A flexible ammonia synthesis column

Abstract

The application discloses a flexible ammonia synthesis tower and belongs to the technical field of ammonia synthesis equipment. The synthesis tower comprises an outer shell and an inner part. The inner part is provided with catalytic beds arranged in series. A center pipe, a middle sleeve pipe, an outer sleeve pipe and a gas collecting pipe are coaxially sleeved from inside to outside at the central axis of the catalytic beds, thereby forming four independent gas passages, i.e. a third gas passage formed by the internal cavity of the center pipe, a first annular gap gas passage formed by the annular gap between the center pipe and the middle sleeve pipe, a second annular gap gas passage formed by the annular gap between the middle sleeve pipe and the outer sleeve pipe, and a fourth annular gap gas passage formed by the annular gap between the outer sleeve pipe and the gas collecting pipe. The inner space of the upper head of the first interlayer heat exchanger of the inner part is provided with a gas converter embracing the center sleeve pipe assembly. The four gas passages are communicated with the communicating inlet pipe and the communicating outlet short section pipe, thereby realizing independent conveying and staggered flow of multiple process gases in the tower. The application has the advantages of compact structure, high space utilization rate and suitability for various ammonia synthesis processes.

Description

Technical Field

[0001] This invention relates to the field of ammonia synthesis process technology, specifically to a flexible ammonia synthesis tower, and more particularly to an internal structure of an ammonia synthesis tower with an internal gas converter and four layers of independent annular gas channels. Background Technology

[0002] The ammonia synthesis tower is the core equipment in the ammonia synthesis industry, and its performance directly determines the energy consumption, yield, and operational stability of the ammonia synthesis process. After nearly a century of development, ammonia synthesis tower technology has become quite mature, forming mainstream technical routes such as the Kellogg type, Topsoe type, Casale type, Uhde type, and Brown type.

[0003] Among existing technologies, Casale's three-bed axial-radial ammonia synthesis tower is a relatively close alternative. This approach employs three catalytic beds arranged in series, with indirect heat exchangers between the beds to cool the reactant gases, and two cooling feeders to regulate the inlet temperatures of the first and second beds respectively. However, in Casale's approach, the cooling feeder gas is directly injected into the space between the beds via external pipes. While this method is structurally simple, it has the following drawbacks given the limited internal space: First, external pipelines occupy space inside the tower, compressing the catalyst loading volume; second, the transport path of multiple gases (main process gas, zero-meter auxiliary line gas, and multiple cold auxiliary line gases) inside the tower is singular, making it impossible to achieve precise temperature gradient control; third, under high temperature and high pressure conditions, the thermal expansion treatment of multiple independent pipelines and connectors is complex, increasing the risk of thermal stress in the internal components.

[0004] To address these issues, various improvement solutions have been proposed within the industry. One approach is to use a central single-tube structure as the internal gas channel. However, this solution can only transport 1-2 gas streams simultaneously, failing to meet the need for independent transport of multiple gas streams. Its fundamental flaws lie in two aspects: firstly, the lack of a device to achieve gas direction reversal without additional space requirements (i.e., the lack of a gas converter built into the existing head space); and secondly, the absence of a fourth annular gas channel between the gas collecting pipe and the outer casing as an independent downward path for the reacted gas, necessitating the use of external pipelines for the gas circuit. Another approach involves using multiple independent pipelines arranged in parallel. However, this further encroaches on the catalyst loading space, and the design for thermal expansion compensation of the pipelines is more difficult. The inconsistent independent thermal expansion displacements of the multiple pipelines can easily lead to stress concentration at the joints.

[0005] Therefore, how to design a gas direction conversion device built into the internal space of the heat exchanger head, and construct a dedicated fourth annular gas channel between the gas collecting pipe and the outer casing as an independent downward path for the gas after reaction, so as to realize the independent transport and cross flow of multiple gases within the limited internal space, while ensuring the free expansion and thermal stress release of the internal components under high temperature conditions, is a technical problem that urgently needs to be solved in this field.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a flexible ammonia synthesis tower with an internal gas converter and four independent annular gas channels, thereby overcoming the defects in the prior art.

[0008] To achieve the above objectives, the present invention provides a flexible ammonia synthesis tower, comprising an outer shell and internal components disposed inside the outer shell, wherein the internal components are provided with a catalyst bed arranged in series, characterized in that: The inner components consist of a central tube, a middle sleeve, an outer sleeve, and a gas collecting tube, which are coaxially fitted from the inside to the outside, forming four independent gas channels. The internal space of the upper head of the first interlayer heat exchanger of the internal components is equipped with a gas converter, which does not occupy the effective volume of the tower. The gas converter is designed with a central tube, an inner sleeve, and an outer sleeve. The gas converter is connected to four gas channels through a connecting inlet pipe and a connecting outlet short section pipe, so as to realize the independent delivery and cross-flow of multiple process gases in the tower.

[0009] Preferably, in the above technical solution, the four independent gas channels are specifically as follows: The central tube has an internal cavity, which serves as the third gas passage. The annular gap between the central tube and the middle sleeve is the first annular gas passage; The annular gap between the inner sleeve and the outer sleeve serves as the second annular gas passage. The annular gap between the outer casing and the gas collecting pipe is the fourth annular gas passage.

[0010] Preferably, in the above technical solution, the flow direction and transport medium configuration of each gas channel are as follows: The third gas channel is used for the upward flow of the mixed gas of the main process gas N1 and the zero-meter auxiliary gas f0; The first annular gas passage is used for the downward flow of the second cold sub-line gas f2; The second annular gas channel is used for the upward flow of the mixed gas of the first cold sub-line gas f1 and the heat-exchanged second cold sub-line gas f2; The fourth annular gas channel serves as an independent path for the gas after the catalytic bed reaction, used to transport the gas downwards and complete the directional change.

[0011] Preferably, in the above technical solution, the gas converter is provided with a connecting inlet pipe and a plurality of connecting outlet short sections distributed in a circumferential star shape. The connecting outlet short sections pass through the middle sleeve and the outer sleeve, with one end connected to the gas converter cavity and the other end opening into the first annular gas channel.

[0012] Preferably, in the above technical solution, the second cold sub-line gas f2 enters the gas converter through the connecting inlet pipe, is introduced into the first annular gas channel downward through the connecting outlet short section pipe, enters the second interlayer heat exchanger for heat exchange, mixes with the gas after heat exchange of the first cold sub-line gas f1, and together ascends through the second annular gas channel.

[0013] Preferably, in the above technical solution, the internal components are arranged in series vertically, including a first catalytic bed, a first interlayer heat exchanger, a second catalytic bed, a second interlayer heat exchanger, and a third catalytic bed, with a bottom heat exchanger located below the third catalytic bed.

[0014] Preferably, in the above technical solution, sealing fillers are provided at the sealing parts between the outer sleeve and the middle sleeve, and between the middle sleeve and the central tube.

[0015] Preferably, in the above technical solution, the gas converter, the upper end cap, the central tube, the middle sleeve, and the outer sleeve form an integral structure that can expand axially freely, thereby realizing the self-release of thermal stress in the internal components.

[0016] Preferably, in the above technical solution, an electric furnace 9 is provided axially inside the central tube, and the mixed gas of the main line process gas N1 and the zero-meter auxiliary line gas f0 rises in the central tube and is heated by the electric furnace.

[0017] Preferably, in the above technical solution, the catalyst bed is a radial flow or axial-radial flow catalyst bed; The main process gas N1 flows down through the annular gap between the outer shell and the inner components to the bottom heat exchanger to exchange heat to 360-400°C, and then mixes with the zero-meter auxiliary gas f0 before entering the central tube and flowing upward. After heat exchange by the corresponding interlayer heat exchangers, the temperatures of the first cold sub-line gas f1 and the second cold sub-line gas f2 both rise to 360-400℃.

[0018] A gas flow control method for a flexible ammonia synthesis tower, employing any of the flexible ammonia synthesis towers described above, achieves independent and staggered flow of multiple gases through four independent annular gas channels and a gas converter, comprising the following steps: S1: The main process gas N1 descends through the annular gap at the top of the tower to the bottom heat exchanger for heat exchange to 360-400°C. After mixing with the zero-meter auxiliary gas f0, it ascends through the third gas channel. S2: The mixed gas is heated to 350-380°C and enters the first catalytic bed to react at 490-510°C. The reacting gas then flows down through the fourth annular gas channel to the first interlayer heat exchanger for cooling. S3: The gas outlet gas from the first catalytic bed is heated to 390-400℃ and then enters the second catalytic bed to react at 465-480℃; S4: The second cold sub-line gas f2 is introduced into the first annular channel for heat exchange via the gas converter. After mixing with the first cold sub-line gas f1, it goes up through the second annular channel and merges with the gas in the third gas channel before entering the third catalyst bed to react at 425-460℃. S5: The gas exiting the third catalytic bed is heated to 325-450℃ by the bottom heat exchanger before exiting the tower.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The invention achieves enhanced integration through the synergistic cooperation of an internal gas converter and a fourth annular gas channel, enabling independent transport of four gases within a minimal central axis space. The gas converter is integrated into the internal space of the interlayer heat exchanger head, utilizing the existing space of the head to complete the directional conversion of the f2 gas without the need for external piping. The fourth annular gas channel provides an independent downward path for the gas after the catalytic bed reaction between the gas collecting pipe and the outer sleeve, minimizing the radial dimension of the central sleeve assembly. These two innovations work together without encroaching on catalyst loading space, significantly improving the utilization rate of space within the tower.

[0020] The internal gas converter boasts a compact structure that occupies minimal usable space: It is completely integrated into the gas phase space within the upper head of the first interlayer heat exchanger, utilizing the existing space of the head to achieve gas direction conversion. This eliminates the need for additional effective tower volume or external piping. The star-shaped distribution of connecting outlet short sections, passing through two layers of casing, solves the problem of the passageway for f2 gas to enter the inner annular space from the outside. Through the cooperation of the connecting inlet and outlet short sections, the entry and exit conversion of f2 gas is achieved within an extremely limited internal space.

[0021] The fourth annular gas channel enables the independent downward flow of reactant gas: The fourth annular gas channel constructed between the gas collecting pipe and the outer casing provides a dedicated downward transport path for the gas after the reaction in the catalytic bed. This avoids the drawback of the traditional scheme where the reactant gas needs to complete the direction change through an external pipeline, enabling the entire four-channel system to achieve a complete transport closed loop within a very limited radial space.

[0022] Flexible and precise temperature control: The flow direction of each gas stream has been optimized from a thermodynamic perspective, and with the design of specific temperature parameters (such as the inlet / outlet temperature range of each catalyst bed), fine temperature gradient control has been achieved, which is beneficial to improving the conversion rate of ammonia synthesis.

[0023] Free thermal expansion: The gas converter is built into the upper head of the interlayer heat exchanger, forming an integrated, freely expandable structure with the upper head and the central sleeve. This effectively eliminates thermal stress concentration during high-temperature operation, improving the safety and service life of the equipment.

[0024] The synergistic effect of the built-in electric furnace: The electric furnace, built into the central tube, overlaps with the main airflow channel, and the furnace's heating path directly acts on the upward main airflow, resulting in high heating efficiency. Furthermore, since the main process gas (N1) always passes through the central tube, gas flow is guaranteed during operation, avoiding the safety hazard of requiring cold air to be supplied before power is applied to an external electric furnace, significantly improving operational safety. Simultaneously, the built-in electric furnace eliminates the need for the pressure-bearing shell and high-pressure pipelines of an external electric furnace, reducing equipment investment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of a flexible ammonia synthesis tower according to the present invention.

[0026] Figure 2 This is a partially enlarged structural diagram of the gas converter and central sleeve assembly of the present invention.

[0027] Figure 3 This is a top view of the gas converter structure of the present invention.

[0028] The reference numerals in the attached drawings are explained as follows: 1. Outer shell; 2. Internal components; 3. First catalytic bed (#1 catalytic bed); 4. First interlayer heat exchanger; 5. Second catalytic bed (#2 catalytic bed); 6. Second interlayer heat exchanger; 7. Third catalytic bed (#3 catalytic bed); 8. Bottom heat exchanger; 9. Electric furnace; 10. Gas converter; 11. Connecting outlet short section pipe; 12. Connecting inlet pipe; 13. Central pipe; 14. Middle sleeve pipe; 15. Outer sleeve pipe; 16. End cap; 17. Gas collecting pipe; 18. Sealing packing.

[0029] N1 Main line gas (process gas entering the synthesis tower); f0 Zero meter auxiliary line gas; f1 First interlayer cold gas (first cold auxiliary line gas); f2 Second interlayer cold gas (second cold auxiliary line gas).

[0030] a. A mixture of N1 and f0 gas; b. A mixture of f1 and f2 gas; c. f2 gas; d. Gas obtained after mixing gases a and b and reacting in the first catalytic bed. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0032] Example 1: Basic Structure like Figure 1 As shown, the present invention provides a flexible ammonia synthesis tower, comprising an outer shell 1 and internal components 2 disposed inside the outer shell 1. The outer shell 1 is a pressure vessel, and the internal components 2 are a detachable structure, facilitating installation, maintenance, and catalyst replacement.

[0033] The internal components 2, from top to bottom, include: a first catalytic bed 3 (#1 catalytic bed), a first interlayer heat exchanger 4, a second catalytic bed 5 (#2 catalytic bed), a second interlayer heat exchanger 6, a third catalytic bed 7 (#3 catalytic bed), and a bottom heat exchanger 8. The three catalytic beds are arranged vertically in series and all adopt radial flow or axial-radial flow design to reduce gas flow resistance.

[0034] A first interlayer heat exchanger 4 is installed between the first catalytic bed 3 and the second catalytic bed 5 to cool the gas exiting the first catalytic bed 3 to the required inlet temperature of the second catalytic bed 5. A second interlayer heat exchanger 6 is installed between the second catalytic bed 5 and the third catalytic bed 7 to cool the gas exiting the second catalytic bed 5 to the required inlet temperature of the third catalytic bed 7. A bottom heat exchanger 8 is installed below the third catalytic bed 7 to preheat the process gas entering the tower and recover heat from the gas exiting the tower.

[0035] The internal gas converter is designed to be completely integrated within the upper head 16 of the first interlayer heat exchanger 4. For example... Figure 2 , Figure 3 As shown, the gas converter 10 is an annular cavity structure surrounding the central tube 13, the middle sleeve 14, and the outer sleeve 15. The gas converter 10 has a connecting inlet pipe 12 and multiple circumferentially distributed connecting outlet short sections 11. These connecting outlet short sections 11 are arranged radially in a star shape, passing through the walls of the middle sleeve 14 and the outer sleeve 15. One end of each connecting outlet short section 11 communicates with the annular cavity of the gas converter 10, while the other end opens into the annular channel between the middle sleeve 14 and the central tube 13. This internal arrangement utilizes the existing space of the end cap to complete the gas direction conversion, eliminating the need for additional effective space within the tower or external piping. The overall structure of the gas converter 10 is tightly connected to the upper end cap 16 and the central sleeve assembly of the first interlayer heat exchanger 4, allowing for free expansion along the axial direction to accommodate thermal expansion and contraction caused by temperature changes within the tower.

[0036] Construction of the fourth annular gas channel: as follows Figure 1 , Figure 2As shown, a central sleeve assembly is installed at the central axis of the tower. This central sleeve assembly includes a central tube 13, a middle sleeve 14, an outer sleeve 15, and a gas collecting pipe 17, all coaxially arranged from the inside out. The central tube 13, middle sleeve 14, outer sleeve 15, and gas collecting pipe 17 are all concentric cylindrical structures, forming four independent annular gas channels. The annular gap between the gas collecting pipe 17 and the outer sleeve 15 constitutes another core innovation of this invention—the fourth annular gas channel, serving as an independent downward transport path for the gas after the catalytic bed reaction.

[0037] The functional division of the four independent annular channels is as follows: (1) The annular gap (fourth annular gap gas channel) between the gas collecting pipe 17 and the outer casing 15: serves as an independent downward channel for the gas after the reaction of the first catalyst bed 3 (i.e., gas d after the reaction of the #1 catalyst bed after the mixture of gas a and gas b). This allows the gas after the reaction to complete the downward turning in the central axis space without the need for external pipes. (2) The annular gap between the outer sleeve 15 and the middle sleeve 14 serves as the upward passage for the mixed gas (i.e., gas b) between the gas f1 of the first cold sub-line and the gas f2 of the second cold sub-line after heat exchange. (3) The annular gap between the middle sleeve 14 and the central tube 13 serves as the downward channel for the second cold sub-line gas f2 (i.e., gas c); (4) The internal cavity of the central tube 13 serves as the upward channel for the mixed gas (i.e., gas a) of the main process gas N1 and the zero-meter auxiliary gas f0.

[0038] Sealing packing 18 is provided at the sealing points between the outer sleeve 15 and the middle sleeve 14, and between the middle sleeve 14 and the central tube 13, to prevent gas leakage between the annular gaps.

[0039] An electric furnace 9 is axially mounted inside the cavity of the central tube 13. The electric furnace 9 has a detachable structure for easy maintenance and replacement.

[0040] Example 2: Gas Flow Direction Control Combination Figures 1 to 3 The gas flow direction of the present invention will be described in detail.

[0041] (1) Main process gas N1 path: The main process gas N1 enters the annular gap between the outer shell 1 and the inner shell 2 of the synthesis tower from the top forging, flowing downwards to the bottom of the tower. It then enters the shell side of the bottom heat exchanger 8, where it exchanges heat with the high-temperature reaction gas exiting the third catalytic bed 7, adjusting the temperature of the process gas exiting the tower to 330–420°C. Simultaneously, the tower wall temperature is controlled to increase the operational stability and safety of the synthesis tower. After heat exchange, the gas temperature rises to 360–400°C and mixes with the zero-meter auxiliary gas f0.

[0042] (2) Gas path f0 in the zero-meter sub-line: The zero-meter auxiliary gas f0 is introduced from the top of the tower to adjust the inlet temperature of the first catalyst bed 3 in the synthesis tower to 350-380℃, so as to adapt to different operating conditions of the synthesis tower. f0 mixes with N1 gas preheated by the bottom heat exchanger 8 at the bottom of the tower. The mixed gas (i.e., gas a) enters the internal cavity of the central tube 13 and flows upward along the central tube 13. During the upward flow, it flows through the electric furnace 9 set in the central tube 13. During operation, the electric furnace 9 heats the gas to the catalyst activation temperature.

[0043] (3) Gas path f1 in the first cold sub-line: The first cold side gas f1 is introduced from the top of the tower and enters the shell side of the first interlayer heat exchanger 4 from the upper part of the first interlayer heat exchanger 4. It exchanges heat with the hot gas at the outlet of the first catalytic bed 3. After the heat exchange, the gas temperature rises to 360-400℃, which is used to adjust the inlet temperature of the second catalytic bed 5.

[0044] (4) Gas path f2 in the second cold sub-line (direction conversion achieved using an internal gas converter): The second cold side gas f2 is introduced from the top of the tower and enters the tube side of the second interlayer heat exchanger 6 from the upper part of the second interlayer heat exchanger 6. It exchanges heat with the hot gas at the outlet of the second catalytic bed 5. After the heat exchange, the gas temperature rises to 360-400℃, which is used to regulate the inlet temperature of the second catalytic bed 5.

[0045] Specifically, gas f2 flows downward through the connecting inlet pipe 12 into the gas converter 10, which is built into the upper head 16 of the first interlayer heat exchanger 4. After being split by the annular cavity of the gas converter 10, it passes through multiple star-shaped connecting outlet short sections 11, through the walls of the outer sleeve 15 and the middle sleeve 14, and enters the annular gap (i.e., the third channel, c gas channel) between the middle sleeve 14 and the central pipe 13. It then flows downward along this annular gap to the second interlayer heat exchanger 6 for heat exchange. This process completely utilizes the original space inside the upper head to complete the gas direction conversion without occupying any additional effective volume inside the tower.

[0046] (5) Catalytic reaction and interlayer flow (using the fourth annular gas channel to achieve independent downward flow of reactant gases): The mixed gas (N1 + f0 mixed gas a) is conditioned to 350–380°C via the zero-meter auxiliary gas f0 before entering the first catalytic bed 3 (#1 catalytic bed) for ammonia synthesis. After the reaction, the gas temperature rises to 490–510°C. This reaction gas (i.e., gas d: the gas after the mixture of gas a and gas b reacts in the #1 catalytic bed) descends independently through the fourth annular gas channel between the gas collecting pipe 17 and the outer casing 15, entering the first interlayer heat exchanger 4 for cooling. This fourth annular gas channel provides a dedicated downward transport path for the reaction gas, eliminating the need for external pipelines.

[0047] The gas exiting the first catalytic bed 3 is cooled by the first interlayer heat exchanger 4, and then adjusted to 390-400°C by the first cold auxiliary gas f1 before entering the second catalytic bed 5 (#2 catalytic bed) for ammonia synthesis reaction. After the reaction, the gas temperature rises to 465-480°C.

[0048] The gas exiting the second catalytic bed 5 is cooled by the second interlayer heat exchanger 6 and then adjusted to 390-400°C by the second cold auxiliary gas f2 before entering the third catalytic bed 7 (#3 catalytic bed) for ammonia synthesis. After the reaction, the gas temperature rises to 425-460°C.

[0049] At the second interlayer heat exchanger 6, the gas after heat exchange by f2 and the gas after heat exchange by f1 mix to become gas b, and together enter the annular gap (i.e., the second channel) between the outer sleeve 15 and the middle sleeve 14, flow upward to the top of the inner part, and merge with the gas a rising from the central tube 13.

[0050] (6) Exiting the tower: After the reaction in the third catalytic bed 7, the gas enters the shell side of the bottom heat exchanger 8 in the radial direction and exchanges heat with the cold gas (i.e. the N1 main gas entering the tower) from the bottom heat exchanger 8. After the heat exchange, the temperature drops to 325-450℃ and then exits the tower and is sent to the subsequent cooling and separation system.

[0051] In a preferred embodiment of the present invention, the electric furnace 9 is disposed inside the central tube 13, the main advantage of which is: (1) Reduced investment: The pressure-bearing shell and high-pressure pipeline that need to be equipped separately for external electric furnaces are eliminated, reducing equipment manufacturing costs and installation space requirements.

[0052] (2) Avoid the disadvantageous operation that requires the external electric furnace to be powered on before it can be put into operation: Since the electric furnace 9 is built into the central tube 13, and the central tube 13 is the necessary channel for the main process gas N1 - as long as the synthesis tower is put into operation, N1 will definitely have gas passing through it. Therefore, the heating path of the electric furnace 9 always coincides with the main gas flow channel, and it can safely provide heat to the ammonia synthesis tower without additional operation, which significantly improves the convenience and safety of operation.

[0053] Technical effect analysis The flexible ammonia synthesis tower of the present invention, under the same catalyst loading and operating conditions, has the following technical advantages compared with the traditional Casale-type three-bed synthesis tower: (1) The catalyst loading increases by about 5% to 8%. Since the central sleeve assembly adopts a multi-layer coaxial sleeve structure and the gas converter is built into the internal space of the interlayer heat exchanger head, the fourth annular gas channel utilizes the existing annular structure between the gas collecting pipe and the outer sleeve. Compared with the scheme of multiple independent pipes, it significantly saves central space and increases the effective volume of the catalyst basket.

[0054] (2) More uniform temperature distribution. The four independent annular channels enable precise control of gases at different temperatures. Through the independent flow regulation of the four gases N1, f0, f1, and f2, the inlet temperature of each catalyst bed can be precisely controlled within the target temperature range of ±3℃ (f0→350~380℃, f1→390~400℃, f2→390~400℃), which is beneficial to improving the net ammonia value.

[0055] (3) The structure is compact and maintainable. The internal gas converter is arranged in the gas phase space inside the upper head of the first interlayer heat exchanger, and the fourth annular gas channel is constructed using the existing space between the gas collecting pipe and the outer sleeve. Both innovations do not occupy additional effective space inside the tower, so that the f2 gas can be directly injected into the second interlayer heat exchanger without external pipes, and the reaction gas can complete the downward turning without external pipes, simplifying the pipeline layout inside the tower.

[0056] (4) Applicable to new construction or renovation projects of ammonia synthesis plants of various scales. The internal components of the present invention adopt a modular design and are used in conjunction with the outer shell 1 of the existing ammonia synthesis tower. Upgrades and renovations can be completed by simply replacing the internal components 2, with a short renovation cycle and low investment.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flexible ammonia synthesis tower, comprising an outer shell (1) and an inner component (2) disposed inside the outer shell (1), wherein the inner component (2) is provided with a catalyst bed arranged in series, characterized in that: The inner component (2) consists of a central tube (13), a middle sleeve (14), an outer sleeve (15), and a gas collecting tube (17) coaxially arranged from the inside to the outside, forming four independent gas channels. The upper end cap (16) of the first interlayer heat exchanger (4) of the inner component (2) is equipped with a gas converter (10). The gas converter (10) is arranged around the central tube (13), the middle sleeve (14), and the outer sleeve (15). The gas converter (10) is connected to four gas channels through the connecting inlet pipe (12) and the connecting outlet short section pipe (11) to realize the independent transportation and cross flow of multiple process gases in the tower. The four independent gas channels are as follows: the internal cavity of the central tube (13) is the third gas channel; the annular gap between the central tube (13) and the middle sleeve (14) is the first annular gas channel; the annular gap between the middle sleeve (14) and the outer sleeve (15) is the second annular gas channel; and the annular gap between the outer sleeve (15) and the gas collecting tube (17) is the fourth annular gas channel.

2. The flexible ammonia synthesis tower according to claim 1, characterized in that, The flow direction and transport medium configuration of each gas channel are as follows: The third gas channel is used for the upward flow of the mixed gas of the main process gas (N1) and the zero-meter auxiliary gas (f0); The first annular gas channel is used for the downward flow of the second cold sub-line gas (f2); The second annular gas channel is used for the upward flow of the mixture of the first cold sub-line gas (f1) and the heat-exchanged second cold sub-line gas (f2); The fourth annular gas channel serves as an independent path for the gas after the catalytic bed reaction, used to transport the gas downwards and complete the directional change.

3. The flexible ammonia synthesis tower according to claim 1, characterized in that, The gas converter (10) is provided with a connecting inlet pipe (12) and a plurality of connecting outlet short sections (11) distributed in a circumferential star shape. The connecting outlet short sections (11) pass through the middle sleeve (14) and the outer sleeve (15), with one end connected to the cavity of the gas converter (10) and the other end opening into the first annular gas channel.

4. The flexible ammonia synthesis tower according to claim 3, characterized in that, The second cold sub-line gas (f2) enters the gas converter (10) through the connecting inlet pipe (12), and is introduced into the first annular gas channel downward through the connecting outlet short section pipe (11). After entering the second interlayer heat exchanger (6) for heat exchange, it mixes with the gas after heat exchange of the first cold sub-line gas (f1) and goes up together through the second annular gas channel.

5. The flexible ammonia synthesis tower according to claim 1, characterized in that, The internal components 2 are arranged in series vertically, including a first catalytic bed (3), a first interlayer heat exchanger (4), a second catalytic bed (5), a second interlayer heat exchanger (6), and a third catalytic bed (7). A bottom heat exchanger (8) is provided below the third catalytic bed (7).

6. The flexible ammonia synthesis tower according to claim 1, characterized in that, The sealing parts between the outer sleeve (15) and the middle sleeve (14), and between the middle sleeve (14) and the central tube (13) are provided with sealing filler (18).

7. The flexible ammonia synthesis tower according to claim 1, characterized in that, The gas converter (10), together with the upper end cap (16), the central tube (13), the middle sleeve (14), and the outer sleeve (15), forms an integral structure that can expand axially freely, thereby realizing the self-release of internal thermal stress.

8. The flexible ammonia synthesis tower according to claim 1, characterized in that, An electric furnace 9 is installed axially inside the central tube (13). The mixed gas of the main process gas (N1) and the zero-meter auxiliary gas (f0) rises in the central tube (13) and is heated by the electric furnace 9.

9. The flexible ammonia synthesis tower according to claim 1, characterized in that, The catalyst bed is a radial flow or axial-radial flow catalyst bed; The main process gas (N1) flows down through the annular gap between the outer shell 1 and the inner part 2 to the bottom heat exchanger (8) to exchange heat to 360-400°C, and then mixes with the zero-meter auxiliary gas (f0) before entering the central tube (13) and rising. The temperatures of the first cold sub-line gas (f1) and the second cold sub-line gas (f2) rise to 360-400℃ after heat exchange through the corresponding interlayer heat exchangers.

10. A method for controlling the gas flow direction in a flexible ammonia synthesis tower, characterized in that, The flexible ammonia synthesis tower according to any one of claims 1 to 10 achieves independent and staggered flow of multiple gases through four independent annular gas channels and a gas converter (10), including the following steps: S1: The main process gas (N1) flows down through the annular gap at the top of the tower to the bottom heat exchanger (8) to exchange heat to 360-400°C. After mixing with the zero-meter auxiliary gas (f0), it flows up through the third gas channel. S2: The mixed gas is heated to 350-380℃ and enters the first catalytic bed (3) to react to 490-510℃. The reacting gas goes down through the fourth annular gas channel to the first interlayer heat exchanger (4) for cooling. S3: The outlet gas of the first catalyst bed (3) is heated to 390-400℃ and enters the second catalyst bed (5) to react at 465-480℃; S4: The second cold sub-line gas (f2) is introduced into the first annular channel for heat exchange via the gas converter (10), mixes with the first cold sub-line gas (f1), and then goes up through the second annular channel. After merging with the gas in the third gas channel, it enters the third catalyst bed (7) and reacts to 425-460°C. S5: The gas from the outlet of the third catalytic bed (7) is heated to 325-450℃ by the bottom heat exchanger (8) and then exits the tower.

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