Green ammonia synthesis heat recovery intelligent flexible control system and method thereof

Abstract

The invention discloses a green ammonia synthesis heat recovery intelligent flexible control system and a method thereof.The green ammonia synthesis heat recovery unit is provided with a first bypass pipeline in parallel, the upstream of the two parallel branches is provided with a shunt control part, and the shunt control part adjusts the opening degree to control high-temperature synthesis gas to enter the first bypass pipeline; the heat of the high-temperature synthesis gas is intelligently and flexibly distributed and utilized; the feeding flow, feeding temperature and intelligent flexible control part, the intelligent flexible control system and the shunting control part form a control loop; according to the collected production load information, an instruction signal is formed through processing and analysis, decision making and control of the intelligent flexible control system, the opening degree of the flow dividing control part is interactively adjusted in real time, and the flow of the first bypass pipeline is changed, so that the flow is matched with the feeding gas flow and the heat exchange capacity of the efficient heat exchanger; and the temperature in the green ammonia synthesis tower is kept stable under various loads. The method is suitable for synthesizing green ammonia by taking green hydrogen as a raw material, and intelligent flexible self-heating process control that loads move along with a source is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of green ammonia synthesis production, and in particular to an intelligent flexible control system and method for green ammonia synthesis heat recovery. Background Art

[0002] As an extremely important basic chemical raw material, ammonia is widely used in many fields such as modern agriculture and chemical industry. It is currently developing vigorously in the direction of "zero-carbon fuel" and is very likely to become an extremely important fuel in the future carbon reduction fuel. However, its production process is a typical high-energy-consuming process, which consumes a lot of energy resources, mainly due to the high temperature, high pressure and material handling required for the ammonia synthesis reaction. In the traditional synthetic ammonia production process, although a large amount of heat is generated, for example, the high-temperature synthesis gas coming out of the ammonia synthesis tower carries considerable heat, but the recovery and utilization efficiency of this heat under green electricity conditions is often unsatisfactory. At present, although some traditional processes recover the synthesis heat to preheat the feed gas, these traditional processes are almost stably operated under a stable feed rate. The process cannot be adjusted randomly and flexibly, and it is difficult to make timely and effective adjustments according to the frequently changing conditions (such as production load fluctuations, raw gas composition and flow changes, etc.) in the production process of green electricity to green hydrogen and green hydrogen to green ammonia. If additional energy is required to heat the feed gas, this not only increases the production cost, but also does not meet the current green, low-carbon and sustainable industrial requirements.

[0003] Most of the existing synthetic ammonia feed gas preheating processes adopt relatively fixed processes and control methods, and the use of heat is not accurate and flexible enough. For example, in the prior art: the application number CN201520661480.6 discloses an ammonia synthesis tower waste heat recovery and utilization system, in which the synthesis gas outlet of the ammonia synthesis tower is connected to the synthesis gas inlet of the synthetic medium-pressure boiler, the synthesis gas outlet of the synthetic medium-pressure boiler is connected to the synthesis gas inlet of the synthetic secondary medium-pressure boiler, and then connected to the heat source inlet of the feed water preheater, and the hot water preheated by the feed water preheater passes through the boiler water outlet to the synthetic medium-pressure boiler and the synthetic secondary medium-pressure boiler, and the heat source outlet of the feed water preheater is connected to the heat source inlet of the inlet and outlet tower heat exchanger. This technology adopts a relatively fixed process and control method; on the one hand, this type of process design does not fully consider the dynamic changes of heat supply and demand under variable working conditions, and cannot adjust the preheating temperature and heat distribution in real time according to actual conditions. In the case of changes in production feed load, it is easy to cause insufficient or excessive preheating of the feed gas, affecting the efficiency and stability of the subsequent synthetic ammonia reaction. On the other hand, the corresponding control method is also relatively simple and lagging, and part of the heat is not fully utilized, resulting in energy waste and increased production costs. It is also contrary to the current green, low-carbon, energy-saving and emission-reduction industrial development concept. In addition, under variable load conditions, traditional processes often impose harsh operating conditions on the synthesis tower, such as frequent and substantial adjustments to the temperature, pressure and material flow of the synthesis tower, which not only increases the operating risks of the synthesis tower equipment, such as thermal stress fatigue, and local reaction abnormalities caused by uneven material distribution, but also reduces the service life, safety and reliability of the equipment.

[0004] Due to the volatility of new energy sources such as wind power and photovoltaics, such as the volatility of wind turbine output power and wind speed, the photovoltaic power generation system is affected by natural factors such as meteorological conditions, which will lead to fluctuations in power generation. The production and preparation of green hydrogen using new energy sources such as wind power and photovoltaics will also fluctuate, and there is a problem of "load following source movement"; in order to match the synthesis of green ammonia with the production and preparation of green hydrogen, and realize "load following source movement", patent application number CN202410021111.4 discloses a new energy hydrogen production dynamic synthesis of green ammonia system and its operation method. The system is equipped with multiple ammonia synthesis regulating towers, multiple heat exchangers and multiple regulating valves; each device is connected according to the system operation process. Although it realizes the variable load regulation of the green ammonia synthesis system, its structure is complex, and different sizes of green ammonia synthesis towers are set to correspond to different production loads. Not only does the equipment construction cost increase greatly, but also the pipeline supporting valves are complex, and the operation is difficult, requiring high proficiency and adaptability of operators, the operation error rate is high, and the automatic control performance is poor.

[0005] Therefore, there is an urgent need for a method that can not only respond to various operating conditions changes in the ammonia synthesis process in a timely and flexible manner, but also can deeply process and analyze, make decisions and control the process to achieve continuous optimization of the green ammonia synthesis process, so as to meet the scenarios of green electricity to green hydrogen and green hydrogen to green ammonia, while improving the energy utilization level and overall economic benefits of green ammonia production.

[0006] In view of the above, the present invention proposes a method of directly preheating the feed gas by using the synthesis gas without heat recovery from the green ammonia synthesis tower, combined with an intelligent flexible control process method to solve the above problems. Summary of the invention

[0007] The object of the present invention is to overcome the defects in the prior art and provide an intelligent flexible control system and method for heat recovery of green ammonia synthesis.

[0008] To achieve the above-mentioned object, the technical solution of the present invention is as follows: an intelligent flexible control system for green ammonia synthesis heat recovery, comprising a bypass regulation system: a first bypass pipeline is arranged in parallel with a green ammonia synthesis heat recovery unit so that the two form a parallel branch, and a shunt control unit is arranged upstream of the two parallel branches, and the shunt control unit controls the flow of the two parallel branches independently or collaboratively controls the flow of the two parallel branches; When the production load changes, the flow splitting control unit adjusts the opening to control part or all of the high-temperature synthesis gas to enter the first bypass pipeline, and intelligently and flexibly distributes and utilizes the heat of the high-temperature synthesis gas; High-efficiency heat exchange system: Use high-efficiency heat exchangers to exchange heat between high-temperature synthesis gas and feed gas; Intelligent flexible control unit: It collects feed flow, feed temperature and system pressure data in real time. As the control end, the intelligent flexible control unit forms a control loop with the diversion control unit. The intelligent flexible control unit adjusts the diversion control unit in real time according to the control signal calculated based on the collected production load information, changes the diversion volume of the first bypass pipeline to match it with the feed gas flow and the heat exchange capacity of the high-efficiency heat exchanger, and keeps the temperature inside the green ammonia synthesis tower stable under various loads.

[0009] Furthermore, the flow control unit is a three-way regulating valve, which changes its opening according to the received control signal to adjust and distribute the flow of the two parallel branches. An independent three-way regulating valve can achieve coordinated regulation of the flow of the two branch roads, with a simple structure and cost saving.

[0010] Furthermore, the flow splitting control unit is to respectively set control valves on the two parallel branches, and the control valves on the two parallel branches respectively and independently adjust the flow of the corresponding branches. The two independently set control valves are used to achieve independent, high-precision and accurate control of each branch.

[0011] Furthermore, the high-efficiency heat exchanger is any one of a wound tube heat exchanger, a shell and tube heat exchanger, a spiral plate heat exchanger, and a plate-fin heat exchanger; in actual use, the type of use of the heat exchanger is not restricted and other high-efficiency heat exchangers can also be used to replace the setting.

[0012] Furthermore, the high-efficiency heat exchanger, heat recovery unit and green ammonia synthesis tower form a device, which is a heat pipe reactor or an autothermal reactor. The high-efficiency heat exchanger, heat recovery unit and green ammonia synthesis tower form a green ammonia synthesis heat recovery intelligent flexible control system, in which the green ammonia synthesis reactor is a heat pipe reactor or an autothermal reactor, or other reactor structure types.

[0013] Furthermore, the intelligent flexible control unit at least includes a perception layer, a data processing and analysis layer, and a decision-making and control layer; the perception layer includes data acquisition sensors installed at different key positions of the heat recovery flexible control system of the green ammonia synthesis system, including temperature sensors, flow sensors, and pressure sensors; the perception layer collects key parameters in the process in real time, continuously, and accurately, and the key parameters include but are not limited to: the temperature, flow, and pressure of the feed gas, the inlet and outlet temperature, flow, and pressure of the green ammonia synthesis tower, and the temperature distribution data of different parts in the green ammonia synthesis tower.

[0014] Furthermore, the data processing and analysis layer at least includes heat calculation of the system, and the heat calculation method includes the following steps: modeling the system based on the first law of thermodynamics (i.e., the law of conservation of energy), the van't Hoff equation, the Arrhenius formula, etc., and calculating the heat required for the synthesis tower inlet gas to enter the synthesis tower shell and enter the catalyst frame, that is, the heat required for the inlet gas to heat up to the activation temperature. The calculation formula is as follows: ①.

[0015] Furthermore, the heat required for the synthesis tower outlet gas to be heated to the temperature of the synthesis tower shell is calculated using the following formula: ) ② Calculate the heat loss of the synthesis tower to the surrounding environment, the calculation formula is: ③.

[0016] Furthermore, the energy balance equation of the green ammonia synthesis tower is calculated as follows: ④.

[0017] Furthermore, the energy balance equation of the high-efficiency heat exchanger is calculated as follows: )⑤.

[0018] Furthermore, the simultaneous equations ①~④ give the required inlet gas temperature entering the synthesis tower under different loads: , and then the product of the flow rate of the first bypass pipeline and the temperature difference of the outlet gas entering and leaving the heat exchanger is obtained through the energy balance equation ⑤: ); The temperature difference between the two ends of the heat exchanger is not less than 5°C, and the conditional equation is obtained: ⑥ According to conditional equation ⑥, we get The minimum value to meet the stable operation of the synthesis tower, the temperature of the discharge gas entering the heat exchanger It can be adjusted by the bypass regulating valve; at this time, the temperature adjustment needs to meet the conditional equation: ⑦ If this is not met, it will not be possible to compensate for the heat loss of the synthesis tower by increasing the heat transfer of the high-efficiency heat exchanger. That is the adjustment ratio of the first bypass pipeline, and the opening of the three-way regulating valve is controlled according to the adjustment ratio.

[0019] In order to accurately calculate the heat of the synthesis tower, it is necessary to calculate the temperature and component content at different positions in the tower. First, a micro-segment is selected in the reactor for reaction kinetics calculation; We choose the Temkin-Pyzhev adsorption model to describe the relationship between the ammonia synthesis reaction rate and factors such as temperature, pressure, and gas composition: ⑧ in, is the reaction rate, , is the forward and reverse reaction rate constant, determined by the Arrhenius formula, the forward reaction rate constant , the reverse reaction rate constant ; , is a constant related to the adsorption equilibrium constant and is related to the reaction mechanism; , , are the partial pressures of nitrogen, hydrogen and ammonia, respectively, , is the activation energy of the forward and reverse reactions, R is the universal gas constant, T is the gas temperature of the micro-segment, and t is the time.

[0020] Then make heat balance for this micro segment: ⑨ in, is the micro-segment volume, is the average specific heat capacity of the micro-segmented gas.

[0021] At the same time, the micro-segment has the following relationship: ⑩ in, is the average gas density of this micro-segment.

[0022] The temperature T and component content at different positions in the synthesis tower are obtained by combining equations ⑧, ⑨, and ⑩. , , , and substituting it into equations ① and ②, we can accurately calculate the enthalpy change of the reaction process.

[0023] A process control method for a green ammonia synthesis heat recovery intelligent flexible control system, wherein the intelligent flexible control unit inputs parameters of the intelligent flexible control unit according to the change in feed load, the temperature and pressure data of key nodes of the system, and the intelligent flexible control unit processes and analyzes, calculates and models, makes decisions and controls the output of control parameters of the shunt control unit that match the actual production load, and the shunt control unit adjusts the flow of the first bypass pipeline to shunt out a high-temperature synthesis gas flow that matches the feed gas flow and the heat exchange capacity of the high-efficiency heat exchanger, so as to keep the temperature in the green ammonia synthesis tower stable under various loads. That is, to achieve that the temperature at each location in the green ammonia synthesis tower under various loads is basically unchanged compared with the temperature at the location corresponding to any load, thereby maintaining the efficient and stable ammonia synthesis reaction in the green ammonia synthesis tower under various loads.

[0024] The advantages and beneficial effects of the present invention are: 1. Enhance process adaptability: Whether it is frequent changes in production load, changes in raw gas characteristics or other complex working conditions, this intelligent flexible control system and method can effectively respond. The intelligent flexible control system is equipped with advanced methods such as big data analysis, machine learning algorithms, fuzzy logic control, expert intelligent control, neural network adaptive control and optimization algorithms. It can evaluate the performance of the process under different working conditions in real time, and flexibly and efficiently use the heat generated by the synthetic ammonia reaction to preheat the feed gas, increase the feed temperature to compensate for the heat lost to the surrounding environment through the outer surface of the ammonia synthesis tower during the production process, so as to achieve the "constant temperature" or "near constant temperature" operation of the ammonia synthesis tower, and realize the net ammonia value of synthetic ammonia under "variable load" conditions. The operation is unchanged, reducing the harsh operating conditions for the synthesis tower equipment under "variable load" conditions, and improving the safety and stability of the operation. Further optimization provides a basis for intelligent control to ensure that the feed gas preheating temperature is always stable within the range that meets the optimal reaction conditions for synthetic ammonia, thereby ensuring the efficient conduct of the green ammonia synthesis reaction and improving the adaptability and operational stability of the entire process to different working conditions;

[0025] 2. Improve energy efficiency: Through this intelligent flexible control system and method, heat resources can be flexibly allocated according to the actual working conditions of green ammonia production, and the feed gas can be accurately preheated, which minimizes the need for additional energy to heat the feed gas, significantly improves the energy efficiency of the entire green ammonia production system, reduces production costs, and meets the industry requirements of energy conservation, emission reduction and sustainable development; 3. Improve equipment safety and life: In the traditional ammonia synthesis process, variable load conditions often expose the ammonia synthesis tower to harsh operating conditions (such as large and frequent fluctuations in temperature, pressure and material flow) and serious equipment fatigue problems, which challenges safety performance and shortens life. However, this intelligent flexible control system and method have obvious advantages. Through precise regulation of each link, it effectively reduces the alternating load of the equipment. When the load is variable, it can quickly and intelligently adjust the key parameters such as the flow rate and temperature of the synthesis gas and feed gas according to the real-time situation to prevent the drastic fluctuations of the key parameters of the synthesis tower, greatly reduce the harsh operating requirements for the synthesis tower equipment, and significantly reduce the fatigue of the equipment, thereby greatly improving the safety performance of the equipment, extending the service life of the equipment, reducing the frequency and cost of equipment maintenance, and enhancing the stability and reliability of the entire synthetic ammonia production system under different working conditions, providing strong support for the efficient and sustainable development of the synthetic ammonia industry.

[0026] 4. Optimize the process for continuous improvement: This intelligent flexible control system method can analyze the process comprehensively, deeply and in real time, and provide detailed information from multiple dimensions such as energy balance, heat transfer process, and operating adaptability, providing a scientific basis for continuous process optimization. By continuously adjusting the control strategy and improving the equipment maintenance plan, the process performance is continuously improved, and the efficient operation state is maintained for a long time, bringing continuous energy-saving and consumption-reducing advantages to green ammonia production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a process flow chart of an intelligent flexible control system for heat recovery from green ammonia synthesis according to the present invention; Figure 2 It is an energy balance analysis diagram of the green ammonia synthesis heat recovery intelligent flexible control system in the present invention; Figure 3 It is a process control diagram of the intelligent flexible control system for heat recovery of green ammonia synthesis in the present invention; In the figure: 100, feed gas; 101, synthesis tower inlet gas; 102, high-temperature synthesis gas; 103, first bypass pipeline; 104, heat utilization pipeline; 200, flow sensor; 201, temperature control sensor; 202, three-way regulating valve; 203, control valve; 204, diversion control unit; 300, high-efficiency heat exchanger; 301, green ammonia synthesis tower; 302, heat recovery unit; 303, feed preheater; 400, synthesis tower shell; 401, catalyst frame; 601, temperature control regulating valve; 602, temperature transmission sensor; 603, first temperature sensor; 604, second temperature sensor; 605, third temperature sensor; 606, fourth temperature sensor. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0029] An intelligent flexible control system for heat recovery from green ammonia synthesis, such as Figure 1-2 As shown, it includes a green ammonia synthesis tower 301, a feed pipeline entering the green ammonia synthesis tower 301, and a discharge pipeline leaving the green ammonia synthesis tower 301. The discharge pipeline is divided into two parallel branches, which are a heat utilization pipeline 104 and a first bypass pipeline 103. The heat utilization pipeline 104 is provided with a heat recovery unit 302.

[0030] The two parallel branch roads are controlled by a flow control unit at the upstream end to control the flow of the two branch roads; the flow control unit is a three-way regulating valve 202. The high-temperature synthesis gas 102 diverted by the first bypass pipeline 103 is used as a heat source to perform secondary heat exchange on the feed gas 100; the downstream end of the first bypass pipeline 103 merges with the heat utilization pipeline 104 to perform primary heat exchange on the feed gas 100;

[0031] In actual use, the feed gas 100 is gradually heated up through the primary heat exchange and the secondary heat exchange in sequence, and then reaches the temperature of the green ammonia synthesis tower inlet gas 101, satisfying the reaction conditions of the materials in the green ammonia synthesis tower 301; it can be understood that the primary heat exchange is to preheat the feed gas 100 with heat after the high-temperature synthesis gas passes through the heat recovery unit 302. When the load decreases, the flow rate of the high-temperature synthesis gas 102 also decreases accordingly. If the heat of the high-temperature synthesis gas 102 is still used for the heat recovery unit, it is difficult to preheat the feed gas 100 to a certain temperature to maintain the temperature of the green ammonia synthesis tower 301; the first bypass pipeline 103 set in this process diverts the high-temperature synthesis gas at low load, so that it does not pass through the heat recovery unit, but passes through the high-efficiency heat exchanger to perform secondary heat exchange on the feed gas 100, so that the feed gas temperature is further increased and is sufficient to maintain the temperature in the green ammonia synthesis tower stable; thereby realizing that the system can always maintain the stability of the internal temperature of the green ammonia synthesis tower when facing different loads, thereby ensuring the reaction efficiency.

[0032] Specifically, the primary heat exchange is a feed preheater 303 provided on the feed pipeline, the feed gas 100 is used as a cold source of the feed preheater 303, and the first bypass pipeline 103 and the heat utilization pipeline 104 are merged as the heat source of the feed preheater 303. The secondary heat exchange is a high-efficiency heat exchanger 300 provided at the rear end of the feed preheater 303, the feed gas 100 is used as a cold source of the feed preheater 303, and the high-temperature synthesis gas 102 of the first bypass pipeline 103 is a heat source. As an embodiment, Figure 1 , 3 As shown, the high-efficiency heat exchanger 300 and the heat recovery unit 302 are independently arranged outside the green ammonia synthesis tower 301. In actual use, the type of the heat exchanger is not limited and other high-efficiency heat exchangers can also be used to replace the arrangement.

[0033] As another embodiment, the high-efficiency heat exchanger 300, the heat recovery unit 302 and the green ammonia synthesis tower 301 are integrated into one device (not shown in the figure). Specifically, a heat pipe reactor or an autothermal reactor or a reactor of other structural types can be used. In actual use, the type of use of the reactor is not limited and other structural types of reactors can also be used to replace the setting.

[0034] Furthermore, the feed pipeline is provided with a second bypass pipeline, which is arranged in parallel with the feed preheater 303 and the high-efficiency heat exchanger 300 as a bypass, and the second bypass pipeline is provided with a temperature control valve 601. A temperature control sensor 201 for measuring the temperature of the synthesis tower inlet gas 101 is provided at the top entrance of the green ammonia synthesis tower 301, and the temperature control sensor 201 is electrically connected with the temperature control valve to form a control loop for controlling the valve opening by temperature parameters. As a control method, when the temperature control sensor 201 detects that the temperature of the synthesis tower inlet gas 101 is higher than the calculated temperature range of the corresponding production load, the temperature control valve 601 is opened to a certain degree through the control loop, so that the low-temperature feed gas 100 is mixed with the feed gas 100 after the secondary heat exchange to cool down, so as to achieve control when the temperature is high, and then when the production load is changed, the temperature of the synthesis tower inlet gas 101 is kept consistent with the temperature required for the corresponding load calculation, so as to maintain the temperature in the green ammonia synthesis tower stable.

[0035] Furthermore, a flow sensor 200 is provided on the feed pipeline, and the flow sensor 200, the temperature control sensor 201 and the three-way regulating valve 202 are electrically connected, forming a control loop that uses the total inlet flow as the first parameter and the temperature of the synthesis tower inlet gas 101 as the second parameter to control the opening of the three-way regulating valve 202. When the system load is reduced, the opening of the three-way regulating valve 202 is controlled by the feedback parameters of the flow sensor 200 and the temperature control sensor 201 combined with the calculation data of the intelligent flexible control unit, so that the flow of the corresponding high-temperature synthesis gas 102 enters the first bypass pipeline 103, so that the high-temperature synthesis gas that does not pass through the heat recovery unit 302 is directly used to heat the feed gas 100, thereby relatively increasing the temperature of the synthesis tower inlet gas 101, thereby maintaining the temperature in the green ammonia synthesis tower stable at low load.

[0036] Furthermore, the discharge pipe is provided with a temperature transmission sensor 602 for measuring the temperature of the high-temperature synthesis gas 102; a first temperature sensor 603 is provided between the feed preheater 303 and the high-efficiency heat exchanger 300; a second temperature sensor 604 is provided on the green ammonia synthesis tower 301 for measuring the temperature of the catalyst frame 401; a third temperature sensor 605 is provided on the first bypass pipe 103 downstream of the high-efficiency heat exchanger 300; a fourth temperature sensor 606 is provided on the confluence pipe between the first bypass pipe 103 and the heat utilization pipe 104. Each temperature sensor is used to monitor the operating status of the system.

[0037] The specific control steps are: The present invention mainly consists of three parts: bypass regulation, efficient heat exchange, and intelligent flexible control unit, and achieves efficient and flexible use of heat through mutual cooperation: A first bypass pipeline 103 and a corresponding regulating valve are provided in the heat recovery unit 302. When encountering special working conditions (such as production load fluctuations, changes in raw gas composition and flow rate, heat exchanger failure, etc.), the heat recovery unit 302 can be partially or completely bypassed by adjusting the bypass valve opening, thereby achieving rapid emergency control of the temperature of the synthesis tower inlet gas 101 and ensuring the safety and stability of the entire system.

[0038] At the same time, a high-efficiency heat exchanger 300 is used to realize the transfer of heat from the high-temperature synthesis gas 102 to the feed gas 100. The type of heat exchanger can be selected according to the actual process requirements and working conditions, such as shell and tube heat exchanger, spiral plate heat exchanger or plate fin heat exchanger. The high-efficiency heat exchanger 300 and the heat recovery unit 302 can be independent of the green ammonia synthesis tower 301, or the three can form a device, such as a heat pipe reactor, an autothermal reactor, etc. The designed heat exchange area of ​​the heat exchanger is determined based on the energy balance calculation of the overall process, and the heat exchange requirements under different production loads must be fully considered to ensure that the requirements for preheating the feed gas 100 can be met under various working conditions.

[0039] The feed gas 100 (including hydrogen and nitrogen raw gas) is supplied by their respective gas sources. Before entering the feed preheater 303, its initial temperature is relatively low, and its flow rate will change with factors such as production load and process adjustment. In order to ensure that the feed gas 100 can be stably and efficiently preheated in the feed preheater 303 and the high-efficiency heat exchanger 300, a flow sensor 200 is provided on the feed gas 100 pipeline, and a temperature control sensor 201 is provided on the synthesis tower inlet gas 101 pipeline. When the load is low, the three-way regulating valve 202 is enabled. The regulating valve adjusts the flow rate of the first bypass pipeline 103 in real time according to the production load and the information fed back from the intelligent flexible control unit, so that it matches the flow rate of the feed gas 100 and the heat exchange capacity of the high-efficiency heat exchanger 300. For example, if the flow rate of the feed gas 100 is lower than the rated flow rate, the controller will increase the opening of the three-way regulating valve 202 to allow more high-temperature synthesis gas 102 to enter the high-efficiency heat exchanger 300, increase the heat transfer, and thus increase the preheating temperature of the feed gas 100, thereby increasing the temperature of the synthesis tower inlet gas 101; in the process of increasing the temperature of the synthesis tower inlet gas, if the temperature is higher than the target temperature, the opening of the synthesis gas flow regulating valve is appropriately reduced.

[0040] The aforementioned adjustment method may also be used for auxiliary adjustment, that is, when the inlet gas temperature of the synthesis tower exceeds the calculated temperature quickly and still has an upward trend, the temperature control valve 601 may be opened to quickly cool down the inlet gas temperature of the synthesis tower. It can be understood that the adjustment priority of the three-way control valve 202 is higher than that of the temperature control valve 601.

[0041] An intelligent flexible control unit based on advanced methods such as big data analysis, machine learning algorithms, fuzzy logic control, expert intelligent control, neural network adaptive control and optimization algorithms realizes intelligent flexible control of the entire green ammonia synthesis heat recovery system. The intelligent flexible control unit is composed of at least a perception layer composed of multiple sensors (temperature sensors, flow sensors 200), a processing and analysis layer composed of a controller (such as a programmable logic controller PLC or a distributed control system DCS, etc.), and a decision-making and control layer composed of an actuator (regulating valve).

[0042] In addition, during the preheating process of the feed gas 100, in order to prevent the temperature of the green ammonia synthesis tower inlet gas 101 from being too high due to a failure of the intelligent flexible control unit or other abnormal conditions, an over-temperature protection device is provided at the outlet of the high-efficiency heat exchanger 300. When the temperature of the synthesis tower inlet gas 101 exceeds the preset safety over-temperature threshold, the over-temperature protection device automatically starts, turns on the emergency cooling system, and injects low-temperature feed gas 100 into the synthesis tower inlet gas 101 pipeline to quickly reduce the temperature of the synthesis tower inlet gas 101, thereby avoiding damage to the subsequent green ammonia synthesis reaction catalyst and equipment due to high temperature.

[0043] As another implementation: The flow splitting control unit 204 is a control valve 203 respectively arranged on two parallel branches, and the control valves 203 on the two parallel branches respectively independently adjust the flow of the corresponding branches. Two independently arranged control valves 203 are used to achieve independent, high-precision and accurate control of each branch. In the above-mentioned embodiment, the flow splitting control unit 204 adopts the form of a three-way regulating valve 202. In actual use, the flow splitting control unit 204 can also be divided into multiple control valves 203. Specifically, as shown in FIG. Figure 3 As shown, the high temperature synthesis gas 102 is branched into two parallel branches, and the two branches are respectively provided with automatically controllable control valves 203. The two valves are independently controlled to more accurately divert the high temperature synthesis gas 102.

[0044] As an embodiment of the intelligent flexible control unit, specifically, it is composed of at least three layers: a perception layer, a data processing and analysis layer, and a decision-making and control layer.

[0045] Among them, the perception layer is composed of inlet and outlet flow sensors, inlet and outlet temperature sensors, and inlet and outlet pressure sensors. It is the basis of the entire intelligent flexible control unit. Through sensors, various production, transmission and consumption states in the system are monitored in real time. For example, the inlet and outlet flow sensors can obtain the changes in inlet and outlet flow in real time, and the temperature sensors can obtain the temperature changes in the real-time system. The data collected by the sensors include parameters such as flow, pressure, and temperature, which provide a basis for subsequent analysis and control.

[0046] The collected data is collected and processed in the data processing and analysis layer. First, the data must be cleaned to remove outliers and erroneous data. Then, based on the first law of thermodynamics (i.e., the law of conservation of energy), the van't Hoff equation, the Arrhenius formula and other applicable physical and chemical laws and formulas, the model is established, and then data analysis techniques such as big data analysis and machine learning algorithms are used to mine the laws and potential information in the data, fit various applicable physical and chemical laws and formulas, so that the values ​​of physical constants are more accurate and effective, and the model can better predict, real-time and effectively control the green ammonia synthesis. For example, by analyzing the historical data and real-time data of the inlet and outlet temperature and the inlet and outlet flow, the changing trend of the inlet and outlet temperature and the inlet and outlet flow can be predicted, providing a reference for the reasonable scheduling of the control of the first bypass flow distribution; analyzing the energy balance in the intelligent flexible control unit of the green ammonia synthesis heat recovery and the temperature distribution data in the green ammonia synthesis tower can optimize the temperature setting of the feed gas after preheating to optimize the temperature distribution in the green ammonia synthesis tower, and improve the net ammonia value and catalyst life.

[0047] According to the results obtained by the data processing and analysis layer, the decision and control layer makes intelligent decisions and implements control. This layer is based on advanced methods such as fuzzy logic control, expert intelligent control, neural network adaptive control and optimization algorithm, and the shunt controller completes the execution of decision and control. For the intelligent flexible control unit for heat recovery of green ammonia synthesis, the decision involves the coordinated scheduling of feed flow changes and the shunt control unit. For example, when the feed amount decreases, it can be decided to increase the proportion of the flow from the shunt control part to the first bypass flow, and at the same time adjust the system's operating mode to reduce the amount of high-pressure steam generated, and instead use high-temperature synthesis gas to preheat the feed gas, increase the feed gas temperature, and make up for the heat dissipation loss of the green ammonia synthesis tower, so that the temperature in the green ammonia synthesis tower does not change with the feed amount and is always in a stable state.

[0048] Calculation method of intelligent flexible control unit: The calculation method matched with the above-mentioned flexible process aims to analyze the process comprehensively, deeply and in real time, and provide data support and decision-making basis for the stable operation of the intelligent flexible control unit, which mainly includes the following contents: Through various sensors (temperature sensors, flow sensors 200, etc.) installed at different key positions, key parameter data in the process are collected in real time, continuously and accurately. These data include but are not limited to: the temperature, flow rate and pressure of the feed gas 100, the inlet and outlet temperature, flow rate and pressure of the green ammonia synthesis tower 301, and the temperature distribution of different parts in the green ammonia synthesis tower 301. The data collected by the sensor has a high frequency to ensure that subtle changes in the process can be captured, providing rich and accurate raw data for subsequent analysis.

[0049] Based on the collected real-time data, the energy balance algorithm is built into the intelligent flexible control unit to perform energy balance analysis and control the three-way regulating valve 202 in real time. The specific calculation method is as follows:

[0050] First, calculate the heat required for the inlet gas of the synthesis tower to enter the synthesis tower shell and enter the catalyst frame, that is, the heat required for the inlet gas to heat up to the activation temperature. According to the formula ) ①, Where: The heat required to heat the inlet gas of the synthesis tower to the activation temperature. is the enthalpy of the inlet gas entering the catalyst frame, is the enthalpy of the inlet gas entering the shell of the synthesis tower, is the mass flow rate of the inlet gas, is the specific heat capacity of the inlet gas entering the catalyst frame (calculated by referring to the relevant thermodynamic data table or empirical formula based on the composition and temperature of the syngas), is the specific heat capacity of the inlet gas entering the shell of the synthesis tower, is the temperature of the inlet gas entering the shell of the synthesis tower, It is the temperature of the inlet gas entering the catalyst frame.

[0051] Then, the heat required for the gas at the outlet of the catalyst frame to rise to the temperature of the outlet of the synthesis tower shell is calculated using the following formula: ) ②, Where: The heat required to heat the outlet gas of the catalyst frame to the outlet temperature. is the enthalpy of the outlet gas leaving the shell of the synthesis tower, is the enthalpy of the outlet gas at the temperature where the inlet gas enters the catalyst frame, is the mass flow rate of the outlet gas (assuming that the material loss in the reactor is ignored, it is equal to the mass flow rate of the inlet gas), is the specific heat capacity of the outlet gas out of the shell of the synthesis tower, is the specific heat capacity of the outlet gas at the temperature where the inlet gas enters the catalyst frame, is the temperature of the outlet gas leaving the shell of the synthesis tower, is the temperature of the outlet gas when the inlet gas enters the catalyst frame, that is equal .

[0052] Then, calculate the heat loss of the synthesis tower to the surrounding environment, the calculation formula is: ③, Where: is the heat loss of the synthesis tower, F is the heat dissipation area of ​​the synthesis tower, is the wall temperature of the synthesis tower, is the ambient temperature, is the heat transfer coefficient of the outer surface of the tower wall to the air, By empirical formula get.

[0053] The energy balance equation of the green ammonia synthesis tower is calculated as follows: ④, in is the heat of reaction.

[0054] The energy balance equation of a high-efficiency heat exchanger is calculated as follows: ) ⑤, Where: is the specific heat capacity of the feed gas entering the high-efficiency heat exchanger, is the specific heat capacity of the discharge gas out of the high-efficiency heat exchanger, is the temperature of the feed gas entering the high-efficiency heat exchanger, is the temperature of the discharge gas leaving the high-efficiency heat exchanger, is the flow rate of the first bypass pipeline.

[0055] Assuming that the bed temperature remains constant under different loads to maintain a stable reaction (the bed temperature remains constant means that the temperature distribution in the ammonia synthesis reaction device (including the ammonia synthesis equipment body and the catalyst bed) is constant or approximately constant compared with the traditional Haber-Bosch ammonia synthesis tower by adjusting the temperature of the inlet gas 101 of the synthesis tower, and the characteristic is that the temperature of the synthesis gas at the outlet of the device remains constant or approximately constant), then the heat loss of the synthesis tower under low load will be consistent with the heat loss under rated load. constant, We use equations ① to ④ to obtain the required inlet gas temperature entering the synthesis tower under different loads. , and then the product of the flow rate of the first bypass pipeline 103 and the temperature difference of the outlet gas entering and leaving the heat exchanger is obtained through the energy balance equation ⑤,

[0056] Right now ).

[0057] In order to satisfy the temperature difference between the two ends of the heat exchanger is greater than 5°C, the conditional equation is obtained: ⑥.

[0058] According to conditional equation ⑥, we get The minimum value for the stable operation of the synthesis tower, the temperature of the outlet gas from the high-efficiency heat exchanger It can be adjusted by bypass regulating valve. At this time, the temperature adjustment needs to meet the condition equation:

[0059] ⑦, If this is not satisfied, it will not be possible to compensate for the heat loss of the synthesis tower by increasing the heat transfer capacity of the high-efficiency heat exchanger 300. That is the adjustment ratio of the first bypass pipeline 103.

[0060] Process operation and analysis under conventional stable production conditions: Embodiment 1: When the 2wt / a synthetic ammonia production unit is in normal stable production state, the high-temperature synthesis gas 102 discharged from its synthetic green ammonia synthesis tower has a temperature of 435℃ and a flow rate of 19120 m 3 / h, feed gas 100 (hydrogen and nitrogen mixed in a certain proportion), initial temperature 140 °C, normal flow rate 22410 m 3 / h.

[0061] The high-temperature synthesis gas 102 discharged from the synthesis tower all passes through the heat recovery unit 302. After testing, the synthesis gas temperature of the feed preheater 303 is still maintained at about 210°C after heat recovery, ensuring that there is enough heat to preheat the feed gas 100 to the required temperature of 180°C for the synthesis tower inlet gas 101.

[0062] At this time, the heat lost by the synthesis tower to the surrounding is calculated by formula ③, where The heat dissipation loss of the synthesis tower is about 68.7kw, of which 21.8w / m 2 ℃, 16.6 m 2 , is 190℃.

[0063] The temperature sensors in the system monitor the temperature of each key position (the inlet and outlet of the synthesis tower and the catalyst frame in the synthesis tower) in real time. Under this working condition, the temperature of the synthesis tower inlet gas 101 is detected to be 180°C, and the temperature of the high-temperature synthesis gas 102 is 435°C, which is consistent with the preset target temperature of 435°C under this stable production condition. The flow rate and pressure data of the synthesis gas and feed gas fed back by the flow sensor and pressure sensor are also in the normal stable range. The controller determines that the system is in a stable operating state based on these real-time data, and there is no need to make additional adjustments to the three-way regulating valve 202. The entire preheating process runs smoothly, providing feed gas with a suitable temperature for the subsequent synthetic ammonia reaction.

[0064] Process operation and analysis when production load is reduced: Embodiment 2: When the 2wt / a synthetic ammonia production unit is in the low-load production state of green power conditions, take 50% load as an example. Assuming that the bed temperature remains unchanged under different loads to maintain the stable reaction, the temperature of the high-temperature synthesis gas 102 discharged from the synthetic green ammonia synthesis tower is still 435℃, and the flow rate is 9559 m 3 / h, feed gas 100 (hydrogen and nitrogen mixed in a certain proportion) initial temperature is 140℃, normal flow rate is 11206 m 3 / h.

[0065] Through the simultaneous equations ①-④, the required temperature of the inlet gas entering the synthesis tower under 50% load is 192°C to maintain the temperature in the green ammonia synthesis tower stable. From equations ⑤~⑦, the adjustment ratio of the first bypass pipeline 103 is 4%, that is, At this time, the high-efficiency heat exchanger 300 ensures that there is enough heat available to preheat the feed gas 100 to the required temperature of 192°C for the synthesis tower inlet gas 101, so that the temperature of the synthesis tower inlet gas is still kept within a constant range when the system load changes. The other high-temperature synthesis gas 102 discharged from the synthesis tower passes through the heat recovery unit 302, and the temperature of the synthesis gas mixture after heat recovery and passing through the high-efficiency heat exchanger 300 is maintained at about 210°C.

[0066] Embodiment three: When the 2wt / a synthetic ammonia production unit is in the low-load production state of green power conditions, take 30% load as an example. Assuming that the bed temperature remains unchanged under different loads to maintain the stable reaction, the temperature of the high-temperature synthesis gas 102 discharged from the synthetic green ammonia synthesis tower is still 435℃, and the flow rate is 5736 m 3 / h, feed gas 100 (hydrogen and nitrogen mixed in a certain proportion) initial temperature is 140℃, normal flow rate is 6723 m 3 / h.

[0067] Through the simultaneous equations ①-④, the required temperature of the inlet gas entering the synthesis tower under 30% load is 203℃ to keep the temperature in the green ammonia synthesis tower stable. From equations ⑤~⑦, the adjustment ratio of the first bypass pipeline 103 is 9.3%, that is, The high-efficiency heat exchanger 300 ensures that there is enough heat available to preheat the feed gas 100 to the required temperature of 203°C for the synthesis tower inlet gas 101. The other high-temperature synthesis gas 102 discharged from the synthesis tower passes through the heat recovery unit 302, and the temperature of the synthesis gas mixture after heat recovery and passing through the high-efficiency heat exchanger 300 is maintained at about 210°C.

[0068] Embodiment three: When the 2wt / a synthetic ammonia production unit is in the low-load production state of green power conditions, take 7% load as an example. Assuming that the bed temperature remains unchanged under different loads to maintain the stable reaction, the temperature of the high-temperature synthesis gas 102 discharged from the synthetic green ammonia synthesis tower is still 435℃, and the flow rate is 1569 m 3 / h, feed gas 100 (hydrogen and nitrogen mixed in a certain proportion), initial temperature 140 °C, normal flow rate 1338 m 3 / h.

[0069] Through the simultaneous equations ①-④, the required temperature of the inlet gas entering the synthesis tower under 7% load is 291°C to maintain the temperature in the green ammonia synthesis tower stable. From equations ⑤~⑦, the adjustment ratio of the first bypass pipeline 103 is 50%, that is, At this time, the high-efficiency heat exchanger 300 ensures that there is enough heat available to preheat the feed gas 100 to the required temperature of 291°C for the synthesis tower inlet gas 101. The other high-temperature synthesis gas 102 discharged from the synthesis tower passes through the heat recovery unit 302, and the temperature of the synthesis gas mixture after heat recovery and passing through the high-efficiency heat exchanger 300 is maintained at about 210°C.

[0070] Embodiment 4: When the 2wt / a synthetic ammonia production unit is in the low-load production state of green power conditions, take 5% load as an example. Assuming that the bed temperature remains unchanged under different loads to maintain the stable reaction, the temperature of the high-temperature synthesis gas 102 discharged from the synthetic green ammonia synthesis tower is still 435℃, and the flow rate is 956 m 3 / h, feed gas 100 (hydrogen and nitrogen mixed in a certain proportion), initial temperature 140 °C, normal flow rate 1120 m 3 / h.

[0071] Through the simultaneous equations ①-④, the required temperature of the inlet gas entering the synthesis tower under 5% load is 340℃ to keep the temperature in the green ammonia synthesis tower stable. From equations ⑤~⑦, the regulation ratio of the first bypass pipeline 103 is 72.7%, that is, The high-efficiency heat exchanger 300 ensures that there is enough heat available to preheat the feed gas 100 to the required temperature of 340°C for the synthesis tower inlet gas 101. The other high-temperature synthesis gas 102 discharged from the synthesis tower passes through the heat recovery unit 302, and the temperature of the synthesis gas mixture after heat recovery and passing through the high-efficiency heat exchanger 300 is maintained at about 210°C.

[0072] In actual industrial production applications, the control process method and related parameters of the present invention can be further optimized and adjusted according to the specific scale, process characteristics and control requirements of different synthetic ammonia production devices, so as to better meet actual production needs, achieve optimal heat utilization and feed gas preheating effects, and help energy conservation, emission reduction and sustainable development of the green ammonia production industry.

[0073] It is particularly suitable for the working condition characteristics of green hydrogen as raw material in the green ammonia synthesis process: volatility, randomness, intermittent "variable load (the load can be as low as 20% or less of the rated load, and as high as 120% or more of the rated load)" working condition to achieve flexible self-heating process control. The present invention uses the high-temperature synthesis gas that has not been heat recovered from the green ammonia synthesis tower to partially or completely bypass the heat recovery method through the heat recovery bypass, so as to flexibly and efficiently preheat the feed gas with the heat generated by the synthesis ammonia reaction, increase the feed temperature to compensate for the heat lost to the surrounding environment through the outer surface of the green ammonia synthesis tower during the production process, so as to achieve the purpose of "constant temperature" or "near constant temperature" operation of the green ammonia synthesis tower, realize the net ammonia value of the synthesis ammonia unchanged operation under the "variable load" working condition, reduce the harsh operating condition requirements for the synthesis tower equipment under the "variable load" working condition, and improve the safety and stability of the operation. The present invention flexibly utilizes heat to preheat the feed gas according to the synthetic ammonia production conditions, and is particularly suitable for low-load conditions of green ammonia synthesis, effectively improving energy utilization efficiency, enhancing process adaptability, and ensuring system safety and reliability, which has positive significance for the sustainable development of the green ammonia production industry.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An intelligent flexible control system for heat recovery from green ammonia synthesis, characterized in that: The invention comprises a bypass regulating system: a first bypass pipeline is arranged in parallel with the green ammonia synthesis heat recovery unit so that the two form a parallel branch, and a flow splitting control unit is arranged upstream of the two parallel branches, and the flow splitting control unit controls the flow of the two parallel branches independently or collaboratively; When the production load changes, the flow splitting control unit adjusts the opening to control part or all of the high-temperature synthesis gas to enter the first bypass pipeline, and intelligently and flexibly distributes and utilizes the heat of the high-temperature synthesis gas; High-efficiency heat exchange system: Use high-efficiency heat exchangers to exchange heat between high-temperature synthesis gas and feed gas; Intelligent flexible control unit: It collects feed flow, feed temperature and system pressure data in real time. As the control end, the intelligent flexible control unit forms a control loop with the diversion control unit. The intelligent flexible control unit adjusts the diversion control unit in real time according to the control signal calculated based on the collected production load information, changes the diversion volume of the first bypass pipeline to match it with the feed gas flow and the heat exchange capacity of the high-efficiency heat exchanger, and keeps the temperature inside the green ammonia synthesis tower stable under various loads.

2. According to claim 1, a green ammonia synthesis heat recovery intelligent flexible control system is characterized in that: The flow splitting control unit is a three-way regulating valve, which changes its opening according to a received control signal to adjust and distribute the flow of the two parallel branches.

3. The green ammonia synthesis heat recovery intelligent flexible control system according to claim 1 is characterized in that: The flow splitting control unit is to respectively set control valves on the two parallel branches, and the control valves on the two parallel branches respectively and independently adjust the flow of the corresponding branches.

4. The green ammonia synthesis heat recovery intelligent flexible control system according to claim 1 is characterized in that: The high-efficiency heat exchanger is any one of a wound tube heat exchanger, a shell and tube heat exchanger, a spiral plate heat exchanger, and a plate-fin heat exchanger; the high-efficiency heat exchanger, the heat recovery unit, and the green ammonia synthesis tower constitute a device, which is a heat pipe reactor or an autothermal reactor.

5. The green ammonia synthesis heat recovery intelligent flexible control system according to claim 1 is characterized in that: The intelligent flexible control unit at least includes a perception layer, a data processing and analysis layer, and a decision-making and control layer; the perception layer includes data acquisition sensors installed at different key positions of the heat recovery flexible control system of the green ammonia synthesis system, including temperature sensors, flow sensors, and pressure sensors; the perception layer collects key parameters in the process in real time, continuously, and accurately, and the key parameters include: the temperature, flow, and pressure of the feed gas, the inlet and outlet temperature, flow, and pressure of the green ammonia synthesis tower, and the temperature of different parts in the green ammonia synthesis tower.

6. According to the green ammonia synthesis heat recovery intelligent flexible control system of claim 5, the data processing and analysis layer at least includes heat calculation of the system, characterized in that: The heat calculation method comprises the following steps: calculating the heat required for the synthesis tower inlet gas to enter the synthesis tower shell and enter the catalyst frame, that is, the heat required for the inlet gas to heat up to the activation temperature, and the calculation formula is as follows: ) ① Where: The heat required to heat the inlet gas of the synthesis tower to the activation temperature. is the enthalpy of the inlet gas entering the catalyst frame, is the enthalpy of the inlet gas entering the shell of the synthesis tower, is the mass flow rate of the inlet gas, is the specific heat capacity of the inlet gas entering the catalyst frame, is the specific heat capacity of the inlet gas entering the shell of the synthesis tower, is the temperature of the inlet gas entering the shell of the synthesis tower, It is the temperature of the inlet gas entering the catalyst frame.

7. The heat calculation according to claim 6, characterized in that: Calculate the heat required to raise the temperature of the synthesis tower outlet gas to the temperature of the synthesis tower shell. The calculation formula is: ) ② Where: The heat required to heat the outlet gas of the catalyst frame to the outlet temperature. is the enthalpy of the outlet gas leaving the shell of the synthesis tower, is the enthalpy of the outlet gas at the temperature where the inlet gas enters the catalyst frame, is the mass flow rate of the outlet gas, is the specific heat capacity of the outlet gas out of the shell of the synthesis tower, is the specific heat capacity of the outlet gas at the temperature where the inlet gas enters the catalyst frame, is the temperature of the outlet gas leaving the shell of the synthesis tower, is the temperature of the outlet gas when the inlet gas enters the catalyst frame, that is equal ; Calculate the heat loss of the synthesis tower to the surrounding environment, the calculation formula is: ③ Where: is the heat loss of the synthesis tower, F is the heat dissipation area of ​​the synthesis tower, is the wall temperature of the synthesis tower, is the ambient temperature, is the heat transfer coefficient of the outer surface of the tower wall to the air, By empirical formula get; The energy balance equation of the green ammonia synthesis tower is calculated as follows: ④ in is the heat of reaction.

8. The heat calculation according to claim 7, characterized in that: The energy balance equation of a high-efficiency heat exchanger is calculated as follows: ) ⑤ Where: is the specific heat capacity of the feed gas entering the high-efficiency heat exchanger, is the specific heat capacity of the discharge gas out of the high-efficiency heat exchanger, is the temperature of the feed gas entering the high-efficiency heat exchanger, is the temperature of the discharge gas leaving the high-efficiency heat exchanger, is the flow rate of the first bypass pipeline.

9. The heat calculation according to claim 8, characterized in that: The simultaneous equations ①~④ give the required inlet gas temperature entering the synthesis tower under different loads , and then the product of the flow rate of the first bypass pipeline and the temperature difference of the outlet gas entering and leaving the heat exchanger is obtained through the energy balance equation ⑤: ); The temperature difference between the two ends of the heat exchanger is not less than 5°C, and the conditional equation is obtained: ⑥ According to conditional equation ⑥, we can get The minimum value to meet the stable operation of the synthesis tower, the temperature of the discharge gas entering the heat exchanger It can be adjusted by the bypass regulating valve; at this time, the temperature adjustment needs to meet the conditional equation: ⑦ If this is not met, it will not be possible to compensate for the heat loss of the synthesis tower by increasing the heat transfer of the high-efficiency heat exchanger. That is, the adjustment ratio of the first bypass pipeline, and the flow splitting control unit is controlled according to the adjustment ratio to adjust the flow passing through the first bypass pipeline.

10. The process control method of a green ammonia synthesis heat recovery intelligent flexible control system according to claim 1, characterized in that: The change in feed load, temperature and pressure data of key system nodes are used as input parameters of the intelligent flexible control unit. After processing and analysis, calculation and modeling, decision-making and control by the intelligent flexible control unit, the control parameters of the diversion control unit matching the actual production load are output. The diversion control unit adjusts the flow of two parallel branches so that the first bypass pipeline diverts a high-temperature synthesis gas flow that matches the feed gas flow and the heat exchange capacity of the high-efficiency heat exchanger, thereby keeping the temperature inside the green ammonia synthesis tower stable under various loads.

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