JPS6020144A - Method for analyzing trace component in gas - Google Patents

Abstract

PURPOSE:To automate an analyzing stage by spraying an evaporated refrigerant controlled to a specified temp. so as to meet the characteristic of the gaseous sample to be supplied into a sample thickening pipe to said pipe and capturing selectively the trace component. CONSTITUTION:While a sample thickening pipe 32 is first heated, a carrier gas is passed through a feed port 36 to remove the adsorbed material in an adsorbent 35 in the case of analyzing the trace component in a gaseous sample. A liquid refrigerant is then ejected from an ejecting nozzle 29 to the refrigerant flow passage 30b of a heating cylinder 30 and the evaporated refrigerant of a specified temp. evaporated by heating is sprayed to the U-pipe part 32a of the pipe 32. The specified temp. of said refrigerant is controlled by a heater 34 of the heating cylinder 30 so as to meet the characteristic of the gaseous sample. When the part 32a is cooled to the specified temp., the gaseous sample is supplied through the port 36 and the trace component in the gaseous sample is adsorbed to the adsorbent 35 and is thereby thickened. When the required amt. of the sample is thickened, the supply of the liquid refrigerant is stopped and the part 32a is heated by a heater 38 to desorb the trace component.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for analyzing textile components in gas.

[Conventional technology]

Gases such as nitrogen, hydrogen, and argon are increasingly found to contain ppb level impurities in the semiconductor manufacturing industry, and an effective analysis method for this purpose is now required.

Conventionally, when analyzing trace components such as impurities in gas,
After passing the gas through a cooling trap to cool and concentrate impurities, six substances were analyzed at t4 by analysis methods such as gas chromatography.

However, this method requires manual labor to introduce the refrigerant into the sample condensation tube, remove it, and heat the sample concentrator tube after removal, making automation difficult.

In this analysis method, when cooling the cold trap, liquid nitrogen (-196°C), liquid argon (-186°C
), dry ice-methanol (approximately -80°C), liquid nitrogen-ethanol (-130°C), etc.
An organic solvent bath (e.g., 15°C) was used.

Liquefied gas baths are used to analyze impurities in high-purity gases and to analyze single components in the atmosphere, and are suitable for analyzing impurities in helium, for example. However, in this liquefied gas bath, for analysis of impurities in nitrogen, argon, and oxygen, cooling il! Since the temperature is fixed at the elli point of the refrigerant, there is a problem in that the main component liquefies within the cooling trap, making it impossible to successfully collect the target impurity component.

On the other hand, in an organic solvent bath, when raising the temperature for desorption,
Because combustible gas evaporates and is dangerous, and dry ice and nitrogen also evaporate, supplying and discharging through pipes is not recommended.
However, there was a problem that it was not suitable for automated analysis.

[Purpose of the invention]

This invention was made to solve these conventional problems, and involves spraying a vaporized refrigerant into a sample concentrating tube at a constant temperature according to the characteristics of the sample gas supplied therein. As it cools down, (1) eye +11J
The purpose of the present invention is to provide a method for analyzing trace components in gas that can selectively collect only trace components such as impurities, and (2) that can automate the analysis. It is something.

[Structure of the invention]

In this invention, a carrier gas is passed through a sample fQ thin tube while heating it, and an adsorbent filled in the tube adsorbs @
There is an aging process for removing cormorant substances, a cooling process for cooling the sample concentration tube by spraying a vaporized refrigerant controlled at a constant temperature, and a cooling process for supplying sample gas to the sample concentration tube while continuing to cool it. A concentration step in which trace components in the sample gas are adsorbed and concentrated using the filled adsorbent; a desorption step in which the sample concentration tube is heated to desorb the trace components adsorbed by the adsorbent; and a carrier is added to the sample concentration tube. This is a method for analyzing trace components in gas, which consists of an analysis step in which trace components desorbed from an adsorbent are sent to a separation column through gas and the amount NL is measured.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on a component analyzer, that is, a gas chromatograph, shown in FIGS. 1 to 7.

Figure 1 shows the aging process in the example, Figure 2 shows the cooling process, Figure 3 shows the concentration process, Figure 4 shows the desorption process, and Figure 5 shows the analysis process. Fig. 6 is an imitation of Fig. 1 to Fig. 5) and Fig. 7 is a cross-sectional view of the component concentrating device. It is an enlarged view of the main part.

First, when the tA composition of the gas chromatograph is determined by 19,
1 is carrier gas o, a population, 2, 3.4° 5, 22
6.7.8 is an impurity removal trap, 9 is a reversal valve, 10.18.19 is a resistance pipe, 11 is a first hexagonal switching cock (hereinafter referred to as the 1st cock), 12 is a second hexagonal valve. 13 is a first four-way switching valve (hereinafter referred to as the first valve); 14 is a second four-way switching valve (hereinafter referred to as i:ij 2 valve); 15
．． 16 is an injection port, 17 is a separation column, and 20 is a detector for gas chromatography.

21 is the supply port for the test ASF gas, 23 is the flow meter, 24 Har
tic Quantity control jt, 25, 26 honeytle valve, 2T is a buffer tank to prevent backflow of air, A is a trace component concentrator, p is a pressure gauge, 28 is a sealed oven, which is inert gas and slightly lower than outside air. It is pressurized to prevent air and moisture from entering. Incidentally, each of the above-mentioned constituent elements is connected by a pipe.

The trace component concentrating device A has the configuration shown in FIGS. 6 and 7. That is, the device A includes a liquid refrigerant jet nozzle 29, a liquid refrigerant heating cylinder 30 connected by fitting the jet nozzle 29, and a liquid refrigerant heating cylinder 30 connected by fitting the jet nozzle 29, which is heated by the heating cylinder 30. - It is composed of a Fa passage pipe 31 for vaporized refrigerant, and a sample 1 + contraction pipe 32 inserted through this flow pipe 31.

The jet nozzle 29 and the heating cylinder 30 have a jet nozzle 29
Temperature sensor insertion holes 29 a and ' 30 a are provided which communicate with the cold algae flow path 30 b of the force multiplier cylinder 30 . Reference numeral 33 indicates a temperature sensor, that is, a pair of heat sensors inserted through the insertion holes 2ga and 30a, and is installed facing the U-shaped tube portion 32a of the sample concentration tube 32. This thermocouple 33 detects l1 degrees of the vaporized refrigerant heated and vaporized in the heating cylinder 30, and the detection signal is inputted to the first heating temperature control device outside the area. 34 is a heater for the heating cylinder 30, and its heating temperature is 1 fj vs. 3
3, J:, the detection No. 113 is manually controlled by the first heating control device.

The flow pipe 31 is configured such that the vaporized refrigerant flows around the inserted sample concentration pipe 32 and is discharged from the flow branch pipe 31a.

The sample concentration tube 32 is a single glass tube formed into a U-shape.
It is formed by bending it, and the U-shaped tube part 32a at the tip
The inside is filled with an adsorbent 35 such as molecular sieve or silica gel that adsorbs trace components in the gas. 36 is a sample gas supply port, and 37 is also an outlet. 38
is a heater installed around the U-shaped tube portion 32a of the sample concentration tube 32, and 39 is a temperature sensor, that is, a thermocouple, for detecting the heating temperature tx by the heater. It is inserted into the CENTUS duplex 40 so as to face the U-shaped tube portion 32a. Heater 38
The heating temperature is detected by a thermocouple 39 and a second
It is fed back to the heating temperature control device and controlled by this. 41 is a storage case of the trace component concentrator A.

The operation of this device A will be explained as follows.

First, from the jet nozzle 29, the refrigerant flow path 3 of the heat cylinder 30
The liquid refrigerant spouted to 0b is heated and vaporized there, resulting in a constant temperature of vaporization cooling θ1 (as a result, U of the sample concentration tube 32
It is sprayed onto the tube portion 32a.

The constant temperature referred to here is the first heating temperature control ζ1 (1 device i
: It is one quality controlled by j. That is, the temperature of the vaporized refrigerant detected by the thermocouple 33 is fed back to the first heating temperature control device, thereby controlling the temperature to a constant temperature. ! It is held by eight cylinders 30 of heaters 34. This l)+il i is set in advance according to the characteristics such as state changes of the sample gas.
This is the temperature at which only the 1m component, that is, the impurity component, can be selectively collected.

When the U-shaped tube section 32a is cooled to a constant temperature by the blown vaporized refrigerant, when a sample gas is supplied into the U-shaped tube section 32a from the supply section 36 at a predetermined flow rate, trace components in the sample gas are , is adsorbed by the adsorbent 35 and concentrated. Then, the sample gas with trace components adsorbed passes through the flow pipe 31 and is discharged from the flow branch pipe 31a.

When the concentration of the ventricle h() is completed, the supply of sample gas and liquid refrigerant is stopped, and when the U-shaped tube f'fls 32a is heated by the heater 38, adsorption/f'( 11 (component (J de λ°1).

Ibi: ; When the carrier gas is supplied from the sample gas supply port 36, the concentrated breeze component is taken out.

"21: Force 11ζ from self-heater 38? The crystal 1 is fed back to the heating temperature detected by the thermocouple 39 or the second heating temperature control 1:ei ii','(
As a result, the temperature was maintained at a constant temperature by the heater 38, which was controlled at 2 liJ degrees.

Next, each step of the aging step, cooling step, concentration step, desorption step, and analysis step will be explained using a gas chromatograph equipped with the above-mentioned (14) functions.

(1) Aging process (1st stage) In this process, the U-shaped tube part 32a of the sample concentration tube 32 is heated (for example, 300 to 340°C), and a zero gas (for example, I (e gas) is introduced and the adsorbed substance adsorbed by the adsorbent 35 is removed.

That is, the zero gas purified through the impurity removal trap 8 is introduced into the sample concentration tube 32 through the first valve 13 and the second tank 12, and is discharged through the second tank 12 again into the buffer tank 2T. On the other hand, the carrier gas purified through the impurity removal trap 6 passes through the circuit shown by the broken line, that is, the first tank 11 and the second tank 1.
2. It passes through the first column 11, the separation column 17, and is sent to the detector 20.

(2) Cooling step (FIG. 2) In this step, a vaporized refrigerant controlled at a constant temperature is sprayed onto the U-shaped tube portion 32a of the sample concentration tube 32 to cool it.

That is, the circuit of the concentrator A is made into a closed circuit as shown by the dashed line in FIG. 2, and the liquid refrigerant,
For example, liquid nitrogen is ejected and heated in the heating cylinder 30 to become a vaporized refrigerant, thereby cooling the U-shaped tube portion 32a to a certain level J', for example -1301:.

At this time, the sample gas is supplied to the regulating valve 22, the Takigawa control valve 24, the first valve 13, and the second valve as shown by the two-dot chain line.
The liquid is sent to the buffer tank 27 through the tank 12. The purified key tria gas passes through the wrap 6, passes through the first column 11, the resistance tube 10, and the first column 11, and then passes through the separation column 17 and the second column, as shown by the broken line.
After passing through valve 14, it is sent to detector 20. Ten thousand,
The zero gas purified by the impurity removal trap 8 is discharged through the first valve 13 and the needle valve 25, as shown by the thick solid line.

In this cooling step, the temperature of the vaporized refrigerant detected by the thermocouple 33 is constantly fed back to the first heating temperature control device, thereby controlling the heating temperature by the heater 34 of the heating cylinder 30. . Therefore, the temperature of the vaporized refrigerant can be set and controlled in advance to a humidity that matches the characteristics of the sample gas so that the main component of the sample gas does not liquefy.

(3) Concentration process (Figure 3) In this process, the sample concentration tube 32 cooled in the cooling process is
Further, while the cooling is continued, a sample gas is supplied, and one component therein is adsorbed and concentrated by the adsorbent 35.

That is, the sample concentration tube 32 is heated at a constant temperature of t14 degrees (for example, -1
For example, 100 tn
t/min sample gas for a certain period of time (e.g. 10 minutes)
By introducing co, co2. cIJ,,
One minute component of the liquid is adsorbed onto the λi absorbing agent 35.

At this time, the sample gas sequentially passes through the first valve 13, the second tank 12, the sample concentration tube 32, and the second tank 12, as shown by the dashed line, and is released into the pan 7 tank 2T. The carrier gas purified after passing through the impurity removal trap 6 passes through a first tank 11, a second tank 12, a first tank 11, and a separation column 17, as shown by the broken line.
The signal is sent to the detector 20. On the other hand, the zero gas purified by the impurity removal trap 8 is released through the first valve 13 and the needle valve 25, as shown by the thick solid line.

(4) Desorption step (Fig. 4 1) In this step, the sample concentration tube 32 was heated and adsorbed]1
11. Attach and detach the copying amount reed.

That is, the circuit of the zero compression device A is made into a closed circuit as shown by the dashed line in FIG.
is heated with a heater 38 (e.g. 250 to 300°C),
CO, CO□, C in the sample gas adsorbed by the adsorbent 35
Removes trace components such as IT.

At this time, the purified carrier gas passes through the impurity 1 removal trap 6 and is transferred to the first tank 11. as shown by the broken line.
44'ti'J'+: Yes 10, after passing through the first tank 11, separation column 17, and second valve 14, it is sent to the detector 20. On the other hand, the zero gas purified by the impurity removal trap 8 is transferred to the first valve 13, as shown by the solid line.
It passes through the second tank 12 and is discharged into the buffer tank 27.

(5) Analysis step (Figure α5) In this step, carrier gas is passed through the sample concentration tube 32, and the sensitive components desorbed from the adsorbent 35 are sent to the separation column 17, where they are separated and measured.

That is, as shown by the broken line, the carrier gas purified by the impurity removal trap 6 is introduced into the sample concentration tube 32 from the opposite direction to the sample gas in the concentration step, and the desorbed fine M component is sent to the separation column 1γ. . At this time, in order to reduce the adverse effect on the detector 20 due to sudden pressure changes, the second valve 14 is switched for a certain period of time (for example, 30 seconds) and the pressure change is transferred to the resistance tube 18 that causes the same pressure loss as the detector 20. send. After that, the switch is made based on the 1 input and the second valve 14, and the finely crushed components are separated in the separation column 1γ, and then sent to the detector 2.
0 and measure.

At this time, the zero gas purified by the impurity removal trap 8 is discharged into the buffer tank 2T through the entire first valve 13, as shown by the thick solid line.

On the other hand, the carrier gas purified by the impurity removal trap 7 is sent to the detector 20 through the entire second valve 14, as shown by the dashed line.

〔Effect of the invention〕

As explained above, according to the present invention, there are five steps: aging step, cooling step, concentration step, desorption step, and analysis step.
In addition, in the cooling process, a vaporized refrigerant controlled at a constant temperature according to the characteristics of the sample gas is sprayed into the sample concentration tube. (1) The main components in the sample gas are not liquefied. (2) There is no risk of flammable gas being generated during the introduction of refrigerant into the sample concentration tube, removal, and heating of the sample concentration tube after removal, making it possible to selectively collect only trace components. This has the effect of automating the process.

[Brief explanation of the drawing]

Figures 1 to 5 are configuration diagrams of a gas chromatograph for explaining the present invention in detail, in which Figure 1 shows the aging process in the example, Figure 2 shows the same cooling process, and Figure 3 shows the same process. The concentration process, Figure 4, also shows the desorption process, Figure 5.
6 is a sectional view of the concentrator shown in FIGS. 1 to 5, and FIG. 7 is a sectional view of Vll-1 in FIG. 6. 32... λ contraction tube near the sample 35... Adsorbent

Claims (1)

[Claims] While heating the sample #shrinkage tube, pass a carrier gas through it, and use the adsorbent filled in it for 1! The aging process removes the adsorbed substances that have adhered to the sample concentration tube, the cooling top-pressing process involves spraying a vaporized refrigerant controlled at a constant temperature onto the sample concentration tube, and the sample gas is added to the sample concentration tube while continuing the cooling process. a concentration step in which the trace components in the sample gas are adsorbed and concentrated by the adsorbent filled therein; and a desorption step in which the sample concentration tube is heated to desorb the trace components adsorbed by the adsorbent. 14) A method for analyzing gI content in a gas, which consists of an analysis step in which a carrier gas is passed through a condenser tube to send trace components desorbed from an adsorbent to a separation column for separation and measurement.