JPS63286762A - Gas chromatography for analyzing combustible component - Google Patents

Abstract

PURPOSE:To simplify equipment and to facilitate maintenance and inspection by mixing a combustion gas with a gas contg. a known concn. of oxygen, separating the same in a sepn. column and investigating the quantity of a change in the oxygen concn. in accordance with the holding time of the respective gaseous components. CONSTITUTION:A carrier gas 1 of a gas cylinder 2 flows from a flow passage 3 through one side hole 13 of a selector cock 11 to the sepn. column 4. The gas 10 is then filled in the other side hole 12 of the cock 11 when a gaseous sample 10 is injected into the cock 11. The gas 10 is carried to the column 4 by the flow of the gas 1 if the gas 10 is introduced into the gas 1 by alternating the side holes 12, 13 at the point of the time when the pressure on the side hole 12 side attains equal. The respective components in the gas 10 are separated by repeated adsorptions, desorptions, etc., to and from a packing material 5 in the column 4 and emerge from the column 4, the lower boiling components emerging earlier. These components are held mixed with the gas and are entered in this state into a reaction tube 7 where the reaction is effected with the aid of the oxygen and catalyst in the gas 1. As a result, the oxygen concn. in the gas shows the change corresponding to the concn. of the gaseous combustible component relative to time (t). Such change is detected 8 and the quantity of the change is amplified 17, by which the concn. by each component is known.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to gas chromatography for analyzing combustible components.
More specifically, the present invention relates to gas chromatography for combustible component analysis suitable for analyzing combustible components in combustion gas from various engines and combustion devices using a compact and inexpensive device.

[Conventional technology]

Gas chromatography is widely used to analyze the components of organic and inorganic gases in combustion gas generated in engines and combustion equipment. Gas chromatography is an apparatus in which a sample gas is transported by a carrier gas to a separation column, and components in the separated sample gas are detected by a detector.

The detector is generally TCD (thermal conductivity detection type) or FID.
(hydrogen ion detection type) is used.

[Problem that the invention seeks to solve]

These detectors have high accuracy and are sufficient for practical use, but there are problems in making them inexpensive and compact, as described below.

TCD requires a flow path and filament for only carrier gas in the thermal conductivity cell, and also requires a sample gas flow path and filament that is exposed to the carrier gas! , the change in electrical resistance of the filament due to the difference in thermal conductivity between the sample gas and carrier gas is comparatively detected. Tungsten, platinum, etc. are used for the filament.

After the carrier gas normally flows through the carrier gas-only channel of the thermal conductivity cell, it passes through the sample gas injection hole, where it takes in a certain amount of sample gas and flows through the separation column, containing the separated components of the sample gas. flows through the sample gas flow path of the thermal conductivity cell. Therefore, TCD has the disadvantage that the flow path becomes long.

j: In TCD, the carrier gas is He, Ne, which has a significantly higher thermal conductivity than the sample gas, but H is flammable, so it requires expensive equipment and maintenance to ensure safety. However, gas prices for He and Ne are high.

FID applies a high voltage to a hydrogen flame and detects changes in electrical conductivity when a sample gas is mixed with the hydrogen flame.

Since FID uses hydrogen as a combustion fuel, it requires hydrogen supply equipment and safety maintenance and inspection, and requires equipment for carrier gas separately from fuel.

The purpose of the present invention is to solve the problems of the prior art described in
An object of the present invention is to provide a safe gas chromatography for analyzing combustible components that is compact and does not use combustible gas such as H2.

[Means for solving problems]

The present invention provides means for introducing a gas containing combustible components to be analyzed into a 4L separation column together with a carrier gas that does not substantially contain combustible components, and a sample gas discharged from the separation column and separated into components. means for oxidizing the sample gas, means for mixing a predetermined concentration of oxygen into the gas upstream or downstream of the separation column, and a gas after the oxidation reaction between the combustible components in the sample gas and the oxygen. and means for detecting the concentration of combustible components based on the amount of change in the oxygen concentration in the fuel.

[Effect]

In the analysis of gases containing 01 combustible components, such as combustion gases, it is important to quantify the concentration of combustible gases, such as CO1 hydrocarbons. If combustion gas is mixed with gas containing oxygen at a known concentration and separated using a separation column, CO and each hydrocarbon concentration can be determined chemically! A logically equivalent amount of Ot is consumed and becomes a history of Ot concentration changes.

This 0□ concentration change can be detected by an oxygen sensor, and the combustible component concentration can be determined by examining the amount of change in oxygen concentration based on the retention time of each gas component.

Therefore, a mixture of an inert gas and oxygen, air, or the like can be used as the carrier gas, and combustible gas such as H2 is not used, which simplifies the equipment.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the present invention. In FIG. 1, a gas cylinder 2 for supplying a carrier gas 1 is connected to a separation column 4 via a carrier gas flow path 3. The separation column 4 is filled with a packing material 5 for sample gas separation. Separation column 4 is a constant temperature bath 6
It is housed inside and the temperature can be controlled. A reaction tube 7 filled with an oxidation catalyst is arranged downstream of the separation column 4, and this reaction tube 7 is connected to a heater 1 to maintain the catalyst activation temperature.
5 is attached.

A detection section 18 in which a dilute λ sensor 8 is set is installed on the downstream side of the reaction tube 7 . In addition, a switching cock 1 for switching the gas flow path between the side hole 12 and the side hole 13 is provided in the middle of the gas flow path from the gas cylinder 2 to the separation column 4.
) is arranged, and a pressure regulator 14 is installed in the gas flow path between the gas cylinder 2 and the switching cock 1).

FIG. 2 shows a principle diagram of a porous limiting current type oxygen sensor used as the dilute λ sensor 8 in FIG. In FIG. 2, numeral 31 is a cathode, 32 is an anode,
33 is a solid electrolyte consisting of Zr0t-YzOx, 3
4 is an orifice.

In this oxygen sensor, when a current is passed through the solid electrolyte 33,
Oxygen flows into the cathode 31 and is released from the anode 32. Therefore, when a cover in which an orifice 34 is formed is placed over the cathode 31 side, the orifice 34 controls the rate of oxygen inflow, so that even if the voltage is increased, the current remains at a constant value, as shown in FIG. 4(A). This results in a region of saturation. This current is called the limiting current and is proportional to the oxygen concentration. Therefore, the fourth
As shown in Figure (B), when a constant voltage is applied, the oxygen concentration can be measured from the flowing current.

Moreover, FIG. 3 is a perspective view showing a practical sensor. In FIG. 3, a porous alumina substrate 41 is used as an oxygen gas rate limiter instead of the orifice 34 described above, and a cathode 42 made of platinum, a zirconia electrolyte 43, and an anode 44 made of platinum are sequentially disposed on the porous alumina substrate 41. A sensor is formed by stacking layers, and a platinum heater 45 is provided on the lower surface of a porous alumina substrate 41. The sensor shown in FIG. 3 also exhibits the characteristics shown in FIGS. 4(A) and 4(B), and the oxygen concentration in the sample gas can be measured from the value of the current flowing through the sensor.

Next, the operation of the gas chromatography shown in FIG. 1 will be explained.

Gas chromatography uses a constant temperature bath 6 containing a separation column 4.
While the reaction tube 7 and the detection section 18 are heated to a predetermined temperature, the carrier gas 1 is supplied from the gas cylinder 2 via the switching cock 1) at a predetermined pressure and at a constant flow rate. Since a mixture of an inert gas and oxygen is used as the carrier gas, it is common to supply the carrier gas 1 with a gas cylinder 2 filled with a mixture of these gases, but it is also possible to use separate cylinders for oxygen and inert gas. The mixing ratio may be adjusted by attaching a pressure regulator to each.

In this method, even if some impurity gas is contained in the carrier gas, as long as the impurity gas is not a combustible component, it will not substantially affect the measurement, so air can also be used as the carrier gas. In this case, it is necessary to be careful about the environment in which this gas chromatography is used. When using the atmosphere, the atmosphere is pressurized by a pump, and the pressure is adjusted before flowing into the flow path 3. The oxygen concentration in the carrier gas is adjusted upstream of the outlet of the separation column 4, and the oxygen concentration in the carrier gas is equal to the combustible components in the sample gas 10 and the oxygen. To avoid reactions, it is desirable to keep the concentration as low as possible.

Here, a range of 0.0221% to 1% is suitable.

The carrier gas l is supplied from the flow path 3 to the switching cock 1 for introducing the sample.
) flows into the separation column 4 through the hole 13 on one side. When the temperatures of the separation column 4, reaction tube 7, and dilute λ sensor 8 are set to predetermined values while the carrier gas 1 is flowing, the gas chromatography becomes ready for measurement.

The sample gas is analyzed as follows. Switching cock 1
), one side hole 12 of the switching cock 1) is filled with the sample gas 10. The switching cock 1) has a side hole 12 on the sample side and a side hole 13 on the carrier gas side.
The sample gas IO is introduced into the carrier gas 1 by replacing the side holes 12 and 13 when the pressure on the side hole 12 is balanced. The sample gas 10 is carried to the separation column 4 by the flow of carrier gas.

Here, each component in the sample gas 10 is separated by repeating adsorption/desorption, dissolution, and evaporation between it and the packing material 5 in the separation column 4, and generally the low-boiling point components emerge from the separation column 4.

Nitrogen and oxygen in the sample flow together with the carrier gas, and then the inorganic and organic components ride on the carrier gas and are separated over time and exit.

This situation is shown in FIG. 5(A).

These components then enter the reaction tube 7 in a mixed state with a carrier gas. Here, it reacts with oxygen in the carrier gas with the help of a catalyst. This results in the consumption of stoichiometrically equivalent oxygen as shown in the equation below.

1) □＋＋Aoz → Hlo
...(1)CO++AO□-+002
...(2) Ci tlj Ok + (i
+ j/4- k/2) O□→ i Co □
+ j/2) I □0 ... (3)
(fj Ilj Ok: Any combustible component consisting of C, H, and 0) As a result, the oxygen concentration in the carrier gas increases by 4 degrees with respect to time t, as shown in Figure 5 (B). shows a change corresponding to the stoichiometry. By detecting this with the λ sensor 8 and amplifying the amount of change with the amplifier 17, the concentration of the component can be determined.

In order to know the component side concentration according to Figure 5, which change corresponds to which component, or the sensitivity to these concentrations, is
It is necessary to test and investigate in advance. For this purpose, the retention time and phase N sensitivity are verified and determined in advance using a known tester 4.

The output from the amplifier 17 is recorded or processed by a recorder or computer. Note that the combustible gas concentration corresponds to the deviation (change) from the concentration in the carrier gas of 0□ concentration in FIG. 5, and the integrated value of this deviation area corresponds to the concentration of each component in the sample gas.

The concentration output is an Ot conversion value, but if the chemical composition of each component is known, it is converted to the component concentration via equations (1) to (3).

FIG. 6 is a schematic configuration diagram showing a second embodiment of the present invention. The difference in FIG. 6 from the first embodiment shown in FIG. 1 is the method of supplying the carrier gas.

N, , He as a carrier gas up to the separation force ram 4 outlet
, Ar, etc. are supplied, and the sample gas carried by the carrier gas is mixed with oxygen at the front of the reaction tube 7. By this method, the reaction between the combustible gas and oxygen in the separation column 4 is completely eliminated, so that the combustible components in the sample gas are reliably separated and discharged from the separation column 4.
This separated combustible component is mixed with oxygen at a known concentration, which is preferable for improving accuracy. Here, a throttle 27.19 is provided to adjust the mixing ratio of carrier gas and oxygen. In the figure, since the basic structure is the same as that of the first embodiment, parts other than the gas flow path are omitted.

FIG. 7 is a schematic configuration diagram showing a third embodiment of the present invention, and is an example in which the atmosphere is used as the carrier gas.

A filter 20, a heater 21, a reaction tube 22, and a pump 23 are installed upstream of the flow path 3. Reaction tube 22 and heater 2
1 is equipped to burn and remove combustible gas when it is contained in the atmosphere.

Impure gases in the atmosphere directly affect the output of the dilute λ sensor, but since the reactor 22 has a considerably L flow rate compared to the separation column 4, diffusion causes a gradual deviation from the standard in Figure 5(B) (base combustible components in the sample gas can be detected by detecting only sharp changes. This type has the advantage of not requiring a 1.t Yaria gas cylinder, being compact, and easy to carry.

In the case of gas chromatography shown in FIG. 7, the operation and principle are the same as in the first embodiment, so a description thereof will be omitted.

FIG. 8 is a schematic configuration diagram showing a fourth embodiment of the present invention. The fourth embodiment combines the gas chromatography described above and the gas sampling valve 24.

The sample gas 10 is sampled from the cylinder of the engine or the combustor by the gas sampling valve 24 . Therefore, the gas sampling valve 24 and the sample gas flow path 9 are in communication.

In this embodiment, each main body of the gas chromatography may be any one of the first to third embodiments, but in FIG. 8, the first embodiment is applied as an example of each main body of the gas chromatography.

FIG. 9 is a schematic configuration diagram showing a fifth embodiment of the present invention. In the fifth embodiment, a sample gas is sucked by a pump 26 from an exhaust pipe 25 of an engine or a combustor. Each main body of the gas chromatograph may be of any of the first to third embodiments, and in FIG. 9, the one of the first embodiment is used. In addition, the position of the pump 26 may be upstream or downstream of the switching cock 1).

On each side shown here, a reaction tube 7 and a dilute λ sensor 8 are used, but if the dilute λ sensor 8 itself has high catalytic activity, the catalytic oxidation reaction is possible here, so the reaction tube 7 is used. is not necessary. The reactivity 7 is filled with an oxidation catalyst, and as this oxidation catalyst, a porous carrier (Afi□0
A catalyst in which noble metals such as Pt, Pd, and Rh are supported on Pt, Pd, Rh, etc. is preferably used.

Furthermore, the constant temperature bath for the separation column 4 often uses a mechanism for programmatically controlling the temperature.

The examples up to the previous section have been based on a constant temperature, but
The temperature conditions are not limited to these. Furthermore, although there are a wide variety of packing materials to be filled in the separation column 4, it should be selected arbitrarily depending on the type of combustible components to be analyzed.

The analysis method described here can be used in exactly the same manner as long as the sample gas is a combustible gas (for example, fuel supplied to an engine or combustor, or a fuel-air mixture).

In addition, as the carrier gas, inert gas is particularly effective, but air and other gases can be used as long as they do not substantially contain combustible components.

〔Effect of the invention〕

As described above, according to the present invention, the flow path required for analyzing combustible gas can be shortened, and there is no need to use flammable gas such as hydrogen as a carrier gas, so the equipment can be simplified. It has the excellent effect of making maintenance and inspection easy.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention, and FIG.
The figure is a principle diagram of a perforated box limiting current type oxygen sensor that can be used in the present invention, Figure 3 is a thin film limiting current type oxygen sensor that can be used in the present invention, and Figure 4 (A) is the current of the oxygen sensor. Figure 4 (B) is a voltage characteristic diagram, Figure 4 (B) is a current-oxygen concentration characteristic diagram of the oxygen sensor, Figure 5 is a graph showing the component concentration at the outlet of the separation column and oxygen concentration at the outlet of the reaction tube, and Figure 6 is the graph showing the oxygen concentration at the outlet of the reaction tube. A schematic configuration diagram showing the second embodiment, and FIG. 7 is a third embodiment of the present invention.
FIG. 8 is a schematic diagram showing a fourth embodiment of the present invention, and FIG. 9 is a schematic diagram showing a fifth embodiment of the present invention. 1...Carrier gas, 2...Gas cylinder, 3...Gas flow path, 4...Separation column, 5...Filling material, 6... Constant temperature chamber, 7... Reaction tube, 8... Dilute λ sensor, 9... Sample gas flow path, 10... Sample gas, 1)...Switching cock, 12.13...Side hole, 14...Pressure regulator, 15.16.21...Heater, 17...
・Amplifier, 1B...Detection unit, 19.27...Aperture, 20...Filter, 23.26...Pump, 24...・Gas sampling valve, 25...
・Exhaust pipe, 31... cathode, 32... anode, 33... solid electrolyte, 34... orifice, 41... porous Alumina substrate, 42...
- Platinum cathode, 43...zirconia electrolytic chamber, 44...platinum anode, 45...platinum heater.

Claims (5)

[Claims] (1) A means for introducing a gas containing combustible components to be analyzed into a separation column together with a carrier gas that does not substantially contain combustible components, and an oxidation reaction of the sample gas discharged from the separation column and separated by component. means for mixing oxygen at a predetermined concentration into the gas upstream or downstream of the separation column, and oxygen in the gas after an oxidation reaction between the combustible components in the sample gas and the oxygen. 1. A gas chromatography device for analyzing combustible components, comprising means for detecting combustible component concentration based on the amount of change in concentration. (2) The gas chromatography for combustible component analysis according to claim (1), wherein the carrier gas is a mixed gas of an inert gas and oxygen. (3) The gas chromatography for combustible component analysis according to claim (1), wherein the carrier gas is air. (4) The gas chromatography for combustible component analysis according to claim (1), wherein the means for oxidizing the sample gas comprises a reaction tube filled with an oxidation catalyst. (5) The gas chromatography for combustible component analysis according to claim (1), wherein the amount of change in oxygen concentration is detected by a limiting current type oxygen sensor.