CN111298728B - Gas distributor and application thereof in HCl (hydrochloric acid) oxidation fluidized bed - Google Patents
Gas distributor and application thereof in HCl (hydrochloric acid) oxidation fluidized bed Download PDFInfo
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- CN111298728B CN111298728B CN202010233613.5A CN202010233613A CN111298728B CN 111298728 B CN111298728 B CN 111298728B CN 202010233613 A CN202010233613 A CN 202010233613A CN 111298728 B CN111298728 B CN 111298728B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
- B01J8/34—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique with stationary packing material in the fluidised bed, e.g. bricks, wire rings, baffles
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/03—Preparation from chlorides
- C01B7/04—Preparation of chlorine from hydrogen chloride
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Abstract
The invention provides a gas distributor and application thereof in an HCl oxidation fluidized bed. The gas distributor comprises a gas distribution plate, and the gas distribution plate is divided into a circular central area and a circular side wall area; air inlets are uniformly formed in the air distribution plate, and a porous blast cap is sealed and fixed above each air inlet through a metal cover plate; the porous blast cap is a SIC porous sintering blast cap. The included angle between the inclined plane of the porous blast cap in the central area and the horizontal direction is smaller than that of the side wall area, and the wall thickness of the porous blast cap in the central area is larger than that of the side wall area. The invention can solve the technical problems of uneven gas distribution, poor fluidization quality, erosion corrosion of reactor internals and catalyst abrasion and pulverization of the fluidized bed.
Description
Technical Field
The invention relates to a distributor, in particular to a gas distributor and application thereof in an HCl oxidation fluidized bed.
Background
In chemical, metallurgical, pharmaceutical and other industries, there are many production processes using chlorine as a raw material, and a large amount of HCl is produced. The fluidized bed catalytic oxidation technology is regarded as the most potential green chemical process for realizing the cyclic utilization of byproduct HCl resources. The existing fluidized bed reactor mostly adopts a perforated plate type or metal perforated hood type gas distributor, and due to the characteristics of high temperature and high corrosion of a system and the design defects of the distributor, the following technical problems exist in the using process:
1. the over-high local gas velocity of the fluidized bed causes serious abrasion of catalyst particles, and a great amount of catalyst fine powder harmful to the fluidized state is generated while the catalyst loss is serious;
2. the local high gas velocity gas flow carries solid particles to cause scouring abrasion of the reactor wall and the inner components;
3. the fluidized bed has uneven fluidization and dead zones, so that the heat and mass transfer efficiency is reduced;
4. local overheating of fluidization causes hardening of catalyst particles and loss of active components;
5. the system has strong corrosivity, the metal components protruding from the distributor are easy to abrade and corrode, the overhaul workload is large, the device stability is poor, and the operation period is short.
In order to avoid the problems, the long-period stable operation of the device is realized, and effective measures are needed to ensure that the airflow in the HCl oxidation fluidized bed is uniformly distributed, the gas and the solid are fully and uniformly contacted, and the scouring abrasion caused by high-speed airflow is avoided. The gas distributor is the most key part for realizing uniform distribution of gas flow in the dense-phase zone of the fluidized bed and uniform fluidization of gas and solid.
Various gas distributor designs have been proposed by designers for the problems of maldistribution of gas flow in a fluidized bed and dead zones in fluidization. CN105423742A discloses a distribution plate with a suspension guide vane, which has the function of flow equalization; CN105597655A discloses using multiple layers of distribution plates to adjust the gas pressure distribution to make the gas velocity uniform. Although the technical scheme optimizes the airflow distribution of the fluidized bed to a certain degree, the problem of high local airflow speed still exists, and especially the problem of scouring abrasion cannot be effectively solved in the area near the vent hole.
In order to solve the problems, CN105289424A discloses a regulating means between a hood and a distribution plate to control the air quantity to achieve the effect of uniform fluidization; CN1207088C discloses a distributor with square jet holes or strip jet slit hood and anti-leakage weir, wherein a layer of air film is formed on the upper surface of the distribution plate of the fluidized bed to lift the whole bed of material, thereby fully fluidizing; CN106994321A discloses a fluidized bed gas distribution plate with a first substrate for maintaining particle suspension, secondary hood holes and hoods for blowing away agglomerated particles; CN205627898U discloses a gas distribution plate with toper air inlet, and the toper air inlet distributes according to the circumference, and the snakelike direction hood that leads is welded to toper air inlet top, eliminates the fluidization blind area through forming the whirl above the distribution plate. The invention can not be applied to the HCl oxidation fluidized bed because the protruding deconstruction of the metal hood, the deflector and the like can generate serious corrosion abrasion, and the invention has low operation elasticity, can only increase the air speed of the whole ventilation area in order to keep large particles fluidized and prevent the catalyst from leaking into the gas distribution chamber from the air inlet, enables the catalyst particles with small particle size to have higher speed, and further aggravates the abrasion of the internal components of the fluidized bed side wall area, the hood, the deflector and the like.
Therefore, it is important to develop a gas distributor suitable for high temperature and high corrosion environment in the HCl oxidation fluidized bed reactor, to overcome the non-uniform distribution of gas in the fluidized bed, and to avoid the problems of severe catalyst wear and erosion abrasion caused by local high gas velocity, and to have high operation flexibility.
Disclosure of Invention
One object of the present invention is to provide a gas distributor, which can make the fluidization in the fluidized bed uniform by reasonably controlling the air inflow of the central area and the sidewall area, and simultaneously, greatly reduce the air velocity of the air inlet hole area by the flat-top conical porous hood, reduce the catalyst abrasion, change the air injection direction of the air inlet hole from the traditional high-speed axial direct injection into radial annular air distribution, eliminate the settling dead area on the distribution plate, and reduce the abrasion of the components in the fluidized bed caused by high-speed particles. Another object of the present invention is to provide a use of a gas distributor in a fluidized bed of HCl oxidation.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a gas distributor comprises a gas distribution plate 1, wherein the gas distribution plate is divided into a circular central area 1a and a circular side wall area 1 b; the gas distribution plate is uniformly provided with gas inlet holes 2, a porous blast cap 4 is sealed and fixed above each gas inlet hole through a metal cover plate 3, and the fixing mode is welding; the porous blast cap is made of SIC (silicon carbide) porous sintering materials.
Further, the central area accounts for 60-80% of the total area of the gas distribution plate, and the sidewall area accounts for 20-40% of the total area of the gas distribution plate.
Furthermore, the aperture ratio of the air inlet holes on the gas distribution plate is 1-5%; the opening rates of the central area and the side wall area are the same, and the opening rate is calculated by the area of the outlet of the air inlet hole relative to the area of the upper surface of the gas distribution plate.
Preferably, the diameters D0 of the air inlet holes of the central area and the side wall area are the same and are 5-18 mm.
Furthermore, the porous blast cap is of a flat-top conical structure, and the included angle alpha between the inclined surface of the porous blast cap and the horizontal direction is that the central area is smaller than the side wall area; preferably, the angle α is 25-75 °.
Further, the inner diameters of the conical bottoms D1 of the central area and the conical tops D2 of the side wall areas are the same.
Further, the inner diameter D1 of the conical bottom is 2-10 times of the diameter D0 of the air inlet hole.
Further, the inner diameter D2 of the conical top is 0.5-3 times of the diameter D0 of the air inlet hole.
Further, the wall thickness h of the porous hood is that the central area is larger than the side wall area; preferably, the wall thickness h of the porous hood is 5-10 mm.
Further, the pore size of the porous hood is 50-500 μm.
The invention also provides the application of the gas distributor in the HCl oxidation fluidized bed reactor.
As mentioned above, a porous hood is fixed on each air inlet hole in a sealing way by welding a metal cover plate, and the gas enters the inner cavity of the porous hood after passing through the air inlet holes to be secondarily distributed, and then enters the fluidized bed. For a single air inlet, the ventilation area is enlarged from the sectional area of the air inlet to the surface of the whole porous hood, the local air speed is greatly reduced, meanwhile, the air injection direction of the air inlet is changed from high-speed axial direct injection to radial annular air distribution, the settling dead zone on the distribution plate is eliminated, and meanwhile, the abrasion of the components in the fluidized bed caused by high-speed particles is effectively reduced. For an industrial fluidized bed with larger diameter, because of the side wall effect, the gas quantity in the central area is high, and the gas quantity near the wall surface is low, so that the fluidization is not uniform.
The gas distributor of the invention can be applied to a fluidized bed reactor of a strong-heat-release strong-corrosion system, and is preferably applied to an HCl oxidation fluidized bed reactor.
By adopting the technical scheme, the invention has the following positive effects:
(1) the air speed of the air inlet is obviously reduced, and the air inlet mode is changed from air inlet direct injection into radial annular air distribution, so that the abrasion and pulverization of the catalyst and the scouring and abrasion of the wall and the inner components of the reactor are greatly reduced;
(2) the gas distribution in the fluidized bed is optimized, the fluidization dead zone in the fluidized bed is eliminated, and the hardening of catalyst particles and the loss of active components caused by local overheating during fluidization are effectively avoided;
(3) the porous material flat-top conical structure blast cap is used, the fluidization dead zone of the distribution plate is eliminated, material leakage and air inlet blockage caused by low air speed of the air inlet are avoided, the ventilation quantity can be adjusted in a large range, the operation elasticity is large, and the stability is high;
(4) the porous material is used as a secondary air distribution hood material, does not have raised metal components such as a metal guide plate, a metal hood and the like, is particularly suitable for an HCL oxidation system, and has the advantages of simple and firm structure, convenience in maintenance and low manufacturing cost;
(5) the gas distributor is not easy to block, is high-temperature resistant and corrosion resistant, and obviously improves the operation flexibility and the production period of the fluidized bed.
Drawings
Fig. 1 is a schematic longitudinal sectional structure of the distributor of the present invention.
Fig. 2 is a partially enlarged schematic view of fig. 1.
In the figure, 1, a gas distribution plate; 1a, a central region; 1b, a side wall area; 2. an air inlet; 3. a metal cover plate; 4. a porous blast cap.
Detailed Description
The present invention is further illustrated by the accompanying drawings and the specific embodiments thereof, which are given by way of illustration only and do not limit the scope of the invention.
Example 1
The gas distributor according to the invention was fitted in a pilot-plant HCl-oxidation fluidized-bed reactor having a diameter of 1m and a height of 6 m. As shown in fig. 1 and 2, the gas distributor comprises a gas distribution plate, wherein a central area 1a is a circular area and is positioned at the center of the gas distribution plate and accounts for 60% of the total area of the gas distribution plate, and a side wall area 1b is a circular ring and accounts for 40% of the total area of the gas distribution plate; the aperture ratio of the air inlet hole is 1.5 percent. The porous blast cap above the air inlet hole is made of SIC porous sintered material.
The diameter D0 of inlet port is 13mm, and porous hood passes through Ni600 metal cover plate welded closure and fixes on the gas distribution board. The inner diameter D1 of the conical bottom of the porous blast cap is 40mm, the inner diameter D2 of the conical top is 10mm, and the aperture size of the SIC material is 100 mu m; the included angles alpha between the inclined surfaces of the porous hoods on the central area 1a and the side wall area 1b and the horizontal direction are 45 degrees and 50 degrees respectively, and the wall thickness h of the porous hoods on the central area 1a and the side wall area 1b is 10mm and 7mm respectively.
A continuous exothermic reaction for preparing chlorine gas by oxidizing HCl is carried out in the fluidized bed reactor, and a copper catalyst with the particle size distribution of 200 meshes to 325 meshes is adopted. The composition of the reaction gas is: 44.0 mol% HCl, 46.0 mol% O2，10.0mol％N2. The reaction pressure is 0.3MPa, the temperature is 410 ℃, and the reaction gas flow is 1000Nm3H is used as the reference value. The pressure drop across the distributor plate was 0.02MPa and the pressure drop measured in the fluidized bed was 0.11 MPa. When the fluidized bed is in operation, the fluidizing gas passes through the gas distributor from the gas distribution chamber at the lower end through the gas inlet holes.
The reactor is continuously operated for 31 days, the bed pressure drop is always kept stable in the process, and the bed temperatures of the fluidized bed at different heights do not fluctuate obviously. And after the reactor is stopped, a manhole is opened for inspection, the wall surface of the fluidized bed has no erosion sign, and the catalyst particles are not hardened and pulverized.
Example 2
The gas distributor according to the invention was fitted in an industrial HCl oxidation fluidized-bed reactor having a diameter of 4m and a height of 22 m. The gas distributor comprises a gas distribution plate, wherein a central area 1a is circular and is positioned at the center of the gas distribution plate and accounts for 75% of the total area of the gas distribution plate, and a side wall area 1b is circular and accounts for 25% of the total area of the gas distribution plate; the aperture ratio of the air inlet hole is 1.3 percent. The porous blast cap above the air inlet hole is made of SIC porous sintered material.
The diameter D0 of inlet port is 18mm, and porous hood passes through Ni600 metal cover plate welded closure and fixes on the gas distribution board. The inner diameter D1 of the conical bottom of the porous blast cap is 40mm, the inner diameter D2 of the conical top is 20mm, and the aperture size of the SIC material is 100 mu m; the included angles alpha between the inclined surfaces of the porous hoods on the central area 1a and the side wall area 1b and the horizontal direction are 45 degrees and 55 degrees respectively, and the wall thickness h of the porous hoods on the central area 1a and the side wall area 1b is 12mm and 8mm respectively.
In the fluidized bed, a continuous exothermic reaction for producing chlorine gas by oxidation with HCl was carried out, and 110 tons of a copper-based catalyst having a particle size distribution of 200 to 325 mesh was packed. The composition of the reaction gas is: 30.0 mol% HCl, 40.0 mol% O2，30.0mol％N2Reaction pressure of 0.45MPa, temperature of 395 ℃ and reaction gas flow of 16000Nm3H is used as the reference value. The pressure drop across the distributor plate was 0.04MPa and the pressure drop measured in the fluidized bed was 0.15 MPa. When the fluidized bed works, the fluidizing gas passes through the gas distributor from the gas distribution chamber at the lower end through the gas inlet holes.
The reactor continuously works for 180 days, the pressure drop of a bed layer is always kept stable in the process, the temperatures of the bed layers at different heights of the fluidized bed are not obviously fluctuated, the accumulated addition of the catalyst is 900kg, and the average addition per day is 5 kg. And after the reactor is stopped, a manhole is opened for inspection, the wall surface of the fluidized bed has no erosion sign, and the catalyst particles are not hardened and pulverized.
Comparative example 1
This comparative example differs from example 2 in that: an industrial HCl oxidation fluidized bed reactor with the diameter of 4m and the height of 22m is provided with a common gas distribution plate with the aperture ratio of 1.3 percent, air inlets with the same structure size are uniformly distributed on the distribution plate, the diameter of each orifice is 18mm, and a metal punching blast cap is arranged above each vent hole; the metal perforating hood is conical.
In the fluidized bed, continuous exothermic reaction of HCl oxidation to chlorine gas is carried out110 tons of copper-based catalyst having a particle size distribution of 200 to 325 mesh was charged. The composition of the reaction gas is: 30.0 mol% HCl, 40.0 mol% O2，30.0mol％N2Reaction pressure of 0.45MPa, temperature of 395 ℃ and reaction gas flow of 16000Nm3H is used as the reference value. The pressure drop across the distributor plate was 0.04MPa and the pressure drop measured in the fluidized bed was 0.15 MPa. When the fluidized bed works, the fluidizing gas passes through the gas distributor from the gas distribution chamber at the lower end through the gas inlet holes.
The oxidation reaction can be continuously carried out for only 8 days, the bed pressure drop is reduced and the temperature fluctuation of the fluidized bed is obvious when the reactor is operated for 6 days, and the reactor is emergently stopped when the temperature of the reactor is reduced in a cliff mode when the reactor is operated for 8 days. And after the reactor is stopped, the manhole is opened for inspection, the metal perforated blast caps arranged above the vent holes are completely worn and disappear, the catalyst particles are seriously pulverized and hardened, and a large amount of catalyst leaks to the gas distribution chamber at the lower end and must be manually cleaned.
The use effects of examples 1, 2 and comparative example 1 show that: the gas distribution plate of the invention not only improves the heat transfer and mass transfer efficiency of the fluidized bed, but also reduces the erosion abrasion of the fluidized bed and the catalyst pulverization, greatly improves the operation stability of the device, and is very suitable for the HCl oxidation fluidized bed reactor of a strong corrosion and strong heat release reaction system.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.
Claims (6)
1. A gas distributor, comprising a gas distribution plate (1) divided into a circular central area (1a) and a circular sidewall area (1 b); the gas distribution plate is uniformly provided with gas inlet holes (2), and a porous blast cap (4) is sealed and fixed above each gas inlet hole through a metal cover plate (3); the porous blast cap is made of a SIC porous sintered material;
the central area accounts for 60-80% of the total area of the gas distribution plate, and the side wall area accounts for 20-40% of the total area of the gas distribution plate;
the diameters D0 of the air inlet holes in the central area and the side wall area are the same and are 5-18 mm;
the porous blast cap is of a flat-top conical structure, and the included angle alpha between the inclined surface of the porous blast cap and the horizontal direction is that the central area is smaller than the side wall area; the included angle alpha is 25-75 degrees;
the conical bottom inner diameters D1 of the central area and the side wall area are the same, and the conical top inner diameters D2 of the central area and the side wall area are the same;
the wall thickness h of the porous blast cap is that the central area is larger than the side wall area; the wall thickness h of the porous blast cap is 5-10 mm.
2. The gas distributor of claim 1, wherein the gas inlets have an opening ratio of 1-5% on the gas distribution plate.
3. The gas distributor of claim 1, wherein the conical base inner diameter D1 is 2-10 times the inlet hole diameter D0.
4. The gas distributor of claim 1, wherein the conical tip inner diameter D2 is 0.5-3 times the inlet hole diameter D0.
5. The gas distributor according to any one of claims 1 to 4, wherein the pore size of the porous hood is 50 to 500 μm.
6. Use of a gas distributor according to any of claims 1 to 5 in a fluidized bed reactor for the oxidation of HCl.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010233613.5A CN111298728B (en) | 2020-03-30 | 2020-03-30 | Gas distributor and application thereof in HCl (hydrochloric acid) oxidation fluidized bed |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010233613.5A CN111298728B (en) | 2020-03-30 | 2020-03-30 | Gas distributor and application thereof in HCl (hydrochloric acid) oxidation fluidized bed |
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| CN111298728A CN111298728A (en) | 2020-06-19 |
| CN111298728B true CN111298728B (en) | 2022-03-08 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US3494046A (en) * | 1967-11-20 | 1970-02-10 | Union Carbide Corp | Fluid bed drying system |
| CN102760503B (en) * | 2011-04-28 | 2015-02-18 | 清华大学 | Gas distribution device and particle coating method |
| CN206121710U (en) * | 2016-07-04 | 2017-04-26 | 茂名重力石化装备股份公司 | Spill airflow distribution plate and reactor thereof |
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