CN100349647C - Multi-segment insulation fix bed reactor - Google Patents

Abstract

The invention relates to a multi-stage adiabatic fixed-bed reactor, which mainly solves the defect of poor gas mixing function of inter-stage tubular feed distributors in the current industrial multi-stage adiabatic fixed-bed reactor. The present invention adopts reactor built-in catalyst bed and inter-section gas mixing device, wherein the inter-section gas mixing device mainly consists of the inlet 9 of the first material, the reactor cylinder 4, the inlet 6 of the second material, the cone 10, and the direct Pipe 11, lateral annulus 12 and sieve plate 13 are composed, which better solves this problem. The reactor has the advantages of simple structure, small pressure drop, rapid and uniform mixing of two streams of materials and uniform distribution of materials, and can be used in the industrial production of ethylbenzene by gas-phase alkylation of benzene and ethylene molecular sieves.

Description

Multi-stage adiabatic fixed bed reactor

Technical field

The invention relates to a multi-stage adiabatic fixed-bed reactor. Specifically, it relates to a multi-stage adiabatic fixed-bed reactor used for gas-phase alkylation of benzene and ethylene molecular sieves to produce ethylbenzene.

Background technique

The multi-stage adiabatic fixed-bed reactor has the characteristics of simple structure, convenient operation, and adaptability to large-scale system production, so it has been widely used in petrochemical industry. For a multi-stage adiabatic fixed-bed reactor, a part of the reaction material is added between the two stages of the catalyst in the reactor. At this time, there are problems of uniform mixing with the material in the previous stage and uniform distribution of the mixed material. The requirement for interstage mixing is to achieve rapid mixing and uniform distribution of the two reaction materials within a limited time and space, so that the materials entering the catalyst bed of the next stage can achieve uniform concentration, uniform temperature and uniform speed along the radial direction.

Ethylbenzene is an important chemical raw material, mainly used for dehydrogenation to produce styrene. In the reaction process of the alkylation of benzene and ethylene to produce ethylbenzene, the reaction rate of the alkylation is mainly controlled by the ethylene concentration, the higher the ethylene concentration is, the faster the reaction rate is, the adiabatic temperature rise of the catalyst bed is increased, and the coking speed is accelerated. Catalyst life shortens and by-products increase. In order to reduce the concentration of ethylene entering the catalyst bed, a multi-stage adiabatic fixed-bed reactor fed from the side line was selected. However, if the material (second gas) entering the reactor from the side line is unevenly mixed with the main material (first gas) in the reactor, the concentration is too high, the reaction speed is fast and the heat is released too much, which is not good for the catalyst; and the concentration is too low , the reaction rate is low, the catalyst is not fully utilized, and the efficiency of the catalyst is reduced. Therefore, the inter-stage mixing effect of the multi-stage adiabatic fixed-bed reactor determines the advantages and disadvantages of the reactor design.

Chinese patent CN2218599Y discloses a feed distributor in a gas-solid phase multi-stage chilled fixed-bed reactor, which is an inter-stage feed pipe distributor commonly used in industrial multi-stage adiabatic fixed-bed reactors. The distributor includes a circular main pipe and branch pipes, and each branch pipe is arranged at an equal angle or at equal intervals in the same section of the reactor. There are 1 to 2 rows of upward and downward small holes on each branch pipe, and the small holes are evenly distributed along the length of the pipe. . However, the distributor requires that the main material in the upper layer must be evenly distributed in order to ensure that the two strands of material are evenly mixed. Such conditions are not always satisfied in industrial installations. Chinese patent CN1030284C discloses a gas-gas mixing device, which is characterized in that strong main body diffusion and turbulent diffusion are generated by the impact of jet flow and perforated plate, so as to realize rapid mixing of gas-gas materials. Although this device can effectively carry out the uniform mixing of the two stocks of materials, it cannot ensure the uniform distribution of the mixed materials.

Contents of Invention

The technical problem to be solved by the present invention is the problem existing in the prior art that two streams of materials are not evenly mixed or distributed between the stages of a multi-stage adiabatic fixed-bed reactor, which affects the utilization rate, selectivity and conversion rate of the catalyst, and provides a New for multi-stage adiabatic fixed bed reactors. The multi-stage adiabatic fixed-bed reactor has the advantages that the main material (first gas) in the reactor and the material (second gas) entering the reactor from the side line are uniformly mixed and the mixed material is evenly distributed into the catalyst bed layer of the next stage.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is as follows: a multi-stage adiabatic fixed-bed reactor, comprising a reactor inlet 3, a reactor cylinder 4, and a reactor outlet 8, and 2 to 10 reactor cylinders are arranged Catalyst bed 5, interstage gas mixing device 7 is arranged between catalyst bed 5, wherein each interstage gas mixing device 7 comprises first kind of material inlet 9, second kind of material inlet 6, reactor cylinder 4, reactor Built-in inverted cone 10, straight pipe 11, lateral annular gap 12 and sieve plate 13, the first material inlet 9 and the second material inlet 6 are respectively located above the inverted cone 10, the upper end of the straight pipe 11 and the inverted cone The lower end of the body 10 is connected, the lower end of the straight pipe 11 forms a lateral annulus 12 with the middle of the sieve plate 13, and is fixed by vertical tie bars. The ratio of the diameter _d1 of the straight pipe 11 to the diameter D of the reactor is 10% to 40%. The angle α between the cone 10 and the horizontal position is 15-75°, the ratio of the diameter d2 of the sieve plate ₁₃ to the diameter D of the reactor is 10-45%, and the opening ratio of the sieve plate 13 is 0-75%. The ratio of the opening area of the plate 13 to the area of the lateral annulus 12 is 0-35%, and the reactor cylinder 4, the straight pipe 11 and the sieve plate 13 have concentric axes.

In the above technical solution, there are two second material inlets 6 in each interstage gas mixing device 7, and the preferred solution is that the inlet directions of the two second material inlets 6 are parallel to the tangent direction of the circle, and the center is symmetrical, and the two The horizontal distance l between the second material inlets 6 is 50-95% of the reactor diameter D, and the preferred range is 70-90%; the ratio of the diameter d of the straight pipe ₁₁ to the reactor diameter D is preferably 15-30 %; the preferred range of the angle α between the inverted cone 10 and the horizontal position is 30-60°; the preferred range of the ratio of the diameter d ₂ of the sieve plate 13 to the reactor diameter D is 15-35%; the opening ratio of the sieve plate 13 The preferred range is 15-50%; the preferred range of the ratio of the opening area of the sieve plate 13 to the area of the lateral annulus 12 is 10-30%.

In the present invention, an adiabatic fixed-bed reactor with a catalyst bed of six stages is taken as an example. The six-stage adiabatic fixed-bed reactor is the main equipment for gas-phase alkylation of benzene and ethylene molecular sieves to produce ethylbenzene. It consists of the first gas inlet pipe 3 , a reactor cylinder 4, a catalyst bed 5, a second gas inlet pipe 6, an interstage gas mixing device 7, and a gas outlet pipe 8, etc., see accompanying drawing 1.

For the six-stage adiabatic fixed-bed reactor for producing ethylbenzene by gas-phase alkylation of benzene and ethylene molecular sieve, an inter-stage gas mixing device is proposed, as shown in accompanying drawings 2 and 3. This type of novel gas mixing device consists of an inlet 9 for the first material, a reactor cylinder 4, an inlet 6 for the second material, an inverted cone 10, a straight pipe 11, a lateral annular gap 12 and a sieve plate 13. In order to ensure that the gas mixing device has a relatively ideal gas mixing effect, it is necessary to control the distance between the two material inlets and the angle α between the cone and the horizontal position, the vertical or horizontal distance between the two side line material inlets 6, and the straight pipe 11 at the center of the lower part. diameter, the opening ratio of the sieve plate 13, and the ratio of the opening area of the sieve plate 13 to the area of the lateral annulus 12. In this way, the two gases can be mixed evenly in the cylinder 4 and the inverted cone 10, and flow into the lower catalyst bed from the sieve plate 13 and the lateral annulus 12 in an appropriate proportion, forming a relatively uniform catalyst bed in the lower catalyst bed. gas distribution.

In the six-stage adiabatic fixed-bed reactor, benzene and ethylene undergo alkylation reaction in the catalyst bed to produce ethylbenzene. The reactor is composed of six catalyst beds connected in series, and benzene and ethylene enter each catalyst bed sequentially. The ethylene introduced from the outside is divided into 6 strands, one of which merges with the main flow of benzene, and the merged stream 1 enters the reactor from the inlet 3 at the top of the reactor. The remaining 5 shares of ethylene are respectively merged with the corresponding emergency cooling benzene stream, and then the 5 (ethylene + quenching benzene) streams 2 enter their respective inter-stage spaces, and merge with the reactor materials from the upstream, and enter the next catalyst bed together, and finally The product leaves the reactor through the bottom gas outlet.

The inter-stage gas mixing device of the present invention has been investigated through a large-scale fixed bed cold model test, and the results show that it has the following advantages: simple structure, convenient installation; good flow equalization effect, which can make the inter-stage gas mixing of multi-stage fixed bed reactors uniform and smooth The ideal gas distribution effect is achieved, and a good technical effect has been achieved.

Description of drawings

Fig. 1 is the multistage adiabatic fixed-bed reactor schematic diagram of the present invention;

Fig. 2 is the structural diagram of the interstage gas mixing device of the multistage adiabatic fixed bed reactor of the present invention;

Fig. 3 is a top view structural diagram of the interstage gas mixing device of the multistage adiabatic fixed bed reactor of the present invention;

In Fig. 1, 1 is the first material; 2 is the second material; 3 is the first material inlet pipe; 4 is the reactor cylinder; 5 is the catalyst bed; 6 is the second material inlet pipe; 7 is an inter-stage gas mixing device; 8 is a gas outlet pipeline.

In Fig. 2, 9 is the inlet of the first material; 4 is the reactor cylinder; 6 is the inlet of the second material; 10 is the inverted cone; 11 is the straight pipe; 12 is the lateral annulus; 13 is the screen plate. D is the diameter of the reactor, d ₁ is the diameter of the straight pipe, d ₂ is the diameter of the sieve plate, Φ is the diameter of the sieve hole on the sieve plate, h ₁ is the height of the straight pipe, h ₂ is the diameter of the lateral annulus channel Height, α is the angle between the cone and the horizontal position. The opening rate of the sieve plate is the ratio of the opening area of the sieve plate to the area of the sieve plate.

In Fig. 3, 4 is the reactor cylinder; 6 is the entrance of the second material; 13 is the sieve plate, and l is the horizontal distance between the two second material inlet pipes.

Below by embodiment the present invention will be further elaborated.

Detailed ways

【Example 1】

Adopt inter-stage gas mixing device as shown in Figure 1, reactor diameter D=600 mm, diameter d ₁ of straight pipe=140 mm, diameter d ₂ of sieve plate=160 mm, diameter of sieve hole on sieve plate Φ=6 mm, the height of the straight pipe h ₁ =100 mm, the height of the lateral annulus channel h ₂ =65 mm, the horizontal distance between the two second material inlet pipes l=450 mm, the angle α between the cone and the horizontal position = 45 °, the ratio of the horizontal distance of the two second material inlets to the diameter of the reactor is 75%, the ratio of the diameter of the straight pipe to the diameter of the reactor is 23.3%, the ratio of the diameter of the sieve plate to the diameter of the reactor is 26.7%, The ratio of the opening area of the sieve plate to the area of the lateral annulus is 18.5%, and the opening ratio of the sieve plate is 26.3%.

Under the above conditions and structural parameters, the inter-stage gas mixing device can be designed according to the method of the present invention, and a relatively ideal gas flow effect can be obtained.

[Example 2]

Adopt interstage gas mixing device as shown in Figure 1, reactor diameter D=1000 mm, diameter d ₁ of straight pipe=168 mm, diameter d ₂ of sieve plate=168 mm, diameter of sieve hole on sieve plate Φ=8 mm, the height h ₁ of the straight pipe = 160 mm, the height h ₂ = 75 mm of the lateral annulus channel, the horizontal distance l = 850 mm between the two second material inlet pipes, the angle α between the cone and the horizontal position = 60 °, the ratio of the horizontal distance of the two second material inlets to the diameter of the reactor is 85%, the ratio of the diameter of the straight pipe to the diameter of the reactor is 16.8%, the ratio of the diameter of the sieve plate to the diameter of the reactor is 16.8%, The ratio of the opening area of the sieve plate to the area of the lateral annulus is 25.3%, and the opening ratio of the sieve plate is 45.1%.

Under the above conditions and structural parameters, the inter-stage gas mixing device can be designed according to the method of the present invention, and a relatively ideal gas flow effect can be obtained.

[Example 3]

Adopt inter-stage gas mixing device as shown in Figure 1, reactor diameter D=600 mm, diameter d ₁ of straight pipe=165 mm, diameter d ₂ of sieve plate=165 mm, diameter of sieve hole on sieve plate Φ=6 mm, the height of the straight pipe h ₁ =120 mm, the height of the lateral annulus channel h ₂ =60 mm, the horizontal distance between the two second material inlet pipes l=420 mm, the angle α between the cone and the horizontal position = 30°, the ratio of the horizontal distance of the two second material inlets to the diameter of the reactor is 70%, the ratio of the diameter of the straight pipe to the diameter of the reactor is 27.5%, the ratio of the diameter of the sieve plate to the diameter of the reactor is 27.5%, The ratio of the opening area of the sieve plate to the area of the lateral annulus is 12.6%, and the opening ratio of the sieve plate is 18.4%.

Under the above conditions and structural parameters, the inter-stage gas mixing device can be designed according to the method of the present invention, and a relatively ideal gas flow effect can be obtained.

[Comparative Example 1]

The conditions and structural parameters of the six-stage adiabatic fixed-bed reactor for producing ethylbenzene by gas-phase alkylation of certain benzene and ethylene molecular sieves are the same as those in Example 1, the only difference being that a tubular gas distributor is used between the stages. Through simulation calculation, according to the method of the present invention, the two stocks of materials are mixed, and the maximum deviation of the uniformity of the same section in the catalyst bed of the lower section is less than 4.0%, and the uniformity of the same section in the catalyst bed of the lower section is less than 4.0%. The maximum deviation was 7.2%.

【Comparative example 2】

The interstage gas mixing device of the six-stage adiabatic fixed-bed reactor of the gas-phase alkylation of benzene and ethylene molecular sieve to produce ethylbenzene in Example 2 was changed to a simple tubular gas distributor, and all conditions were the same as those in Example 2. The maximum deviation of the uniformity of the same section in the lower catalyst bed of Example 2 is less than 4.6%, and the maximum deviation of the uniformity of the same section of this comparative example is 8.8%.

[Comparative Example 3]

The interstage gas mixing device of the six-stage adiabatic fixed-bed reactor of the gas-phase alkylation of benzene and ethylene molecular sieve to produce ethylbenzene in Example 3 was changed to a simple tubular gas distributor, and all conditions were the same as those in Example 2. The maximum deviation of the uniformity of the same section in the lower catalyst bed of Example 3 is less than 4.3%, and the maximum deviation of the uniformity of the same section of this comparative example is 8.0%.

Claims (9)

1, a kind of multistage insulation fixed bed reactor, comprise reactor inlet (3), reactor shell (4), reactor outlet (8), be provided with 2～10 beds (5) in the reactor shell, intersegmental gas mixing apparatus (7) is set between beds (5), wherein each intersegmental gas mixing apparatus (7) comprises first kind of material inlet (9), reactor shell (4), second kind of material inlet (6), the built-in back taper body of reactor (10), straight tube (11), side direction annular space (12) and sieve plate (13), first kind of material inlet (9) and second kind of material inlet (6) lay respectively at the top of back taper body (10), the upper end of straight tube (11) links to each other with the lower end of back taper body (10), form side direction annular space (12) in the middle of the lower end of straight tube (11) and the sieve plate (13), and fix straight tube (11) diameter d by vertical lacing wire ₁With the ratio of reactor diameter D be 10～40%, the angle α of back taper body (10) and horizontal level is 15～75 °, the diameter d of sieve plate (13) ₂With the ratio of reactor diameter D be 10～45%, the percent opening of sieve plate (13) is 0～75%, the area ratio of the perforated area of sieve plate (13) and side direction annular space (12) is 0～35%, reactor shell (4), straight tube (11) and sieve plate (13) have concentric shafts.

2,, it is characterized in that second kind of material inlet (6) has two in each intersegmental gas mixing apparatus (7) according to the described multistage insulation fixed bed reactor of claim 1.

3, according to the described multistage insulation fixed bed reactor of claim 2, the Way in that it is characterized in that above-mentioned two second kind material inlet (6) is parallel to round tangential direction, and the center symmetry, the horizontal range 1 between two second kind material inlet (6) is 50～95% of reactor diameter D.

4,, it is characterized in that the horizontal range 1 between two second kind material inlet (6) is 70～90% of reactor diameter D according to the described multistage insulation fixed bed reactor of claim 3.

5,, it is characterized in that straight tube (11) diameter d according to the described multistage insulation fixed bed reactor of claim 1 ₁With the ratio of reactor diameter D be 15～30%.

6,, it is characterized in that the back taper body (10) and the angle α of horizontal level are 30～60 ° according to the described multistage insulation fixed bed reactor of claim 5.

7,, it is characterized in that the back taper body (10) and the angle α of horizontal level are 30～60 ° according to the described multistage insulation fixed bed reactor of claim 1.

8, according to the described multistage insulation fixed bed reactor of claim 1, the percent opening that it is characterized in that sieve plate (13) is 15～50%.

9,, it is characterized in that the perforated area of sieve plate (13) and the area ratio of side direction annular space (12) are 10～30% according to the described multistage insulation fixed bed reactor of claim 1.

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