CN108654526B - Reactor capable of reducing back mixing and used for preparing olefin through alkane dehydrogenation and preparation method - Google Patents

Reactor capable of reducing back mixing and used for preparing olefin through alkane dehydrogenation and preparation method Download PDF

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CN108654526B
CN108654526B CN201710213552.4A CN201710213552A CN108654526B CN 108654526 B CN108654526 B CN 108654526B CN 201710213552 A CN201710213552 A CN 201710213552A CN 108654526 B CN108654526 B CN 108654526B
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CN108654526A (en
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李春义
王国玮
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China University of Petroleum East China
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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
    • B01J8/1809—Controlling processes
    • 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
    • B01J8/0015—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
    • B01J8/004—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor by means of a nozzle
    • 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
    • B01J8/1845—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised
    • B01J8/1863—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles with particles moving upwards while fluidised followed by a downward movement outside the reactor and subsequently re-entering it
    • 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
    • B01J8/26—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 two or more fluidised beds, e.g. reactor and regeneration installations
    • 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
    • B01J8/38—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 fluidised bed containing a rotatable device or being subject to rotation or to a circulatory movement, i.e. leaving a vessel and subsequently re-entering it
    • B01J8/384—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 fluidised bed containing a rotatable device or being subject to rotation or to a circulatory movement, i.e. leaving a vessel and subsequently re-entering it being subject to a circulatory movement only
    • B01J8/388—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 fluidised bed containing a rotatable device or being subject to rotation or to a circulatory movement, i.e. leaving a vessel and subsequently re-entering it being subject to a circulatory movement only externally, i.e. the particles leaving the vessel and subsequently re-entering it
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C07C5/3332—Catalytic processes with metal oxides or metal sulfides
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00548—Flow
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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Abstract

The utility model provides a reaction unit of alkane catalytic dehydrogenation, includes reaction section and reactor settling section, the reactor settling section is located the upper portion of reaction section, the diameter from the bottom up of reaction section diminish gradually, the catalyst regeneration pipe chute stretches into in the reaction section, and the exit end of catalyst regeneration pipe chute is located the lower part of reaction section, feeding distribution device is located the below of the exit end of the catalyst regeneration pipe chute in the reaction section. The reactants and the catalyst in the reactor flow upwards in a parallel flow manner, so that the uniformity of temperature distribution in the reactor can be effectively improved, and local high temperature is avoided, thereby reducing thermal reaction; and the reactor is gradually reduced in diameter along the flowing direction of the fluid, so that the secondary conversion of olefin caused by back mixing is reduced, and the yield and the selectivity of the olefin are improved. The high-temperature regenerant is directly sprayed into the bottom of the dense-phase bed of the reactor, so that the high-temperature regenerant is favorable for quickly mixing the high-temperature catalyst with the catalyst in the reactor, the formation of local high temperature in the bed is avoided, and the dense-phase fluidized catalyst is also favorable for terminating the transfer of free radicals, thereby reducing thermal reaction and improving the selectivity of alkane dehydrogenation and olefin.

Description

Reactor capable of reducing back mixing and used for preparing olefin through alkane dehydrogenation and preparation method
Technical Field
The invention relates to a circulating fluidized bed reactor, in particular to a circulating fluidized bed alkane dehydrogenation reaction device, and more particularly relates to an alkane dehydrogenation reaction device capable of reducing back mixing.
Background
Olefins and diolefins (ethylene, propylene, butylene, isobutylene, isoprene, butadiene, etc.) find wide application in synthetic resins, plastics, high octane gasoline blending components (methyl tert-butyl ether, methyl tert-amyl ether and alkylate), and other high value added products. Besides the production of olefins by steam cracking of hydrocarbons (e.g. ethane steam cracking, naphtha steam cracking), catalytic cracking of olefins (e.g. Superflex technology), catalytic cracking of heavy oils (e.g. TMP, DCC technology) and catalytic pyrolysis of heavy oils (e.g. CPP technology), the catalytic dehydrogenation of alkanes is an important technical route for the production of olefins and diolefins.
The alkane dehydrogenation is increasingly paid attention to by people as an important way for reasonably utilizing rich low-carbon alkane resources and preparing low-carbon olefins with high added values.
The dehydrogenation of alkanes is a relatively strong endothermic reaction, such as propane and isobutane,
C3H8→C3H6+H2ΔHo＝124.3kJ/mol
i-C4H10→i-C4H8+H2ΔHo＝117.6kJ/mol
the reaction heat at 0.1MPa and 25 deg.C is up to 124.3 and 117.6kJ/mol respectively. Whatever type of reactor is used, how to efficiently supply heat to the reaction is a matter that must be carefully considered.
Dehydrogenation reactions of alkanes are limited by thermodynamic equilibrium. Under the same temperature condition, the larger the molecule of alkane is, the higher the equilibrium conversion rate is; the higher the temperature, the higher the equilibrium conversion for the same alkane. If the catalytic dehydrogenation method is adopted to prepare ethylene, the method is limited by thermodynamic equilibrium, and the conversion per pass is too low, so that the conventional ethane dehydrogenation adopts a steam pyrolysis technology, and the reaction is carried out at a high temperature of over 800 ℃. Since the catalytic dehydrogenation of propane, butane, etc. can obtain economically acceptable per pass conversion and olefin selectivity under suitable temperature conditions, the catalytic dehydrogenation is generally used for producing propylene, butene or butadiene by dehydrogenation of propane and butane.
Oxidative dehydrogenation, as another route of alkane dehydrogenation, although thermodynamic equilibrium limitation can be broken, alkane conversion rate is greatly improved, and coke yield is reduced, due to introduction of oxygen species, deep oxidation reaction is difficult to control, and a large amount of COx and H are generated2O, the selectivity of the target product olefin is poor, and the waste of raw materials is caused. Although researchers have conducted extensive research on this, no significant improvement in olefin selectivity was observed, and this problem was difficult to break through in the short term.
The industrialized dehydrogenation technology at present adopts a catalytic dehydrogenation route, and the adopted catalysts are Pt-based and Cr2O3A base catalyst. The Pt is expensive, the application of the Pt catalyst dehydrogenation process is limited by high investment and catalyst use cost, and the process is reasonable in economy only in countries or regions with abundant and low-price alkane resources. In addition, the Pt catalyst is very resistant to sulfur, arsenic and other poisonsThe catalyst is sensitive, therefore, the use of the catalyst requires very high impurity content in the raw material. The Pt catalyst is adopted, Pt is easy to sinter, the catalyst regeneration needs oxychlorination regeneration, and the regenerated flue gas can be discharged after being treated. The supported Cr-series catalyst has excellent dehydrogenation performance, but hexavalent chromium generated by catalyst regeneration has a strong carcinogenic effect, the production and use links of the catalyst can cause environmental pollution, and the treatment of the waste catalyst is also a difficult problem.
From the reactor point of view, fixed beds, moving beds and circulating fluidized beds are used. The alkane dehydrogenation catalyst is easy to coke and deactivate, and Pt is easy to sinter by adopting a Pt catalyst, so that the catalyst needs frequent coke burning regeneration or oxychlorination regeneration. The use of a fixed bed is obviously inconvenient to regenerate, and moving beds and fluidized beds can carry out the reaction and regeneration continuously. The Pt catalyst is expensive, the fluidized bed only can use Cr catalyst, and the Cr catalyst can bring serious pollution to the environment. The moving bed adopts the Pt catalyst, so that the catalyst has a regeneration period of several days, the reaction needs to be carried out under the hydrogen condition, the one-way conversion rate is reduced, and the energy consumption of the moving bed is very high due to the hydrogen circulation.
From the viewpoints of catalyst regeneration, heat transfer efficiency and reaction efficiency, the most suitable reactor for alkane dehydrogenation is obviously a non-circulating fluidized bed reactor, the part of the reactor adopting the circulating fluidized bed is much simpler than the technological process of a fixed bed and a moving bed, and the equipment investment of the same scale is lower. The focus of the contradiction is to develop a nontoxic and relatively inexpensive catalyst which can be used for a fluidized bed and to match a circulating fluidized bed reactor according to the property and performance characteristics of the catalyst.
In the catalyst and circulating fluidized bed reactor sector, we have conducted a great deal of research over the years.
Such as: ZL 201110123675.1 discloses a catalyst and a circulating fluidized bed reactor suitable for the performance of the catalyst, wherein a part of the catalyst in the reactor is extracted from the bottom for high-temperature afterburning regeneration, and then is mixed with the other part of the extracted catalyst and returns from the top of the reactor, so that the catalyst is burnt and regenerated, a high-temperature regenerant is used for supplying heat for the reactor, and meanwhile, the occurrence of thermal reaction caused by the fact that the high-temperature regenerant directly enters the reactor is avoided.
Chinese patent application No. CN 201510003377.7 improves the reactor, and proposes to arrange a heat exchange device in the settling section of the reactor, so as to exchange heat between the raw material and the high-temperature oil gas, rapidly cool the high-temperature oil gas, reduce the high-temperature thermal reaction, and avoid coking of the device. The CN 201510003556.0 has the problem that the reaction regeneration system is too complicated in the scheme provided by ZL 201110123675.1, a simplified circulating fluidized bed scheme is provided, and a regenerator is improved, so that the fuel can be fully combusted, and the heat exchange with a catalyst is fully realized.
For a circulating fluidized bed reactor for alkane dehydrogenation, improving the conversion per pass and olefin selectivity of alkane dehydrogenation is always a goal pursued by the art. In the reaction device, the gas phase back-mixing phenomenon also influences one of the factors of olefin selectivity and conversion rate in the paraffin dehydrogenation.
In view of this, the present application is presented.
Disclosure of Invention
The invention aims to provide a reaction device for preparing olefin by catalytic dehydrogenation of alkane, which gradually reduces the diameter along the fluid flow direction and reduces the secondary conversion of olefin caused by back mixing.
The invention also aims to provide a reaction device for preparing olefin by catalytic dehydrogenation of alkane, wherein reactants and a catalyst in a reactor of the reaction device flow upwards in a cocurrent manner, so that the uniformity of temperature distribution in the reactor can be effectively improved, and local high temperature is avoided.
It is a further object of the present invention to provide a process for the catalytic dehydrogenation of alkanes to olefins.
In order to realize the purpose, the following technical scheme is adopted:
the invention provides a reaction device for catalytic dehydrogenation of alkane, which comprises a reaction section and a reactor settling section, wherein the reactor settling section is positioned at the upper part of the reaction section, and the diameter of the cross section of the reaction section is gradually reduced from bottom to top;
the reaction device also comprises a catalyst regeneration inclined tube and a feeding distributor, wherein the catalyst regeneration inclined tube extends into the reaction section, and the feeding distributor is positioned below the outlet end of the catalyst regeneration inclined tube in the reaction section.
According to the reaction device provided by the invention, the catalyst and the reactant flow upwards in a parallel flow manner in the reaction section, the reaction section in the flow direction is a diameter-reducing process, secondary conversion caused by product back-mixing is reduced, the heat of the high-temperature catalyst can be fully utilized, and thermal reaction caused by local high temperature is avoided, so that the selectivity of olefin is improved.
A preparation method for preparing olefin by alkane catalytic dehydrogenation by using the reaction device comprises the steps that raw materials enter a reaction section from a feeding distributor, the raw materials and a catalyst flow upwards in a parallel flow mode, and the raw materials and the catalyst are in contact with each other to carry out catalytic reaction, wherein the lower ends of the reaction section and the settling section of a reactor are positioned at the cross section of the same horizontal plane, the average linear velocity of gas is controlled to be 0.3-10.0 m/s, the reaction temperature is preferably controlled to be 500-650 ℃, and the mass space time of the reaction is 0.1-15 hours.
The method for preparing the olefin by catalytic dehydrogenation of the alkane performed by the reaction device has the advantage that the selectivity of the obtained product olefin is remarkably improved.
Compared with the prior art, the application has the advantages that:
the reactants and the catalyst in the reactor flow upwards in a parallel flow manner, so that the uniformity of temperature distribution in the reactor can be effectively improved, and local high temperature is avoided, thereby reducing thermal reaction and improving the selectivity of alkane dehydrogenation and olefin; and the reactor is gradually reduced in diameter along the flowing direction of the fluid, so that the secondary conversion of olefin caused by back mixing is reduced, and the yield and the selectivity of the olefin are improved. The high-temperature regenerant is directly sprayed into the bottom of the dense-phase bed of the reactor, so that the high-temperature regenerant is favorable for quickly mixing the high-temperature catalyst with the catalyst in the reactor, the formation of local high temperature in the bed is avoided, and the dense-phase fluidized catalyst is also favorable for terminating the transfer of free radicals, thereby reducing thermal reaction and improving the selectivity of alkane dehydrogenation and olefin.
Drawings
FIG. 1 one embodiment of a reaction apparatus for catalytic dehydrogenation of alkanes to olefins according to the present application
FIG. 2 one embodiment of a combination of a reaction apparatus and a regeneration apparatus for catalytic dehydrogenation of alkanes to olefins
Detailed Description
The reaction apparatus for producing an olefin by catalytic dehydrogenation of an alkane and the method for producing an olefin by catalytic dehydrogenation of an alkane according to the present invention will be described in further detail below. And do not limit the scope of the present application, which is defined by the claims. Certain disclosed specific details provide a thorough understanding of various disclosed embodiments. One skilled in the relevant art will recognize, however, that embodiments may be practiced without one or more of the specific details, with other materials, etc.
Unless the context requires otherwise, in the description and claims, the terms "comprise," comprises, "and" comprising "are to be construed in an open-ended, inclusive sense, i.e., as" including, but not limited to.
Reference in the specification to "an embodiment," "another embodiment," or "certain embodiments," etc., means that a particular described feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, "an embodiment," "another embodiment," or "certain embodiments" do not necessarily all refer to the same embodiments. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, the features disclosed are merely generic examples of equivalent or similar features.
A reaction device for catalytic dehydrogenation of alkane comprises a reaction section and a reactor settling section, wherein the reactor settling section is positioned at the upper part of the reaction section, and the diameter of the cross section of the reaction section is gradually reduced from bottom to top;
the reaction device also comprises a catalyst regeneration inclined tube and a feeding distributor, wherein the catalyst regeneration inclined tube extends into the reaction section, and the feeding distributor is positioned below the outlet end of the catalyst regeneration inclined tube in the reaction section.
Preferably, the outlet end of the catalyst regeneration inclined tube is positioned at the lower part of the reaction section.
In a gas-phase and solid-phase flow mixing reaction system, back mixing, also known as back mixing, is a mixing phenomenon. In a narrow sense, it refers to the mixing of materials caused by movement in a continuous process opposite to the main flow direction. In the circulating bed fluidized reaction process of alkane catalytic dehydrogenation, the gas phase back-mixing phenomenon is also an important factor influencing the selectivity and conversion rate of olefin prepared by alkane dehydrogenation. In this application, the catalyst outlet end is located in the lower portion of the reaction zone. In the reaction section, the catalyst and the reactant flow upward simultaneously, and the linear velocity of the gas in the reaction section is gradually increased along with the upward gradual diameter reduction of the reaction section, namely the diameter of the cross section of the reaction section is gradually reduced from bottom to top. Therefore, the method is favorable for reducing the back mixing phenomenon of gas, thereby reducing the secondary conversion of olefin generated by alkane dehydrogenation and improving the selectivity of olefin.
In one embodiment, a catalyst riser is arranged in the reaction section, and the outlet end of the catalyst regeneration inclined tube in the reaction section is connected with the catalyst riser. Preferably, the outlet end of the catalyst regeneration inclined tube is connected with the side wall of the catalyst riser.
In certain embodiments, the outlet end of the catalyst riser inside the reaction section is located in the lower portion of the reaction section.
In some embodiments, a pre-lift pipe is further disposed in the catalyst lift pipe, one end of the pre-lift pipe for conveying the catalyst lift medium is located outside the reaction device, and the other end of the pre-lift pipe is disposed in the catalyst lift pipe.
When the catalyst regeneration inclined pipe is connected with the catalyst lifting pipe, the high-temperature regenerated catalyst firstly enters the catalyst lifting pipe in the reaction section through the regeneration inclined pipe. On the one hand, this arrangement can directly supply heat for the endothermic alkane dehydrogenation reaction, which is the most efficient.
On the other hand, if the high-temperature catalyst is directly contacted with oil gas, the defects of local high temperature, serious thermal reaction, olefin selectivity reduction and the like are caused. The preheated alkane raw material flows upwards from the bottom of the reactor and flows upwards together with the high-temperature catalyst sprayed out from the outlet of the riser, so that the full contact and uniform mixing of the raw material and the catalyst are facilitated, the strong endothermic effect of the low-temperature raw material and the dehydrogenation reaction is further facilitated, the temperature of the catalyst is rapidly reduced, the thermal reaction caused by local high temperature is avoided, and the dehydrogenation selectivity is improved. In addition, the high temperature catalyst is sprayed into the dense bed, and the high catalyst density is beneficial to terminating the transfer of free radicals, reducing thermal reaction and improving the selectivity of dehydrogenated olefin.
In the present application, the diameter of the cross section of the reaction section gradually decreases from bottom to top, including various ways, such as the diameter of the cross section of the reaction section continuously decreases; or, starting from the lower end of the reaction section, reducing the diameter and changing, then carrying out equal-diameter transition, and then reducing the diameter and changing sequentially until the upper part of the reaction section is connected with the lower end of the settling section of the reactor.
In certain embodiments, the upper portion of the reaction section extends into the settling section of the reactor.
The diameter of the cross section of the reaction section extending into the settling section of the reactor can be equal diameter from bottom to top, or can be reduced from bottom to top by a section and then extend in an equal radial direction. How long the specific reaction section extends into the settling section of the reactor can be set according to actual process requirements, and the catalyst and the oil gas can be conveniently separated.
In certain embodiments, the catalyst riser and the lift media pipe are all equal diameter pipes in the present application.
In certain embodiments, the lift medium tubes extend into the riser through the bottom or side wall of the catalyst riser.
The outlet end of the catalyst riser is positioned at the lower part of the reaction section. Here, the lower part of the reaction section means a space near the bottom end of the reaction section.
In certain embodiments, the outlet end of the pre-riser is located above the upper edge of the lower opening of the regenerator chute. Typically, the catalyst riser is vertically disposed and the regeneration chute is connected to the sidewall of the catalyst riser so that the outlet end of the regeneration chute is the opening in the sidewall of the catalyst riser.
Preferably, in the axial direction, the outlet end of the pre-lift pipe is higher than the upper edge of the discharging opening of the regeneration inclined pipe by a distance of not more than 0.1 m. More preferably, the outlet end of the pre-lifting pipe and the upper edge of the discharging opening of the regeneration inclined pipe are positioned on the same horizontal plane.
In certain embodiments, the reaction section is circular in cross-section and the catalyst riser is disposed coaxially with the reaction section.
The bottom of the catalyst riser can be either closed or open. As long as in the catalyst in the riser in the lifting medium constantly upwards in the process of operation, in regeneration pipe chute feed opening near can form the negative pressure can increase the catalyst from the regenerator into the driving force of reactor.
In certain embodiments, the bottom of the catalyst riser is closed.
According to the method, a catalyst lifting pipe is arranged in a reaction section, a regeneration inclined pipe penetrates through the reaction section to be connected with the catalyst lifting pipe, and negative pressure is formed near a discharging port of the regeneration inclined pipe in the process that a regeneration catalyst continuously moves upwards along the lifting pipe under the suction and pushing of a lifting medium, so that the pushing force of the catalyst entering a reactor from a regenerator is increased; in addition, under the pushing of the lifting medium, the catalyst is sprayed out from the upper port of the lifting pipe at a high speed, so that the high-temperature catalyst is favorably and quickly mixed with the catalyst in the reaction section, and the formation of local high temperature in a bed layer is avoided. More preferably, the pre-riser outlet may be located on the central axis of the riser, in order to ensure good pumping and pushing action of the pre-riser on the catalyst.
And determining the outlet position of the regeneration inclined pipe according to the angle of the regeneration inclined pipe, the length of the riser and the outlet position of the riser. In the present application, the distance from the upper edge of the opening of the catalyst riser to the outlet of the catalyst riser at the point where the regeneration chute is connected to the catalyst riser is about 0.1m to 2.0m, preferably 0.3m to 1.0 m.
In the reactor of the present application, the diameter of the settling section is larger than that of the reaction section in order to achieve the purpose of reducing the gas velocity to settle the catalyst.
In certain embodiments, a feed distributor is positioned within the reaction zone below the catalyst riser. The feed system is near the bottom of the reactor. Preferably, the feed distributor is one or more annular pipes arranged on the same plane, and nozzles are arranged on the annular pipes.
Wherein the direction of the nozzle may be in an upward or downward direction, preferably, in a downward direction.
In order to ensure that the catalyst and the raw materials are in sufficient contact reaction in the reaction section, a grid or a porous distribution plate is arranged in the reaction section and at the upper part of the feeding distributor. Preferably a distribution plate having an open porosity of not more than 50%.
In some embodiments, the distance between two adjacent layers of grids or porous distribution plates arranged in the reaction section and at the upper part of the feed inlet is 0.01-2.0 m; preferably, 0.1 to 0.7 m. The distribution of gas and catalyst is continuously changed through the arrangement of the grid or the porous distribution plate, so that the full contact reaction of raw materials and the catalyst is promoted, and the gas-solid contact and reaction efficiency are improved.
An oil gas outlet is arranged at the top end of the reaction device, a cyclone separator is arranged in the settling section of the reactor, and the cyclone separator is connected with the oil gas outlet.
In the application, the spent catalyst can be extracted from the side surface of the settling section of the reactor close to the bottom and enters the regenerator through a spent inclined tube. The spent catalyst can directly enter a dense bed of a regeneration section and can also enter a settling section of a regenerator. Preferably, the spent catalyst enters the settling section of the regenerator. The spent catalyst enters the settling section of the regenerator and is in a dilute phase fluidized state, which is beneficial to quickly burning off coke.
The reaction device for preparing olefin by alkane dehydrogenation can be combined with the catalyst regenerator disclosed by the prior art to carry out circulating fluidized dehydrogenation reaction.
In some modes, the catalyst regenerator comprises a catalyst regeneration section and a regeneration settling section, wherein the regeneration section is positioned at the lower part of the settling section, and the lower part of the settling section of the reactor is connected with the lower part of the regeneration settling section through a to-be-regenerated inclined pipe; one end of the regeneration inclined tube is connected with the catalyst lifting tube, and the other end of the regeneration inclined tube is connected with the bottom of the regeneration section.
The preparation method of the olefin by alkane dehydrogenation by using the reaction device for preparing the olefin by alkane dehydrogenation comprises the following steps that raw materials enter a reaction section from a feeding distributor, the raw materials and a catalyst flow upwards in a parallel flow mode and are in contact with each other to perform catalytic reaction, wherein the lower ends of the reaction section and the settling section of a reactor are positioned at the cross section of the same horizontal plane, the average linear velocity of gas is controlled to be 0.3-10.0 m/s, the reaction temperature is preferably controlled to be 500-650 ℃, and the mass space time of the reaction is 0.1-15 hours.
On the other hand, in the reaction zone, the average linear velocity of the gas at the outlet cross section of the catalyst riser is controlled to be 0.01 to 3m/s, preferably 0.2 to 0.7 m/s. In the diameter-reduced reaction section, the linear velocity of the gas in the reaction section can be gradually increased, which is beneficial to reducing the back mixing of the gas.
In some embodiments, the reaction temperature is controlled between 550 ℃ and 620 ℃.
In this application, the reaction temperature within the reaction zone is the average temperature of the reaction zone. The average temperature is determined by arranging 5-10 temperature measuring points at different axial and radial positions in the reaction section, and the average value of the temperature measuring points is the reaction temperature in the reaction section.
In some embodiments, the mass space time for the reaction is 1 to 8 hours.
The pressure at the top of the settling section of the reactor is controlled to be-0.01 to 0.1MPa, preferably 0 to 0.05MPa (Table).
In some embodiments, the superficial gas velocity in the riser is between 0.5 and 20m/s, preferably between 3 and 10 m/s.
In some embodiments, the linear velocity of the lifting medium at the outlet of the lifting medium pipe is controlled to be 5-50 m/s, preferably 15-30 m/s.
In the present application, the lifting medium may be a dehydrogenation feedstock, steam, nitrogen, hydrogen, dry gas or other small hydrocarbon, and preferably a dehydrogenation feedstock or nitrogen.
The catalyst regeneration device provided in this application, including catalyst regeneration section and regeneration settling section, the regeneration settling section is located catalyst regeneration section upper portion, is equipped with the external circulating pipe between regeneration settling section and catalyst regeneration section.
The external circulation pipe is a pipeline which is arranged outside the regeneration settling section and the catalyst regeneration section and is communicated with the regeneration settling section and the catalyst regeneration section.
The external circulation pipe is arranged to pump out a part of the high-temperature catalyst entering the sedimentation section of the regenerator and return the part of the high-temperature catalyst to the bottom of the regenerator through the external circulation pipe. Therefore, the problem that the operation safety of the device is influenced due to flameout caused by excessively low temperature at the bottom of the regenerator can be effectively avoided; meanwhile, the sintering of the catalyst caused by overhigh local temperature in the bed layer can be avoided.
In certain embodiments, one end of the external circulation tube is connected to the lower side of the catalyst regeneration section and the other end is connected to the lower side of the regeneration settling section.
A layer of porous distribution plates or grids, preferably grids, is arranged in the dense phase section of the catalyst regeneration section at intervals of 0.01-2 m, preferably 0.1-0.7 m. Can ensure the burning effect of the catalyst and promote the heat transfer of gas phase and solid phase.
The term "dense phase section of the catalyst regeneration section" is a term commonly used in the chemical industry, also known as dense phase fluidization section, and is the main zone of the catalyst regeneration reaction, corresponding to the dilute phase fluidization section.
The lower part of the dense phase section of the catalyst regeneration section is a stripping section of the regeneration section. A herringbone baffle or other internal components for promoting the mass transfer of gas phase and solid phase are arranged in the gas stripping section of the catalytic section. Thus, the gas stripping effect can be ensured, and the amount of flue gas carried by the catalyst can be reduced as much as possible.
The stripping medium may be steam, nitrogen, dry gas or other gas which does not affect the performance of the catalyst dehydrogenation reaction
The catalyst regeneration device provided by the application can be used together with all dehydrogenation reaction devices in the prior art. For the dehydrogenation of two or more raw materials with certain difference in reaction condition, two or more reaction devices can share one regeneration device, so that the reaction conditions can be set according to the reaction requirements of specific raw materials. The number of the reaction apparatus is not limited in theory, but it is preferable that the number of the reactors is not more than two in view of the workability in the engineering.
The catalyst regeneration method using the catalyst regeneration device comprises the following steps:
(1) the spent catalyst and the fuel are combusted in the regeneration section of the regeneration device at the temperature of 600-850 ℃,
(2) the catalyst in the regeneration section enters the settling section under the pushing of the flue gas, wherein part of the high-temperature catalyst entering the settling section returns to the regeneration section through an external circulation pipe, preferably returns to the bottom of the regeneration section and is combusted together with the catalyst in the regeneration section again.
Preferably, the fuel is combusted in a regeneration section of the regeneration device under the condition of temperature of 630-750 ℃.
The fuel can be gas fuel or liquid fuel without sulfur and metal.
In the present application, the fuel is injected into the dense phase section of the regeneration section at multiple points, either from different axial locations or only at a certain axial location, preferably multiple points, with the lowest injection point being above the air distribution tubes.
Compared with the prior art, the application has the advantages that:
1) the reactants and the catalyst in the reactor flow upwards in a parallel flow mode, so that the uniformity of temperature distribution in the reactor can be effectively improved, and local high temperature is avoided, thereby reducing thermal reaction and improving the selectivity of alkane dehydrogenation olefin.
2) The reactor is gradually reduced in diameter along the flowing direction of the fluid, so that the secondary conversion of olefin caused by back mixing is reduced, and the yield and the selectivity of the olefin are improved.
3) The high-temperature regenerant is directly sprayed into the bottom of the dense-phase bed of the reactor, so that the high-temperature regenerant is favorable for quickly mixing the high-temperature catalyst with the catalyst in the reactor, the formation of local high temperature in the bed is avoided, and the dense-phase fluidized catalyst is also favorable for terminating the transfer of free radicals, thereby reducing thermal reaction and improving the selectivity of alkane dehydrogenation and olefin.
4) The pre-lifting medium is ejected from the position near the upper edge of the regeneration inclined tube catalyst feed opening at a high speed, negative pressure can be formed near the feed opening, the driving force of the catalyst entering the reactor from the regenerator is increased, and the flexibility of adjusting the catalyst circulation amount is increased.
5) The spent agent directly enters a settling section of the regenerator, and the dilute-phase fluidization is favorable for quick scorching of the spent agent.
6) After-burning in the dense-phase fluidization section of the regenerator, the catalyst and the fuel have long residence time in the regenerator, which is beneficial to fully burning off coke on the catalyst, ensuring the full combustion of the fuel, and simultaneously, being beneficial to fully transferring heat of gas phase and solid phase, and improving the utilization rate of energy.
7) The catalyst external circulation pipe is adopted to circulate the high-temperature catalyst in the sedimentation section of the regenerator to the bottom of the regenerator, so that flameout of the bottom of the regenerator due to too low temperature can be avoided, potential safety hazards caused by afterburning are eliminated, and partial high temperature can be avoided to cause catalyst sintering.
Example 1
This example illustrates the use of a catalytic alkane dehydrogenation reactor as provided herein in conjunction with a catalyst regeneration unit as provided herein, with reference to figures 1 and 2. These two units may be used separately, in combination with other prior art reaction units or catalyst regeneration units, respectively.
The reaction device for catalytic dehydrogenation of alkane shown in the attached figure 1 comprises a reaction section 10 and a reactor settling section 11, wherein the reactor settling section 11 is positioned at the upper part of the reaction section 10, the diameter of the cross section of the reaction section 10 is gradually reduced from bottom to top, a catalyst regeneration inclined tube 5 extends into the reaction section 10, and the outlet end of the catalyst regeneration inclined tube 5 is positioned at the lower part of the reaction section 10. In this embodiment, the diameter of the cross-section of the reaction section 10 becomes smaller continuously from the bottom to the top.
In the lower part of the reaction section 10, a catalyst riser 17 is provided. In the reaction section 10, a catalyst regeneration inclined tube 5 passes through the wall of the reaction section and enters the reaction section to be connected with a catalyst lifting tube 17, and a pre-lifting tube 3 for conveying a lifting medium is arranged in the catalyst lifting tube 17. The catalyst riser is closed at the bottom and the pre-riser 3 extends into the riser 17 through the bottom or side wall of the catalyst riser 17. The distance between the outlet end of the lifting medium pipe 3 and the upper edge of the feed opening of the regeneration inclined pipe 5 is not more than 0.1 m. More preferably, the outlet end of the lifting medium pipe and the upper edge of the discharging opening of the regeneration inclined pipe are positioned on the same horizontal plane. Therefore, in the process that the lifting medium in the lifting medium pipe continuously moves upwards, negative pressure is formed near the discharging opening of the regeneration inclined pipe, and the pushing force of the catalyst entering the reactor from the regenerator can be increased.
In this embodiment, the cross section of the reaction section 10 is circular, and the catalyst riser 17 and the pre-riser 3 in the catalyst riser are both disposed coaxially with the reaction section 10.
In the reaction section 10, a feed ring tube 4 is provided below the catalyst riser 17, on which a nozzle is provided, which can be directed in an upward or downward, preferably downward, direction. A grid or porous distribution plate is arranged in the reaction section 10 and above the feeding annular pipe 4. The distance between two adjacent layers of grids or porous distribution plates is 0.01-2.0 m; preferably, 0.1 to 0.7 m.
An oil gas outlet 12 is arranged at the top end of the reaction device, namely the settling section, a cyclone separator 16 is arranged in the settling section 11 of the reactor, and the cyclone separator 16 is connected with the oil gas outlet 12. The upper end of the reaction section 10 extends into the settling section 11 of the reactor. In this embodiment, the reaction section in the settling section 11 of the reactor is first reduced in diameter from bottom to top and then extended to the outlet at the upper end of the reaction section in an equal diameter manner.
The catalyst regeneration inclined pipe 5 is connected with the bottom of the catalyst regeneration section 1 of the regeneration device. The first end of the catalyst to-be-regenerated inclined tube 6 is connected with the side surface of the reactor settling section 11 close to the bottom, and the second end of the catalyst to-be-regenerated inclined tube 6 is connected with the catalytic regeneration settling section 15 of the regeneration device. The regenerative settling section 15 of the regeneration device is positioned at the upper part of the regeneration section 1.
An external circulation pipe 18 is arranged outside the regeneration settling section 15 and the catalyst regeneration section 1, one end of the external circulation pipe 18 is connected with the lower side part of the catalyst regeneration section 1, and the other end is connected with the lower side part of the regeneration settling section 15.
The top of the regeneration settling section 15 is provided with a flue gas outlet 13, the regeneration settling section 15 is internally provided with a cyclone separator 16, and the cyclone separator 16 is connected with the flue gas outlet 13.
The process flow for the reaction-regeneration apparatus of example 1 is as follows: the reaction raw material enters the reaction section 10 of the reaction device through the nozzle of the feeding annular pipe 4, the high-temperature regenerated catalyst flows into the catalyst lifting pipe 17, and is sprayed into the reaction section upwards along the catalyst lifting pipe 17 under the suction and pushing actions of the lifting medium. The high temperature catalyst and the raw material flow upward in the reaction section, and in the process, the raw material contacts with the catalyst to perform catalytic reaction. In the upward flowing process, because the reaction section is reduced in diameter from bottom to top, the average linear velocity of the gas is gradually increased, and the gas phase back mixing phenomenon can be effectively reduced.
Then under the drive of the lifting medium, the catalyst is carried into the settling section 11 of the reactor, and the product carrying the catalyst is separated by the cyclone separator and flows out through the oil gas outlet. The separated catalyst is finally pumped out from the side surface of the settling section of the reactor close to the bottom through a gas stripping medium 14, enters the catalyst tube 6 and then enters the settling section 15 of the regeneration device.
In the regeneration device, air 8 and fuel 9 are injected into the dense phase section of the regeneration section, fuel gas fuel can also be liquid fuel containing no sulfur and metal, coke of spent catalyst is burnt out in the regeneration section, the catalyst enters the regeneration settling section 15 under the push of flue gas, and the catalyst part in the settling section returns to the bottom of the settling section again through an external circulation pipe. The regenerated catalyst enters the catalyst lift tube in the reaction section 10 through the catalyst regeneration inclined tube 5. The above-described reaction is carried out in the reaction section 10 to realize the cyclic reaction-regeneration reaction.
Example 2:
the device of the embodiment 1 of the invention is adopted to prepare propylene by propane dehydrogenation
Raw materials: 99 wt% of propane, feed rate 0.6t/h
Catalyst: environment-friendly metal oxide catalyst ADHO-1(ZL 201110123675.1)
Reaction conditions are as follows: arranging a layer of grating every 0.5m on the catalyst bed layer in the reaction section; the average temperature of the bed layer is 600 ℃; the pressure of the settler is 0.03 MPa; when the quality is empty, 3 h; the average linear velocity of gas at the outlet section of a riser in the reaction section is 0.5 m/s; the average linear velocity of the gas at the cross section where the bottom of the settling section of the reactor is connected with the reactor is 2 m/s.
Regeneration conditions are as follows: a layer of grating can be arranged in the dense-phase section of the regenerator every 0.5 m; regenerator dense phase temperature, 700 ℃.
Structural form of the reaction-regeneration system: the invention is provided; in contrast, patent application CN 201611042006.0.
The reaction-regeneration reaction device for catalytic dehydrogenation of alkanes of patent application CN 201611042006.0 comprises:
the device comprises a reaction section and a sedimentation section, wherein the sedimentation section is positioned at the upper part of the reaction section, the sedimentation section is of an equal-diameter tank body structure, the reaction section is of an equal-diameter cylindrical structure, and the diameter of the reaction section is smaller than that of the sedimentation section. The lower part of the reaction section is a reducing section (stripping section) which is connected with a catalyst to-be-regenerated inclined tube, and a baffle is arranged in the reducing section.
The inside of the reaction section is provided with a catalyst lifting pipe, the outlet of the catalyst regeneration inclined pipe in the reaction section is connected with the catalyst lifting pipe, and a lifting medium pipe for conveying lifting medium is arranged in the catalyst lifting pipe. The reaction section and the lifting medium pipe are both of cylindrical structures and are coaxially arranged. The bottom of the lifting medium pipe is closed, and the lifting medium pipe extends into the lifting pipe through the bottom or the side wall of the catalyst lifting pipe. The outlet end of the lift media tubes is located near, preferably at the same level as, or slightly above the outlet of the regeneration chute at the highest elevation of the outlet end of the catalyst regeneration chute.
The lower end of the reaction section is provided with a feeding annular pipe, the annular pipe is provided with a nozzle, and the direction of the nozzle faces downwards. A grid or a porous distribution plate is arranged in the reaction section and at the upper part of the feeding annular pipe. The diameter of the settling section is larger than that of the reaction section, and the ratio of the maximum diameter of the settling section to the diameter of the reaction section is 4/1-1.1/1.
The reactor of CN 201611042006.0 can be used in combination with any catalyst regeneration apparatus of the prior art. The structure and connection of the regeneration device used here are as follows:
the other ends of the catalyst regeneration inclined tube and the catalyst regeneration inclined tube are respectively connected with a catalytic regeneration settling section and a regeneration section of the regeneration device, and the regeneration settling section of the regeneration device is positioned at the upper part of the regeneration section. The spent catalyst in the reaction section enters the reducing section from the lower part of a bed layer of the reaction section, is subjected to gas stripping by nitrogen or other gases which do not influence the dehydrogenation reaction of the raw material, and enters the regeneration section through a spent inclined tube.
An external circulating pipe is arranged between the regeneration settling section and the catalyst regeneration section, one end of the external circulating pipe is connected with the lower side part of the catalyst regeneration section, and the other end of the external circulating pipe is connected with the lower side part of the regeneration settling section.
The regeneration inclined tube is provided with a section of vertical tube at a position close to the regeneration settling section, and the vertical tube is a pipeline parallel to the axial direction of the regeneration settling section. A chevron baffle is disposed within the riser.
Other arrangements in the settling section and the regenerative settling section of the reactor are consistent with the present invention.
The results are shown in Table 1:
TABLE 1 distribution of propane dehydrogenation product with a content of 99% by weight and propene selectivity, wt.%
Figure BDA0001261614580000121
The effects of the invention and the comparative examples are shown in Table 1. Compared with the comparison scheme, the propylene single-pass yield is 1.34 percent higher than that of the comparison scheme, the propylene selectivity is 3.75 percent higher, and the improvement effect is obvious.
Example 3:
preparing isobutene by dehydrogenating isobutane by adopting the equipment in the embodiment 1 of the invention
Raw materials: 98 wt% of isobutane, with a feed rate of 0.5t/h
Catalyst: environment-friendly metal oxide catalyst ADHO-1(ZL 201110123675.1)
Reaction conditions are as follows: arranging a layer of grating every 0.5m on the catalyst bed layer in the reaction section; bed average temperature, 580 ℃; settler pressure, 0.025 MPa; when the quality is empty, 3 h; the average linear velocity of gas at the outlet section of a riser of the reaction section is 0.45 m/s; the average linear velocity of the gas at the cross section where the bottom of the settling section of the reactor is connected with the reactor is 1.8 m/s.
Regeneration conditions are as follows: a layer of grating can be arranged in the dense-phase section of the regenerator every 0.5 m; regenerator dense phase temperature, 700 ℃.
The structure form of the anti-repeating system is as follows: the invention is provided; in contrast, patent application CN 201611042006.0.
The reaction-regeneration apparatus of patent application CN 201611042006.0 was identical to that described in example 2.
TABLE 2 Isobutane dehydrogenation product distribution and isobutene selectivity, wt%, at 98 wt%
Figure BDA0001261614580000131
The effects of the present invention and the effects of the comparative examples are shown in Table 2. Compared with the comparison scheme, the single-pass yield of the isobutene is 3.82 percentage points higher than that of the comparison scheme, the selectivity of the isobutene is 3.69 percentage points higher, and the isobutene selectivity improving effect is very obvious.

Claims (18)

1. The application of a reaction device in catalytic dehydrogenation reaction of alkane comprises a reaction section and a reactor settling section, wherein the reactor settling section is positioned at the upper part of the reaction section, the cross section of the reaction section is circular, and the diameter of the cross section of the reaction section is gradually reduced from bottom to top;
the reaction device also comprises a catalyst regeneration inclined tube and a feeding distributor, wherein the catalyst regeneration inclined tube extends into the reaction section, and the feeding distributor is positioned below the outlet end of the catalyst regeneration inclined tube in the reaction section;
the whole catalyst lifting pipe is arranged in the reaction section, the outlet end of the catalyst regeneration inclined pipe in the reaction section is connected with the catalyst lifting pipe,
wherein, the feeding distributor is an annular pipe, a nozzle is arranged on the annular pipe, and the catalyst lifting pipe and the reaction section are coaxially arranged.
2. The use according to claim 1, wherein the outlet end of the catalyst regeneration chute is connected to the side wall of the catalyst riser.
3. The use according to claim 2, wherein the outlet end of the catalyst riser inside the reaction section is located in the lower part of the reaction section.
4. The use according to any one of claims 1 to 3, wherein a pre-riser is further provided in the catalyst riser, and the outlet end of the pre-riser is located above the upper edge of the outlet end of the catalyst regeneration inclined tube.
5. The use according to any one of claims 1 to 3, characterized in that a pre-riser is arranged in the catalyst riser, and the outlet end of the pre-riser is higher than the upper edge of the outlet end of the catalyst regeneration inclined tube by a distance of not more than 0.1m in the axial direction.
6. The use of any one of claims 1 to 3, wherein a pre-riser is further arranged in the catalyst riser, and the outlet end of the pre-riser is positioned at the same horizontal plane with the upper edge of the outlet end of the catalyst regeneration inclined tube.
7. The use according to claim 4, characterized in that the outlet of the pre-riser is at a position on the central axis of the catalyst riser.
8. The use of claim 3, wherein the catalyst regeneration chute is connected to the catalyst riser at a distance of from 0.1m to 2.0m from the upper edge of the outlet end of the catalyst regeneration chute to the outlet of the catalyst riser.
9. The use of claim 3, wherein the catalyst regeneration chute is connected to the catalyst riser at a distance of from 0.3m to 1.0m from the upper edge of the outlet end of the catalyst regeneration chute to the outlet of the catalyst riser.
10. A preparation method of olefin by alkane dehydrogenation comprises the following steps that raw materials enter a reaction section from a feeding distributor, the raw materials and a catalyst flow upwards in a parallel flow mode and contact with each other to carry out catalytic reaction, wherein the lower ends of the reaction section and a settling section of a reactor are positioned at the cross section of the same horizontal plane, the average linear velocity of gas is controlled to be 0.3-10.0 m/s, the reaction temperature is controlled to be 500-650 ℃, the mass space time of the reaction is 0.1-15 hours,
the reaction device for preparing the olefin by dehydrogenating the alkane comprises a reaction section and a reactor settling section, wherein the reactor settling section is positioned at the upper part of the reaction section, the cross section of the reaction section is circular, and the diameter of the cross section of the reaction section is gradually reduced from bottom to top;
the reaction device also comprises a catalyst regeneration inclined tube and a feeding distributor, wherein the catalyst regeneration inclined tube extends into the reaction section, and the feeding distributor is positioned below the outlet end of the catalyst regeneration inclined tube in the reaction section;
the whole catalyst lifting pipe is arranged in the reaction section, the outlet end of the catalyst regeneration inclined pipe in the reaction section is connected with the catalyst lifting pipe,
wherein, the feeding distributor is an annular pipe, a nozzle is arranged on the annular pipe, and the catalyst lifting pipe and the reaction section are coaxially arranged.
11. The method according to claim 10, wherein the reaction temperature is controlled to 550 to 620 ℃.
12. The preparation method according to claim 10, wherein the mass space time of the reaction is 1-8 h.
13. The process according to claim 10, wherein the average linear velocity of the gas at the outlet cross section of the catalyst riser in the reaction zone is controlled to be 0.01 to 3 m/s.
14. The method according to claim 10 or 13, wherein the superficial gas velocity in the riser is 0.5 to 20 m/s.
15. The preparation method according to claim 10 or 13, wherein the linear velocity of the lifting medium at the outlet of the pre-lift pipe is controlled to be 5-50 m/s.
16. The process of claim 10, wherein the average linear velocity of the gas at the outlet cross section of the catalyst riser in the reaction zone is controlled to be 0.2 to 0.7 m/s.
17. The method according to claim 10 or 13, wherein the superficial gas velocity in the riser is 3 to 10 m/s.
18. The preparation method according to claim 10 or 13, characterized in that the linear velocity of the lifting medium at the outlet of the pre-lift pipe is controlled to be 15-30 m/s.
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