Method for Catalytic Conversion of Hydrocarbon with Downer Reactor and Device Thereof

Abstract

Provided are a method for the catalytic conversion of hydrocarbons with a downer reactor and a device thereof. The specific process of the method is as follows: a raw material of hydrocarbons after being pre-heated (or not) and a low-temperature regenerant from a regenerant cooler entering an entry end of a downer reactor, flowing down along the reactor for reactions such as catalytic cracking, and a mixture of a reactive oil and gas and a catalyst descending to the end of the reactor for rapid separation, thereby achieving the rapid separation of the catalyst and the oil and gas. The main operation conditions thereof are as follows: the reaction temperature is 460 to 680° C., the reaction pressure is 0.11 to 0.4 MPa, the contact time is 0.05 to 2 seconds, and the weight ratio of the catalyst to the raw material (a catalyst-to-oil ratio) is 6 to 50. The separated catalyst to be regenerated (abbreviated as a spent agent) is stripped by means of a stripper, and enters a regenerator and is burned for regeneration, wherein the regeneration temperature is controlled at 630-730° C. The regenerant from the regenerator enters the regenerant cooler to be cooled to 200-720° C., and then enters the downer reactor for recycling

Claims

1.-12. (canceled)

13. A method for catalytic conversion of a hydrocarbon using a downer reactor, wherein a regenerated catalyst from a regenerator, after being cooled by a regenerated catalyst cooler, enters a downer reactor and is mixed and contacted with a hydrocarbon raw material at an inlet end of the downer reactor; the regenerated catalyst and the hydrocarbon raw material go on a catalytic conversion reaction of the hydrocarbon in the downer reactor, and flow co-currently downward to a tail end of the downer reactor for rapid separation; a separated spent catalyst, after being stripped, enters a regenerator and is burned for regeneration to form a regenerated catalyst, and the regenerated catalyst, after being cooled by a regenerated catalyst cooler, is returned and recycled to the downer reactor for reuse; and the regenerated catalyst cooler is used for improving the concentration of the catalyst in the downer reactor.

14. The method according to claim 13, wherein a catalyst mixing and buffering space is arranged downstream of the regenerated catalyst cooler, and the catalyst mixing and buffering space is operated by a low-velocity dense-phase fluidized bed having a superficial gas velocity of less than 0.3 m/s.

15. The method according to claim 13, wherein optimization of a reaction temperature of the downer reactor is achieved by adjusting a temperature of the regenerated catalyst entering the downer reactor.

16. The method according to claim 13, wherein the downer reactor is operated under the following main conditions: a reaction temperature of 460-680° C., a reaction pressure of 0.11-0.4 MPa, a contact time of 0.05-2 seconds, and a catalyst-to-oil ratio of 6-50, and wherein the regenerated catalyst is cooled to a temperature of 200-720° C.

17. The method according to claim 16, wherein the reaction temperature is 480-660° C., the reaction pressure is 0.11-0.4 MPa, the contact time is 0.1-1.5 seconds, and the catalyst-to-oil ratio is 8-40.

18. The method according to claim 17, wherein the reaction temperature is 490-650° C.

19. The method according to claim 1, wherein a specific process of the method is as follows: 1) the hydrocarbon raw material, after being preheated or being not preheated, and the low-temperature regenerated catalyst from the regenerated catalyst cooler enter the inlet end of the downer reactor, and react while flowing downward along the reactor; when a mixture of a reacting oil and gas and the catalyst flows downward to the tail end of the reactor, a rapid separation is performed to realize rapid separation of the catalyst and the oil and gas, wherein the downer reactor is operated under the following main conditions: a reaction temperature of 460-680° C., a reaction pressure of 0.11-0.4 MPa, a contact time of 0.05-2 seconds, and a catalyst-to-oil ratio of 6-50; 2) the separated spent catalyst, after being stripped by a spent catalyst stripper, enters the regenerator and is burned for regeneration, wherein a regeneration temperature is controlled at 630-730° C.; 3) the regenerated catalyst from the regenerator enters the regenerated catalyst cooler and is cooled to 200-720° C., and the cooled regenerated catalyst is recycled to the inlet end of the downer reactor for reuse; or a hot regenerated catalyst bypass is arranged, so that a portion of the hot regenerated catalyst is mixed with the cold regenerated catalyst and then a mixed regenerated catalyst is recycled to the inlet end of the downer reactor for reuse.

20. The method according to claim 19, wherein the temperature of the mixed regenerated catalyst is independently controlled by adjusting proportions of the cold regenerated catalyst and the hot regenerated catalyst; or the temperature of the cold regenerated catalyst is controlled by adjusting a flow rate of a fluidizing medium and/or a flow rate of a heat-removing medium, or by adjusting a flow rate of a fluidizing medium and/or a flow rate of a heat-removing medium and/or a flow rate of the cold catalyst returned to the regenerator.

21. The method according to claim 1, wherein a reaction temperature of the downer reactor is controlled by adjusting a catalyst-to-oil ratio, or/and by adjusting a temperature of a cold regenerated catalyst or a temperature of a mixed regenerated catalyst.

22. The method according to claim 13, wherein the hydrocarbon raw material is any heavy oil having been hydrogenated or having not been hydrogenated, including one of straight-run gas oil, coking gas oil, hydrocracked tail oil, atmospheric pressure residual oil, vacuum residual oil, shale oil, synthetic oil, crude oil, coal tar, recycle oil, oil slurry, deasphalted oil, thermal cracking heavy oil, viscosity-reduced heavy oil, heavy diesel, and the like, or a mixture of two or more than two thereof; the straight-run gas oil fraction or the coking gas oil fraction includes high-density cycloalkyl or naphthenic intermediate gas oil (distillate oil), and is a full-range fraction or a partial narrow fraction thereof; or the hydrocarbon raw material is a light hydrocarbon raw material, which is an olefin-containing hydrocarbon or saturated liquid light hydrocarbon in a refinery or a petrochemical plant, including any one of liquefied petroleum gas, light oil, and the like, or a mixture of more than one thereof in any ratio; the liquid light hydrocarbon is C4 and C5 fractions containing butene and pentene, or a mixture thereof in any ratio; the light oil is a gasoline fraction, including one or two or more than two of straight-run gasoline, gas condensate, catalytic cracking gasoline, thermal cracking gasoline, viscosity-reduced gasoline, coking gasoline, pyrolysis gasoline, or a mixture gasoline thereof in any ratio, and is a full-range gasoline or a partial narrow fraction thereof; or the light oil is a diesel fraction, including catalytic cracking diesel, and is a full-range diesel or a partial narrow fraction thereof.

23. The method according to claim 1, wherein the method is implemented separately, or the downer reactor is coupled to a riser reactor, wherein a gas-solid co-currently flowing folding-type fast fluidized bed reactor or a gas-solid co-current down-flowing and up-flow and down-flow coupled catalytic cracking reactor is used.

24. A device for catalytic conversion of a hydrocarbon using a downer reactor, wherein the device includes the downer reactor, a rapid separation unit, a spent catalyst stripper, a regenerator, a regenerated catalyst cooler, wherein the downer reactor is a gas-solid co-currently flowing folding-type fast fluidized bed reactor or a gas-solid co-current down-flow and up-flow coupled catalytic cracking reactor.

25. The device according to claim 24, wherein a catalyst mixing and buffering space is arranged at the downstream location of the regenerated catalyst cooler.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIGS. 1-3 are typical schematic diagrams of devices for catalytic conversion using a downer reactor according to the present invention.

[0054] The present invention is described in detail below in connection with the accompanying drawings. The drawings are drawn to illustrate the present invention and are not intended to limit any particular implementation of the inventive concept of the present invention.

[0055] FIG. 1 is a block flow diagram of a method for catalytic conversion using a downer reactor according to the present invention.

[0056] As shown in FIG. 1, the method for catalytic conversion of the present invention comprises an inlet end 1 of the downer reactor, the downer reactor 2, a rapid separation unit 3, a spent catalyst stripper 4, a regenerator 5, a regenerated catalyst cooler 6, a catalyst mixing and buffering space 7, and a secondary separator 8.

[0057] A feedstock oil, after being preheated and warmed up, enters a feedstock nozzle. The feedstock oil is atomized under the action of an atomizing steam, at which time the feedstock oil enters, in the form of fine droplets, a mixing section in the downer reactor 2. In the meantime, a high-temperature catalyst coming from the regenerator 5, after being cooled by the regenerated catalyst cooler 6 and then passed through the catalyst mixing and buffering space 7 located at the downstream location (or at a lower portion) to reach temperature equilibrium, enters the inlet end 1 of the downer reactor and then enters the downer reactor 2 and is mixed with the atomized feedstock oil. The gas phase and the solid phase both are rapidly contacted and thoroughly mixed with each other in the mixing section, then flow co-currently downward along the reactor 2 while undergoing a catalytic conversion reaction. When reaction products and the catalyst flow, in a mixed manner, co-currently downward to a tail end of the downer reactor 2, the gas-solid rapid separation unit 3 rapidly separates the catalyst and the product oil and gas, or the product oil and gas is quenched (to avoid a secondary reaction; not shown in the figure) and enters the secondary separator 8 (such as a cyclone separator) for further removal of the catalyst and then enters a downstream fractionation or separation system for further separation to obtain desired gas products and liquid products. The main operating conditions are as follows: a reaction temperature of 460-680° C. (preferably 480-660° C., most preferably 490-630° C.); a reaction pressure of 0.1-0.4 MPa; a contact time of 0.05-2 seconds (preferably 0.1-1.5 seconds); and a weight ratio of the catalyst to the feedstock oil (catalyst-to-oil ratio) of 6-50 (preferably 8-40).

[0058] The separated spent catalyst is stripped by the spent catalyst stripper 4 and then enters the regenerator 5 and is burned for regeneration. The regeneration temperature is controlled at 630-730° C. (preferably 650-730° C.).

[0059] The regenerated catalyst from the regenerator 5 enters the regenerated catalyst cooler 6 and is cooled to 200-720° C. and then directly returned and recycled to the downer reactor 2 for reuse; or the cold regenerated catalyst leaving a lower portion or a bottom of the regenerated catalyst cooler 6, after being passed through the mixing buffering space 7 for mixing and buffering to reach temperature equilibrium, is returned and recycled to the downer reactor 2 for reuse. The fluidizing medium used may be air, a steam, other gases, or a mixture thereof (preferably a steam).

[0060] In order to achieve optimal control of the reaction temperature and optimal control of the reaction depth, the catalyst mixing and buffering space 7 is arranged at the downstream location of the regenerated catalyst cooler 6 to enhance the mixing of the regenerated catalyst so that the regenerated catalyst reaches temperature equilibrium before entering the downer reactor 2, so as to meet requirements of downstream reaction temperature control. In order to save space and investment, the catalyst mixing and buffering space 7 may also be an integrated structure with the regenerated catalyst cooler 6 and having a same diameter as that of the regenerated catalyst cooler 6 (as shown in FIG. 3). The catalyst mixing and buffering space 7 is operated by a low-velocity dense-phase fluidized bed having a superficial gas velocity of less than 0.3 m/s (preferably 0.0001-0.1999 m/s).

[0061] FIG. 2 is a schematic flow chart of a device for catalytic conversion using a downer reactor in a coaxial regeneration mode according to the present invention.

[0062] As shown in FIG. 2, the method for catalytic conversion and the device thereof according to the present invention comprise an inlet end 1 of a downer reactor, the downer reactor 2, a rapid separation unit 3, a spent catalyst stripper 4, a regenerator 5, a regenerated catalyst cooler 6, a catalyst mixing and buffering space 7, a secondary separator 8, and a settler 9.

[0063] The regenerator 5 is connected to the regenerated catalyst cooler 6 through a regenerated catalyst conveying pipe. The regenerated catalyst, after being cooled by the regenerated catalyst cooler 6 and then mixed and buffered in the catalyst mixing and buffering space 7 located at the downstream location (or at a lower portion), is connected to the inlet end 1 of the downer reactor through a cold regenerated catalyst conveying pipe 10. The temperature of the cold regenerated catalyst leaving the regenerated catalyst cooler 6 is controlled by adjusting a flow rate of a fluidizing medium 35 (including air, a steam, etc.). A control valve 21 is a specific control element arranged to facilitate control of the flow rate of the cold regenerated catalyst. The conveying medium 35 may be a steam, or other gases, or a mixture thereof (preferably a steam). A heat-removing medium 37 used may be water, a steam, air or other gases, various oils, or a mixture thereof.

[0064] In order to facilitate control of the temperature of the regenerated catalyst entering the downer reactor, it is also possible to provide a hot regenerated catalyst bypass pipe (including a control valve) (not shown in the figure) directly connected to the catalyst mixing and buffering space 7 in which the cooled regenerated catalyst and the hot regenerated catalyst are thoroughly mixed to reach temperature equilibrium.

[0065] There are of course many other control devices and control methods, and the implementation of the inventive concept of the present invention is not limited in this respect.

[0066] A hydrocarbon raw material and the regenerated catalyst, after being mixed at the inlet end 1 of the reactor, enters the downer reactor 2, and go into a reaction under catalytic conversion conditions. The main operating conditions are as follows: a reaction temperature of 460-680° C. (preferably 480-660° C., most preferably 490-630° C.); a reaction pressure of 0.11-0.4 MPa; a contact time of 0.05-2 seconds (preferably 0.1-1.5 seconds); and a weight ratio of the catalyst to the raw material (catalyst-to-oil ratio) of 6-50 (preferably 8-40).

[0067] When the reaction oil and gas and the catalyst flow, in a mixed manner, co-currently downward to the rapid separation unit 3 at the tail end of the downer reactor 2, the rapid separation unit 3 rapidly separates the catalyst and the product oil or gas; or the high-temperature product oil and gas is quenched (to avoid a secondary reaction; not shown in the figure) and enters the secondary separator 8 (such as a cyclone separator) for further removal of the catalyst, and then enters a downstream fractionation or separation system for further separation, to obtain desired gas products and liquid products.

[0068] The spent catalyst, after being passed through the settler 9 and stripped by the spent catalyst stripper 4, enters the regenerator 5 through a spent catalyst conveying pipe 13 and a control valve (not shown in the figure), and is burned in the presence of a main wind 38 (an oxygen-containing gas, including such as air etc.). The regenerated catalyst is led out from a lower portion of the regenerator 5, enters the regenerated catalyst cooler 6, and then enters the catalyst mixing and buffering space 7 for thorough mixing. After that, the cold regenerated catalyst is recycled for reuse by way of a conveying pipe 11 (or mixed with the hot regenerated catalyst) (it is also possible to provide another catalyst conveying pipe to return the catalyst to the regenerator). (Of course, a separate external heat exchanger may also be arranged depending on process requirements to allow flexible operations under multiple operating conditions).

[0069] The regenerated catalyst from the regenerator 5 enters the regenerated catalyst cooler 6 and is cooled to 200-720° C. The cold regenerated catalyst leaving the lower portion or the bottom of the regenerated catalyst cooler 6 is mixed and buffered in the catalyst mixing and buffering space 7 to reach temperature equilibrium, and then returned and recycled to the inlet end 1 of the downer reactor and the reactor 2 for reuse. The fluidizing medium 39 may be air, a steam, or other gases, or a mixture thereof (preferably a steam).

[0070] In order to achieve precise control and optimal control of the reaction temperature, the catalyst mixing and buffering space 7 is arranged at the downstream location of the regenerated catalyst cooler 6 to enhance the mixing of the regenerated catalyst, so that the regenerated catalyst reaches temperature equilibrium before entering the inlet end 1 of the downer reactor and the reactor 2, so as to meet the requirements of precise downstream reaction temperature control. In order to save space and investment, the catalyst mixing and buffering space 7 may also be designed as a structure in one-piece with the regenerated catalyst cooler 6 and having a same diameter as that of the regenerated catalyst cooler 6. The catalyst mixing and buffering space 7 is operated by a low-velocity dense-phase fluidized bed having a superficial gas velocity of less than 0.3 m/s (preferably 0.0001 0.1999 m/s).

[0071] FIG. 3 is a schematic flow chart of a device for catalytic conversion using a downer reactor in a fast bed regeneration mode according to the present invention.

[0072] As shown in FIG. 3, the method for catalytic conversion and the device thereof according to the present invention comprise an inlet end 1 of the downer reactor, the downer reactor 2, a rapid separation unit 3, a spent catalyst stripper 4, a regenerator 5, a regenerated catalyst cooler 6, a catalyst mixing and buffering space 7, a secondary separator 8, and a settler 9.

[0073] The regenerator 5 is connected to the regenerated catalyst cooler 6 through a regenerated catalyst conveying pipe. The regenerated catalyst, after being cooled by the regenerated catalyst cooler 6 and mixed and buffered in the catalyst mixing and buffering space 7 located at the downstream location (or at a lower portion) to reach temperature equilibrium, is connected to the inlet end 1 of the downer reactor through a cold regenerated catalyst conveying pipe 10. The temperature of the cold regenerated catalyst leaving the regenerated catalyst cooler 6 is controlled by adjusting the flow rate of a fluidized medium 35 (including air, a steam, etc.). A control valve 21 is a specific control element arranged to facilitate control of the flow rate of the cold regenerated catalyst.

[0074] In order to facilitate control of the temperature of the regenerated catalyst entering the downer reactor, it is also possible to provide a hot regenerated catalyst conveying pipe (including a control valve and not shown) directly connected to the regenerated catalyst mixing and buffering space 7 in which the cold regenerated catalyst and the hot regenerated catalyst are mixed to reach temperature equilibrium.

[0075] There are of course many other control devices and control methods, and the implementation of the inventive concept of the present invention is not limited in this respect.

[0076] The catalyst cooler described above may be integrated with the regenerator or the downer reactor or may be connected thereto through pipelines.

[0077] The hydrocarbon raw material and the regenerated catalyst, after being mixed, enter the downer reactor, and go into a reaction under catalytic conversion conditions. The main operating conditions are as follows: a reaction temperature of 460-680° C. (preferably 480-660° C., most preferably 490-630° C.); a reaction pressure of 0.11-0.4 MPa; a contact time of 0.05-2 seconds (preferably 0.1-1.5 seconds); and a weight ratio of the catalyst to the raw material (the catalyst-to-oil ratio) of 6-50 (preferably 8-40).

[0078] The reaction oil and gas and the catalyst flow, in a mixed manner, co-currently down to the rapid separation unit 3 at the tail end of the downer reactor 2. The high temperature oil and gas from the rapid separation unit 3, then enters or after being quenched enters (to avoid a secondary reaction, not shown in the figure), the secondary separator 8 (such as a cyclone separator) for further removal of the catalyst, then a high temperature oil and gas from the secondary separator 8 enters a downstream fractionation or separation system for further separation, or is quenched again (to avoid a secondary reaction, not shown in the figure) and then enters a downstream fractionation or separation system for further separation, to obtain desired gas products and liquid products.

[0079] The separated spent catalyst, after being stripped by the spent catalyst stripper 4, enters a coke burning tank 5A through a spent catalyst conveying pipe 13 and a control valve 20, and is rapidly burned in the presence of a main wind 38A (an oxygen-containing gas, including such as air etc.), and is then sent upward to the regenerator 5 and is further burned for regeneration. The bottom of the regenerator 5 is supplemented with a secondary wind 38B (an oxygen-containing gas, including such as air etc.). The regenerated catalyst is led out from the lower portion of the regenerator 5, and enters the regenerated catalyst cooler 6 and the regenerated catalyst mixing and buffering space 7. The cold regenerated catalyst is recycled for reuse by way of the conveying pipe 11 (or mixed with the hot regenerated catalyst). Another conveying pipe 12 may be arranged (the conveying pipe 12 may not be arranged) to return the catalyst to the regenerator (Of course, a separate external heat exchanger may be arranged depending on process requirements to allow flexible operations under multiple operating conditions).

[0080] The regenerated catalyst from the regenerator 5 enters the regenerated catalyst cooler 6 and is cooled to 200-720° C. The cold regenerated catalyst leaving the lower portion or the bottom of the regenerated catalyst cooler 6 is mixed and buffered in the catalyst mixing and buffering space 7 to reach temperature equilibrium, and then returned and recycled to the inlet end of the downer reactor and the reactor 2 for reuse. The fluidizing medium 39 may be air, a steam, or other gases, or a mixture thereof (preferably a steam). The heat-removing medium 37 may be water, a steam, air or other gases, various oils, or a mixture thereof. The conveying medium 36 may be air, a steam, or other gases, or a mixture thereof.

[0081] In order to achieve precise control and optimal control of the reaction temperature, the mixing buffer space 7 is arranged at the downstream location of the regenerated catalyst cooler to enhance the mixing of the regenerated catalyst, so that the regenerated catalyst reaches temperature equilibrium before entering the downer reactor 2, to meet requirements of downstream reaction temperature control. In order to save space and investment, the catalyst mixing and buffering space 7 and the regenerated catalyst cooler 6 may also be designed as an integrated structure, in which the catalyst mixing and buffering space 7 has a same diameter as that of the regenerated catalyst cooler 6. The catalyst mixing and buffering space 7 is operated by a low-velocity dense-phase fluidized bed having a superficial gas velocity of less than 0.3 m/s (preferably 0.0001-0.1999 m/s).

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0082] Before a further detailed description of the specific embodiments of the present invention, it should be appreciated that the scope of the present invention is not limited to the specific embodiments described below, and that the terms in the embodiments of the present invention are used for the purpose of describing particular embodiments only and are not intended to limit the scope of the present invention.

[0083] It should be appreciated that that, unless otherwise indicated by the present invention, when numerical ranges are given in the embodiments, both endpoints of each numerical range and any numerical value between the two endpoints are optional. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art. The present invention may be implemented using any existing methods, devices, or materials similar to or equivalent to methods, devices, and materials used in the embodiments of the present invention based on the knowledge of those skilled in the art about the existing technologies and the disclosure of the present invention, in addition to the specific methods, devices, and materials used in the embodiments.

Example 1

[0084] In order to verify the effects of the present invention, the process flow shown in FIG. 2 or FIG. 3, a heavy oil raw material having properties shown in Table 1, process conditions of the existing technology and the present invention shown in Table 2, as well as a molecular sieve catalyst (CHP-1) that maximizes propylene production were used. Test results are listed in Table 3.

[0085] The results in Table 3 show that, due to the thermal equilibrium limitation of the existing downer reactor, the existing technology can achieve a catalyst-to-oil ratio of only up to 11.5 at a feed temperature of 230° C., and thus cannot realize the large catalyst-to-oil ratio operation required by a downer reactor. Compared with the existing technology, the present invention decreases the yield of coke and dry gas by 1.8 percentage points, increases the total yield of light oil (LPG+gasoline+diesel) by 2.1 percentage points, increases the total yield of liquids (total yield of light oil+oil slurry) by 1.8 percentage points, and also decreases the yield of diesel by 10 percentage points, and thus realizes a good product distribution. For a set of 1 million tons/year heavy oil catalytic cracking unit, the present invention can bring an annual economic increase of about 90 million RMB.

TABLE-US-00001 TABLE 1 Properties of heavy oil raw material Heavy oil raw material Density, 20/4° C. 0.881 Residual carbon 0.4% (Wt) Sulfur content 0.15% (Wt) 

TABLE-US-00002 TABLE 2 Comparison of process conditions of the existing technology and the present invention Existing Present technology invention Parameters Solution A Solution B reaction temperature, ° C. 560 560 feed temperature, ° C. 230 280 regeneration temperature, ° C. 700 700 temperature of regenerated catalyst 695 648 entering the downer reactor, ° C. catalyst-to-oil ratio, weight/weight 11.5 16.1 reaction time, second 1.1 0.8

TABLE-US-00003 TABLE 3 Products product yield Wt % Existing technology Present invention fuel gas + H.sub.2S 5.1 4.1 LPG 13.1 25.1 gasoline 38.5 39.2 diesel 29.7 19.1 oil slurry 5.3 5.0 coke 8.3 7.5 Total 100.0 100.0 Total yield of light oil 81.3 83.4 Total yield of liquids 86.6 88.4

Example 2

[0086] In Example 2, the raw material for the downer reactor was catalytic cracking gasoline, and the downer reactor needed to adopt an ultra-large catalyst-to-oil ratio of about 30 to optimize the reaction temperature distribution, improve the reaction selectivity, increase the yields of propylene and gasoline, and improve the aromatic content in gasoline and the octane number of gasoline, and reduce the olefins content in gasoline.

[0087] This example adopts the process flow shown in FIG. 2 or FIG. 3, process conditions of the existing technology and the present invention shown in Table 4, as well as a molecular sieve catalyst (CHP-1) that maximizes propylene production. The gasoline raw material and test results are listed in Table 5.

[0088] The results in Table 4 indicate that, due to the thermal equilibrium limitation of the existing downer reactor, solution B of the existing technology realizes a catalyst-to-oil ratio of only 12.1 at a feed temperature of 400° C. under thermal equilibrium. Such a catalyst-to-oil ratio will severely affect the conversion rate and selectivity of the downer reactor. Although solution A can increase the catalyst-to-oil ratio to 25.9 at a feed temperature of 40° C., it will seriously affect the recovery and utilization of the low temperature heat in the device.

[0089] The results in Table 5 show that, compared with the existing technology, the present invention increases the yield of high value-added propylene by 1.2 percentage points, realizes quite a similar yield of coke and dry gas and quite a similar total yield of light oil, decreases the aromatics content in gasoline by 3.7 percentage points, reduces the olefins content by 3 percentage points, and increases the octane number (RON) by 0.8-2 units. Further, Table 4 shows that the present invention can also maximize the recovery efficiency of waste heat due to the use of a high-temperature feed at 400° C.

[0090] All these indicate that the method for catalytic conversion of gasoline according to the present invention produces significant beneficial effects.

TABLE-US-00004 TABLE 4 Properties of gasoline raw material Existing technology Parameters Solution A Solution B Present invention reaction temperature, ° C. 610 610 610 feed temperature, ° C. 400 400 400 regeneration temperature, ° C. 690 690 690 temperature of regenerated 685 685 652 catalyst entering the downer reactor, ° C. Catalyst-to-oil ratio, 25.9 12.1 30 weight/weight reaction time, second 0.6 0.6 0.6

TABLE-US-00005 TABLE 5 Comparison of process conditions of the existing technology and the present invention Products Solution A of Solution B of Properties of existing existing product yield Wt % raw material technology technology dry gas 3.6 3.7 LPG 28.6 31.5 wherein propylene 10.1 11.3 gasoline 64.3 61.5 diesel coke 3.5 3.3 Total 100.0 100.0 Total yield of light oil 92.9 93 (including LPG) Properties of gasoline Group composition: (V %) olefins 43.6 15.8 12.8 aromatic hydrocarbons 8.1 39.6 43.3 alkanes 34.8 31.7 31.1 cycloalkanes 8.2 8.0 7.9 others 5.3 4.9 4.9 Total 100 100 100 octane number (RON) 88.3 90.3 91.1

Example 3

[0091] In Example 3, the raw material for the downer reactor was an olefin-rich mixed C4. This example adopted the process flow shown in FIG. 2 or FIG. 3, and the process conditions of the existing technology and the present invention shown in Table 6, as well as a molecular sieve catalyst ZSM-5.

[0092] A downer reactor usually needs to adopt an ultra-large catalyst-to-oil ratio of over 30 to achieve the purposes of optimizing the reaction temperature distribution, improving the reaction selectivity, and increasing the yield of ethylene and propylene. However, the results in Table 6 indicate that due to the thermal equilibrium limitation of the existing downer reactor, the existing technology realizes a catalyst-to-oil ratio of only 16.3 at a high feed temperature of 400° C. under thermal equilibrium. Such a low catalyst-to-oil ratio will severely affect the conversion rate and selectivity of the downer reactor.

[0093] The mixed C4 raw material used in the present invention and test results are shown in Table 7. Table 7 shows that the yield of high value-added propylene is about 47.2%, and the yield of ethylene is 10.6%, indicating that the method for catalytic conversion of the mixed C4 according to the present invention produces remarkable beneficial effects.

TABLE-US-00006 TABLE 6 Comparison of process conditions of the existing technology and the present invention Parameters Existing technology Present invention reaction temperature, ° C. 620 620 feed temperature, ° C. 400 400 regeneration temperature, ° C. 700 700 temperature of regenerated 695 655 catalyst entering the downer reactor, ° C. catalyst-to-oil ratio, 16.5 30 weight/weight reaction time, second 0.6 0.6

TABLE-US-00007 TABLE 7 Properties of mixed C4 raw material and test results Items Components of raw material: mol % Parameters Present invention C.sub.3 + C.sub.5 0.6 butane 11.9 butene 87.5 Total 100 <C2 15.8 wherein ethylene 10.6 propane 4.3 propylene 47.2 butane 10.3 butene 11.7 liquid + coke + loss 10.7 wherein ethylene + propylene 57.8 Total 100

[0094] The above embodiments are merely illustrative of the principles and advantages of the present invention, and are not to limit the present invention. Any skilled in the art can make modifications and changes to the embodiments described above without departing from the spirit and scope of the present invention. Accordingly, any equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concepts of the present invention should be covered by the appended claims.