Fixed bed reactor for realizing in-situ heat removal and in-situ temperature measurement of strong exothermic reaction based on thermoluminescence principle

Abstract

The utility model relates to a fixed bed reactor for realizing strong exothermic reaction in-situ heat removal and in-situ temperature measurement based on a thermoluminescence principle, which belongs to the field of fixed bed reaction devices, and can realize temperature and heat monitoring in an exothermic reaction process from multiple angles, strengthen heat transfer of a catalytic bed layer and effectively reduce or eliminate hot spots generated in the exothermic reaction process. The reactor comprises a fixed bed reaction tube, wherein a xenon lamp pretreatment system, an optical signal detection system and an infrared temperature measurement system are arranged at the top of the fixed bed reaction tube. The side end of the fixed bed reaction tube is a gas inlet; the fixed bed reaction tube is provided with a thermocouple inlet; the material of the reaction tube needs to meet optical signal detection and infrared temperature measurement at the same time, and optical signal and temperature detection is achieved under the condition that the catalytic reaction process is not affected; and a catalyst and a thermoluminescent material are filled in the reaction tube.

Description

Technical Field

[0001] The utility model belongs to a reactor suitable for realizing in-situ heat removal and in-situ temperature measurement of gas-phase exothermic reaction by thermoluminescence, and particularly relates to a fixed-bed reactor suitable for acetylene hydrogenation to ethylene reaction. Background Technique

[0002] Many chemical processes are highly exothermic reactions, such as acetylene hydrogenation reaction. For highly exothermic reactions, as the reaction proceeds, a large amount of heat will be released. If it is not removed in time, the temperature of the catalyst bed layer will increase, resulting in the formation of "hot spots". The large temperature difference not only increases a large amount of additional energy consumption, but also brings large temperature changes and heat shocks, thus easily causing catalyst failure, unstable reaction conversion rate and selectivity, and reduced system efficiency. More seriously, the high temperature and pressure changes during the reaction process are likely to cause problems such as system runaway temperature and pressure loss. At worst, it will damage the process equipment, and at worst, it will cause major safety accidents such as explosion, fire and casualties. Therefore, to ensure the normal progress of the catalytic reaction process and improve the reaction efficiency, it is necessary to remove the reaction heat in time.

[0003] For highly exothermic reactions, many types of reactors have been designed and many heat removal methods have been proposed. CN1736574A and CN207756118U propose a shell-and-tube fixed-bed reactor. By filling the catalyst in the clearance between the tubes to form a catalyst bed, the cooling medium flows outside the tubes for heat transfer. This can increase the heat transfer area of the fixed-bed reactor and shorten the heat transfer path, making the reaction temperature uniform in the axial and radial directions. However, this will bring difficulties in processing and greatly affect the effective filling amount of the catalyst. CN2415831 proposes to add superconducting fins on the reactor cylinder to conduct the heat released by the reaction out of the reactor. The heat removal capacity is more than 5 times that of the shell-and-tube reactor. However, the heat conducting fins only remove part of the surrounding heat and cannot solve the "hot spot" of the catalyst bed. Patent CN1260237A proposes to use heat-conducting metal particles as inert diluents in exothermic reactions to reduce and avoid the formation of hot spots in the fixed bed. This method only transfers the heat from the catalytic active sites to the diluents and does not make full use of the heat. Thermoluminescence means that when a crystal is heated, the electromagnetic radiation or other ionizing radiation originally absorbed and stored in the lattice defects will be released in the form of photons. Based on thermoluminescence to remove the heat of exothermic reactions, heat reuse can be achieved. At the same time, in recent decades, temperature measurement by luminescence has gradually become an important part of the temperature measurement field. This temperature measurement method has high spatial resolution and temperature measurement sensitivity compared with the traditional thermocouple temperature measurement method. The literature ACS Catal. 2018, 8, 2397-2401 proposes a strip temperature measurement method based on photoluminescence, but this luminescence process requires continuous excitation by an excitation source, which inevitably generates additional heat. Based on thermoluminescence to remove the heat of exothermic reactions and simultaneously achieve temperature measurement can avoid the problem of additional heat generation. Summary of the Invention

[0004] The purpose of the present utility model is to provide a fixed-bed temperature measurement reactor according to the concept of thermoluminescence. This reactor can strengthen the heat transfer of the catalytic bed, physically mix the thermoluminescent material with the catalyst, convert heat energy into light energy through thermoluminescence, and achieve the removal of the heat of exothermic reactions. On the other hand, the temperature is measured by in-situ monitoring of the change in the light intensity of the thermoluminescent material during the reaction process.

[0005] To achieve the above purpose, the present utility model provides the following technical solutions:

[0006] A fixed-bed reactor suitable for in-situ heat removal and in-situ temperature measurement of gas-phase exothermic reactions, as Figure 1As shown in the figure, it includes a heating jacket and a fixed-bed reaction tube; the fixed-bed reaction tube 2 is inserted through the heating jacket 4; a catalyst bed 3 is provided inside the fixed-bed reaction tube, including a catalyst for acetylene hydrogenation to ethylene and a thermoluminescent material; an air inlet 1 and an air outlet 6 are respectively provided at both ends of the fixed-bed reaction tube, with side-end air inlet and bottom-end air outlet; the top end material of the fixed-bed reaction tube 2 is a replaceable material. A thermocouple 5 is provided inside the fixed-bed reaction tube, with one end extending to the catalyst bed and the other end extending outside the fixed-bed reaction tube.

[0007] Keeping the temperature of the catalyst bed constant is a basic requirement to ensure the normal progress of the catalytic process. The lens of the infrared thermometer 13 is relatively large. If infrared temperature measurement is carried out on the side of the fixed bed, it will affect the heat preservation effect of the heating furnace, thus affecting the progress of the catalytic process. As mentioned above, in the present invention, temperature and optical signal are measured at the top end of the reaction tube of the fixed bed.

[0008] As Figure 1 shown in the figure, it is a xenon lamp pretreatment system. The xenon lamp pretreatment system includes a xenon lamp 7; when it is necessary to pretreat the thermoluminescent material, the catalyst bed inside the reaction tube is aligned through the xenon lamp probe to ensure uniform irradiation. According to the trap energy level depth formula where k is the Boltzmann constant, T n is the temperature value corresponding to the peak of the thermoluminescence curve, and δ is a parameter related to the temperature at half of the peak intensity; the defect depths of different materials are different, and the amount of electrons that can be stored is also different. Based on the principle of thermoluminescence, the luminescent material needs to store electrons and release electrons during heating for recombination with holes to emit light; the luminescent material is irradiated with ultraviolet light to ensure the storage of electrons. The amount of electrons stored by the luminescent material can be observed by the height of the thermoluminescence curve peak at different irradiation times. When the peak intensity is the highest, it represents that the amount of electrons stored is the largest at this time, and the time of ultraviolet treatment is the most appropriate at this time. After ultraviolet irradiation to store electrons, an inert gas or reaction gas atmosphere is then introduced to carry out a temperature-raising reaction on the catalyst bed.

[0009] As Figure 2As shown in the figure, it is an optical signal detection system. The optical signal measurement system includes a reflector 8, a condenser lens 9, a monochromator 10, a detector 11, and a darkroom 12. As mentioned above, the top of the fixed-bed reaction tube is made of a replaceable material. When replaced with quartz, the light intensity is measured. The optical signal collection system is at the top of the reaction tube 2, and the entire optical signal collection part is in the darkroom 12. The light emitted by the thermoluminescent material in the catalytic bed layer 3 after heating due to the release of electrons is refracted by 90° through the reflector 8 and converged by the condenser lens 9 and introduced into the monochromator 10. The light of the selected wavelength is passed through the detector 11 to measure the intensity of the optical signal. The detector converts the optical signal into an electrical signal to detect the intensity of the optical signal. Based on the exothermic reaction and the principle of thermoluminescence, the heat released by the exothermic reaction is removed by converting thermal energy into light energy. At the same time, by comparing the intensities of the optical signal detections in an inert atmosphere and a reaction gas atmosphere, temperature measurement can be achieved.

[0010] As Figure 3 As shown in the figure, it is an infrared temperature measurement system. The infrared temperature measurement system includes an infrared thermal imager 13. Infrared temperature measurement is to calculate the surface temperature of an object through the relationship between the radiation power and the temperature of the infrared radiation emitted by the object. To perform infrared temperature measurement in a reactor, it is necessary to ensure that infrared rays can pass through. As mentioned above, when the top of the fixed-bed reaction tube 2 is replaced with germanium glass, the germanium glass can ensure the passage of infrared rays, so that the temperature of the catalytic bed layer can be measured by infrared temperature measurement. When precise measurement of the catalytic bed layer temperature is required, the infrared thermal imager 13 can be used for temperature measurement.

[0011] The catalyst for acetylene hydrogenation to ethylene is a Pd-based, Ni-based, or Cu-based catalyst, and the thermoluminescent material is an inorganic oxide such as rare earth element-doped calcium fluoride, lithium fluoride, calcium sulfate, or lithium borate. The catalyst loading is 0.1 g to 0.5 g, and the thermoluminescent material loading is 0.1 g to 1 g. The catalyst and the thermoluminescent material are physically mixed, or rare earth elements are doped or atomically deposited on the catalyst to remove the heat of the exothermic reaction and measure the temperature.

[0012] The beneficial effects of the present utility model are as follows:

[0013] 1. Compared with the prior art, based on the principle of thermoluminescence, the present application proposes to mix the thermoluminescent material with the catalyst to remove the heat of the exothermic reaction and avoid the generation of hot spots in the catalytic bed layer while ensuring the normal progress of the catalytic reaction and without increasing the processing difficulty of the reactor.

[0014] 2. The present utility model combines infrared temperature measurement, optical signal detection with a fixed-bed reactor, designs the inner diameter, material, and inlet and outlet gas port modules of the fixed-bed reaction tube to meet the detection conditions, facilitates real-time monitoring of the reaction process, and performs temperature measurement from multiple angles, so as to obtain the true temperature of the catalytic reaction, further analyze the catalytic process, and improve the objectivity and effectiveness of catalyst performance evaluation.

[0015] To ensure that the material of the reaction tube can meet the requirements of both optical signal and temperature detection, the top of the fixed-bed reaction tube is a replaceable window. When replaced with a germanium glass window, infrared temperature measurement is carried out to ensure the normal progress of the infrared temperature measurement process; when replaced with a quartz window, light intensity detection is carried out. The light is introduced into the monochromator and photomultiplier tube through a reflector, and the light intensity is measured by converting the optical signal into an electrical signal. By comparing the light intensity during the reaction process with the light intensity at different temperatures in an inert atmosphere, the actual temperature during the reaction process can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the fixed-bed reactor and xenon lamp pretreatment system of the present utility model;

[0017] Figure 2 It is a schematic diagram of the fixed-bed reactor and optical signal measurement system of the present utility model;

[0018] Figure 3 It is a schematic diagram of the fixed-bed reactor and infrared temperature measurement system of the present utility model;

[0019] In the figure, 1. Inlet; 2. Fixed-bed reaction tube; 3. Catalyst bed; 4. Heating jacket; 5. Thermocouple; 6. Outlet; 7. Xenon lamp; 8. Reflector; 9. Condensing lens; 10. Monochromator; 11. Detector; 12. Darkroom; 13. Infrared thermal imager;

[0020] Figure 4 For the photocurrent test of different materials

[0021] Figure 5 For the photoluminescence spectra of different materials;

[0022] Figure 6 For the thermoluminescence spectrum of LiF.

[0023] Figure 7 For the thermoluminescence spectrum of CaF 2 . DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following further elaborates on the technical solutions of the present utility model in detail, but it is not a limitation of the present utility model.

[0025] A fixed-bed reactor suitable for realizing in-situ heat removal of strong exothermic reactions by thermoluminescence, comprising a fixed-bed reaction tube, and one of a xenon lamp pretreatment system, an optical signal detection system, and an infrared temperature measurement system is provided at the top of the fixed-bed reaction tube. The side end of the fixed-bed reaction tube is an air inlet, and the lower end is an air outlet; the fixed-bed reaction tube is provided with a thermocouple inlet; a catalyst bed 3 is arranged inside the reaction tube, and the catalyst bed 3 is filled with a catalyst; a heating jacket 4 is arranged outside the fixed-bed reaction tube 2, and a thermocouple is arranged below the fixed-bed reaction tube; the optical signal detection system sequentially includes a reflector 8, a condenser lens 9, a monochromator 10, and a detector 11; the reflector 8 and the condenser lens 9 are arranged in a darkroom 12.

[0026] Optical signal detection or temperature measurement is carried out at the top end of the fixed-bed reaction tube, and the side end is the air inlet, so as to ensure the temperature of the catalyst bed.

[0027] First, it is determined through photocurrent testing and photoluminescence spectroscopy that the thermoluminescent material has the ability to store electrons, such as Figure 4 , Figure 5 as shown.

[0028] Example 1: Pd / TiO 2 catalyst, thermoluminescent material CaF 2

[0029] First, 0.1 g of CaF 2 is added to the fixed-bed reactor; then, ultraviolet light with a wavelength of 365 nm is selected by a xenon lamp, and irradiation is carried out at a distance of 15 cm from the top of the reaction tube to CaF 2 under the condition of an irradiation intensity of 0.51 W / m 2 for 15 min; then, N 2 is introduced at a flow rate of 115 ml / min under one atmosphere, and the material is heated from room temperature to 250 °C at a heating rate of 5 °C / min, and a thermoluminescence spectrum test is carried out using the optical signal detection system to obtain the relationship between temperature and the ratio of thermoluminescence intensity. Then, 0.1 g of Pd / TiO 2 catalyst and 0.1 g of CaF 2 are physically mixed. Similarly, ultraviolet light with a wavelength of 365 nm is selected by a xenon lamp, and irradiation is carried out at a distance of 15 cm from the top of the reaction tube to CaF 2 for 15 min; then, 100 ml / min of 1% C 2 H 2 / C 2 H 4 , 15 ml / min of 10% H 2 / N 2Perform a hydrogenation reaction. Heat the material from room temperature to 150 °C at a heating rate of 5 °C / min. Use an optical signal detection system to detect the light intensity. Calculate the actual temperature of the catalytic reaction by substituting the thermoluminescence intensity ratio at this temperature into the standard thermoluminescence temperature measurement curve.

[0030] Example 2: PdCu MMO catalyst, thermoluminescent material Pr 3+ doped Y 3 Al 2 Ga 3 O 12

[0031] First, add 0.5 g of Pr 3+ doped Y 3 Al 2 Ga 3 O 12 , then select ultraviolet light with a wavelength of 365 nm using a xenon lamp, and irradiate for 15 min at a distance of 15 cm from the top of the reaction tube to Pr 2 under the condition of an irradiation intensity of 0.51 W / m 3+ doped Y 3 Al 2 Ga 3 O 12 ; then introduce N at a rate of 60 ml / min under a pressure of one atmosphere, heat the material from room temperature to 250 °C at a heating rate of 5 °C / min, and perform a thermoluminescence spectrum test using an optical signal detection system to obtain the relationship between temperature and thermoluminescence intensity ratio. Then physically mix 0.5 g of PdCu MMO catalyst with 0.5 g of Pr 2 , and again select ultraviolet light with a wavelength of 365 nm using a xenon lamp, and irradiate for 15 min at a distance of 15 cm from the top of the reaction tube to Pr 3+ doped Y 3 Al 2 Ga 3 O 12 ; then introduce 50 ml / min of 1% C 3+ doped Y 3 Al 2 Ga 3 O 12 at a distance of 15 cm from the top of the reaction tube under a pressure of one atmosphere; then introduce 10 ml / min of 10% H 2 H 2 / C 2 H 4 and 10 ml / min of 10% H 2 / N 2Perform a hydrogenation reaction. Heat the material from room temperature to 200 °C at a heating rate of 5 °C / min. Use an optical signal detection system to detect the light intensity. Calculate the actual temperature of the catalytic reaction by substituting the thermoluminescence intensity ratio at this temperature into the standard thermoluminescence temperature measurement curve.

Claims

1. A fixed bed reactor based on the principle of thermoluminescence to achieve in-situ heat removal and in-situ temperature measurement of a strong exothermic reaction, characterized in that: It comprises a heating jacket and a fixed bed reaction tube; a heating jacket is arranged outside the fixed bed reaction tube; a catalyst bed is arranged inside the fixed bed reaction tube; an air inlet and an air outlet are arranged at both ends of the fixed bed reaction tube; a thermocouple is arranged inside the fixed bed reaction tube, one end of the thermocouple extends to the catalyst bed, and the other end extends outside the fixed bed reaction tube; It also includes at least one of a xenon lamp pre-processing system, an optical signal detection system and an infrared temperature measurement system.

2. A fixed bed reactor for realizing in-situ heat removal and in-situ temperature measurement of a strong exothermic reaction based on the thermoluminescence principle according to claim 1, characterized in that: A xenon lamp pretreatment system, an optical signal detection system and an infrared temperature measurement system are arranged on the top of the reaction tube of the fixed bed.

3. A fixed bed reactor for realizing in-situ heat removal and in-situ temperature measurement of a strong exothermic reaction based on the thermoluminescence principle according to claim 1, characterized in that: The xenon lamp pretreatment system includes a xenon lamp.

4. A fixed bed reactor for realizing in-situ heat removal and in-situ temperature measurement of a strong exothermic reaction based on the principle of thermoluminescence according to claim 1, characterized in that: The optical signal measurement system includes a reflector, a condenser, a monochromator and a detector.

5. A fixed bed reactor for realizing in-situ heat removal and in-situ temperature measurement of a strong exothermic reaction based on the thermoluminescence principle according to claim 1, characterized in that: When the infrared temperature measurement system is used, the top of the fixed bed reaction tube is germanium glass.

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