A riser reactor for recycling heavy aromatics into mixed aromatics

Abstract

The present invention relates to a riser reactor for recycling heavy aromatics in mixed aromatics, which comprises a riser reaction zone, a settler and a regenerator. The riser reaction zone includes a pre-lift section, a cracking reaction section, a diameter-expanding section and an introduction section that are connected in series from bottom to top. The lower part of the pre-lift section is also connected with an enlarged section, in which a fluidization ring, a pre-lift steam nozzle, a pre-lift steam pipe and a lead-out pipe are arranged. The regenerated riser is arranged on the side wall of the enlarged section, and a raw material inlet is provided on the side wall of the pre-lift section. The outlet of the introduction section is connected to a rough cyclone, and the gas-phase outlet of the rough cyclone is connected to the inlet of the first cyclone separator in the settler. There is a stripping zone at the lower part of the settler, and the lower end of the stripping zone communicates with the regenerator. A spent catalyst riser is arranged on the side wall of the regenerator, an air inlet pipe is also arranged on the side wall of the regenerator, a second cyclone separator is arranged above the regenerator, and a lower plug valve is arranged below the regenerator. The present invention has beneficial effects such as improving the catalytic cracking ability of heavy aromatics and increasing the yield of mixed aromatics.

Description

Technical Field

[0001] The present invention relates to a riser reactor, and in particular to a riser reactor for recycling heavy aromatics in mixed aromatics, belonging to the technical field of petrochemical industry. Background Art

[0002] The riser reactor is a core device in a fluid catalytic cracking unit. This device is a vertical tubular reactor with a length of about 40 meters and a diameter of about 0.5 meters to 1.0 meters. During the production process, the feedstock oil is continuously fed into the interior of the tubular reactor, where cracking reactions occur under the conditions of a high temperature of 500°C and a catalyst. In terms of its internal functions, the catalytic cracking riser reactor generally consists of four parts: a bottom pre-lift section, a middle cracking reaction section for feedstock contact and mixing, an upper reaction termination section, and a terminal gas-solid rapid separation section. The feedstock oil is atomized and reacts within about 3 seconds at an average flow rate of about 10 - 15 meters per second. Research results show that the reaction results of catalytic cracking directly depend on the structure and design parameters of the riser reactor.

[0003] Mixed Aromatics is a mixture of aromatic hydrocarbons, containing low molecular weight organic compounds such as C5 - C9, as well as some other impurities: sulfur, benzene, olefins, non-aromatics, etc. Low-density mixed aromatics can be used for gasoline blending, and can also be used for extraction and dilution of pesticides, paints and other chemical products; high-density mixed aromatics (heavy aromatics) are important raw materials for chemical products such as petroleum resins and solvent oils, and can also be used to blend diesel. Hydrotreated high-density mixed aromatics (i.e., heavy aromatics) can also be used to blend gasoline, but the cost is relatively high. With the high demand for downstream products, the global demand for mixed aromatics has been increasing year by year. As the emerging process production capacity of domestic mixed aromatics continues to increase, the industry competition is also becoming increasingly fierce. It is imperative to improve the output value of mixed aromatics. Summary of the Invention

[0004] The present invention mainly aims at the problem of low yield during the catalytic cracking of mixed aromatics by the existing riser reactor, and provides a riser reactor for recycling heavy aromatics in mixed aromatics, which can improve the catalytic cracking ability of heavy aromatics and increase the yield of mixed aromatics.

[0005] The object of the present invention is mainly achieved through the following solutions:

[0006] A riser reactor for recycling heavy aromatics in mixed aromatics, comprising a riser reaction zone, a settler and a regenerator. The riser reaction zone includes a pre-lift section, a cracking reaction section, a diameter-expanding section and an introduction section that are connected through from bottom to top. The lower part of the pre-lift section is also connected with an enlarged section. A fluidization ring, a pre-lift steam nozzle, a pre-lift steam pipe and an extraction pipe are arranged in the enlarged section. The pre-lift steam pipe is arranged in the extraction pipe, the upper part of the pre-lift steam pipe is provided with the pre-lift steam nozzle, and the fluidization ring is arranged below the pre-lift steam nozzle. The regenerator inclined pipe is arranged on the side wall of the enlarged section. A raw material inlet is arranged on the side wall above the pre-lift section. The introduction section is connected with the lower part of the diameter-expanding section through a reflux pipe, and a reflux slide valve is arranged on the reflux pipe. The outlet of the introduction section is connected with a rough cyclone in the settler. The gas phase outlet of the rough cyclone is connected with the inlet of the first cyclone separator in the settler. A stripping zone is arranged at the lower part of the settler, and a stripper is arranged in the stripping zone. The lower end of the stripping zone is communicated with the regenerator through a spent catalyst pipe. A spent catalyst inclined pipe is arranged on the side wall at the lower part of the regenerator and is connected with the regenerator inclined pipe. An air inlet pipe is also arranged on the side wall of the regenerator. A second cyclone separator is arranged above the interior of the regenerator, and a lower plug valve used in cooperation with the spent catalyst pipe is arranged below the interior of the regenerator. The catalyst entering the enlarged section has sufficient buffer space, which can not only reduce the pressure fluctuation of the regenerator inclined pipe discharging materials, but also eliminate the action of its horizontal force, thereby eliminating the uneven flow caused by the S-shaped movement track. The fluidizing steam is beneficial to the distribution of the catalyst to the center of the riser reactor. The heavy aromatics and the catalyst are uniformly mixed and reacted to improve the yield of the target product. The diameter-expanding section can increase the catalyst-oil ratio of this section.

[0007] Preferably, the regenerator inclined pipe and the spent catalyst inclined pipe are connected through a single-acting slide valve to prevent steam from flowing into the regenerator mutually.

[0008] Preferably, the gas phase outlet of the first cyclone separator is connected with a gas collecting chamber, and the gas collecting chamber is externally connected with an oil-gas separation pipeline for separating the products after the catalytic cracking of heavy aromatics.

[0009] Preferably, the diameter of the diameter-expanding section is 2-3 times that of the cracking reaction section. The diameters of the pre-lift section, the cracking reaction section and the introduction section are equal. The diameter of the enlarged section is larger than that of the pre-lift section and smaller than that of the diameter-expanding section.

[0010] Preferably, a flue gas outlet is communicated with the top of the regenerator to facilitate the discharge of the flue gas of the regenerator after the spent catalyst is regenerated.

[0011] Preferably, the regenerator and the settler are coaxially arranged, and the regenerator is located below the settler.

[0012] Preferably, the gas medium of the stripper in the settler is water vapor.

[0013] Preferably, there are 1 - 3 raw material inlets, and multiple raw material inlets can be set according to actual conditions. The raw material inlets are evenly distributed along the axis of the pre-lifting section.

[0014] Therefore, the present invention has the following advantages: (1) The catalyst in the enlarged section has sufficient buffer space, which can not only reduce the pressure fluctuation of the catalyst discharging from the regeneration dipleg, but also eliminate the action of its horizontal force, thus eliminating the uneven flow caused by the S-shaped movement trajectory; (2) The fluidizing steam ejected from the fluidizing ring flows upward through the annular gap formed by the pre-lifting steam pipe and the lead-out pipe, and further supplies steam to the side wall of the riser reaction zone, which is beneficial to the distribution of the catalyst towards the center of the riser reaction zone, and the raw oil and the catalyst are evenly mixed and reacted, improving the yield of the target product; (3) The reaction zone with an enlarged diameter is adopted, which not only retains the relatively high reaction temperature and catalyst-oil ratio at the bottom of the conventional riser reactor to increase the primary cracking reaction, while suppressing the over-cracking and thermal cracking reactions at the top, but also extends the reaction time at a relatively low reaction temperature in the upper and middle parts of the reactor; (4) The introduction section is connected to the lower part of the enlarged section through the reflux pipe. After the oil and gas enter the enlarged section, they contact the supplementary catalyst passing through the reflux pipe and controlled by the reflux slide valve, increasing the reaction catalyst-oil ratio and improving the catalytic cracking effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of the present invention;

[0016] Figure 2 is a schematic structural diagram of the enlarged section of the present invention.

[0017] Illustration: 1 - riser reaction zone, 2 - settler, 3 - regenerator, 4 - pre-lifting section, 5 - cracking reaction section, 6 - enlarged diameter section, 7 - introduction section, 8 - enlarged section, 9 - fluidizing ring, 10 - pre-lifting steam nozzle, 11 - pre-lifting steam pipe, 12 - lead-out pipe, 13 - regeneration dipleg, 14 - pre-lifting section, 15 - cyclone, 16 - first cyclone separator, 17 - stripping zone, 18 - stripper, 19 - spent catalyst pipe, 20 - spent catalyst dipleg, 21 - air inlet pipe, 22 - second cyclone separator, 23 - lower plug valve, 24 - single-acting slide valve, 25 - gas collection chamber, 26 - oil and gas separation pipeline, 27 - flue gas outlet, 28 - reflux pipe, 29 - reflux slide valve. DETAILED DESCRIPTION OF THE INVENTION

[0018] The technical solutions of the present invention will be further specifically described below through examples in combination with the drawings.

[0019] Such as Figure 1 、 2As shown in the figure, the present invention provides a technical solution, a riser reactor for recycling heavy aromatics in mixed aromatics, which is composed of a riser reaction zone 1, a settler 2 and a regenerator 3. The riser reaction zone 1 is composed of a pre-lift section 4, a cracking reaction section 5, a diameter-expanding section 6 and an introduction section 7 which are connected through from bottom to top. A enlarged section 8 is also connected to the lower part of the pre-lift section 4. A fluidization ring 9, a pre-lift steam nozzle 10, a pre-lift steam pipe 11 and a lead-out pipe 12 are arranged in the enlarged section 8. The pre-lift steam pipe 11 is arranged in the lead-out pipe 12. The pre-lift steam nozzle 10 is arranged on the upper part of the pre-lift steam pipe 11. The fluidization ring 9 is arranged below the pre-lift steam nozzle 10. A regenerated slant pipe 13 is arranged on the side wall of the enlarged section 8. A raw material inlet 14 is arranged on the side wall above the pre-lift section 4. The introduction section 7 is connected to the lower part of the diameter-expanding section 6 through a reflux pipe 28. A reflux slide valve 29 is arranged on the reflux pipe 28. The diameter of the diameter-expanding section 6 is twice that of the cracking reaction section 5. The diameters of the pre-lift section 4, the cracking reaction section 5 and the introduction section 7 are equal. The diameter of the enlarged section 8 is larger than that of the pre-lift section 4 and smaller than that of the diameter-expanding section 6.

[0020] The outlet of the introduction section 7 is connected to a rough cyclone 15 in the settler 1. The gas phase outlet of the rough cyclone 15 is connected to the inlet of the first cyclone separator 16 in the settler 2. A gas collecting chamber 25 is connected to the gas phase outlet of the first cyclone separator 16. The gas collecting chamber 25 is externally connected to an oil-gas separation pipeline 26. A stripping zone 17 is arranged at the lower part of the settler 2. A stripper 18 is arranged in the stripping zone 17. The gas medium of the stripper 18 in the settler 2 is water vapor. The lower end of the stripping zone 17 is communicated with the regenerator 3 through a spent catalyst pipe 19. The regenerator 3 and the settler 2 are coaxially arranged. A spent catalyst slant pipe 20 is arranged on the lower side wall of the regenerator 3 and is connected to the regenerated slant pipe 13 through a single-acting slide valve 24. An air inlet pipe 21 is also arranged on the side wall of the regenerator 3. A second cyclone separator 22 is arranged above the interior of the regenerator 3. A lower plug valve 23 which is used in cooperation with the spent catalyst pipe 19 is arranged below the interior of the regenerator 3. A flue gas outlet 27 is communicated with the top of the regenerator 3.

[0021] The reaction process of implementing the riser reactor for recycling heavy aromatics in mixed aromatics of the present invention is as follows: The high-temperature novel petroleum catalyst R-MGOO-MF / B flows from the regenerator 3 into the enlarged section 8 through the spent catalyst slant pipe 20 and the regenerated slant pipe 13, and forms a fluidized state under the action of the fluidization ring 9 at the bottom. The fluidized steam flowing out of the fluidization ring 9 keeps the catalyst at the bottom of the enlarged section 8 in a dense-phase fluidized state. The high-speed steam flow ejected from the pre-lift steam nozzle 10, its jet adsorption effect carries and mixes the surrounding catalyst to form 65 kg / m 3A high-speed catalyst flow with a certain concentration forms a high-speed catalyst flow bundle under the lifting action of pre-lifting steam. It flows through the outlet pipe 12, shoots into the cracking reaction section 5, and is fully mixed with the heavy aromatics sprayed from the raw material inlet 14. Then, it undergoes a catalytic cracking reaction in a high-temperature environment of 525 - 545°C. To enhance the upgrading effect, a catalyst reflux pipe 28 is provided on the inlet section 7 and the diameter-expanding section 6. Part of the catalyst is drawn from the inlet section above the low-temperature reaction zone and returned into the diameter-expanding section 8 to increase the catalyst-to-oil ratio therein. The reaction oil gas and the circulating catalyst enter the rough cyclone 15 and the first cyclone separator 16 in the settler 2 through the inlet section 7. The catalyst is separated from the oil gas and enters the stripping zone 17. The catalyst flows from the spent catalyst pipe 19 to the regenerator 3 and is regenerated through the regenerating medium air. The regenerated catalyst flows into the enlarged section 8 through the spent catalyst inclined pipe 20 and the regenerated catalyst inclined pipe 13 for circulation. The flue gas generated during the regeneration process is discharged through the flue gas outlet 27.

[0022] It is obtained through experiments that when the catalyst-to-oil ratio is 5, the reaction time is 3 s, and the cracking reaction temperatures are 525°C, 535°C, and 545°C respectively, the proportions of the cracked mixed aromatics with a final boiling point of 190°C are 19.15%, 19.26%, and 20.04% respectively. The mixed aromatics contain aromatic components with higher added values, and the proportions are 5.79%, 5.88%, and 6.33% respectively, which can provide raw materials for the downstream aromatics extraction unit. Moreover, by using the new petroleum catalyst R-MGOO-MF / B catalyst, the cracking ability of heavy aromatics is improved, the coke yield is reduced, and finally the output of the product mixed aromatics is increased. When preparing the mixed aromatics by the present invention, the proportion of the cracked mixed aromatics with a final boiling point of 190°C can reach more than 20.04%, and the proportion of the aromatic components with higher added values in the mixed aromatics reaches more than 6.33%.

[0023] It should be understood that the settler, regenerator, fluidization ring, rough cyclone, cyclone separator, stripper, lower plug valve, and slide valve in this embodiment are all components of the prior art or known to those skilled in the art. Their structures and principles can all be known by those skilled in the art through technical manuals or obtained through conventional experimental methods. In addition, it should be understood that this embodiment is only used to illustrate the present invention and not to limit the scope of the present invention. After reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A riser reactor for recycling heavy aromatics in mixed aromatics, characterized in that: The riser reactor includes a riser reaction zone (1), a settler (2), and a regenerator (3). The riser reaction zone (1) includes a pre-lift section (4), a cracking reaction section (5), a diameter-expanding section (6), and an introduction section (7) that are connected through from bottom to top. The lower part of the pre-lift section (4) is also connected with an enlarged section (8). A fluidization ring (9), a pre-lift steam nozzle (10), a pre-lift steam pipe (11), and a draw-off pipe (12) are arranged in the enlarged section (8). The pre-lift steam pipe (11) is arranged in the draw-off pipe (12), the pre-lift steam nozzle (10) is arranged at the upper part of the pre-lift steam pipe (11), the fluidization ring (9) is arranged at the lower part of the pre-lift steam nozzle (10), and a regenerator return pipe (13) is arranged on the side wall of the enlarged section (8). A raw material inlet (14) is arranged on the side wall above the pre-lift section (4). The introduction section (7) is connected with the lower part of the diameter-expanding section (6) through a return pipe (28), and a return slide valve (29) is arranged on the return pipe (28); the outlet of the introduction section (7) is connected with a rough cyclone (15) in the settler (2), and the gas phase outlet of the rough cyclone (15) is connected with the inlet of a first cyclone separator (16) in the settler (2). A stripping zone (17) is arranged at the lower part of the settler (2), and a stripper (18) is arranged in the stripping zone (17). The lower end of the stripping zone (17) communicates with the regenerator (3) through a spent catalyst pipe (19); a spent catalyst return pipe (20) is arranged on the side wall at the lower part of the regenerator (3) and is connected with the regenerator return pipe (13). An air inlet pipe (21) is also arranged on the side wall of the regenerator (3). A second cyclone separator (22) is arranged above the interior of the regenerator (3), and a lower plug valve (23) used in cooperation with the spent catalyst pipe (19) is arranged below the interior of the regenerator (3); the diameter of the enlarged section (8) is larger than the diameter of the pre-lift section (4).

2. The riser reactor for recycling heavy aromatics into mixed aromatics according to claim 1, wherein: The regenerator return pipe (13) and the spent catalyst return pipe (20) are connected through a single-acting slide valve (24).

3. The riser reactor for recycling heavy aromatics into mixed aromatics according to claim 1, wherein: The gas phase outlet of the first cyclone separator (16) is connected with a gas collection chamber (25), and the gas collection chamber (25) is externally connected with an oil-gas separation pipeline (26).

4. The riser reactor for recycling heavy aromatics into mixed aromatics according to claim 1, characterized in that: The diameter of the diameter-expanding section (6) is 2-3 times the diameter of the cracking reaction section (5).

5. The riser reactor for recycling heavy aromatics in mixed aromatics according to claim 4, wherein: The diameters of the pre-lift section (4), the cracking reaction section (5), and the introduction section (7) are equal.

6. The riser reactor for recycling heavy aromatics into mixed aromatics according to claim 1, characterized in that: A flue gas outlet (27) is communicated with the top of the regenerator (3).

7. The riser reactor for recycling heavy aromatics in mixed aromatics according to claim 6, characterized in that: The regenerator (3) is coaxially arranged with the settler (2), and the regenerator (3) is located below the settler (2).

8. A riser reactor for recycling heavy aromatics in mixed aromatics according to claim 7, characterized in that: The gas medium of the stripper (18) in the settler (2) is steam.

9. A riser reactor for recycling heavy aromatics in mixed aromatics according to claim 1, characterized in that: There are 1-3 raw material inlets (14).

10. A riser reactor for recycling heavy aromatics in mixed aromatics according to claim 1, characterized in that: The diameter of the enlarged section (8) is smaller than the diameter of the diameter-expanding section (6).

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