Catalytic cracking method with high yield of ethylene and propylene

Abstract

The invention provides a catalytic cracking method with high yield of ethylene and propylene, which comprises the following steps: (1) introducing a preheated raw material and water vapor into a dense-phase fluidized bed reactor from a feeding nozzle to contact with a catalyst and react to obtain a reaction oil agent; the average solid content of the catalyst in the dense-phase fluidized bed reactor is 0.2-0.7; the plurality of feeding nozzles are distributed on the plurality of concentric rings, the plurality of concentric rings are concentric with the cross section of the dense-phase fluidized bed reactor, the number of the concentric rings is greater than or equal to 2, the ratio of the radius of each concentric ring to the radius of the cross section is (0.1-0.9): 1, the number of the feeding nozzles distributed on each concentric ring is greater than 2, and the feeding nozzles on each concentric ring are uniformly distributed; and (2) carrying out gas-solid separation on the reaction oil agent to obtain a product containing ethylene and propylene. According to the method, the thermal cracking reaction degree is reduced, the catalytic cracking reaction proportion is remarkably increased, and the yield of methane and coke can be remarkably reduced while high ethylene and propylene yields are obtained.

Description

Technical Field

[0001] This invention relates to the field of catalytic cracking for the production of low-carbon olefins, and specifically to a catalytic cracking method for high yields of ethylene and propylene. Background Technology

[0002] As important organic chemical raw materials, ethylene and propylene play irreplaceable roles in many fields such as chemical engineering, agriculture, and medicine. Domestically and internationally, low-carbon olefins are mainly produced using light hydrocarbons or light naphtha fractions as feedstocks through steam cracking processes. Although steam cracking technology has been continuously improved over decades, it still suffers from technical limitations such as difficulty in adjusting product structure, high energy consumption, high production costs, and large CO2 emissions. Catalytic cracking technology, as an important secondary crude oil processing technology, is increasingly valued for its advantages such as strong feedstock adaptability and flexible product formulation. In particular, the invention of the ZSM-5 molecular sieve has driven the advancement of catalytic cracking technology in the production of low-carbon olefins.

[0003] Numerous research institutions and petrochemical companies, both domestically and internationally, have developed catalytic cracking technologies with independent intellectual property rights for the production of low-carbon olefins, resulting in typical processes such as DCC, Maxofin, and PetroFCC. Over the past few decades, researchers have continuously optimized and redesigned catalytic cracking processes and catalysts, leading to continuously improved yields of low-carbon olefins while simultaneously reducing dry gas and coke yields. Patents generated during this research process primarily focus on developing different reactor technologies, such as variable-diameter riser reactors, dual-riser reactors, downflow reactors, and riser + fluidized bed reactors; and developing various specialized catalyst preparation technologies, mainly including shape-selective molecular sieve ZSM-5 modification, Y zeolite, and matrix composition modification. These catalytic cracking technologies, using heavy oil as feedstock, have achieved 2-6% ethylene yields, 15-25% propylene yields, and 10-20% butene yields. While existing catalytic cracking technologies can achieve high propylene and butene yields, ethylene yields are low, and research on this technology is limited.

[0004] The patent, entitled "A Catalytic Thermal Cracking Method for Producing Ethylene and Propylene from Petroleum Hydrocarbons," describes a process where petroleum hydrocarbon feedstock is fed into a riser reactor and contacted with a hot, five-membered ring-containing high-silica zeolite catalyst. The catalytic thermal cracking reaction is carried out at a reaction temperature of 550-700°C, a reaction pressure of 150-400 kPa, a catalyst-to-feedstock oil weight ratio of 15-40:1, and a steam-to-feedstock oil weight ratio of 0.3-1:1. This patent utilizes a phosphorus- and transition metal-containing five-membered ring high-silica zeolite catalyst with low hydrogen transfer activity and high ethylene selectivity. By increasing the reaction temperature, the yield of low-carbon olefins is increased, particularly the yield of ethylene.

[0005] The patented invention, entitled "Method for Direct Conversion of Heavy Hydrocarbons to Ethylene," describes a conversion reaction between a solid particulate contact agent and feedstock oil in a fluidized bed or plug flow reactor, particularly a riser or downflow reactor. The main reaction conditions are 650-900℃, pressure 0.13-0.28 MPa, agent-to-oil ratio 5-35, and contact time 0.1-3.0 seconds. This patent utilizes an aluminosilicate contact agent modified with alkaline or alkaline earth metal oxides. Under conditions not exceeding the tubular furnace pyrolysis temperature, it achieves high yields of low-carbon olefins, with an ethylene yield of 17-27% and a total yield of ethylene, propylene, and butene of 30-40%.

[0006] The above patents can achieve high ethylene yields, but the generation of low-value byproducts such as methane and coke is difficult to control. In non-hydrogen-dependent catalytic conversion processes, how to convert more petroleum hydrocarbons and other feedstocks into ethylene and propylene, while simultaneously achieving high ethylene and propylene yields and reducing methane and coke yields, is a pressing technical problem that needs to be solved. Summary of the Invention

[0007] To address the above problems, this invention provides a catalytic cracking method for high yields of ethylene and propylene.

[0008] This invention provides a catalytic cracking method for high yields of ethylene and propylene, comprising the following steps:

[0009] (1) The preheated raw materials and steam are introduced into the dense phase fluidized bed reactor through the feed nozzle to contact the catalyst and react to obtain the reaction oil.

[0010] The average solid content of the catalyst in the dense-phase fluidized bed reactor is 0.2 to 0.7.

[0011] The feed nozzles are multiple and distributed on multiple concentric rings. The multiple concentric rings are concentric with the cross-section of the dense phase fluidized bed reactor. The number of concentric rings is greater than or equal to 2. The ratio of the radius of each concentric ring to the radius of the cross-section is 0.1 to 0.9:1. The number of feed nozzles distributed on each concentric ring is greater than 2. The feed nozzles on each concentric ring are evenly distributed.

[0012] (2) The reaction oil is subjected to gas-solid separation to obtain a coking catalyst and a reaction oil gas; the reaction oil gas is separated to obtain products including ethylene and propylene; the coking catalyst is stripped and then introduced into a regenerator for regeneration, and the resulting regenerated catalyst is returned to the dense phase fluidized bed reactor for recycling.

[0013] Optionally, the average solid content of the catalyst in the dense phase fluidized bed reactor is 0.3 to 0.5.

[0014] Optionally, the number of concentric rings is 2 to 4; multiple concentric rings are located at the bottom of the dense phase fluidized bed reactor.

[0015] Optionally, the ratio of the radius of each concentric ring to the radius of the cross section is 0.2 to 0.8:1, and the radii of the multiple concentric rings and the cross section are distributed in an arithmetic progression.

[0016] Optionally, the number of feed nozzles distributed on each concentric ring is greater than or equal to 4, and the number of feed nozzles distributed on the concentric ring with a larger radius is greater than the number of feed nozzles distributed on the concentric ring with a smaller radius.

[0017] Preferably, the number of feed nozzles distributed on each of the concentric rings is a×2. (n-1) , where a is the number of feed nozzles distributed on the concentric ring with the smallest radius, and n is the number of rings of the concentric ring.

[0018] Optionally, the angle between the axis of the feed nozzle and the axis of the dense phase fluidized bed reactor is 0 to 50°, preferably 0 to 20°.

[0019] Optionally, the dense phase fluidized bed reactor is one or a combination of two of the following: a constant diameter fluidized bed and a variable diameter fluidized bed.

[0020] Optionally, the catalyst comprises 10-80 wt% clay, 10-80 wt% inorganic oxides and 10-80 wt% zeolite;

[0021] The clay used as a matrix is ​​selected from one or more of the following: kaolin, hydrous kaolin, sepiolite, attapulgite, montmorillonite, and pyroxene.

[0022] The inorganic oxide used as a binder is selected from one or more of alumina, silicon oxide, amorphous aluminum silicate, and aluminum phosphate sol.

[0023] The zeolite is selected from one or more of the ZSM series zeolite, β series zeolite, and Y-type series zeolite, or from one or more of the ZSM series zeolite, β series zeolite, and Y-type series zeolite modified with non-metallic elements and / or metallic elements. The non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

[0024] Optionally, the catalyst comprises 15-70 wt% clay, 15-70 wt% inorganic oxides and 15-70 wt% zeolite;

[0025] Wherein, the clay is kaolin and / or hydrous kaolin, the inorganic oxide is silicon dioxide and / or aluminum oxide, the zeolite is selected from one or more of the ZSM series zeolite, β series zeolite, and Y series zeolite modified with non-metallic elements and / or metallic elements, the non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

[0026] Optionally, the reaction conditions of the dense-phase fluidized bed reactor include:

[0027] The reaction temperature is 500–750℃, the reaction pressure is 0.10–0.20 MPa, the agent-to-oil mass ratio is 5–50:1, the water-to-oil mass ratio is 0.1–1:1, the oil-to-agent contact time is 0.1–20 seconds, and the height-to-diameter ratio of the reactor is 0.5–20:1.

[0028] Preferably, the reaction temperature is 600-700℃, the reaction pressure is 0.11-0.14MPa, the agent-to-oil mass ratio is 10-30:1, the water-to-oil mass ratio is 0.3-0.6:1, the oil-to-agent contact time is 1-10 seconds, and the height-to-diameter ratio of the reactor is 2-10:1.

[0029] Optionally, the raw material is selected from one or more of petroleum hydrocarbons, animal and vegetable oils, synthetic oils, and biomass, wherein the petroleum hydrocarbons are petroleum hydrocarbons with a carbon number greater than or equal to 4.

[0030] Beneficial effects:

[0031] In the catalytic cracking method of this invention, the catalytic cracking feedstock is introduced into a dense-phase fluidized bed reactor through feed nozzles with concentric ring distribution. After contacting the catalyst, it rises to carry out the catalytic reaction. At the same time, the average solid content of the catalyst in the dense-phase fluidized bed reactor is controlled, which can make the hydrocarbon molecules in the feedstock more uniform and sufficient in contact with the active centers of the catalyst, reduce the degree of thermal cracking reaction, and significantly increase the proportion of catalytic cracking reaction. This can achieve high ethylene and propylene yields while significantly reducing methane and coke yields. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a specific embodiment of the catalytic cracking reaction system applicable to the catalytic cracking method for high ethylene and propylene yields of the present invention;

[0033] Figure 2 This is a schematic diagram of a specific implementation where the feed nozzles are distributed in multiple concentric rings with the same center as the cross-section of the dense phase fluidized bed reactor;

[0034] Figure 3 This is a schematic diagram of a specific implementation of the angle α between the axis of the feed nozzle and the axis of the dense phase fluidized bed reactor;

[0035] Explanation of reference numerals in the attached figures

[0036] 1. Dense phase fluidized bed reactor 2. Regenerator

[0037] 3 stripper 4 settling tank

[0038] 11 Concentric rings 12 Pre-lift steam pipeline

[0039] 13 Oil discharge pipe 14 Cross section

[0040] 21 Air delivery pipe 22 Second cyclone separator

[0041] 23 Regenerated flue gas conveying pipe 24 Regenerated catalyst conveying pipe

[0042] 31 Stripping steam conveying pipe; 32 Catalyst waiting conveying pipe

[0043] 41 First cyclone separator 42 Oil and gas output pipe

[0044] Angle between the axis of the feed nozzle (Aa) and the axis of the dense phase fluidized bed reactor (α) Detailed Implementation

[0046] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0047] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0048] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0049] This invention provides a catalytic cracking method for high yields of ethylene and propylene, comprising the following steps:

[0050] (1) The preheated raw materials and steam are introduced into the dense phase fluidized bed reactor 1 through the feed nozzle Aa to contact the catalyst and react to obtain the reaction oil.

[0051] The average solid content of the catalyst in the dense phase fluidized bed reactor 1 is 0.2 to 0.7.

[0052] The feed nozzles Aa are multiple and distributed on multiple concentric rings 11. The multiple concentric rings 11 are concentric with the cross section 14 of the dense phase fluidized bed reactor 1. The number of concentric rings 11 is greater than or equal to 2. The ratio of the radius of each concentric ring 11 to the radius of the cross section 14 is 0.1 to 0.9:1. The number of feed nozzles Aa distributed on each concentric ring 11 is greater than 2. The feed nozzles Aa on each concentric ring 11 are evenly distributed.

[0053] (2) The reaction oil is subjected to gas-solid separation to obtain a coking catalyst and a reaction oil gas; the reaction oil gas is separated to obtain products including ethylene and propylene; the coking catalyst is stripped and then introduced into a regenerator for regeneration, and the resulting regenerated catalyst is returned to the dense phase fluidized bed reactor for recycling.

[0054] It should be noted that in the catalytic cracking method of the present invention, there are multiple feed nozzles Aa distributed on multiple concentric rings 11. All the feed nozzles on these concentric rings can be located in the same plane, coplanar with and concentric with a cross-section at the bottom or lower part of the dense-phase fluidized bed reactor. The multiple concentric rings and the cross-section of the dense-phase fluidized bed reactor can be on the same horizontal plane, and the radius of the multiple concentric rings and the radius of this coplanar cross-section satisfy the aforementioned ratio relationship. The catalyst can be introduced into the dense-phase fluidized bed reactor from the bottom and flows upward under the lifting action of pre-lifting steam. The feed nozzles can be distributed on multiple concentric rings located at the bottom of the dense-phase fluidized bed reactor. The raw material, steam, and catalyst all flow upward into the dense-phase fluidized bed reactor for catalytic cracking reaction. Furthermore, the multiple feed nozzles Aa distributed on multiple concentric rings 11 can be multiple concentric annular feed pipes (including but not limited to this embodiment), where multiple concentric rings 11 represent multiple concentric circular rings.

[0055] Through years of research and development, the inventors of this application unexpectedly discovered that distributing the feed nozzles in the form of ≥2 concentric rings, with multiple concentric rings arranged concentrically with the cross-section of the dense phase fluidized bed reactor, and the ratio of the radius of any concentric ring to the radius of the cross-section being 0.1 to 0.9:1, with ≥2 feed nozzles arranged on each concentric ring, and the feed nozzles on each concentric ring being uniformly distributed, allows the feed material and water vapor to be introduced through feed nozzles that meet these arrangement characteristics. Then, together with the catalyst, the feed material and water vapor rise within the dense phase fluidized bed reactor to carry out catalytic cracking reactions with an average catalyst solid content of 0.2 to 0.7%. This enables hydrocarbon molecules in the feed material to have more uniform and sufficient contact with the active centers of the catalyst, reduces the degree of thermal cracking reaction, and significantly increases the proportion of catalytic cracking reaction. This allows for the achievement of high ethylene and propylene yields while significantly reducing methane and coke yields.

[0056] The catalyst solid content in this invention is obtained as follows:

[0057] Catalyst solid content = Pressure difference between two points along the reactor axis (measured by a differential pressure gauge) ÷ Distance between the two points along the axis ÷ Catalyst particle density; where the unit of pressure difference is kg / m³. 2 The distance between two points along the axis is in meters (m), and the catalyst particle density is kg / m³. 3 The two points along the axial direction are any two points along the axial direction of the reactor.

[0058] For the average solids content of the catalyst, the two selected axial points are the bottom and top of the reactor, respectively. The distance between the two points represents the height of the reactor, and the pressure difference between them represents the pressure difference between the top and bottom of the reactor.

[0059] In one embodiment of the aforementioned catalytic cracking method of the present invention, the average solid content of the catalyst in the dense phase fluidized bed reactor is 0.3 to 0.5.

[0060] It should be noted that in the catalytic cracking method of the present invention with concentric ring distribution of feed nozzles, by controlling the average solid content of the catalyst in the dense phase fluidized bed reactor to be 0.3 to 0.5, the yields of ethylene and propylene, as well as the yield ratio of diene / (methane + coke), can be further improved.

[0061] In another embodiment of the aforementioned catalytic cracking method of the present invention, the number of concentric rings is 2 to 4;

[0062] Multiple concentric rings are located at the bottom of the dense-phase fluidized bed reactor.

[0063] It should be noted that multiple concentric rings equipped with feed nozzles are located at the bottom of the dense-phase fluidized bed reactor. The feedstock and steam are then injected into the reactor through these nozzles. The catalyst can be introduced through a riser pipe below the reactor, rising upwards from the bottom. By controlling the number of concentric rings to 2–4, the yields of ethylene and propylene can be further improved.

[0064] In one embodiment of the aforementioned catalytic cracking method of the present invention, the ratio of the radius of each concentric ring to the radius of the cross-section is 0.2 to 0.8:1, and the radii of the multiple concentric rings and the cross-section are distributed in an arithmetic progression.

[0065] It should be noted that the ratio of the radius of any concentric ring to the radius of the cross-section is controlled within the range of 0.2 to 0.8:1, and the radius of different concentric rings is different. The radii of multiple concentric rings are distributed in an arithmetic progression from small to large with respect to the radius of the cross-section. With such a cleverly designed concentric ring, the raw materials introduced by the feed nozzles distributed on it can be converted into more ethylene and propylene after entering the dense phase fluidized bed reactor, while reducing the generation of coke and methane.

[0066] In one embodiment of the catalytic cracking method described above in this invention, the number of feed nozzles distributed on each concentric ring is greater than or equal to 4, and the number of feed nozzles distributed on the concentric ring with a larger radius is greater than the number of feed nozzles distributed on the concentric ring with a smaller radius.

[0067] Preferably, the number of feed nozzles distributed on each of the concentric rings is a×2. (n-1) , where a is the number of feed nozzles distributed on the concentric ring with the smallest radius, and n is the number of rings of the concentric ring.

[0068] The following discussion focuses on the number of rings n and the number of feed nozzles a×2 distributed on the concentric rings. (n-1) Explanation:

[0069] The number of concentric rings with the smallest radius (closest to the center of the cross-section) is n, which is 1, and the number of feed nozzles distributed on it is a;

[0070] The number of concentric rings n adjacent to the concentric ring with the smallest radius (with a gap of 0) is 2, and the number of feed nozzles distributed on it is 2a;

[0071] The number of concentric rings n, which are separated from the smallest concentric ring by one concentric ring, is 3, and the number of feed nozzles distributed on them is 4a.

[0072] ...

[0073] The number of concentric rings n-2 rings apart from the smallest concentric ring is n, and the number of feed nozzles distributed on them is a×2. (n-1) .

[0074] In the catalytic cracking method of this invention, under the premise of controlling the radius of the concentric rings and the reactor cross-section to be evenly distributed, the radius of the concentric rings is further increased to increase the number of nozzles. The number of feed nozzles distributed on any concentric ring is at least 4, and the number of nozzles on the concentric rings with ring number n satisfies a×2. (n-1) This arrangement of the feed nozzles allows for a clever mixing and contact between the raw materials and the catalyst, enabling the catalyst to exhibit better ethylene and propylene catalytic activity. More raw materials are catalytically converted into ethylene and propylene, while reducing the generation of coke and methane, further improving the diene / (methane + coke) yield ratio.

[0075] In one embodiment of the aforementioned catalytic cracking method of the present invention, such as Figure 3 As shown, the angle α between the axis of the feed nozzle and the axis of the dense phase fluidized bed reactor is 0 to 50°, preferably 0 to 20°.

[0076] In the catalytic cracking method of the present invention, under the premise of controlling the concentric rings and the arrangement of the feed nozzles as described above, further controlling the angle α between the axis of the feed nozzle and the axis of the dense phase fluidized bed reactor as described above can better improve the yield of ethylene and propylene, and reduce the generation of low-value products such as coke and methane.

[0077] In one embodiment of the aforementioned catalytic cracking method of the present invention, the dense phase fluidized bed reactor is one or a combination of two of the following: a fluidized bed with constant diameter and a fluidized bed with variable diameter.

[0078] Using a fluidized bed of equal diameter or a fluidized bed of varying diameter, or a combination of fluidized beds of equal diameter and varying diameter, as a dense-phase fluidized bed reactor enables the catalytic cracking method of the present invention to operate stably and obtain a high diene / (methane + coke) yield ratio.

[0079] It should be noted that by controlling the reaction oil to exit the reactor from the top, controlling the reactor structure (e.g., height-to-diameter ratio), and controlling reaction conditions (e.g., agent-to-oil mass ratio, water-to-oil mass ratio), the average solid content of the catalyst in the dense-phase fluidized bed reactor can be regulated as described above. Furthermore, as a preferred embodiment, the catalyst solid content in the aforementioned dense-phase fluidized bed reactor can be controlled to exhibit a gentle gradient distribution along the axial direction, gradually decreasing from bottom to top.

[0080] The phrase "the catalyst solid content exhibits a gentle gradient distribution that gradually decreases from bottom to top along the axial direction" means that, in the curve of catalyst solid content G versus the ratio of the height h from the bottom of the reactor to the total height H of the reactor, within the range of h / H of 10%-90%, the difference ΔG between any two points where h / H differs by 10% is not greater than 0.2.

[0081] In this preferred embodiment, in the method system of setting the feed nozzles into multiple concentric rings in the above-described ingenious manner and controlling the average solid content of the catalyst in the dense phase fluidized bed reactor, as described above, the catalyst solid content in the dense phase fluidized bed reactor exhibits a gentle gradient distribution characteristic that gradually decreases from bottom to top along the axial direction. Such a gentle gradient distribution is conducive to the catalyst better exerting its catalytic activity as ethylene and propylene products, further reducing the degree of thermal cracking reaction and increasing the proportion of catalytic cracking reaction, thereby significantly increasing the yield of ethylene and propylene in the catalytic cracking reaction, while also reducing the yield of coke and methane, and obtaining a higher diene / (methane + coke) yield ratio.

[0082] In one embodiment of the aforementioned catalytic cracking method of the present invention, the catalyst comprises 10-80 wt% clay, 10-80 wt% inorganic oxides and 10-80 wt% zeolite;

[0083] The clay used as a matrix is ​​selected from one or more of the following: kaolin, hydrous kaolin, sepiolite, attapulgite, montmorillonite, and pyroxene.

[0084] The inorganic oxide used as a binder is selected from one or more of alumina, silicon oxide, amorphous aluminum silicate, and aluminum phosphate sol.

[0085] The zeolite is selected from one or more of the ZSM series zeolite, β series zeolite, and Y-type series zeolite, or from one or more of the ZSM series zeolite, β series zeolite, and Y-type series zeolite modified with non-metallic elements and / or metallic elements. The non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

[0086] The catalysts composed of one or more of the ZSM series zeolites, β series zeolites, Y series zeolites and their modified zeolites as described above, along with clay matrix and inorganic oxide binders, are well-suited for the catalytic cracking method of the present invention and achieve high yields of low-carbon olefins.

[0087] In one embodiment of the aforementioned catalytic cracking method of the present invention, the catalyst comprises 15-70 wt% clay, 15-70 wt% inorganic oxides and 15-70 wt% zeolite;

[0088] Wherein, the clay is kaolin and / or hydrous kaolin, the inorganic oxide is silicon dioxide and / or aluminum oxide, the zeolite is selected from one or more of the ZSM series zeolite, β series zeolite, and Y series zeolite modified with non-metallic elements and / or metallic elements, the non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

[0089] In another embodiment of the aforementioned catalytic cracking method of the present invention, the reaction conditions of the dense-phase fluidized bed reactor include:

[0090] The reaction temperature is 500–750℃, the reaction pressure is 0.10–0.20 MPa, the agent-to-oil mass ratio is 5–50:1, the water-to-oil mass ratio is 0.1–1:1, the oil-to-agent contact time is 0.1–20 seconds, and the height-to-diameter ratio of the reactor is 0.5–20:1.

[0091] Preferably, the reaction temperature is 600-700℃, the reaction pressure is 0.11-0.14MPa, the agent-to-oil mass ratio is 10-30:1, the water-to-oil mass ratio is 0.3-0.6:1, the oil-to-agent contact time is 1-10 seconds, and the height-to-diameter ratio of the reactor is 2-10:1.

[0092] In the method of the present invention, by controlling the reaction conditions of the dense phase fluidized bed reactor as described above, the catalyst solid content in the reactor can be better controlled, so that the raw materials and catalyst can carry out catalytic cracking reaction stably, and high ethylene and propylene yields can be obtained, while reducing the generation of low-value products.

[0093] In one embodiment of the aforementioned catalytic cracking method of the present invention, the raw material is selected from one or more of petroleum hydrocarbons, animal and vegetable oils, synthetic oils, and biomass, wherein the petroleum hydrocarbons are petroleum hydrocarbons with a carbon number greater than or equal to 4.

[0094] As a preferred embodiment, petroleum hydrocarbons with a carbon number greater than or equal to 4 are used as raw materials and introduced into the dense phase fluidized bed reactor through feed nozzles with concentric rings to react with the catalyst. This can significantly increase the yield of ethylene and propylene and reduce the yield of coke + methane.

[0095] In addition, the present invention may also provide a catalytic cracking reaction system for carrying out the above-described catalytic cracking method of the present invention, such as... Figure 1 and Figure 2 As shown, it includes a dense phase fluidized bed reactor 1, a regenerator 2, a stripper 3, and a settling tank 4;

[0096] The bottom or lower part of the dense phase fluidized bed reactor 1 is provided with feed nozzles Aa. There are multiple feed nozzles Aa and they are distributed on multiple concentric rings 11. The multiple concentric rings 11 are concentric with the cross section 14 of the dense phase fluidized bed reactor 1. The number of concentric rings 11 is greater than or equal to 2. The ratio of the radius of each concentric ring 11 to the radius of the cross section 14 is 0.1 to 0.9:1. The number of feed nozzles Aa distributed on each concentric ring 11 is greater than 2. The feed nozzles Aa on each concentric ring 11 are evenly distributed.

[0097] The bottom or lower part of the dense phase fluidized bed reactor 1 is provided with a catalyst inlet, which is connected to the pre-lift steam pipeline 12;

[0098] The settling tank 4 is equipped with a first cyclone separator 41. The oil outlet of the dense phase fluidized bed reactor 1 is connected to the inlet of the first cyclone separator 41 via an oil outlet pipe 13. The top of the settling tank 4 is equipped with an oil and gas outlet pipe 42.

[0099] The stripper 3 can be located below the settling tank 4. The stripper 3 is equipped with a stripping steam conveying pipe 31. The catalyst outlet of the stripper 3 is connected to the catalyst inlet of the regenerator 2 via a catalyst delivery pipe 32.

[0100] The regenerator 2 is equipped with an air delivery pipe 21, a second cyclone separator 22, a regenerated flue gas delivery pipe 23, and a regenerated catalyst delivery pipe 24. The catalyst outlet of the regenerator 2 is connected to the catalyst inlet at the bottom or lower part of the dense phase fluidized bed reactor 1 via the regenerated catalyst delivery pipe 24.

[0101] like Figure 1 As shown, the hot regenerated catalyst is introduced into the bottom of the dense phase fluidized bed reactor 1 through the regenerated catalyst conveying pipe 24 and flows upward under the action of the pre-lifting medium. The feedstock and steam are injected into the bottom of the dense phase fluidized bed reactor 1 through the feed nozzle Aa, contacting the regenerated catalyst and undergoing catalytic cracking reaction in the reactor 1. The reacted oil is separated from the catalyst in the settling tank 4 through the oil outlet pipe 13. The carbonized catalyst enters the stripper 3, where the hydrocarbon products adsorbed on the catalyst are stripped and then sent to the regenerator 2 for regeneration through the spent catalyst conveying pipe 32. The regenerated catalyst is returned to the dense phase fluidized bed reactor 1 for reuse. The separated oil and gas enter the subsequent separation system through the oil and gas outlet pipe 42. After separation, dry gas, liquefied petroleum gas, gasoline, diesel, and heavy oil can be obtained. Further separation can yield products such as ethylene and propylene. The feed nozzles can be distributed on multiple annular feed pipes concentric with the cross-section of the dense phase fluidized bed reactor. The multiple annular feed pipes are distributed in concentric rings, and the nozzles on each ring are evenly distributed.

[0102] The present invention will be further described in detail below through examples, but these examples are not intended to limit the invention. In the following examples, unless otherwise specified, the experimental instruments and raw materials involved are all commercially available products.

[0103] The feedstock used in the examples and comparative examples was atmospheric residue oil, the properties of which are shown in Table 1. The properties of the catalyst used are shown in Table 2. The dense-phase fluidized bed reactor in the examples was a fluidized bed of equal diameter.

[0104] Table 1

[0105]

[0106] Table 2

[0107]

[0108] The molecular sieve, matrix, and binder of the catalyst were purchased from Sinopec Catalyst Qilu Branch. The catalyst consists of 30% phosphorus and iron-modified ZSM-5 molecular sieve, 42% kaolin, and 28% Al2O3 binder. The phosphorus modifier is ammonium dihydrogen phosphate, and the iron modifier is ferric nitrate. The molecular sieve, matrix, and binder are mixed and slurried, then sequentially spray-dried, washed, filtered, and dried. Before use, the catalyst is aged at 800℃ with 100% steam for 2 hours.

[0109] Example 1

[0110] exist Figure 1The experiment was conducted in a system using atmospheric residue oil as feedstock and heavy oil cracking catalyst as catalyst. During the experiment, hot regenerated catalyst was introduced into the bottom of the dense-phase fluidized bed reactor. Preheated atmospheric residue oil and steam were injected into the bottom of the reactor through the feed nozzle, contacting the regenerated catalyst and undergoing catalytic cracking reaction in the reactor. The reacted oil was introduced into an oil separation system, and the separated reaction oil and gas entered a subsequent product separation system. The separated catalyst was stripped and then introduced into a regenerator for coke regeneration. The regenerated catalyst was returned to the dense-phase fluidized bed reactor for recycling. The feed nozzles were distributed on two concentric rings with the bottom cross-section of the dense-phase fluidized bed reactor as the center. The concentric rings were located at 1 / 3 and 2 / 3 of the cross-sectional radius of the reactor, respectively, with 4 and 8 nozzles on each ring (the feed nozzles were evenly distributed on each ring, with larger rings having more nozzles). The nozzle axes were aligned with the reactor axis. The unit used electric heating to maintain the temperature of the reaction and regeneration systems. The main operating conditions and results are listed in Table 3.

[0111] Comparative Example 1

[0112] The raw materials and catalysts used, as well as the main implementation steps, are the same as in Example 1. The difference is that the feed is located at the bottom of the dense phase fluidized bed reactor and is injected into the reactor through two nozzles. The main operating conditions and results are listed in Table 3.

[0113] Example 2

[0114] The raw materials, catalysts, and main implementation steps used are the same as in Example 1. The difference is that the feed nozzles are distributed on four concentric rings with the bottom cross-section of the dense phase fluidized bed reactor as the center. The concentric rings are distributed at 1 / 5, 2 / 5, 3 / 5, and 4 / 5 of the radius of the cross-section of the dense phase fluidized bed reactor, respectively. The number of nozzles on each concentric ring is 4, 8, 16, and 32, respectively (the feed nozzles on each concentric ring are evenly distributed, and the larger the radius of the concentric ring, the more nozzles there are). The main operating conditions and results are listed in Table 3.

[0115] Table 3

[0116]

[0117] As can be seen from the data in Table 3, the catalytic cracking method provided by the present invention has the effect of significantly improving the yield of ethylene and propylene and increasing the diene / (methane + coke) ratio. In particular, in Example 2, while controlling the average solid content of the catalyst, the method cleverly designs four concentric rings with 4, 8, 16 and 32 nozzles respectively distributed on them, which further significantly improves the diene yield and the diene / (methane + coke) yield ratio.

[0118] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0119] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0120] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A catalytic cracking process with high ethylene and propylene yield, characterized by, Includes the following steps: (1) The preheated raw materials and steam are introduced into the dense phase fluidized bed reactor through the feed nozzle to contact the catalyst and react to obtain the reaction oil. The average solid content of the catalyst in the dense-phase fluidized bed reactor is 0.2 to 0.

7. The feed nozzles are multiple and distributed on multiple concentric rings. The multiple concentric rings are concentric with the cross-section of the dense phase fluidized bed reactor. The number of concentric rings is greater than or equal to 2. The ratio of the radius of each concentric ring to the radius of the cross-section is 0.1 to 0.9:

1. The number of feed nozzles distributed on each concentric ring is greater than 2. The feed nozzles on each concentric ring are evenly distributed. (2) The reaction oil is subjected to gas-solid separation to obtain a coking catalyst and a reaction oil gas; the reaction oil gas is separated to obtain products including ethylene and propylene; the coking catalyst is stripped and then introduced into a regenerator for regeneration, and the resulting regenerated catalyst is returned to the dense phase fluidized bed reactor for recycling.

2. The catalytic cracking process of claim 1 wherein, The average solid content of the catalyst in the dense phase fluidized bed reactor is 0.3 to 0.5%.

3. The catalytic cracking process of claim 1 wherein, The number of concentric rings is 2 to 4; Multiple concentric rings are located at the bottom of the dense-phase fluidized bed reactor.

4. The catalytic cracking process of claim 1 wherein, The ratio of the radius of each concentric ring to the radius of the cross-section is 0.2 to 0.8:1, and the radii of the multiple concentric rings and the cross-section are distributed in an arithmetic progression.

5. The catalytic cracking process of claim 1 wherein, The number of feed nozzles distributed on each concentric ring is greater than or equal to 4, and the number of feed nozzles distributed on the concentric ring with a larger radius is greater than the number of feed nozzles distributed on the concentric ring with a smaller radius. Preferably, the number of said feed nozzles distributed on each said concentric ring is a x 2 (n-1) wherein a is the number of said feed nozzles distributed on the concentric ring with the smallest radius and n is the number of said concentric rings.

6. The catalytic cracking process of claim 1 wherein, The angle between the axis of the feed nozzle and the axis of the dense phase fluidized bed reactor is 0 to 50°, preferably 0 to 20°.

7. The catalytic cracking method according to claim 1, characterized in that, The dense phase fluidized bed reactor is one or a combination of two of the following: a constant diameter fluidized bed and a variable diameter fluidized bed.

8. The catalytic cracking method according to claim 1, characterized in that, The catalyst comprises 10–80 wt% clay, 10–80 wt% inorganic oxides and 10–80 wt% zeolite; The clay used as a matrix is ​​selected from one or more of the following: kaolin, hydrous kaolin, sepiolite, attapulgite, montmorillonite, and pyroxene. The inorganic oxide used as a binder is selected from one or more of alumina, silicon oxide, amorphous aluminum silicate, and aluminum phosphate sol. The zeolite is selected from one or more of the ZSM series zeolite, β series zeolite, and Y-type series zeolite, or from one or more of the ZSM series zeolite, β series zeolite, and Y-type series zeolite modified with non-metallic elements and / or metallic elements. The non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

9. The catalytic cracking method according to claim 8, characterized in that, The catalyst comprises 15-70 wt% clay, 15-70 wt% inorganic oxides and 15-70 wt% zeolite; Wherein, the clay is kaolin and / or hydrous kaolin, the inorganic oxide is silicon dioxide and / or aluminum oxide, the zeolite is selected from one or more of the ZSM series zeolite, β series zeolite, and Y series zeolite modified with non-metallic elements and / or metallic elements, the non-metallic elements include phosphorus, and the metallic elements are selected from one or more of iron, cobalt, nickel, magnesium, calcium, and rare earth elements.

10. The catalytic cracking method according to claim 1, characterized in that, The reaction conditions of the dense-phase fluidized bed reactor include: The reaction temperature is 500–750℃, the reaction pressure is 0.10–0.20 MPa, the agent-to-oil mass ratio is 5–50:1, the water-to-oil mass ratio is 0.1–1:1, the oil-to-agent contact time is 0.1–20 seconds, and the height-to-diameter ratio of the reactor is 0.5–20:

1. Preferably, the reaction temperature is 600-700℃, the reaction pressure is 0.11-0.14MPa, the agent-to-oil mass ratio is 10-30:1, the water-to-oil mass ratio is 0.3-0.6:1, the oil-to-agent contact time is 1-10 seconds, and the height-to-diameter ratio of the reactor is 2-10:

1.

11. The catalytic cracking method according to claim 1, characterized in that, The raw materials are selected from one or more of petroleum hydrocarbons, animal and vegetable oils, synthetic oils, and biomass, wherein the petroleum hydrocarbons are petroleum hydrocarbons with a carbon number greater than or equal to 4.

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