Alkylation reactor and reaction method thereof

Abstract

The present invention discloses an alkylation reactor and a reaction method thereof. The reactor includes a shell, wherein a hydrocarbon reactant inlet is provided at the bottom of the shell, and a hydrocarbon reactant outlet is provided at the top. The interior of the shell has an HF circulation conveying area, a mixed reaction area, a centrifugal separation area and a gravity separation area which are sequentially connected from bottom to top; wherein a vertical central axis is installed inside the shell, and the bottom end of the central axis is installed in the HF circulation conveying area, and the top end is installed in the centrifugal separation area. The alkylation reactor and the reaction method thereof in the present invention can make HF circulate completely inside the reactor without the need for separate separation and transportation outside the equipment, thereby greatly reducing the HF transportation equipment and pipelines, and also reducing the amount of HF used. Therefore, the construction cost and operation cost of the alkylation reaction system can be greatly reduced, and the potential safety hazards existing in the circulation and transportation process of HF can be reduced.

Description

Technical Field

[0001] The invention relates to the field of chemical equipment, and in particular to an alkylation reactor and a reaction method thereof. Background Art

[0002] In the production process of alkylbenzene, HF, i.e. hydrogen fluoride gas, is usually used as a catalyst for the alkylation reaction, wherein the reactants are benzene and olefins, and the reaction product is alkylbenzene. In the traditional process, the reactants and catalysts are generally first mixed and reacted in a static mixer outside the reactor, then enter the heat exchanger for cooling, and then enter the reactor for full reaction; then, the reaction products and catalysts enter the horizontal separation tank, and gravity is used to separate the polar HF solution and the non-polar hydrocarbon mixture, and the separated HF is transported to the static mixer through an acid pump and can be recycled.

[0003] In the above-mentioned traditional process, the process of HF circulating outside the reactor needs to pass through a series of equipment such as separation tank, acid pump, mixer, heat exchanger, reactor, etc. in sequence. Since HF is a highly corrosive medium with extremely harmful effects, it is easy to cause major safety hazards. Therefore, during its transportation, it has high requirements for the materials and seals of equipment, pipelines, valves, etc., especially for the impellers and seals of pump equipment. This leads to high production costs for the corresponding equipment. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an alkylation reactor and a reaction method thereof.

[0005] According to one aspect of the present invention, an alkylation reactor is provided, comprising a shell, wherein a hydrocarbon reactant inlet is provided at the bottom of the shell, a hydrocarbon reactant outlet is provided at the top, and the interior of the shell comprises an HF circulation conveying zone, a mixed reaction zone, a centrifugal separation zone and a gravity separation zone which are sequentially connected from bottom to top; wherein a vertical central axis is installed inside the shell, the bottom end of the central axis is installed in the HF circulation conveying zone, and the top end is installed in the centrifugal separation zone.

[0006] In some embodiments, the bottom of the shell has a skirt, and the hydrocarbon reactant inlet is arranged on the side wall of the skirt. Thus, the skirt can support the entire reactor, and the skirt is not connected to the upper regions thereof.

[0007] In some embodiments, an HF circulation inlet is provided around the lower end of the HF circulation transport zone, and a circulation pump housing is installed inside the HF circulation transport zone; wherein the bottom end of the central axis is installed inside the circulation pump housing, and a circulation pump driving impeller and a circulation pump driven impeller are installed at the bottom end of the central axis. Thus, hydrocarbon reactants consisting of alkanes, alkenes and benzene can be mixed with HF in the HF circulation transport zone and then enter the mixed reaction zone together.

[0008] In some embodiments, the mixing reaction zone is divided into an inner cylinder located inside and an outer cylinder located outside, and the bottom and top ends of the inner cylinder are connected to the HF circulation transport zone and the centrifugal separation zone, respectively. Thus, the inner cylinder in the mixing reaction zone is used for mixing and reaction, and the outer cylinder is used for returning the HF discharged after the reaction to the HF circulation transport zone.

[0009] In some embodiments, a plurality of vertical cooling heat exchange tubes are installed between the outer cylinder and the inner cylinder, and a cooling water inlet is installed at the lower end of the outer wall of the outer cylinder, and a cooling water outlet is installed at the upper end. Thus, cooling water can be circulated into the outer cylinder through the cooling water inlet and the cooling water outlet, and the HF in the outer cylinder is cooled through the cooling heat exchange tubes.

[0010] In some embodiments, a spiral guide plate is provided inside the centrifugal separation zone, the spiral guide plate is installed on the central axis, and a plurality of guide holes are provided on the side of the centrifugal separation zone; wherein the top end of the central axis is installed inside the centrifugal separation zone. Thus, most of the HF can be separated out through the centrifugal separation zone, and the remaining hydrocarbon mixture and a small portion of the HF mixture enter the gravity separation zone.

[0011] In some embodiments, the bottom end of the central shaft is installed inside the HF circulation and delivery zone through a lower bearing and a lower bearing support, and the top end of the central shaft is installed inside the centrifugal separation zone through an upper bearing and an upper bearing support. Thus, a specific installation position and method of the central shaft is set, and the impeller for stirring is mainly installed thereon.

[0012] In some embodiments, a plurality of agitator assemblies are installed side by side at the portion of the central axis located in the mixing reaction zone, and the agitator assemblies include agitator impellers and agitator baffles. Thus, the hydrocarbon reactants consisting of alkanes, alkenes and benzene and HF as a catalyst can be fully mixed and reacted by the agitation of the plurality of agitator assemblies.

[0013] According to one aspect of the present invention, a reaction method for the alkylation reactor is provided, comprising the following steps:

[0014] 1) introducing hydrocarbon reactants consisting of alkanes, alkenes and benzene into an alkylation reactor from the hydrocarbon reactant inlet, and introducing HF into the alkylation reactor;

[0015] 2) The hydrocarbon reactant passes through the HF circulation transport zone and enters the inner side of the mixed reaction zone together with the HF entering the HF circulation transport zone;

[0016] 3) In the inner side of the mixed reaction zone, the hydrocarbon reactant is mixed with HF, the alkane olefin and benzene react to form alkylbenzene, the alkylbenzene and the excess alkane and benzene form a hydrocarbon mixture, and the hydrocarbon mixture and HF are mixed and enter the centrifugal separation zone;

[0017] 4) In the centrifugal separation zone, most of the HF is discharged to the outside of the centrifugal separation zone by centrifugal flow, and the mixture of the hydrocarbon mixture and a small portion of HF enters the gravity separation zone;

[0018] 5) In the gravity separation zone, HF is separated from the hydrocarbon mixture under the action of gravity.

[0019] 6) The separated hydrocarbon mixture is discharged from the alkylation reactor through the hydrocarbon reactant outlet.

[0020] In some embodiments, the method further comprises the following steps: 7) cooling the HF discharged from the centrifugal separation zone through the mixed reaction zone and flowing to the HF circulation transport zone. Thus, the HF is cooled through the outer cylinder outside the mixed reaction zone and flows back to the HF circulation transport zone, so that the HF can be reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of an alkylation reactor according to one embodiment of the present invention;

[0022] Figure 2 for Figure 1 The structural schematic diagram of the HF circulation transport area shown;

[0023] Figure 3 for Figure 1 A partial structural schematic diagram of the mixing reaction zone shown;

[0024] Figure 4 for Figure 1 Schematic diagram of the partial structure of the centrifugal separation zone shown.

[0025] In the figure: shell 1, hydrocarbon reactant inlet 2, hydrocarbon reactant outlet 3, HF circulation and conveying area 4, mixing reaction area 5, centrifugal separation area 6, gravity separation area 7, central axis 8, agitator assembly 9, skirt 11, HF circulation suction port 41, circulation pump housing 42, circulation pump driving impeller 43, circulation pump driven impeller 44, inner cylinder 51, outer cylinder 52, cooling heat exchange tube 53, cooling water inlet 54, cooling water outlet 55, spiral guide plate 61, guide hole 62, lower bearing 81, lower bearing support 82, upper bearing 83, upper bearing support 84, agitator impeller 91, agitator baffle 92. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0027] Figure 1 The structure of an alkylation reactor according to one embodiment of the present invention is schematically shown. Figure 2 Shows Figure 1 The structure of the HF circulation transport zone in Figure 3 Shows Figure 1 The structure of the mixing reaction zone in Figure 4 Shows Figure 1 The structure of the centrifugal separation zone in Figure 1-4 As shown, the alkylation reactor includes a shell 1, which is generally cylindrical and placed vertically, and each component of the reactor is integrated in the shell 1. The interface type of the reactor and each component thereon can be flange, thread, or welding, etc. as required, and can be made of suitable metal materials or non-metal materials (such as various impellers and guide plates and other rotating structures) as required.

[0028] A hydrocarbon reactant inlet 2 is provided at the bottom of the housing 1, a hydrocarbon reactant outlet 3 is provided at the top, and the interior has an HF circulation conveying zone 4, a mixed reaction zone 5, a centrifugal separation zone 6 and a gravity separation zone 7 from bottom to top. The hydrocarbon reactant inlet 2 is connected to the HF circulation conveying zone 4, the HF circulation conveying zone 4 and the centrifugal separation zone 6 are both connected to the inner side of the mixed reaction zone 5, the centrifugal separation zone 6 is connected to the gravity separation zone 7, and the gravity separation zone 7 is connected to the hydrocarbon reactant outlet 3.

[0029] A vertical central shaft 8 is also installed inside the housing 1. The bottom end of the central shaft 8 is installed in the HF circulation and conveying area 4, and the top end is installed in the centrifugal separation area 6. Various parts of the central shaft 8 are installed with impellers and other structures for stirring.

[0030] Preferably, a skirt 11 is provided at the bottom of the housing 1, and the skirt 11 can support the upper structure of the alkylation reactor. The hydrocarbon reactant inlet 2 is arranged on the side wall of the skirt 11, and the skirt 11 is not connected with the HF circulation transport area 4 and other structures.

[0031] The bottom of the HF circulation conveying area 4 is connected to the hydrocarbon reactant inlet 2, and a plurality of HF circulation suction ports 41 are arranged around the lower end of the HF circulation conveying area 4. The HF circulation suction ports 41 can suck HF (hydrogen fluoride gas) distributed in the alkylation reactor into the HF circulation conveying area 4. A circulation pump housing 42 is installed inside the HF circulation conveying area 4, and the bottom end of the central shaft 8 is installed inside the circulation pump housing 42. A circulation pump driving impeller 43 and a circulation pump driven impeller 44 are fixedly installed at the bottom end of the central shaft 8. When gas is introduced from the hydrocarbon reactant inlet 2 to the HF circulation conveying area 4, the circulation pump driving impeller 43 and the circulation pump driven impeller 44 can be driven to rotate, thereby driving the central shaft 8 to rotate together.

[0032] Preferably, the bottom end of the central shaft 8 is connected to a lower bearing 81, the lower bearing 81 is connected to a lower bearing support 82, and the lower bearing support 82 is installed on the inner wall of the circulating pump housing 42. The lower bearing 81 is composed of a rolling bearing and a thrust bearing, the thrust bearing mainly bears the static load generated by the central shaft 8 and other components fixed on the central shaft 8, and the rolling bearing is used to fix the axial position of the central shaft 8.

[0033] The mixing reaction zone 5 is mainly divided into an inner cylinder 51 and an outer cylinder 52. The inner cylinder 51 is located inside the outer cylinder 52, that is, the inner cylinder 51 is located inside the mixing reaction zone 5, and the outer cylinder 52 is located outside the mixing reaction zone 5, that is, the shell 1 of this part of the reactor. The lower end of the inner cylinder 51 extends and is connected to the HF circulation and conveying zone 4, and the upper end extends and is connected to the centrifugal separation zone 6. The HF circulation inlet 41 is specifically arranged on the lower end of the inner cylinder 51.

[0034] The central axis 8 passes through the inner cylinder 51 of the mixing reaction zone 5. A plurality of agitator assemblies 9 are relatively evenly installed side by side in the middle section of the inner cylinder 51, i.e., between the circulation conveying zone 4 and the centrifugal separation zone 6. Each agitator assembly 9 includes an agitator impeller 91 and an agitator baffle 92, which can fully stir and mix the various substances in the inner cylinder 51.

[0035] A plurality of cooling heat exchange tubes 53 are distributed and installed in the outer cylinder 52 and the inner cylinder 51 of the mixing reaction zone 5. Each cooling heat exchange tube 53 is vertically arranged and spaced a certain distance from each other. A cooling water inlet 54 is installed at the lower end of the outer wall of the outer cylinder 52, and a cooling water outlet 55 is installed at the upper end. Cooling water is introduced from the cooling water inlet 54, and the cooling water flows out from the cooling water outlet 55 after passing through each cooling heat exchange tube 53, so as to cool the HF in the outer cylinder 52.

[0036] The centrifugal separation area 6 mainly includes the upper end of the inner cylinder 51, and the top end of the central axis 8 is installed inside the upper end of the inner cylinder 51 of the centrifugal separation area 6. A spiral guide plate 61 is provided inside the centrifugal separation area 6, that is, inside the upper end of the inner cylinder 51, and the spiral guide plate 61 is fixedly installed on the central axis 8; and a plurality of guide holes 62 are provided on the side of the centrifugal separation area 6, that is, on the side of the upper end of the inner cylinder 51.

[0037] Preferably, the top end of the central shaft 8 is connected to an upper bearing 83, and the upper bearing 83 is connected to an upper bearing support 84, and the upper bearing support 84 is installed on the inner wall of the top end of the central shaft 8. The upper bearing 83 is also composed of a rolling bearing and a thrust bearing, the thrust bearing mainly bears the static load generated by the central shaft 8 and other components fixed on the central shaft 8, and the rolling bearing is used to fix the axial position of the central shaft 8.

[0038] The gravity separation zone 7 is provided with a gravity separation device, which can separate the hydrocarbon reaction products and HF under the action of gravity and form a stable two-phase interface. The gravity separation device can be selected from the prior art according to actual conditions.

[0039] When the alkylation reactor is used for reaction operation, HF is introduced into the alkylation reactor, and hydrocarbon reactants consisting of alkanes and benzene are input into the interior of the alkylation reactor from the hydrocarbon reactant inlet 2, and the hydrocarbon reactants flow from bottom to top successively through the HF circulation and transportation area 4, the mixed reaction area 5, the centrifugal separation area 6, and the gravity separation area 7, and the final reaction product is a hydrocarbon mixture consisting of alkylbenzene, alkanes and benzene, which is discharged from the hydrocarbon reaction product outlet at the top of the reactor. The specific process is as follows.

[0040] The hydrocarbon reactants composed of alkanes, alkenes and benzene first enter the circulating pump housing 42 of the HF circulating and conveying zone 4, and flow from bottom to top inside the circulating pump housing 42, driving the circulating pump driving impeller 43 to rotate, thereby driving the central shaft 8 to rotate, and the circulating pump driven impeller 44 rotates along with the central shaft 8, generating a downward attraction force, sucking the HF in the reactor from the HF circulating suction port 41 into the bottom end of the lower cylinder in the HF circulating and conveying zone 4, while the hydrocarbon reactants are mixed with the sucked HF and enter the mixed reaction zone 5. Among them, the density difference of the fluid between the inner cylinder 51 and the outer cylinder 52 also provides a part of the power for the entry of HF.

[0041] Then, in the middle section of the lower cylinder in the mixing reaction zone 5, the stirrer assembly 9 rotates driven by the central shaft 8, and the hydrocarbon reactants and HF are fully mixed under the action of the stirrer assembly 9. Under the action of the catalyst HF, the alkane olefins and benzene fully react to generate alkylbenzenes, and some excess alkanes and benzene will also appear in the reaction. The alkylbenzenes, the excess alkanes and benzene together constitute a hydrocarbon mixture, and the hydrocarbon mixture and HF are mixed and enter the centrifugal separation zone 6.

[0042] Then, inside the upper end of the lower cylinder in the centrifugal separation zone 6, the spiral guide plate 61 rotates driven by the central shaft 8, and the mixture entering therein forms a centrifugal flow under the action of the spiral guide plate 61. Under the action of centrifugal force, the HF with a higher density accumulates on the inner wall of the inner cylinder 51, and most of the HF is discharged along the guide holes 62 on the side wall of the inner cylinder 51; while the hydrocarbon mixture with a lower density accumulates in the center of the reactor inner cylinder 51, and enters the gravity separation zone 7 along the axial direction from the top of the reactor inner cylinder 51 with a small part of HF.

[0043] Then, in the gravity separation zone 7, a small portion of HF is gradually separated from the hydrocarbon mixture under the action of gravity, and a stable two-phase interface is formed. Finally, the fully separated hydrocarbon mixture is discharged from the reactor through the hydrocarbon reaction product outlet at the top of the reactor.

[0044] Among them, most of the HF discharged from the centrifugal separation area 6 enters between the outer cylinder 52 and the inner cylinder 51 of the mixed reaction area 5, and enters each cooling heat exchange tube 53, and exchanges heat with the cooling water outside the cooling heat exchange tube 53, thereby taking away the heat generated by the reaction process and achieving a cooling effect. The cooled HF can flow to the bottom of the mixed reaction area 5 and be sucked into the HF circulation and transportation area 4 again by the HF circulation suction port 41, thereby achieving recycling. Furthermore, the cooled HF can also exchange heat with the ongoing reaction in the inner cylinder 51, and transfer the reaction heat in time to control the reaction temperature.

[0045] In addition, the power source for the rotation of the central shaft 8 comes from the power generated by the flow of hydrocarbon reactants entering the reactor, and when the flow rate of hydrocarbon reactants entering the reactor decreases, the rotation speed of the central shaft 8 also decreases accordingly, and then the HF circulation amount driven by the shaft circulation pump driven impeller 44 also decreases accordingly. Therefore, by controlling the flow rate and flow rate of the hydrocarbon reactants, it is possible to achieve automatic mixing of the reactants and the catalyst HF in a certain proportion.

[0046] Compared with the conventional alkylation reaction equipment, the alkylation reactor of the present invention has the following advantages:

[0047] 1) It integrates mixing, reaction, separation and catalyst circulation, so that HF ​​can be completely circulated inside the reactor, without the need for separate separation and transportation outside the equipment, thereby greatly reducing the HF transportation equipment and pipelines, and also reducing the amount of HF used. Therefore, it can greatly reduce the construction cost and operation cost of the alkylation reaction system, and reduce the safety hazards existing in the HF circulation and transportation process;

[0048] 2) No external force is required to drive the rotating parts, no mechanical seal is required, the equipment structure is simple, and it is easy to manufacture and install;

[0049] 3) It can automatically achieve equal proportion mixing of catalyst and reactant without the need for additional flow regulation facilities;

[0050] 4) The mechanical energy loss is small. The kinetic energy of high-pressure fluid can be efficiently converted into the kinetic energy of low-pressure fluid, which effectively reduces the mechanical energy loss of HF during the circulation and transportation process and reduces energy consumption;

[0051] 5) The catalyst HF and the reactants are forced to be fully mixed by stirring, and the mixing effect is better than the mixing effect of the static mixer in the traditional system, which is more conducive to improving the reaction efficiency;

[0052] 6) The centrifugal separation of HF and hydrocarbon mixtures has a much better separation effect than the gravity separator in the traditional system, which can greatly reduce the size of the separation equipment, reduce the amount of HF used, reduce the system footprint, and reduce the equipment investment and operation and maintenance costs;

[0053] 7) In addition to being applicable to alkylation reactions, it can also be applied to other types of heterogeneous catalytic reaction systems;

[0054] 8) It has a simple structure and occupies a small area, and is suitable for the transformation of existing devices.

[0055] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. An alkylation reactor, characterized in that: The invention comprises a shell (1), wherein a hydrocarbon reactant inlet (2) is provided at the bottom of the shell (1), and a hydrocarbon reactant outlet (3) is provided at the top. The interior of the shell (1) comprises, from bottom to top, an HF circulation transport zone (4), a mixed reaction zone (5), a centrifugal separation zone (6) and a gravity separation zone (7) which are connected in sequence. A vertical central axis (8) is installed inside the shell (1), wherein the bottom end of the central axis (8) is installed in the HF circulation transport zone (4), and the top end is installed in the centrifugal separation zone (6). An HF circulation suction port (41) is arranged around the lower end of the HF circulation conveying area (4), and a circulation pump housing (42) is installed inside the HF circulation conveying area (4); wherein the bottom end of the central shaft (8) is installed inside the circulation pump housing (42), and a circulation pump driving impeller (43) and a circulation pump driven impeller (44) are installed at the bottom end of the central shaft (8); The mixing reaction zone (5) is divided into an inner cylinder (51) located inside and an outer cylinder (52) located outside, and the bottom end and the top end of the inner cylinder (51) are respectively connected to the HF circulation transport zone (4) and the centrifugal separation zone (6); A plurality of vertical cooling heat exchange tubes (53) are installed between the outer cylinder (52) and the inner cylinder (51); a cooling water inlet (54) is installed at the lower end of the outer wall of the outer cylinder (52), and a cooling water outlet (55) is installed at the upper end; A spiral guide plate (61) is provided inside the centrifugal separation zone (6), and the spiral guide plate (61) is installed on the central axis. A plurality of guide holes (62) are provided on the side of the centrifugal separation zone (6); wherein the top end of the central axis (8) is installed inside the centrifugal separation zone (6).

2. An alkylation reactor according to claim 1, characterized in that: The bottom of the housing (1) is provided with a skirt (11), and the hydrocarbon reactant inlet (2) is arranged on the side wall of the skirt (11).

3. An alkylation reactor according to claim 1, characterized in that: The bottom end of the central shaft (8) is installed inside the HF circulation transport zone (4) via a lower bearing (81) and a lower bearing support (82), and the top end of the central shaft (8) is installed inside the centrifugal separation zone (6) via an upper bearing (83) and an upper bearing support (84).

4. An alkylation reactor according to claim 3, characterized in that: A plurality of agitator assemblies (9) are installed side by side at the portion of the central axis (8) located in the mixing reaction zone (5), and the agitator assemblies (9) include an agitator impeller (91) and an agitator baffle (92).

5. A reaction method for an alkylation reactor according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) introducing hydrocarbon reactants consisting of alkanes, alkenes and benzene into the interior of an alkylation reactor from the hydrocarbon reactant inlet (2), and introducing HF into the alkylation reactor; 2) the hydrocarbon reactant passes through the HF circulation transport zone (4) and enters the inner side of the mixed reaction zone (5) together with the HF entering the HF circulation transport zone (4); 3) In the inner side of the mixing reaction zone (5), the hydrocarbon reactant is mixed with HF, the alkane olefin and benzene react to form alkylbenzene, the alkylbenzene and the excess alkane and benzene form a hydrocarbon mixture, and the hydrocarbon mixture and HF are mixed and enter the centrifugal separation zone (6); 4) In the centrifugal separation zone (6), most of the HF is discharged to the outside of the centrifugal separation zone (6) by centrifugal flow, and the mixture of the hydrocarbon mixture and a small portion of HF enters the gravity separation zone (7); 5) In the gravity separation zone (7), HF is separated from the hydrocarbon mixture under the action of gravity; 6) The separated hydrocarbon mixture is discharged from the alkylation reactor through the hydrocarbon reactant outlet (3).

6. The reaction method according to claim 5, characterized in that: The following steps are also included: 7) The HF discharged from the centrifugal separation zone (6) is cooled via the mixing reaction zone (5) and flows into the HF circulation transfer zone (4).

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