Reducing fluidized bed for preparing olefin from synthesis gas and method thereof

Abstract

The invention discloses a variable-diameter fluidized bed for preparing olefin from synthesis gas and a method thereof, gradient optimization of reaction conditions is realized by arranging the variable-diameter fluidized bed, and good gas-solid contact and fluidization states in the whole reaction path can be maintained, so that the per-pass conversion rate of reactants and the selectivity of target olefin are improved, and the yield of olefin is increased. And the circulation amount of unreacted raw materials is reduced, and the operation cost is reduced.

Description

Technical Field

[0001] This application belongs to the field of chemical and chemical manufacturing technology, specifically relating to a variable-diameter fluidized bed and method for preparing olefins from syngas. Background Technology

[0002] Syngas to olefins is a novel catalytic reaction route. Its advantages include a short process, low investment, wide applicability of raw materials, and low separation energy consumption, thus attracting widespread attention.

[0003] However, the synthesis of olefins from syngas is a molecular reduction reaction. As the reaction conversion rate increases, the gas velocity above the catalyst decreases, resulting in poor gas-solid contact. Unreacted feedstock needs to be separated and recycled, leading to increased operating costs. Summary of the Invention

[0004] This application aims to provide a variable-diameter fluidized bed and method for syngas to olefins. By setting up a variable-diameter fluidized bed, the reaction conditions are optimized by gradient, which can maintain good gas-solid contact and fluidization state throughout the reaction path, thereby improving the single-pass conversion rate of reactants and the selectivity of target olefins, reducing the amount of unreacted feedstock recycled, and lowering operating costs.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application propose a variable-diameter fluidized bed for the preparation of olefins from syngas, the fluidized bed comprising: First reaction zone (1) and second reaction zone (2); The first reaction zone (1) has an air inlet (11) and an air outlet (12) at opposite ends in a first direction, with the air outlet (12) located above the air inlet (11); the air inlet (11) is used to introduce synthesis gas into the first reaction zone (1); The first reaction zone (1) is filled with a catalyst; The first reaction zone (1) and the second reaction zone (2) are connected in the first direction, and the second reaction zone (2) is located above the first reaction zone (1). The air outlet (12) is connected to the interior of the second reaction zone (2). The diameter of the first reaction zone (1) in the second direction perpendicular to the first direction is greater than the diameter of the second reaction zone (2) in the second direction.

[0006] Optionally, the diameter of the first reaction zone (1) in the second direction is 1.5-3 times the diameter of the second reaction zone (2) in the second direction.

[0007] Optionally, the ratio of the height of the first reaction zone (1) in the first direction to its diameter in the second direction is 1:1 to 3:1; The ratio of the height of the second reaction zone (2) in the first direction to its diameter in the second direction is 1:1 to 3:1.

[0008] Optionally, the second reaction zone (2) includes: a main reaction zone (21) and a transition zone (22); The main reaction zone (21) and the transition zone (22) are connected in the first direction, and the main reaction zone (21) is located on the side of the transition zone (22) away from the first reaction zone; The air inlet of the transition zone (22) is connected to the air outlet (12) of the first reaction zone (1), and the air outlet of the transition zone (22) is connected to the interior of the main reaction zone (21). The diameter of the transition zone (22) in the second direction gradually decreases in the direction from the first reaction zone (1) to the main reaction zone (21).

[0009] Optionally, the diameter variation range of the transition zone (22) satisfies the following: the maximum diameter of the transition zone (22) in the second direction is the same as the diameter of the first reaction zone (1), and the minimum diameter of the transition zone (22) in the second direction is the same as the diameter of the main reaction zone (21).

[0010] Optionally, a porous distribution plate (13) is provided between the first reaction zone (1) and the second reaction zone (2). The porous distribution plate (13) is connected to the first reaction zone (1) and the second reaction zone (2) on opposite sides in the first direction. The porous distribution plate (13) includes a plurality of through holes, which serve as the air outlet (12) of the first reaction zone (1). The porous distribution plate (13) is configured to separate the first reaction zone (1) and the second reaction zone (2), and to allow the remaining synthesis gas and part of the catalyst in the first reaction zone (1) to enter the second reaction zone (2) to continue the synthesis of olefins.

[0011] Optionally, the second reaction zone (2) includes a main reaction zone (21) and a transition zone (22); the transition zone is located between the main reaction zone (21) and the first reaction zone (1); The porous distribution plate (13) includes a first porous distribution plate (131) disposed between the first reaction zone (1) and the transition zone (22), and a second porous distribution plate (132) disposed between the transition zone (22) and the main reaction zone (21).

[0012] Optionally, the opening ratio of the through holes on the porous distribution plate (13) is 3%-10%; The diameter of the air outlet (12) is 20mm-100mm; The porous distribution plate (13) has a size of 10mm-30mm in the first direction.

[0013] Optionally, the fluidized bed further includes: a heat exchange unit (3); The heat exchange unit (3) contains a cooling medium; The heat exchange unit (3) is connected to the interior of the first reaction zone (1); The heat exchange unit (3) is configured to exchange heat with the interior of the first reaction zone (1) using the cooling medium, thereby cooling the interior of the first reaction zone (1).

[0014] In a second aspect, embodiments of this application provide a method for preparing olefins from syngas, the method employing the variable-diameter fluidized bed method for preparing olefins from syngas described in the first aspect above, the method comprising: High-temperature gas is introduced into the first reaction zone (1) through the air inlet (11), and the high-temperature gas diffuses into the second reaction zone (2) through the air outlet (12) to heat the first reaction zone (1) and the second reaction zone (2). After heating, reducing gas is introduced into the first reaction zone (1) through the air inlet (11) to reduce the catalyst. Syngas is introduced into the first reaction zone (1) filled with the catalyst through the inlet (11). Under the action of the catalyst, the syngas undergoes a synthesis reaction to obtain gaseous products. The remaining synthesis gas and gaseous products in the first reaction zone (1) drive part of the catalyst into the second reaction zone (2) through the gas outlet (12), causing the remaining synthesis gas to continue to undergo olefin synthesis reaction in the second reaction zone (2) under the action of the catalyst, and obtain the gaseous products; the gaseous products include olefins.

[0015] Beneficial technical effects: In the embodiments of this application, the fluidized bed is divided into a first reaction zone and a second reaction zone connected vertically, with the diameter of the first reaction zone being larger than that of the second reaction zone, forming a variable-diameter fluidized bed. This structure can adapt to the characteristics of the syngas-to-olefins reaction, a molecular reduction reaction. Specifically, in the lower first reaction zone at the initial stage of the reaction, the syngas concentration is high and the reaction is vigorous. Using a larger diameter can maintain a suitable gas velocity, ensuring sufficient contact between the syngas and the catalyst and buffering the heat of reaction. When the syngas rises to the upper second reaction zone, the volumetric flow rate decreases due to the reduced number of gas molecules consumed in the reaction. The smaller cross-sectional area of ​​the second reaction zone allows the gas velocity to be maintained or even increased, thereby effectively avoiding the problem of poor gas-solid contact caused by the decrease in gas velocity in traditional constant-diameter reactors, and ensuring high utilization efficiency of the catalyst throughout the entire fluidized bed.

[0016] The fluidized bed structure provided in this application improves the single-pass conversion rate of syngas and the selectivity of target olefins by maintaining good gas-solid contact and fluidization throughout the reaction path, thereby reducing the amount of unreacted syngas recirculated. Simultaneously, the variable diameter arrangement within a single fluidized bed reactor achieves gradient optimization of reaction conditions, eliminating the need for complex external circulation or intermediate cooling systems required in traditional reactors to compensate for uneven syngas velocity, thus simplifying the process flow. These two factors combined reduce the energy consumption and costs of traditional separation and gas recirculation compression operations, enhancing the economics and feasibility of the process.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of a variable-diameter fluidized bed structure for syngas-to-olefins proposed in an embodiment of this application; Figure 2 This is a top view of the porous distribution plate proposed in the embodiments of this application; Figure 3 This is a schematic diagram of another variable-diameter fluidized bed structure for syngas-to-olefins proposed in the embodiments of this application; Figure 4 This is a flowchart of a method for preparing olefins from syngas according to an embodiment of this application.

[0019] Figure label: 1. First reaction zone; 11. Gas inlet; 12. Gas outlet; 13. Porous distribution plate; 131. First porous distribution plate; 132. Second porous distribution plate; 14. Catalyst inlet; 2. Second reaction zone; 21. Main reaction zone; 22. Transition zone; 23. Product outlet; 3. Heat exchange unit; 31. Cooling section; 32. Water inlet; 33. Water outlet; 4. Catalyst cooling unit; 41. Riser pipe; 42. Heat exchanger; 43. Gas flow inlet; 44. Circulation pipe; 5. Catalyst recovery unit. Detailed Implementation

[0020] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0022] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, 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, and therefore should not be construed as a limitation of this application.

[0023] 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. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] Among related technologies, syngas-to-olefins synthesis is a novel catalytic reaction route. Its advantages include a short process, low investment, wide applicability of raw materials, and low separation energy consumption. However, due to the late start of research in this field, there are still no mature and efficient fluidized bed reactors. For example, the fluidized bed structure is too simple to meet the required gas-solid contact conditions in the olefin synthesis process, resulting in low feed conversion rates, significant difficulties in subsequent gas separation, and high feed recycling costs.

[0025] Furthermore, the synthesis of olefins from syngas is a molecular weight reduction reaction. As the reaction conversion rate increases, the total number of moles of gas decreases, leading to a lower gas velocity above the catalyst and poor gas-solid contact. Simultaneously, the lower gas velocity reduces the mass transfer coefficient between the gas and the catalyst particle surface, making it more difficult for feed molecules to reach the active sites of the catalyst. This means that the outlet gas of the fluidized bed reactor contains some unreacted syngas, necessitating separation and recycling, thus increasing operating costs.

[0026] To overcome the shortcomings of related technologies, this application proposes a variable-diameter fluidized bed for syngas-to-olefins production, such as... Figure 1 As shown, it specifically includes: First reaction zone 1 and second reaction zone 2; The first reaction zone 1 has an air inlet 11 and an air outlet 12 at opposite ends in a first direction, with the air outlet 12 located above the air inlet 11; the air inlet 11 is used to introduce synthesis gas into the first reaction zone 1. The first reaction zone 1 is filled with a catalyst; The first reaction zone 1 and the second reaction zone 2 are connected in the first direction, and the second reaction zone 2 is located above the first reaction zone 1. The air outlet 12 is in communication with the interior of the second reaction zone 2. The diameter of the first reaction zone 1 in the second direction perpendicular to the first direction is greater than the diameter of the second reaction zone 2 in the second direction.

[0027] In some examples of this application, such as Figure 1 As shown, the axial cross-section of the first reaction zone 1 is rectangular; the first direction is... Figure 1 The OY direction (axial direction) is shown. In some examples of this application, the first reaction zone 1 constitutes the lower main body of the fluidized bed. Figure 1 The OX direction (radial) shown has a relatively large diameter, thus forming a reaction space with a large cross-section to provide sufficient flow cross-sectional area so that the catalyst can be fully fluidized and strong gas-solid contact can be achieved to initiate a high-speed reaction; An inlet 11 is provided at the bottom (or lower end) of the first reaction zone 1 in the axial direction for introducing synthesis gas into the first reaction zone 1; an outlet 12 is provided at the top (or upper end) of the first reaction zone 1 in the axial direction; the outlet 12 is a channel for the gas-solid mixture to enter the second reaction zone 2; the gas-solid mixture includes the remaining synthesis gas, gaseous products and part of the catalyst; the catalyst moves upward into the second reaction zone 2 under the carrying of the two gases; In some examples of this application, before the olefin synthesis reaction is carried out, high-temperature nitrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, so that the temperature of the first reaction zone 1 and the second reaction zone 2 in the fluidized bed reaches 400℃-420℃, which meets the temperature required for the reduction catalyst; the high-temperature nitrogen gas is finally discharged through the second reaction zone 2. In some examples of this application, such as Figure 1 As shown, a catalyst inlet 14 is provided on the first reaction zone 1 for filling the interior of the first reaction zone 1 with catalyst particles for syngas conversion. The catalyst inlet 14 is close to the gas outlet 12 of the first reaction zone 1; after the catalyst enters the fluidized bed from this position, it is more likely to enter the second reaction zone 2 above under the carrying effect of the rising gas flow. In practice, the highly active catalyst first contacts the syngas in the first reaction zone 1 to catalyze the synthesis of olefins; then, driven by the gas flow, it enters the second reaction zone 2 to continue catalyzing the remaining syngas. In some examples of this application, the main active phase of the catalyst is selected from one or more of iron carbide, cobalt carbide, and iron oxide; the promoter is one or more of oxides or carbonates or nitrates of potassium, sodium, calcium, magnesium, cerium, and titanium; and the support is carbon or molecular sieve. In some embodiments of this application, after the catalyst is introduced into the first reaction zone 1, the gas inlet 11 is also configured to introduce hydrogen into the first reaction zone 1 and reduce the catalyst for 0.3h-3h at 0.1MPa-1MPa to obtain the activated catalyst. In some examples of this application, the axial cross-section of the second reaction zone 2 is rectangular; the second direction is... Figure 1 The OX direction (radial) is shown. In the OY direction, the first reaction zone 1 and the second reaction zone 2 are connected in series along the coaxial axis, with the second reaction zone 2 located directly above the first reaction zone 1, forming a continuous reaction space. This structural arrangement is more in line with the characteristics of the natural upward flow of the mixture of syngas and other materials in a fluidized bed. The second reaction zone 2 constitutes the upper part of the fluidized bed. The radial diameter of the second reaction zone 2 is smaller than that of the first reaction zone 1 below it, thus forming a reaction space with a narrower cross-section relative to the first reaction zone 1. The small diameter of the second reaction zone 2 is an adaptation to the process of molecular reduction reaction. When gaseous products and syngas enter from the first reaction zone 1, the total number of moles of gas has decreased due to reaction consumption, and the volumetric flow rate has decreased accordingly. At this time, the smaller cross-sectional area allows the gas linear velocity to be maintained or even increased, thereby ensuring that even when the catalyst concentration is relatively low and the reaction driving force is reduced in the later stage of the reaction, a sufficiently strong gas-solid contact can still be maintained to promote the further conversion of the remaining syngas. In some examples of this application, such as Figure 1 As shown, the bottom of the second reaction zone 2 is connected to the air outlet 12 at the top of the first reaction zone 1 in the axial direction to receive the material conveyed from the first reaction zone 1. A product outlet 23 is opened at the top of the second reaction zone 2 in the axial direction. The product outlet 23 serves as the final outlet for the mixture after the reaction, and is used to discharge gaseous products and catalyst. In some examples of this application, such as Figure 1 As shown, the fluidized bed exhibits an overall convex or stepped cylindrical variable diameter structure with a thicker bottom and a thinner top in the axial direction. Inside the fluidized bed, the gas flow path is a unidirectional flow from bottom to top. Specifically, the synthesis gas enters from the large-diameter first reaction zone 1 at the bottom, passes through the first reaction zone 1 and the second reaction zone 2 in sequence, and is discharged from the top of the second reaction zone 2 at the top after completing the reaction. The catalyst particles are fluidized in the two zones under the drive of the gas, forming a continuous dynamic reaction system. In some examples of this application, the synthesis gas consists of CO and H2; the gaseous products mainly include olefins, as well as small amounts of other hydrocarbons.

[0028] In practice, a catalyst is pre-loaded inside the first reaction zone 1. The first reaction zone 1 and the second reaction zone 2 are heated to the temperature required for catalyst reduction. After the catalyst is reduced, the syngas is introduced into the first reaction zone 1 through the inlet 11. Under the action of the catalyst, an olefin synthesis reaction occurs to obtain gaseous products. During the process, part of the syngas and gaseous products carry part of the catalyst through the outlet 12 to the second reaction zone 2 to continue the olefin synthesis reaction, so that the syngas is converted into gaseous products. The obtained gaseous products and catalyst are discharged through the second reaction zone 2.

[0029] The embodiments of this application divide the fluidized bed into a first reaction zone 1 and a second reaction zone 2 connected vertically, with the diameter of the first reaction zone 1 being larger than that of the upper second reaction zone 2. This structure is adapted to the characteristics of the syngas-to-olefins reaction, a molecular reduction reaction. In the lower first reaction zone 1 at the initial stage of the reaction, the syngas concentration is high and the reaction is vigorous. The larger diameter of the second reaction zone 1 helps maintain a suitable gas velocity, ensuring sufficient contact between the syngas and the catalyst and buffering the heat of reaction. When the syngas rises to the upper second reaction zone 2, the volumetric flow rate decreases due to the reduced number of gas molecules consumed in the reaction. The smaller cross-sectional area of ​​the second reaction zone 2 allows the gas velocity to be maintained or even increased, effectively avoiding the gas-solid contact problem caused by the decrease in gas velocity in traditional constant-diameter reactors, and ensuring high utilization efficiency of the catalyst throughout the bed. Furthermore, the consumption of syngas by the second reaction zone 2 ensures that most of the syngas is converted, eliminating the need for subsequent separation and recycling steps, thereby reducing operating costs.

[0030] In the embodiments of this application, the CO conversion rate in the first reaction zone 1 is 60%-80%, and the CO conversion rate in the second reaction zone 2 is 15%-36%; the total CO conversion rate reaching the outlet of the second reaction zone 2 is 90%-96%, and the selectivity of the product C2-C6 olefins in hydrocarbons is 70%-90%.

[0031] In some examples of this application, such as Figure 1 As shown, the diameter of the first reaction zone 1 in the second direction is 1.5-3 times the diameter of the second reaction zone 2 in the second direction.

[0032] It should be noted that the second direction is Figure 1 The OX direction (radial) is shown. For example, the radial diameter of the first reaction zone 1 is 1.5 times, 2 times, 2.5 times, and 3 times the radial diameter of the second reaction zone 2; this diameter ratio indicates that the radial cross-sectional area of ​​the second reaction zone 2 is reduced to approximately 1 / 2.25 to 1 / 9 of that of the first reaction zone 1. This arrangement allows the syngas to enter the smaller diameter zone of the second reaction zone 2 from the larger diameter zone of the first reaction zone 1, so that even if the gas volume flow rate has decreased significantly due to reaction consumption, its linear velocity can be effectively maintained or even increased due to the contraction of the flow cross-section, thereby solving the problems of decreased gas velocity and poor gas-solid contact in the later stages of conventional constant-diameter reactors.

[0033] In some examples of this application, such as Figure 1 As shown, the ratio of the height of the first reaction zone 1 in the first direction to its diameter in the second direction is 1:1 to 3:1; The ratio of the height of the second reaction zone 2 in the first direction to its diameter in the second direction is 1:1 to 3:1.

[0034] It should be noted that the height of the first reaction zone 1 in the first direction is... Figure 1 The vertical distance of the first reaction zone 1 in the axial direction is shown; for example, the ratio of the height of the first reaction zone 1 in the axial direction to its diameter in the radial direction is 1:1, 1.5:1, 2:1, 2.5:1, or 3:1. The height of the second reaction zone 2 in the first direction is: Figure 1 The vertical distance of the second reaction zone 2 in the axial direction is shown; for example, the ratio of the height of the second reaction zone 2 in the axial direction to its diameter in the radial direction is 1:1, 1.5:1, 2:1, 2.5:1, or 3:1; the embodiments of this application limit the height-to-diameter ratio of the first reaction zone 1 and the second reaction zone 2, so that the fluidized bed structure is more adaptable to changes in gas flow rate, so that each reaction zone has an axial space that matches its function, and so that the gas has a reasonable residence time in the reaction zone of a specific diameter.

[0035] In some examples of this application, such as Figure 1 As shown, a porous distribution plate 13 is provided between the first reaction zone 1 and the second reaction zone 2; The porous distribution plate 13 is connected to the first reaction zone 1 and the second reaction zone 2 on opposite sides in the first direction, and the porous distribution plate 13 includes a plurality of through holes, which serve as the air outlet 12 of the first reaction zone 1. The porous distribution plate 13 is configured to separate the first reaction zone 1 and the second reaction zone 2, and to allow the remaining synthesis gas and part of the catalyst in the first reaction zone 1 to enter the second reaction zone 2 to continue the synthesis of olefins.

[0036] It should be noted that the porous distribution plate 13 is in Figure 1 The shown is horizontally positioned in the OX direction between the first reaction zone 1 and the second reaction zone 2; The porous distribution plate 13 is connected to the top of the first reaction zone 1 on the side facing the first reaction zone 1, and connected to the bottom of the second reaction zone 2 on the side away from the first reaction zone 1. In some examples of this application, multiple through holes on the porous distribution plate 13 are arranged uniformly in the radial direction, and the multiple through holes together constitute the gas outlet 12 of the first reaction zone 1. In some examples of this application, the through hole may be inverted tapered; such as Figure 1As shown, the axial diameter of the through-hole can gradually increase from the first reaction zone to the second reaction zone; the relatively small inlet diameter exerts a certain constraint and acceleration effect on the gas-solid mixture transported in the first reaction zone 1, which helps to break up large bubbles and prevent catalyst from depositing under the plate; as the gas flow moves upward in the channel, the gradually increasing diameter allows the flow velocity to decrease gradually and the pressure to partially recover, so that it enters the second reaction zone 2 in a more uniform and dispersed state, while also reducing the occurrence of gas backmixing; In some examples of this application, a micro pneumatic cleaning structure can be provided at the through hole; for example, an annular slit or a series of micro nozzles surrounding the through hole wall; using the directional pulse jet of the clean air source to peel off and remove the deposits in the through hole channel, solving the problem of through hole blockage caused by catalyst dust accumulation or coking in the porous distribution plate 13 during long-term operation. In some examples of this application, the porous distribution plate 13 may be made of a special alloy or ceramic composite material that is resistant to high temperature and corrosion, giving it excellent mechanical strength and thermal stability. In some examples of this application, the surface of the porous distribution plate 13 may be coated with a catalytically inert coating to reduce side reactions; In some examples of this application, the through-hole also allows the gaseous products synthesized in the first reaction zone 1 to pass through, so that they enter the second reaction zone 2 and are discharged together with the newly synthesized gaseous products.

[0037] This embodiment of the application achieves effective physical separation of the first reaction zone 1 and the second reaction zone 2 by setting a porous distribution plate 13, and reduces the degree of gas backmixing. Compared with the structure of traditional reactors without a distribution plate and without two reaction zones, the CO conversion rate can be increased by 10%-15%.

[0038] In some examples of this application, such as Figure 2 As shown, the porosity of the through holes on the porous distribution plate 13 is 3%-10%; for example, the porosity of the through holes on the porous distribution plate 13 is 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%. The porosity of the porous distribution plate 13 is in the range of 3%-10%, which can regulate the transmission force between the gas and solid phases in the first reaction zone 1 and the second reaction zone 2, and can generate suitable local resistance. On the one hand, it is sufficient to maintain a sufficiently high catalyst content and reaction intensity in the lower part of the first reaction zone 1, providing a stable reaction environment for primary conversion; on the other hand, it allows the gas after reaction and an appropriate amount of catalyst to pass through uniformly at a controllable rate, continuously transporting reactants and replenishing active catalyst in the upper second reaction zone 2, ensuring the material basis required for deep conversion of syngas.

[0039] like Figure 2 As shown, the diameter of the air outlet 12 is 20mm-100mm; It should be noted that the diameter of the outlet 12 is the same as the diameter of each through hole on the porous distribution plate 13; for example, the diameter of the outlet 12 is 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, or 100mm; limiting the diameter of the outlet 12 to the range of 20mm-100mm allows the gas flow from the first reaction zone 1 into the second reaction zone 2 to carry an appropriate amount of catalyst to form a stable and uniform jet, and to quickly achieve efficient redistribution and full fluidization of gas and catalyst in the small diameter space of the second reaction zone 2.

[0040] The porous distribution plate 13 has a dimension of 10mm-30mm in the first direction; like Figure 1 As shown, the dimension of the porous distribution plate 13 in the first direction is the thickness of the porous distribution plate 13 in the axial direction; for example, the dimension of the porous distribution plate 13 in the first direction is 10mm, 15mm, 20mm, 25mm, or 30mm; limiting the thickness of the porous distribution plate 13 to the range of 10mm-30mm ensures that it has certain structural rigidity, fluid flow characteristics, and thermal stability, and has sufficient mechanical strength to withstand the gas-solid erosion, thermal stress, and pressure difference between the first reaction zone 1 and the second reaction zone 2 inside the fluidized bed, preventing deformation or damage, and ensuring the physical integrity and safety of the fluidized bed during long-term operation.

[0041] In some examples of this application, such as Figure 3 As shown, the second reaction zone 2 includes: a main reaction zone 21 and a transition zone 22; The main reaction zone 21 and the transition zone 22 are connected in the first direction, and the main reaction zone 21 is located on the side of the transition zone 22 away from the first reaction zone 1. The air inlet of the transition zone 22 is connected to the air outlet 12 of the first reaction zone 1, and the air outlet of the transition zone 22 is connected to the interior of the main reaction zone 21. The diameter of the transition zone 22 in the second direction gradually decreases towards the direction from the first reaction zone 1 to the main reaction zone 21.

[0042] It should be noted that, as Figure 3 As shown, the bottom end of the transition zone 22 in the axial direction is connected to the top end of the first reaction zone 1, and the top end of the transition zone 22 in the axial direction is connected to the bottom end of the main reaction zone 21. In some examples of this application, the bottom end of the transition zone 22 is connected to the side of the porous distribution plate 13 away from the first reaction zone 1, and the through holes on the porous distribution plate 13 are connected to the interior of the transition zone 22. In some examples of this application, the axial profile of the transition region 22 is conical, such as conical or arc transition, so that its cross-sectional area continuously contracts from bottom to top in the axial direction; In some examples of this application, after the gas-solid mixture in the first reaction zone 1 enters the transition zone 22 through the through holes on the porous distribution plate 13, its linear velocity will be gradually increased as the flow cross section of the transition zone 22 shrinks, and the flow state will be reorganized and homogenized. In some examples of this application, the main reaction zone 21 is located directly above the transition zone 22 in the axial direction and is the main body of the second reaction zone 2; the main reaction zone 21 has a cylindrical structure. Product outlet 23 is located at the top of main reaction zone 21; In some examples of this application, the main reaction zone 21 is used to receive the accelerated and homogenized gas-solid stream from the transition zone 22 and to provide a stable reaction space for the deep conversion of the remaining syngas; In some examples of this application, combined with the first reaction zone 1, the entire fluidized bed forms a composite variable diameter fluidized bed structure of "large diameter cylinder (first reaction zone 1) → contraction transition section (transition zone 22) → small diameter cylinder (main reaction zone 21)", and the flow path is a unidirectional series from bottom to top.

[0043] This embodiment of the application adds a transition zone 22 with a gradually decreasing diameter between the main reaction zone 21 and the first reaction zone 1, achieving a smoother and more efficient flow field reconstruction for the gas-solid two-phase flow entering the main reaction zone 21 from the first reaction zone 1. The conical contraction structure of the transition zone 22 provides a gradual acceleration and guidance effect on the airflow, enabling the gas and carried catalyst particles to smoothly transition from a large space to a small space. This acceleration process can maintain and increase the gas velocity in the later stages of the reaction, strengthening the gas-solid contact intensity to promote deep conversion.

[0044] In some examples of this application, such as Figure 3 As shown, the diameter variation range of the transition zone 22 satisfies the following: the maximum diameter of the transition zone 22 in the second direction is the same as the diameter of the first reaction zone 1, and the minimum diameter of the transition zone 22 in the second direction is the same as the diameter of the main reaction zone 21.

[0045] It should be noted that the diameter of the first reaction zone 1 is the same at any position in the axial direction; the diameter of the main reaction zone 21 is the same at any position in the axial direction. In some examples of this application, the maximum diameter of the transition zone 22 is located at its air inlet end, that is, the end connected to the first reaction zone 1; looking upward from the first reaction zone 1, the diameter of the top porous distribution plate 13 plane is completely consistent with and flush with the diameter of the air inlet side of the transition zone 22, and there is no sudden expansion or contraction of any section at the connection. In some examples of this application, the minimum diameter of the transition zone 22 is located at its outlet end, that is, the end connected to the main reaction zone 21, to ensure that the top outlet of the transition zone 22 and the bottom inlet of the main reaction zone 21 are perfectly matched in diameter and smoothly connected. In some examples of this application, the geometry of the transition region 22 is a regular contraction space in which the diameter continuously and uniformly contracts from the maximum value at the bottom to the minimum value at the top; In this embodiment, by limiting the diameter of the transition zone 22 to be the same as that of the adjacent first reaction zone 1 and main reaction zone 21, the smooth continuity and seamless connection of the internal flow channel geometry of the fluidized bed are achieved. This guides the gas-solid two-phase flow to complete the transition from a large-diameter environment to a small-diameter environment smoothly, orderly and efficiently, and provides uniform and stable axial feed to the main reaction zone 21.

[0046] In some examples of this application, such as Figure 3 As shown, the diameter of the transition zone 22 changes linearly in the direction from the first reaction zone 1 toward the main reaction zone 21; the outline of the inner wall of the transition zone 22 appears as a straight line in the longitudinal section along the axial direction. In some examples of this application, the diameter (D) of the transition zone 22 varies with the axial height (H) according to the linear relationship D(H) = D1 - kH, where D1 is the bottom diameter and k is a constant slope. In three-dimensional space, this structure forms a frustum or truncated cone cavity, the sidewall of which is a conical surface formed by rotating a straight generatrix around the central axis. This makes the entire transition zone 22 a regular, uniform, and non-abrupt conical connecting section from a large diameter to a small diameter. When the gas flows through this region, its flow area shrinks in a deterministic and continuously differentiable manner. The flow paths of the gas and catalyst are continuous at the diameter change points, without any sudden turns or abrupt changes in cross-section caused by size mismatch. This achieves a smoother flow field reconstruction and velocity enhancement with minimal disturbance, providing more uniform gas intake conditions for the main reaction zone 21.

[0047] In some examples of this application, such as Figure 3 As shown, the axial height of the transition zone 22 is 0.2-1 times that of the main reaction zone 21. For example, the axial height of the transition zone 22 is 0.2, 0.4, 0.6, 0.8, 0.9, and 1 times that of the main reaction zone 21. The limitation of the axial height of the transition zone 22 provides sufficient longitudinal space to guide the gas-solid flow to complete a smooth and gradual transition from the large-diameter first reaction zone 1 to the small-diameter main reaction zone 21. Its conical structure can fully mitigate the abrupt flow changes caused by the cross-sectional change, achieve a uniform increase in flow velocity and an ideal distribution of materials, and provide uniform and stable feeding conditions for the upper main reaction zone 21.

[0048] In some examples of this application, such as Figure 3 As shown, the second reaction zone 2 includes a main reaction zone 21 and a transition zone 22; the transition zone 22 is located between the main reaction zone 21 and the first reaction zone 1. The porous distribution plate 13 includes a first porous distribution plate 131 disposed between the first reaction zone 1 and the transition zone 22, and a second porous distribution plate 132 disposed between the transition zone 22 and the main reaction zone 21.

[0049] It should be noted that, in cases such as Figure 3 In the OY direction shown, the first porous distribution plate 131 is horizontally connected to the top of the first reaction zone 1 and the bottom of the transition zone 22, respectively, and the second porous distribution plate 132 is horizontally connected to the top of the transition zone 22 and the bottom of the main reaction zone 21, respectively. like Figure 3 As shown, the first porous distribution plate 131 is provided with multiple through holes, which serve as the air outlet 12 of the first reaction zone 1; the second porous distribution plate 132 is also provided with multiple through holes, which are used to connect the transition zone 22 and the main reaction zone 21. In some examples of this application, the porous distribution plate 13 is sealed to the inner wall of the fluidized bed, dividing the entire fluidized bed into three continuous spaces from bottom to top. The syngas must pass through the first porous distribution plate 131 and the second porous distribution plate 132 in sequence to complete the entire process from feed to discharge. In this embodiment, by adding a second porous distribution plate 132, the operating gas velocity, catalyst quantity and residence time of the first reaction zone 1, the transition zone 22 and the main reaction zone 21 can be independently optimized, forming a progressively optimized reaction sequence, which is beneficial for controlling the temperature distribution of the strongly exothermic reaction and suppressing the series side reactions.

[0050] In some examples of this application, such as Figure 3 As shown, the fluidized bed further includes: a heat exchange unit 3; The heat exchange unit 3 contains a cooling medium; The heat exchange unit 3 is connected to the interior of the first reaction zone 1; The heat exchange unit 3 is configured to exchange heat with the interior of the first reaction zone 1 using the cooling medium, thereby cooling the interior of the first reaction zone 1.

[0051] It should be noted that the heat exchange unit 3 is an independent cold zone device. The heat exchange part of the heat exchange unit 3 is connected to the interior of the first reaction zone 1 so that the cooling medium can enter the first reaction zone 1 and exchange heat with its interior, thereby cooling the first reaction zone 1 and maintaining the temperature of the first reaction zone 1 at 250℃-350℃ and the pressure at 2MPa-5MPa. The cooling medium is selected from one or more of cooling water, heat transfer oil, and molten salt.

[0052] The heat exchange unit 3 is provided in this embodiment because the synthesis of olefins from syngas is a strongly exothermic reaction. The heat exchange unit 3 can remove a large amount of reaction heat inside the first reaction zone 1 in a timely manner, thereby suppressing side reactions such as catalyst sintering, coking and deactivation, and excessive hydrogenation of olefin products caused by excessively rapid temperature rise or local overheating in the first reaction zone 1.

[0053] In some examples of this application, such as Figure 3 As shown, the heat exchange unit 3 includes a cooling section 31, and an inlet 32 ​​and an outlet 33 connected to the cooling section 31. The cooling section 31 is located inside the first reaction zone 1. The inlet 32 ​​and outlet 33 are connected to the two ends of the cooling section 31 through water pipes, and both the inlet 32 ​​and outlet 33 are located outside the first reaction zone 1. like Figure 3 As shown, the inlet 32 ​​can be located above the outlet 33, or the outlet 33 can be located above the inlet 32, or the inlet 32 ​​and the outlet 33 can be arranged parallel to each other in the radial direction. The cooling water introduced into heat exchange unit 3 is saturated water at 150℃-280℃.

[0054] In practice, cooling medium is supplied to cooling section 31 through inlet 32. The cooling medium exchanges heat with the interior of first reaction zone 1 in a non-contact manner, thereby cooling the interior of first reaction zone 1. The heated cooling medium is discharged through outlet 33, and new cooling medium enters through inlet 32, thus circulating and cooling first reaction zone 1.

[0055] In some examples of this application, the CO conversion rate of the variable diameter fluidized bed is 90%-98%, while the CO conversion rate of the traditional monolithic reactor with the same top and bottom diameters can only reach 80%-83%. Based on the manufacturing cost of 100% of the variable diameter fluidized bed in the embodiments of this application, the manufacturing cost of a reactor of the same diameter under the same conditions reaches 115%-120%.

[0056] In some examples of this application, such as Figure 3 As shown, the fluidized bed also includes a catalyst cooling unit 4; Catalyst cooling unit 4 includes riser 41 and heat exchanger 42; The feed end of the riser pipe 41 is connected to the interior of the second reaction zone 2; specifically, the feed end of the riser pipe 41 is connected to the interior of the main reaction zone 21 of the second reaction zone 2; the discharge end of the riser pipe 41 is connected to the interior of the heat exchanger 42. The outlet end of the heat exchanger 42 is connected to the interior of the second reaction zone 2; specifically, the outlet end of the heat exchanger 42 is connected to a circulation pipe 44; the end of the circulation pipe 44 away from the heat exchanger 42 is connected to the interior of the transition zone 22 of the second reaction zone 2. In practice, when the temperature of the second reaction zone 2 continues to rise, some of the high-temperature catalyst in the second reaction zone 2 can be removed through the riser pipe 41 to reduce the temperature of the second reaction zone 2. The removed high-temperature catalyst is cooled in the heat exchanger 42 and then returned to the transition zone 22 of the second reaction zone 2. Under the influence of airflow, it enters the main reaction zone 21 to continue participating in the reaction. At the same time, after the low-temperature catalyst enters the second reaction zone 2, it can also cool the interior of the second reaction zone 2 a second time, further maintaining the temperature of the second reaction zone 2 at 270℃-350℃.

[0057] This embodiment of the application achieves a faster catalyst cooling effect by setting up a catalyst cooling unit 4 (external heat exchange) and using a lower-temperature cooling medium. While ensuring that the heat exchange unit 3 (internal heat exchange) obtains a large amount of high-temperature steam with high saturation pressure, compared with the structure of placing all heat exchange tubes in the fluidized bed, the manufacturing cost can be reduced by 10%-20%, the maintenance cost by 30%-60%, and the difficulty of equipment scale-up is reduced by 20%-40%.

[0058] In some embodiments of this application, cooling water flows through the heat exchanger 42 of the catalyst cooling unit 4, and the cooling water exchanges heat with the catalyst to cool it down; wherein, the temperature of the cooling water is 50°C-150°C lower than the temperature of the cooling medium in the heat exchange unit 3; for example, the temperature of the cooling water is 0°C-150°C.

[0059] In some examples of this application, the heat of reaction removed by the catalyst cooling unit 4 is 0.1-0.5 times the heat of reaction removed by the heat exchange unit 3; this is because only a portion of the syngas in the second reaction zone 2 is deeply converted, and the amount of synthesis is much lower than that in the first reaction zone 1, so its heat release is lower than that in the first reaction zone 1, and the heat removed is also lower than that in the first reaction zone 1.

[0060] In some examples of this application, such as Figure 3 As shown, a gas flow inlet 43 is provided on the riser tube 41 near the second reaction zone 2; the gas flow inlet 43 is used to introduce riser gas into the riser tube 41; by changing the gas velocity of the riser gas, the flow rate of the catalyst in the riser tube 41 can be changed. The boosting gas is selected from one or more of syngas, methane, and CO2, and the gas velocity of the boosting gas is 3m / s-8m / s; for example, 3m / s, 4m / s, 5m / s, 6m / s, 7m / s, 8m / s; the boosting gas in the riser pipe 41 can be directly discharged through the outlet of the heat exchanger 42; In the main reaction zone 21 of the second reaction zone 2, a small amount of syngas and / or gaseous products are discharged through the riser 41 and then enter the heat exchanger 42, and are finally discharged through the heat exchanger 42.

[0061] In some examples of this application, such as Figure 3 As shown, the fluidized bed also includes a catalyst recovery unit 5; It should be noted that the feed end of the catalyst recovery unit 5 is connected to the interior of the second reaction zone 2; specifically, the feed end of the catalyst recovery unit 5 is connected to the product outlet 23 at the top of the main reaction zone 21 of the second reaction zone 2. The discharge end of the catalyst recovery unit 5 is connected to the inlet of the catalyst cooling unit 4; The catalyst recovery unit 5 is used to separate the gaseous products and catalyst discharged from the second reaction zone 2; wherein, the separated gaseous products are discharged directly, and the catalyst is transported to the catalyst cooling unit 4 for cooling and recovery; the recovered catalyst is cooled and then transported to the transition zone 22 for recycling.

[0062] In some examples of this application, the mass of catalyst moved by the riser 41 is 0.3 to 3 times the mass of catalyst recovered by the catalyst recovery unit 5; in specific implementation, the mass of catalyst lifted by the riser 41 can be adjusted according to the temperature inside the second reaction zone 2 to maintain the temperature of the second reaction zone 2 at 270°C-350°C.

[0063] In some examples of this application, taking the preparation cost of the variable diameter fluidized bed with the catalyst recovery unit 5 set externally in the embodiment of this application as 100% as a benchmark, under the same conditions, the manufacturing cost of the conventional catalyst recovery device set inside the fluidized bed reaches 110%-120%; In some examples of this application, taking the preparation cost of the variable-diameter fluidized bed with internal heat exchange unit 3 and external catalyst cooling unit 4 as 100% as a benchmark, under the same conditions, if both heat exchange unit 3 and catalyst cooling unit 4 are set inside the reactor, the preparation cost reaches 110%-120%; taking the maintenance cost of the variable-diameter fluidized bed in the embodiment of this application as 100% as a benchmark, the maintenance cost of the traditional reactor reaches 130%-160%; taking the scale-up difficulty of the variable-diameter fluidized bed equipment in the embodiment of the application as a benchmark, the maintenance cost of the traditional reactor reaches 120%-140%.

[0064] This application also provides a method for preparing olefins from syngas, the method employing... Figure 1 The variable-diameter fluidized bed for syngas-to-olefins process shown is as follows: Figure 4 As shown, it specifically includes: Step S1: A high-temperature gas source is introduced into the first reaction zone 1 through the air inlet 11. The high-temperature gas source diffuses to the second reaction zone 2 through the air outlet 12 to heat the first reaction zone 1 and the second reaction zone 2. After heating, reducing gas is introduced into the first reaction zone 1 through the air inlet 11 to reduce the catalyst. Step S2: Syngas is introduced into the first reaction zone 1 filled with the catalyst through the gas inlet 11. Under the action of the reduced catalyst, the syngas undergoes a synthesis reaction to obtain gaseous products. Step S3: The remaining synthesis gas and gaseous products in the first reaction zone 1 carry part of the catalyst into the second reaction zone 2 through the gas outlet 12, causing the remaining synthesis gas to continue to undergo olefin synthesis reaction in the second reaction zone 2 under the action of the catalyst, and obtain the gaseous products; the gaseous products include olefins.

[0065] It should be noted that the high-temperature gas source includes nitrogen; the high-temperature gas source heats the temperature inside the first reaction zone 1 and the second reaction zone 2 to 400℃-420℃; The reducing gas includes hydrogen; the reduction process needs to be carried out at a pressure of 0.1 MPa-1 MPa; the reduction process time is 0.3 h-3 h. After the reduction process is completed, the synthesis gas is introduced into the first reaction zone 1 through the gas inlet 11; Gaseous products include olefins and other hydrocarbon products.

[0066] The method for preparing olefins from syngas provided in this application embodiment relies on... Figure 1 or Figure 3 The variable-diameter fluidized bed structure shown is implemented. This method continuously completes the preheating of the fluidized bed, catalyst reduction and activation, and olefin synthesis reaction within the same variable-diameter fluidized bed, realizing in-situ start-up of the equipment and online activation of the catalyst, simplifying the process. In the olefin synthesis reaction stage, through the first reaction zone 1 and the second reaction zone 2, the reactants and catalyst are automatically distributed and circulated between the two reaction zones by relying on the natural flow of the gas-solid mixture. The first reaction zone 1 mainly carries out the main reaction at high concentrations, while the second reaction zone 2 uses its optimized flow field to deeply convert the remaining raw materials. The synergistic effect of the two significantly improves the single-pass conversion rate and olefin selectivity, reduces the circulation ratio of unreacted syngas, simplifies the start-up procedure, and ensures catalyst activity, thereby reducing overall energy consumption and operating costs.

[0067] To enable those skilled in the art to better understand this application, the following embodiments are provided to illustrate in detail a variable-diameter fluidized bed and method for preparing olefins from syngas.

[0068] Example 1 use Figure 1 The illustrated variable-diameter fluidized bed structure for syngas-to-olefins production shows that the diameter of the first reaction zone 1 is twice the diameter of the main reaction zone 21, the height-to-diameter ratio of the first reaction zone 1 is 3:1, and the overall height-to-diameter ratio of the second reaction zone 2 is 1:1. The specific steps include: (1) A catalyst (the active phase of the catalyst is iron carbide, the additives are sodium carbonate and cerium carbonate, and the support is carbon) is loaded into the first reaction zone 1. High-temperature nitrogen gas is introduced into the first reaction zone 1 through the gas inlet 11. The high-temperature nitrogen gas diffuses into the second reaction zone 2 through the gas outlet 12, heating the entire fluidized bed to 414°C. (2) After heating, hydrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, and the catalyst is reduced for 0.3 h at 1 MPa; the hydrogen gas and high-temperature nitrogen gas are discharged through the second reaction zone 2. (3) After the catalyst reduction is completed, stop the flow of high temperature nitrogen and hydrogen, and introduce room temperature synthesis gas (CO+H2) into the first reaction zone 1 through the gas inlet 11. Gradually increase the flow rate of synthesis gas so that the heat of reaction is used to heat the synthesis gas first, and stabilize the temperature of the first reaction zone 1 at 350℃ and the pressure at 2MPa. (4) Due to the increase in the flow rate of the syngas, the gas velocity in the first reaction zone 1 increases, carrying some of the catalyst and entering the second reaction zone 2 through the gas outlet 12. The overall temperature of the second reaction zone 2 is controlled at 270℃-300℃. The remaining syngas continues to undergo deep conversion in the main reaction zone 21 under the action of the catalyst to obtain gaseous products. The gaseous products and catalyst are discharged through the second reaction zone 2.

[0069] It should be noted that, according to the test results, in Example 1, the CO conversion rate in the first reaction zone 1 was 80%, and the CO conversion rate in the main reaction zone 21 of the second reaction zone 2 was 15%. The total CO conversion rate at the product outlet 23 reaching the main reaction zone 21 was 95%, and the selectivity of C2-C6 olefins in hydrocarbons was 78%.

[0070] Example 2 use Figure 3 The illustrated variable-diameter fluidized bed structure for syngas-to-olefins production includes a first reaction zone 1 with a diameter twice that of the main reaction zone 21, a height-to-diameter ratio of 3:1, and a second reaction zone 2 with an overall height-to-diameter ratio of 1:1. The height of the transition zone 22 is 0.2 times that of the main reaction zone 21. The porous distribution plate 13 has a porosity of 6%, a pore size of 3 mm, and a thickness of 10 mm. The specific steps include: (1) A catalyst (the active phase of the catalyst is iron carbide, the additives are sodium carbonate and cerium carbonate, and the support is carbon) is loaded into the transition zone 22 from the catalyst inlet 14. High-temperature nitrogen gas is introduced into the first reaction zone 1 from the gas inlet 11. The high-temperature nitrogen gas diffuses into the second reaction zone 2 through the through holes on the porous distribution plate 13, heating the entire fluidized bed to 414°C. (2) After heating, hydrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, and the catalyst is reduced for 0.3 h at 1 MPa; the hydrogen gas and high temperature nitrogen gas are discharged through the product outlet 23 of the main reaction zone 21. (3) After the catalyst reduction is completed, stop the flow of high temperature nitrogen and hydrogen, and introduce room temperature synthesis gas (CO+H2) into the first reaction zone 1 through the gas inlet 11. Gradually increase the flow rate of synthesis gas so that the heat of reaction is used to heat the synthesis gas first, and stabilize the temperature of the first reaction zone 1 at 350℃ and the pressure at 2MPa. (4) If the temperature of the first reaction zone 1 continues to rise, cooling water (saturated water at 200℃-250℃) is introduced into the heat exchange unit 3 to lower the temperature in the first reaction zone 1. (5) Due to the increase in the syngas flow rate, the gas velocity in the first reaction zone 1 increases, carrying some of the catalyst. It diffuses through the through holes on the first porous distribution plate 131 to the transition zone 22, and then enters the main reaction zone 21 of the second reaction zone 2 through the second porous distribution plate 132, controlling the overall temperature of the second reaction zone 2 at 270-300℃. The remaining syngas continues to undergo deep conversion in the main reaction zone 21 under the action of the catalyst to obtain gaseous products. The gaseous products and catalyst are discharged through the product outlet 23 on the main reaction zone 21.

[0071] It should be noted that, according to testing, in Example 2, the CO conversion rate in the first reaction zone 1 was 80%, and the CO conversion rate in the main reaction zone 21 of the second reaction zone 2 was 15%. The total CO conversion rate at the product outlet 23 reaching the main reaction zone 21 was 95%, and the selectivity of C2-C6 olefins in hydrocarbons was 78%.

[0072] Example 3 use Figure 3 The illustrated variable-diameter fluidized bed structure for syngas-to-olefins production includes a first reaction zone 1 with a diameter twice that of the main reaction zone 21, a height-to-diameter ratio of 3:1, and a second reaction zone 2 with an overall height-to-diameter ratio of 1:1. The height of the transition zone 22 is 0.2 times that of the main reaction zone 21. The porous distribution plate 13 has a porosity of 6%, a pore size of 3 mm, and a thickness of 10 mm. The specific steps include: (1) A catalyst (the active phase of the catalyst is iron carbide, the additives are sodium carbonate and cerium carbonate, and the support is carbon) is loaded into the transition zone 22 from the catalyst inlet 14. High-temperature nitrogen gas is introduced into the first reaction zone 1 from the gas inlet 11. The high-temperature nitrogen gas diffuses into the second reaction zone 2 through the through holes on the porous distribution plate 13, heating the entire fluidized bed to 414°C. (2) After heating, hydrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, and the catalyst is reduced for 0.3 h at 1 MPa; the hydrogen gas and high temperature nitrogen gas are discharged through the product outlet 23 of the main reaction zone 21. (3) After the catalyst reduction is completed, stop the flow of high temperature nitrogen and hydrogen, and introduce room temperature synthesis gas (CO+H2) into the first reaction zone 1 through the gas inlet 11. Gradually increase the flow rate of synthesis gas so that the heat of reaction is used to heat the synthesis gas first, and stabilize the temperature of the first reaction zone 1 at 350℃ and the pressure at 2MPa. (4) If the temperature of the first reaction zone 1 continues to rise, cooling water (saturated water at 200℃-250℃) is introduced into the heat exchange unit 3 to lower the temperature in the first reaction zone 1. (5) Due to the increase in the syngas flow rate, the gas velocity in the first reaction zone 1 increases, carrying some of the catalyst. It diffuses through the through holes on the first porous distribution plate 131 to the transition zone 22, and then enters the main reaction zone 21 of the second reaction zone 2 through the second porous distribution plate 132, controlling the overall temperature of the second reaction zone 2 at 270-300℃. The remaining syngas continues to undergo deep conversion in the main reaction zone 21 under the action of the catalyst to obtain gaseous products. The gaseous products and catalyst are discharged through the product outlet 23 on the main reaction zone 21. (6) The gaseous products and catalyst discharged from the product outlet 23 of the main reaction zone 21 enter the catalyst recovery unit 5 for separation. The gaseous products are discharged through the outlet of the catalyst recovery device and then enter the subsequent processing section. The catalyst enters the heat exchanger 42 for cooling and then returns to the transition zone 22 for recycling through the circulation pipe 44. (7) When the second reaction continues to heat up, a portion of the catalyst is taken out through the riser pipe 41, and the velocity of the riser gas (syngas) at the gas inlet 43 is controlled to be 8 m / s, thereby changing the mass of the catalyst carried out; the catalyst is taken into the heat exchanger 42 for heat exchange and cooling (the temperature of the cooling water is 120℃-150℃); the riser gas is discharged from the outlet of the heat exchanger 42, and the catalyst is returned to the transition zone 22 for recycling through the circulation pipe 44.

[0073] It should be noted that, according to testing, in Example 3, the CO conversion rate in the first reaction zone 1 was 80%, and the CO conversion rate in the main reaction zone 21 of the second reaction zone 2 was 15%. The total CO conversion rate at the product outlet 23 reaching the main reaction zone 21 was 95%, and the selectivity of C2-C6 olefins in hydrocarbons was 78%.

[0074] Example 4 use Figure 3 The illustrated variable-diameter fluidized bed structure for syngas-to-olefins production includes a first reaction zone 1 with a diameter three times that of the main reaction zone 21, a height-to-diameter ratio of 1:1, and a second reaction zone 2 with an overall height-to-diameter ratio of 3:1. The height of the transition zone 22 is one time the height of the main reaction zone 21. The porous distribution plate 13 has a porosity of 25%, a pore size of 10 mm, and a thickness of 30 mm. The specific steps include: (1) A catalyst (the active phase of the catalyst is iron carbide, the additives are sodium carbonate and cerium carbonate, and the support is carbon) is loaded into the transition zone 22 from the catalyst inlet 14. High-temperature nitrogen gas is introduced into the first reaction zone 1 from the gas inlet 11. The high-temperature nitrogen gas diffuses into the second reaction zone 2 through the through holes on the porous distribution plate 13, heating the entire fluidized bed to 410°C. (2) After heating, hydrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, and the catalyst is reduced for 1 hour at 0.5 MPa; the hydrogen gas and high-temperature nitrogen gas are discharged through the product outlet 23 of the main reaction zone 21. (3) After the catalyst reduction is completed, stop the flow of high temperature nitrogen and hydrogen, and introduce room temperature synthesis gas (CO+H2) into the first reaction zone 1 through the gas inlet 11. Gradually increase the flow rate of synthesis gas so that the heat of reaction is used to heat the synthesis gas first, and stabilize the temperature of the first reaction zone 1 at 340℃ and the pressure at 4MPa. (4) If the temperature of the first reaction zone 1 continues to rise, cooling water (saturated water at 250℃-280℃) is introduced into the heat exchange unit 3 to lower the temperature in the first reaction zone 1. (5) Due to the increase in the syngas flow rate, the gas velocity in the first reaction zone 1 increases, carrying some of the catalyst. It diffuses through the through holes on the first porous distribution plate 131 to the transition zone 22, and then enters the main reaction zone 21 of the second reaction zone 2 through the second porous distribution plate 132, controlling the overall temperature of the second reaction zone 2 at 350°C. The remaining syngas continues to undergo deep conversion in the main reaction zone 21 under the action of the catalyst to obtain gaseous products. The gaseous products and catalyst are discharged through the product outlet 23 on the main reaction zone 21. (6) The gaseous products and catalyst discharged from the product outlet 23 of the main reaction zone 21 enter the catalyst recovery unit 5 for separation. The gaseous products are discharged through the outlet of the catalyst recovery device and then enter the subsequent processing section. The catalyst enters the heat exchanger 42 for cooling and then returns to the transition zone 22 for recycling through the circulation pipe 44. (7) When the second reaction continues to heat up, a portion of the catalyst is taken out through the riser pipe 41, and the velocity of the riser gas (CO2) at the gas inlet 43 is controlled to be 5 m / s, thereby changing the mass of the catalyst carried out; the removed catalyst enters the heat exchanger 42 for heat exchange and cooling (the temperature of the cooling water is 130℃-150℃); the riser gas is discharged from the outlet of the heat exchanger 42, and the catalyst is returned to the transition zone 22 for recycling through the circulation pipe 44.

[0075] It should be noted that, according to the test results, in Example 4, the CO conversion rate in the first reaction zone 1 was 78%, and the CO conversion rate in the main reaction zone 21 of the second reaction zone 2 was 15%. The total CO conversion rate at the product outlet 23 reaching the main reaction zone 21 was 93%, and the selectivity of C2-C6 olefins in hydrocarbons was 90%.

[0076] Example 5 use Figure 3 The illustrated variable-diameter fluidized bed structure for syngas-to-olefins production includes a first reaction zone 1 with a diameter 1.5 times that of the main reaction zone 21, a height-to-diameter ratio of 2:1, and a second reaction zone 2 with an overall height-to-diameter ratio of 2:1. The height of the transition zone 22 is 0.5 times that of the main reaction zone 21. The porous distribution plate 13 has a porosity of 15%, a pore size of 6 mm, and a thickness of 20 mm. The specific steps include: (1) A catalyst (the active phase of the catalyst is iron carbide, the additives are sodium carbonate and cerium carbonate, and the support is carbon) is loaded into the transition zone 22 from the catalyst inlet 14. High-temperature nitrogen gas is introduced into the first reaction zone 1 from the gas inlet 11. The high-temperature nitrogen gas diffuses into the second reaction zone 2 through the through holes on the porous distribution plate 13, heating the entire fluidized bed to 420°C. (2) After heating, hydrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, and the catalyst is reduced for 3 hours at 0.1 MPa; the hydrogen gas and high-temperature nitrogen gas are discharged through the product outlet 23 of the main reaction zone 21. (3) After the catalyst reduction is completed, stop the flow of high temperature nitrogen and hydrogen, and introduce room temperature synthesis gas (CO+H2) into the first reaction zone 1 through the gas inlet 11. Gradually increase the flow rate of synthesis gas so that the heat of reaction is used to heat the synthesis gas first, and stabilize the temperature of the first reaction zone 1 at 350℃ and the pressure at 5MPa. (4) If the temperature of the first reaction zone 1 continues to rise, cooling water (saturated water at 150℃-280℃) is introduced into the heat exchange unit 3 to lower the temperature in the first reaction zone 1. (5) Due to the increase in the syngas flow rate, the gas velocity in the first reaction zone 1 increases, carrying some of the catalyst. It diffuses through the through holes on the first porous distribution plate 131 to the transition zone 22, and then enters the main reaction zone 21 of the second reaction zone 2 through the second porous distribution plate 132, controlling the overall temperature of the second reaction zone 2 at 320℃-340℃. The remaining syngas continues to undergo deep conversion in the main reaction zone 21 under the action of the catalyst to obtain gaseous products. The gaseous products and catalyst are discharged through the product outlet 23 on the main reaction zone 21. (6) The gaseous products and catalyst discharged from the product outlet 23 of the main reaction zone 21 enter the catalyst recovery unit 5 for separation. The gaseous products are discharged through the outlet of the catalyst recovery device and then enter the subsequent processing section. The catalyst enters the heat exchanger 42 for cooling and then returns to the transition zone 22 for recycling through the circulation pipe 44. (7) When the second reaction continues to heat up, a portion of the catalyst is taken out through the riser 41, and the gas velocity of the riser gas (50% CH4, 50% synthesis gas) at the gas inlet 43 is controlled to be 3 m / s, thereby changing the mass of the catalyst carried out; the removed catalyst enters the heat exchanger 42 for heat exchange and cooling (the temperature of the cooling water is 100℃); the riser gas is discharged from the outlet of the heat exchanger 42, and the catalyst is returned to the transition zone 22 for recycling through the circulation pipe 44.

[0077] It should be noted that, according to the test results, in Example 5, the CO conversion rate in the first reaction zone 1 was 65%, and the CO conversion rate in the main reaction zone 21 of the second reaction zone 2 was 31%. The total CO conversion rate at the product outlet 23 reaching the main reaction zone 21 was 96%, and the selectivity of C2-C6 olefins in hydrocarbons was 70%.

[0078] Example 6 use Figure 3 The illustrated variable-diameter fluidized bed structure for syngas-to-olefins production includes a first reaction zone 1 with a diameter 2.5 times that of the main reaction zone 21, a height-to-diameter ratio of 1.5:1, and an overall height-to-diameter ratio of the second reaction zone 2 of 1.5:1. The height of the transition zone 22 is 0.6 times that of the main reaction zone 21. The porous distribution plate 13 has a 20% open porosity, 8mm pore size, and a thickness of 15mm. The specific steps include: (1) A catalyst (the active phase of the catalyst is iron carbide, the additives are sodium carbonate and cerium carbonate, and the support is carbon) is loaded into the transition zone 22 from the catalyst inlet 14. High-temperature nitrogen gas is introduced into the first reaction zone 1 from the gas inlet 11. The high-temperature nitrogen gas diffuses into the second reaction zone 2 through the through holes on the porous distribution plate 13, heating the entire fluidized bed to 400°C. (2) After heating, hydrogen gas is introduced into the first reaction zone 1 through the gas inlet 11, and the catalyst is reduced for 1.5 hours at 0.8 MPa; the hydrogen gas and high-temperature nitrogen gas are discharged through the product outlet 23 of the main reaction zone 21. (3) After the catalyst reduction is completed, stop the flow of high temperature nitrogen and hydrogen, and introduce room temperature synthesis gas (CO+H2) into the first reaction zone 1 through the gas inlet 11. Gradually increase the flow rate of synthesis gas so that the heat of reaction is used to heat the synthesis gas first, and stabilize the temperature of the first reaction zone 1 at 250℃-280℃ and the pressure at 3MPa. (4) If the temperature of the first reaction zone 1 continues to rise, cooling water (saturated water at 150℃-180℃) is introduced into the heat exchange unit 3 to lower the temperature of the first reaction zone 1. (5) Due to the increase in the syngas flow rate, the gas velocity in the first reaction zone 1 increases, carrying some of the catalyst. It diffuses through the through holes on the first porous distribution plate 131 to the transition zone 22, and then enters the main reaction zone 21 of the second reaction zone 2 through the second porous distribution plate 132, controlling the overall temperature of the second reaction zone 2 at 320℃-350℃. The remaining syngas continues to undergo deep conversion in the main reaction zone 21 under the action of the catalyst to obtain gaseous products. The gaseous products and catalyst are discharged through the product outlet 23 on the main reaction zone 21. (6) The gaseous products and catalyst discharged from the product outlet 23 of the main reaction zone 21 enter the catalyst recovery unit 5 for separation. The gaseous products are discharged through the outlet of the catalyst recovery device and then enter the subsequent processing section. The catalyst enters the heat exchanger 42 for cooling and then returns to the transition zone 22 for recycling through the circulation pipe 44. (7) When the second reaction continues to heat up, a portion of the catalyst is taken out through the riser 41, and the velocity of the riser gas (10% synthesis gas, 90% CO2) at the gas inlet 43 is controlled to be 6 m / s, thereby changing the mass of the catalyst carried out; the removed catalyst enters the heat exchanger 42 for heat exchange and cooling (the temperature of the cooling water is 50°C); the riser gas is discharged from the outlet of the heat exchanger 42, and the catalyst is returned to the transition zone 22 for recycling through the circulation pipe 44.

[0079] It should be noted that, according to the test results in Example 6, the CO conversion rate in the first reaction zone 1 was 60%, and the CO conversion rate in the main reaction zone 21 of the second reaction zone 2 was 33%. The total CO conversion rate at the product outlet 23 reaching the main reaction zone 21 was 98%, and the selectivity of C2-C6 olefins in hydrocarbons was 81%.

[0080] In summary, the variable-diameter fluidized bed provided in this application includes a large-diameter first reaction zone, a small-diameter second reaction zone, and a transition zone at the top, bottom, and middle, separated by a porous distribution plate. The first reaction zone includes a heat exchange unit, as well as an external catalyst recovery unit and a catalyst cooling unit, allowing for independent temperature control of the first and second reaction zones and maintaining similar gas velocities and good gas-solid contact between them. Externalizing the catalyst recovery and other structures reduces the investment in high-pressure equipment, resulting in lower overall manufacturing costs and higher conversion efficiency.

[0081] Other configurations of the embodiments of this application, such as ... and ..., and operations, are known to those skilled in the art and will not be described in detail here.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A variable-diameter fluidized bed for syngas-to-olefins production, characterized in that, The fluidized bed includes: First reaction zone (1) and second reaction zone (2); The first reaction zone (1) has an air inlet (11) and an air outlet (12) at opposite ends in a first direction, with the air outlet (12) located above the air inlet (11); the air inlet (11) is used to introduce synthesis gas into the first reaction zone (1); The first reaction zone (1) is filled with a catalyst; The first reaction zone (1) and the second reaction zone (2) are connected in the first direction, and the second reaction zone (2) is located above the first reaction zone (1). The air outlet (12) is connected to the interior of the second reaction zone (2). The diameter of the first reaction zone (1) in the second direction perpendicular to the first direction is greater than the diameter of the second reaction zone (2) in the second direction.

2. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 1, characterized in that, The diameter of the first reaction zone (1) in the second direction is 1.5-3 times the diameter of the second reaction zone (2) in the second direction.

3. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 1, characterized in that, The ratio of the height of the first reaction zone (1) in the first direction to its diameter in the second direction is 1:1 to 3:1; The ratio of the height of the second reaction zone (2) in the first direction to its diameter in the second direction is 1:1 to 3:

1.

4. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 1, characterized in that, The second reaction zone (2) includes: a main reaction zone (21) and a transition zone (22); The main reaction zone (21) and the transition zone (22) are connected in the first direction, and the main reaction zone (21) is located on the side of the transition zone (22) away from the first reaction zone; The air inlet of the transition zone (22) is connected to the air outlet (12) of the first reaction zone (1), and the air outlet of the transition zone (22) is connected to the interior of the main reaction zone (21). The diameter of the transition zone (22) in the second direction gradually decreases in the direction from the first reaction zone (1) to the main reaction zone (21).

5. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 4, characterized in that, The diameter variation range of the transition zone (22) satisfies the following: the maximum diameter of the transition zone (22) in the second direction is the same as the diameter of the first reaction zone (1), and the minimum diameter of the transition zone (22) in the second direction is the same as the diameter of the main reaction zone (21).

6. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 1, characterized in that, A porous distribution plate (13) is provided between the first reaction zone (1) and the second reaction zone (2); The porous distribution plate (13) is connected to the first reaction zone (1) and the second reaction zone (2) on opposite sides in the first direction. The porous distribution plate (13) includes a plurality of through holes, which serve as the air outlet (12) of the first reaction zone (1). The porous distribution plate (13) is configured to separate the first reaction zone (1) and the second reaction zone (2), and to allow the remaining synthesis gas and part of the catalyst in the first reaction zone (1) to enter the second reaction zone (2) to continue the synthesis of olefins.

7. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 6, characterized in that, The second reaction zone (2) includes a main reaction zone (21) and a transition zone (22); the transition zone is located between the main reaction zone (21) and the first reaction zone (1); The porous distribution plate (13) includes a first porous distribution plate (131) disposed between the first reaction zone (1) and the transition zone (22), and a second porous distribution plate (132) disposed between the transition zone (22) and the main reaction zone (21).

8. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 6, characterized in that, The opening ratio of the through holes on the porous distribution plate (13) is 3%-10%; The diameter of the air outlet (12) is 20mm-100mm; The porous distribution plate (13) has a size of 10mm-30mm in the first direction.

9. The variable-diameter fluidized bed for syngas-to-olefins production according to claim 1, characterized in that, The fluidized bed further includes: a heat exchange unit (3); The heat exchange unit (3) contains a cooling medium; The heat exchange unit (3) is connected to the interior of the first reaction zone (1); The heat exchange unit (3) is configured to exchange heat with the interior of the first reaction zone (1) using the cooling medium, thereby cooling the interior of the first reaction zone (1).

10. A method for preparing olefins from syngas, characterized in that, The method employs a variable-diameter fluidized bed for olefin preparation from syngas as described in any one of claims 1-9, and the method includes: High-temperature gas is introduced into the first reaction zone (1) through the air inlet (11), and the high-temperature gas diffuses into the second reaction zone (2) through the air outlet (12) to heat the first reaction zone (1) and the second reaction zone (2). After heating, reducing gas is introduced into the first reaction zone (1) through the air inlet (11) to reduce the catalyst. Syngas is introduced into the first reaction zone (1) filled with the catalyst through the inlet (11). Under the action of the catalyst, the syngas undergoes a synthesis reaction to obtain gaseous products. The remaining synthesis gas and gaseous products in the first reaction zone (1) drive part of the catalyst into the second reaction zone (2) through the gas outlet (12), causing the remaining synthesis gas to continue to undergo olefin synthesis reaction in the second reaction zone (2) under the action of the catalyst, and obtain the gaseous products; the gaseous products include olefins.

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