SYMBOLS 1... Sampling path 2... Gas analyzer 3.
Analytical measuring unit, 4 valve, 5 discharge line, 6 purge line, 7 valve, 8 valve, 9 valve, 10 heating furnace

Claims (1)

(57) [Claims] 1. A sampling path for a gaseous substance containing an easily condensable gas, and an analyzer for the gaseous substance provided downstream of the sampling path, and a lowermost position of the sampling path. Is provided with a discharge path for discharging the condensate of the easily condensable gas condensed in the sampling path from the sampling path, and the discharge path of the sampling path downstream of the lowest point position of the sampling path. At the highest point, the sampling passage and the inlet of the gaseous substance analyzer are connected via a valve, and at a position downstream of the valve at the inlet of the gaseous substance analyzer and close to the valve. A purging line is connected to the sampling passage, and a cleaning nitrogen gas flows to the sampling passage toward the upstream side and the analyzer to the downstream side. Analyzer for gaseous matter containing gas.