Wide-load follow-up flexible green ammonia synthesis system

Abstract

The invention relates to a wide-load follow-up flexible green ammonia synthesis system which comprises a compression unit, a synthesis ammonia and heat recovery unit and a cooling separation unit. According to the wide-load follow-up flexible green ammonia synthesis system, hydrogen load control and adjustment are matched with hydrogen flow adjustment and control of the compression unit, and tower inlet flow adjustment and control of the synthesis ammonia and heat recovery unit; the process parameters such as load, pressure, temperature and the like of the system are quickly responded and repaired, temperature and pressure fatigue of equipment is prevented, the flow of gas entering a tower is adjusted according to the flow of raw material hydrogen, the flow of gas passing through a catalyst bed fluctuates along with the flow of the raw material hydrogen and moves along with hydrogen, the operation flexibility is within the range of 5-125%, and the pressure of the system is kept relatively stable.

Description

Technical Field

[0001] This application relates to the field of green ammonia synthesis technology, and more specifically, to a wide-load follow-up flexible green ammonia synthesis system. Background Technology

[0002] In the field of new energy, turning wind, solar and green electricity into a new energy source that can be stored and transported, as well as fertilizers and chemical raw materials, is in line with the industrial policy of carbon neutrality and carbon balance, and has a wide range of application scenarios.

[0003] Currently, traditional ammonia synthesis generally uses natural gas or coal as raw materials, and the operational flexibility of ammonia synthesis is generally 50-110%. However, for green ammonia generated by wind and solar power, if ammonia synthesis still maintains an operational flexibility of 50-110%, a large amount of energy storage and hydrogen storage will be required. This not only involves huge investment, but also brings safety hazards due to the large number of hydrogen storage tanks.

[0004] Based on the above technical risks and investment economic factors, green ammonia processes with design concepts such as flexible ammonia synthesis, dynamic ammonia synthesis, and multi-stable ammonia synthesis have been introduced at home and abroad. These processes emphasize the improvement of automatic control systems, but neglect the essential improvement of the combination of ammonia synthesis reaction principle and process. The process is basically the same as the traditional ammonia synthesis process.

[0005] In the control loop of a traditional ammonia synthesis compressor, the operation of traditional ammonia synthesis is relatively stable with little fluctuation in the elasticity range, and its control is relatively simple. Generally, the compressor manufacturer can achieve an operational elasticity of 50-110%. In order to adapt to the operational elasticity of green ammonia, some domestic manufacturers have proposed the control concept of "multi-steady state" or "segmented control", but the process has not been changed.

[0006] In traditional ammonia synthesis systems, classic and reliable processes are only suitable for applications with small load fluctuations and infrequent fluctuations. For green ammonia processes, if the traditional ammonia synthesis process is still used without modification, it will lead to "cross-temperature" stress in the synthesis tower and fatigue stress caused by repeated fluctuations in pressure and temperature, posing a significant threat to the stable and safe operation of the plant.

[0007] In traditional ammonia synthesis towers and heat recovery processes, the catalyst bed can be designed with various structures, such as 1-stage, 2-stage, 3-stage, and 4-stage, depending on factors such as production capacity and gas conditions. For large-scale gray ammonia plants, i.e., traditional chemical feedstock ammonia synthesis plants, the catalyst bed structure generally adopts a radial flow structure, while small-scale plants typically use a mixed structure of axial and radial sections. To maximize steam production, a bottom heat exchanger is generally not installed at the synthesis tower outlet to recover heat; only small-scale plants and reactors with low reaction efficiency are equipped with a bottom heat exchanger.

[0008] For the ammonia green process, due to large load fluctuations and the possibility of prolonged low-load production, it is also prone to thermal stress caused by "cross-temperature" and repeated temperature changes. Furthermore, when the catalyst bed adopts an axial flow or ordinary radial flow structure, the catalyst is highly susceptible to accumulation and pulverization under repeated fluctuations in gas flow rate, temperature, and pressure.

[0009] For the reasons mentioned above, domestic synthetic ammonia plants generally only promise a load fluctuation range of 30-110%, requiring the configuration of large amounts of hydrogen and energy storage. The investment and operating costs of green ammonia remain high. With unclear certification and sales channels for green ammonia, the investment and production costs of green ammonia and gray ammonia are significantly different, which restricts the further promotion of green ammonia technology in China and slows down the "dual carbon" process. There are many projects approved and initiated in China, but the proportion of projects actually constructed is too small.

[0010] Given the uncertainty surrounding the premium for green ammonia, in order to further reduce investment and operating costs and enhance the competitiveness of green ammonia over gray ammonia in terms of investment and operating costs, there is an urgent need to develop a flexible green ammonia process that is fast-responding, safe, reliable, and has an operational flexibility of 5–125% with wide load range. Summary of the Invention

[0011] The purpose of this application is to provide a wide-load-following flexible green ammonia synthesis system, which features rapid response, safety and reliability, and low investment cost. It can also greatly expand the range of operational flexibility, making the operational flexibility reach 5-125%, and solve the problems of small load adjustment range, slow fluctuation response, and poor stable operation in the application of existing traditional ammonia synthesis processes in green ammonia processes.

[0012] To achieve the above objectives, the present invention provides a wide-load follow-up flexible green ammonia synthesis system, comprising: a compression unit, an ammonia synthesis and heat recovery unit, and a cooling and separation unit; The compression unit includes a hydrogen inlet pipeline, and a hydrogen flow regulation circuit is provided on the hydrogen inlet pipeline. The ammonia synthesis and heat recovery unit includes an ammonia synthesis tower and an external electric furnace. The ammonia synthesis tower is connected to a circulating gas inlet pipeline. The circulating gas inlet pipeline includes a main circulating gas inlet pipeline, as well as a parallel branch circulating gas inlet tower pipeline and a circulating gas bypass pipeline. The circulating gas bypass pipeline is connected to the cooling and separation unit. A bypass flow regulation circuit is provided on the circulating gas bypass pipeline, and a circulating gas pressure and flow control circuit is provided on the circulating gas inlet main pipeline. The hydrogen flow regulation circuit and the bypass flow regulation circuit are electrically connected to the circulating gas pressure and flow control circuit. The circulating gas pressure and flow control circuit can receive wind and solar forecasts converted into hydrogen flow and control the actual required gas flow into the tower according to the different hydrogen flow and circulating gas flow received. The external electric furnace is connected to a thermally stabilized gas pipeline, and a temperature and flow control loop is provided between the thermally stabilized gas pipeline and the ammonia synthesis tower. The temperature and flow control loop can control the flow rate of the circulating gas in the thermally stabilized gas pipeline according to the received hydrogen flow rate. The ammonia synthesis tower is equipped with multiple catalyst beds, which adopt a suspended radial gas distribution inlet. Cooling devices are installed between different catalyst beds, and a bottom heat exchanger is installed at the bottom of the bottom catalyst bed.

[0013] In an optional embodiment, the compression unit includes a compressor compression section, a compressor circulation section, an intercooler, and a compressor system buffer unit, wherein the compressor system buffer unit includes a buffer tank or a buffer tube. The compressor's compression section includes a nitrogen inlet pipe and a hydrogen inlet pipe. A nitrogen flow rate regulating circuit is provided on the nitrogen inlet pipe, and a proportional regulation control circuit is provided between the nitrogen flow rate regulating circuit and the hydrogen flow rate regulating circuit.

[0014] In an optional embodiment, the nitrogen inlet pipeline and the hydrogen inlet pipeline merge to form the supplementary gas inlet pipeline of the compressor compression section. The buffer outlet pipeline of the compressor system buffer unit is connected to the supplementary gas inlet pipeline, and a buffer outlet bypass pipeline is provided on the buffer outlet pipeline. A supplementary gas pressure and flow control loop is provided between the buffer outlet bypass pipeline, the buffer outlet pipeline, and the supplementary gas inlet pipeline.

[0015] In an optional embodiment, the compressor system buffer unit is further connected to a buffer intake pipe, a buffer intake bypass pipe is provided on the buffer intake pipe, and a buffer intake pressure and flow control circuit is provided between the buffer intake bypass pipe and the buffer intake pipe.

[0016] In an optional embodiment, a circulating gas inlet flow detection unit is provided on the circulating gas inlet pipeline, and the circulating gas inlet flow detection unit is electrically connected to the circulating gas pressure and flow control loop.

[0017] In an optional embodiment, a first inlet gas pipeline, a second inlet gas pipeline, a third inlet gas pipeline, and a fourth inlet gas pipeline are provided between the circulating gas inlet pipeline and the ammonia synthesis tower. The third gas inlet pipeline is located upstream of the external electric furnace, and an internal electric furnace is installed at the top of the ammonia synthesis tower. The first gas inlet pipeline and the third gas inlet pipeline are respectively connected to the internal electric furnace. The first inlet gas pipeline includes an inlet gas pipeline for heating inside the tower and an inlet gas pipeline for heating outside the tower, which serves as the thermally stabilized gas pipeline.

[0018] In an optional embodiment, temperature regulation loops are respectively provided between the heating gas inlet pipe and the ammonia synthesis tower, between the second gas inlet pipe and the ammonia synthesis tower, and between the third gas inlet pipe and the ammonia synthesis tower.

[0019] In an optional embodiment, the ammonia synthesis tower is connected to a synthetic ammonia outlet pipeline, the fourth inlet gas pipeline serves as the start-up gas inlet pipeline, and a temperature regulation loop is provided between the synthetic ammonia outlet pipeline and the fourth inlet gas pipeline.

[0020] In an optional embodiment, the temperature regulation loop includes an inlet gas temperature controller, which is configured to correspond to different sections of the catalyst bed.

[0021] In an optional embodiment, the connection point between the external heating gas pipeline and the ammonia synthesis tower is arranged corresponding to the location of the catalyst bed in the top section.

[0022] This invention provides rapid response and repair to process parameters such as load, pressure, and temperature of the system through hydrogen load control and regulation, along with hydrogen flow regulation and control in the compression unit and inlet flow regulation and control in the ammonia synthesis and heat recovery unit. This prevents equipment fatigue due to temperature and pressure issues. Furthermore, it adjusts the inlet gas flow according to the feed hydrogen flow rate, and the gas flow rate in the catalyst bed fluctuates with the feed hydrogen flow rate, ensuring that the system moves with the hydrogen supply. This allows for an operational flexibility of 5–125%, maintaining relatively stable system pressure.

[0023] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the system structure and control adjustment of the compression unit in this application; Figure 2 This is a schematic diagram of the system structure and control regulation of the ammonia synthesis and heat recovery unit and the cooling separation unit in this application; Figure 3 This is a schematic diagram of the process for heat recovery of the catalyst bed in the ammonia synthesis tower in this application.

[0026] icon: 11-Compressor compression section; 12-Compressor circulation section; 13-Intercooler; 14-Compressor system buffer unit; 111-Nitrogen inlet line; 112-Hydrogen inlet line; 113-Make-up gas inlet line; 114-Buffer outlet line; 115-Buffer outlet bypass line; 116-Buffer inlet line; 117-Buffer inlet bypass line. 21-Ammonia synthesis tower; 21a-First stage catalyst bed; 21b-Second stage catalyst bed; 21c-Third stage catalyst bed; 22-Steam generator; 23-Boiler feedwater heater; 24-Heat exchanger; 25-External electric furnace; 26-Internal electric furnace; 27-Bottom heat exchanger; 211 - Main inlet pipe for circulating gas; 212 - Inlet pipe for circulating gas into the tower; 213 - Short-circuit pipe for circulating gas; 214 - First inlet pipe for the tower; 214a - Inlet pipe for internal heating of the tower; 214b - Inlet pipe for external heating of the tower; 215 - Second inlet pipe for the tower; 216 - Third inlet pipe for the tower; 217 - Fourth inlet pipe for the tower; 218 - Outlet pipe for synthetic ammonia; 31-Water cooler; 32-Cool exchanger; 33-Primary ammonia cooler; 34-Secondary ammonia cooler; 35-Ammonia classifier; 36-Ammonia flash tank; 10-Nitrogen flow regulation loop; 20-Hydrogen flow regulation loop; 30-Proportional regulation control loop; 40-Make-up gas pressure and flow control loop; 50-Buffer inlet gas pressure and flow control loop; 60-Borrow flow regulation loop; 70-Circulating gas pressure and flow control loop; 80-Circulating gas inlet flow detection unit; 90-Temperature and flow control loop; 100-Temperature regulation loop; 110-Inlet gas temperature controller. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" 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 connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0030] The wide-load follow-up flexible green ammonia synthesis system in this application mainly involves a green ammonia synthesis process with large fluctuations in the flow rate and composition of the raw material gas (mainly hydrogen). Specifically, it is a green ammonia synthesis process based on the raw material hydrogen being green hydrogen produced by wind and solar power generation and water electrolysis, which is then mixed with green nitrogen to produce synthetic ammonia.

[0031] See Figures 1-3 The wide-load follow-up flexible green ammonia synthesis system in this application includes: a compression unit, an ammonia synthesis and heat recovery unit, and a cooling and separation unit; The compression unit includes a hydrogen inlet pipe 112, and a hydrogen flow regulating circuit 20 is provided on the hydrogen inlet pipe 112. The ammonia synthesis and heat recovery unit includes an ammonia synthesis tower 21 and an external electric furnace 25. The ammonia synthesis tower 21 is connected to a circulating gas inlet pipeline. The circulating gas inlet pipeline includes a main circulating gas inlet pipeline 211, as well as a parallel branch circulating gas inlet tower pipeline 212 and a circulating gas bypass pipeline 213. The circulating gas bypass pipeline 213 is connected to the cooling and separation unit. A bypass flow regulation circuit 60 is provided on the circulating gas bypass pipeline 213, and a circulating gas pressure and flow control circuit 70 is provided on the circulating gas inlet main pipeline 211. The hydrogen flow regulation circuit 20 and the bypass flow regulation circuit 60 are electrically connected to the circulating gas pressure and flow control circuit 70 respectively. The circulating gas pressure and flow control circuit 70 can receive wind and solar forecasts converted into hydrogen flow and control the actual required gas flow into the tower according to the different hydrogen flow and circulating gas flow received. The external electric furnace 25 is connected to a heat-stabilized gas pipeline. A temperature and flow control loop 90 is provided between the heat-stabilized gas pipeline and the ammonia synthesis tower 21. The temperature and flow control loop 90 can control the flow rate of the circulating gas in the heat-stabilized gas pipeline according to the received hydrogen flow rate. The ammonia synthesis tower 21 is equipped with multiple catalyst beds. The catalyst beds adopt a suspended radial gas distribution inlet form. Cooling devices are provided between different catalyst beds. A bottom heat exchanger 27 is provided at the bottom of the bottom catalyst bed.

[0032] The regulation in this application mainly involves a hydrogen load control regulation system. The regulation loop refers to the installation of a flow regulating valve and a flow or temperature controller on the pipeline. The opening degree of the flow regulating valve is controlled by the flow or temperature signal fed back by the flow or temperature controller.

[0033] The pressure-flow control loop and temperature-flow control loop 90 refer to the installation of a flow regulating valve or temperature regulating valve and a pressure or temperature controller on the pipeline. The opening degree of the flow regulating valve or temperature regulating valve is controlled by the pressure or temperature signal fed back by the pressure or temperature controller. In other words, the definition of the control loop involves the combination of monitoring different parameters.

[0034] The proportional regulation control loop 30 specifically refers to the proportional control between the flow rates of hydrogen and nitrogen, used to adjust the composition of the supplementary gas.

[0035] From the perspective of the system as a whole, it constitutes the hydrogen flow regulation and control of the compression unit involved in the hydrogen load control and regulation system, and the inlet flow regulation and control of the ammonia synthesis and heat recovery unit.

[0036] By setting a hydrogen flow regulation loop 20 on the hydrogen inlet pipeline 112, hydrogen flow regulation control of the compression unit can be formed.

[0037] By setting up a bypass flow regulation loop 60 on the bypass pipeline 213 and a bypass pressure and flow control loop 70 on the bypass pipeline 211, the inlet flow rate of the ammonia synthesis tower 21 can be regulated and controlled.

[0038] Furthermore, by electrically connecting the hydrogen flow regulation circuit 20 and the bypass flow regulation circuit 60 to the circulating gas pressure and flow control circuit 70, a pressure stabilization system for the green ammonia process can be formed.

[0039] The hydrogen flow regulation loop 20, the bypass flow regulation loop 60, and the circulating gas pressure and flow control loop 70 together constitute the pressure stabilization system of the green ammonia process system.

[0040] The circulating gas pressure and flow control loop 70 can receive wind and solar forecasts and convert them into hydrogen flow, and control the actual required gas flow into the tower according to the different hydrogen flow and circulating gas flow received.

[0041] Specifically, the circulating gas pressure and flow control loop 70 is the core of the pressure stabilization system, which is implemented by the PIC001 pressure control system. The PIC001 pressure control system includes the calculated value of hydrogen flow into the system FY1 (H2), the calculated value of hydrogen flow feedforward based on wind and solar forecasts FY2 (H2), the total circulating gas volume into the tower FY3, and the system bypass gas volume FY4.

[0042] The actual required gas flow rate FY5 for the tower is calculated by the pressure control of PIC001 under different hydrogen flow rates. The actual required gas flow rate FY5 is calculated by subtracting the total circulating gas flow rate FY3 from the system bypass gas flow rate FY4, which can be controlled by the system bypass valve FV001.

[0043] The pressure stabilization system of the green ammonia process makes full use of the dynamic balance between the actual required gas flow rate and the fixed catalyst quantity. Through dynamic calculation and continuous simulation, the rise and fall of the PIC001 pressure is kept in a smooth state and can be adjusted within the range of 10-110% load, with pressure fluctuation not exceeding 20%, so as to avoid the occurrence of pressure fatigue conditions.

[0044] In addition to the pressure stabilization system described above, the green ammonia synthesis system in this application also includes a temperature stabilization system. The electric furnace 26 inside the ammonia synthesis tower 21, the electric furnace 25 outside the tower, and the temperature and flow control loop 90 set between the heat stabilization gas pipeline and the ammonia synthesis tower 21 constitute the basis of the control system.

[0045] Specifically, the temperature and flow control loop 90 is the core of the temperature stabilization system, which is implemented by the TIC001 temperature control system. The external electric furnace 25 and the internal electric furnace 26 complement each other to form a dual guarantee of heat balance, so as to adapt to the rapid reduction of load and extremely low load.

[0046] When the load decreases rapidly, reaching a decrease of 5% per minute, the external electric furnace 25 or the internal electric furnace 26 can quickly provide the heat load of the heat stabilizing gas; when the load decreases to 10%, the external electric furnace 25 or the internal electric furnace 26 can quickly start to provide a heat source for supply, and can also operate normally at 5% load.

[0047] The opening degree of the valve for the heat-stabilized gas entering the electric furnace 25 outside the tower is controlled by the temperature controller TC of the gas entering the tower in the temperature and flow control loop 90. Based on the temperature of the heat-stabilized gas entering the tower detected by TC, the calculated value of the hydrogen flow rate entering the system FY1 (H2), and the feedforward calculated value of the hydrogen flow rate converted from wind and solar power prediction FY2 (H2), the opening degree of the valve TV001 for the gas to be heated is calculated.

[0048] From the perspective of catalyst bed optimization, in the ammonia synthesis tower 21 of the ammonia synthesis and heat recovery unit, the catalyst bed includes a multi-stage catalyst bed consisting of a first-stage catalyst bed 21a, a second-stage catalyst bed 21b, and a third-stage catalyst bed 21c. The catalyst bed can be designed into various catalyst bed structures such as 1-stage, 2-stage, 3-stage, and 4-stage according to factors such as production capacity and gas conditions.

[0049] Compared to the existing traditional gray ammonia synthesis process, the catalyst bed structure adopts a suspended radial gas distribution structure, which forms a suspended radial gas distribution inlet form, giving the catalyst a certain buoyancy, preventing the catalyst from being squeezed or pulverized, and allowing for more complete contact between the gas and the catalyst, resulting in higher reaction efficiency.

[0050] An upper interlayer heat exchanger or cold pipes, cold quench gas, or other gas cooling measures are installed between the first catalyst bed 21a and the second catalyst bed 21b; a lower interlayer heat exchanger or cold pipes, cold quench gas, or other gas cooling measures are installed between the second catalyst bed 21b and the third catalyst bed 21c; by installing a bottom heat exchanger 27 at the lower outlet of the bottom catalyst bed (shown as the third catalyst bed 21c in the attached diagram), heat can be recovered and the temperature of the entire tower can be stabilized.

[0051] By introducing the heat-stabilizing gas into the electric furnace 25 outside the tower into the catalyst bed located at the top, as shown in the attached figure, the inlet temperature of the synthesis tower can be further stabilized.

[0052] It should be noted that in the attached diagram, FC, PC, and TC are flow controllers, pressure controllers, and temperature controllers that can detect and regulate, respectively, while TV and FV are temperature control valves and flow control valves, respectively, which can participate in the control of pipeline material flow.

[0053] The following section provides a further explanation of the control angles for different units.

[0054] The compression unit includes a compressor compression section 11, a compressor circulation section 12, an intercooler 13, and a compressor system buffer unit 14, which includes a buffer tank or a buffer tube. The compressor compression section 11 has an intake pipeline including a nitrogen intake pipeline 111 and a hydrogen intake pipeline 112. The nitrogen intake pipeline 111 is equipped with a nitrogen flow regulation circuit 10, and the hydrogen intake pipeline 112 is equipped with a hydrogen flow regulation circuit 20, which can regulate the flow of nitrogen and hydrogen respectively.

[0055] By setting a proportional control loop 30 between the nitrogen flow regulation loop 10 and the hydrogen flow regulation loop 20, the proportion of gas components in the feed gas can be adjusted, thereby providing a reference for subsequent regulation and control.

[0056] Nitrogen inlet line 111 and hydrogen inlet line 112 merge to form supplementary gas inlet line 113 of compressor compression section 11. Buffer outlet line 114 of compressor system buffer unit 14 is connected to supplementary gas inlet line 113, and buffer outlet bypass line 115 is provided on buffer outlet line 114. Supplementary gas pressure and flow control circuit 40 is provided between buffer outlet bypass line 115, buffer outlet line 114 and supplementary gas inlet line 113.

[0057] The compressor system buffer unit 14 is also connected to a buffer intake pipe 116, a buffer intake bypass pipe 117 is provided on the buffer intake pipe 116, and a buffer intake pressure and flow control circuit 50 is provided between the buffer intake bypass pipe 117 and the buffer intake pipe 116.

[0058] The installation of the compressor system buffer unit 14 and the intercooler 13, combined with the above-mentioned supplementary gas pressure and flow control circuit 40 and buffer intake gas pressure and flow control circuit 50, can form a flow buffer regulation and pressure control regulation mode, enabling the compressor and its auxiliary equipment to resist pressure fluctuation fatigue and flow pulse fatigue.

[0059] By setting up a supplementary gas pressure and flow control circuit 40 for pressure stabilization and a buffer inlet gas pressure and flow control circuit 50 in the compressor unit, as well as a compressor system buffer unit 14 and a hydrogen flow regulation circuit 20 for buffering, the operation is simplified, the response is fast, and the impact of hydrogen fluctuations on the compressor is mitigated, the operation of the compressor is stabilized, and it can be closely integrated with the operating conditions of wind and solar forecasting and electrolyzer hydrogen production.

[0060] A circulating gas inlet flow rate detection unit 80 is installed on the circulating gas inlet pipeline 212, and the circulating gas inlet flow rate detection unit 80 is electrically connected to the circulating gas pressure and flow control circuit 70. By combining the circulating gas inlet flow rate detection unit 80 with the circulating gas pressure and flow control circuit 70, the circulating gas inlet flow rate can be acquired in real time and fed back to the circulating gas pressure and flow control circuit 70, which facilitates the circulating gas pressure and flow control circuit 70 in controlling the opening degree of the flow control valve FV001 on the circulating gas bypass pipeline 213.

[0061] From the perspective of the composition of the temperature stabilization system, a first inlet gas pipeline 214, a second inlet gas pipeline 215, a third inlet gas pipeline 216 and a fourth inlet gas pipeline 217 are provided between the circulating gas inlet pipeline 212 and the ammonia synthesis tower 21. The third inlet gas pipeline 216 is located upstream of the external electric furnace 25 and does not heat the circulating gas. The top of the ammonia synthesis tower 21 is equipped with an internal electric furnace 26. The branch of the first inlet gas pipeline 214 that does not heat the external gas and the third inlet gas pipeline 216 are respectively connected to the internal electric furnace 26 to maintain normal gas intake.

[0062] The first inlet gas pipeline 214 includes an inlet gas pipeline 214a for heating the gas inside the tower and an inlet gas pipeline 214b for heating the gas outside the tower as a thermally stabilized gas pipeline. This configuration enables comprehensive control of the circulating gas entering the tower, meeting the gas intake requirements under different operating conditions.

[0063] Temperature regulation loops 100 are respectively installed between the heating gas inlet pipe 214a and the ammonia synthesis tower 21, between the second gas inlet pipe 215 and the ammonia synthesis tower 21, and between the third gas inlet pipe 216 and the ammonia synthesis tower 21. Specifically, each temperature regulation loop 100 is an inlet temperature regulation loop 100, which includes flow regulating valves installed on different gas inlet pipes and inlet gas temperature controllers 110 installed in different sections of the catalyst bed in the ammonia synthesis tower 21, ensuring the stability of the synthesis tower inlet temperature.

[0064] Based on the above-mentioned method of introducing the heat-stabilized gas from the external electric furnace 25 into the catalyst bed located at the top, and the connection point between the external heating gas pipeline 214b and the ammonia synthesis tower 21 is set in accordance with the location of the catalyst bed located at the top, the overall inlet gas temperature of the synthesis tower can be balanced and stabilized.

[0065] The inlet temperature regulation loops 100 on different inlet gas pipelines serve as components of the temperature stabilization system. Combined with the temperature and flow control loop 90, they form a synthesis tower temperature control system that regulates the inlet temperature, adjusts the external electric furnace 25, and controls the internal electric furnace 26, thus creating a dual-loop safety system. The external electric furnace 25 control system, constituted by the temperature and flow control loop 90, has no safety gas injection requirements and can remain in a hot standby state for extended periods.

[0066] The ammonia synthesis tower 21 is connected to the ammonia synthesis outlet pipeline 218. The ammonia synthesis outlet pipeline 218 is sequentially equipped with a steam generator 22, a boiler feed water heater 23, a heat exchanger 24, a water cooler 31, a cold exchanger 32, a primary ammonia cooler 33, a secondary ammonia cooler 34, an ammonia classifier 35, and an ammonia flash tank 36.

[0067] The ammonia synthesis tower 21, steam generator 22, boiler feedwater heater 23, and heat exchanger 24 constitute the ammonia synthesis and heat recovery unit. The water cooler 31, cold exchanger 32, primary ammonia cooler 33, secondary ammonia cooler 34, ammonia classifier 35, and ammonia flash tank 36 constitute the cooling separation unit. By introducing a portion of the circulating gas in the circulating gas bypass pipeline 213 into the cooling separation unit, and by adjusting the opening of the flow control valve FV001 in conjunction with the circulating gas pressure and flow control loop 70, the overall pressure and flow rate of the gas entering the tower can be stabilized.

[0068] In this application, the fourth inlet gas pipeline 217 serves as the start-up gas inlet pipeline. A temperature regulation loop 100 is provided between the synthetic ammonia outlet pipeline 218 and the fourth inlet gas pipeline 217. The temperature controller of the temperature regulation loop 100 is located upstream of the steam generator 22 and can control and adjust the opening of the flow regulating valve on the start-up gas inlet pipeline, thereby ensuring the stability of the overall system temperature under start-up conditions.

[0069] The ammonia synthesis tower 21 in this application is equipped with a suspended radial bed distributor for gas inlet and a gas temperature controller at the catalyst bed inlet to ensure the stability of the inlet temperature of the ammonia synthesis tower 21. A heat exchanger for temperature regulation is installed at the outlet of the ammonia synthesis tower 21 to recover the reaction heat of ammonia synthesis. It is jointly regulated with the steam generator 22 and the heat exchanger 24 to continuously change the proportion of recovered reaction heat according to the change of reaction load. That is, the lower the load of the device, the higher the proportion of recovered reaction heat, so as to maintain the thermal balance of the system under particularly low load.

[0070] Furthermore, the catalyst bed adopts highly active iron-based or other catalysts with strong resistance to fluctuations to adapt to rapid changes in flow rate, temperature, and pressure, so that the ammonia synthesis reaction system has the functions of temperature and flow regulation and rapid stabilization self-repair function to adapt to rapid load changes.

[0071] The pressure stabilization system in this application utilizes the dynamic balance of the actual required gas flow rate and the fixed catalyst quantity to ensure that the pressure rise and fall of PIC001 is gradual through continuous dynamic simulation, enabling stable and reliable operation within the 10-110% load range.

[0072] The PIC001 pressure control system calculates and controls the inlet hydrogen flow rate, the wind and solar predicted hydrogen production flow rate, the total circulating gas volume into the tower, and the system bypass gas volume, controlling pressure fluctuations to not exceed 20% and reducing pressure fatigue conditions.

[0073] By connecting the feed hydrogen flow rate and the circulating gas pressure and flow rate control loop 70 in series, the gas flow rate into the tower can be adjusted according to the feed hydrogen flow rate. The gas flow rate in the catalyst bed fluctuates with the feed hydrogen flow rate, so that it moves with the hydrogen and the operation flexibility can reach within the range of 5 to 125%. The system has a fast response and relatively stable pressure.

[0074] Adjusting the flow rate of the gas entering the tower ensures that the circulating gas volume changes little and is controllable. The entire ammonia synthesis system can act as a large "buffer container." The cooling separation and ammonia refrigeration system has sufficient response time to load changes. The cooling separation and ammonia refrigeration system is stable, simple, and reliable in operation.

[0075] The following description, in conjunction with the accompanying drawings and embodiments, further illustrates the wide-load follow-up flexible green ammonia synthesis system of the present invention.

[0076] Combination Figure 1 The compression unit includes a compressor compression section 11, a compressor circulation section 12, an intercooler 13, and a compressor system buffer tank. The system has the ability to adjust the hydrogen-nitrogen ratio flow rate. By setting up a supplementary gas pressure and flow control circuit 40 and a buffer intake gas pressure and flow control circuit 50, the system provides the adjustment functions of supplementary gas flow buffering and pressure control, enabling the compressor and its auxiliary equipment to resist pressure fluctuation fatigue and flow pulse fatigue.

[0077] Taking a 200kt / a green ammonia synthesis system as an example, at 100% load, the H2 flow rate into the system is 54888 Nm³. 3 / h corresponds to an N2 flow rate of 18296Nm. 3 / h. When the H2 flow rate decreases, the flow rate proportional regulation control loop 30 automatically reduces the amount of nitrogen entering the system and closes the nitrogen valve in the system. To maintain a stable inlet pressure at the compressor, the pressure stabilization system gradually opens the outlet valve of the compressor system buffer unit 14 according to the magnitude of the decrease in the system inlet flow rate, and the inlet valve of the compressor system buffer unit 14 also gradually opens. Following the flow of hydrogen, the green ammonia compressor control loop can maintain a stable compressor inlet pressure within a load range of 5% to 125%.

[0078] Combination Figure 2 For a 200kt / a green ammonia plant, at 100% load, the total circulating gas flow rate into the tower is FY3 = 243746 Nm³. 3 / h, the actual required gas volume entering the tower FY5 is calculated by subtracting the total circulating gas volume FY3 from the system's near-circuit gas volume FY4. At 100% load, FY4 = 0 Nm³. 3 / h, FY5=FY3.

[0079] When the load decreases rapidly and the system pressure drops quickly, the FY4 flow rate will gradually increase to maintain stable system pressure. When the load decreases to 20%, FY3 = 134060 Nm. 3 / h, FY4=48749Nm 3 / h, the actual required gas volume entering the tower is FY5=FY3-FY4=85311Nm 3 / h, the system pressure will not decrease by more than 15%.

[0080] Combination Figure 3 For a 200kt / a green ammonia plant, at 100% load, the thermally stable gas flow rate of the synthesis tower is approximately 1000 Nm³. 3 / h, to maintain the thermal standby status of pipelines and heating equipment, and when the load rapidly decreases to 20% load, the thermally stable gas volume is gradually increased to 10000 Nm³. 3 / h, the temperature of the catalyst bed 21a is in a stable state.

[0081] Meanwhile, at 100% load, the gas flow through the bottom heat exchanger 27 accounts for about 15% of the total gas flow into the tower; as the load decreases, the proportion of the gas flow through the bottom heat exchanger 27 to the total gas flow into the tower gradually increases. When the load decreases to 20%, the proportion of the gas flow through the bottom heat exchanger 27 to the total gas flow into the tower increases to 45% to maintain the thermal balance of the entire tower.

[0082] The wide-load follow-up flexible green ammonia synthesis system of the present invention has the advantages of fast response and safety and reliability, and the operation flexibility reaches 5 to 125%, which can be applied to the synthesis and production of green ammonia.

[0083] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0084] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A flexible green ammonia synthesis system with wide load responsiveness, characterized in that, include: Compression unit, ammonia synthesis and heat recovery unit, and cooling and separation unit; The compression unit includes a hydrogen inlet pipeline, and a hydrogen flow regulation circuit is provided on the hydrogen inlet pipeline. The ammonia synthesis and heat recovery unit includes an ammonia synthesis tower and an external electric furnace. The ammonia synthesis tower is connected to a circulating gas inlet pipeline. The circulating gas inlet pipeline includes a main circulating gas inlet pipeline, as well as a parallel branch circulating gas inlet tower pipeline and a circulating gas bypass pipeline. The circulating gas bypass pipeline is connected to the cooling and separation unit. A bypass flow regulation circuit is provided on the circulating gas bypass pipeline, and a circulating gas pressure and flow control circuit is provided on the circulating gas inlet main pipeline. The hydrogen flow regulation circuit and the bypass flow regulation circuit are electrically connected to the circulating gas pressure and flow control circuit. The circulating gas pressure and flow control circuit can receive wind and solar forecasts converted into hydrogen flow and control the actual required gas flow into the tower according to the different hydrogen flow and circulating gas flow received. The external electric furnace is connected to a thermally stabilized gas pipeline, and a temperature and flow control loop is provided between the thermally stabilized gas pipeline and the ammonia synthesis tower. The temperature and flow control loop can control the flow rate of the circulating gas in the thermally stabilized gas pipeline according to the received hydrogen flow rate. The ammonia synthesis tower is equipped with multiple catalyst beds, which adopt a suspended radial gas distribution inlet. Cooling devices are installed between different catalyst beds, and a bottom heat exchanger is installed at the bottom of the bottom catalyst bed.

2. The wide-load follow-up flexible green ammonia synthesis system according to claim 1, characterized in that, The compression unit includes a compressor compression section, a compressor circulation section, an intercooler, and a compressor system buffer unit, wherein the compressor system buffer unit includes a buffer tank or a buffer tube. The compressor's compression section includes a nitrogen inlet pipe and a hydrogen inlet pipe. A nitrogen flow rate regulating circuit is provided on the nitrogen inlet pipe, and a proportional regulation control circuit is provided between the nitrogen flow rate regulating circuit and the hydrogen flow rate regulating circuit.

3. The wide-load follow-up flexible green ammonia synthesis system according to claim 2, characterized in that, The nitrogen inlet pipeline and the hydrogen inlet pipeline merge to form the supplementary gas inlet pipeline of the compressor compression section. The buffer outlet pipeline of the compressor system buffer unit is connected to the supplementary gas inlet pipeline, and a buffer outlet bypass pipeline is provided on the buffer outlet pipeline. A supplementary gas pressure and flow control circuit is provided between the buffer outlet bypass pipeline, the buffer outlet pipeline and the supplementary gas inlet pipeline.

4. The wide-load follow-up flexible green ammonia synthesis system according to claim 2, characterized in that, The compressor system buffer unit is also connected to a buffer intake pipe, and a buffer intake bypass pipe is provided on the buffer intake pipe. A buffer intake pressure and flow control circuit is provided between the buffer intake bypass pipe and the buffer intake pipe.

5. The wide-load follow-up flexible green ammonia synthesis system according to claim 1, characterized in that, A circulating gas inlet flow detection unit is installed on the circulating gas inlet pipeline, and the circulating gas inlet flow detection unit is electrically connected to the circulating gas pressure and flow control circuit.

6. The wide-load follow-up flexible green ammonia synthesis system according to claim 1, characterized in that, A first inlet gas pipeline, a second inlet gas pipeline, a third inlet gas pipeline, and a fourth inlet gas pipeline are provided between the circulating gas inlet pipeline and the ammonia synthesis tower. The third gas inlet pipeline is located upstream of the external electric furnace, and an internal electric furnace is installed at the top of the ammonia synthesis tower. The first gas inlet pipeline and the third gas inlet pipeline are respectively connected to the internal electric furnace. The first inlet gas pipeline includes an inlet gas pipeline for heating inside the tower and an inlet gas pipeline for heating outside the tower, which serves as the thermally stabilized gas pipeline.

7. The wide-load follow-up flexible green ammonia synthesis system according to claim 6, characterized in that, Temperature regulation loops are respectively provided between the heating gas inlet pipe and the ammonia synthesis tower, between the second gas inlet pipe and the ammonia synthesis tower, and between the third gas inlet pipe and the ammonia synthesis tower.

8. The wide-load follow-up flexible green ammonia synthesis system according to claim 6, characterized in that, The ammonia synthesis tower is connected to a synthetic ammonia outlet pipeline, and the fourth inlet gas pipeline serves as the start-up gas inlet pipeline. A temperature regulation loop is provided between the synthetic ammonia outlet pipeline and the fourth inlet gas pipeline.

9. The wide-load follow-up flexible green ammonia synthesis system according to claim 8, characterized in that, The temperature control loop includes an inlet gas temperature controller, which is configured to correspond to different sections of the catalyst bed.

10. The wide-load follow-up flexible green ammonia synthesis system according to claim 8, characterized in that, The connection point between the external heating gas pipeline and the ammonia synthesis tower is set at a location corresponding to the location of the catalyst bed in the top section.

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