Hydrogen-free catalytic quantifying device for semi-volatile organic compounds

Abstract

The utility model discloses a hydrogen-free catalytic quantifying device for semi-volatile organic matters. The hydrogen-free catalytic quantifying device comprises a reactor and a thermocouple signal detecting and processing unit, a catalyst unit for catalytically oxidizing semi-volatile organic matters is arranged in the reactor; a second thermocouple and a third thermocouple are respectively arranged at a semi-volatile organic matter inlet and a semi-volatile organic matter outlet of the catalyst unit; and the thermocouple signal detection processing unit is electrically connected with the second thermocouple and the third thermocouple and is used for detecting and calculating the thermal potential difference between the second thermocouple and the third thermocouple. According to the device, the semi-volatile organic matters are completely catalyzed and oxidized through a catalyst in a high-temperature oxidizing atmosphere taking air as a main body, and the concentration quantification of the semi-volatile organic matters in the gas is realized through thermal monitoring according to the complete oxidizing reaction heat of the organic matters.

Description

Technical Field

[0001] The utility model relates to the technical field of semi-volatile organic compounds (SVOCs) quantitative analysis, in particular to a semi-volatile organic compounds hydrogen-free catalytic quantitative device. Background Art

[0002] Semi-volatile organic matter generally refers to substances with weak volatility, insoluble in water, easily soluble in organic solvents, with a boiling point of 170-350°C and a vapor pressure of 10 -7 A large class of compounds with a pH between 0.1 and 0.1 mmHg.

[0003] Compared with volatile organic compounds (VOCs), semi-volatile organic compounds are more difficult to degrade and exist longer. Most semi-volatile organic compounds are oily liquids that tend to persist in the air, water, soil and other environments, can be transmitted over long distances, and most importantly, have certain toxicity and bioaccumulation effects.

[0004] The existing technologies for quantitative detection of semi-volatile organic compounds are:

[0005] The patent specification with the publication number CN115901660A discloses a method, system and application for quantitative analysis of semi-volatile components in mixed gases based on infrared spectroscopy. The patented technology prepares saturated steam of semi-volatile components by the supersaturation-condensation method, and tests with an infrared spectrometer to collect its spectral data. Specifically: establish the relationship between the concentration of the saturated steam of the target semi-volatile component and its absorbance, obtain the infrared absorption standard spectrum of the saturated steam of the target semi-volatile component, and establish a mixed gas measurement model after collecting the infrared absorption standard spectrum of each required component in the mixed gas to be tested; perform infrared spectral detection on the mixed gas to be tested to obtain a detection infrared spectrum, calculate the detection infrared spectrum and the mixed gas measurement model to obtain the concentration of the semi-volatile component, and realize the quantitative analysis of the concentration of the semi-volatile component in the mixed gas and the rapid quantitative detection of substances under emergency conditions.

[0006] The patent specification with publication number CN111435127A discloses an online analysis system for organic matter in the air, which adopts a three-way thermal desorption (dual-way sampling and one-way cold focusing) system with low-temperature (-120℃~room temperature) external heat exchange refrigeration and a three-way chromatographic column with split / non-split injection (one pre-column and two chromatographic columns with different properties) and a dual ion / photon detector (adaptive large-span concentration switching) as the main analysis system, and uses a calibration system of direct injection multi-point calibration (same as experimental calibration method) and sampling tube injection quality control to perform a comprehensive analysis of volatile / semi-volatile organic matter in the air. Utility Model Content

[0007] The utility model provides a semi-volatile organic matter hydrogen-free catalytic quantitative device, which can quantitatively analyze the content of the semi-volatile organic matter in the gas to be tested.

[0008] A semi-volatile organic matter hydrogen-free catalytic quantitative device, comprising a reactor and a thermocouple signal detection and processing unit;

[0009] A catalyst unit for catalytically oxidizing semi-volatile organic matter is provided in the reactor, and a second thermocouple and a third thermocouple are respectively provided at the semi-volatile organic matter inlet and outlet of the catalyst unit;

[0010] The thermocouple signal detection processing unit is electrically connected to the second thermocouple and the third thermocouple, and is used to detect and calculate the thermoelectric potential difference between the second thermocouple and the third thermocouple.

[0011] In one embodiment, the thermocouple signal detection processing unit includes a second ADC / MCU and an instrumentation operational amplifier, and the instrumentation operational amplifier is connected to the second thermocouple, the third thermocouple and the second ADC / MCU.

[0012] In one embodiment, the semi-volatile organic compound hydrogen-free catalytic quantitative device further includes a heating component, which is disposed upstream of the second thermocouple and is used to preheat the semi-volatile organic compound to a specified temperature.

[0013] In one embodiment, the heating assembly and the second thermocouple are electrically connected to form a control interlock.

[0014] In one embodiment, the semi-volatile organic compound hydrogen-free catalytic quantitative device further includes a first thermocouple.

[0015] In one embodiment, the heating component, the first thermocouple and the second thermocouple are arranged in sequence along the flow direction of the semi-volatile organic gas.

[0016] In one embodiment, the heating assembly and the first thermocouple are electrically connected to form a control interlock.

[0017] In one embodiment, the semi-volatile organic matter hydrogen-free catalytic quantitative device further includes a first PWM control unit and a first ADC / MCU, the first PWM control unit is connected to the heating component and the first ADC / MCU, and the first ADC / MCU is also connected to the first thermocouple.

[0018] In one embodiment, a heat storage body is arranged between the first thermocouple and the second thermocouple.

[0019] In one embodiment, the semi-volatile organic compound hydrogen-free catalytic quantitative device further includes a cooling unit and an air extraction pump.

[0020] In one embodiment, the reactor outlet is connected to a cooling unit and a vacuum pump in sequence.

[0021] In one embodiment, the semi-volatile organic compound hydrogen-free catalytic quantitative device further comprises a flow meter for reflecting the gas flow rate, and the flow meter is connected to the vacuum pump to form a control interlock.

[0022] In one embodiment, the vacuum pump is connected to the flow meter through the second PWM control unit and the first MCU to form a control interlock.

[0023] In one embodiment, the cooling unit includes a cooling coil and a cooling fan for blowing the cooling coil, and the cooling coil is provided with fins. Of course, the cooling coil can also be a long metal heat dissipation pipe, as long as the purpose of reducing the gas in the pipe to the target temperature can be achieved, in which case the fins can be selectively not required according to actual conditions.

[0024] In one embodiment, a temperature detection unit is provided at the outlet of the cooling unit, and the temperature detection unit is connected to the cooling fan via the second MCU to form a control interlock.

[0025] Compared with the prior art, the utility model has the following beneficial effects:

[0026] The utility model utilizes semi-volatile organic matter to completely catalytically oxidize through a catalyst in a high-temperature oxidation atmosphere dominated by air, and realizes quantitative concentration of semi-volatile organic matter in the gas through thermal monitoring according to the heat of complete oxidation reaction of the organic matter. Among them, thermal monitoring uses a twin-compensation structure dual thermocouple (i.e., the second thermocouple and the third thermocouple) to monitor the thermoelectric potential difference caused by the temperature difference of the quantitative airflow at the inlet and outlet of the high-temperature catalytic oxidation reactor (e.g., 400-500°C), and can quantify the concentration of semi-volatile organic matter according to the corresponding calorific value of the oxidation reaction of the semi-volatile organic matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of the hydrogen-free catalytic quantitative device for semi-volatile organic compounds of Example 1. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0029] Example 1

[0030] See also Figure 1The semi-volatile organic matter hydrogen-free catalytic quantitative device of this embodiment includes a thermocouple signal detection and processing unit 5 and a reactor 18, a cooling unit 6 and an air pump 7 connected in sequence. The cooling unit 6 can prevent the temperature of the gas entering the air pump 7 from being too high, causing the air pump 7 to fail to work normally. The outside of the reactor 18 can be wrapped with an insulation layer 14 to make the internal temperature measurement more accurate. The reactor 18 can be connected to an organic waste gas source. The organic waste gas source will produce organic waste gas containing semi-volatile organic matter, the main component of which is air. Under the action of the air pump 7, the organic waste gas has flowed through the reactor 18, the cooling unit 6 and the air pump 7. A catalyst unit 4 is provided in the reactor 18. When the organic waste gas flows through the catalyst unit 4, a complete catalytic oxidation reaction occurs, and heat is released at the same time, so that a temperature difference is formed at the inlet and outlet of the semi-volatile organic matter of the catalyst unit 4. This temperature difference will be detected by the second thermocouple 2 and the third thermocouple 3 arranged at the inlet and outlet of the semi-volatile organic matter of the catalyst unit 4 and reflected by the thermoelectric potential difference. For example, when the second thermocouple 2 and the third thermocouple 3 are S-type platinum-rhodium thermocouples, the 300-600°C graduation table is as follows (unit: mV):

[0031] 0 10 20 30 40 50 60 70 80 90 300 2.323 2.414 2.506 2.599 2.692 2.786 2.88 2.974 3.069 3.164 400 3.26 3.356 3.452 3.549 3.645 3.743 3.84 3.938 4.036 4.135 500 4.234 4.333 4.432 4.532 4.632 4.732 4.832 4.933 5.034 5.136 600 5.237 5.339 5.442 5.544 5.648 5.751 5.855 5.96 6.064 6.169

[0032] It can be seen that in this working temperature range, the thermocouple voltage increases by about 9-10μV for every degree Celsius temperature rise.

[0033] The thermocouple signal detection processing unit 5 is electrically connected to the second thermocouple 2 and the third thermocouple 3, and is used to detect and calculate the thermoelectric potential difference between the second thermocouple 2 and the third thermocouple 3. After obtaining the thermoelectric potential difference between the second thermocouple 2 and the third thermocouple 3, the temperature difference at the inlet and outlet of the catalyst unit 4 can be calculated, and then the semi-volatile organic matter can be quantified based on the relationship between the theoretical value of the adiabatic temperature rise of the complete catalytic oxidation of the semi-volatile organic matter and the content of the semi-volatile organic matter. 3 Adiabatic temperature rise of complete catalytic oxidation at concentration:

[0034] Organic matter Temperature rise(℃) Trimethylbenzene 37.2 Methylstyrene 31.7 Methylphenol 31.1 Triethylbenzene 34.2 benzoic acid 24.0 Naphthalene 36.5

[0035] Therefore, during quantitative analysis, the temperature rise caused by the semi-volatile organic matter before and after complete catalytic oxidation by the catalyst unit can be obtained based on the detected thermoelectric potential difference between the second thermocouple 2 and the third thermocouple 3. When the type of semi-volatile organic matter to be quantified is known, the concentration of semi-volatile organic matter in the gas to be measured can be converted based on the theoretical relationship between the specific concentration of semi-volatile organic matter and the adiabatic temperature rise of complete catalytic oxidation using the actual temperature rise result obtained above.

[0036] In order to more accurately reflect the detection results, the thermocouple signal detection processing unit 5 includes a second ADC / MCU 52 and an instrumentation operational amplifier 51, and the instrumentation operational amplifier 51 is connected to the second thermocouple 2, the third thermocouple 3 and the second ADC / MCU 52. The instrumentation operational amplifier 51 can amplify the detection signals of the second thermocouple 2 and the third thermocouple 3 by low and / or high magnification, and then transmit them to the second ADC (analog-to-digital converter) / MCU (microprocessor) 52.

[0037] Most of the organic waste gas corresponding to semi-volatile organic matter corresponds to high-temperature baking, incomplete combustion and other working conditions. The gas temperature is relatively high, mostly between 130 and 300 ° C. In order to reduce the temperature change hysteresis caused by the heat capacity of the catalyst and the measurement error caused thereby, the semi-volatile organic matter hydrogen-free catalytic quantitative device of this embodiment also includes a heating component 15 and a first thermocouple 1. The heating component 15 and the first thermocouple 1 are both arranged in the reactor 18, and the heating component 15, the first thermocouple 1 and the second thermocouple 2 are arranged in sequence along the flow direction of the semi-volatile organic matter. The heating component 15 is used to preheat the semi-volatile organic matter to a specified temperature, and can specifically be an electric heating wire, etc. The heating component 15 and the first thermocouple 1 are electrically connected to form a control interlock. Specifically, the first thermocouple 1 is connected to the first ADC / MCU17, and the first PWM control unit 16 is connected to the heating component 15 and the first ADC / MCU17. The first ADC / MCU17 receives the temperature detection signal transmitted by the first thermocouple 1, and sends a control signal to the first PWM control unit 16 according to the difference between the actual temperature and the preset temperature. The first PWM control unit 16 receives the control signal sent by the first ADC / MCU17 to adjust the working state of the heating component 15 (such as heating power, etc.).

[0038] After the gas is preheated, a heat storage body 13 (specifically, heat storage ceramic particles, etc.) is further provided between the first thermocouple 1 and the second thermocouple 2 in the reactor 18. The thermal resistance of the heat storage body 13 is utilized to make the temperature change curve smooth.

[0039] Considering the actual engineering application, the object of quantitative analysis of semi-volatile organic matter is usually the source of organic waste gas. For this reason, the present embodiment provides a cooling unit 6 to facilitate the collection and discharge of tail gas (because the organic pollutants have been completely catalytically oxidized and harmlessly treated in the reactor 18).

[0040] In order to conveniently and more accurately measure and calculate the concentration of semi-volatile organic matter in organic waste gas, the semi-volatile organic matter hydrogen-free catalytic quantitative device of this embodiment also includes a flow meter 8 for reflecting the gas flow rate, and the flow meter 8 is connected to the vacuum pump 7 to form a control interlock. Furthermore, the vacuum pump 7 is connected to the flow meter 8 through the second PWM control unit 12 and the first MCU11 to form a control interlock. The first MCU11 receives the flow signal transmitted by the flow meter 8, and accordingly sends a control signal to the second PWM control unit 12 to adjust the working state of the vacuum pump 7, such as the suction volume. The vacuum pump 7 can be driven by a brushless motor, connected to the flow meter 8, and the speed of the vacuum pump 7 is adjusted according to the flow data, so that the vacuum pump 7 runs at the set suction volume.

[0041] The cooling unit 6 may be an air-cooled unit, including a cooling coil 61 and a cooling fan 63 for purging the cooling coil 61. In the present embodiment, the cooling coil 61 may be provided with fins 62 (if the temperature of the exhaust gas after passing through the cooling unit 6 is lower than the preset target temperature without the fins, the fins may not be required). A temperature detection unit 9 is provided at the outlet of the cooling unit 6, and the temperature detection unit 9 is connected to the cooling fan 63 through the second MCU 10 to form a control interlock. The temperature of the exhaust gas after passing through the cooling unit 6 may be set to a target of not exceeding 50°C (which is beneficial to protect the normal operation of the vacuum pump 7, and excessively high gas temperature may damage the vacuum pump 7). In this case, the second MCU 10 receives the temperature signal data collected by the temperature detection unit 9, processes and feedbacks it, and sends a control signal to the cooling fan 63 to adjust the working state such as the cooling air volume.

[0042] Example 2

[0043] The semi-volatile organic compound hydrogen-free catalytic quantitative device of this embodiment is basically the same as that of Embodiment 1, with the main difference being that the first thermocouple 1 and the heat storage body 13 are not provided, and the heating component 15 is directly electrically connected to the second thermocouple 2 to form a control interlock. The method of forming the control interlock can refer to the control interlock connection relationship between the heating component 15 and the first thermocouple 1 in Embodiment 1.

[0044] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A semi-volatile organic compound hydrogen-free catalytic quantitative device, characterized in that: It comprises a reactor (18) and a thermocouple signal detection and processing unit (5); A catalyst unit (4) for catalytically oxidizing semi-volatile organic matter is provided in the reactor (18), and a second thermocouple (2) and a third thermocouple (3) are respectively provided at the semi-volatile organic matter inlet and outlet of the catalyst unit (4); The thermocouple signal detection processing unit (5) is electrically connected to the second thermocouple (2) and the third thermocouple (3) and is used to detect and calculate the thermoelectric potential difference between the second thermocouple (2) and the third thermocouple (3).

2. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 1, characterized in that: The thermocouple signal detection processing unit (5) comprises a second ADC / MCU (52) and an instrument operational amplifier (51), wherein the instrument operational amplifier (51) is connected to the second thermocouple (2), the third thermocouple (3) and the second ADC / MCU (52).

3. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 1, characterized in that: The semi-volatile organic matter hydrogen-free catalytic quantitative device further comprises a heating component (15), which is arranged upstream of the second thermocouple (2) and is used to preheat the semi-volatile organic matter to a specified temperature.

4. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 3, characterized in that: The heating assembly (15) and the second thermocouple (2) are electrically connected to form a control interlock.

5. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 3, characterized in that: The semi-volatile organic matter hydrogen-free catalytic quantitative device further comprises a first thermocouple (1); The heating component (15), the first thermocouple (1) and the second thermocouple (2) are arranged in sequence along the flow direction of the semi-volatile organic gas; The heating assembly (15) and the first thermocouple (1) are electrically connected to form a control interlock.

6. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 5, characterized in that: The semi-volatile organic matter hydrogen-free catalytic quantitative device further comprises a first PWM control unit (16) and a first ADC / MCU (17); the first PWM control unit (16) is connected to the heating component (15) and the first ADC / MCU (17); the first ADC / MCU (17) is also connected to the first thermocouple (1).

7. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 5, characterized in that: A heat storage body (13) is arranged between the first thermocouple (1) and the second thermocouple (2).

8. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 1, characterized in that: The semi-volatile organic matter hydrogen-free catalytic quantitative device further comprises a cooling unit (6) and an air pump (7); The outlet of the reactor (18) is connected to a cooling unit (6) and a vacuum pump (7) in sequence.

9. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 8, characterized in that: The semi-volatile organic matter hydrogen-free catalytic quantitative device further comprises a flow meter (8) for reflecting the gas flow rate, and the flow meter (8) is connected to the vacuum pump (7) to form a control interlock; The air extraction pump (7) is connected to the flow meter (8) via the second PWM control unit (12) and the first MCU (11) to form a control interlock.

10. The hydrogen-free catalytic quantitative device for semi-volatile organic compounds according to claim 8, characterized in that: The cooling unit (6) comprises a cooling coil (61) and a cooling fan (63) for blowing the cooling coil (61), and fins (62) are provided on the cooling coil (61); A temperature detection unit (9) is provided at the outlet of the cooling unit (6), and the temperature detection unit (9) is connected to the cooling fan (63) via the second MCU (10) to form a control interlock.

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