A heating transmission device suitable for in-situ detection of ultrahigh temperature pyrolysis reaction

Abstract

The application discloses a heating transmission device suitable for in-situ detection of ultrahigh-temperature pyrolysis reaction, comprising a heating pipe and an adjusting assembly; a sample outlet end of the heating pipe is connectable to a detection device; the heating pipe is divided into a low-temperature zone, a high-temperature zone and an annealing zone; a first water-cooled electrode is arranged outside the low-temperature zone; and a second water-cooled electrode is arranged outside the annealing zone; the adjusting assembly comprises a guide rail and a sliding block; and the sliding block is connected with the first water-cooled electrode or not. The application forms a variable-diameter and variable-temperature zone through combination design of the heating pipe and the water-cooled electrode, guarantees contact between the heating pipe and the protective electrode, builds a relatively slow and uniform temperature gradient in the annealing zone, guarantees generation and dispersion of product molecules and improves transmission efficiency of macromolecular compounds. The application is convenient to connect with a mass spectrometer, can realize in-situ analysis of ultrahigh-temperature pyrolysis reaction and solves the problem that macromolecular products such as polycyclic aromatic hydrocarbons, fullerenes and the like cannot be detected in-situ due to aggregation caused by intermolecular forces in the pyrolysis reaction.

Description

TECHNICAL FIELD

[0001] The present application relates to a heating and conveying device for in-situ detection of ultra-high temperature pyrolysis reaction. BACKGROUND

[0002] Pyrolysis refers to a process of chemical reaction of organic matter under oxygen-deficient or oxygen-free conditions by using high temperature. Research on the mechanism of pyrolysis reaction is of great significance in improving energy efficiency, reducing environmental pollution, developing new materials, improving process and industrial application, etc. Pyrolysis reaction is a complex heterogeneous and non-homogeneous reaction system, and research on its mechanism can promote the development of physical chemistry, thermodynamics and kinetics, and greatly promote basic scientific research. Through mechanism research, an accurate reaction model can also be constructed, which can provide scientific basis for industrial production process and guide production.

[0003] The key to determining the mechanism of pyrolysis reaction lies in the capture and characterization of active intermediates in the reaction process. The introduction of a capture agent in the reaction system can stabilize the metastable active substances, but the introduction of substances unrelated to the reaction may change the progress of the reaction and affect the pyrolysis reaction. The advantage of in-situ detection is that it can directly analyze in the original position or environment of the reaction, directly detect the intermediate products in the reaction without processing or transferring the reaction products, and is closer to the true state of the reaction. Some pyrolysis reactions require high-temperature annealing conditions to generate target products, and general tube furnaces cannot withstand excessively high temperatures (greater than 1200℃). Moreover, if the temperature gradient is not controlled during annealing, the reaction products will be rapidly aggregated together due to intermolecular forces, which is quite unfavorable for in-situ detection, and may result in the failure to detect the originally generated products, and the solid particles generated by aggregation may affect the subsequent reaction. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provides a heating and conveying device for in-situ detection of ultra-high temperature pyrolysis reaction.

[0005] The technical scheme adopted by the present application to solve its technical problems is: a heating transmission device suitable for in-situ detection of super-high-temperature pyrolysis reaction is provided, comprising a heating pipe and an adjusting assembly; the heating pipe comprises a sample inlet end and a sample outlet end, the sample outlet end is used for connecting a detection device; the heating pipe is sequentially divided into a low-temperature zone, a high-temperature zone and an annealing zone according to the distance from the sample inlet end; the low-temperature zone is provided with a first water-cooled electrode, and the annealing zone is provided with a second water-cooled electrode; the adjusting assembly comprises a guide rail and a sliding block, and the sliding block is arranged on the guide rail and connected with the first water-cooled electrode.

[0006] In the present application, the outer diameters of the low-temperature zone and the annealing zone increase towards the high-temperature zone, and the lengths of the zones are sequentially high-temperature zone, annealing zone and low-temperature zone from short to long; the contact area of the first water-cooled electrode with the low-temperature zone is greater than the contact area of the second water-cooled electrode with the annealing zone.

[0007] In the present application, the first water-cooled electrode and the second water-cooled electrode are slotted on the side close to the high-temperature zone, and a protective electrode is arranged in the slot.

[0008] In the present application, the materials of the heating pipe and the protective electrode include graphite, which has a high melting point, meets the needs of super-high temperature, has good electrical conductivity and facilitates current heating; the materials of the first water-cooled electrode and the second water-cooled electrode include copper.

[0009] In the present application, the sample inlet end of the heating pipe is connected with a sample inlet pipeline through a clamping sleeve adapter.

[0010] In the present application, the sample outlet end is provided with a small hole, the detection device comprises a mass spectrometer, and the sample outlet end is connected with the mass spectrometer through a sampling cone.

[0011] In the present application, the first water-cooled electrode and the second water-cooled electrode are connected with a heating power supply, and the first water-cooled electrode and the second water-cooled electrode are provided with a circulating water channel inside.

[0012] In the present application, the adjusting assembly comprises a guide rail, a fixed block and a sliding block, the guide rail and the heating pipe are arranged in parallel, and the sliding block and the fixed block are arranged on the guide rail and respectively connected with the first water-cooled electrode and the second water-cooled electrode in an insulated manner.

[0013] In the present application, the adjusting assembly further comprises a bottom plate, the guide rail is fixed on the bottom plate, the guide rail is a screw rod, the sliding block is sleeved on the screw rod through a bearing, and the end of the screw rod is provided with a hand wheel.

[0014] In the present application, the heating pipe is arranged in a vacuum reaction chamber.

[0015] Compared with the background art, the technical scheme has the following advantages:

[0016] 1. The application adopts the design of variable diameter of graphite heating tube, the temperature range of high temperature zone is wide, the highest can reach 3000 DEG C, which can meet the extreme high temperature pyrolysis reaction; and the temperature gradient of annealing area can be effectively controlled, the product formation is ensured while avoiding molecular aggregation, the transmission efficiency of product is greatly improved, and at the same time, macromolecular compounds can enter mass spectrometry and be detected;

[0017] 2. The asymmetric and adjustable water-cooled copper electrode is used as the cooling design, the diameter and length of the graphite heating tube are designed, that is, the copper electrode is protected by water cooling due to the high reaction temperature of the super-high temperature pyrolysis, and the temperature gradient of the heating tube area can be controlled for different reaction systems;

[0018] 3. The application utilizes the heat conduction of the high temperature zone center to the two end regions through the graphite heating tube itself, on the other hand, the cylindrical graphite electrode (which can be punched in the middle to make the graphite tube pass through) is arranged near the high temperature zone of the water-cooled motor, the high temperature zone is separated from the copper electrode by using the graphite electrode, which avoids the direct contact between the copper electrode and the high temperature zone, which may melt the copper electrode, and secondly, if the high temperature zone contacts the cooler water-cooled copper electrode outlet, the temperature will drop sharply, which will increase the possibility of molecular aggregation, therefore, after isolation, the risk of temperature gradient change of the high temperature region and the two end regions is reduced;

[0019] 4. The sample inlet end of the low temperature zone is connected with the external pipeline through the adapter of the graphite tube rotating sleeve, which has strong sealing property, can increase the beam intensity, and is beneficial to sampling detection.

[0020] 5. The application is convenient to connect with a sampling cone and mass spectrometry, the small hole at the end of the tube can improve the pressure resistance, and in-situ detection of pyrolysis reaction under high pressure can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a structure schematic view of the embodiment device.

[0022] Figure 2 It is a structure schematic view of the embodiment graphite tube.

[0023] Figure 3 It is a practical use schematic view of the embodiment.

[0024] Figure 4 Fig. (a) and (b) are in-situ detection results of the embodiment device connected with mass spectrometer.

[0025] Wherein, 1 is a graphite heating tube; 2 is a protection electrode (right); 3 is a protection electrode (left); 4 is a second copper electrode (right); 5 is a first water-cooled copper electrode (left); 6 is a sleeve adapter; 7 is an insulating block; 8 is a fixed block; 9 is a sliding block; 10 is a bearing; 11 is a bottom plate; 12 is a hand wheel; and 13 is a screw rod. DETAILED DESCRIPTION

[0026] The application solutions are described below in combination with the drawings and embodiments. The terms "horizontal", "left", "right" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the application. In addition, the terms "first" and "second" are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0027] Embodiment

[0028] The embodiment is a heating and conveying device suitable for in-situ detection of ultrahigh temperature pyrolysis reaction, which comprises a graphite heating tube 1 and an adjusting assembly. As shown in Figure 1 , the graphite heating tube 1 is laid horizontally and comprises a sample inlet end at the left end and a sample outlet end 1 at the right end, the sample outlet end 1 is provided with a small hole for connecting a detection device; the graphite heating tube 1 is divided into a low-temperature zone, a high-temperature zone and an annealing zone in order of the distance from the sample inlet end (i.e. from left to right), the low-temperature zone is provided with a first water-cooled electrode 5, and the annealing zone is provided with a second water-cooled electrode 4.

[0029] As shown in Figure 2 , the graphite heating tube 1 has the largest diameter in the high-temperature zone, the diameters of the low-temperature zone and the annealing zone increase towards the high-temperature zone, the tube length 114 mm, the outer diameter 8 mm, the inner diameter 6 mm, and the outer diameter of the central high-temperature zone is 10 mm. The tube lengths of the zones from short to long are high-temperature zone 10 mm, annealing zone 41 mm and low-temperature zone 63 mm. A 1 mm small hole is provided at the end of the annealing zone.

[0030] The first water-cooled electrode 5 and the second water-cooled electrode 4 are connected with a heating power supply, and a circulating water channel is arranged inside the first water-cooled electrode 5 and the second water-cooled electrode 4. The first water-cooled electrode 5 and the second water-cooled electrode 4 adopt an asymmetric design, and the material is copper. The contact area of the first water-cooled electrode 5 with the low-temperature area is greater than the contact area of the second water-cooled electrode 4 with the annealing area. Because the cooling effect is related to the contact area, in order to maintain the temperature of the annealing area, a smaller water-cooled copper electrode is used for water cooling, so that the cooling gradient is relatively gentle. The left low-temperature area is the end through which the reactant is introduced, and high temperature is not required, so a larger water-cooled copper electrode is used to make the temperature as low as possible. The first water-cooled electrode 5 and the second water-cooled electrode 4 are slotted on the side close to the high-temperature area, and the protection electrodes 2 and 3 are arranged in the slots. The protection electrodes 2 and 3 in the embodiment are graphite electrodes, which are cylindrical bodies with a length of 18 mm and a hole in the middle through which the graphite heating pipe 1 passes. The graphite electrodes are used to separate the high-temperature area from the water-cooled copper electrode, which can avoid the direct contact between the water-cooled copper electrode and the high-temperature area, and can prevent the copper from melting. If the high-temperature area contacts the relatively cold water-cooled copper electrode, the outlet temperature will drop sharply, which will increase the possibility of molecular aggregation. Therefore, after isolation, the risk is reduced.

[0031] When installed, the graphite heating pipe 1 penetrates the left and right water-cooled copper electrodes and the left and right graphite electrodes, and is fixed by being clamped by the left and right graphite electrodes in the middle variable-diameter area. The sample inlet end of the graphite heating pipe 1 is connected with a sample inlet pipeline through a clamping sleeve adapter 6, which facilitates sampling and sealing. The main heating area of the graphite heating pipe 1 is the high-temperature area, i.e. the middle variable-diameter area, which is the area where pyrolysis reaction occurs. The heat can be conducted to both ends through the graphite material, so that a temperature gradient that slowly decreases to both sides is formed. Through testing, when the temperature of the high-temperature area is 928℃, the temperature of the annealing area decreases with the increase of the distance from the high-temperature area, and the temperature at the end is 450℃. The whole temperature field has a relatively gentle and uniform drop gradient. At this time, the temperature can disperse the pyrolysis products such as polycyclic aromatic hydrocarbons and fullerenes in the form of gas phase, which is beneficial to the in-situ sampling and mass spectrometry detection later. The graphite heating pipe 1 is arranged in a vacuum reaction chamber, and the detection device includes a mass spectrometer. The sample outlet end 1 is connected with the mass spectrometer through a sampling cone, and the sample outlet end 1 is provided with a 1mm round hole. After the pyrolysis products pass through the small hole, they expand sharply to form a molecular beam into the sampling cone for in-situ detection by the mass spectrometer.

[0032] The adjusting assembly includes a guide rail, a fixed block 8 and a sliding block 9, and further includes a bottom plate. The guide rail and the graphite heating pipe 1 are arranged in parallel. The sliding block 9 and the fixed block 8 are arranged on the guide rail and are respectively insulatedly connected with the insulating blocks 7 at the bottom of the first water-cooled electrode 5 and the second water-cooled electrode 4. The adjusting assembly further includes a bottom plate 11. The guide rail is fixed on the bottom plate 11. The guide rail is a screw rod 13. The sliding block is sleeved on the screw rod 13 through a bearing 10. The end of the screw rod 13 is provided with a hand wheel 12. The movement of the water-cooled electrode can be realized by rotating the hand wheel 12.

[0033] The method used in this embodiment is as follows:

[0034] 1. Fix the whole device in the vacuum reaction cavity through the bottom plate.

[0035] 2. Connect the power supply wiring to the first water-cooled copper electrode and the second water-cooled copper electrode.

[0036] 3. Open the mechanical pump to vacuumize, introduce carrier gas into the cavity, and provide appropriate reaction pressure.

[0037] 4. Open the gas valve, and use the mass flow meter to control the raw material vapor flow rate into the graphite heating tube 1.

[0038] 5. Turn on the heating power supply, and adjust the output current according to the required temperature.

[0039] 6. Measure the temperature and collect data, and turn off the power supply and the gas valve after the reaction is completed.

[0040] Since the reactants are introduced into the graphite heating tube 1 under appropriate pressure, and an electric current is applied to the copper electrodes at both ends of the graphite heating tube 1, the graphite heating tube 1 generates high temperature. By adjusting the distance between the water-cooled copper electrodes and the length of each region of the graphite heating tube 1, a slow and uniform temperature gradient can be constructed using the principle of heat conduction from the center of the graphite heating tube 1 to both sides. The reactants undergo pyrolysis in the high-temperature zone, and generate pyrolysis products such as polycyclic aromatic hydrocarbons and fullerenes through the annealing zone. The annealing zone is maintained at a relatively high temperature, which avoids the spontaneous aggregation of large molecular weight compounds due to strong intermolecular forces, thereby affecting subsequent reactions and detection. Subsequently, the dispersed product molecules are rapidly expanded through the small hole under high pressure and sprayed into the last high vacuum zone to form a molecular beam for mass spectrometric detection.

[0041] The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A heating transfer device suitable for in-situ detection of ultra-high temperature pyrolysis reactions, characterized in that: The device includes a heating tube and an adjustment assembly. The heating tube includes an inlet end and an outlet end, the outlet end being used to connect to a detection device. The heating tube is divided into a low-temperature zone, a high-temperature zone, and an annealing zone according to their distance from the inlet end. A first water-cooled electrode is fitted over the low-temperature zone, and a second water-cooled electrode is fitted over the annealing zone. The adjustment assembly includes a guide rail and a sliding block, the sliding block being disposed on the guide rail and connected to the first water-cooled electrode. The outer diameter of the low-temperature zone and the annealing zone increases towards the high-temperature zone, and the tube lengths of the zones, from shortest to longest, are the high-temperature zone, the annealing zone, and the low-temperature zone; the contact area between the first water-cooled electrode and the low-temperature zone is greater than the contact area between the second water-cooled electrode and the annealing zone.

2. The heating and transmission device for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 1, characterized in that: The first and second water-cooled electrodes have grooves on the side near the high-temperature zone, and protective electrodes are installed in the grooves.

3. The heating and transmission device for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 2, characterized in that: The heating element and the protective electrode are made of graphite, and the first and second water-cooled electrodes are made of copper.

4. The heating and transfer device for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 1, characterized in that: The sample inlet of the heating tube is connected to the sample inlet line via a compression fitting adapter.

5. A heating transfer device suitable for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 1, characterized in that: The sample outlet has a small hole, and the detection device includes a mass spectrometer. The sample outlet is connected to the mass spectrometer via a sampling cone.

6. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 1, characterized in that: The first and second water-cooled electrodes are connected to a heating power source, and circulating water channels are provided inside the first and second water-cooled electrodes.

7. A heating transmission device suitable for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 1, characterized in that: The adjustment assembly includes a guide rail, a fixed block, and a sliding block. The guide rail and the heating tube are arranged in parallel. The sliding block and the fixed block are disposed on the guide rail and are respectively insulated from and connected to the first water-cooled electrode and the second water-cooled electrode.

8. A heating transfer device suitable for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 7, characterized in that: The adjustment assembly also includes a base plate, the guide rail is fixed on the base plate, the guide rail is a screw, the sliding block is sleeved on the screw through a bearing, and a handwheel is provided at the end of the screw.

9. A heating transfer device suitable for in-situ detection of ultra-high temperature pyrolysis reactions according to claim 1, characterized in that: The heating element is located in the vacuum reaction chamber.

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