OCEC analysis system and its use method

Abstract

The present invention discloses an OCEC analysis system and a method for using the same. The system includes a sample furnace, the sample furnace includes a furnace tube, a filter membrane arranged in the furnace tube, and a heating device arranged outside the furnace tube to heat the filter membrane. A heat preservation shell is arranged outside the furnace tube corresponding to the heating device to seal and wrap the heating device in the heat preservation shell. A sealed space is provided between the heat preservation shell and the heating device. An air inlet pipe and an air outlet pipe are connected to the heat preservation shell to fill the sealed space with oxygen-free or hypoxic gas, so that the heating device is heated in the oxygen-free or hypoxic space. The OCEC analysis system and the method for using the same are beneficial to prolonging the life of the heating device and improving the heating efficiency of the heating device.

Description

Technical Field

[0001] The invention relates to an environmental quality monitoring instrument, in particular to an OCEC analysis system and a use method thereof. Background Art

[0002] The carbonaceous component in atmospheric aerosol usually accounts for 10-70% of the mass concentration of atmospheric fine particles and is an important component of atmospheric fine particles. It can be divided into three categories: organic carbon (OC), elemental carbon (EC) and carbonate carbon (CC). OC refers to a mixture containing hundreds of organic compounds (such as aliphatic, aromatic, acid, etc.), which mainly comes from emissions from primary combustion processes, biological emissions, and emissions from gaseous organic pollutants participating in photochemical reactions and gas-particle conversion processes. EC usually refers to an amorphous carbon with very low crystallinity that is directly emitted after incomplete combustion of carbon-containing substances such as fossil fuels or biomass. CC mainly exists in coarse particles of soil and coal mine fly ash. Its mass concentration is much smaller than OC and EC, so it is generally ignored.

[0003] Carbonaceous components in atmospheric aerosols can have an impact on global climate, atmospheric visibility, and human health. EC, as the main optical absorption component in atmospheric aerosols, can not only absorb light in the entire band from infrared to ultraviolet, but also deepen the color of particles, making some particles that originally did not absorb radiation or absorbed less light absorb light, thereby increasing positive radiation forcing. In addition, carbonaceous aerosols can also act as condensation nuclei to change the concentration and life span of cloud droplets in the atmosphere, indirectly affecting the earth's radiation balance. In terms of visibility, the strong absorption of light by EC and the scattering of light by OC can significantly reduce the visibility of the regional atmosphere. In terms of human health, most of the carbonaceous components in aerosols exist in fine particles (0.1-1μm), so they can easily enter the lungs through human respiration, destroy the structure and function of the lungs, and cause chronic respiratory diseases. Therefore, studying the carbonaceous components of atmospheric aerosols is of great significance and has become a hot topic in the field of environmental monitoring today.

[0004] The detection principle of the carbonaceous components of atmospheric aerosols based on the thermo-optical method is: the particulate matter samples in the air are collected by using the filter membrane, and then the filter membrane is heated step by step in an oxygen-free environment with He carrier gas. At this time, OC in the particulate matter is volatilized (and part of it is carbonized to form cracked carbon), and then the carrier gas is changed to He / Ox and the temperature is continued to be raised step by step. During this period, it is believed that EC is oxidized and decomposed and escapes. The OC and EC escaping from the membrane are then converted into CO2 through the catalytic oxidation of MnO2, and finally quantified. During the entire thermal decomposition process, a laser beam is always used to track the change in the blackness of the quartz membrane, that is, its transmitted light (or reflected light) gradually increases with the carbonization of OC and gradually weakens with the oxidation and decomposition of EC. When the transmission (or reflection) light intensity is restored to the initial transmission (or reflection) light intensity, this moment is considered to be the division point of OC and EC concentrations, that is: the carbonaceous component analyzed by thermal analysis before this point is OC, and the carbonaceous component detected after that is EC. During the operation of the OCEC analysis system, the sample furnace needs to heat up and cool down quickly, and the maximum temperature is as high as 850-900℃. In the prior art, the technical solutions disclosed in application numbers CN201010249182.8 and CN201510501754.X all use fans to dissipate heat and cool down in order to achieve the purpose of rapid heating and rapid cooling of the sample furnace heating wire. Specifically, a fan with a large air volume is set at the bottom or side of the sample furnace, and the outer shell of the sample furnace corresponding to its air outlet is hollowed out to form an air duct from top to bottom. The fan blows out the heat in the sample furnace through the air duct for heat dissipation. In this way, the heating wire is directly exposed to the air, and the heating wire is prone to oxidation in a high-temperature environment with air. The heating wire undergoes a sharp change in multiple temperature gradients, which causes great loss to the heating wire and greatly reduces the life of the heating wire. In addition, during the heating and heating process, since the air duct is set on the sample furnace, the heat of the sample furnace is accelerated to be transferred to the outside, and the heat in the sample furnace will be dissipated, affecting the heating efficiency. Summary of the invention

[0005] The invention provides an OCEC analysis system and a method for using the same, so as to prolong the life of a heating device and improve the heating efficiency of the heating device.

[0006] The present invention provides an OCEC analysis system, comprising a sample furnace, the sample furnace comprising a furnace tube, a filter membrane arranged in the furnace tube, and a heating device arranged outside the furnace tube to heat the filter membrane, characterized in that a heat preservation shell is arranged outside the furnace tube corresponding to the heating device, so as to seal and wrap the heating device in the heat preservation shell, a sealed space is provided between the heat preservation shell and the heating device, and an air inlet pipe and an air outlet pipe are connected to the heat preservation shell, so as to fill the sealed space with oxygen-free or low-oxygen gas, so that the heating device is heated in the oxygen-free or low-oxygen space.

[0007] Furthermore, an intake valve is provided at the intake end of the intake pipe, the input end of the intake valve is connected to an oxygen-free or low-oxygen source, and the oxygen-free or low-oxygen gas enters the sealed space through the intake pipe; an exhaust valve is provided at the exhaust end of the outlet pipe, and the exhaust valve has an exhaust port.

[0008] Furthermore, the insulation shell is made of a metal plate and an insulation board, and the insulation board is arranged closely against the inner wall of the metal plate.

[0009] Furthermore, a temperature measuring element is provided on the furnace tube near the filter membrane, and a suction pump is provided at the output end of the exhaust valve.

[0010] Furthermore, the heating device adopts a heating wire wound around the outer circumference of the furnace tube at a position corresponding to the filter membrane, and a high-temperature resistant insulating tube is arranged outside the heating wire.

[0011] Furthermore, both ends of the furnace tube extend out of the insulation shell, a laser is provided at one end of the furnace tube, a spectrometer is provided between the laser and the filter membrane, a first detector for receiving the laser reflected by the filter membrane and the spectrometer and detecting the laser light intensity is provided on the furnace tube near the spectrometer, a second detector for receiving the laser passing through the filter membrane and detecting the laser light intensity is provided on the other end of the furnace tube, and a sampling tube is connected to the furnace tube between the second detector and the filter membrane.

[0012] Furthermore, the two ends of the furnace tube extend out of the insulation shell respectively, one end of the furnace tube is provided with a first laser, a first beam splitter and a first detector, and the other end of the furnace tube is provided with a second laser, a second beam splitter and a second detector. A part of the laser light emitted by the first laser passes through the first beam splitter, the filter membrane and the second beam splitter and enters the second detector, and another part is reflected back by the filter membrane and then reflected by the first beam splitter and enters the first detector; a part of the laser light emitted by the second laser is reflected by the second beam splitter, passes through the filter membrane and reflects by the first beam splitter and then enters the first detector, and another part is reflected back by the filter membrane and then reflected by the second beam splitter and enters the second detector.

[0013] Furthermore, the heat-insulating shell includes a first shell section and a second shell section, a sealed space is formed between the first shell section and the heating device, and an oxidation furnace is provided between the second shell section and the furnace tube.

[0014] The present invention also provides a method for using the above OCEC analysis system. Before the heating device starts heating, oxygen-free or low-oxygen gas is filled into the sealed space through the air inlet pipe, and the air in the sealed space is exhausted through the air outlet pipe.

[0015] The present invention also provides a method for using the above OCEC analysis system. During cooling, oxygen-free or low-oxygen gas is firstly filled into the sealed space to cool to an intermediate temperature, and then air is filled into the sealed space to cool to a specified temperature.

[0016] The present invention also provides a method for using the above-mentioned OCEC analysis system. When the temperature detected by the temperature measuring element during the cooling process is greater than a preset value, the air intake valve is controlled to switch to an anaerobic or low-oxygen source to fill in anaerobic or low-oxygen gas, the exhaust port of the exhaust valve is controlled to be opened, and the anaerobic or low-oxygen gas enters the sealed space through the air intake pipe, and the heat in the sealed space is discharged from the exhaust port of the exhaust valve through the air outlet pipe; when the temperature detected by the temperature measuring element drops below the set value, the air intake valve is controlled to switch to the air inlet, and the anaerobic or low-oxygen source inlet is closed, and air is drawn into the sealed space by a suction pump, thereby dissipating the heat in the sealed space through the air outlet pipe.

[0017] Beneficial effects of the present invention:

[0018] The OCEC analysis system of the present invention forms a sealed space between the heat preservation shell and the heating device by arranging a heat preservation shell that seals and wraps the heating device outside the furnace tube, and fills the sealed space with oxygen-free or low-oxygen gas through the air inlet pipe, and the air in the sealed space is discharged from the air outlet pipe, so that the sealed space is in an oxygen-free or low-oxygen space, and the heating device is heated in the oxygen-free or low-oxygen space, thereby preventing the heating device from being oxidized at high temperature, thereby improving the service life of the heating device. In addition, the heat preservation shell seals and wraps the heating device in the heat preservation shell, which can play a role in gathering the heat of the heating device, which is beneficial to reducing the heat loss of the heating device, thereby improving the heating efficiency of the heating device.

[0019] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 is a structural diagram of an OCEC analysis system according to Embodiment 1 of the present invention;

[0022] Figure 2 is a schematic diagram of the structure of an OCEC analysis system according to a second embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of the structure of an OCEC analysis system according to Embodiment 3 of the present invention;

[0024] Figure 4 It is a structural diagram of an OCEC analysis system according to a fourth embodiment of the present invention.

[0025] Legend: sample furnace 1, furnace tube 11, filter membrane 12, heating device 13, insulation shell 2, sealed space 20, air inlet pipe 21, air outlet pipe 22, air inlet valve 23, exhaust valve 24, temperature measuring element 14, suction pump 3, laser 4, spectrometer 41, first detector 42, second detector 43, sampling tube 5, output tube 6, oxidation furnace 15, carbon dioxide sensor 16, control valve 17, first laser 401, first spectrometer 402, first detector 403, second laser 404, second spectrometer 405, second detector 406, first shell section 201, second shell section 202, manganese dioxide oxidant 151, heater 152, gas pipe 153. DETAILED DESCRIPTION

[0026] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0027] Embodiment 1

[0028] like Figure 1 As shown, an embodiment of the present invention provides an OCEC analysis system, including a sample furnace 1, the sample furnace 1 including a furnace tube 11, a filter membrane 12 arranged in the furnace tube 11, and a heating device 13 arranged outside the furnace tube 11 to heat the filter membrane 12. An insulation shell 2 is arranged outside the furnace tube 11 corresponding to the heating device 13, so as to seal and wrap the heating device 13 in the insulation shell 2, and a sealed space 20 is provided between the insulation shell 2 and the heating device 13. An air inlet pipe 21 and an air outlet pipe 22 are connected to the insulation shell 2 to fill the sealed space 20 with oxygen-free or low-oxygen gas, so that the heating device 13 is heated in the oxygen-free or low-oxygen space, thereby preventing the heating device 13 from being oxidized at high temperature, thereby improving the service life of the heating device 13.

[0029] The OCEC analysis system of the present invention forms a sealed space 20 between the heat preservation shell 2 and the heating device 13 by arranging a heat preservation shell 2 that seals and wraps the heating device 13 outside the furnace tube 11, and fills the sealed space 20 with oxygen-free or low-oxygen gas through the air inlet pipe 21, and the air in the sealed space 20 is discharged from the air outlet pipe 22, so that the sealed space 20 is in an oxygen-free or low-oxygen space, and the heating device 13 is heated in the oxygen-free or low-oxygen space, thereby preventing the heating device 13 from being oxidized at high temperature, thereby improving the service life of the heating device 13. In addition, the heat preservation shell 2 seals and wraps the heating device 13 in the heat preservation shell 2, which can play a role in gathering the heat of the heating device 13, which is conducive to reducing the heat loss of the heating device 13, thereby improving the heating efficiency of the heating device 13.

[0030] An air inlet valve 23 is provided at the air inlet end of the air inlet pipe 21, and the input end of the air inlet valve 23 is connected to an oxygen-free or low-oxygen source, and the oxygen-free or low-oxygen gas enters the sealed space 20 through the air inlet pipe 21. An exhaust valve 24 is provided at the exhaust end of the air outlet pipe 22, and the exhaust valve 24 has an exhaust port for the air in the sealed space 20 to be discharged when the oxygen-free or low-oxygen gas is filled into the sealed space 20. The oxygen-free gas is preferably nitrogen, which has low cost and can meet the use requirements. In addition, the oxygen-free gas can also be selected from the helium used in this system, but the cost is relatively high. It can be understood that the oxygen-free gas is not limited to nitrogen and helium, and other non-flammable gases can also be selected, as long as the oxygen-free or low-oxygen safe heating space can be achieved.

[0031] In this embodiment, in order to ensure the temperature requirements of the analysis process, the insulation shell 2 is made of a metal plate and an insulation board, and the insulation board is arranged close to the inner wall of the metal plate, wherein the insulation board can be made of calcium silicate material; in order to further improve the insulation performance, the metal plate is wrapped with insulation cotton for heat insulation protection.

[0032] In order to improve the heat dissipation performance of the cooling process of this system, a step-by-step heat dissipation method is adopted. In the high-temperature heat dissipation stage, oxygen-free or low-oxygen gas is filled into the sealed space 20 for cooling, and in the low-temperature heat dissipation stage, air is filled into the sealed space 20 for cooling. The critical value of the high-temperature heat dissipation stage and the low-temperature heat dissipation stage is approximately the middle value between the highest temperature and the cooling to the specified temperature. The high-temperature heat dissipation stage and the low-temperature heat dissipation stage are only for comparison, and their critical values ​​are not limited to the middle value between the highest temperature and the cooling to the specified temperature. For example, when cooling from the highest temperature of 830°C to the specified 30°C, the critical value of the high-temperature heat dissipation stage and the low-temperature heat dissipation stage is preferably 400°C, but is not limited to 400°C, and can also be 300°C, 320°C, 450°C, 500°C and other temperature values. It can be understood that the cooling process of this system can also be cooled by filling the sealed space 20 with oxygen-free or low-oxygen gas throughout the whole process, such as using nitrogen for cooling throughout the whole process, but it will increase the consumption of nitrogen and the cost is relatively high.

[0033] In this embodiment, a temperature measuring element 14 is provided on the furnace tube 11 near the filter membrane 12 to detect the temperature at the filter membrane 12. A suction pump 3 is provided at the output end of the exhaust valve 24 to discharge the heat in the sealed space 20. It can be understood that the suction pump 3 can also be provided on the outlet pipe 22 connected between the heat preservation shell 2 and the exhaust valve 24 to discharge the heat through the exhaust port of the exhaust valve 24. When the temperature detected by the temperature measuring element 14 is 850-400°C during the cooling process, the air intake valve 23 is controlled to switch to the oxygen-free or low-oxygen source to fill the oxygen-free or low-oxygen gas, and the exhaust port of the exhaust valve 24 is controlled to be opened, and the oxygen-free or low-oxygen gas enters the sealed space 20 through the air intake pipe 21, and the heat in the sealed space 20 is discharged from the exhaust port of the exhaust valve 24 through the air outlet pipe 22. In order to speed up the cooling speed, the oxygen-free or low-oxygen gas can be cooled before being filled into the sealed space 20. When the temperature detected by the temperature measuring element 14 drops below 400°C, the air inlet valve 23 is controlled to switch to the air inlet, and the oxygen-free or low-oxygen source inlet is closed, and air is drawn into the sealed space 20 through the suction pump 3, so that the heat in the sealed space 20 is dissipated through the outlet pipe 22. The above-mentioned step-by-step heat dissipation method uses refrigerated nitrogen to cool down in the high-temperature stage, and switches to an air extraction type heat dissipation mode in the semi-high temperature stage, which greatly improves the life of the heating device 13 and reduces the gas consumption of oxygen-free gases such as nitrogen. At the same time, since there is no heat dissipation fan, the volume of the system structure is greatly reduced, and the noise generated during use is reduced. When dissipating heat, due to the sealing of the insulation shell 2, the gas enters from the air inlet pipe 21 and exits from the air outlet pipe 22, the gas volume is concentrated, the loss is small, the heat dissipation efficiency is greatly improved, and it is conducive to the rapid cooling of the system.

[0034] In this embodiment, the heating device 13 uses a heating wire wound around the outer periphery of the furnace tube 11 corresponding to the position of the filter membrane 12, which has the advantages of simple structure, low cost and easy implementation. In order to withstand high temperatures and avoid short circuits caused by winding, a high-temperature resistant insulating tube is arranged outside the heating wire, and the high-temperature resistant insulating tube can be a quartz fiber tube, a high-silicon fiber tube or a ceramic fiber tube.

[0035] In this embodiment, both ends of the furnace tube 11 extend out of the heat preservation shell 2, a laser 4 is provided at one end of the furnace tube 11, a beam splitter 41 is provided between the laser 4 and the filter membrane 12, a first detector 42 is provided at the laser reflection end of the beam splitter 41, and a second detector 43 is provided at one end of the furnace tube 11 opposite to the laser 4. The laser 4 emits a laser, which is irradiated on the filter membrane 12 through the beam splitter 41, a part of the laser is received by the second detector 43 after passing through the filter membrane 1 and the light intensity of the laser is detected, and another part of the laser is received by the first detector 42 after being reflected by the filter membrane 12 and the beam splitter 41 and the light intensity of the laser is detected.

[0036] A sampling tube 5 is connected to the furnace tube 11 between the laser 4 and the filter membrane 12, and the sampling tube 5 is connected to the air inlet valve 23 for switching the input of sample gas, helium or helium-oxygen gas. An output tube 6 is connected to the furnace tube 11 near the second detector 43, and the output tube 6 is connected to one input end of the exhaust valve 24, and the outlet pipe 22 is connected to the other input end of the exhaust valve 24. When the exhaust valve 24 is switched to its exhaust port is open, oxygen-free or hypoxic gas can be filled into the sealed space 20 and air can be exhausted. When the exhaust valve 24 is switched to the outlet pipe 22 and the suction pump 3 are open, air can be filled into the sealed space 20 for cooling. When the exhaust valve 24 is switched to the output pipe 6 and the suction pump 3 are open, the sample gas can be filled into the furnace tube 11, and the sample gas passes through the filter membrane 12 in the furnace tube 11, and is discharged from the suction pump 3 through the exhaust valve 24, and the particulate matter in the sample gas is intercepted and enriched by the filter membrane 12. The gas outlet pipe 22 and the output pipe 6 are connected to the suction pump 3 through the exhaust valve 24, so that the furnace tube 11 can draw sample gas or the sealed space 20 can draw air for cooling by sharing the suction pump 3, thereby reducing the system manufacturing cost.

[0037] In this embodiment, the output end of the furnace tube 11 is connected to an oxidation furnace 15, and the oxidation furnace 15 is located between the filter membrane 12 and the second detector 43. The output end of the oxidation furnace 15 is connected to a carbon dioxide sensor 16. A control valve 17 is provided between the output end of the oxidation furnace 15 and the input end of the carbon dioxide sensor 16, so that the air tightness of the OCEC analysis system can be checked by closing the control valve 17 and other valves. If the air tightness of the OCEC analysis system is not good, the ambient air flows into the furnace tube 11, which will affect the detection of organic carbon and elemental carbon. By closing the control valve 17 and other valves (such as the air intake valve 23 and the exhaust valve 24), the entire flow path of the OCEC analysis system is in a sealed state. After the flow path is pressurized, the pressure change in the flow path is observed through the reading of the pressure sensor in the flow path, thereby realizing the air tightness inspection of the entire flow path.

[0038] The method for using the OCEC analysis system of the present invention comprises the following steps: after the sample gas in the air flows into the furnace tube 11 through the sampling tube 5, the particulate matter in the sample gas is collected through the filter membrane 12. Then, the gas is switched to the helium bottle through the air inlet valve 23, and the helium in the helium bottle is input into the furnace tube 11 through the sampling tube 5, and the furnace tube 11 is purged to form an oxygen-free environment in the furnace tube 11, and the oxygen-free or low-oxygen gas is filled into the sealed space 20 through the air inlet pipe 21, and the air in the sealed space 20 is discharged through the air outlet pipe 22, and the filter membrane 12 is heated by the heating device 13, so that the organic carbon in the particulate matter on the filter membrane 12 is converted into gas. Since the oxygen-free environment is formed in the furnace tube 11, the elemental carbon in the particulate matter on the filter membrane 12 will not be converted into gas. Then, the gas is switched to the helium-oxygen bottle through the air inlet valve 23, and the mixed gas of helium and oxygen in the helium-oxygen bottle is input into the furnace tube 11 through the sampling tube 5 to form an oxygen environment, and then the heating device 13 is turned on to heat the filter membrane 12, so that the elemental carbon in the particulate matter on the filter membrane 12 is converted into gas. In the process of converting organic carbon and elemental carbon into gas, laser 4 continuously emits laser and irradiates the filter membrane 12, and the detection device receives the laser and detects the light intensity of the laser. In the process of converting organic carbon into gas, a part of organic carbon will be carbonized into cracked carbon, and the light intensity of the laser received by the detection device gradually weakens. In the process of converting cracked carbon / elemental carbon into gas, the light intensity of the laser received by the first detector 42 and the second detector 43 respectively increases gradually. When the light intensity of the laser received by the first detector 42 and the second detector 43 respectively recovers to the initial light intensity, it is used as the distinction point between organic carbon and elemental carbon, that is, before this, it is regarded as converted from organic carbon to gas, and after this, it is regarded as converted from elemental carbon to gas. Then, the gas is oxidized into carbon dioxide by the oxidation furnace 15, and the amount of carbon dioxide is detected by the carbon dioxide sensor 16. The amount of organic carbon and elemental carbon in the particulate matter on the filter membrane 12 is converted according to the amount of carbon dioxide, the sampling volume is converted according to the sampling flow rate, and the concentration of organic carbon and elemental carbon in the air particulate matter is converted according to the amount of organic carbon and elemental carbon in the particulate matter on the filter membrane 12 and the sampling volume. The last is the cooling stage, in which oxygen-free or low-oxygen gas is first filled into the sealed space 20 to cool it to an intermediate temperature, and then air is filled into the sealed space 20 to cool it to a specified temperature.

[0039] Embodiment 2

[0040] The difference between Example 2 and Example 1 mainly lies in the different settings and quantities of the laser, detector and spectrometer. The technical features that are the same as those in Example 1 will not be repeated here. The specific technical features shared with Example 1 and the distinguishing features of Example 2 relative to Example 1 are mainly described here.

[0041] like Figure 2As shown, an embodiment of the present invention provides an OCEC analysis system, including a sample furnace 1, the sample furnace 1 including a furnace tube 11, a filter membrane 12 arranged in the furnace tube 11, and a heating device 13 arranged outside the furnace tube 11 to heat the filter membrane 12. An insulation shell 2 is arranged outside the furnace tube 11 corresponding to the heating device 13, so as to seal and wrap the heating device 13 in the insulation shell 2, and a sealed space 20 is provided between the insulation shell 2 and the heating device 13. An air inlet pipe 21 and an air outlet pipe 22 are connected to the insulation shell 2 to fill the sealed space 20 with oxygen-free or low-oxygen gas, so that the heating device 13 is heated in the oxygen-free or low-oxygen space, thereby preventing the heating device 13 from being oxidized at high temperature, thereby improving the service life of the heating device 13.

[0042] The two ends of the furnace tube 11 extend out of the heat preservation shell 2 respectively. A first laser 401, a first beam splitter 402 and a first detector 403 are arranged at one end of the furnace tube 11, and a second laser 404, a second beam splitter 405 and a second detector 406 are arranged at the other end of the furnace tube 11. A part of the laser light emitted by the first laser 401 passes through the first beam splitter 402, the filter 12 and the second beam splitter 405 and enters the second detector 406, and another part of the laser light is reflected back by the filter 12 and then reflected by the first beam splitter 402 and then enters the first detector 403; similarly, a part of the laser light emitted by the second laser 404 passes through the filter 12 and then reflects by the first beam splitter 402 and then enters the first detector 403, and another part of the laser light is reflected back by the filter 12 and then reflected by the second beam splitter 405 and then enters the second detector 406.

[0043] The first laser 401 and the second laser 404 are both frequency modulated lights with different modulation frequencies. The first detector 403 and the second detector 406 demodulate the optical signals of the first laser 401 and the second laser 404 respectively according to the frequencies. The reflected light from the second laser 404 hitting the rear surface of the filter membrane 12 is used as a reference light to perform real-time correction on the transmitted light intensity and reflected light intensity of the first laser 401 passing through the filter membrane 12, thereby achieving accurate segmentation of the organic carbon and elemental carbon content of both the thermal light transmission method and the thermal light reflection method, thereby improving the detection accuracy.

[0044] At the same time, the light intensity of the second laser 404 entering the first detector 403 after passing through the filter membrane 12 is also the transmitted light intensity that effectively separates the organic carbon / elemental carbon, which plays a role in verifying the segmentation point of the transmitted light intensity and reflected light intensity of the first laser 401, further improving the accuracy of the organic carbon / elemental carbon content segmentation.

[0045] Embodiment 3

[0046] The difference between Example 3 and Example 1 mainly lies in the different settings of the laser, detector and spectrometer. The technical features that are the same as those in Example 1 will not be repeated here. The specific technical features shared with Example 1 and the distinguishing features of Example 3 relative to Example 1 are mainly described here.

[0047] like Figure 3 As shown, an embodiment of the present invention provides an OCEC analysis system, including a sample furnace 1, the sample furnace 1 including a furnace tube 11, a filter membrane 12 arranged in the furnace tube 11, and a heating device 13 arranged outside the furnace tube 11 to heat the filter membrane 12. An insulation shell 2 is arranged outside the furnace tube 11 corresponding to the heating device 13, so as to seal and wrap the heating device 13 in the insulation shell 2, and a sealed space 20 is provided between the insulation shell 2 and the heating device 13. An air inlet pipe 21 and an air outlet pipe 22 are connected to the insulation shell 2 to fill the sealed space 20 with oxygen-free or low-oxygen gas, so that the heating device 13 is heated in the oxygen-free or low-oxygen space, thereby preventing the heating device 13 from being oxidized at high temperature, thereby improving the service life of the heating device 13.

[0048] In this embodiment, both ends of the furnace tube 11 extend out of the insulation shell 2 respectively, a laser 4 is provided at one end of the furnace tube 11, a beam splitter 41 is provided between the laser 4 and the filter membrane 12, a first detector 42 is provided at the laser reflection end of the beam splitter 41, and a second detector 43 is provided at one end of the furnace tube 11 opposite to the laser 4. A sampling tube 5 is provided between the second detector 43 and the filter membrane 12 on the furnace tube 11, and an oxidation furnace 15 is provided between the filter membrane 12 and the laser 4 on the furnace tube 11. The laser 4 emits a laser, which is irradiated on the filter membrane 12 through the beam splitter 41. A part of the laser is received by the second detector 43 after passing through the filter membrane 1 and the light intensity of the laser is detected, and another part of the laser is received by the first detector 42 after being reflected by the filter membrane 12 and the beam splitter 41 and the light intensity of the laser is detected.

[0049] The laser 4 hits the filter membrane 12 through the beam splitter 41. A part of the laser passes through the filter membrane and enters the transmission light detector for detection. A part of the light is reflected from the surface of the filter membrane and hits the beam splitter. A part of the light that hits the beam splitter is reflected and enters the reflection light detector for detection. The beam splitter 41 is placed obliquely relative to the filter membrane 12. Optionally, the beam splitter 41 is placed at a 45° angle relative to the filter membrane 12. The sample containing atmospheric particulate matter enters from the input end and passes through the filter membrane 12. The filter membrane 12 intercepts the particles in the atmosphere. Most of the intercepted particles stay on the surface of the filter membrane, and a small part is in the shallow layer and the middle of the filter membrane. When the thickness of the filter membrane reaches a certain thickness, the filter membrane can completely intercept the particles at the front surface of the filter membrane, and they do not exist on the back of the filter membrane.

[0050] When laser is irradiated from the back of the filter membrane, the light passing through the filter membrane will be affected by the concentration of cracked carbon / elemental carbon on the filter membrane, as well as the intensity of the light source and the optical properties of the filter membrane, while the light reflected from the back of the filter membrane is only affected by the intensity of the light source and the optical properties of the filter membrane but not by the concentration of cracked carbon / elemental carbon on the filter membrane.

[0051] During the organic carbon / elemental carbon analysis process, the back reflected light is used to eliminate the fluctuation of the transmitted light intensity in real time, so that the transmitted light is only affected by the concentration of cracked carbon and elemental carbon, accurately dividing the organic carbon / elemental carbon content and improving the detection accuracy of organic carbon and elemental carbon.

[0052] This embodiment uses the back reflection method as a reference light to track and correct the change of the intensity of the transmitted light in real time, so as to achieve accurate segmentation of organic carbon / elemental carbon. The real-time correction method of this embodiment not only corrects the influence of the light source intensity fluctuation on the intensity of the transmitted light, but also corrects the influence of the change of the optical properties caused by the change of the filter membrane temperature on the intensity of the transmitted light, thereby improving the detection accuracy of the thermal light transmission method for measuring organic carbon and elemental carbon, and achieving accurate segmentation of organic carbon and elemental carbon.

[0053] Embodiment 4

[0054] The difference between Example 4 and Example 1 mainly lies in the different locations of the oxidation furnace. The technical features that are the same as those in Example 1 will not be described in detail here. The specific technical features shared with Example 1 and the distinguishing features of Example 4 relative to Example 1 are mainly described here.

[0055] like Figure 4 As shown, an embodiment of the present invention provides an OCEC analysis system, including a sample furnace 1, the sample furnace 1 including a furnace tube 11, a filter membrane 12 arranged in the furnace tube 11, and a heating device 13 arranged outside the furnace tube 11 to heat the filter membrane 12. An insulation shell 2 is arranged outside the furnace tube 11 corresponding to the heating device 13, so as to seal and wrap the heating device 13 in the insulation shell 2, and a sealed space 20 is provided between the insulation shell 2 and the heating device 13. An air inlet pipe 21 and an air outlet pipe 22 are connected to the insulation shell 2 to fill the sealed space 20 with oxygen-free or low-oxygen gas, so that the heating device 13 is heated in the oxygen-free or low-oxygen space, thereby preventing the heating device 13 from being oxidized at high temperature, thereby improving the service life of the heating device 13.

[0056] In the embodiment of the present invention, the heat preservation shell 2 includes a first shell section 201 and a second shell section 202, a sealed space 20 is formed between the first shell section 201 and the heating device 13, an oxidation furnace 15 is provided between the second shell section 202 and the furnace tube 11, and the second shell section 202 is closely attached to the furnace tube 11. The oxidation furnace 15 includes a manganese dioxide oxidant 151 closely attached to the outer wall of the furnace tube 11 and a heater 152 for heating the manganese dioxide oxidant 151. The input end of the oxidation furnace 15 is connected to the furnace tube 11 through a gas pipe 153, so that the gas after the organic carbon / element carbon in the particulate matter attached to the filter membrane 12 is pyrolyzed after step-by-step heating is input into the oxidation furnace 15. The output end of the oxidation furnace 15 is connected to a carbon dioxide sensor 16, and a control valve 17 is provided between the output end of the oxidation furnace 15 and the input end of the carbon dioxide sensor 16.

[0057] In the embodiment of the present invention, a laser 4 is provided at one end of the furnace tube 11, a beam splitter 41 is provided between the laser 4 and the filter membrane 12, a first detector 42 is provided at the laser reflection end of the beam splitter 41, and a second detector 43 is provided at one end of the furnace tube 11 opposite to the laser 4. A sampling tube 5 is provided between the second detector 43 and the filter membrane 12 on the furnace tube 11, and the oxidation furnace 15 is located between the filter membrane 12 and the laser 4. The laser 4 emits a laser, which is irradiated on the filter membrane 12 through the beam splitter 41. A portion of the laser light is received by the second detector 43 after passing through the filter membrane 1 and the intensity of the laser light is detected, and another portion of the laser light is received by the first detector 42 after being reflected by the filter membrane 12 and the beam splitter 41 and the intensity of the laser light is detected.

[0058] In the embodiment of the present invention, the laser 4, the beam splitter 41 and the first detector 42 are close to one end of the oxidation furnace 15, and the second detector 43 is close to one end of the sealed space 20. It can be understood that the laser 4, the beam splitter 41 and the first detector 42 can also be arranged at one end close to the sealed space 20, and the second detector 43 is arranged at one end close to the oxidation furnace 15.

[0059] The present invention makes the oxidation furnace 15 tightly fit on the furnace tube 11 in an annular shape. During analysis, the furnace tube 11 and the oxidation furnace 15 are both in a high temperature state, which reduces the loss of sample gas caused by the sample gas remaining on the inner wall of the furnace tube 11 after analysis, and at the same time, the structure is more compact and reliable.

[0060] In the present invention, since the oxidation furnace is annularly sleeved at the rear end of the main pipe, the entire area through which the analytical gas path passes is in a high temperature state, the temperature drop gradient is small, and the adsorption capacity of the inner wall to the analyzed sample is greatly weakened, which greatly reduces the loss of the sample. At the same time, this structure makes the entire furnace body more compact and reliable, and it is easier to miniaturize the equipment.

[0061] The reflected light detected by the first detector 42 is reflected by the rear surface of the filter membrane 12, while the particulate matter sample is mainly concentrated on the front surface of the filter membrane 12. When the thickness of the filter membrane 12 reaches a certain thickness, the light signal reflected by the rear surface of the filter membrane 12 is no longer affected by the particulate matter content, but only by the change in the light source intensity and the change in the optical properties of the filter membrane 12. The transmitted laser and the reflected laser are emitted by the same light source and irradiated onto the same filter membrane 12. The change in the reflected light will synchronously and real-time affect the change in the transmitted light signal. In addition to being affected by the change in the light source intensity and the change in the optical properties of the filter membrane, the change in the intensity of the transmitted light is only affected by the elemental carbon and cracked carbon content in the particulate matter on the filter membrane 12. The present invention uses reflected light to perform real-time correction on the transmitted light signal, which can more accurately segment the content of organic carbon and elemental carbon. Since each analysis process is corrected in real time, the influence of the drift of the intensity change of the transmitted light signal is greatly reduced.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An OCEC analysis system, comprising a sample furnace (1), the sample furnace (1) comprising a furnace tube (11), a filter membrane (12) arranged in the furnace tube (11), and a heating device (13) arranged outside the furnace tube (11) for heating the filter membrane (12), characterized in that: An insulation shell (2) is arranged outside the furnace tube (11) at a position corresponding to the heating device (13) so as to seal and wrap the heating device (13) in the insulation shell (2); a sealed space (20) is provided between the insulation shell (2) and the heating device (13); an air inlet pipe (21) and an air outlet pipe (22) are connected to the insulation shell (2) so as to fill the sealed space (20) with oxygen-free or low-oxygen gas so that the heating device (13) is heated in the oxygen-free or low-oxygen space; and both ends of the furnace tube (11) extend outside the insulation shell (2); A laser (4) is provided at one end of the furnace tube (11), a beam splitter (41) is provided between the laser (4) and the filter membrane (12), a first detector (42) is provided on the furnace tube (11) near the beam splitter (41) for receiving laser light reflected by the filter membrane (12) and the beam splitter (41) and detecting the laser light intensity, a second detector (43) is provided on the other end of the furnace tube (11) for receiving laser light passing through the filter membrane (12) and detecting the laser light intensity, a sampling tube (5) is connected between the second detector (43) and the filter membrane (12) on the furnace tube (11), and the laser light is irradiated from the back of the filter membrane; Alternatively, a first laser (401), a first beam splitter (402) and a first detector (403) are provided at one end of the furnace tube (11), and a second laser (404), a second beam splitter (405) and a second detector (406) are provided at the other end of the furnace tube (11); a portion of the laser light emitted by the first laser (401) passes through the first beam splitter (402), the filter membrane (12) and the second beam splitter (405) and then enters the second detector (406); another portion of the laser light is reflected back by the filter membrane (12) and then reflected by the first beam splitter (402) and then enters the first detector (406). A detector (403); a portion of the laser light emitted by the second laser (404) is reflected by the second beam splitter (405) and then passes through the filter (12) and is reflected by the first beam splitter (402) before entering the first detector (403); the other portion of the laser light is reflected back by the filter (12) and then reflected by the second beam splitter (405) before entering the second detector (406); the reflected light of the second laser (404) hitting the rear surface of the filter (12) is used as reference light to perform real-time correction on the intensity of the transmitted light and the reflected light of the first laser (401) passing through the filter (12).

2. The OCEC analysis system according to claim 1, characterized in that: An intake valve (23) is provided at the intake end of the intake pipe (21), and the input end of the intake valve (23) is connected to an oxygen-free or low-oxygen gas source, and the oxygen-free or low-oxygen gas enters the sealed space (20) through the intake pipe (21); an exhaust valve (24) is provided at the exhaust end of the outlet pipe (22), and the exhaust valve (24) has an exhaust port.

3. The OCEC analysis system according to claim 1, characterized in that: The heat-insulating shell (2) is made of a metal plate and a heat-insulating plate, and the heat-insulating plate is arranged closely to the inner wall of the metal plate.

4. The OCEC analysis system according to claim 2, characterized in that: A temperature measuring element (14) is provided on the furnace tube (11) near the filter membrane (12), and a suction pump (3) is provided at the output end of the exhaust valve (24).

5. The OCEC analysis system according to claim 1, characterized in that: The heating device (13) uses a heating wire wound around the outer periphery of the furnace tube (11) at a position corresponding to the filter membrane (12), and a high-temperature resistant insulating tube is arranged outside the heating wire.

6. A method for using the OCEC analysis system according to any one of claims 1 to 5, characterized in that: Before the heating device (13) starts heating, oxygen-free or low-oxygen gas is filled into the sealed space (20) through the air inlet pipe (21), and the air in the sealed space (20) is exhausted through the air outlet pipe (22).

7. A method for using the OCEC analysis system according to any one of claims 1 to 5, characterized in that: During cooling, oxygen-free or low-oxygen gas is firstly charged into the sealed space (20) to cool to an intermediate temperature, and then air is charged into the sealed space (20) to cool to a specified temperature.

8. A method for using the OCEC analysis system according to claim 4, characterized in that: When the temperature detected by the temperature measuring element (14) during the cooling process is greater than a set value, the air intake valve (23) is controlled to switch to an oxygen-free or low-oxygen source to fill in oxygen-free or low-oxygen gas, and the exhaust port of the exhaust valve (24) is controlled to be opened, so that the oxygen-free or low-oxygen gas enters the sealed space (20) through the air intake pipe (21), and the heat in the sealed space (20) is discharged from the exhaust port of the exhaust valve (24) through the air outlet pipe (22); when the temperature detected by the temperature measuring element (14) drops below the set value, the air intake valve (23) is controlled to switch to an air inlet, and the oxygen-free or low-oxygen source inlet is closed, and air is drawn into the sealed space (20) by the suction pump (3), so that the heat in the sealed space (20) is dissipated through the air outlet pipe (22).

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