KR101651751B1 - Dehydogenation reactor - Google Patents

Abstract

The present invention relates to a dehydrogenation reactor for conducting a catalytic hydrocarbon process wherein the reactor of the annular housing is surrounded by a catalyst bed in which the central region is fixed by inner and outer screens. The central region and the radial catalyst bed are surrounded by an annular region that accommodates the heat exchange means.

Description

[0001] DEHYDOGENATION REACTOR [0002]

The present invention relates to a dehydrogenation reactor useful for the dehydrogenation of various hydrocarbon feedstocks, and more particularly to a dehydrogenation reactor comprising a cyclic reaction zone comprising a catalyst bed with a vertical space in a long reactor housing.

The dehydrogenation reaction, such as dehydrogenation of propane with propylene and isobutane with isobutene, produces olefins which are more reactive than alkane feedstocks and which are easier to form coke, at relatively high temperatures used for dehydrogenation. Coke formation on the catalyst causes catalyst deactivation and decreases product yield. Coke formation in the reactor or downstream device can lead to increased reactor pressure and clogging causing reactions such as additional coke formation and methane formation, again reducing useful product yield and causing shutdown of the apparatus for coke removal.

The dehydrogenation reaction is highly endothermic and requires a large amount of heat transfer to the catalyst bed. A shorter residence time is desirable to prevent the olefin product from reacting further to produce coke, but in conventional systems, an increase in olefin production rate increases the endothermic burden of the reactor, lowering the temperature much faster and lowering the product yield, Which requires a shorter cycle time or additional interstage heating, which is not practical.

The dehydrogenation reactor is a very large, long columnar vertical structure with a diameter of about 5 to 30 feet and a length of 10 to 100 feet or more. The general structure of such a reactor can be injected into the inlet located at the bottom center of the vertical reactor, where the gas flows through the annular zone and passes radially outward through a porous catalyst bed or other suitable dehydrogenation catalyst Passes upwardly through the outer annular zone to be discharged at the top of the outer periphery of the reactor. These reactors are often referred to as "radial" reactors because the reactant gas flow through the catalyst bed is radial.

Also, because of the flow characteristics across the extended vertical length of the reactor, longitudinal or axial flow converts to radial or transverse flow and then back to vertical flow, this reactor also has a flow rate through the catalyst bed from top to bottom Is widely varied in a conventional reaction vessel, so that the catalyst life is reduced in the region of the reactor having the highest flow rate. The slowest feed rate through the catalyst bed in the radial reactor generally occurs near the top of the reactor and the fastest rate through the catalyst bed occurs near the reactor bottom near the feed pipe, as evidenced by experiment and flow measurements. This increased speed at the top of the catalyst bed and the reduced rate at the top of the catalyst bed greatly shortens the life of the catalyst near the bottom of the reactor and is much earlier than usual expected to pause the reactor for catalyst regeneration.

U.S. Patent No. 6,472,577 discloses a dehydrogenation reactor comprising a catalyst bed, wherein the interior of the reactor is divided into upper and lower portions as shown in Fig. 1, but in the existing dehydrogenation reactor disclosed in this patent, And a path leading to the outer wall of the reactor through the disc-shaped catalyst layer. This causes a large deviation in the flow velocity between the upper and lower portions of the reactor, thereby restricting the utilization of the catalyst layer smoothly. Also, since the reactor space is used as a discharge channel after the reaction, the product is exposed at a high temperature and the process unit intensity is increased due to the bulk reaction.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the prior art described above and to minimize the flow velocity difference between the upper and lower portions of the reactor to keep the velocity of the fluid passing through the reactor constant, It is intended to extend the service life.

Another object of the present invention is to minimize the variation of the flow rate in the upper and lower parts of the catalyst layer, the inner layer and the outer layer by utilizing the gas dispersion technique in both the inlet and the outlet of the dehydrogenation reactor, And to maximize efficiency.

Another object of the present invention is to isolate the lower portion of the reactor from the reaction space to minimize an increase in process unit load due to the bulk reaction.

According to one aspect of the present invention for achieving the above object,

A catalyst inlet, a reactor inlet for supplying a fluid reactant to the inside of the reactor, a reactor radially surrounding the center of the reactor, and a concentrator 1. A dehydrogenation reactor comprising a cyclic reaction zone defined by an inner and outer screen of a catalyst bed on a catalyst bed and a reactor outlet for withdrawing a reactant stream from within the reactor,

And an annular gas distribution plate disposed between the catalyst inlet and the annular region for dispersing a reaction gas introduced into the reactor inlet,

Characterized in that a central gas flow passage is formed in the center of the reactor, the reactor inlet is formed at one side of the upper end of the reactor, and the reactor outlet is formed in the same side of the reactor as the reactor inlet. Lt; / RTI >

The dehydrogenation reactor of the present invention has a structure in which a reaction flow passes through an inner dispersion plate at an upper end of a reactor, passes through a catalyst layer and goes to a lower portion of a final reactor. In the reactor, a gas is dispersed by a differentiated outlet gas distributor, And the gas is dispersed in a scallops structure.

In addition, in the upper part of the reactor of the present invention, a catalyst heat treatment part is designed in the form of a ring disk to efficiently control the temperature at the time of raising the catalyst temperature, isolate the lower part of the reactor from the reaction space, purging the space with hydrogen gas, Recirculate.

According to the dehydrogenation reactor of the present invention, the flow velocity difference between the upper and lower portions of the reactor is minimized, and the gas dispersion technique is utilized for both the inlet and the outlet of the reactor to minimize the variation of the flow velocity in the upper and lower parts This makes it possible to maximize the performance of the reactor by making it possible to utilize the catalyst layer evenly.

In addition, the dehydrogenation reactor of the present invention can improve the productivity by minimizing the process unit load increase by bulk reaction by isolating the lower portion of the reactor from the reaction space.

1 is a schematic cross-sectional view of a conventional dehydrogenation reactor.
2 is a schematic cross-sectional view of a dehydrogenation reactor according to an embodiment of the present invention.
3 is a schematic perspective view of a cylindrical gas distribution plate of a dehydrogenation reactor according to an embodiment of the present invention.
4 is a schematic perspective view of a lateral disperser of a dehydrogenation reactor according to an embodiment of the present invention.
5 is a schematic perspective view of an annular disc type heat treatment unit of a dehydrogenation reactor according to an embodiment of the present invention.

The present invention will now be described in more detail with reference to the accompanying drawings.

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped. Like reference numerals refer to like elements throughout the specification.

Although the drawings illustrate specific shapes of the dehydrogenation reactor of the present invention, such a dehydrogenation reactor may have various shapes suitable for the specific environment in which it is performed in a particular application, And the like. Moreover, the numbers in the figures represent a simple schematic diagram of the dehydrogenation reactor of the present invention, only major components being shown. Other pumps, moving pipes, valves, hatches, access outlets, and other similar components have been omitted. The use of these components to modify the described dehydrogenation reactor is well known to those skilled in the art and does not depart from the scope and spirit of the appended claims.

As used herein, the term "fluid" means a gas, liquid, or gas or liquid containing a dispersed solid or a mixture thereof. The fluid may be in the form of a gas containing dispersed droplets.

As used herein, the term "reaction zone" means the space in the dehydrogenation reactor where the reactants are in contact with the catalyst on the catalyst bed.

The term "screen" in the context of the present invention has a broad meaning, including means suitable for limiting the catalyst to the catalyst bed while allowing flow of the reactant stream across the catalyst bed. Many such screens are known and it is desirable to design such internal and external catalyst holding screens to reduce catalyst wear because the catalyst particles that descend through the annular catalyst bed are somewhat weak. Alternatively, the screens may comprise punch plates, perforated plates or perforated pipes. The size of the pores should be such that the flow of reactants through the screen is facilitated, while the passage of the catalyst particles is inhibited. The holes of the perforated plate may be in the form of a circle, a square, a rectangle, a triangle, a narrow horizontal or vertical slot, or the like. The screens used in the present invention are not limited to cylindrical screens. Furthermore, the screens comprise a group of planar plates interconnected to form a catalyst particle retaining structure, such as a cylinder.

2 is a schematic diagram of a dehydrogenation reactor 100 according to the present invention. Referring to FIG. 2, the dehydrogenation reactor 100 according to an embodiment of the present invention includes a housing 20 forming the inside of a dehydrogenation reactor, a reactor inlet 21 for supplying a fluid reactant into the reactor, An annular reaction zone (25) enclosing the catalyst bed of the catalyst particles (11) and containing a concentric catalyst bed and defined by an inner screen (23) and an outer screen (24) A dehydrogenation reactor comprising a reactor outlet (26) for withdrawing a reactant stream, characterized in that the reactor inlet (21) is provided between the catalyst inlet (10) and the annular zone (25) A central gas flow passage (60) capable of flowing gas is formed in the center of the reactor, and the reactor inlet (21) Is formed on the top side of the reactor group, the reactor outlet 26 are formed on the same side of the reactor and the reactor inlet.

According to the dehydrogenation reactor (100) of the present invention, the deviation of the catalyst flow velocity in the upper part and the lower part of the reactor can be minimized, and the catalyst can be used evenly to prolong the lifetime of the catalyst and improve the reaction efficiency.

The dehydrogenation reactor of one embodiment of the present invention comprises a catalyst particle capable of being transported as an annular bed through a dehydrogenation reactor by a gravity stream and a dehydrogenation reactor for contacting the reactant stream with a radial stream.

Referring to FIG. 2, the dehydrogenation reactor 100 is constituted by an outer cylindrical housing 20, and the annular reaction zone 25 including the catalyst bed accommodated therein is spaced radially at a certain distance from each other, Is separated by a flow passage (50).

The upper portion of the reaction region of the housing 20 includes a catalyst inlet portion 10 located above the annular reaction region 25 and connected to the space around the catalyst bed in an open state. This catalyst inlet 10 supplies the catalyst to the catalyst bed in the annular reaction zone. The catalyst particles 11 pass through at least one inlet passage 12 that opens into the upper portion of the housing 20 from the catalyst inlet 10 at the upper end of the housing 20 and the annular reaction in the upper portion of the housing 20 Is introduced into the catalyst bed of the zone 25 and the catalyst is exhausted through the plurality of catalyst outlet pipes 27 located in the lower part of the catalyst bed in the annular reaction zone 25. [

The inner and outer screens 23 and 24 formed on the inner and outer sides of the catalyst bed are large enough to allow the fluid flow stream to pass through without any flow resistance or a large pressure drop so that the accommodated catalyst particles 11 can not pass through, And is composed of a screen or a porous body having a mesh size that is sufficiently small.

The reactor feed comprising the hydrocarbon to be treated at a suitable temperature and pressure in the dehydrogenation reactor of the present invention is introduced via the reactor inlet 21 and the annular gas distribution plate 30 ), And then fed to the annular reaction zone 25 containing the catalyst bed of the dehydrogenation reactor 100. The reactant passes through the catalyst bed and is finally discharged to the reactant outlet 26 formed on the lower side of the reactor.

A cylindrical gas dispersion plate is installed on the upper part of the dehydrogenation reactor of the present invention.

3 is a schematic perspective view of a cylindrical gas distribution plate 30 of a dehydrogenation reactor according to an embodiment of the present invention. The cylindrical gas distribution plate 30 is a donut-shaped structure including a hollow portion 32 connected to the central fluid flow passage 60 at the center thereof. A nozzle 31 is disposed on one side of the cylindrical gas dispersion plate , The nozzle 31 is provided so as to communicate with the reactor inlet 21 on the side of the cylindrical gas distributor plate 30. The cylindrical gas distribution plate 30 is provided with a plurality of vent holes 33 for passing gas therethrough.

Reactant gas is supplied through the reactant supply passages 50 between the central fluid flow passage 50 and the inner screen 23 through the vent holes of the cylindrical gas distribution plate. Thus, the reactant gas can be injected into the reactant supply passages in the middle of the reactor so that the reactant gases can be dispersed in a uniform manner throughout the annular reaction zone 25. [

However, in the dehydrogenation reactor of the present invention, after passing through the cylindrical gas dispersion plate 30 and the reactant supply passage 50 inside the reactor, the catalyst layer 25 to the outlet gas distributor 40 of a differentiated scallops structure.

Referring to FIG. 4, in the dehydrogenation reactor of the present invention, a plurality of outlet gas distributors 40 are connected to the outer side of the outer screen 24 in the circumferential direction to diffuse gas in all directions. As an example, the outlet gas distributor 40 may be a vertical cylinder comprising orifices that diffuse the gas into the interior space.

A plurality of perforations 41 of the outlet gas distributor 40 are formed in the longitudinal direction. In addition, the outlet gas distributor 40 may be formed in a tubular shape. The upper half of the upper portion of the reactor is smaller in cross-sectional area than the lower portion of the upper portion and increases in cross- sectional area from the upper surface to the interface between the upper half portion and the lower half portion. . There may also be a plurality of outlet gas distributors 40 in the circumferential direction and there may be exit gas dispersion period gas passages, in this case interconnected to mitigate the problem of gas dispersion due to differential pressure between the outlet gas distributors . There are several holes in the outlet channel of the outlet gas distributor. The size is a factor designed for optimal fluid dispersion according to the size of the product. The number and position of the outlet are designed in various directions such as a rhombic array, a rectangular array and a square array . In the case of a surface which is in contact with an external screen, an external screen may serve as a substitute for the contact surface of the gas distribution plate, depending on the situation.

In the dehydrogenation reactor of the present invention, a gas dispersion plate may be installed outside the catalyst bed to uniformly supply the reactant to the catalyst bed.

In addition, in order to control the temperature efficiently when the catalyst temperature rises, a ring-shaped disk-shaped heat treatment section 13 is provided on the upper part of the reactor in the reaction.

5 is a schematic perspective view of an annular disc type heat treatment unit of a dehydrogenation reactor according to an embodiment of the present invention.

In the heat treatment section 13, the reactant is heated or cooled to a suitable temperature by contact with the heat treatment section 13 including the screen after the hot reducing gas enters the injection port 14, and the heat transfer medium Enters the reactor through the gas outlet 15, passes through the annular reaction zone 25, and is discharged through the reactant outlet 26.

In general, the heating and cooling means of the present invention comprise an annular disk-shaped heat treatment section 13 including a screen disposed relative to at least one catalyst bed, and may optionally be provided with a radial inlet or outlet flow The gaseous process stream can be heated or cooled. In one embodiment, the heat exchange apparatus may be disposed in the reactor core region inside the annular portion of the innermost catalyst bed on a single catalyst bed or a series of radially spaced concentric annular catalyst beds.

A lower space 70 is formed at the lower end of the reactor 100 to separate purge gas from the reaction space for recirculating the purge gas to the outlet through the central gas flow passage. In the dehydrogenation reactor of the present invention, since the lower space 70 is isolated from the reaction space, the product can be prevented from being exposed to a high temperature, thereby preventing an increase in the process unit intensity due to the bulk reaction. The lower space 70 may be purged with hydrogen gas and recycled to the upper portion of the reactor to prevent gas loss.

The dehydrogenation reactor 20 may further include a purge gas injection nozzle 22 installed on an outer circumferential surface of the dehydrogenation reactor 20 for injecting purge gas into the central gas flow passage 60. The hot reducing purge gas is injected through the injection nozzle 22 and is deflected by the deflection plate 28 at the top of the reactor through the cylindrical passageway 60 and fed to the catalyst bed 25.

The lower space 70 of the dehydrogenation reactor 100 may be a collection or collection / heating (or cooling) region in which the reactant stream flows axially toward the reactor outlet 26 and the reactant stream is passed through the reactor outlet 26 Leaving the dehydrogenation reactor 100 and being sent downstream for further processing. As mentioned above, it is also within the scope of the present invention to recover the reactant stream from the bottom of the dehydrogenation reactor 100 or to recover it from the central region.

The dehydrogenation reaction in the dehydrogenation reactor of the present invention will be described below. As shown in FIG. 2, the hydrocarbon reactant will be radially passed through the catalyst bed 25 to dehydrogenate the hydrocarbon to the desired end product.

The reactants introduced through the reactor inlet 21 are heated to a suitable temperature in the central region in contact with the heat exchanger and are dehydrogenated from the hydrocarbons to the desired final product by passing radially through the catalyst bed 25 through the inner wall. The reactant stream radially emerging from the catalyst bed 25 through the outer screen 24 is sent directly through the outer screen 24 to the annular region where it is the collecting region or the reheating or cooling region or both.

While the invention has been described in connection with various specific embodiments, it is to be understood that various modifications thereof will become apparent to those of ordinary skill in the art upon reading the specification. Accordingly, the invention as described herein is intended to embrace such modifications as fall within the scope of the appended claims.

100: dehydrogenation reactor 10: catalyst inlet
20: reactor housing 21: reactant inlet
22: purge gas inlet 23: inner screen
24: outer screen 25: catalyst bed
30: annular gas distribution plate 40: side disperser
50: reactant supply passage 60: central gas flow passage
27: catalyst outlet pipe 26: reactor outlet
70: Lower space

Claims (6)

A catalyst inlet, a reactor inlet for supplying a fluid reactant to the inside of the reactor, a reactor radially surrounding the center of the reactor, and a concentrator 1. A dehydrogenation reactor comprising a cyclic reaction zone defined by an inner and outer screen of a catalyst bed on a catalyst bed and a reactor outlet for withdrawing a reactant stream from within the reactor,
And a annular gas distribution plate disposed between the catalyst inlet and the annular reaction zone for dispersing a reaction gas flowing into the reactor inlet,
A center gas flow passage through which gas can flow is formed in the center of the reactor, the reactor inlet is formed at one side of the upper end of the reactor, the reactor outlet is formed in the same reactor side as the reactor inlet,
Wherein the lower space of the reactor is formed with a lower space separated from a reaction space connected to the central gas flow passage.
The dehydrogenation reactor according to claim 1, wherein a gas dispersion plate is provided outside the catalyst bed to uniformly supply the reactant to the catalyst bed.
The dehydrogenation reactor according to claim 1, wherein a ring-shaped disk-shaped heat treatment unit is provided at an upper portion of the reactor to efficiently control the temperature when the temperature of the catalyst is raised.
delete The dehydrogenation reactor according to claim 1, wherein the central gas flow passage is configured to increase the cross-sectional diameter toward the lower end of the reactor.
The dehydrogenation reactor according to claim 1, wherein a purge gas inlet for injecting a purge gas into the lower space is formed at a lower side surface of the reactor.

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