CN117815901B - Filling type reactor for catalytic purification of carbon monoxide in fire smoke - Google Patents
Filling type reactor for catalytic purification of carbon monoxide in fire smoke Download PDFInfo
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- 238000011049 filling Methods 0.000 title claims abstract description 24
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 23
- 229910002091 carbon monoxide Inorganic materials 0.000 title claims abstract description 20
- 239000000779 smoke Substances 0.000 title claims abstract description 19
- 230000003197 catalytic effect Effects 0.000 title claims description 25
- 238000000746 purification Methods 0.000 title claims description 18
- 239000006260 foam Substances 0.000 claims abstract description 140
- 238000010438 heat treatment Methods 0.000 claims abstract description 97
- 239000002245 particle Substances 0.000 claims abstract description 72
- 238000006243 chemical reaction Methods 0.000 claims abstract description 44
- 238000000034 method Methods 0.000 claims abstract description 31
- 239000000969 carrier Substances 0.000 claims abstract description 28
- 238000013461 design Methods 0.000 claims abstract description 16
- 238000009826 distribution Methods 0.000 claims abstract description 16
- 238000006555 catalytic reaction Methods 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims description 37
- 238000012546 transfer Methods 0.000 claims description 11
- 239000003517 fume Substances 0.000 claims description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 claims description 6
- 230000035515 penetration Effects 0.000 claims description 6
- 239000004744 fabric Substances 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 5
- 238000005485 electric heating Methods 0.000 claims description 4
- 238000010992 reflux Methods 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 230000005672 electromagnetic field Effects 0.000 claims description 3
- 239000000835 fiber Substances 0.000 claims description 3
- 239000003921 oil Substances 0.000 claims description 3
- 239000010453 quartz Substances 0.000 claims description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 3
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 3
- 229910000859 α-Fe Inorganic materials 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 239000002918 waste heat Substances 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 description 10
- 125000006850 spacer group Chemical group 0.000 description 4
- 239000003546 flue gas Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229920002545 silicone oil Polymers 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- 238000004887 air purification Methods 0.000 description 1
- 230000003042 antagnostic effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- -1 copper cobalt titanium oxide Chemical compound 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000005338 heat storage Methods 0.000 description 1
- 238000007210 heterogeneous catalysis Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000002905 metal composite material Substances 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/88—Handling or mounting catalysts
- B01D53/885—Devices in general for catalytic purification of waste gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/007—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by irradiation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/864—Removing carbon monoxide or hydrocarbons
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/50—Carbon oxides
- B01D2257/502—Carbon monoxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2259/00—Type of treatment
- B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
- B01D2259/806—Microwaves
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
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Abstract
The invention discloses a filling type reactor for catalyzing and purifying carbon monoxide in fire smoke, which is characterized in that two foam carrier layers are arranged in a reaction channel, the wave-transmitting foam carrier layer at the outer layer is heated by adopting a wall surface heating mode, and the wave-absorbing foam carrier layer at the inner layer is heated by adopting a microwave heating mode, so that foam carriers (comprising wave-transmitting foam particle carriers and wave-absorbing foam particle carriers) arranged in the reaction channel can be heated in a layered manner, the temperature distribution of the foam carriers is more uniform, and the temperature distribution uniformity of the foam carriers can be ensured even under the condition that the diameter of the reaction channel is larger; namely, the layered filling type reactor can enlarge the pipe diameter of the reaction channel under the condition of meeting the uniformity of temperature distribution, thereby increasing the gas treatment capacity of the reactor, reducing the pressure drop of the reactor and improving the catalytic reaction performance of the reactor. The invention also discloses a design method and a use method of the layered filling type reactor.
Description
Technical Field
The invention belongs to the technical field of gas catalytic treatment, and particularly relates to a filling type reactor for catalytic purification of carbon monoxide in fire smoke.
Background
The harmful gas mortality ratio in building fires exceeds 60%, and in some ventilation limited buildings (such as tunnels, etc.), the smoke mortality ratio is more than 80%, and the smoke mortality is mostly due to CO. Aiming at harmful smoke generated in the fire process, ventilation is adopted to rapidly discharge the harmful smoke outdoors at present. Most of the existing smoke discharging designs are based on temperature, the influence factors of the CO generation amount in the fire process are more, the CO release amount of the real fire is difficult to predict, and the CO distribution and the temperature distribution are likely to show larger difference, and the low CO concentration of the personnel active area cannot be ensured only by smoke discharging. This means that in addition to the smoke evacuation means during a fire, it is necessary to reduce the smoke toxicity by smoke purification methods and to maintain a low CO concentration in the local environment for relatively closed and occupied spaces (e.g. tunnels, escape ways, refuge chambers, etc.).
The packed reactor is a reactor commonly used in heterogeneous catalysis due to the advantages of simple structure, small mechanical loss of the catalyst and the like. In order to stably exert the performance of the catalyst, a packed bed reactor is adopted to catalyze the carbon monoxide in the flue gas. To achieve good catalytic efficiency, the catalysts commonly available on the market all require a certain reaction temperature, which requires a heating treatment of the packed bed. In packed bed applications, heat transfer performance and reactor pressure drop are of major concern. The poor heat transfer performance easily causes uneven temperature distribution in the reactor, firstly causes that part of the catalyst cannot reach the optimal catalytic temperature, secondly causes that the catalyst is sintered and permanently deactivated due to overhigh temperature of the part of the catalyst, thirdly, the selective reaction can be used in some non-fire field scenes, such as chemical production, the reaction route is highly sensitive to the temperature, excessive byproducts can be generated due to uneven temperature, and the heat transfer performance of the reactor has important influence on the overall efficiency. And reactor pressure drop directly affects the energy consumption of use. The pressure drop and heat transfer are mostly antagonistic, and smaller particle diameter and pipe diameter are needed for better heat transfer performance, but large particle diameter and pipe diameter are needed for reducing the pressure drop.
The fixed packed bed reactor at the present stage improves the overall efficiency of the reactor mainly by optimizing energy supply, modifying particle forms, researching and developing catalytic materials and the like. Microwave heating is considered a potential way to achieve rapid bulk heating, selective heating and a more uniform temperature profile relative to wall heating for catalytic reactions requiring external energy supply. Different from the high center of the wall surface heating temperature curve, the microwave heating temperature curve is distributed with high axis and low wall surface, so that a local hot spot may be formed in a leeward surface air flow dead zone of partial particles in the bed layer, the penetration depth influence exists, and the thickness of a heating area is not excessively high. In the aspect of particle form transformation, foam type materials are increasingly used due to the improvement of production technology, the foam production of a structural bed is required to be customized on the use of a packed bed carrier, particles are more beneficial to the use of the packed bed, the pressure drop of a reactor can be greatly reduced due to the fact that the porosity of the foam packed bed is larger, and the reaction area can be increased at the same time, but research shows that the average flow velocity of air flow is lower, the gas-solid convection heat transfer coefficient is lower due to the larger porosity, and the temperature distribution of a catalytic bed using the foam carrier is more uneven.
In order to ensure that the temperature in the reactor is uniform, the ratio of the control pipe diameter of a large number of wall heating packed beds to the particle diameter of catalyst particles is within 15 at present, and in order to ensure the diffusion performance of gas phase reactants in the particles and ensure the reaction area, the particle diameter of the particles is often controlled to be in millimeter level, so that the pipe diameter is limited, the single pipe diameter of the existing packed reactor is mostly below 5cm, the flow rate in the pipe is too high under the condition of large flow, the pressure drop is too high, and meanwhile, in order to ensure the catalytic efficiency, the gas residence time is required to be ensured, and the filling length is easy to be too long. The large-scale industrial application often adopts a tubular type or multistage adiabatic type and the like, and the operation is complex, so that the method is not suitable for medium and small-sized places, such as flue gas catalytic purification of a small combustion furnace, catalytic purification of indoor pollutants, refuge room air purification, laboratory scale research and the like, and the prior art cannot meet the high-efficiency catalytic reaction of a medium and small-sized reactor.
Disclosure of Invention
In view of the above, the present invention aims to provide a packed reactor for catalytic purification of carbon monoxide in fire smoke, which can increase the pipe diameter, further increase the gas throughput and reduce the pressure drop under the condition of satisfying the uniformity of temperature distribution.
More uniform and meets the temperature conditions required for catalytic oxidation.
In order to achieve the above purpose, the present invention provides the following technical solutions:
the invention firstly provides a filling type reactor for catalyzing and purifying carbon monoxide in fire smoke, which comprises the following components:
a resonant cavity for reflecting microwaves to construct a microwave field;
A layered packed bed installed in the resonant cavity and located at the position of the strongest alternating electromagnetic field in the microwave field;
The resonant cavity is provided with a wave guide pipe which is connected with a microwave generator;
The layered packed bed comprises an outer cover, a reaction channel is arranged in the outer cover, and a wall heating sleeve is sleeved outside the reaction channel; one end of the outer cover is closed, a gap channel is arranged between the air outlet end of the reaction channel and the closed end of the outer cover, and a gas reflux channel communicated with the gap channel is formed by a gap between the outer cover and the wall heating sleeve; a wall heating cavity is formed between the wall heating sleeve and the reaction channel, and a heat medium is arranged in the wall heating cavity; the reaction channel is internally provided with two foam carrier layers, the two foam carrier layers are respectively a wave-transmitting foam carrier layer positioned at the outer layer and a wave-absorbing foam carrier layer positioned at the inner layer, the wave-transmitting foam carrier layer is filled with wave-transmitting foam particle carriers capable of penetrating microwaves, and the wave-absorbing foam carrier layer is filled with wave-absorbing foam particle carriers capable of absorbing microwave energy and converting the microwave energy into heat energy;
the layered packed bed further comprises wall heating means for heating the thermal medium.
Further, the wall heating device is arranged below the resonant cavity; the wall surface heating device adopts an electric heating device.
Further, the heat medium adopts heat conduction oil or silicone oil; the outer cover, the reaction channel and the wall heating sleeve are all made of quartz glass.
Further, the wave-transparent foam particle carrier is made of alumina ceramics; the wave-absorbing foam particle carrier is made of silicon carbide ceramic, ferrite or foam carbon.
Further, the porosities of the wave-transmitting foam particle carrier and the wave-absorbing foam particle carrier are 55% -65%; the particle sizes of the wave-transmitting foam particle carrier and the wave-absorbing foam particle carrier are 1 cm.
Further, a separation mesh cloth with flexibility is arranged between the wave-transmitting foam carrier layer and the wave-absorbing foam carrier layer, and the separation mesh cloth is made of heat-resistant plastic or quartz fiber.
Further, the microwave frequency generated by the microwave generator is 0.3-300GHz.
Further, the microwave generator generates microwaves having a frequency of 2.45GHz or 915MHz.
The invention also provides a design method of the filling type reactor, which comprises the steps of designing the diameter of the wave-absorbing foam carrier layer, designing the diameter of the wave-transmitting foam carrier layer and designing the wall heating cavity;
the design method of the diameter of the wave-absorbing foam carrier layer comprises the following steps:
D1＝min(Dp,Dh)
Dh＝λ0/3
Wherein: d 1 is the diameter of the wave-absorbing foam carrier layer; d h is the maximum heating length of the microwave; d p is the microwave penetration depth; lambda 0 is the microwave wavelength; epsilon' is the dielectric constant; epsilon' is the power loss factor; θ is the foam particle porosity;
the design method of the diameter of the wave-transparent foam carrier layer comprises the following steps:
the cylindrical contact surface between the planar simplified wall heating sleeve and the wave-transparent foam carrier layer is adopted, radial convection is ignored, only heat conduction is considered, and the method is achieved:
Wherein: lambda is the equivalent heat transfer coefficient; t is the temperature; l is the filling height in the wave-transparent foam carrier layer; q is the heat consumption per unit of fill volume;
The wall surface is an isothermal wall surface, the heat medium is consistent with the microwave heating set temperature, and when the boundary condition x=0 and x=d is that t=t 0, radial temperature distribution is obtained:
the radial temperature nadir is located at the x=d/2 position; d is the diameter of the wall heating sleeve;
the temperature difference between the temperature of the lowest point of the radial temperature and the wall surface temperature is not more than 10 percent, and then:
The heat consumption per unit volume comprises a reaction heat absorption q f and a heating air heat q air, and the gas temperature rises to the wall temperature linearly along the axial direction:
wherein: c is the specific heat of air, u is the air flow rate, ρ is the air density;
the design method of the wall heating cavity comprises the following steps: the ratio of the length to the thickness of the wall heating cavity is less than or equal to 3.
The invention also provides a using method of the filling type reactor, which comprises the following steps:
Step one: starting a wall heating device to preheat the heat medium and heat the wave-transparent foam particle carrier until the temperature of the heat medium reaches the catalytic reaction temperature;
step two: starting a microwave generator, and heating the wave-absorbing foam particle carriers after microwaves sequentially penetrate through the outer cover, the gas backflow channel, the wall heating sleeve, the wall heating cavity, the reaction channel and the wave-absorbing foam carrier layer until the temperatures of the wave-absorbing foam particle carriers in the wave-absorbing foam carrier layer and the wave-absorbing foam particle carriers in the wave-absorbing foam carrier layer reach the catalytic reaction temperature;
Step three: and introducing gas to be treated from the gas inlet end of the reaction channel, carrying out catalytic reaction on the gas in the process of passing through the wave-transparent foam carrier layer and the wave-absorbing foam carrier layer, flowing out the treated gas through the gap channel and the gas reflux channel, and preserving heat of the wall heating cavity by utilizing waste heat of the gas.
The invention has the beneficial effects that:
The invention relates to a filling type reactor for catalyzing and purifying carbon monoxide in fire smoke, which combines wall heating and microwave heating and has a layered filling structure, and specifically, two foam carrier layers are arranged in a reaction channel, an outer wave-transmitting foam carrier layer is heated in a wall heating mode, and an inner wave-absorbing foam carrier layer is heated in a microwave heating mode, so that foam carriers (comprising wave-transmitting foam particle carriers and wave-absorbing foam particle carriers) arranged in the reaction channel can be heated in a layered mode, the temperature distribution of the foam carriers is more uniform, and the temperature distribution uniformity of the foam carriers can be ensured even under the condition that the diameter of the reaction channel is larger; namely, the filling type reactor can enlarge the pipe diameter of the reaction channel under the condition of meeting the uniformity of temperature distribution, thereby increasing the gas treatment capacity of the reactor, reducing the pressure drop of the reactor and improving the catalytic reaction performance of the reactor.
Drawings
In order to make the objects, technical solutions and advantageous effects of the present invention more clear, the present invention provides the following drawings for description:
FIG. 1 is a schematic structural view of an embodiment of a packed reactor for catalytic purification of carbon monoxide from fire fumes according to the invention;
FIG. 2 is a schematic structural view of a layered packed bed;
FIG. 3 is a schematic view of a simplified cylindrical surface with a flat surface;
FIG. 4 is a graph of natural convection axial temperature distribution for a same power but different length to thickness ratios of a wall heating cavity.
Reference numerals illustrate:
10-a resonant cavity; 11-a waveguide;
20-layering packed beds; 21-an outer cover; 22-reaction channel; 23-wall heating sleeve; 23 a-wall heating chamber; 24-gap channel; 25-a gas return channel; 26-a wave-transparent foam carrier layer; 26 a-a wave-transparent foam particle carrier; 27-a wave-absorbing foam carrier layer; 27 a-a wave-absorbing foam particle carrier; 28-separating mesh cloth.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to limit the invention, so that those skilled in the art may better understand the invention and practice it.
As shown in fig. 1, the packed reactor for catalytic purification of carbon monoxide in fire smoke of this embodiment comprises a resonant cavity 10 and a layered packed bed 20. The resonant cavity 10 is used to reflect microwaves to construct a microwave field. Specifically, the resonator 10 is provided with a waveguide 11, and the waveguide 11 is connected to a microwave generator (not shown in the figure), and the resonator 10 has various structural forms, such as a cylinder shape, a square shape, and the like. A layered packed bed 20 is installed within the resonator 10 at the location of the strongest alternating electromagnetic field in the microwave field, i.e. near the maximum standing wave node.
Specifically, the layered packed bed 20 includes a housing 21, a reaction channel 22 is provided in the housing 21, and a wall heating sleeve 23 is provided outside the reaction channel 22. One end of the outer cover 21 is closed, a clearance channel 24 is arranged between the air outlet end of the reaction channel 22 and the closed end of the outer cover 21, and a gas return channel 25 communicated with the clearance channel 24 is formed in the clearance between the outer cover 21 and the wall surface heating sleeve 23. A wall heating chamber 23a is formed between the wall heating sleeve 23 and the reaction channel 22, and a heat medium is provided in the wall heating chamber 23 a. Two foam carrier layers are arranged in the reaction channel 22, wherein the two foam carrier layers are respectively a wave-transmitting foam carrier layer 26 positioned on the outer layer and a wave-absorbing foam carrier layer 27 positioned on the inner layer. The wave-transmitting foam carrier layer 26 is filled with wave-transmitting foam particle carriers 26a capable of transmitting microwaves, and the wave-absorbing foam carrier layer 27 is filled with wave-absorbing foam particle carriers 27a capable of absorbing microwave energy and converting the microwave energy into heat energy.
The layered packed bed 20 of the present embodiment further includes a wall heating device (not shown in the drawings) for heating the heat medium, and in particular, the wall heating device is disposed below the resonant cavity 10. The wall surface heating device of this embodiment adopts an electric heating device. The heat medium of this embodiment adopts heat conduction oil or silicone oil, has good wave permeability and fluidity, and realizes uniform heating of the whole wall surface by absorbing heat of the electric heating device 28 and performing natural convection. In order to facilitate natural convection and to ensure a certain heat storage capacity of the wall heating device, the thickness of the wall heating cavity 23a should not be too small.
That is, in the present embodiment, the wall heating chamber 23a, the heat medium, and the wall heating means constitute a wall heating means, and the wall heating means heats the outer side of the wave-transparent foam carrier layer 26. The microwaves sequentially pass through the outer cover 21, the gas return passage 25, the wall heating sleeve 23, the wall heating chamber 23a, the reaction passage 22, and the wave-transparent foam carrier layer 26, and then heat the wave-absorbing foam carrier layer 27 and the wave-absorbing foam particle carriers 27a.
In this embodiment, the outer cover 21, the reaction channel 22 and the wall heating sleeve 23 are made of quartz glass, so that not only good air tightness but also good wave transmission performance can be ensured.
In this embodiment, the wave-transparent foam particle carrier 26a is made of alumina ceramics, and has good wave-transparent performance and high thermal conductivity. The wave-absorbing foam particle carrier 27a is made of silicon carbide ceramic, ferrite or carbon foam, and has a high thermal conductivity. Specifically, the wave-transparent foam particle carrier 26a and the wave-absorbing foam particle carrier 27a have various structural forms, such as spherical, cylindrical, prismatic, and may be combined with perforations, etc., and the structural forms are selected in order to achieve the advantages of difficult processing and production and material saving. The interiors of the wave-transparent foam particle carriers 26a and the wave-absorbing foam particle carriers 27a should have high open cell contents, allowing gas to flow out from the pores inside the particles, preventing the particles from forming dead zones of gas flow in the lee side. Since too much porosity results in too low a surface area, too little porosity results in an increased pressure drop and the possibility of local air flow dead zones, in this embodiment, the porosity of both the wave-transparent foam particle carrier 26a and the wave-absorbing foam particle carrier 27a is 55% -65%. The wave-transparent foam particle carrier 26a and the wave-absorbing foam particle carrier 27a should be kept as high as possible in filling ratio, and in particular, should be kept small in porosity in the area close to the wall surface, and on the basis of this principle, the particle size should be as small as possible, and the particle sizes of the wave-transparent foam particle carrier 26a and the wave-absorbing foam particle carrier 27a are both 1 cm in this embodiment, which can be moderately enlarged in the order of magnitude equivalent to the existing particle filling.
In the preferred embodiment of this example, a spacer mesh 28 with flexibility is provided between the wave-transparent foam carrier layer 26 and the wave-absorbing foam carrier layer 27, the spacer mesh 28 is made of heat-resistant plastic or quartz fiber, so that the spacer mesh 28 has low microwave absorptivity and good insulation property, and meanwhile, the spacer mesh 28 has certain flexibility, and the side wall effect generated by the layered interface of the inner and outer layer particles is reduced by extrusion deformation in the filling process, so that the radial distribution of the porosity is free from abrupt change.
In this embodiment, the microwave generator generates microwaves having a frequency of 0.3 to 300GHz. The microwave frequency generated by the microwave generator of this embodiment is selected to be 2.45GHz or 915MHz. In this embodiment, the microwave generator employs a single-mode microwave reactor, the microwave generator generates 0.3-300GHz microwaves, preferably 2.45GHz microwaves or 915MHz microwaves, and the maximum 2.45GHz microwaves can be heated to a diameter thickness of about 4cm and the maximum 915MHz microwaves can be heated to a diameter thickness of about 11cm under the condition that the microwave penetration depth can be satisfied according to the bed diameter requirement.
The following describes in detail the embodiment of the method for designing a packed reactor for catalytic purification of carbon monoxide from fire smoke.
The design method of the filling type reactor comprises the steps of designing the diameter of a wave-absorbing foam carrier layer, designing the diameter of a wave-transmitting foam carrier layer and designing a wall heating cavity.
(1) The design method of the diameter of the wave-absorbing foam carrier layer comprises the following steps:
the filling diameter of the wave-absorbing foam carrier layer 27 should take a small value between the maximum heating length corresponding to single mode microwaves and the penetration depth of the microwaves into the particles. Specifically, the design method of the diameter of the wave-absorbing foam carrier layer comprises the following steps:
D1＝min(Dp,Dh)
Dh＝λ0/3
Wherein: d 1 is the diameter of the wave-absorbing foam carrier layer; d h is the maximum heating length of the microwave; d p is the microwave penetration depth; lambda 0 is the microwave wavelength; epsilon' is the dielectric constant; epsilon' is the power loss factor; θ is the foam particle porosity;
(2) The design method of the diameter of the wave-transparent foam carrier layer comprises the following steps:
The heat source of the wave-transparent foam carrier layer 26 can be regarded as heat conduction between the wall surface and the inner layer, and since the wall surface and the inner layer are cylindrical surfaces, the analytic solution guiding design cannot be obtained, so the embodiment adopts a cylindrical contact surface between the planar simplified wall surface heating sleeve 23 and the wave-transparent foam carrier layer 26, ignores radial convection and only considers heat conduction, ignores radial convection because the flow rate in the reactor is not constant, and only considers heat conduction, and as shown in fig. 3, obtains:
wherein: lambda is the equivalent heat transfer coefficient; t is the temperature; l is the filling height in the wave-transparent foam carrier layer; q is the heat consumed per unit of fill volume.
The wall surface is an isothermal wall surface, the heat medium is consistent with the microwave heating set temperature, and when the boundary condition x=0 and x=d is that t=t 0, radial temperature distribution is obtained:
the radial temperature nadir is located at the x=d/2 position; d is the diameter of the wall heating sleeve;
the temperature difference between the temperature of the lowest point of the radial temperature and the wall surface temperature is not more than 10 percent, namely:
(T0-T)/T0<10％
considering errors caused by plate heat transfer assumption, taking 1.2 times of safety coefficient, then:
The heat consumption per unit volume comprises a reaction heat absorption q f and a heating air heat q air, and the gas temperature rises to the wall temperature linearly along the axial direction:
wherein: c is the specific heat of air, u is the air flow rate, ρ is the air density;
(3) The design method of the wall heating cavity comprises the following steps: the ratio of the length to the thickness of the wall heating chamber is 3 or less, as shown in fig. 4.
According to the design method of the filling type reactor in the embodiment, the diameter of the reaction channel 22 can easily reach more than 15cm, and the maximum diameter can be close to 30cm, and compared with the prior filling type reactor, the pipe diameter is mostly less than 5cm, and the treated air quantity is improved by more than 8 times under the same airspeed. According to the performance of the existing catalyst, the non-noble metal composite catalyst formed by copper cobalt titanium oxide can realize the catalytic efficiency of more than 90% of 1000ppm of carbon monoxide at the catalyst bed temperature of 110 ℃ at the volume space velocity of 20000h -1, so that the packed reactor with the reaction channel 22 having the diameter of 30cm and the length of 40cm can effectively purify 566m 3 flue gas per hour.
The embodiment also provides a using method of the filling type reactor, which comprises the following steps:
Step one: starting a wall heating device to preheat the heat medium and heat the wave-transparent foam particle carrier 26a until the temperature of the heat medium reaches the catalytic reaction temperature;
Step two: after starting the microwave generator, microwaves sequentially penetrate through the outer cover 21, the gas backflow channel 25, the wall heating sleeve 23, the wall heating cavity 23a, the reaction channel 22 and the wave-transmitting foam carrier layer 26, and then heat the wave-absorbing foam particle carriers 27a until the temperatures of the wave-transmitting foam particle carriers 27a in the wave-transmitting foam carrier layer 27 and the wave-absorbing foam particle carriers 26a in the wave-absorbing foam carrier layer 26 reach the catalytic reaction temperature;
Step three: the gas to be treated is introduced from the gas inlet end of the reaction channel 22, the gas undergoes catalytic reaction in the process of passing through the wave-transparent foam carrier layer 26 and the wave-absorbing foam carrier layer 27, the treated gas flows out through the gap channel 24 and the gas return channel 25, and the heat of the gas is utilized to preserve the heat of the wall heating cavity 23a, so that ineffective heat dissipation of a heat medium is reduced. The microwave and wall energy inputs are adjusted in real time according to the sensor temperature, keeping the temperatures of the wave-transparent foam carrier layer 26, the wave-absorbing foam carrier layer 27 and the wall heating cavity 23a all reach the set values.
The above-described embodiments are merely preferred embodiments for fully explaining the present invention, and the scope of the present invention is not limited thereto. Equivalent substitutions and modifications will occur to those skilled in the art based on the present invention, and are intended to be within the scope of the present invention. The protection scope of the invention is subject to the claims.
Claims (10)
1. A filling type reactor for the catalytic purification of carbon monoxide in fire smoke is characterized in that: comprising the following steps:
a resonant cavity for reflecting microwaves to construct a microwave field;
A layered packed bed installed in the resonant cavity and located at the position of the strongest alternating electromagnetic field in the microwave field;
The resonant cavity is provided with a wave guide pipe which is connected with a microwave generator;
The layered packed bed comprises an outer cover, a reaction channel is arranged in the outer cover, and a wall heating sleeve is sleeved outside the reaction channel; one end of the outer cover is closed, a gap channel is arranged between the air outlet end of the reaction channel and the closed end of the outer cover, and a gas reflux channel communicated with the gap channel is formed by a gap between the outer cover and the wall heating sleeve; a wall heating cavity is formed between the wall heating sleeve and the reaction channel, and a heat medium is arranged in the wall heating cavity; the reaction channel is internally provided with two foam carrier layers, the two foam carrier layers are respectively a wave-transmitting foam carrier layer positioned at the outer layer and a wave-absorbing foam carrier layer positioned at the inner layer, the wave-transmitting foam carrier layer is filled with wave-transmitting foam particle carriers capable of penetrating microwaves, and the wave-absorbing foam carrier layer is filled with wave-absorbing foam particle carriers capable of absorbing microwave energy and converting the microwave energy into heat energy;
the layered packed bed further comprises wall heating means for heating the thermal medium; the wall heating device is arranged below the resonant cavity.
2. The packed reactor for the catalytic purification of carbon monoxide from fire fumes according to claim 1, wherein: the wall surface heating device adopts an electric heating device.
3. The packed reactor for the catalytic purification of carbon monoxide from fire fumes according to claim 1, wherein: the heat medium adopts heat conduction oil; the outer cover, the reaction channel and the wall heating sleeve are all made of quartz glass.
4. The packed reactor for the catalytic purification of carbon monoxide from fire fumes according to claim 1, wherein: the wave-transparent foam particle carrier is made of alumina ceramics; the wave-absorbing foam particle carrier is made of silicon carbide ceramic, ferrite or foam carbon.
5. The packed reactor for the catalytic purification of carbon monoxide from fire fumes according to claim 1, wherein: the porosities of the wave-transmitting foam particle carrier and the wave-absorbing foam particle carrier are 55% -65%; the particle sizes of the wave-transmitting foam particle carrier and the wave-absorbing foam particle carrier are 1 cm.
6. The packed reactor for the catalytic purification of carbon monoxide from fire fumes according to claim 1, wherein: a flexible separation mesh cloth is arranged between the wave-transmitting foam carrier layer and the wave-absorbing foam carrier layer, and the separation mesh cloth is made of heat-resistant plastic or quartz fiber.
7. The packed reactor for the catalytic purification of carbon monoxide from fire fumes according to claim 1, wherein: the microwave frequency generated by the microwave generator is 0.3-300GHz.
8. The packed reactor for catalytic purification of carbon monoxide from fire fumes according to claim 7, wherein: the microwave frequency generated by the microwave generator is 2.45GHz or 915MHz.
9. A method of designing a packed reactor according to any one of claims 1 to 8, characterized in that: the method comprises the steps of designing the diameter of a wave-absorbing foam carrier layer, designing the diameter of a wave-transmitting foam carrier layer and designing a wall heating cavity;
the design method of the diameter of the wave-absorbing foam carrier layer comprises the following steps:
D1＝min(Dp,Dh)
Dh＝λ0/3
Wherein: d 1 is the diameter of the wave-absorbing foam carrier layer; d h is the maximum heating length of the microwave; d p is the microwave penetration depth; lambda 0 is the microwave wavelength; epsilon' is the dielectric constant; epsilon' is the power loss factor; θ is the foam particle porosity;
the design method of the diameter of the wave-transparent foam carrier layer comprises the following steps:
the cylindrical contact surface between the planar simplified wall heating sleeve and the wave-transparent foam carrier layer is adopted, radial convection is ignored, only heat conduction is considered, and the method is achieved:
Wherein: lambda is the equivalent heat transfer coefficient; t is the temperature; l is the filling height in the wave-transparent foam carrier layer; q is the heat consumption per unit of fill volume;
The wall surface is an isothermal wall surface, the heat medium is consistent with the microwave heating set temperature, and when the boundary condition x=0 and x=d is that t=t 0, radial temperature distribution is obtained:
the radial temperature nadir is located at the x=d/2 position; d is the diameter of the wall heating sleeve;
the temperature difference between the temperature of the lowest point of the radial temperature and the wall surface temperature is not more than 10 percent, and then:
considering errors caused by flat heat transfer, taking 1.2 times of safety coefficient, then:
The heat consumption per unit volume comprises a reaction heat absorption q f and a heating air heat q air, and the gas temperature rises to the wall temperature linearly along the axial direction:
wherein: c is the specific heat of air, u is the air flow rate, ρ is the air density;
the design method of the wall heating cavity comprises the following steps: the ratio of the length to the thickness of the wall heating cavity is less than or equal to 3.
10. A method of using the packed reactor according to any one of claims 1 to 8, wherein: the method comprises the following steps:
Step one: starting a wall heating device to preheat the heat medium and heat the wave-transparent foam particle carrier until the temperature of the heat medium reaches the catalytic reaction temperature;
step two: starting a microwave generator, and heating the wave-absorbing foam particle carriers after microwaves sequentially penetrate through the outer cover, the gas backflow channel, the wall heating sleeve, the wall heating cavity, the reaction channel and the wave-absorbing foam carrier layer until the temperatures of the wave-absorbing foam particle carriers in the wave-absorbing foam carrier layer and the wave-absorbing foam particle carriers in the wave-absorbing foam carrier layer reach the catalytic reaction temperature;
Step three: and introducing gas to be treated from the gas inlet end of the reaction channel, carrying out catalytic reaction on the gas in the process of passing through the wave-transparent foam carrier layer and the wave-absorbing foam carrier layer, flowing out the treated gas through the gap channel and the gas reflux channel, and preserving heat of the wall heating cavity by utilizing waste heat of the gas.
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| CN1266739A (en) * | 1999-03-10 | 2000-09-20 | 中国科学院金属研究所 | Microwave chemical reactor |
| CN211448802U (en) * | 2019-12-23 | 2020-09-08 | 武汉理工大学 | Automobile exhaust multi-effect purification device based on microwave heat and non-heat effect catalysis |
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| CN104437075B (en) * | 2014-10-13 | 2018-02-16 | 河北科技大学 | Utilize the method for microwave heatable catalytic pyrolysis processing VOC |
| JP6021881B2 (en) * | 2014-11-13 | 2016-11-09 | マイクロ波化学株式会社 | Chemical reaction apparatus and chemical reaction method |
| CN110155941B (en) * | 2019-05-24 | 2020-11-20 | 山东大学 | Microwave heating hydrogen production device based on thermochemical cycle, hydrogen production method and application |
| CN113209921A (en) * | 2020-01-21 | 2021-08-06 | 中国石油化工股份有限公司 | Microwave coupling catalytic reactor and VOCs treatment facility |
| CN113209918A (en) * | 2020-01-21 | 2021-08-06 | 中国石油化工股份有限公司 | Microwave coupling catalytic reactor and VOCs treatment facility |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1266739A (en) * | 1999-03-10 | 2000-09-20 | 中国科学院金属研究所 | Microwave chemical reactor |
| CN211448802U (en) * | 2019-12-23 | 2020-09-08 | 武汉理工大学 | Automobile exhaust multi-effect purification device based on microwave heat and non-heat effect catalysis |
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