CN113813886B

CN113813886B - Super-infrared air-flotation shallow-layer fluidized reactor

Info

Publication number: CN113813886B
Application number: CN202111244256.3A
Authority: CN
Inventors: 李钒; 王坦伦; 侯海元
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2022-08-02
Anticipated expiration: 2041-10-26
Also published as: CN113813886A

Abstract

The invention discloses a super-infrared air-flotation shallow fluidized reactor, which is a novel fluidized reactor for ZIF pyrolysis. The device comprises a main air inlet pipe, a porcelain boat lower air inlet pipe, a tube furnace, a collecting target, a porcelain boat upper cover, a gas exchange hole, a porcelain boat main body, a wire mesh, a magnetic ball, a porcelain boat lower air inlet, an air outlet pipe, an ultra-infrared control device and an ultra-infrared pulse transmitting device; the invention designs a method for solving the problem of nonuniform heating of a ferromagnetic ZIF material due to agglomeration in the pyrolysis process by applying a shallow fluidization technology and an ultra-infrared magnetic levitation technology on the basis of a traditional tubular furnace reactor, improves a porcelain boat, introduces a gas exchange hole to solve the problem that powder is easily blown away by protective gas, and simultaneously adds a collecting target to collect zinc volatilized in the ZIF-8 pyrolysis process. The device simple structure can solve multiple problem among the pyrolysis process.

Description

Super-infrared air-flotation shallow-layer fluidized reactor

Technical Field

The invention relates to the field of fluidized reactors, in particular to a super-infrared air-flotation shallow fluidized reactor.

Background

The metal M-N-C material formed by pyrolysis of the zeolite imidazolyl framework ZIF is widely concerned in the field of heterogeneous catalysis due to the special appearance, simple preparation process, relatively low price and capability of efficiently catalyzing various chemical reactions. ZIF-8 formed by coordination of zinc ions and 2-methylimidazole can be used for preparing various M-N-C catalysts because other metal ions are moved to an N-C site due to volatilization of Zn in the pyrolysis process, so that the ZIF-8 has wider application.

In the field of electrocatalysis, M-N-C catalysts of different atomic sites can catalyze a variety of reactions, such as: oxygen reduction reaction ORR, oxygen evolution reaction OER, hydrogen evolution reaction HER, and carbon dioxide reduction reaction CO ₂ RR, etc., and compared to a conventional electrocatalyst, the ZIF material has an advantage in that pyrolysis generates conductive carbon, and thus an additional conductive agent is not required. In the face of the current energy crisis and environmental pollution problems, there is a great need to develop such catalysts that are inexpensive and sustainable. Therefore, its application to electrocatalytic reactions is a hot tide of current research.

With research, the following problems have been found to exist in the pyrolysis of ZIF materials: firstly, the ZIF powder containing metal is agglomerated due to nonuniform local heating in the pyrolysis process, the metal is more likely to agglomerate due to nonuniform local heating on the outer surface, and organic matters are incompletely carbonized due to insufficient internal heating, so that the conductivity of the material is influenced, and the activity and the stability of the catalyst are reduced due to nonuniform internal and external heating; secondly, in order to ensure that the internal air of the traditional porcelain boat is replaced by protective gas as much as possible, the upper cover of the porcelain boat is generally not completely sealed, so that powder is easily blown away in the process of introducing the protective gas to influence the yield; finally, zinc vapor volatilizes to the cold end of the furnace tube to condense in the high-temperature pyrolysis process of the ZIF-8, so that an airflow channel is easily blocked, the stability of airflow of the protective gas is influenced, and potential safety hazards are easily caused. Therefore, it is necessary to design and develop a new ZIF material thermal treatment reactor.

Disclosure of Invention

The invention aims to solve the problems that the catalytic performance of a ferromagnetic ZIF material is affected due to nonuniform heating caused by powder agglomeration during heat treatment, the product powder is easily blown away by protective gas due to the fact that an upper cover of a porcelain boat is not sealed, and the gas path is blocked due to condensation of zinc volatilized at high temperature of ZIF-8 at a cold end, so that the novel ultra-infrared air-flotation shallow-layer fluidized reactor is provided. The powder is suspended to form a shallow fluidized state by introducing protective gas from the bottom to the top in the vertical direction of the porcelain boat, so that the problem of local uneven heating is solved and the surface of the powder is continuously updated. In the middle and later period of reaction, iron is replaced on the powder to make the material have ferromagnetism, and the super-infrared has magnetic effect on the ferromagnetic material to make the powder suspended to form a shallow fluidized bed which is easy to control. The powder can be prevented from agglomerating in the pyrolysis process through the two modes, so that the powder is heated uniformly, and the iron particles subjected to super-infrared magnetic suspension do not need gas, so that the use of protective gas can be reduced. The gas exchange holes are added in the lateral direction of the porcelain boat, so that the upper cover of the porcelain boat can be ensured to be completely closed, and meanwhile, the protective gas can replace the air in the porcelain boat, so that the powder is not easy to blow away. The collecting targets are arranged at the two ends of the inlet and the outlet of the tubular furnace, so that the zinc vapor can be condensed on the surface of the collecting targets without blocking a gas path.

In order to achieve the purpose, the invention provides a super-infrared air-flotation shallow fluidized reactor, which structurally comprises: the device comprises a main air inlet pipe 1, a porcelain boat lower air inlet pipe 2, a tube furnace 3, a collecting target 4, a porcelain boat upper cover 5, a gas exchange hole 6, a porcelain boat main body 7, a silk screen 8, a magnetic ball 9, a porcelain boat lower air inlet 10, an air outlet pipe 11, a super-infrared control device 12 and a super-infrared pulse transmitting device 13.

The assembly is shown in fig. 1, and the main inlet pipe 1 and the outlet pipe 11 are connected to flanges at two sides of the tube furnace 3 according to the installation specification of the tube furnace. The air inlet pipe 2 under the porcelain boat is arranged below the flange side of the main air inlet pipe 1, and the other end of the air inlet pipe 2 under the porcelain boat is connected with the air inlet 10 under the porcelain boat. Two collecting targets 4 are symmetrically placed in the furnace tube with the same distance from the two sides of the tube furnace tube opening, and the position is ensured to be at the cold end of the tube furnace. Then, the porcelain boat 5-10 is placed in an isothermal zone at the center of the tube furnace to ensure the uniform heat treatment temperature. And the ultra-infrared control device 12 is connected with the ultra-infrared pulse emitting device 13 to ensure that the intensity of the ultra-infrared pulse is controllable. The ultra-infrared pulse emitting device 13 is vertically placed at the lower side of the porcelain boat 5-10 outside the tube furnace, and the infrared emitting light source is aligned to the porcelain boat 5-10 in the tube furnace to be started in the reaction.

In the specific structure of the porcelain boat 5-10, the porcelain boat upper cover 5 is completely attached to the upper side of the porcelain boat main body 7, so that the tightness of the porcelain boat in the heat treatment process is ensured. The gas exchange holes 6 are perpendicular to the horizontal gas flow during the heat treatment and are located at a position higher than the highest possible level of the fluidised powder. The upper part of the porcelain boat main body 7 is of a cuboid structure, the size of the upper part of the porcelain boat main body is basically the same as that of a traditional porcelain boat, the lower part of the porcelain boat main body is of an inverted regular-prism frustum structure, the size of the upper surface of the porcelain boat main body needs to be consistent with that of a rectangular lower surface of the upper part of the porcelain boat main body 7, and the length of the rectangular side of the lower surface of the prism frustum is larger than the diameter of the lower air inlet 10 of the porcelain boat. The silk screen 8 is clamped at the junction of the upper part and the lower part of the porcelain boat main body 7, the size of the silk screen is consistent with the rectangle of the upper surface of the frustum of prism, and the mesh number of the silk screen is smaller than that of the powder. The magnetic balls 9 are sized to completely fill the lower portion of the porcelain boat body 7 and are sufficiently large so as not to be displaced by the air flow in the vertical direction. The lower air inlet 10 of the porcelain boat is circular, the circle center of the lower air inlet coincides with the center of gravity of the rectangle on the lower surface of the main body 7 of the porcelain boat, and the diameter of the lower air inlet is the same as the tail end of the lower air inlet pipe 2 of the porcelain boat, so that the lower air inlet and the lower air inlet pipe can be matched.

The invention has the advantages that: first, a shallow fluidized bed with gas blown is applied to constantly renew the powder surface. Secondly, as the reaction proceeds, the powder has ferromagnetism, the surface of the powder is updated more fully by applying infrared pulses, the churning is more violent, and the effect of the shallow fluidized bed is more obvious. Thus, insufficient reaction due to agglomeration of the powder during pyrolysis can be prevented. Thirdly, in the later stage of the heat treatment, the fluidization of the powder is completely controlled by far infrared pulses, so that the use of protective gas can be reduced. And finally, by applying the collecting target, byproduct zinc powder generated by ZIF-8 pyrolysis can be collected, and an outlet pipeline is prevented from being blocked, so that the effect of killing two birds with one stone is achieved.

The main air inlet pipe is connected with a flange at the inlet of the tube furnace, and the air tightness is ensured to be good.

The main air inlet pipe is made of rubber, plastics and other materials with certain flexibility.

The tube furnace is made of materials such as quartz, ceramics, corundum and the like which can be used by common tube furnaces.

The collecting target is a flat cylindrical sheet with the inner diameter equal to or slightly smaller than that of the furnace tube, and a plurality of centrosymmetric hole structures taking the circle center as the center are arranged on the sheet.

The positions of the two collecting targets are the cold ends in the tube furnace and respectively extend into the inlet and the outlet of the tube furnace at the same distance.

The collecting target is made of high-temperature resistant solid materials such as corundum, quartz, ceramics, cement and the like.

The porcelain boat comprises a porcelain boat upper cover, a gas exchange hole, a porcelain boat main body, a silk screen, a magnetic ball and a porcelain boat lower air inlet structure.

The porcelain boat is arranged in the middle isothermal zone of the tube furnace tube of the tube furnace.

The lower air inlet pipe of the porcelain boat is led in from the flange at the inlet of the tube furnace, and the sealing performance of the flange cannot be damaged.

The tail end of the lower air inlet pipe of the porcelain boat is consistent with the caliber of the lower air inlet of the porcelain boat and is connected with the tail end of the lower air inlet pipe of the porcelain boat, and the lower air inlet pipe of the porcelain boat is required to bear the weight of the porcelain boat.

The lower air inlet pipe of the porcelain boat is made of hard, heat-resistant and bearable materials such as ceramics, corundum and quartz.

The porcelain boat main body and the porcelain boat upper cover are made of high-temperature resistant solid materials such as quartz, corundum and ceramics.

The gas exchange holes are vertical to the horizontal airflow direction and are uniformly arranged on two sides of the porcelain boat.

The silk screen is made of metal materials such as iron, steel and copper with good ductility and high melting point.

The magnetic balls are required to be uniformly filled in the cone part of the porcelain boat in size, and are made of high-melting-point and high-density materials such as steel, iron, copper, quartz, ceramics, corundum and the like.

Drawings

FIG. 1 is a perspective view of a fluidized reactor at an early stage of reaction, in which: 1. the device comprises a main air inlet pipe 2, a porcelain boat lower air inlet pipe 3, a tube furnace 4, collecting targets 5-10, a porcelain boat 11, an air outlet pipe 12, an ultra-infrared control device 13 and an ultra-infrared pulse transmitting device.

FIG. 2 is a perspective view showing a middle stage of the reaction in the fluidized reactor, and the respective structures are the same as those in FIG. 1.

FIG. 3 is a perspective view of the fluidized reactor in the latter stage of the reaction, and the respective structures are the same as those in FIG. 1.

FIG. 4 is an enlarged perspective view of the porcelain boat, in which: 5. the porcelain boat comprises a porcelain boat upper cover 6, a gas exchange hole 7, a porcelain boat main body 8, a wire mesh 9, magnetic balls 10 and a porcelain boat lower air inlet.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.

The present invention is described in further detail below with reference to the attached drawings.

The specific operations in the heat treatment are shown in fig. 1, 2, and 3.

At the beginning of the heat treatment, as shown in FIG. 1. Opening the main gas inlet pipe 1 and the porcelain boat lower gas inlet pipe 2, and adjusting the flow of protective gas to ensure that the gas can just blow the powder to a proper height to form a fluidized bed, wherein the gravity G borne by the particles and the buoyancy F of the gas _{Floating body} Equal in size and opposite in direction. The heating device of the tube furnace 3 is turned on to start heating. The super-infrared control device 12 and the super-infrared pulse transmitting device 13 are turned off at this time.

As shown in FIG. 2, the heat treatment reaches a certain levelAfter the degree is over, the powder has ferromagnetism, the super infrared control device 12 and the super infrared pulse emission device 13 are started, the super infrared control device 12 is adjusted to change the infrared intensity of the super infrared pulse emission device 13, so that the fluidization degree of the magnetic powder is more intense, the flow of gas in the lower gas inlet pipe 2 of the porcelain boat is adjusted as necessary, and the downward gravity G and the upward buoyancy F borne by the unreacted ferromagnetic particles are ensured _{Floating body} And an upward magnetic force F _{Magnetic field} The three can be balanced.

As shown in figure 3, at the later stage of the heat treatment, the ferromagnetic powder completely reacts, at this time, the gas in the lower gas inlet pipe 2 of the porcelain boat is turned off, the ultra-infrared control device 12 is adjusted to change the infrared intensity of the ultra-infrared pulse emission device 13, so that the fluidization of the completely reacted ferromagnetic powder is only influenced by the magnetic force, and at this time, the downward gravity G and the upward magnetic force F of the completely reacted ferromagnetic particles are ensured _{Magnetic field} Are equal in size.

And when the temperature of the heat treatment is reduced to the room temperature, closing the ultra-infrared control device to ensure that the ultra-infrared pulse emitting device does not emit infrared rays any more, and taking out the pyrolyzed product for later use according to the correct operation specification of the tube furnace.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and embellishments can be made without departing from the principle of the present invention, and these should also be construed as the protection scope of the present invention.

Claims

1. The utility model provides a super infrared air supporting shallow layer fluidized reactor which characterized in that: the main air inlet pipe (1) and the air outlet pipe (11) are connected to flanges on two sides of the tube furnace (3) according to the installation specification of the tube furnace; the porcelain boat lower air inlet pipe (2) is arranged below the flange side of the main air inlet pipe (1), and the other end of the porcelain boat lower air inlet pipe (2) is connected with a porcelain boat lower air inlet (10); the two collecting targets (4) are symmetrically placed in the furnace tube with the same distance from two sides of the opening of the tubular furnace tube and are positioned at the cold end of the tubular furnace tube; the porcelain boat (5-10) is placed in an isothermal zone at the center of the tube furnace to ensure the uniform heat treatment temperature; the ultra-infrared control device (12) is connected with the ultra-infrared pulse emitting device (13) to ensure that the intensity of the ultra-infrared pulse is controllable; the ultra-infrared pulse emitting device (13) is vertically arranged at the lower side of the porcelain boat (5-10) outside the tube furnace, and the infrared emitting light source is aligned to the porcelain boat (5-10) in the tube furnace; the gas exchange holes (6) are vertical to the horizontal gas flow in the heat treatment process and are positioned higher than the highest position which can be reached by the fluidized powder; the gas exchange holes are vertical to the direction of the horizontal gas flow and are uniformly formed on two sides of the porcelain boat; the magnetic balls (9) are of a size which completely fills the lower part of the whole porcelain boat main body (7), and the quantity is enough to ensure that the magnetic balls cannot be displaced under the air flow blowing in the vertical direction.

2. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the porcelain boat upper cover (5) is completely attached to the upper side of the porcelain boat main body (7) to ensure the tightness of the porcelain boat upper cover in the heat treatment process; the upper part of the porcelain boat main body (7) is of a cuboid structure, the lower part of the porcelain boat main body is of an inverted regular-prism-shaped structure, the size of the upper surface of the porcelain boat main body needs to be consistent with the size of a rectangular lower surface of the upper part of the porcelain boat main body (7), and the length of the rectangular side of the lower surface of the prism is larger than the diameter of the lower air inlet (10) of the porcelain boat; the silk screen (8) is clamped at the junction of the upper part and the lower part of the porcelain boat main body (7), the size of the silk screen is consistent with that of the rectangle on the upper surface of the frustum pyramid, and the mesh number of the silk screen is smaller than that of the powder; the lower air inlet (10) of the porcelain boat is circular, the circle center of the lower air inlet coincides with the rectangular gravity center of the lower surface of the porcelain boat main body (7), and the diameter of the lower air inlet is the same as the tail end of the lower air inlet pipe (2) of the porcelain boat, so that the lower air inlet and the lower air inlet are matched.

3. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the main air inlet pipe is connected with a flange at the inlet of the tube furnace and is made of rubber or plastic.

4. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the collecting target is a flat cylindrical sheet with the inner diameter equal to or smaller than that of the furnace tube, and a plurality of centrosymmetric hole structures taking the circle center as the center are arranged on the sheet; the positions of the two collecting targets are the cold ends in the tube furnace and respectively extend into the inlet and the outlet of the tube furnace for the same distance.

5. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the collecting target is made of corundum, quartz, ceramic and cement high-temperature resistant solid materials;

6. The ultra-infrared air-float shallow fluidized reactor as claimed in claim 1, wherein: the porcelain boat is arranged in the middle isothermal zone of the tube furnace tube of the tube furnace.

7. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the inlet tube is followed under the porcelain boat flange introduction of tube furnace entrance, and the air inlet aperture is unanimous under the tail end of the inlet tube and the porcelain boat, interconnect under the porcelain boat, and needs the intake tube bears the weight of porcelain boat under the porcelain boat.

8. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the material of the lower air inlet pipe of the porcelain boat is ceramic, corundum and quartz.

9. The ultra-infrared air-flotation shallow-layer fluidized reactor as claimed in claim 1, characterized in that: the material of the silk screen is metal material with ductility of iron, steel and copper and high melting point;

the magnetic balls are uniformly filled in the cone of the porcelain boat, and the material is steel, iron, copper, quartz, ceramic or corundum with high melting point and high density.