Double-tower dynamic series-parallel flexible ammonia synthesis system and control method
By using a dual-tower dynamic series-parallel flexible ammonia synthesis system, the problem of narrow load adjustment range of traditional single-tower ammonia synthesis units is solved by combining the series and parallel connections of the two synthesis towers and valve control. This achieves a wider load range and faster response, adapting to fluctuations in renewable energy output.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AN HUI ZHONG KE HE CHENG LV SE NENG YUAN YOU XIAN GONG SI
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional single-tower ammonia synthesis units have a narrow load adjustment range, making it difficult to match the fluctuations in renewable energy output, which limits the industrialization of green ammonia.
A flexible ammonia synthesis system with dual-tower dynamic series-parallel connection is adopted. By combining the series and parallel connection of the two synthesis towers, and using a valve system to control the pipeline on and off, the load range can be widened and the response can be rapid.
It broadens the load range of the ammonia synthesis system, improves the system's flexibility and response speed, reduces energy consumption, and adapts to the output fluctuations of renewable energy.
Smart Images
Figure CN122010142A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ammonia synthesis technology, specifically to a dual-tower dynamic series-parallel flexible ammonia synthesis system and its control method. Background Technology
[0002] Under the global "dual carbon" goal, green ammonia has become a core value as a zero-carbon fuel and green chemical raw material. It achieves near-zero emissions throughout its entire life cycle by producing green hydrogen through renewable energy electrolysis of water and then synthesizing it with nitrogen. It can also help with the consumption and storage of wind and solar energy. However, the intermittency of wind and solar power generation leads to rapid load fluctuations in the upstream hydrogen production section, which contradicts the stable operation mode of the traditional ammonia synthesis section and restricts the industrialization of green ammonia.
[0003] Traditional single-tower ammonia synthesis units are limited by catalyst activity windows, bed thermal balance control capabilities, and reaction kinetics, resulting in a narrow load adjustment range and slow response. They typically operate efficiently only within a narrow steady-state range. To accommodate fluctuations in wind and solar power resources, the synthesis tower load needs a wide adjustment range. Currently, the industry generally demands green ammonia synthesis equipment with a wide load operating capability of 30%-110% or more to match the power output fluctuations of renewable energy sources. Summary of the Invention
[0004] The present invention aims to solve the problem of narrow load capacity in existing single-tower ammonia synthesis units.
[0005] To address the aforementioned problems, in a first aspect, the present invention provides a dual-tower dynamic series-parallel flexible ammonia synthesis system, comprising a first synthesis tower, a second synthesis tower, and a raw material supply source; Both the first and second synthesis towers have input and output systems. The pipeline system includes a first pipeline group located between the raw material supply source and the input system of the first synthesis tower, a second pipeline group located between the raw material supply source and the input system of the second synthesis tower, a third pipeline group located between the input system of the first synthesis tower and the output system of the second synthesis tower, and a fourth pipeline group located between the output system of the first synthesis tower and the input system of the second synthesis tower. The fourth pipeline group is not connected to the third pipeline group in the second synthesis tower. A valve system is used to control the opening and closing of corresponding pipelines in a pipeline system. A valve system has at least a first operating condition and a second operating condition. Under the first operating condition, the first pipeline group is connected, the second pipeline group is connected, the third pipeline group is disconnected, and the fourth pipeline group is disconnected. In the second operating condition, the second pipeline group is connected, the third pipeline group is connected, the fourth pipeline group is connected, and the first pipeline group is disconnected.
[0006] The present invention provides a dual-tower dynamic series-parallel flexible ammonia synthesis system and control method, which, compared with the prior art, has the following beneficial effects, but are not limited to: Since the minimum load required for a single synthesis tower to achieve self-heating balance is still relatively high, the number of synthesis towers used for ammonia synthesis is increased to two. Connecting them in series further reduces the minimum load of the ammonia synthesis system, while connecting them in parallel increases the maximum load. This broadens the load range of the entire system, allowing it to match the power output fluctuations of renewable energy sources. Furthermore, the system uses a valve system to control the on / off state of corresponding pipelines in the pipeline system, enabling two operating conditions. In the first condition, both the first and second pipeline groups remain connected, allowing the corresponding first and second synthesis towers to operate independently, achieving high-load operation of the entire system or meeting the system's operating conditions for the first and second synthesis towers, allowing their load to increase independently and steadily. In the second condition, the second pipeline group... The third and fourth pipeline groups are connected, allowing gas supplied from the raw material source to enter the second synthesis tower, transfer from the second synthesis tower to the first synthesis tower, then from the first synthesis tower to the second synthesis tower, and finally exit from the second synthesis tower. This operating condition allows the second synthesis tower to remain in hot standby mode even when the first synthesis tower is under high load. At extremely low load, the temperature can be maintained as much as possible by passing the high-temperature synthesis gas from the first synthesis tower into the second synthesis tower. The advantage is that when the total load increases again, because the catalyst in the second synthesis tower is kept at a high temperature by the reactant gas in the first synthesis tower, when the second synthesis tower needs to be put back into use, it can reach the temperature required for the catalyst reaction more quickly compared to the non-hot standby state, saving time and energy.
[0007] As a further aspect of the present invention: the maximum load of the first synthesis tower is lower than the maximum load of the second synthesis tower.
[0008] As a further aspect of the present invention, the ratio between the maximum load of the first synthesis tower and the maximum load of the second synthesis tower is between 0.25 and 0.5.
[0009] As a further aspect of the present invention: the input system of the second synthesis tower includes a tower wall gas input terminal; the output system of the second synthesis tower includes a tower wall gas output terminal, the tower wall gas input terminal being connected to the tower wall gas output terminal within the second synthesis tower; the input system of the second synthesis tower also includes a supplementary input terminal, a supplementary pipeline being provided between the tower wall gas output terminal and the corresponding supplementary input terminal, and a supplementary valve being provided in the supplementary pipeline; in the first operating condition, the supplementary valve is opened, connecting the supplementary pipeline; in the second operating condition, the supplementary valve is closed, disconnecting the supplementary pipeline; the input system also includes a heating gas input terminal and a branch gas input terminal, the heating gas input terminal being connected to a heating device via a pipeline; the output system also includes a reaction gas output terminal; within the first synthesis tower, the heating gas input terminal and the branch gas input terminal are connected to the corresponding reaction gas output terminal; within the second synthesis tower, the heating gas input terminal, the supplementary input terminal, and the branch gas input terminal are connected to the corresponding reaction gas output terminal.
[0010] As a further aspect of the present invention: the first pipeline group includes a first main pipeline and a first pipeline connected to the raw material supply source. One end of the first main pipeline is connected to one end of all the first pipelines. The heating device on the first synthesis tower and the branch gas input end are both connected to one of the first pipelines. The valve system includes a first main valve installed on the first main pipeline, a first valve installed on the first pipeline connected to the heating device, and a second valve installed on the other first pipelines. The second pipeline group includes a second main pipeline and a second pipeline connected to the raw material supply source. One end of the second main pipeline is connected to one end of all the second pipelines. The heating device on the second synthesis tower, the branch gas input end and the tower wall gas input end are all connected to one of the second pipelines. The valve system includes a third valve installed on each second pipeline. The third pipeline group includes a third main pipeline, one end of which is connected to the tower wall gas output end of the second synthesis tower, and the other end of which is connected to the first main pipeline. The connection point is located between the first main valve and the first pipeline. The valve system includes a second main valve installed on the third main pipeline. The fourth pipeline group includes a fourth main pipeline, one end of which is connected to the reaction gas output end of the first synthesis tower, and the other end of which is connected to the heating device on the second synthesis tower. The connection point is located on the pipeline between the input end of the heating device and the corresponding third valve. The valve system includes a third main valve installed on the fourth main pipeline.
[0011] As a further aspect of the present invention: the number of branch gas input terminals on the first synthesis tower is n, and the number of branch gas input terminals on the second synthesis tower is m, where n is an integer not less than 1 and m is an integer not less than 0.
[0012] As a further aspect of the present invention: the pipeline system includes an exhaust pipeline, the exhaust pipeline on the second synthesis tower is connected to the corresponding reaction gas output end, the exhaust pipeline on the first synthesis tower is connected to the corresponding reaction gas output end or to the fourth main pipeline, and the connection point is located on the pipeline between the third main valve and the corresponding reaction gas output end; the valve system includes an exhaust valve installed in the exhaust pipeline on the first synthesis tower; the raw material supply source includes a heat exchanger and a main input line; the pipeline system includes a main output line; the heat exchanger has a first channel and a second channel; one end of the first channel is connected to the main input line, and the other end of the first channel is connected to both the first main pipeline and the second main pipeline; one end of the second channel is connected to the main output line, and the other end of the second channel is connected to both exhaust pipelines.
[0013] Secondly, the present invention provides a control method based on the above-described dual-tower dynamic series-parallel flexible ammonia synthesis system, comprising the following steps: S10a, controlling the valve system to connect the second pipeline group, the third pipeline group, and the fourth pipeline group, and disconnecting the first pipeline group.
[0014] This invention also provides a control method for a dual-tower dynamic series-parallel flexible ammonia synthesis system, which, compared with the prior art, has, but is not limited to, the following beneficial effects: Connecting the second, third, and fourth pipeline groups while disconnecting the first pipeline group allows the system to operate under low load conditions. This enables the high-temperature reaction gas from the first synthesis tower to insulate the catalytic bed in the second synthesis tower, while simultaneously controlling the temperature of the tower body from the raw material supply. This maintains the catalytic temperature of the second synthesis tower as much as possible, allowing the dual-tower system to achieve a wider load range while consuming less energy, adjusting faster, and responding more responsively when transitioning from low to high load conditions.
[0015] As a further aspect of the present invention: step S10a includes controlling the first main valve in the control valve system to close, controlling the third valve on the second pipeline connected to the tower wall gas input end to open, controlling the remaining third valves to close, controlling the supplementary valve to close, controlling the second main valve to open, controlling the first valve to close, controlling the second valve to open, controlling the discharge valve to close, and controlling the third main valve to open.
[0016] The present invention also provides a control method based on the above-described dual-tower dynamic series-parallel flexible ammonia synthesis system, comprising the following steps: S10b, controlling the valve system to connect the first pipeline group, connect the second pipeline group, disconnect the third pipeline group, and disconnect the fourth pipeline group.
[0017] This invention also provides a control method for a dual-tower dynamic series-parallel flexible ammonia synthesis system, which, compared with the prior art, has, but is not limited to, the following beneficial effects: Connecting the first pipeline group, connecting the second pipeline group, disconnecting the third pipeline group, and disconnecting the fourth pipeline group allows the first and second synthesis towers to be supplied with gas and loaded independently, thus achieving two possible operating conditions: one is the start-up condition, in which the first and second synthesis towers gradually increase their load; the other is the high-load condition, in which both the first and second synthesis towers are used for the catalytic synthesis of ammonia. Attached Figure Description
[0018] The invention will now be further described with reference to the accompanying drawings.
[0019] Figure 1 This is a schematic diagram of the overall system flow of the present invention.
[0020] In the diagram: 1. First synthesis tower; 2. Second synthesis tower; 3. Raw material supply; 31. Heat exchanger; 32. Main input line; 33. Main output line; 4. Piping system; 41. Supplementary pipeline; 42. Discharge pipeline; 43. First main pipeline; 431. First pipeline; 44. Second main pipeline; 441. Second pipeline; 45. Third main pipeline; 46. Fourth main pipeline; 5. Valve system; 51. Supplementary valve; 52. First main valve; 53. First valve; 54. Second valve; 55. Third valve; 56. Second main valve; 57. Third main valve; 58. Discharge valve; 61. Heating gas input; 62. Branch gas input; 63. Tower wall gas input; 64. Supplementary input; 71. Tower wall gas output; 72. Reaction gas output; 8. Heating device. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings showing multiple embodiments according to this application. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.
[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," etc., in the description, claims, and accompanying drawings of this application are open-ended terms. Therefore, "comprising," "including," or "having" refers to, for example, a method or apparatus having one or more steps or elements, but is not limited to having only these one or more elements. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.
[0023] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.
[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0025] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.
[0026] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.
[0027] like Figure 1 As shown, a dual-tower dynamic series-parallel flexible ammonia synthesis system includes a first synthesis tower 1, a second synthesis tower 2, and a raw material supply 3; both the first synthesis tower 1 and the second synthesis tower 2 have input and output systems; a pipeline system 4 includes a first pipeline group located between the raw material supply 3 and the input system of the first synthesis tower 1, a second pipeline group located between the raw material supply 3 and the input system of the second synthesis tower 2, a third pipeline group located between the input system of the first synthesis tower 1 and the output system of the second synthesis tower 2, and a fourth pipeline group located between the output system of the first synthesis tower 1 and the input system of the second synthesis tower 2, wherein the fourth pipeline group is not connected to the third pipeline group within the second synthesis tower 2; and a valve system 5 is used to control the on / off state of corresponding pipelines in the pipeline system 4, the valve system 5 having at least a first operating condition and a second operating condition; in the first operating condition, the first pipeline group is connected, the second pipeline group is connected, the third pipeline group is disconnected, and the fourth pipeline group is disconnected; in the second operating condition, the second pipeline group is connected, the third pipeline group is connected, the fourth pipeline group is connected, and the first pipeline group is disconnected.
[0028] It is understandable that when the valve system 5 is in the first operating condition, the first synthesis tower 1 and the second synthesis tower 2 are equivalent to being connected in series; when the valve system 5 is in the second operating condition, the first synthesis tower 1 and the second synthesis tower 2 are equivalent to being connected in parallel.
[0029] In this embodiment, since the minimum load required for a single synthesis tower to achieve self-heating balance is still relatively high, the number of synthesis towers used for ammonia synthesis is increased to two. When connected in series, the minimum load of the ammonia synthesis system can be further reduced, and when connected in parallel, the maximum load of the ammonia synthesis system can be increased. This helps to broaden the load range of the entire system and enable it to match the output fluctuation characteristics of renewable energy.
[0030] As an exemplary explanation, the total load of the synthesis tower system is 1, and the minimum load of a single synthesis tower cannot be less than a, where 0% < a < 100%. When the maximum loads of two synthesis towers are the same, the maximum load of a single synthesis tower is 0.5 of the total load, and the minimum load of a single synthesis tower is 0.5a of the total load. If there is only one synthesis tower and the total load of this synthesis tower is 1, and the minimum load of a single synthesis tower cannot be less than a, 0% < a < 100%, then the minimum load of this synthesis tower is 1×a = a of the total load. Thus, it can be seen that when the total loads of two systems are the same, the minimum load of the system with two synthesis towers can be significantly lower than the minimum load value of the system with only one synthesis tower.
[0031] And in this system, the on / off of the corresponding pipelines in the pipeline system 4 is controlled by the valve system 5, so that the system has two working conditions. In the first working condition, both the first pipeline group and the second pipeline group remain in a connected state, enabling the corresponding first synthesis tower 1 and second synthesis tower 2 to work independently, achieving high-load operation of the overall system or meeting the start-up conditions of the first synthesis tower 1 and the second synthesis tower 2, and enabling their loads to increase independently and steadily. In the second working condition, the second pipeline group, the third pipeline group, and the fourth pipeline group are in a connected state, allowing the gas supplied from the raw material source 3 to enter the second synthesis tower 2, transfer from the second synthesis tower 2 to the first synthesis tower 1, then transfer from the first synthesis tower 1 to the second synthesis tower 2, and finally be removed from the second synthesis tower 2. This working condition can meet the requirement that when the first synthesis tower is at a relatively high load, the second synthesis tower 2 can still be in hot standby through intake air, and at extremely low loads, the high-temperature reaction gas in the first synthesis tower 1 can be introduced into the second synthesis tower 2 to maintain the temperature as much as possible. The advantage is that when the total load rises again, because the catalyst in the second synthesis tower 2 has been maintained at a relatively high temperature by the reaction gas of the first synthesis tower 1 during hot standby, when the second synthesis tower 2 needs to be put into use again, it can reach the temperature required for the catalyst reaction more quickly compared to the non-hot standby state, saving time and energy.
[0032] Optionally, the maximum load of the first synthesis tower 1 is lower than the maximum load of the second synthesis tower 2.
[0033] In this embodiment, since the synthesis tower has a minimum load value and is in a certain proportion to the maximum load of the synthesis tower, by limiting the maximum load of the first synthesis tower 1 to be lower than the maximum load of the second synthesis tower 2, the overall minimum load in this system can reach the minimum load of the first synthesis tower 1, so that the overall minimum load can be lower without changing the overall maximum load of the system, which is beneficial to further realizing wide-range adjustment of the load and enabling the system to be more flexible in matching with the power fluctuation of renewable energy.
[0034] Optionally, the ratio between the maximum load of the first synthesis tower 1 and the maximum load of the second synthesis tower 2 is between 0.25 - 0.5.
[0035] In this embodiment, the ratio of the maximum load of the first synthesis tower 1 to the maximum load of the second synthesis tower 2 is limited to between 0.25 and 0.5, thus defining the maximum and minimum values in the feasible dual-tower ammonia synthesis scheme and ensuring the feasibility of the present invention.
[0036] Optionally, the input system of the second synthesis tower 2 includes a tower wall gas input terminal 63; the output system of the second synthesis tower 2 includes a tower wall gas output terminal 71, the tower wall gas input terminal 63 is connected to the tower wall gas output terminal 71 inside the second synthesis tower 2, the input system of the second synthesis tower 2 also includes a supplementary input terminal 64, a supplementary pipeline 41 is provided between the tower wall gas output terminal 71 and the corresponding supplementary input terminal 64, and a supplementary valve 51 is provided in the supplementary pipeline 41. Under the first operating condition, the valve system 5 opens the supplementary valve 51, connecting the supplementary pipeline 41; In the second operating condition, the gate system 5 closes the supplement valve 51, disconnecting the supplement pipeline 41. The input system also includes a heating gas input terminal 61 and a branch gas input terminal 62. The heating gas input terminal 61 is connected to a heating device 8 via a pipeline. The output system also includes a reaction gas output terminal 72. In the first synthesis tower 1, the heating gas input terminal 61 and the branch gas input terminal 62 are connected to the corresponding reaction gas output terminal 72. In the second synthesis tower 2, the heating gas input terminal 61, the supplement input terminal 64, and the branch gas input terminal 62 are connected to the corresponding reaction gas output terminal 72.
[0037] For example, the heating device 8 can be implemented as either a heating furnace or an electric heater.
[0038] In this embodiment, the tower wall gas inlet 63 is connected to the tower wall gas outlet 71 for temperature control of the tower body. The supplementary pipeline 41 is used to reintroduce the tower wall gas discharged from the tower wall gas outlet 71 into the tower bed for the catalytic reaction of ammonia synthesis. Under the first operating condition, the supplementary valve 51 is opened to allow the tower wall gas to enter the tower for reaction. Under the second operating condition, the supplementary valve 51 is closed so that the tower wall gas only enters the input system of the first synthesis tower 1 from the output system of the second synthesis tower 2, so that the tower wall gas is mainly used for the catalytic reaction of ammonia synthesis in the first synthesis tower 1. The heating gas inlet 61 is connected to the heating device 8 via a pipeline to heat the gas. The heating gas inlet 61 and the branch gas inlet 62 are connected to the reaction gas outlet 72 in the first synthesis tower 1 to discharge the gas after reaction. The heating gas inlet 61, the branch gas inlet 62 and the corresponding supplementary inlet 64 are connected to the reaction gas outlet 72 in the second synthesis tower 2 to discharge the gas after reaction.
[0039] Optionally, the first pipeline group includes a first main pipeline 43 connected to the raw material supply source 3 and a first pipeline 431. One end of the first main pipeline 43 is connected to one end of all the first pipelines 431. The heating device 8 and the branch gas input end 62 on the first synthesis tower 1 are both connected to one of the first pipelines 431. The valve system 5 includes a first main valve 52 installed on the first main pipeline 43, a first valve 53 installed on the first pipeline 431 connected to the heating device 8, and a second valve 54 installed on the other first pipelines 431. The second pipeline group includes a second main pipeline 44 and a second pipeline 441 connected to the raw material supply source 3. One end of the second main pipeline 44 is connected to one end of all the second pipelines 441. The heating device 8, the branch gas input end 62 and the tower wall gas input end 63 on the second synthesis tower 2 are all connected to one of the second pipelines 441. The valve system 5 includes a third valve 55 installed on each second pipeline 441. The third pipeline group includes a third main pipeline 45, one end of which is connected to the tower wall gas output end 71 of the second synthesis tower 2, and the other end of which is connected to the first main pipeline 43. The connection point is located between the first main valve 52 and the first pipeline 431. The valve system 5 includes a second main valve 56 installed on the third main pipeline 45. The fourth pipeline group includes a fourth main pipeline 46. One end of the fourth main pipeline 46 is connected to the reaction gas output end 72 of the first synthesis tower 1, and the other end of the fourth main pipeline 46 is connected to the heating device 8 on the second synthesis tower 2. The connection point is located on the pipeline between the input end of the heating device 8 and the corresponding third valve 55. The valve system 5 includes a third main valve 57 installed on the fourth main pipeline 46.
[0040] In this embodiment, each primary pipeline 431 is used to connect each input end on the first synthesis tower 1, so that the pipelines are connected in parallel and do not affect each other. The primary valve 52 is used to control the gas inlet pipeline of the entire first synthesis tower 1, and is used to close the direct gas supply channel from the raw material supply source 3 to the first synthesis tower 1 in the second working condition of the valve system 5, so that the reaction gas can only enter the second synthesis tower 2 first. The secondary valve 54 is used to control the independent opening and closing of the corresponding primary pipeline 431. The second pipeline 441 is used to connect the various input ends on the second synthesis tower 2, so that its pipeline branches can be connected in parallel and do not affect each other. The third valve 55 is used to control the independent on / off of the corresponding second pipeline 441. The third main pipeline 45 is used to introduce the tower wall gas used for temperature control of the second synthesis tower 2 (to prevent the tower wall from overheating) into the first synthesis tower 1 for reaction. The second main valve 56 is used to control the opening and closing of this pipeline. When the valve system 5 is in the first operating condition, the second main valve 56 is closed, causing the third main pipeline 45 to disconnect. When the valve system 5 is in the second operating condition, the second main valve 56 is opened, causing the third main pipeline 45 to connect. The fourth main pipeline 46 is used to introduce the high-temperature reaction gas from the first synthesis tower 1 into the second synthesis tower 2, and further heat it through the heating device 8 to keep the catalyst bed in the second synthesis tower 2 warm, preventing the catalyst bed from cooling down. This allows the catalyst bed in the second synthesis tower 2 to reach the reaction temperature more quickly when the overall system load increases, saving time and energy. Moreover, without heat preservation, the catalyst bed in the second synthesis tower 2 would require more heat and energy to heat from low temperature shutdown to the catalyst's initial activity temperature.
[0041] Understandably, when the temperature of the high-temperature reaction gas is sufficient, the heating device 8 may not need to be turned on, allowing only the high-temperature reaction gas to pass through, in order to save energy and avoid excessively high temperatures.
[0042] Optionally, the number of branch gas input terminals 62 on the first synthesis tower 1 is n, and the number of branch gas input terminals 62 on the second synthesis tower 2 is m, where n is an integer not less than 1 and m is an integer not less than 0.
[0043] In this embodiment, both the first synthesis tower 1 and the second synthesis tower 2 can be configured as single-stage, two-stage, three-stage, or multi-stage catalyst bed axial / radial / axial-radial ammonia synthesis towers. When the first synthesis tower 1 is a single-stage catalyst bed ammonia synthesis tower, n equals 1; when the second synthesis tower 2 is a single-stage catalyst bed ammonia synthesis tower, m equals 0; when the first synthesis tower 1 is a two-stage catalyst bed ammonia synthesis tower, n equals 2; when the second synthesis tower 2 is a two-stage catalyst bed ammonia synthesis tower, m equals 1; and so on, when the first synthesis tower 1 and / or the second synthesis tower 2 are multi-stage catalyst bed ammonia synthesis towers, so that the system can meet the ammonia synthesis load requirements of different types of synthesis towers.
[0044] Optionally, the pipeline system 4 includes an exhaust pipeline 42. The exhaust pipeline 42 on the second synthesis tower 2 is connected to the corresponding reaction gas output terminal 72. The exhaust pipeline 42 on the first synthesis tower 1 is connected to the corresponding reaction gas output terminal 72 or to the fourth main pipeline 46. The connection point is located on the pipeline between the third main valve 57 and the corresponding reaction gas output terminal 72. The valve system 5 includes an exhaust valve 58 installed in the exhaust pipeline 42 on the first synthesis tower 1. The raw material supply source 3 includes a heat exchanger 31 and a total input line 32. The pipeline system 4 includes a total output line 33. The heat exchanger 31 has a first channel and a second channel. One end of the first channel is connected to the total input line 32, and the other end of the first channel is connected to both the first main pipeline 43 and the second main pipeline 44. One end of the second channel is connected to the total output line 33, and the other end of the second channel is connected to both exhaust pipelines 42.
[0045] In this embodiment, the discharge valve 58 is used to control whether the exhaust gas in the discharge pipeline 42 in the first synthesis tower 1 is directly discharged. When the discharge valve 58 is open, the exhaust gas is directly discharged; when the discharge valve 58 is closed, the exhaust gas can enter the second synthesis tower 2 from the open third main valve 57 to provide hot standby for the second synthesis tower 2, which facilitates the switching of the system's operating conditions.
[0046] A control method, based on the aforementioned dual-tower dynamic series-parallel flexible ammonia synthesis system, includes the following steps: S10a, controlling the valve system 5 to connect the second pipeline group, the third pipeline group, and the fourth pipeline group, while disconnecting the first pipeline group.
[0047] In this embodiment, connecting the second pipeline group, the third pipeline group, and the fourth pipeline group while disconnecting the first pipeline group can meet the low-load operating conditions of the system. This allows the high-temperature reaction gas from the first synthesis tower 1 to insulate the catalytic bed in the second synthesis tower 2, maintaining the catalytic temperature of the second synthesis tower 2 as much as possible. Consequently, the dual-tower system can achieve a wider load range while consuming less energy, adjusting faster, and having a higher system responsiveness when transitioning from low-load to high-load conditions.
[0048] Optionally, step S10a includes controlling the first main valve 52 in the control valve system 5 to close, controlling the third valve 55 on the second pipeline 441 connected to the tower wall gas inlet 63 to open, controlling the remaining third valves 55 to close, controlling the supplement valve 51 to close, controlling the second main valve 56 to open, controlling the first valve 53 to close, controlling the second valve 54 to open, controlling the discharge valve 58 to close, and controlling the third main valve 57 to open.
[0049] As will be understood by those skilled in the art, a synthesis tower includes tower internals and tower shell. The tower internals are located inside the tower shell, and an annular gap is formed between the tower internals and the tower shell. The tower internals are a collective term for the core components used in the process of synthesizing ammonia.
[0050] In this embodiment, by controlling a specific valve system, the system can maintain a low-load operating condition. During this process, the third valve 55 on the second pipeline 441, which is connected to the tower wall gas inlet 63, is opened, allowing the gas to enter the tower wall gas inlet 63 of the second synthesis tower 2. The tower wall gas flows into the annular gap between the tower internals and the tower shell of the second synthesis tower 2 and carries away the heat on the high-temperature tower internals wall of the second synthesis tower 2 through heat transfer. A large amount of heat on the high-temperature tower internals wall of the second synthesis tower 2 is carried out of the second synthesis tower 2 by the flowing tower wall gas, while a small amount of heat on the high-temperature tower internals wall of the second synthesis tower 2 is transferred to the tower shell of the second synthesis tower 2 through the heated tower wall gas. Meanwhile, the high-temperature reaction gas from the first synthesis tower 1, after exiting from the reaction gas outlet 72, enters the second synthesis tower 2 through the opened third main valve 57 to heat the catalyst bed inside the second synthesis tower 2. During this heating process, the high-temperature reaction gas in the tower mainly transfers heat to the tower internals of the second synthesis tower 2 through forced convection heat transfer. Due to the high temperature of the reaction gas, the temperature of the tower internals wall of the second synthesis tower 2 will be very high. Therefore, if no gas is introduced into the tower wall, the gap between the internal components and the outer shell of the second synthesis tower 2 is filled with stagnant gas. In this state, heat transfer between the internal components, the stagnant gas, and the outer shell is mainly through natural convection and conduction. All the heat transferred outward from the high-temperature internal components of the second synthesis tower 2 will be transferred to the outer shell, resulting in a very high maximum temperature for the outer shell. Therefore, the material used to manufacture the outer shell of the second synthesis tower 2 must have good heat resistance, which leads to a higher material cost. However, by first introducing gas into the second synthesis tower 2... The method of introducing gas into the annular gap between the outer shell and the inner shell of the second synthesis tower 2 through the tower wall gas inlet 63 allows the low-temperature gas to carry away the heat on the high-temperature inner wall of the second synthesis tower 2 through the heat transfer tube when the inner wall of the second synthesis tower 2 is heated, and to carry away a large amount of heat out of the second synthesis tower 2. This reduces the heat transferred to the outer shell of the second synthesis tower 2, thereby reducing the maximum temperature value of the outer shell of the second synthesis tower 2 being heated. As a result, the second synthesis tower 2 can be made of materials with relatively low heat resistance. Due to this different control method, the overall cost of the ammonia synthesis system is greatly reduced.
[0051] A control method, based on the aforementioned dual-tower dynamic series-parallel flexible ammonia synthesis system, includes the following steps: S10b, control valve system 5, to connect the first pipeline group, connect the second pipeline group, disconnect the third pipeline group, and disconnect the fourth pipeline group.
[0052] In this embodiment, connecting the first pipeline group, connecting the second pipeline group, disconnecting the third pipeline group, and disconnecting the fourth pipeline group allows the first synthesis tower 1 and the second synthesis tower 2 to be supplied with gas and loaded independently, thereby achieving two possible operating conditions: one is the start-up operating condition, in which the first synthesis tower 1 and the second synthesis tower 2 gradually increase their load; the other is the high-load operating condition, in which both the first synthesis tower 1 and the second synthesis tower 2 are used for the gas-inlet catalytic synthesis of ammonia. Specific Implementation Method 1
[0054] Operating conditions: The valve system 5 controls the opening of the first main valve 52, the opening of the first valve 53, and the opening of the third valve 55 on the pipeline connecting the second synthesis tower 2 to the heating device 8. This allows the raw material supply source 3 to simultaneously supply gas to both the first and second synthesis towers 1 and 2. The gas is then heated to the required operating temperature by the heating device 8 and enters the corresponding synthesis tower. When the catalyst bed temperature is below the catalyst activation temperature, the catalyst bed temperature is increased. When the catalyst bed temperature is reached, the ammonia synthesis reaction begins. As the ammonia synthesis reaction proceeds in the first synthesis tower 1 / second synthesis tower 2, the corresponding heating device 8 is gradually shut off. When the first synthesis tower 1 / second synthesis tower 2 reaches self-heating equilibrium, the corresponding heating device 8 is completely shut off. Specific Implementation Method Two Low load condition: Control the first main valve 52 to close, control the third valve 55 on the second pipeline 441 connected to the tower wall gas inlet 63 to open, so that the gas in the raw material supply 3 enters from the tower wall gas inlet 63 on the second synthesis tower 2 and controls the temperature of the second synthesis tower 2. Control the remaining third valve 55 to close, control the supplement valve 51 to close, control the second main valve 56 to open, control the first valve 53 to close, control the second valve 54 to open, so that the gas discharged from the second synthesis tower 2 enters the first synthesis tower 1 and fully contacts and reacts with the catalyst bed in the first synthesis tower 1. Control the discharge valve 58 to close, control the third main valve 57 to open, so that the reaction gas discharged from the first synthesis tower 1 re-enters the catalyst bed in the second synthesis tower 2, keeps the catalyst bed in the second synthesis tower 2 warm, and finally discharges. Specific Implementation Method 3 High load condition: Control the first main valve 52 to open, the first valve 53 to close, the second valve 54 to open, control the third valve 55 of the pipeline where the heating device 8 of the second synthesis tower 2 is located to close, and the remaining third valves 55 to open, so that the gas from the raw material supply source 3 can fully enter the first synthesis tower 1 and the second synthesis tower 2 and react fully with the corresponding catalyst bed. Control the second main valve 56 to close, control the supplement valve 51 to open, so that the gas used to control the temperature of the second synthesis tower 2 can re-enter the second synthesis tower 2 and react with the catalyst bed. Control the third main valve 57 to close, so that the reaction gas discharged from the first synthesis tower 1 and the reaction gas discharged from the second synthesis tower 2 can merge and exchange heat with the gas inlet through the heat exchanger 31 to increase the gas inlet temperature. Specific Implementation Method Four In one possible implementation, the raw material supply source 3 further includes a first compressor installed on the main input line 32, and a cold exchanger, cooler, ammonia cooler, ammonia separator and ammonia flash evaporator installed on the main output line 33. A first connecting pipeline is also provided between the cold exchanger and the main input line 32, and a second compressor is installed on the first connecting pipeline. The connection point between the first connecting pipeline and the main input line 32 is located between the first compressor and the heat exchanger 31, and a second connecting pipeline is also provided between the ammonia separator and the cold exchanger. When the reaction gas is discharged, the two outlet gases merge and go to heat exchanger 31 for heat exchange. After entering the cooler for cooling, it exchanges heat with the shell-side cold gas in the cold exchanger. Then it enters the ammonia cooler, and after ammonia separation in the ammonia separator, the gas phase goes to the cold exchanger to recover the cooling capacity. Then it goes to the second compressor for the next cycle. The liquid ammonia separated by the ammonia separator is sent to the ammonia flash tank after depressurization. The flash vapor in the ammonia flash tank is sent to the outside area for treatment, and the product liquid ammonia is sent to the outside area.
[0055] When the load decreases from a high load condition to a low load condition: the total amount of gas entering the tower is gradually reduced by controlling the intake of fresh gas and the second compressor. At the same time, the third valve 55 connected to the branch gas input terminal 62 on the second synthesis tower 2 is gradually closed to reduce the amount of gas entering the second synthesis tower 2, thereby reducing the load. When the load decreases to a certain level, the second main valve 56 and the third main valve 57 are gradually opened, and the supplement valve 51, the first main valve 52 and the discharge valve 58 are gradually closed as the load decreases.
[0056] When transitioning from a low-load to a high-load condition: If the catalyst temperature in the second synthesis tower 2 has not reached its activation temperature at the initial low-load state of the transition from low to high load, the heating device 8 needs to be turned on to heat the gas entering the catalyst bed of the second synthesis tower 2, thus raising the catalyst temperature to its activation temperature. The total amount of gas entering the tower is gradually increased by controlling the fresh gas intake and the second compressor. Simultaneously, the third valve 55, connected to the branch gas input terminal 62 on the second synthesis tower 2, is gradually opened to increase the gas flow into the second synthesis tower 2, thereby increasing the load. When the load increases to a certain level, the second main valve 56 and the third main valve 57 are gradually closed, while the replenishment valve 51, the first main valve 52, and the discharge valve 58 are gradually opened as the load increases.
[0057] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A flexible ammonia synthesis system with dual-tower dynamic series-parallel connection, characterized in that, It includes a first synthesis tower (1), a second synthesis tower (2), and a raw material supply (3); Both the first synthesis tower (1) and the second synthesis tower (2) have input systems and output systems; The pipeline system (4) includes a first pipeline group located between the raw material supply source (3) and the input system of the first synthesis tower (1), a second pipeline group located between the raw material supply source (3) and the input system of the second synthesis tower (2), a third pipeline group located between the input system of the first synthesis tower (1) and the output system of the second synthesis tower (2), and a fourth pipeline group located between the output system of the first synthesis tower (1) and the input system of the second synthesis tower (2). The fourth pipeline group is not connected to the third pipeline group in the second synthesis tower (2). The valve system (5) is used to control the opening and closing of the corresponding pipelines in the pipeline system (4). The valve system (5) has at least a first operating condition and a second operating condition. Under the first operating condition, the first pipeline group is connected, the second pipeline group is connected, the third pipeline group is disconnected, and the fourth pipeline group is disconnected. In the second operating condition, the second pipeline group is connected, the third pipeline group is connected, the fourth pipeline group is connected, and the first pipeline group is disconnected.
2. The dual-tower dynamic series-parallel flexible ammonia synthesis system according to claim 1, characterized in that, The maximum load of the first synthesis tower (1) is lower than the maximum load of the second synthesis tower (2).
3. The dual-tower dynamic series-parallel flexible ammonia synthesis system and control method according to claim 2, characterized in that, The ratio between the maximum load of the first synthesis tower (1) and the maximum load of the second synthesis tower (2) is between 0.25 and 0.
5.
4. The dual-tower dynamic series-parallel flexible ammonia synthesis system according to claim 2, characterized in that, The input system of the second synthesis tower (2) includes a tower wall gas input terminal (63); the output system of the second synthesis tower (2) includes a tower wall gas output terminal (71), the tower wall gas input terminal (63) is connected to the tower wall gas output terminal (71) inside the second synthesis tower (2), the input system of the second synthesis tower (2) also includes a supplementary input terminal (64), a supplementary pipeline (41) is provided between the tower wall gas output terminal (71) and the corresponding supplementary input terminal (64), a supplementary valve (51) is provided in the supplementary pipeline (41), and the valve system (5) in the first operating condition opens the supplementary valve (51) to connect the supplementary pipeline (41); the valve system (5) In the second operating condition, the supplement valve (51) is closed, causing the supplement pipeline (41) to be disconnected. The input system also includes a heating gas input terminal (61) and a branch gas input terminal (62). The heating gas input terminal (61) is connected to a heating device (8) through a pipeline. The output system also includes a reaction gas output terminal (72). In the first synthesis tower (1), the heating gas input terminal (61) and the branch gas input terminal (62) are connected to the corresponding reaction gas output terminal (72). In the second synthesis tower (2), the heating gas input terminal (61), the supplement input terminal (64), and the branch gas input terminal (62) are connected to the corresponding reaction gas output terminal (72).
5. A dual-tower dynamic series-parallel flexible ammonia synthesis system according to claim 4, characterized in that, The first pipeline group includes a first main pipeline (43) connected to the raw material supply source (3) and a first pipeline (431). One end of the first main pipeline (43) is connected to one end of all the first pipelines (431). The heating device (8) and the branch gas input end (62) on the first synthesis tower (1) are both connected to one of the first pipelines (431). The valve system (5) includes a first main valve (52) installed on the first main pipeline (43), a first valve (53) installed on the first pipeline (431) connected to the heating device (8), and a second valve (54) installed on the other first pipelines (431). The second pipeline group includes a second main pipeline (44) and a second pipeline (441) connected to the raw material supply source (3). One end of the second main pipeline (44) is connected to one end of all the second pipelines (441). The heating device (8), the branch gas input end (62) and the tower wall gas input end (63) on the second synthesis tower (2) are all connected to one of the second pipelines (441). The valve system (5) includes a third valve (55) installed on each second pipeline (441). The third pipeline group includes a third main pipeline (45), one end of which is connected to the tower wall gas output end (71) of the second synthesis tower (2), and the other end of which is connected to the first main pipeline (43). The connection point is located between the first main valve (52) and the first pipeline (431). The valve system (5) includes a second main valve (56) installed on the third main pipeline (45). The fourth pipeline group includes a fourth main pipeline (46), one end of which is connected to the reaction gas output end (72) of the first synthesis tower (1), and the other end of which is connected to the heating device (8) on the second synthesis tower (2). The connection point is located on the pipeline between the input end of the heating device (8) and the corresponding third valve (55). The valve system (5) includes a third main valve (57) installed on the fourth main pipeline (46).
6. The dual-tower dynamic series-parallel flexible ammonia synthesis system according to claim 4, characterized in that, The number of branch gas input terminals (62) on the first synthesis tower (1) is n, and the number of branch gas input terminals (62) on the second synthesis tower (2) is m, where n is an integer not less than 1 and m is an integer not less than 0.
7. A dual-tower dynamic series-parallel flexible ammonia synthesis system according to claim 5, characterized in that, The pipeline system (4) includes an exhaust pipeline (42). The exhaust pipeline (42) on the second synthesis tower (2) is connected to the corresponding reaction gas output end (72). The exhaust pipeline (42) on the first synthesis tower (1) is connected to the corresponding reaction gas output end (72) or to the fourth main pipeline (46). The connection point is located on the pipeline between the third main valve (57) and the corresponding reaction gas output end (72). The valve system (5) includes an exhaust system installed in the exhaust pipeline (42) on the first synthesis tower (1). Valve (58); Raw material supply source (3) includes heat exchanger (31) and main input line (32), the pipeline system (4) includes main output line (33), the heat exchanger (31) has a first channel and a second channel, one end of the first channel is connected to the main input line (32), and the other end of the first channel is connected to both the first main pipeline (43) and the second main pipeline (44); one end of the second channel is connected to the main output line (33), and the other end of the second channel is connected to both the two discharge pipelines (42).
8. A control method, based on a dual-tower dynamic series-parallel flexible ammonia synthesis system as described in any one of claims 1-7, characterized in that, The steps include: S10a, controlling the valve system (5) to connect the second pipeline group, the third pipeline group, the fourth pipeline group, and disconnect the first pipeline group.
9. A control method, based on a dual-tower dynamic series-parallel flexible ammonia synthesis system as described in any one of claims 1-7, characterized in that, The process includes the following steps: S10b, controlling the valve system (5) to connect the first pipeline group, connect the second pipeline group, disconnect the third pipeline group, and disconnect the fourth pipeline group.
10. The control method according to claim 8, characterized in that, Step S10a includes closing the first main valve (52) in the control valve system (5), opening the third valve (55) on the second pipeline (441) connected to the tower wall gas input end (63), closing the remaining third valves (55), closing the supplementary valve (51), opening the second main valve (56), closing the first valve (53), opening the second valve (54), closing the discharge valve (58), and opening the third main valve (57).