CN111624286A - High-temperature ion detection device, detection system formed by same and use method - Google Patents

Abstract

The invention provides a high-temperature ion detection device and a detection system composed thereof and a method of use thereof, and particularly relates to the technical field of gas detection instruments. The high-temperature ion detection device comprises a casing and an ion-type detector. The device includes an ion detector electrode pair, and a gas introduction pipe runs through the shell. One end of the gas introduction pipe near the outlet is provided with a gas outlet, and the other end is provided with a gas inlet. The gas introduction pipe is provided with a heater, and the inside of the gas introduction pipe is provided with The ion detector electrode pair is located downstream of the heater according to the gas flow direction. Two high temperature ion detection devices form a high temperature ion detection system. The invention uses the heater to heat the gas inside the gas introduction pipe to produce chemical ionization of the carbon-containing organic matter, and solves the problem of using hydrogen. By comparing the two detection results, the reliability, sensitivity and stability of the detection method are increased.

Description

A kind of high temperature ion detection device and composed detection system and using method

technical field

The invention belongs to the technical field of gas detection instruments, and in particular relates to a high temperature ion detection device, a detection system composed thereof, and a use method.

Background technique

FID (flame ionization detector, flame ionization detector) uses hydrogen combustion flame to detect the ions generated during the high-temperature combustion of organic matter, so as to realize the detector of organic matter detection. The hydrogen flame ionization detector is composed of a nozzle, an ignition coil, a polarizer, and a collector. Its working principle is that when carbon-containing organic matter is burned in a hydrogen flame, chemical ionization occurs, and the following reactions occur:

When the carrier gas containing organics C _n H _m is ejected from the nozzle into the flame, a cracking reaction occurs to generate free radicals:

C _n H _m → · CH (1)

The generated free radicals react with the excited atomic oxygen or molecular oxygen diffused from outside in the flame as follows:

·CH+O→CHO ⁺ +e (2)

The generated positive ion CHO ⁺ collides with a large number of water molecules in the flame to cause molecular ion reaction:

CHO ⁺ +H ₂ O→H ₃ O ⁺ +CO (3)

The positive ions generated by the reaction are collected on the negative electrode under the action of an electric field, and a weak current is generated, which is amplified to obtain a chromatographic signal. FID is a mass detector for organic analysis. It has high sensitivity, wide linear range, easy to master and wide application range, especially for gas chromatography detectors.

However, the existing FID detector needs to use hydrogen as a heat source, which is inconvenient to carry and has potential safety hazards.

SUMMARY OF THE INVENTION

Aiming at the shortcomings of the existing FID technology, such as potential safety hazards, the present invention provides a high-temperature ion detection device, which is provided with a heater, does not require a hydrogen combustion flame, and directly uses the heater to heat the gas inside the gas introduction pipe to generate carbon-containing organic matter. Chemical ionization solves the problems that the existing hydrogen is inconvenient to carry and has potential safety hazards.

The present invention provides the following technical solutions:

A high-temperature ion detection device includes a casing and an ion detector, one end of the casing is provided with an outlet, the ion detector includes an electrode pair of the ion detector, and a gas introduction pipe is arranged through the casing, One end of the gas introduction pipe close to the outlet is provided with a gas outlet, and the other end is provided with a gas inlet, the gas introduction pipe is provided with a heater, and the heater is used for heating the gas inside the gas introduction pipe. The carbon-containing organic matter produces chemical ionization, the ion detector electrode pair is arranged inside the gas introduction pipe, and the ion detector electrode pair is located downstream of the heater according to the gas flow direction. The present invention does not require a hydrogen combustion flame, directly uses a heater to heat the gas inside the gas introduction pipe to generate chemical ionization of carbon-containing organic matter, and solves the existing problems of inconvenience in carrying hydrogen and potential safety hazards.

Preferably, the ion detector electrode pair includes two plate-shaped first metal electrodes.

Preferably, the ion detector electrode pair includes two second metal electrodes, one of the second metal electrodes is a metal circular tube, the other of the second metal electrodes is a metal rod, and the metal rod is located in the The inside of the metal circular tube is coaxial; the inner diameter of the metal circular tube is 1mm to 20mm, the length is 1mm to 50mm, the outer diameter of the metal rod is 0.1mm to 5mm, the metal circular tube and The metal rod is an electrical conductor resistant to a high temperature of 1000°C.

Preferably, the gap between the inner wall of the casing and the gas introduction pipe is filled with thermal insulation material, and the thermal insulation material is quartz wool. Insulation materials can play the role of heat insulation and heat preservation.

Preferably, the gas introduction pipe is made of quartz, alumina, zirconia or ceramics, the inner diameter of the gas introduction pipe is 0.1 mm to 10 mm, and the wall thickness is 0.1 mm to 5 mm.

Preferably, the outlet is covered with a safety cap, and further includes a temperature detector, which is used to detect the temperature of the gas in the gas introduction pipe, and the heater is electrically connected to the power supply for the heater through a heater wire , the ion detector further comprises an ion detector power supply, a voltage detector and a high resistance; the voltage detector is used to detect the voltage formed by the current generated by the ion detector electrode pair on the high resistance.

Preferably, the heater heats the gas inside the gas introduction pipe to 300-1000°C, the power supply for the heater is a power supply that can output alternating current, pulse or direct current, and the output voltage of the ion detector power supply is direct current , pulse or AC, the voltage peak is 10V to 20kV.

Preferably, the heater is a high-resistance wire, and the high-resistance wire is embedded inside the gas introduction pipe or installed (eg, installed by winding) outside the gas introduction pipe.

Another object of the present invention is to provide a method of using a high-temperature ion detection device. First, the gas introduction pipe is heated, and then the gas to be detected is introduced into the gas inlet. The current signal is detected by an ion detector, and the comparison and integral, and convert to obtain the concentration of substances in the gas corresponding to the heating combustion products. The ion current signal is output to the recorder, and the chromatographic elution curve in which the peak area is proportional to the mass of the component is obtained (the chemical bond of the sample is broken when heated, and a certain amount of positive and negative ions are generated, and the electrode pair (ion detector electrode pair) is added. A certain voltage is applied to form an electric field, which can collect positive ions or negative ions generated by the broken bond of the object to be tested, and the current signal formed by the collected ions will eventually be converted into a corresponding chromatogram response through voltage conversion and signal amplifier. It needs to be calculated by the peak area, and the mass of each component in the sample is proportional to its chromatographic peak area, that is, m _i = f _i *A _i , where m _i is the mass of the component, f _i is the chromatographic peak area, and A _i is current. Several commonly used quantitative methods include normalization method, external standard method and internal standard method, where the formula of normalization method is:

; Since these methods are all existing, other methods will not be expanded in detail.

A high-temperature ion detection system, comprising two sets of high-temperature ion detection devices, wherein one set of high-temperature ion detection devices is used to detect gases containing combustibles, and the other set of high-temperature ion detection devices is used to detect gases without combustibles, Then make the difference between the two test results. By comparing the two detection results, the reliability, sensitivity and stability of the detection method are increased.

beneficial effect

1. The present invention does not require a hydrogen combustion flame, and directly uses a heater to heat the gas inside the gas introduction pipe to produce chemical ionization of carbon-containing organic matter, which solves the problems that the existing hydrogen is inconvenient to carry and has potential safety hazards.

2. Using the high-temperature ion detection device of the present invention for detection can meet the requirements of accuracy, reliability and stability.

3. Using the high-temperature ion detection system of the present invention, the detection results of two high-temperature ion detection devices are compared, so that the reliability, sensitivity and stability of the detection method are increased.

Description of drawings

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

1 is a schematic structural diagram of a high-temperature ion detection device according to Embodiment 1 of the present invention;

2 is a schematic structural diagram of a system assembled by the high-temperature ion detection device according to Embodiment 3 of the present invention;

Fig. 3 is the detection result schematic diagram in embodiment 2;

FIG. 4 is a schematic diagram of the detection results in Example 3. FIG.

Among them, 1. Shell; 2. Outlet; 3. Safety helmet; 4. Gas inlet pipe; 5. Gas inlet; 6. Gas outlet; 7. Heater; 8. Temperature signal line; 9. Power supply for heater; 10 , ion detector electrode pair; 101, high voltage rod; 102, grounding pipe; 11, ion detector power supply; 12, voltage signal output terminal; 13, high resistance; 14, heat insulation material.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, a high-temperature ion detection device includes a casing 1 and an ion detector. One end of the casing 1 is provided with an outlet 2, and the outlet 2 is covered with a safety cap 3. The ion detector includes an ion detector electrode. Pair 10, the ion detector power supply 11, the voltage detector and the high resistance 13, the voltage detector is used to detect the voltage formed by the current generated by the ion detector electrode pair 10 on the high resistance 13; the casing 1 is provided with a gas introduction tube running through it 4. One end of the gas introduction pipe 4 close to the outlet 2 is provided with a gas outlet 6, the other end is provided with a gas inlet 5, the gas introduction pipe 4 is provided with a heater 7, and the inside of the gas introduction pipe 4 is provided with an ion detector electrode pair 10, The ion detector electrode pair 10 is located downstream of the heater 7 according to the gas flow direction. The heater 7 is arranged in the middle of the gas introduction pipe 4, and the heater 7 is a high-resistance wire. The high-resistance wire can be embedded in the gas introduction pipe 4 or wrapped around the outside of the gas introduction pipe 4. In this embodiment, it is selected to be installed in Outside the gas introduction pipe 4, the heater 7 is electrically heated, and is connected to the power supply 9 for the heater through two heater 7 wires. In order to better control the temperature, including setting the temperature and understanding the temperature in real time, a special temperature detector is set to detect the temperature of the gas in the gas introduction pipe 4. The temperature detector is detected by a thermocouple or an infrared temperature detector. When a thermocouple is used The thermocouple can be placed inside the gas introduction pipe 4 or outside the gas introduction pipe 4 through the sleeve, the temperature detector is connected to the controller through the temperature signal line 8, and the controller and the heater are electrically connected with the power supply 9, so that the temperature detector will The temperature change is transmitted to the controller (not shown in the figure, only the temperature signal line 8 is shown in the figure), and the controller controls the heating power supply 9 to work or not to control whether the heater 7 is heated or not. In this heating area (In the gap between the inner wall of the casing 1 and the gas introduction pipe 4) a thermal insulation material 14 is provided. In this embodiment, quartz wool is used as the thermal insulation material 14, which can play the role of thermal insulation and thermal insulation.

Specifically, the gas introduction pipe 4 is made of quartz, alumina, zirconia or ceramics, the inner diameter of the gas introduction pipe 4 is 0.1 mm to 10 mm, and the wall thickness is 0.1 mm to 5 mm.

Specifically, the ion detector electrode pair 10 may be two second metal electrodes or two plate-shaped first metal electrodes; in this embodiment, there are two second metal electrodes, and one second metal electrode is a metal circular tube , the other second metal electrode is a metal rod, the metal rod is located inside the metal circular tube and the two are coaxial; the inner diameter of the metal circular tube is 1mm to 20mm, the length is 1mm to 50mm, and the outer diameter of the metal rod is 0.1mm To 5mm, the metal round tube and metal rod are conductors resistant to high temperature of 1000 ℃. Among them, the metal rod is called the high-voltage rod 101 , and the metal circular tube is called the grounding pipe 102 .

Specifically, the heater 7 heats the gas inside the gas introduction pipe 4 to 300-1000°C, and the heater power supply 9 is a power supply that can output AC, pulse or DC, that is to say, the heater power supply 9 can output AC, Pulse or DC voltage, its output power can be controlled, the output voltage of the ion detector power supply 11 is DC, pulse or AC, that is to say, the ion detector power supply 11 can choose to output AC, DC or pulse voltage according to the needs, and the voltage peak value is 10V to 20kV.

principle:

When the organic compound enters the gas introduction pipe part where the heater 7 is located, chemical ionization is generated at the high temperature of the heater 7, and the ionization generates ions several orders of magnitude higher than the base flow. The weak ion current (10 ^-12 -10 ^-8 A) is amplified by high resistance (10 ⁶ -10 ¹¹ Ω) (the voltage of the high resistance 13 is detected by the voltage detector, and then it passes through the voltage signal output terminal 12 (that is, the output of the amplifier). terminal) output, and can be displayed on the recorder) to become an electrical signal proportional to the amount of organic compounds entering the heater 7, so the organic compounds can be quantitatively analyzed according to the magnitude of the signal.

Example 2

Detect the detection stability of the high temperature ion detection device of Example 1:

Taking methane as an example, _N2 is the carrier gas (30ml/min), the temperature of the heater 7 is set to 600°C, the methane concentration (within 10000ppmv) is selected for detection, and the organic matter is analyzed by the magnitude of the electrical signal.

The test results are shown in Table 1:

Table 1 Measurement results of detection stability of high temperature ion detection device

The line graph prepared according to the data is shown in Figure 3. It can be seen from Figure 3 that the voltage signal (the voltage across the high resistance 13) is basically proportional to the methane concentration, indicating that the high temperature ion detection device can meet the requirements of accuracy, reliability and stability .

Example 3

As shown in Figure 2, a high-temperature ion detection system includes two sets of high-temperature ion detection devices of Embodiment 1, one set of high-temperature ion detection device is used to detect gas containing combustibles, and the other set of high-temperature ion detection device is used for Detect gases that do not contain combustibles, and then compare the two detection results to increase the reliability, sensitivity and stability of the detection method.

_N2 was used as the carrier gas (flow rate was 30ml/min), the temperature of the two high-temperature ion detection devices were both set to 600°C, one set was used to detect the gas containing combustibles (within 10000ppmv), methane was used here, and the other set was used to detect Gas without combustibles (within 10000ppmv), carbon dioxide is used here, and _CO2 is selected as the incombustible gas. The chemical properties of carbon dioxide are inactive, and the thermal stability is very high (only 1.8% decomposes at 2000°C), and it cannot be burned.

The test results are shown in Table 2:

Table 2 Measurement results of high temperature ion detection system

The line graph drawn according to the measurement results is shown in Figure 4. It can be seen from Figure 4 that the voltage signal obtained by the high temperature ion detector for the gas without combustibles (ie CO ₂ ) is weak (almost negligible), so it can be passed through the high temperature ion detector. The difference between the gas containing combustibles and the gas without combustibles is more accurately converted to the concentration of the corresponding substance.

The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited to this. Equivalent replacements or changes to its concept should be included within the protection scope of the present invention.

Claims (10)

1. The utility model provides a high temperature ion detection device, including casing (1) and ion type detector, the one end of casing (1) is equipped with export (2), the ion type detector includes ion detector electrode pair (10), a serial communication port, it has gas inlet pipe (4) to run through in casing (1), the one end that is close to export (2) of gas inlet pipe (4) is equipped with gas outlet (6), the other end is equipped with gas inlet (5), gas inlet pipe (4) are equipped with heater (7), heater (7) are used for making carbonaceous organic matter produce chemical ionization for the gas heating of gas inlet pipe (4) inside, gas inlet pipe (4) inside is equipped with ion detector electrode pair (10), according to the gas flow direction, ion detector electrode pair (10) are located the low reaches of heater (7).

2. A high-temperature ion detection apparatus according to claim 1, characterized in that the ion detector electrode pair (10) comprises two plate-like first metal electrodes.

3. A high temperature ion detection device according to claim 1, wherein the ion detector electrode pair (10) comprises two second metal electrodes, one of the second metal electrodes is a metal circular tube, the metal circular tube is a grounding tube (102), the other second metal electrode is a metal rod, the metal rod is a high voltage rod (101), and the metal rod is positioned inside the metal circular tube and is coaxial with the metal circular tube; the inner diameter of the metal round pipe is 1mm to 20mm, the length is 1mm to 50mm, the outer diameter of the metal rod is 0.1mm to 5mm, and the metal round pipe and the metal rod are high-temperature conductors resistant to 1000 ℃.

4. A high-temperature ion detection apparatus according to claim 1, wherein a heat insulating material (14) is filled between the inner wall of the housing (1) and the gap of the gas introduction pipe (4).

5. A high-temperature ion detection apparatus according to claim 1, wherein the gas introduction tube (4) is made of quartz, alumina, zirconia or ceramics, and the gas introduction tube (4) has an inner diameter of 0.1mm to 10mm and a wall thickness of 0.1mm to 5 mm.

6. A high-temperature ion detection device according to claim 1, wherein the outlet (2) is sleeved with a safety cap (3), and further comprises a temperature detector for detecting the temperature of the gas in the gas inlet pipe (4), the heater (7) is electrically connected with a power supply (9) for the heater through a heater (7) wire, and the ion detector further comprises an ion detector power supply (11), a voltage detector and a high resistance (13); the voltage detector is used for detecting the voltage formed on the high resistance (13) by the current generated by the ion detector electrode pair (10).

7. The high-temperature ion detection apparatus according to claim 6, wherein the heater (7) heats the gas inside the gas introduction pipe (4) to 1000 ℃ and the power supply (9) for the heater is a power supply that can output AC or pulse or DC; the output voltage of the ion detector power supply (11) is direct current, pulse or alternating current, and the voltage peak value is 10V to 20 kV.

8. A high-temperature ion detection device according to claim 1, wherein the heater (7) is a high resistance wire embedded inside the gas introduction pipe (4) or wound outside the gas introduction pipe (4).

9. A use method of the high-temperature ion detection device according to any one of claims 1 to 8, characterized in that, the gas inlet pipe (4) is heated first, then the gas to be detected is introduced from the gas inlet (5), the current signal is detected by the ion detector, and the concentration of the substance corresponding to the heated combustion product in the gas is obtained through comparison and integration and conversion.

10. A high temperature ion detection system, comprising 2 sets of high temperature ion detection devices according to claims 1 to 8, wherein 1 set of high temperature ion detection device is used for detecting gas containing combustible substances, and the other 1 set of high temperature ion detection device is used for detecting gas containing no combustible substances, and then 2 detection results are used for making difference.

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