Intelligent flexible control system for green ammonia synthesis heat recovery

Abstract

The utility model discloses a green ammonia synthesis heat recovery intelligent flexible control system, which is characterized in that a green ammonia synthesis heat recovery unit is provided with a first bypass pipeline in parallel, the upstream of two parallel branches is provided with a shunting control part, and the shunting 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; a control loop is formed by a feeding flow, feeding temperature and analysis system, an intelligent flexible control system and the shunting control part; 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 utility model relates to green ammonia synthesis production technical field, concretely relates to a kind of green ammonia synthesis heat recovery intelligent flexible control system. BACKGROUND

[0002] Ammonia is a very important basic chemical raw material, and has a wide application in modern agriculture, chemical industry and many other fields. At present, it is also developing towards "zero carbon fuel", and it is extremely likely to become an extremely important kind of carbon-reducing fuel in the future. However, its production process is a typical high-energy consumption process, which consumes a large amount of energy resources, mainly due to the high temperature, high pressure and material processing required by ammonia synthesis reaction. In the traditional ammonia synthesis production process, although a large amount of heat is generated, for example, the high-temperature synthesis gas from the synthesis tower carries considerable heat, but the recovery and utilization efficiency of these heat is often unsatisfactory under green electricity conditions. At present, although some traditional processes recover the synthesis heat to preheat the feed gas, these traditional processes are almost operated stably under stable feed quantity, and the process cannot be randomly and flexibly adjusted, so it is difficult to make timely and effective adjustment according to the frequently changing conditions (such as production load fluctuation, raw material gas composition and flow variation) in the production process under the scene of green electricity producing green hydrogen and green hydrogen producing green ammonia. If additional energy is invested to heat the feed gas, it not only increases the production cost, but also does not meet the current requirements of green low-carbon and sustainable development of industry.

[0003] The existing synthetic ammonia feed gas preheating process mostly adopts relatively fixed process and control mode, and the utilization of heat is not accurate and flexible. For example, the prior art: application number CN201520661480.6 discloses an ammonia synthesis tower waste heat recovery and utilization system, the synthesis gas outlet of the ammonia synthesis tower is connected with the synthesis gas inlet of the synthesis medium pressure boiler, the synthesis gas outlet of the synthesis medium pressure boiler is connected with the synthesis gas inlet of the synthesis secondary medium pressure boiler, and then is connected with the heat source inlet of the feed water preheater. The hot water preheated by the feed water preheater passes through the boiler water outlet to the synthesis medium pressure boiler and the synthesis secondary medium pressure boiler, and the heat source outlet of the feed water preheater is connected with the heat source inlet of the tower heat exchanger. The technology adopts a relatively fixed process and control mode. On the one hand, such process design does not fully consider the dynamic changes of heat supply and demand under variable conditions, and the preheating temperature and heat distribution cannot be adjusted in real time according to the actual situation. Under the condition of variable production feed load, the feed gas may be insufficiently preheated or excessively preheated, 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 cannot be fully utilized, causing waste of energy and increasing production cost. At the same time, it is also contrary to the current industrial development concept of green low carbon, energy saving and emission reduction. Under variable load conditions, the traditional process often causes harsh operating conditions for the synthesis tower, such as frequent and large-scale adjustment of the temperature, pressure and material flow of the synthesis tower, which not only increases the operation risk of the synthesis tower equipment, such as thermal stress fatigue, local reaction abnormality caused by uneven material distribution, but also reduces the service life and safety and reliability of the equipment.

[0004] Due to the fluctuation characteristics of new energy such as wind power and photovoltaic, the fluctuation of wind turbine output power and wind speed, and the influence of meteorological conditions on photovoltaic power generation system, the power generation power fluctuates, and the production of green hydrogen using wind power, photovoltaic and other new energy also fluctuates, which causes the problem of "load following source". In order to match the synthesis of green ammonia with the production of green hydrogen and realize "load following source", patent application number CN202410021111.4 discloses a new energy hydrogen production dynamic green ammonia synthesis system and its operation method. The system is provided with multiple ammonia synthesis adjustment towers, multiple heat exchangers and multiple adjustment valves; each device is connected according to the system operation process. Although it realizes variable load adjustment of the green ammonia synthesis system, the structure is complex, different sizes of green ammonia synthesis towers are set to correspond to different production loads, the equipment construction cost increases greatly, the pipeline is complex, the operation personnel's proficiency and adaptability are required to be high, the operation failure rate is high, and the automatic control performance is poor.

[0005] Therefore, it is urgent to timely and flexibly cope with various working condition changes in the ammonia synthesis process, and deeply process and analyze, and make decisions and control the process to realize continuous optimization of the green ammonia synthesis process, so as to meet the scenes of green electricity to green hydrogen, green hydrogen to green ammonia, and meanwhile improve the energy utilization level and overall economic benefits of green ammonia production.

[0006] In view of the above, the utility model discloses a kind of to utilize the synthesis gas directly preheating feedstock gas from green ammonia synthesis tower without heat recovery, combine intelligent flexible control process method to solve the above problems. Utility model contents

[0007] The utility model is to overcome the defects in the prior art, and provide a kind of green ammonia synthesis heat recovery intelligent flexible control system.

[0008] To achieve the above object, the technical scheme of the utility model is as follows: a kind of green ammonia synthesis heat recovery intelligent flexible control system, including ammonia synthesis tower, the feed pipe that enters ammonia synthesis tower, the discharge pipe that leaves ammonia synthesis tower, the discharge pipe is divided into two parallel branch roads, two branch roads are heat utilization pipe and first bypass pipe respectively, two the flow of two parallel branch roads is controlled by shunt control part in upstream end branch road two branches;

[0009] The high-temperature synthesis gas shunted by the first bypass pipe is used as a heat source to perform two-stage heat exchange on the feed gas;

[0010] The downstream end of the first bypass pipe is connected to the heat utilization pipe to perform one-stage heat exchange on the feed gas;

[0011] The heat utilization pipe is provided with a heat recovery unit.

[0012] Further, the one-stage heat exchange is a feed preheater arranged on the feed pipe, the feed gas is used as a cold source of the feed preheater, and the first bypass pipe and the heat utilization pipe are connected to be used as a heat source of the feed preheater.

[0013] Further, the two-stage heat exchange is a high-efficiency heat exchanger arranged at the rear end of the feed preheater, the feed gas is used as a cold source of the feed preheater, and the high-temperature synthesis gas of the first bypass pipe is used as a heat source.

[0014] Further, the shunt control part is a three-way regulating valve.

[0015] Further, the shunt control part is provided with a control valve on each of the two parallel branch roads, and the control valves on the two parallel branch roads independently adjust the flow of the corresponding branch road.

[0016] Further, the high-efficiency heat exchanger and the heat recovery unit are integrated into one device with the ammonia synthesis tower.

[0017] Further, the one device is a heat pipe reactor or a self-heating reactor.

[0018] Further, the feed pipe is provided with a second bypass pipe, which is provided in parallel with the feed preheater and the high-efficiency heat exchanger as a bypass thereof, and a temperature control valve is arranged on the second bypass pipe.

[0019] Further, a temperature control sensor for measuring the temperature of the inlet gas of the synthesis tower is arranged at the top inlet of the ammonia synthesis tower, and the temperature control sensor is electrically connected with the temperature regulating valve to form a control loop in which the valve opening degree is controlled by the temperature parameter.

[0020] Further, a flow sensor is arranged on the feed pipe, and the flow sensor and the temperature control sensor are electrically connected with the three-way regulating valve to form a control loop in which the three-way regulating valve opening degree is controlled by the total inlet flow as a first parameter and the synthesis tower inlet gas temperature as a second parameter.

[0021] Further, a temperature transmission sensor for measuring the temperature of the high-temperature synthesis gas is arranged on the outlet pipe, a first temperature sensor is arranged between the feed preheater and the high-efficiency heat exchanger, a second temperature sensor for measuring the temperature of the catalyst frame is arranged on the ammonia synthesis tower, a third temperature sensor is arranged on the first bypass pipe downstream of the high-efficiency heat exchanger, and a fourth temperature sensor is arranged on the first bypass pipe and the heat utilization pipe confluence pipe.

[0022] The advantages and beneficial effects of the utility model lie in:

[0023] 1. Enhancing process self-adaptability: whether the production load frequently changes, the raw material gas characteristics change or other complex working condition changes, the intelligent flexible control system and method can effectively respond. The intelligent flexible control system is matched with advanced methods such as big data analysis, machine learning algorithm, fuzzy logic control, expert intelligent control, neural network adaptive control and optimization algorithm, can evaluate the performance of the process under different working conditions in real time, flexibly and efficiently realize the preheating of the heat generated by the synthesis ammonia reaction to the feed gas, improve the feed temperature to make up for the heat lost to the surrounding environment through the outer surface of the ammonia synthesis tower in the production process, so as to achieve the purpose of "constant temperature" or "near constant temperature" operation of the ammonia synthesis tower, realize the constant operation of the net ammonia value of the synthesized ammonia under the "variable load" working condition, reduce the harsh operation working condition requirement of the synthesis tower equipment under the "variable load" working condition, improve the safety and stability of the operation. Further optimization provides intelligent control basis to ensure that the feed gas preheating temperature is always stable in the range of the best reaction conditions of the synthesized ammonia, so as to ensure the efficient performance of the green ammonia synthesis reaction and improve the adaptability and running stability of the whole process to different working conditions.

[0024] 2. Improve energy utilization efficiency: through the intelligent flexible control system and method, the heat resources can be flexibly allocated according to the actual working condition of green ammonia production, the feed gas is accurately preheated, the demand for additional energy for heating the feed gas is maximally reduced, the energy utilization efficiency of the entire green ammonia production system is significantly improved, the production cost is reduced, and the industrial requirements of energy saving and emission reduction and sustainable development are met;

[0025] 3. Improve equipment safety performance and service life: in the traditional synthetic ammonia process, variable load conditions often make the ammonia synthesis tower face harsh operating conditions (such as frequent fluctuations of temperature, pressure and material flow) and serious equipment fatigue problems, the safety performance is challenged and the service life is shortened. The intelligent flexible control system and method has obvious advantages, through accurate regulation and control of each link, the alternating load of the equipment is effectively reduced. During variable load, the flow, temperature and other key parameters of the synthesis gas and the feed gas can be quickly and intelligently adjusted according to the real-time conditions, the sharp fluctuation of the key parameters of the synthesis tower is prevented, the harsh operating requirements of the synthesis tower equipment are greatly reduced, the equipment fatigue degree is significantly reduced, the equipment safety performance is greatly improved, the equipment service life is prolonged, the equipment maintenance frequency and cost are reduced, and the stability and reliability of the entire synthetic ammonia production system under different working conditions are enhanced, which provides strong support for the efficient and sustainable development of the synthetic ammonia industry.

[0026] 4. Optimize process and continuously improve: the intelligent flexible control system and method can comprehensively, deeply and real-timely analyze the process, provide detailed information from multiple dimensions such as energy balance, heat transfer process and working condition adaptability, and provide a scientific basis for the continuous optimization of the process. 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, which brings continuous energy saving and consumption reduction advantages to green ammonia production. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a process flow chart of the intelligent flexible control system for green ammonia synthesis heat recovery of the utility model;

[0028] Figure 2 is an energy balance analysis diagram of the intelligent flexible control system for green ammonia synthesis heat recovery in the utility model;

[0029] Figure 3 is a process control diagram of the intelligent flexible control system for green ammonia synthesis heat recovery in the utility model;

[0030] 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, split control part; 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

[0031] The specific embodiments of the present application will be further described below in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0032] A green ammonia synthesis heat recovery intelligent flexible control system, as shown in Figures 1-2 The green ammonia synthesis tower 301, the feed pipeline into the green ammonia synthesis tower 301, and the discharge pipeline out of the green ammonia synthesis tower 301 are provided. The discharge pipeline is divided into two parallel branch roads, which are the heat utilization pipeline 104 and the first bypass pipeline 103. The heat utilization pipeline 104 is provided with a heat recovery unit 302.

[0033] The two parallel branch roads are controlled by a split control part at the upstream end to control the flow rate of the two branch roads. The split control part is a three-way regulating valve 202. The high-temperature synthesis gas 102 split by the first bypass pipeline 103 is used as a heat source to perform two-stage heat exchange on the feed gas 100. The downstream end of the first bypass pipeline 103 is connected to the heat utilization pipeline 104 to perform one-stage heat exchange on the feed gas 100.

[0034] In actual use, the feed gas 100 is gradually heated by the first heat exchange and the second heat exchange in turn, and then reaches the temperature of the green ammonia synthesis tower inlet gas 101, so as to meet the reaction conditions of the material in the green ammonia synthesis tower 301. It can be understood that the first heat exchange is that the high-temperature synthesis gas is used to preheat the feed gas 100 after passing through the heat recovery unit 302. When the load decreases, the flow of the high-temperature synthesis gas 102 also decreases correspondingly. 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 pipe 103 provided in the process divides 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 the second heat exchange on the feed gas 100, so as to further increase the temperature of the feed gas and be sufficient to maintain the temperature in the green ammonia synthesis tower stable. Thus, the system can always maintain the stability of the internal temperature of the green ammonia synthesis tower when facing different loads, and thus ensure the reaction efficiency.

[0035] Specifically, the first heat exchange is a feed preheater 303 arranged on the feed pipe, the feed gas 100 is used as the cold source of the feed preheater 303, and the first bypass pipe 103 and the heat utilization pipe 104 are converged as the heat source of the feed preheater 303. The second heat exchange is a high-efficiency heat exchanger 300 arranged at the rear end of the feed preheater 303, the feed gas 100 is used as the cold source of the feed preheater 303, and the high-temperature synthesis gas 102 of the first bypass pipe 103 is used as the heat source. As an embodiment, as shown in Figure 1 、 3 The high-efficiency heat exchanger 300 and the heat recovery unit 302 are arranged independently 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 be used to replace the arrangement.

[0036] As another embodiment, the high-efficiency heat exchanger 300 and the heat recovery unit 302 are integrated with the green ammonia synthesis tower 301 as one device (not shown in the figure). Specifically, a heat pipe reactor or a self-heating reactor, or other structural type reactors can be used. In actual use, the type of the reactor is not limited and other structural type reactors can be used to replace the arrangement.

[0037] Further, the feed pipeline is provided with a second bypass pipeline which is provided in parallel with the feed preheater 303 and the high-efficiency heat exchanger 300 as a bypass of the feed preheater 303 and the high-efficiency heat exchanger 300, and a temperature control regulating valve 601 is arranged on the second bypass pipeline. A temperature control sensor 201 for measuring the temperature of the synthesis tower inlet gas 101 is arranged at the top inlet of the green ammonia synthesis tower 301, and the temperature control sensor 201 and the temperature regulating valve are electrically connected to form a control loop for controlling the valve opening degree according to the temperature parameter. As a control mode, when the temperature control sensor 201 monitors that the temperature of the synthesis tower inlet gas 101 is higher than the calculated temperature range corresponding to the production load, the temperature control regulating valve 601 is opened to a certain opening degree through the control loop, so that the feed gas 100 with low temperature is mixed with the feed gas 100 after secondary heat exchange to reduce the temperature, the control when the temperature is high is realized, and then the temperature of the synthesis tower inlet gas 101 is kept consistent with the temperature required by calculation corresponding to the load when the production load is changed, and then the temperature in the green ammonia synthesis tower is maintained stable.

[0038] Further, a flow sensor 200 is arranged on the feed pipeline, the flow sensor 200 and the temperature control sensor 201 are electrically connected with a three-way regulating valve 202 to form a control loop for controlling the opening degree of the three-way regulating valve 202 according to the total inlet flow as a first parameter and the temperature of the synthesis tower inlet gas 101 as a second parameter. When the system load is reduced, the opening degree of the three-way regulating valve 202 is controlled according to the feedback parameters of the flow sensor 200 and the temperature control sensor 201 and combined with the calculation data of the system analysis, so that the flow of the corresponding high-temperature synthesis gas 102 enters the first bypass pipeline 103, thereby the high-temperature synthesis gas not passing through the heat recovery unit 302 is directly used for warming up the feed gas 100, and then the temperature of the synthesis tower inlet gas 101 is relatively increased, and then the temperature in the green ammonia synthesis tower is kept stable at low load.

[0039] Further, a temperature transmission sensor 602 for measuring the temperature of the high-temperature synthesis gas 102 is arranged on the discharge pipeline; a first temperature sensor 603 is arranged between the feed preheater 303 and the high-efficiency heat exchanger 300; a second temperature sensor 604 for measuring the temperature of the catalyst frame 401 is arranged on the green ammonia synthesis tower 301; a third temperature sensor 605 is arranged downstream of the high-efficiency heat exchanger 300 on the first bypass pipeline 103; and a fourth temperature sensor 606 is arranged on the confluence pipeline of the first bypass pipeline 103 and the heat utilization pipeline 104. Each temperature sensor is used for monitoring the running state of the system.

[0040] The specific control steps are as follows:

[0041] The utility model mainly by bypass adjustment, high -efficient heat exchange, intelligent flexible control system three parts constitute, and realize the high -efficient flexible use of heat through mutual coordination:

[0042] A first bypass pipe 103 and a corresponding regulating valve are arranged in the heat recovery unit 302. When special conditions (such as production load fluctuation, raw material gas composition and flow variation, heat exchanger failure, etc.) are encountered, the bypass valve opening can be adjusted to partially or completely bypass the heat recovery unit 302, thereby achieving rapid emergency control of the temperature of the synthetic tower inlet gas 101 and ensuring the safety and stability of the entire system.

[0043] Meanwhile, the high-efficiency heat exchanger 300 is used to realize heat transfer from the high-temperature synthesis gas 102 to the feed gas 100. The type of heat exchanger can be selected according to actual process requirements and working condition characteristics, such as a shell-and-tube heat exchanger, a spiral plate heat exchanger, or a plate-fin heat exchanger, etc. The high-efficiency heat exchanger 300 and the heat recovery unit 302 can be independent of the green ammonia synthesis tower 301, or they can form a device such as a heat pipe reactor or a self-heating reactor. The design heat exchange area of the heat exchanger is determined based on the overall process energy balance calculation, and the heat exchange requirements under different production loads should be fully considered to ensure that the feed gas 100 preheating requirements can be met under various working conditions.

[0044] The feed gas 100 (containing hydrogen and nitrogen raw material gas) is supplied from its respective gas source. Before entering the feed preheater 303, its initial temperature is low, and the flow will change with production load, process adjustment, and other factors. 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 pipe, and a temperature control sensor 201 is provided on the synthetic tower inlet gas 101 pipe. When the load is low, the three-way regulating valve 202 is used. The regulating valve adjusts the flow of the first bypass pipe 103 in real time according to the production load and the information fed back from the analysis system, so that it matches the flow of the feed gas 100 and the heat exchange capacity of the high-efficiency heat exchanger 300. For example, if the feed gas 100 flow is lower than the rated flow, the controller will increase the opening of the three-way regulating valve 202, so that more high-temperature synthesis gas 102 enters the high-efficiency heat exchanger 300, increasing the heat transfer, thereby increasing the preheating temperature of the feed gas 100, and further increasing the temperature of the synthetic tower inlet gas 101. During the process of increasing the temperature of the synthetic tower inlet gas, if the temperature is higher than the target temperature, the synthesis gas flow regulating valve opening should be appropriately reduced.

[0045] The aforementioned regulating method can also be used for auxiliary regulation, that is, when the temperature of the synthetic tower inlet gas exceeds the calculated temperature quickly and still has a rising trend, the opening of the temperature control regulating valve 601 can be used to quickly cool the temperature of the synthetic tower inlet gas. It can be understood that the priority of the three-way regulating valve 202 is higher than that of the temperature control regulating valve 601.

[0046] The intelligent flexible control system based on advanced methods such as big data analysis, machine learning algorithm, fuzzy logic control, expert intelligent control, neural network adaptive control and optimization algorithm is used to realize intelligent flexible control of the entire green ammonia synthesis heat recovery system. The intelligent flexible control system 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), and a decision and control layer composed of an actuator (a regulating valve).

[0047] In addition, during the preheating of the feed gas 100, to prevent the temperature of the green ammonia synthesis tower inlet gas 101 from being too high due to failure of the intelligent flexible control system or other abnormal conditions, an over-temperature protection device is arranged 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, opens 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, avoiding damage to the subsequent green ammonia synthesis ammonia reaction catalyst and equipment caused by high temperature.

[0048] As another embodiment:

[0049] The shunt control part 204 is provided with a control valve 203 on each of the two parallel branches, and the control valves 203 on the two parallel branches independently adjust the flow of the corresponding branch. The two independently arranged control valves 203 realize independent, high-precision and accurate control of each branch. In the foregoing embodiment, the shunt control part 204 adopts the form of a three-way regulating valve 202. In actual use, the shunt control part 204 can also be divided into multiple control valves 203. Specifically, as shown in Figure 3 The high-temperature synthesis gas 102 is branched into two parallel branches, and an automatically controllable control valve 203 is arranged on each branch. The two valves are independently controlled to more accurately shunt the high-temperature synthesis gas 102.

[0050] As an embodiment of the intelligent flexible control system, specifically, it is composed of at least three layers of perception layer, data processing and analysis layer, and decision and control layer.

[0051] The perception layer is composed of inlet and outlet flow sensors, inlet and outlet temperature sensors, and inlet and outlet pressure sensors, and is the basis of the entire intelligent flexible control system. The sensors monitor the production, transmission and consumption states in the system in real time, for example, the inlet and outlet flow sensors can obtain the real-time flow change of the inlet and outlet, and the temperature sensors can obtain the real-time temperature change in the system. The data collected by the sensors include flow, pressure, temperature and other parameters, which provide the basis for subsequent analysis and control.

[0052] The collected data is aggregated to the data processing and analysis layer for processing. First, the data needs to be cleaned to remove outliers and erroneous data. Then, based on various applicable physical and chemical laws and rules, formulas, such as the first law of thermodynamics (i.e., the law of conservation of energy), Van't Hoff equation, and Arrhenius formula, a model is established, and then data analysis techniques such as big data analysis, machine learning algorithms, etc. are used to mine the rules and potential information in the data, fit various applicable physical and chemical laws and rules, formulas, so that the physical constant values are more accurate and effective, and the model can better predict, real-time, and effectively control the intelligent control of green ammonia synthesis. For example, by analyzing the historical and real-time data of the inlet and outlet temperature and flow rate of the feed, the trend of the inlet and outlet temperature and flow rate of the feed can be predicted, providing a reference for the rational scheduling of the control of the first bypass flow distribution; analyzing the energy balance and temperature distribution data in the green ammonia synthesis tower in the green ammonia synthesis heat recovery intelligent flexible control system can optimize the temperature setting of the preheated feed gas to optimize the temperature distribution in the green ammonia synthesis tower, improve the net ammonia value and catalyst life.

[0053] Based on the results obtained from 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 algorithms, and is completed by the shunt controller to make decisions and control the execution. For the green ammonia synthesis heat recovery intelligent flexible control system, the decision involves the coordination and scheduling of the feed flow change and the shunt control part. For example, when the feed quantity decreases, the proportion of the shunt control part to the first bypass flow can be increased, and at the same time the system operating mode can be adjusted 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, make up for the heat loss of the green ammonia synthesis tower, and keep the temperature in the green ammonia synthesis tower stable regardless of the change in the feed quantity.

[0054] Computing method of intelligent flexible control system:

[0055] The computing method matched with the above flexible process aims to comprehensively, deeply, and real-time analyze the process, provide data support and decision basis for the stable operation of the intelligent flexible control system, and mainly includes the following contents:

[0056] Through various sensors (temperature sensors, flow sensors 200, etc.) installed at different key positions, real-time, continuous, and accurate collection of key parameter data in the process is realized. These data include but are not limited to: temperature, flow rate, and pressure of the feed gas 100, inlet and outlet temperature, flow rate, and pressure of the green ammonia synthesis tower 301, temperature distribution at different positions in the green ammonia synthesis tower 301, etc. The data collected by the sensors has a high frequency to ensure that subtle changes in the process can be captured, providing rich and accurate raw data for subsequent analysis.

[0057] Based on the real-time data collected, the energy balance algorithm is embedded in the intelligent flexible control system to perform energy balance analysis and control the three-way regulating valve 202 in real time. The specific calculation method is as follows:

[0058] First, the heat required for the inlet gas of the synthesis tower to enter the synthesis tower shell to enter the catalyst frame, i.e. the heat for the inlet gas to rise to the activation temperature, is calculated according to the formula

[0059] ) ①,

[0060] In the formula: Q1 is the heat for the inlet gas of the synthesis tower to rise to the activation temperature,

[0061] H1 is the enthalpy of the inlet gas entering the catalyst frame,

[0062] H0 is the enthalpy of the inlet gas entering the synthesis tower shell,

[0063] m0 is the mass flow rate of the inlet gas,

[0064] Cp1 is the specific heat capacity of the inlet gas entering the catalyst frame (calculated according to the composition and temperature of the synthesis gas by referring to relevant thermodynamic data tables or empirical formula),

[0065] Cp0 is the specific heat capacity of the inlet gas entering the synthesis tower shell,

[0066] T0 is the temperature of the inlet gas entering the synthesis tower shell,

[0067] T1 is the temperature of the inlet gas entering the catalyst frame.

[0068] Then, the heat for the outlet gas of the catalyst frame to rise to the temperature of the outlet of the synthesis tower shell is calculated, and the calculation formula is

[0069] ) ②,

[0070] In the formula: Q2 is the heat for the outlet gas of the catalyst frame to rise to the temperature of the outlet of the synthesis tower shell,

[0071] H2 is the enthalpy of the outlet gas exiting the synthesis tower shell,

[0072] H1 is the enthalpy of the outlet gas at the temperature at which the inlet gas enters the catalyst frame,

[0073] m0 is the mass flow rate of the outlet gas (assuming that the material loss in the reactor is not considered, which is equal to the mass flow rate of the inlet gas),

[0074] Specific heat capacity of the outlet gas leaving the synthesis column shell,

[0075] Specific heat capacity of the outlet gas at the temperature at which the inlet gas enters the catalyst frame,

[0076] Temperature of the outlet gas leaving the synthesis column shell,

[0077] Temperature of the outlet gas at the temperature at which the inlet gas enters the catalyst frame, i.e. is equal to .

[0078] Then, the heat lost by the synthesis column to the surroundings is calculated by the formula

[0079] ③,

[0080] In the formula: is the heat loss of the synthesis column,

[0081] F is the heat dissipation area of the synthesis column,

[0082] is the temperature of the synthesis column wall,

[0083] is the ambient temperature,

[0084] is the heat transfer coefficient of the outer surface of the column wall to the air,

[0085] is obtained from the empirical formula .

[0086] The calculation formula of the energy balance equation of the green ammonia synthesis column is

[0087] ④,

[0088] where is the heat of reaction.

[0089] The calculation formula of the energy balance equation of the high-efficiency heat exchanger is:

[0090] ) ⑤,

[0091] In the formula: is the specific heat capacity of the feed gas entering the high-efficiency heat exchanger,

[0092] is the specific heat capacity of the outlet gas leaving the high-efficiency heat exchanger,

[0093] temperature of the feed gas into the high-efficiency heat exchanger,

[0094] temperature of the discharge gas out of the high-efficiency heat exchanger,

[0095] flow rate of the first bypass pipe.

[0096] Assuming that the bed temperature is constant at different loads to maintain the reaction stable (the constant bed temperature means that the temperature distribution in the ammonia synthesis reactor (including the ammonia synthesis equipment body and the catalyst bed) is constant or approximately constant compared with the traditional Haber-Bosch method for synthesizing ammonia tower, and the characteristic is that the outlet synthesis gas temperature of the device is constant or approximately constant), the heat loss of the synthesis tower at low load will be consistent with the heat loss at rated load, constant, constant. We get the temperature of the inlet gas into the synthesis tower at different loads by solving equations ①~④ , and the flow rate of the first bypass pipe 103 and the product of the temperature difference of the discharge gas into the heat exchanger by energy balance equation ⑤,

[0097] that is, ).

[0098] In order to meet the temperature difference of more than 5℃ at both ends of the heat exchanger, the condition equation is obtained:

[0099] ⑥.

[0100] According to condition equation ⑥, the minimum value that meets the stable operation of the synthesis tower, the temperature of the discharge gas out of the high-efficiency heat exchanger can be adjusted by the bypass regulating valve. At this time, the adjustment temperature needs to meet the condition equation:

[0101] ⑦,

[0102] If it does not meet, the heat loss of the synthesis tower cannot be compensated by increasing the heat transfer amount of the high-efficiency heat exchanger 300, that is, the adjustment ratio of the first bypass pipe 103.

[0103] Process operation and analysis under conventional stable production conditions:

[0104] Example one:

[0105] When the 2wt / a ammonia synthesis production device is in a conventional stable production state, the high-temperature synthesis gas 102 discharged from the synthesis green ammonia synthesis tower has a temperature of 435℃ and a flow rate of 19120 m 3 / h, the initial temperature of the feed gas 100 (hydrogen and nitrogen mixed in a certain proportion) is 140℃, and the normal flow is 22410 m 3 / h.

[0106] The high-temperature synthesis gas 102 discharged from the synthesis tower passes through the heat recovery unit 302 in its entirety. After detection and heat recovery, the temperature of the synthesis gas remains at about 210℃ after passing through the feed preheater 303, ensuring that there is sufficient heat available to preheat the feed gas 100 to the required temperature of 180℃ at the inlet of the synthesis tower 101.

[0107] At this time, the heat loss of the synthesis tower to the surroundings is calculated by formula (3), where is the heat loss of the synthesis tower to the surroundings, about 68.7kw, where is 21.8w / m 2 ·℃, is 16.6 m 2 , is 190℃.

[0108] The temperature sensors in the system monitor the temperature at each key position (the inlet and outlet of the synthesis tower and the catalyst frame inside the synthesis tower) in real time. In this case, the temperature of the feed gas 101 at the inlet of the synthesis tower is detected to be 180℃, and the temperature of the high-temperature synthesis gas 102 is 435℃, which is consistent with the target temperature of 435℃ under the stable production condition as pre-set. The flow and pressure data of the synthesis gas and the feed gas fed back by the flow and pressure sensors are also within the normal stable range. The controller determines that the system is in a stable operating state based on these real-time data, and no additional adjustment is required for the three-way regulating valve 202. The entire preheating process runs smoothly, providing feed gas with a suitable temperature for the subsequent synthesis ammonia reaction.

[0109] Process operation and analysis when the production load is reduced:

[0110] Example Two:

[0111] When the 2wt / a synthesis ammonia production device is in a low-load production state under green electricity conditions, take 50% load as an example. Assuming that the bed temperature remains unchanged under different loads to maintain stable reaction, the temperature of the high-temperature synthesis gas 102 discharged from the green ammonia synthesis tower remains 435℃, and the flow is 9559 m 3 / h, the initial temperature of the feed gas 100 (hydrogen and nitrogen mixed in a certain proportion) is 140℃, and the normal flow is 22410 m 3 / h.

[0112] Through simultaneous equations (1)-(4), the required temperature of the inlet gas entering the synthesis tower under 50% load is 192℃ to maintain the temperature stability in the green ammonia synthesis tower. According to equations (5)-(6), the adjustment ratio of the first bypass pipe 103 is 4%, i.e. At 4%, the high-efficiency heat exchanger 300 ensures sufficient heat for preheating the feed gas 100 to the required temperature of 192°C for the synthesis tower inlet gas 101, thus maintaining the temperature of the synthesis tower inlet gas within a constant range even when the system load changes. The high-temperature synthesis gas 102 discharged from the synthesis tower passes through the heat recovery unit 302, and after heat recovery, the temperature of the mixture with the synthesis gas passing through the high-efficiency heat exchanger 300 is maintained at approximately 210°C.

[0113] Example 3:

[0114] When a 2 wt / a ammonia synthesis unit operates at a low load under green electricity conditions, taking 30% load as an example, assuming that the bed temperature remains constant under different loads to maintain stable reaction, the high-temperature synthesis gas 102 discharged from the ammonia synthesis tower will still have a temperature of 435℃ and a flow rate of 5736 m³ / h. 3 The feed gas volume is 100 m³ / h (hydrogen and nitrogen mixed in a certain proportion), the initial temperature is 140℃, and the normal flow rate is 6723 m³ / h. 3 / h.

[0115] By solving equations ①-④, the required temperature of the inlet gas entering the synthesis tower under 30% load is 203℃ to maintain a stable temperature inside the green ammonia synthesis tower. From equations ⑤-⑦, the adjustment ratio of the first bypass pipe 103 is 9.3%, i.e. At 9.3%, sufficient heat is ensured by the high-efficiency heat exchanger 300 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 after heat recovery, the temperature of the mixture with the synthesis gas after passing through the high-efficiency heat exchanger 300 is maintained at approximately 210°C.

[0116] Example 3:

[0117] When a 2 wt / a ammonia synthesis unit operates under low-load conditions with green electricity, taking 7% load as an example, and assuming that the bed temperature remains constant under different loads to maintain stable reaction, the high-temperature synthesis gas 102 discharged from the ammonia synthesis tower will still have a temperature of 435℃ and a flow rate of 1569 m³ / h. 3 The feed gas volume is 100 m³ / h (a mixture of hydrogen and nitrogen in a certain proportion), the initial temperature is 140℃, and the normal flow rate is 1338 m³ / h. 3 / h.

[0118] By solving equations ①-④, the required temperature of the inlet gas entering the synthesis tower under 7% load is 291℃ to maintain a stable temperature inside the green ammonia synthesis tower. From equations ⑤-⑦, the adjustment ratio of the first bypass pipe 103 is 50%, i.e. is 50%, at this time, through the high-efficiency heat exchanger 300, it is ensured that there is enough heat available for the feed gas 100 to be preheated to the required temperature 291℃ of the inlet gas 101 of the synthesis tower. The high-temperature synthesis gas 102 discharged from the synthesis tower is subjected to the heat recovery unit 302, and after heat recovery, the mixed temperature of the synthesis gas passing through the high-efficiency heat exchanger 300 is maintained at about 210℃.

[0119] Example Four:

[0120] When the 2wt / a synthetic ammonia production device is in a low-load production state of green electricity working condition, taking 5% load as an example. Assuming that the bed temperature remains unchanged at different loads to maintain stable reaction, the temperature of the high-temperature synthesis gas 102 discharged from the green ammonia synthesis tower is still 435℃, and the flow rate is 956 m 3 / h, the initial temperature of the feed gas 100 (hydrogen and nitrogen mixed in a certain proportion) is 140℃, and the normal flow rate is 1120 m 3 / h.

[0121] By simultaneous equations ①-④, the required temperature of the inlet gas entering the synthesis tower at 5% load is 340℃ to maintain the temperature stability in the green ammonia synthesis tower, and by equations ⑤~⑦, the adjustment ratio of the first bypass pipe 103 is 72.7%, that is 72.7%, at this time, through the high-efficiency heat exchanger 300, it is ensured that there is enough heat available for the feed gas 100 to be preheated to the required temperature 340℃ of the inlet gas 101 of the synthesis tower. The high-temperature synthesis gas 102 discharged from the synthesis tower is subjected to the heat recovery unit 302, and after heat recovery, the mixed temperature of the synthesis gas passing through the high-efficiency heat exchanger 300 is maintained at about 210℃.

[0122] In actual industrial production applications, the control process method and related parameters of the utility model 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 the actual production requirements, realize the best heat utilization and feed gas preheating effect, and help the energy saving and emission reduction and sustainable development of the green ammonia production industry.

[0123] The utility model is especially suitable for the working condition characteristics of using green hydrogen as raw material in green ammonia synthesis process: fluctuation, randomness, intermittent "variable load (the load can be as low as 20% of rated load and below, and can be as high as 120% of rated load and above)" condition realizes flexible self-heating process control. The utility model uses the high-temperature synthesis gas which is not recovered from the green ammonia synthesis tower to bypass the heat recovery mode by part or all of the bypass, flexibly and efficiently realizes the heat generated by the synthesis ammonia reaction to preheat the feed gas, improves the feed temperature to make up the heat lost to the surrounding environment through the outer surface of the green ammonia synthesis tower in the production process, achieves the purpose of "constant temperature" or "near constant temperature" operation of the green ammonia synthesis tower, realizes the constant net ammonia value of the synthesized ammonia under the "variable load" condition, reduces the harsh operation condition requirements of the synthesis tower equipment under the "variable load" condition, and improves the safety and stability of the operation. The utility model flexibly uses heat to preheat the feed gas according to the ammonia synthesis production condition, is especially suitable for the low load condition of green ammonia synthesis, effectively improves the energy utilization efficiency, enhances the process adaptability and guarantees the safety and reliability of the system, has a positive significance for the sustainable development of the green ammonia production industry.

[0124] The above is only the preferred embodiment of the utility model, and it should be pointed out that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the technical principles of the utility model, and these improvements and refinements should also be regarded as the protection range of the utility model.

Claims

1. A smart flexible control system for heat recovery in green ammonia synthesis, comprising an ammonia synthesis tower, a feed pipe entering the ammonia synthesis tower, and a discharge pipe leaving the ammonia synthesis tower, characterized in that, The discharge pipeline is divided into two parallel branch lines, namely a heat utilization pipeline and a first bypass pipeline. The flow rate of the two parallel branch lines is controlled by the flow control unit at the upstream end. The high-temperature synthesis gas diverted from the first bypass pipeline is used as a heat source for secondary heat exchange of the feed gas. The downstream end of the first bypass pipeline and the heat exchange pipeline are used to perform primary heat exchange on the feed gas. The heat utilization pipeline is equipped with a heat recovery unit.

2. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 1, characterized in that, The primary heat exchanger is a feed preheater installed on the feed pipeline. The feed gas serves as the cold source for the feed preheater, and the first bypass pipeline and the heat utilization pipeline converge to serve as the heat source for the feed preheater.

3. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 2, characterized in that, The secondary heat exchanger is a high-efficiency heat exchanger installed at the rear end of the feed preheater. The feed gas serves as the cold source for the feed preheater, and the high-temperature synthesis gas in the first bypass pipeline serves as the heat source.

4. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 3, characterized in that, The diversion control unit is a three-way regulating valve.

5. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 3, characterized in that, The diversion control unit is equipped with control valves on two parallel branch lines, and the control valves on the two parallel branch lines independently regulate the flow rate of the corresponding branch line.

6. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 3, characterized in that, The high-efficiency heat exchanger, heat recovery unit, and ammonia synthesis tower are integrated into one device, which is a heat pipe reactor or a self-heating reactor.

7. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 4, characterized in that, The feed pipe is provided with a second bypass pipe, which is connected in parallel with the feed preheater and the high-efficiency heat exchanger as a bypass. The second bypass pipe is provided with a temperature control valve.

8. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 7, characterized in that, A temperature control sensor is installed at the top inlet of the ammonia synthesis tower to measure the temperature of the inlet gas. The temperature control sensor is electrically connected to the temperature regulating valve to form a control loop that controls the valve opening by temperature parameters.

9. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 8, characterized in that, A flow sensor is installed on the feed pipe. The flow sensor, temperature control sensor and three-way regulating valve are electrically connected to form a control loop that controls the opening of the three-way regulating valve with the total inlet flow rate as the first parameter and the inlet gas temperature of the synthesis tower as the second parameter.

10. The intelligent flexible control system for recovering heat from green ammonia synthesis according to claim 4, characterized in that, The discharge pipe is equipped with a temperature transmission sensor for measuring the temperature of high-temperature synthesis gas; a first temperature sensor is installed between the feed preheater and the high-efficiency heat exchanger; a second temperature sensor is installed on the ammonia synthesis tower for measuring the temperature of the catalyst frame; a third temperature sensor is installed downstream of the high-efficiency heat exchanger in the first bypass pipe; and a fourth temperature sensor is installed on the junction pipe of the first bypass pipe and the heat utilization pipe.

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