JPH0251056A - Detector for ionization of hydrogen flame - Google Patents

Abstract

PURPOSE:To reduce a response time to the detection from the taking of a sample by forming a sample introduction path for introducing a hydrogen flame to the sample separately as a whole independent of a hydrogen introduction path to allow the feeding of the sample into the hydrogen flame in a short time. CONSTITUTION:A sample introduction path is formed separately independent of a hydrogen nozzle 3 as a hydrogen introduction path in such a manner that a capillary 17 for introducing a sample to a hydrogen flame 6 is run through a base 1B of detector 1 to be led directly to a position where the hydrogen flame 6 is formed. In operation, the sample is fed to the hydrogen flame 6 in a short time and components to be measured in the sample receives energy of the hydrogen flame instantaneously to be ionized, thereby enabling the recording of a density of the components to be measured on a photo coder 14 through an amplifying section 13. It should be noted that a response time to the detection from the taking of a sample is only as short as 5msec according to this construction.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a hydrogen flame ionization detection device.

<Prior art> Generally, gases do not have electrical conductivity at room temperature and pressure, but when a sufficient energy source exists to promote ionization of gas molecules, charged atoms or molecules and free electrons When a suitable electric field is applied from the outside, the gas becomes electrically conductive. A flame ionization detection device is an application of such a phenomenon, and is capable of quantitatively analyzing the component to be measured.

As such a hydrogen flame ionization detection device, for example, the one shown in FIG. 8 is known.

(March 1976 Published by Horiba Ltd. rMEX
(Refer to "A-8X20 Series Service Manual").

That is, the hydrogen supplied from the hydrogen supply source 2 to the depressurized interior space of the detector 1 through the hydrogen nozzle 3 mixes with the air supplied to the detector 1 interior space from the auxiliary combustion air supply source 4. This air-fuel mixture is ignited by a spark plug 5 and combusted, forming a hydrogen flame 6 as an energy source necessary to promote ionization of gas molecules.

On the other hand, the collected sample containing components to be quantitatively analyzed flows through a capillary 7 branched from a sample line 15 serving as a sample supply system to a confluence point 3a formed in a hydrogen nozzle 3, mixes with hydrogen, and becomes hydrogen. It is thrown into the hydrogen flame 6 from the nozzle 3. The input amount is adjusted and quantified by the adjustment action of a constant pressure adjustment device IO disposed between the detector 1, the discharge port 8 on the upper part of the detector 1, and the vacuum pump 9 for sucking the sample.

The component to be measured in the sample put into the hydrogen flame 6 burns in the hydrogen flame 6 and causes ionization, and when the flame 6 becomes electrically conductive, a pair of electrodes 11 and 12 facing each other with the flame 6 in between
A minute current proportional to the concentration of the target component ionized by the electric field between the two flows. This minute current is detected as a voltage value via an amplifying section 13 equipped with a high resistance, and is recorded on a photocoder 14. Since the amount of ionization captured by the electrode has a certain correlation with the concentration of the component to be measured, by knowing the voltage value mentioned above, it is possible to quantitatively analyze the unknown concentration of the component to be measured.

Note that the components to be measured that can be quantitatively analyzed by such a hydrogen flame ionization detection device are limited to hydrocarbon compounds.

<Problems to be Solved by the Invention> However, in such a conventional hydrogen flame ionization detection device, the collected sample passes through the capillary 7 branched from the sample line 15 to the confluence formed in the middle of the hydrogen nozzle 3. Since the sample was supplied to the point 3a and mixed with hydrogen at the confluence point 3a and thrown into the flame 6, the above-mentioned voltage value after the sample was collected from the sample collection port 15a of the sample line 15 It takes about 1 second to be detected, and there is a drawback that the response time is slow.

For this reason, for example, intake, compression,
If you try to quantitatively analyze the concentration of the component to be measured, that is, the hydrocarbon compound, in the engine cylinder during each stroke, which cycles through expansion and exhaust in a short period of time, it is extremely difficult to measure it due to the slow response time as described above. Met.

SUMMARY OF THE INVENTION In view of these conventional problems, an object of the present invention is to provide a hydrogen flame ionization detection device in which the detection time is shortened and responsiveness is improved by improving the structure of the sample supply path.

<Means for Solving the Problems> Therefore, the present invention provides a hydrogen flame ionization detection device that detects the ionization of a component to be measured in a sample continuously introduced into a hydrogen flame under reduced pressure. The entire sample introduction passage leading to hydrogen was formed separately from the hydrogen introduction passage.

<Function> In this configuration, since the entire sample introduction passage is formed separately from the hydrogen introduction passage, the sample is thrown into the hydrogen flame in a short time, and the component to be measured in the sample is instantly absorbed into the hydrogen flame. ionization process, shortening the response time from sample collection to detection.

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

In FIGS. 1 to 7 described below, the same elements as those in FIG. 8 are given the same reference numerals to simplify the explanation.

In the figure, the main body of the detector 1 is composed of a base IA and a cylindrical chamber forming member IB with an open bottom and erected on the top surface of the base IA. The hydrogen nozzle 3, which serves as a hydrogen introduction passage through which hydrogen is introduced from the hydrogen supply source 2, is inserted horizontally into the base IA from the side surface of the base IA, and then bent upward at a right angle, so that the The distal end supply port 3b is projected vertically from the distal end supply port 3b and is opened into the inner space of the chamber forming member IB. The air pipe 16 through which air is guided from the auxiliary combustion air supply source 4 is inserted horizontally into the base IA from the side surface of the base IA, and then vertical pipe parts extend upward from a plurality of positions of the horizontal pipe part. from the position around the hydrogen nozzle 3 on the top surface of the base IA to the tip supply port 16.
a is opened into the inner space of the chamber forming member IB. A capillary 17 serving as a sample introduction passage through which a sample containing a component to be quantitatively analyzed is introduced is connected from the bottom of the base IA to the base IA.
It is inserted into a holding member 18 that extends vertically and is installed inside the base IA, and is projected vertically from the upper surface of the base IA, so that the tip supply port 17a is opened at the hydrogen flame 6 forming position. A proximal sample sampling port 17b of the capillary 17 is connected to a sample chamber 20 made of a hollow member 19 outside the base IA.

A sample is supplied into the sample chamber 20 from a sample supply section (not shown) through a supply opening 19a on the periphery.

A suction pipe 23 in which an orifice 21, a constant pressure adjustment device 22, and a vacuum pump 9 are interposed is connected to a discharge port 8 formed on the upper circumference of the chamber forming member IB.

Further, an ignition plug 5 is disposed at the upper part of the chamber forming member IB.

A pair of electrodes 11 and 12 facing each other with the flame 6 in between is arranged within the chamber forming member IB. A terminal of one electrode 11 is connected to one terminal of a power supply 24 , and a terminal of the other electrode 12 is connected to one input part of an OP amplifier 25 of the amplifying section 13 . The other input section of the OP amplifier 25 is grounded. The output section of the OP amplifier 25 is connected to the photocoder 14. The human power line between the terminal of the electrode 12 and the input of the OP amplifier 25 is connected to the output line of the OP amplifier 25 via a resistor 26 . The terminal of the power supply 24 is connected to the output line of an OP amplifier 25 via a resistor 27.

Note that 40 is a meter that displays the pressure within the chamber forming member IB of the detector 1.

In this configuration, the quantitative analysis function for the unknown concentration of the component to be measured is the same as the conventional one.

Introduction of the sample is performed as follows.

The sample in the sample chamber 20 is introduced into the capillary 17 from the sample collection port 17b by reducing the pressure in the chamber forming member IB of the detector 1 by the operation of the vacuum pump 9, and is introduced into the capillary 17 from the tip supply port 17a of the capillary 17. Guided by hydrogen flame 6.

The amount of sample input is quantified by the constant pressure action of the orifice 21 and the constant pressure adjusting device 22.

According to this configuration, the capillary 17 that guides the sample to the hydrogen flame 6 passes through the base IB of the detector l and is guided directly to the hydrogen flame 6 formation position, so that the entire sample introduction passage can be used as a hydrogen introduction passage. Since the hydrogen nozzle 3 is formed separately from the hydrogen nozzle 3, the sample is thrown into the hydrogen flame in a short time, and the components to be measured in the sample instantly receive the energy of the hydrogen flame and are ionized, causing the amplification section 13 to be ionized. via photocoder 14
It becomes possible to record the concentration of the component to be measured.

Incidentally, according to the above configuration, the response time from sample collection to detection is as short as about 5 msec.

On the other hand, the photocoder 14 is capable of following and recording short-term responses.

Therefore, for example, when quantitatively analyzing the concentration of a component to be measured, that is, a hydrocarbon compound, in an engine cylinder during each short cycle of intake, compression, expansion, and exhaust from an automobile engine, the above-mentioned method can be used. Because the response time is fast, measurements can be made easily and with high accuracy.

Here, as mentioned above, if the response time from sample collection to detection is as short as about 5 msec, the detector 1
It is affected by fluctuations in the pressure (negative pressure) applied within the chamber forming member IB, that is, by pulsations caused by the rotation of the vacuum pump 9. Therefore, in this embodiment, by interposing the orifice 21 and the constant pressure adjusting device 22 between the detector 1 and the vacuum pump 9, it is possible to control the pressure in the chamber forming member IB of the detector 1 to be constant. It is said that

Further, according to the above-mentioned hydrogen flame ionization detection device, since the device is mainly composed of a detection section, an amplification section, and a vacuum pump section, it has the advantage of being compact and easy to carry.

Furthermore, the tip supply port 17a of the capillary 17 can be installed without any problem even in a narrow space.

Next, another embodiment of the present invention is shown in FIG.

In this embodiment, a capillary 28 provided separately from the hydrogen nozzle 3 is guided to the hydrogen flame 6 through the inside of the hydrogen nozzle 3.

That is, the vertical part of the hydrogen nozzle 3 on the base IA of the detector (1) is extended downward to open at the bottom surface of the base IA.

The capillary 28 is inserted into the hydrogen nozzle 3 through the opening of the hydrogen nozzle 3 opened at the bottom of the base IA, and the tip supply port 28a is opened at the tip supply port 3b of the hydrogen nozzle 3.

Note that a sealing member 29 is provided at the opening of the hydrogen nozzle 3 opened at the bottom surface of the base IA to maintain airtightness within the nozzle 3.

Needless to say, this configuration also provides the same functions and effects as the previous embodiment, and in particular, since the capillary 28 is guided to the hydrogen flame 6 using the inside of the hydrogen nozzle 3, the base IA There is no need to separately provide an insertion section dedicated to the capillary, and the configuration can be simplified.

In each of the above embodiments, as one method for shortening the response time from sample collection to detection, the sample collected from the sample collection port should be rapidly introduced into the hydrogen flame 6 (the detector 1 The inside of the chamber forming member IB is placed under reduced pressure.

As a result, a phenomenon may occur in which the hydrogen flame 6 in the chamber forming member IB of the detector 1 is disturbed as the pressure within the chamber forming member IB decreases, and for this reason, the amount of the component to be measured introduced into the hydrogen flame 6 may be disturbed. Stable ionization is hindered, making accurate measurement difficult.

Further, when the pressure inside the chamber forming member IB becomes less than a predetermined value, a situation may occur in which the hydrogen flame 6 misfires.

Therefore, in order to form a stable hydrogen flame 6 even under reduced pressure conditions in the chamber forming member IB of the detector 1, it is preferable to provide a stabilizing member for the hydrogen flame 6 above the hydrogen flame 6.

3 to 5 show examples of this stabilizing member.

That is, in the embodiment shown in FIG. 3, a circular plate-shaped stabilizing member 30 having a circular throttle opening 30a in the center is horizontally disposed and fixed in the upper part of the chamber forming member IB. There is. The stabilizing member 30 may have a wall thickness of about several mm, and is made of a material having heat resistance and corrosion resistance. Further, the diameter of the throttle opening 30a is approximately 1/4 of the inner diameter of the chamber forming member IB.

In the embodiment shown in FIG. 4, in the upper part of the chamber forming member IB,
A stabilizing member 31 having a circular aperture 31a in the center and a substantially spherical lower surface is disposed and fixed.

In the embodiment shown in FIG. 5, in the upper part of the chamber forming member IB,
A cone-shaped stabilizing member 32 is arranged so that the top of the cone is located on the center line of the tip supply port 3b of the hydrogen nozzle 3, and is suspended and supported on the inner surface of the earthen wall of the chamber forming member IB using the mounting legs 32b. are doing.

In this case, the air suction path due to negative pressure is the stabilizing member 3
2 and the inner peripheral surface of the chamber forming member IB.

According to such hydrogen flame stabilizing members 30, 31, 32,
Since the area where negative pressure is directly applied to the hydrogen flame 6 can be reduced, phenomena such as lifting of the hydrogen flame 6 can be prevented, and even under reduced pressure where the pressure inside the chamber forming member IB is -650 mmHg, for example, stable hydrogen can be generated. The flame 6 is maintained, stable ionization of the measurement target component introduced into the hydrogen flame 6 is achieved, and accurate measurement is possible. Furthermore, it is possible to prevent the hydrogen flame 6 from misfiring.

Furthermore, in each of the above embodiments, the sample is the cabin 1J1.
Since the configuration is such that the sample is directly introduced into the hydrogen flame 6 through 7 and 28, if the change in sample pressure inside the sample chamber 20 is small,
Accurate measurement is possible, but if the pressure changes suddenly and significantly, the amount of sample introduced changes in accordance with the change, making it impossible to perform accurate measurement.

Therefore, it is preferable to provide a sample quantification device in which a constant amount of sample is always introduced into the hydrogen flame 6.

FIGS. 6 and 7 show an embodiment of this sample quantification device.

That is, in the embodiment shown in FIG. 6, another capillary 33 is provided that branches off from the vicinity of the sample chamber 20 of the capillary 17, and a check valve 34 is provided at the tip of this branched capillary 33.

The check valve 34 is configured to open when the pressure inside the sample chamber 20 becomes higher than atmospheric pressure, and close when the pressure becomes lower than the atmospheric pressure.

According to this configuration, when the pressure in the sample chamber 20 becomes higher than atmospheric pressure, the check valve 34 opens, and an amount of sample corresponding to the high pressure is released to the atmosphere via the branch capillary 33. Further, when the pressure inside the sample chamber 30 becomes lower than atmospheric pressure, the check valve 34 is closed and the release of the sample to the atmosphere is stopped.

In the embodiment shown in FIG. 7, an electromagnetic on-off valve 35 is provided at the tip of the branch capillary 33, and a pressure sensor 3 is provided to detect the pressure at the branch part of the branch capillary 33.
6, and a control circuit 37 that controls opening and closing of the electromagnetic on-off valve 35 based on the detection signal output from the pressure sensor 36.
and

According to this configuration, when the pressure inside the sample chamber 20 is higher than atmospheric pressure, the electromagnetic on-off valve 35 is controlled to open based on the detection signal output from the pressure sensor 36, and the amount of sample corresponding to the high pressure is controlled to open. is released into the atmosphere via the branch capillary 33. Further, when the pressure inside the sample chamber 20 is lower than atmospheric pressure, the electromagnetic on-off valve 35 is controlled to be closed based on the detection signal output from the pressure sensor 36.

As described above, when the sample pressure in the sample chamber 20 suddenly and significantly changes, the sample is released into the atmosphere according to the change, so the change in the amount of sample introduced can be avoided. The sample to be measured flows at high speed.
Accurate measurement is possible even under conditions where pressure changes occur rapidly.

Therefore, for example, it is possible to easily quantitatively analyze hydrocarbon compounds, which are components to be measured during the compression and exhaust cycles in which the pressure increases during each cycle of suction, compression, expansion, and exhaust in an automobile engine.

<Effects of the Invention> As explained above, according to the hydrogen flame ionization detection device of the present invention, the entire sample introduction passage is formed separately and independently from the hydrogen introduction passage, so that the sample can be exposed to hydrogen in a short time. It can be put into a flame and the components to be measured in the sample can be instantaneously ionized by the energy of the hydrogen flame, so the response time from sample collection to detection can be shortened.

As a result, for example, the suction, compression,
The quick response time mentioned above makes it easy and accurate to quantitatively analyze the concentration of hydrocarbon compounds, which are the components to be measured within the engine cylinder during each stroke, which cycles through expansion and exhaust in a short period of time. Be able to measure.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing one embodiment of the hydrogen flame ionization detection device according to the present invention, Fig. 2 is a system diagram showing another embodiment, and Figs. 3 to 5 are the same hydrogen flame ionization detection device as above. A system diagram showing an example in which a hydrogen flame stabilizing member is provided in the device; FIGS. 6 and 7 are a system diagram showing an example in which a sample quantification device is provided in the hydrogen flame ionization detection device described above, and FIG. is a system diagram of a conventional hydrogen flame ionization detection device. 1...Detector 3...Hydrogen nozzle 6...Hydrogen flame 9...Vacuum pump electrode 13...Amplification section
17, 2 Li 17a, 28a...Tip supply port sample collection port 23...Suction tube 228a...Tip supply port 5...Ignition plug 11.12...8...Capillar 17b... 4... Power supply patent applicant Nissan Motor Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 3

Claims (1)

[Claims] In a hydrogen flame ionization detection device that detects the ionization of a component to be measured in a sample continuously introduced into a hydrogen flame under reduced pressure, the entire sample introduction passage leading the sample to the hydrogen flame is made separate and independent from the hydrogen introduction passage. A hydrogen flame ionization detection device characterized by the following: