A gas mixing and heating integrated device and system for urea hydrolysis to produce ammonia

Abstract

The application relates to a gas mixing and heating integrated device and system for urea hydrolysis to prepare ammonia, relates to the field of gas treatment and heat energy exchange, and comprises a front flue, an ammonia injection grid and a heat exchange mixing unit, the ammonia injection grid and the heat exchange mixing unit are arranged along the flow direction of flue gas, the heat exchange mixing unit comprises an inlet header, a plurality of heat exchange devices and an outlet header arranged in sequence, the ammonia injection grid and the heat exchange devices are located in the front flue, the inlet header and the outlet header are both located outside the front flue and respectively communicate with two ends of the heat exchange devices, an ammonia-air mixer is arranged between the outlet header and the ammonia injection grid, a dilution fan is connected to one end of the inlet header away from the heat exchange devices, and the ammonia injection grid is used for spraying the mixed gas of ammonia and air generated by the ammonia-air mixer into the front flue and mixing with the flue gas. The application has the effects of realizing low energy consumption, low resistance and safe and stable operation of the device.

Description

Technical Field

[0001] The present application relates to the field of gas processing and heat energy exchange, and in particular to a gas mixing and heating integrated device and system for producing ammonia by urea hydrolysis. Background Art

[0002] SCR (Selective Catalytic Reduction) is the primary denitrification method used in power plant boilers and other applications in my country. Its core principle is to react nitrogen oxides in flue gas with a reducing agent under the action of a catalyst to produce harmless nitrogen and water. In the SCR denitrification process, the hydrolyzed gas (a mixture containing ammonia) generated by the hydrolysis of urea must be mixed with dilution air to form a stable and safe low-concentration ammonia mixture. This mixture is then injected into the flue through an ammonia injection grid to achieve mixing of the hydrolyzed gas and flue gas. To prevent crystallization of the hydrolyzed gas in the mixture, the dilution air must be heated to maintain a temperature of 150-200°C.

[0003] Dilution air heating primarily utilizes steam heat exchangers, electric heaters, or flue gas heat exchangers with standard cross-sections placed in the post-SCR flue. Regarding ammonia injection systems, traditional ammonia injection grids (AIGs) employ a simple mixing method to achieve ammonia-flue gas mixing. Furthermore, traditional denitrification systems utilize separate heat exchangers and mixing devices, each operating independently and forming a traditional denitrification treatment system.

[0004] Regarding the aforementioned related technologies, electric heaters require high power and consume a lot of steam. Due to the difficulty in ensuring steam quality in the steam heat exchanger and the excessive power of the electric heater, the dilution air often underheats. Regarding mixing efficiency, traditional ammonia injection systems use a simple mixing method that cannot adapt to the complex and changing flue gas flow field. This results in uneven mixing of ammonia and dilution air, causing ammonia slip rates within the SCR reactor to exceed the specified limit. Furthermore, traditional denitrification systems utilize separate heat exchangers and mixing devices, resulting in a large number of devices. These devices are severely eroded by flue gas in high-dust environments, increasing safety risks for the unit. Furthermore, due to space constraints when installing multiple devices, heat exchangers are often located in the SCR reactor outlet flue. This often results in excessive ammonia injection, leading to excessive ammonia slip concentrations. Under the catalytic action of the reactor, a side reaction produces ammonium bisulfate, which can easily cause blockage of the heat exchanger and even blockage and corrosion of the air preheater, increasing unit resistance and impacting safe and stable operation. Summary of the Invention

[0005] In order to achieve low energy consumption, low resistance and safe and stable operation of the device, the present application provides a gas mixing and heating integrated device and system for producing ammonia by urea hydrolysis.

[0006] In a first aspect, the present application provides a gas mixing and heating integrated device for producing ammonia by urea hydrolysis, which adopts the following technical solution:

[0007] A gas mixing and heating integrated device for producing ammonia by hydrolysis of urea, comprising a front flue, an ammonia injection grid and a heat exchange mixing unit, wherein the ammonia injection grid and the heat exchange mixing unit are arranged along the flue gas flow direction, and the heat exchange mixing unit comprises an inlet header, a plurality of heat exchange devices and an outlet header arranged in sequence, the ammonia injection grid and the heat exchange device are located inside the front flue, the inlet header and the outlet header are located outside the front flue, and are respectively connected to the two ends of the heat exchange device, an ammonia-air mixer is provided between the outlet header and the ammonia injection grid, and a dilution fan is connected to the end of the inlet header away from the heat exchange device, and the ammonia injection grid is used to inject the mixed gas of ammonia and air generated by the ammonia-air mixer into the front flue and mix it with the flue gas.

[0008] By adopting this technical solution, the ammonia injection grid and heat exchanger are placed inside the front flue, allowing the flue gas to heat the heat exchanger, reducing energy consumption. The inlet and outlet headers are externally connected to the heat exchanger, allowing the device to effectively utilize the space within the flue and making the structure more compact. An ammonia-air mixer is installed between the outlet header and the ammonia injection grid to fully mix ammonia and air. The ammonia injection grid then injects the mixed gas into the front flue to mix with the flue gas, ensuring sufficient contact and mixing between the ammonia and flue gas, which helps improve the reaction efficiency of ammonia and nitrogen oxides in the subsequent denitrification reaction. The inlet header is connected to the dilution fan, which can deliver dilution air to the system and cooperate with the overall operation of the device. On the one hand, it provides sufficient air for the mixing process, and on the other hand, it prevents the crystallization of hydrolyzed gas in the mixed gas, ensuring that the mixed gas is in the appropriate temperature range (150-200℃). It can also realize the combined functions of dilution air heating and ammonia mixing, and systematically solve the problems of traditional denitrification equipment such as high heating energy consumption, heat exchanger blockage, short wear life, uncontrollable or low adjustment accuracy of the dilution air heating system, poor ammonia mixing effect and excessive ammonia escape concentration, ultimately achieving the goal of low energy consumption, low resistance, safe and stable operation of the unit.

[0009] Optionally, the heat exchange device includes an inlet distribution box, several heating elements, several wear-resistant dummy pipes and an outlet distribution box, the inlet distribution box and the outlet distribution box are respectively connected to the two ends of the heating elements, the wear-resistant dummy pipes are located on the side of the heating element close to the ammonia injection grid and the two ends of the wear-resistant dummy pipes are respectively fixedly connected to the inlet distribution box and the outlet distribution box, the wear-resistant dummy pipes are arranged one-to-one corresponding to a row of heating elements close to the ammonia injection grid, and several wear-resistant parts are detachably connected between the inlet distribution box and the outlet distribution box, and the wear-resistant parts are located between the wear-resistant dummy pipes and the ammonia injection grid.

[0010] By adopting this technical solution, the inlet and outlet distribution boxes are connected to the heating element, allowing the dilution air to flow through the heating element and be heated, thus achieving the dilution air heating function. Wear-resistant dummy pipes and wear-resistant parts are installed on the side of the heating element near the ammonia injection grid to prevent excessive flue gas erosion of the heating element, protecting the heating element, reducing wear on the heat exchange device, and extending the service life of the device. Furthermore, the wear-resistant parts are detachable and connectable, facilitating maintenance and replacement, reducing maintenance costs.

[0011] The cam is fixedly provided with a toothed plate on the outside of the cam and is fixedly provided with a toothed plate on the outside of the cam and is fixedly provided with a toothed plate on the inside of the cam and is fixedly provided with a toothed plate on the outside of the cam and is fixedly provided with a toothed plate on the inside of the cam and is fixedly provided with a toothed plate on the inside of the cam and

[0012] By adopting the technical scheme, the wear-resistant false pipe is arranged inside the wear-resistant part at the heating element of the integrated device, which can protect the heating element to some extent and reduce direct abrasion of flue gas on the heating element in a high-dust environment. The plurality of backflow blades are uniformly arranged outside the wear-resistant part along the axial direction of the heating element, and the backflow blades are rotationally connected to the wear-resistant part through the blade adjustable shaft. The rotatable design can flexibly adjust the angle of the backflow blades according to the actual flue gas flow field. The plurality of backflow blades are rotationally connected through the connecting rod, so that the angle adjustment of the plurality of backflow blades can be synchronously performed, and the flue gas flow field can be conveniently controlled and optimized. The gear is meshingly connected with the rack, and the gear is coaxially fixedly connected with the blade adjustable shaft, so that when the push plate is driven to slide by the electric cylinder, the rack can be driven to move, and the gear is driven to rotate, thereby the rotation of the blade adjustable shaft is realized, and the angle of the backflow blade is changed. The sliding part is arranged inside the wear-resistant part and fixedly connected with the rack, and the sliding rod is fixedly arranged on the sliding part, the sliding rod passes through the sliding groove formed in the wear-resistant part and is threadedly connected with the locking nut. When the backflow blade is adjusted to the appropriate angle, the locking nut is tightened, and the position of the backflow blade is locked due to the blocking piece, so that the angle of the backflow blade is stable in the subsequent operation process. The electric cylinder is installed on the outer wall of the front flue, and the sliding of the push plate in the slot is controlled to control the action of the whole mechanism, so that the remote operation and accurate control are facilitated. The structure design can realize the fine adjustment of the flue gas flow field, so that the integrated device can achieve the best heat exchange and mixing effect, the flue gas flow field is optimized, the equipment wear is reduced, the service life of the equipment is prolonged, the overall performance and operation stability of the device are improved, and the problems such as high heating energy consumption, clogging of the heat exchanger, short service life, inability to control or low adjustment precision of the dilution air heating system, poor ammonia mixing effect and excessive ammonia escape concentration are systematically solved, and the purpose of low energy consumption, low resistance and safe and stable operation of the unit is achieved.

[0013] Optionally, the outer side of the wear-resistant part and the surface of the backflow blade are provided with a ceramic wear-resistant layer.

[0014] By adopting the technical scheme, the wear-resistant performance of the wear-resistant part and the backflow blade is improved, the damage caused by flue gas abrasion is reduced, the anti-abrasion capability of the equipment in the flue gas in a high-dust environment is further enhanced, the hidden danger of safe operation of the unit is reduced, and the service life of the equipment is prolonged.

[0015] Optionally, the heat exchange and mixing unit further comprises a bypass pipeline, one end of the bypass pipeline is located between the dilution air fan and the heat exchange and mixing unit, and the other end of the bypass pipeline is located between the heat exchange and mixing unit and the ammonia-air mixer.

[0016] By adopting the above technical solution, part of the gas blown out by the dilution fan can be bypassed by the heat exchange device, and this part of the gas can be used to cool the hot gas coming out of the heat exchange device. For example, when gas of a specific temperature is required and the heating temperature of the heat exchange device is too high, the bypass gas can cool it to the appropriate temperature, thereby more accurately controlling the temperature of the gas entering the ammonia-air mixer.

[0017] Optionally, it also includes a regulating unit, which includes a dilution fan inlet regulating valve, a dilution air heating bypass regulating valve and several dilution air heating branch regulating valves. The dilution fan inlet regulating valve is installed on the side of the dilution fan air inlet, and the several dilution air heating branch regulating valves are respectively installed between the inlet manifold and several heat exchange devices. The dilution air heating bypass regulating valve is installed on the bypass pipe.

[0018] By adopting the above technical solution, the regulating unit can monitor the hydrolysis gas flow, inlet flue gas flow / temperature, dilution air flow, dilution air temperature, etc. in real time based on the data obtained by the detection unit, and control the main regulating valve, heating branch regulating valve and heating bypass regulating valve, so as to adjust the system in real time with high precision under different load conditions and different flue gas parameters, realize the purpose of precise regulation of dilution air heating, and achieve the best energy saving and reliable operation.

[0019] Optionally, a detection unit is also included, which includes a fan outlet cold air pressure transmitter, a fan outlet cold air flow meter, a hot dilution air temperature transmitter, a hot dilution air pressure transmitter, an SCR reactor inlet flue flow meter, and an SCR reactor inlet flue temperature transmitter. The fan outlet cold air pressure transmitter and the fan outlet cold air flow meter are installed between the dilution fan and the bypass duct, the hot dilution air temperature transmitter and the hot dilution air pressure transmitter are installed between the bypass duct and the ammonia-air mixer, and the SCR reactor inlet flue flow meter and the SCR reactor inlet flue temperature transmitter are installed on the front flue.

[0020] By adopting the above technical solution, the cold air pressure and flow data between the dilution fan and the bypass duct, the hot dilution air temperature and pressure data between the bypass duct and the ammonia-air mixer, and the flue gas flow and temperature data at the front flue can be obtained, so as to realize the control of hydrolysis gas flow-inlet flue gas flow / temperature-dilution air flow-dilution air temperature-main regulating valve-heating branch regulating valve-heating bypass regulating valve in combination with the regulating unit, and perform real-time high-precision regulation of the system under different loads and flue gas parameters to achieve the best energy saving and reliable operation.

[0021] Optionally, a plurality of ammonia injection branch valves are installed between the ammonia injection grid and the ammonia-air mixer.

[0022] By adopting the above technical solution, several ammonia injection branch valves are installed between the ammonia injection grid and the ammonia-air mixer, enabling detailed regulation and control of the delivery of the ammonia-air mixture generated by the ammonia-air mixer to the ammonia injection grid. The opening of each ammonia injection branch valve can be precisely adjusted based on actual operating conditions, such as flue gas flow rate, temperature, and nitrogen oxide content, thereby achieving precise control of the flow rate and distribution of the mixed gas injected into the front flue. This further improves the mixing uniformity of ammonia and flue gas, enhances denitrification efficiency, and reduces ammonia escape rate.

[0023] In a second aspect, the present application provides a system for producing ammonia by urea hydrolysis, comprising a urea hydrolysis ammonia production device, a static mixing and heating device, an SCR reactor, and a post-flue duct. The static mixing and heating device is an integrated gas mixing and heating device for producing ammonia by urea hydrolysis as described in any one of the first aspects. The urea hydrolysis ammonia production device and the ammonia-air mixer are connected through a hydrolysis gas pipeline. A hydrolysis gas flowmeter is installed on the hydrolysis gas pipeline. The SCR reactor comprises two catalyst layers and a reserved catalyst layer arranged in sequence along the flue gas flow direction.

[0024] Optionally, the layout and heat exchange effect of the heat exchange device can be simulated and optimized through CFD simulation. Based on the flow field conditions, the heat exchange mixing units can be unevenly arranged across the entire cross-section of the front flue. A target value of 180°C is set for heating after heat exchange. The target air volume required for dilution to a 5% ammonia concentration is obtained based on the hydrolysis gas consumption value provided by the unit. Coordinated control of the dilution air control valve can be achieved through a two-stage neural network algorithm model:

[0025] In the first stage, the flue gas flow rate at the denitrification inlet is predicted based on the multilayer perceptron regression model. The input variables include: unit load, coal consumption, air volume, and denitrification inlet flue gas temperature. The output is the predicted flue gas flow rate.

[0026] In the second stage, based on a multi-output neural network model, the input includes the predicted flue gas flow rate output from the first stage, as well as the dilution air volume target value, the dilution air heating target temperature, the measured flue gas flow rate and flue gas temperature. The output is the opening values ​​of the dilution fan inlet regulating valve, the three dilution air heating branch regulating valves, and the dilution air heating bypass regulating valve. Among them, an 80% weight constraint is imposed on the opening of the dilution fan inlet regulating valve, the total opening weight of the three dilution air heating branch regulating valves is 10%, and the opening weight of the dilution air heating bypass regulating valve is 10%.

[0027] Through this algorithm model, the openings of the dilution fan inlet regulating valve, the dilution air heating branch regulating valve, and the dilution air heating bypass regulating valve are adjusted and controlled according to the load and flue gas heat source parameters.

[0028] By adopting the above technical solutions, we can ensure that the system always operates stably, efficiently and safely near the set target.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. Using flue gas waste heat as a heating source solves the problem of high power electric heaters or high steam consumption of steam heaters. While ensuring the heat exchange area, this device achieves a reasonable and uneven arrangement of the entire cross-section of the device's thermal elements. The heat exchange unit effectively disturbs the flow field, achieving an ammonia mixing effect, and secondary optimization of the flue gas flow field distribution effect. Compared with the traditional independent installation of mixed gas and flue gas heat exchangers, it can reduce the operating resistance of the unit.

[0031] 2. Through the detection and adjustment units, the system controls the hydrolysis gas flow rate, inlet flue gas flow rate / temperature, dilution air flow rate, dilution air temperature, main regulating valve, heating branch regulating valve, and heating bypass regulating valve. This system allows for real-time, high-precision adjustments under varying load conditions and flue gas parameters, achieving optimal energy conservation and reliable operation.

[0032] 3. The device has the combined functions of excellent heat exchange effect and optimal ammonia mixing, realizes the layout of the flue gas in front of the SCR reactor, has the ability to optimize the original flue gas flow field, further avoids excessive ammonia escape concentration, and achieves the goals of low resistance, low abrasion, long life, safe and stable operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a schematic diagram of an integrated gas mixing and heating device for producing ammonia by hydrolyzing urea.

[0034] Figure 2 It is a structural diagram of the heat exchange mixing unit.

[0035] Figure 3 yes Figure 2 Schematic diagram of the cross section in the AA direction.

[0036] Figure 4 yes Figure 3 Enlarged schematic diagram of part A.

[0037] Figure 5 It is a partial schematic diagram of the wear-resistant parts and push plates.

[0038] Figure 6 A schematic diagram of a system for producing ammonia by hydrolysis of urea.

[0039] Figure 7 This is a temperature distribution diagram of the heat exchange mixing unit of the static mixing heating device with diluted air heating and ammonia injection optimization according to the present invention, which is simulated by CFD digital simulation.

[0040] Figure 8This is a CFD digital simulation of the NH3 concentration distribution diagram before and after the mixing of ammonia and flue gas in the static mixing heating device with diluted air heating and optimized ammonia injection of the present invention.

[0041] Figure 9 This is a CFD digital simulation of the velocity concentration distribution diagram of ammonia and flue gas before and after mixing in the static mixing heating device with diluted air heating and optimized ammonia injection of the present invention.

[0042] Figure 10 It is a flowchart of the steps of the neural network algorithm.

[0043] Figure 11 yes Figure 10 The network structure diagram of the neural network model in .

[0044] Explanation of reference numerals: 100, urea hydrolysis ammonia production device; 110, hydrolysis gas flowmeter; 200, static mixing and heating device; 300, SCR reactor; 310, catalyst layer; 320, reserved catalyst layer; 400, rear flue; 1, front flue; 11, electric cylinder; 12, push plate; 121, slot; 2, ammonia injection grid; 21, ammonia injection branch valve; 3, heat exchange mixing unit; 31, inlet header; 32, heat exchange device; 321, inlet distribution box; 322, heating element; 323, outlet distribution box; 33, wear-resistant false pipe; 34, outlet header; 35, wear-resistant parts; 351, backflow blade; 352, blade adjustable shaft; 353, connecting Rod; 354, gear; 355, rack; 356, sliding part; 3561, sliding rod; 357, slide groove; 358, locking nut; 359, baffle; 36, bypass pipe; 4, regulating unit; 41, dilution fan inlet regulating valve; 42, dilution air heating bypass regulating valve; 43, dilution air heating branch regulating valve; 5, detection unit; 51, fan outlet cold air pressure transmitter; 52, fan outlet cold air flow meter; 53, hot dilution air temperature transmitter; 54, hot dilution air pressure transmitter; 55, SCR reactor inlet flue flow meter; 56, SCR reactor inlet flue temperature transmitter; 6, ammonia-air mixer; 7, dilution fan. DETAILED DESCRIPTION

[0045] The present application is further described in detail below in conjunction with all the accompanying drawings.

[0046] In a first aspect, embodiments of the present application disclose an integrated gas mixing and heating device for producing ammonia by hydrolyzing urea.

[0047] Reference Figure 1A gas mixing and heating integrated device for producing ammonia by urea hydrolysis includes a front flue 1, an ammonia injection grid 2 and a heat exchange mixing unit 3. The ammonia injection grid 2 and the heat exchange mixing unit 3 are arranged along the flue gas flow direction. The ammonia injection grid 2 is located inside the front flue 1. The two ends of the heat exchange mixing unit 3 are respectively connected to a dilution fan 7 and an ammonia-air mixer 6.

[0048] Reference Figure 1 The dilution fan 7 can transport air to the heat exchange mixing unit 3 for heating. The ammonia-air mixer 6 can fully mix the ammonia produced by hydrolysis with the heated air, and then inject the mixed gas into the front flue 1 through the ammonia injection grid 2 to mix with the flue gas. The air in the heat exchange mixing unit 3 is then heated. This ensures that the ammonia is fully diluted to form a stable and safe low-concentration ammonia mixture, and can also use the waste heat of the flue gas to heat the dilution air, reducing heating energy consumption. At the same time, it optimizes the mixing effect of ammonia and flue gas, helping to improve denitrification efficiency and reduce ammonia escape rate. Because the device has both heat exchange and ammonia-air mixing functions, the number of equipment in the flue in a high-dust environment is reduced, the failure rate is reduced, and the equipment occupies a small space, achieving the purpose of arranging the equipment in the SCR inlet flue before the SCR reactor 300, thereby avoiding the problem of ammonium bisulfate crystallization blockage and corrosion caused by placing the flue gas heat exchanger in the outlet flue after the SCR reactor 300, thereby achieving the goal of reducing the flue gas resistance of the unit operation and extending the service life of the equipment. The flue gas waste heat is used as the heating source, fully considering the worst working conditions, ensuring the heat exchange area, ensuring the dilution air heating effect, and solving the problems of high dilution air heating energy consumption and insufficient temperature rise.

[0049] Reference Figure 2The heat exchange mixing unit 3 includes an inlet header 31, several heat exchange devices 32 and an outlet header 34 arranged in sequence. The heat exchange device 32 is located inside the front flue 1, and the inlet header 31 and the outlet header 34 are both located outside the front flue 1, and are respectively connected to the two ends of the heat exchange device 32. The ammonia-air mixer 6 is installed between the outlet header 34 and the ammonia injection grid 2. The end of the inlet header 31 away from the heat exchange device 32 is connected to the dilution fan 7. The inlet header 31 and the outlet header 34 are connected to the heat exchange device 32 on the outside, which allows the device to effectively utilize the space in the flue and make the structure more compact. The ammonia-air mixer 6 is set between the outlet header 34 and the ammonia injection grid 2, which can fully mix ammonia and air. The ammonia injection grid 2 then injects the mixed gas into the front flue 1 to mix with the flue gas, ensuring that the ammonia and flue gas can fully contact and mix, which helps to improve the reaction efficiency of ammonia and nitrogen oxides in the subsequent denitrification reaction. The inlet header 31 is connected to the dilution fan 7, which can deliver dilution air to the system and cooperate with the overall operation of the device. On the one hand, it provides sufficient air for the mixing process, and on the other hand, it prevents the crystallization of hydrolyzed gas in the mixed gas, ensuring that the mixed gas is in the appropriate temperature range (150-200℃). It can also realize the combined functions of dilution air heating and ammonia mixing, and systematically solve the problems of high heating energy consumption, heat exchanger blockage, short wear life, uncontrollable or low adjustment accuracy of the dilution air heating system, poor ammonia mixing effect and excessive ammonia escape concentration in traditional denitrification equipment, and ultimately achieve the purpose of low energy consumption, low resistance, safe and stable operation of the unit.

[0050] Reference Figure 2 and Figure 3 The heat exchange device 32 includes an inlet distribution box 321, several heating elements 322, several wear-resistant dummy pipes 33, and an outlet distribution box 323. The inlet distribution box 321 and the outlet distribution box 323 are respectively connected to the ends of the heating elements 322. The wear-resistant dummy pipes 33 are located on the side of the heating elements 322 near the ammonia injection grid 2, and the ends of the wear-resistant dummy pipes 33 are respectively fixedly connected to the inlet distribution box 321 and the outlet distribution box 323. The wear-resistant dummy pipes 33 are arranged one-to-one with a row of heating elements 322 near the ammonia injection grid 2. The heating elements 322 can be heat pipes, which have efficient heat transfer performance and can quickly transfer heat to the dilution air.

[0051] Reference Figure 3 and Figure 4, a number of wear-resistant parts 35 are detachably connected between the inlet distribution box 321 and the outlet distribution box 323. The detachable connection of the wear-resistant parts 35 facilitates maintenance and replacement, thereby reducing maintenance costs. The wear-resistant parts 35 are located between the wear-resistant dummy pipe 33 and the ammonia injection grid 2, and the wear-resistant dummy pipe 33 is located on the inner side of the wear-resistant parts 35. The provision of the wear-resistant dummy pipe 33 and the wear-resistant parts 35 can prevent the excessive flushing of the heating element 322 by the flue gas, protect the heating element 322, reduce the wear of the heat exchange device 32, and extend the service life of the device. The outer side of the wear-resistant parts 35 are evenly provided with a number of reverse flow blades 351 along the axial direction of the heating element 322, and the reverse flow blades 351 are fixedly connected to the blade adjustable shaft 352, which is rotatably connected to the wear-resistant parts 35 along its own axis. The heat exchange device 32 is divided into at least three groups, which are detachable modularly assembled. Each group can operate independently and flexibly, and can be repaired and replaced modularly during maintenance. Its module layout adopts a full-cross-section non-uniform layout. The number of heating elements 322 in each heat exchange device 32 can be different, and modules with more dense heat exchange elements are arranged in places with high flue gas flow rates. The wear-resistant parts 35 on the windward side can be replaced independently. At the same time, the backflow blades 351 installed on the wear-resistant parts 35 can be adjusted in angle by rotating the blade adjustable shaft 352 to achieve the best mixing flow field, optimize the flue gas flow field, improve the mixing uniformity of ammonia and flue gas, and thus improve the denitrification efficiency and reduce the ammonia escape rate. The wear-resistant parts 35 can be wear-resistant angle irons. Wear-resistant angle irons usually have high strength and hardness, can better resist the erosion and wear of dust in the flue gas, and provide reliable protection for the heating elements 322. Their unique angular structure is easy to position and fix during installation, and can be firmly installed in the designated position to ensure that they will not loosen or shift during long-term use. In addition, the manufacturing process of wear-resistant angle irons is relatively mature and low-cost. While ensuring the protective effect, it can effectively reduce the manufacturing cost of the equipment.

[0052] Reference Figure 4 and Figure 5The ends of the reverse flow blades 351, which are spaced away from the wear-resistant member 35, are rotatably connected to a common connecting rod 353. The end of the blade adjustable shaft 352 of one of the reverse flow blades 351 arranged along the axis of the heating element 322, which is spaced away from the reverse flow blade 351, passes through the wear-resistant member 35 and is coaxially fixedly connected to a gear 354. The gear 354 is meshed with a rack 355. A slider 356 is slidably connected to the inner side of the wear-resistant member 35, and the slider 356 is fixedly connected to the rack 355. When the wear-resistant angle iron is used as the wear-resistant member 35, the reverse flow blades 351 are provided on both sides of the wear-resistant angle iron, and each side is provided with a set of gears 354 and racks 355. The two racks 355 are fixed to the ends of the slider 356. By pushing the sliding member 356, the two racks 355 are driven to slide, and then the two gears 354 are driven to rotate respectively, driving the corresponding backflow blades 351 to rotate, and the connecting rod 353 is used to connect the backflow blades 351 to rotate together, so that the angle adjustment of multiple backflow blades 351 in the same row can be carried out synchronously, which is convenient for unified control and optimization of the flue gas flow field.

[0053] Reference Figure 4 and Figure 5 A sliding rod 3561 is fixedly provided on the side of the sliding member 356 close to the wear-resistant member 35, and a sliding groove 357 is provided on the wear-resistant member 35 for the sliding rod 3561 to slide. The end of the sliding rod 3561 away from the sliding member 356 passes through the sliding groove 357 and is threadedly connected to a locking nut 358. A blocking piece 359 coaxially fixedly connected to the sliding rod 3561 is provided between the locking nut 358 and the wear-resistant member 35, and a push plate 12 is provided between the blocking piece 359 and the locking nut 358. An electric cylinder 11 for pushing the push plate 12 to slide is fixedly provided on the outer wall of the front flue 1, and the push plate 12 is provided with a slot 121 for the sliding of the sliding rod 3561. During installation, the push plate 12 is fastened to the baffle 359 by inserting the slide rod 3561 into the slot 121 and turning the lock nut 358. This simultaneously aligns the slide 356 with the wear-resistant member 35. The slide 356 is positioned according to the length of the chute 357 so that it always covers the chute 357, preventing smoke from passing through it. When the heat exchange devices 32 are arranged unevenly across their entire cross-section, the number of heating elements 322 in each heat exchange device 32 varies, and the position of the slide rod 3561 changes accordingly. The slot 121 is opened along the arrangement direction of the heat exchange and mixing units 3 to accommodate the positions of the heating elements 322 and the slide rod 3561. The cooperation between the slide rod 3561 and the slide groove 357 enables the electric cylinder 11 to push the push plate 12 to slide, thereby driving the slide rod 3561 and the sliding member 356 to slide, and then driving the rack 355 to move, driving the gear 354 to rotate, and realizing the rotation of the blade adjustable shaft 352, thereby changing the angle of the backflow blade 351.

[0054] The outer side of the wear-resistant part 35 and the surface of the reverse flow blade 351 are both provided with a ceramic wear-resistant layer, which improves the wear resistance of the wear-resistant part 35 and the reverse flow blade 351, reduces the damage caused by flue gas abrasion, further enhances the equipment's anti-abrasion ability in high-dust flue gas environments, reduces hidden dangers in the safe operation of the unit, and extends the service life of the equipment.

[0055] Reference Figure 1 The heat exchange and mixing unit 3 also includes a bypass pipe 36. One end of the bypass pipe 36 is located between the dilution fan 7 and the heat exchange and mixing unit 3, and the other end of the bypass pipe 36 is located between the heat exchange and mixing unit 3 and the ammonia-air mixer 6. Part of the gas blown out by the dilution fan 7 enters the heat exchange device 32, while the other part does not pass through the heat exchange device 32. The gas that does not pass through the heat exchange device 32 is used to cool the hot gas leaving the heat exchange device 32. For example, if the mixed air temperature needs to be maintained at 150-200°C, if the gas is too hot after being heated by the heat exchange device 32, the bypass gas can cool it to the appropriate temperature, thereby more accurately controlling the temperature of the gas entering the ammonia-air mixer 6.

[0056] Reference Figure 1 This embodiment also includes a control unit 4 and a detection unit 5. Through the detection and control unit 4, the system can be adjusted in real time with high precision under different load conditions and flue gas parameters, achieving optimal energy savings and reliable operation. Compared to traditional control methods, energy savings are expected to be 20%.

[0057] Reference Figure 1 The regulating unit 4 includes a dilution fan inlet regulating valve 41, a dilution air heating bypass regulating valve 42, and several dilution air heating branch regulating valves 43. The dilution fan inlet regulating valve 41 is installed on the air inlet side of the dilution fan 7 to control the total amount of air entering the dilution fan 7. Several dilution air heating branch regulating valves 43 are installed between the inlet manifold 31 and several heat exchangers 32 to control the air intake of each heat exchanger 32. The dilution air heating bypass regulating valve 42 is installed on the bypass duct 36 to control the opening and closing of the bypass duct 36 and the flow rate of the dilution air.

[0058] Reference Figure 1The detection unit 5 includes a fan outlet cold air pressure transmitter 51, a fan outlet cold air flow meter 52, a hot dilution air temperature transmitter 53, a hot dilution air pressure transmitter 54, an SCR reactor inlet flue flow meter 55, and an SCR reactor inlet flue temperature transmitter 56. The fan outlet cold air pressure transmitter 51 and the fan outlet cold air flow meter 52 are both installed between the dilution fan 7 and the bypass duct 36, the hot dilution air temperature transmitter 53 and the hot dilution air pressure transmitter 54 are both installed between the bypass duct 36 and the ammonia-air mixer 6, and the SCR reactor inlet flue flow meter 55 and the SCR reactor inlet flue temperature transmitter 56 are both installed on the front flue 1.

[0059] Reference Figure 1 Several ammonia injection branch valves 21 are installed between the ammonia injection grid 2 and the ammonia-air mixer 6. These valves finely regulate and control the delivery of the ammonia-air mixture generated by the ammonia-air mixer 6 to the ammonia injection grid 2. The opening of each ammonia injection branch valve 21 can be precisely adjusted based on actual operating conditions, such as flue gas flow rate, temperature, and nitrogen oxide content, thereby achieving precise control over the flow rate and distribution of the mixed gas injected into the front flue 1. This further improves the mixing uniformity of ammonia and flue gas, enhances denitrification efficiency, and reduces ammonia escape rate.

[0060] The implementation principle of the gas mixing and heating integrated device for urea hydrolysis to produce ammonia in the embodiment of the present application is: using flue gas waste heat as a heating source to solve the problem of high power of electric heaters (such as a 600MW unit requires more than 500kW) or high steam consumption of steam heaters (up to 0.5 to 1.0 t / h). With 8,000 hours of operation per year, based on an electricity fee of 0.5 yuan / h and a steam fee of 100 yuan / h, a single unit can save 2 million yuan a year compared with electric heaters and about 800,000 yuan compared with steam heaters. While ensuring adequate heat exchange area, this device achieves a rationally uneven arrangement of the thermal elements across their entire cross-section. The heat exchange unit effectively perturbs the flow field, enhancing ammonia mixing and re-optimizing the flue gas flow distribution. Compared to traditional, independent mixed gas and flue gas heat exchangers, this reduces flue gas resistance by 100 Pa. For a 600 MW unit with a flue gas volume of 1.8 million Nm³ / h, this saves 100 kW / h of induced draft fan electricity costs per hour. With 8,000 hours of operation per year, a single unit can achieve an annual savings of 400,000 yuan. Detection and adjustment unit 4 controls the hydrolysis gas flow rate, inlet flue gas flow / temperature, dilution air flow, dilution air temperature, main control valve, heating branch control valve, and heating bypass control valve. This allows for real-time, high-precision system adjustment under varying load conditions and flue gas parameters, achieving optimal energy savings and reliable operation. Compared to traditional control methods, this is expected to result in 20% energy savings. The device has the combined functions of excellent heat exchange effect and optimal ammonia mixing, realizes the layout of the inlet flue in front of the SCR reactor, has the ability to optimize the original flue gas flow field, further avoids excessive ammonia escape concentration, and achieves the goals of low resistance, low abrasion, long life, safe and stable operation of the unit.

[0061] Reference Figure 6 On the other hand, an embodiment of the present application discloses a system for producing ammonia by urea hydrolysis, comprising a urea hydrolysis ammonia production device 100, a static mixing and heating device 200, an SCR reactor 300, and a rear flue 400, wherein the static mixing and heating device 200 is the above-mentioned gas mixing and heating integrated device for producing ammonia by urea hydrolysis, the urea hydrolysis ammonia production device 100 is connected to the ammonia-air mixer 6 through a hydrolysis gas pipeline, a hydrolysis gas flowmeter 110 is installed on the hydrolysis gas pipeline, and the SCR reactor 300 includes two catalyst layers 310 and a reserved catalyst layer 320 arranged in sequence along the flue gas flow direction.

[0062] Reference Figure 6 The urea hydrolysis ammonia production unit 100 hydrolyzes urea solution to produce a mixed gas containing ammonia. A hydrolyzed gas pipeline transports the hydrolyzed gas to the ammonia-air mixer 6, where it is mixed with heated and conditioned dilution air. A hydrolyzed gas flowmeter 110 measures the hydrolyzed gas flow rate to precisely control the amount of ammonia added.

[0063] Reference Figure 6The two catalyst layers 310 of the SCR reactor 300 catalyze the reduction of ammonia and nitrogen oxides in the flue gas, converting them into harmless nitrogen and water. The reserved catalyst layer 320 provides space for future upgrades or efficiency improvements. When environmental protection requirements are further strengthened, the catalyst layer 310 can be easily added to improve denitration efficiency.

[0064] Reference Figure 6 The rear flue 400 is used to discharge the flue gas after denitrification treatment. Its structure and material need to be reasonably designed according to the composition and temperature of the flue gas to ensure long-term stable operation.

[0065] Reference Figure 7 、 Figure 8 and Figure 9 The method for selecting the specifications of the heat exchange device 32 is as follows: the heat exchange and mixing units 3 are unevenly arranged in the entire cross-section of the front flue 1, that is, the number of heating elements 322 connected to each heat exchange device 32 is different. Through CFD simulation, the arrangement and heat exchange effect of the heating elements 322 are simulated and optimized to obtain the temperature distribution diagram of the heat exchange and mixing unit 3, the NH3 concentration distribution comparison diagram before and after the mixing of ammonia and flue gas, and the velocity concentration distribution comparison diagram before and after the mixing of ammonia and flue gas. According to the simulation results, the number of heating elements 322 of each heat exchange device 32 is replaced until the best heat exchange and mixing effect is achieved according to the flow field conditions in the three figures, and the flue gas flow field is optimized at the same time. Specifically, the heating medium, i.e., the flue gas, can achieve the purpose of heat exchange with the cold air in the heating element 322 in the front flue 1. The temperature deviation of the cold air after heat exchange in each heat exchange element is small, indicating that there is no dead zone in the heat exchange and heating is achieved. After adjustment, due to the uneven arrangement of the heating elements 322 connected to each heat exchange device 32 in the static mixing heating device 200, the unevenly distributed ammonia and the NH3 mixed gas after the flue gas are mixed are blocked when flowing, so that the NH3 mixed gas passing through the static mixing heating device 200 is evenly mixed. By comparing the NH3 concentration and velocity concentration of the two sections before and after the static mixing heating device 200, it is found that its uniformity is better, indicating that the mixing is more uniform.

[0066] Reference Figure 10 and Figure 11, according to the consumption value of the hydrolysis gas of the urea hydrolysis ammonia production device 100, the target value of the air amount required for dilution to 5% ammonia gas concentration is obtained, and the opening of the dilution air fan inlet regulating valve 41, the dilution air heating branch regulating valve 43 and the dilution air heating bypass regulating valve 42 needs to be adjusted to achieve the temperature of the air before entering the ammonia-air mixer 6 after heat exchange in the urea hydrolysis ammonia production system is set to 180°C. The adjustment of the adjustment unit 4 is to adjust and control in time and accurately according to different loads and flue gas heat source parameters through a neural network algorithm. The specific neural network algorithm is: a data set is constructed by collecting running data and personnel using equipment to measure data at measuring points; feature classification and data preprocessing are performed on the data set; the data set is reconstructed and divided into a training set and a validation set; a model is established based on the neural network through the training set and the validation set; the model is deployed on the edge gateway through quality assessment and access of power plant running data; and finally, real-time inference and calculation results are output. The model established based on the neural network is according to the mutual influence among the dilution air amount, the dilution heating temperature and the flue gas flow and temperature, and finally an optimal value is reached in the neural network, and the opening requirements of the dilution air fan inlet regulating valve 41, the dilution air heating branch regulating valve 43 and the dilution air heating bypass regulating valve 42 are generated according to the optimal value.

[0067] Specifically, the two-stage neural network algorithm model is used for timely and accurate adjustment and control.

[0068] First stage, denitration inlet flue gas flow prediction model:

[0069] Algorithm selection:

[0070] A multilayer perceptron (MLP) regression model is selected because it can effectively capture the nonlinear mapping relationship and coupling effect between the input variables such as unit load, coal consumption, air volume and flue gas temperature and the output variable of flue gas flow.

[0071] Model structure:

[0072] Input layer: 4 neurons (corresponding to 4 input variables);

[0073] Hidden layer: double hidden layer structure, 16 neurons in the first hidden layer and 8 neurons in the second hidden layer, both using ReLU activation function;

[0074] Output layer: 1 neuron (predicted flue gas flow , Nm³ / h), using linear activation function.

[0075] Data modeling:

[0076] 1) Input data processing

[0077] Standardize the original data:

[0078]

[0079] Where: is the i-th input variable (load / coal quantity / air volume / smoke temperature), is the mean of the training set, is the standard deviation.

[0080] 2) The hidden layer calculates the output of the neuron in the mth layer of the lth layer:

[0081]

[0082] Where: is the weight matrix, is the bias vector, .

[0083] 3) Output layer calculation

[0084]

[0085] Where: To predict the flue gas flow rate (Nm³ / h), is the output layer weight, is the output layer bias.

[0086] Training methods:

[0087] Loss function: mean square error (MSE);

[0088]

[0089] Optimizer: Adam optimizer;

[0090] Training data: select historical DCS system data;

[0091] Validation method: K-fold cross validation.

[0092] The algorithm steps include:

[0093] Data collection: extract load, coal consumption, air volume, denitrification inlet flue gas temperature and corresponding flue gas flow;

[0094] Data cleaning: remove abnormal points (such as zero data during downtime);

[0095] Standardization processing: normalize according to formula (1);

[0096] Model training: Iterate multiple epochs and retain the model with the lowest validation set loss;

[0097] Online application: real-time input of current operating parameters and output of predicted flue gas flow.

[0098] Second stage, dilution air regulating valve coordinated control model

[0099] Algorithm selection:

[0100] A multi-output neural network (Multi-output MLP) is used because it can simultaneously predict five highly correlated control variables (the dilution fan inlet regulating valve 41 plus three dilution air heating branch regulating valves 43 plus the dilution air heating bypass regulating valve 42) and meet the weight constraint requirements.

[0101] Model structure:

[0102] Input layer: 7 neurons, input vector construction

[0103]

[0104] in:

[0105] : Dilution air volume (2500-5000Nm³ / h);

[0106] : Dilution air heating temperature (150-200℃);

[0107] : Flue gas flow rate (1.2×10 6 Nm³ / h);

[0108] : Flue gas temperature (350-380℃);

[0109] Hidden layer: three hidden layer structure, the first hidden layer: 32 neurons, the second hidden layer: 16 neurons, the third hidden layer: 8 neurons, all with LeakyReLU activation;

[0110] Output layer: 5 neurons (corresponding to 5 regulating valves), using Sigmoid activation function (mapping 0% to 100% opening value).

[0111] Output constraint processing:

[0112] Embed weight constraints directly in the output layer computation:

[0113]

[0114] Calculation of the opening degree of the 3 dilution air heating branch regulating valves 43:

[0115]

[0116] Calculation of the opening degree of the dilution air heating bypass regulating valve 42:

[0117]

[0118] Where: h is the hidden layer output vector, W and b are the corresponding weights and biases.

[0119] train:

[0120] Loss function: Weighted MSE

[0121]

[0122] Optimizer: RMSprop;

[0123] Data augmentation: Randomly perturb the input parameters to improve model robustness;

[0124] Transfer learning: Reuse the weights of the first two layers of the first-stage (smoke flow prediction) model as initialization to accelerate convergence and utilize learned features.

[0125] Online control steps:

[0126] 1) Parameter fusion: integrating real-time operation data ( , , , ) and the predicted flue gas flow rate output from the first stage ( );

[0127] 2) Feature screening: Calculate the Pearson correlation coefficient of the input parameters, retain features with an absolute value ≥ 0.3 for the final model input, and remove weakly correlated or redundant features;

[0128] 3) Dynamic normalization: normalize the input vector in real time according to the mean and standard deviation within the current working condition window;

[0129] 4) Forward propagation: The processed input vector is input into the second-stage model and the predicted opening values ​​of the five control valves are calculated according to the above formula;

[0130] 5) Safety verification and output: Make a physical feasibility judgment on the predicted opening value (if any opening value > 100%, it will be limited to 100%; if it < 0%, it will be limited to 0%), and send the final opening instruction to each control valve actuator.

[0131] The implementation principle of this embodiment is as follows: This system organically integrates a urea hydrolysis ammonia production unit 100, a static mixing and heating unit 200, an SCR reactor 300, and a post-flue duct 400 to form a complete denitrification treatment system. The static mixing and heating unit 200 utilizes flue gas waste heat to heat the dilution air, achieving efficient energy utilization while also improving the uniformity of ammonia-flue gas mixing. A two-stage neural network algorithm accurately predicts the critical but difficult-to-measure parameter (flue gas flow rate) and strictly meets the operational weight constraints of valve openings (80% for the main valve, 10% for the branch valves, and 10% for the bypass valve), ensuring stable, efficient, and safe operation near the set targets (180°C hot air, 5% ammonia concentration). The catalyst layer 310 in the SCR reactor 300 ensures the effective removal of nitrogen oxides. The coordinated operation of the entire system overcomes the problems of high heating energy consumption, low mixing efficiency, and severe equipment wear associated with traditional denitrification systems, improving denitrification efficiency and reducing ammonia slip, meeting increasingly stringent environmental protection requirements and ensuring safe and stable operation of the unit.

[0132] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A gas mixing and heating integrated device for producing ammonia by urea hydrolysis, characterized by: The invention comprises a front flue (1), an ammonia spraying grid (2) and a heat exchange mixing unit (3), wherein the ammonia spraying grid (2) and the heat exchange mixing unit (3) are arranged along the flue gas flow direction, wherein the heat exchange mixing unit (3) comprises an inlet header (31), a plurality of heat exchange devices (32) and an outlet header (34) arranged in sequence, wherein the ammonia spraying grid (2) and the heat exchange device (32) are located inside the front flue (1), the inlet header (31) and the outlet header (34) are located outside the front flue (1) and are respectively connected to the two ends of the heat exchange device (32), an ammonia-air mixer (6) is provided between the outlet header (34) and the ammonia spraying grid (2), and a dilution fan (7) is connected to the end of the inlet header (31) away from the heat exchange device (32).The ammonia spraying grid (2) is used to spray the mixed gas of ammonia and air generated by the ammonia-air mixer (6) into the front flue (1) and mix it with the flue gas. The heat exchange device (32) includes an inlet distribution box (321), a plurality of heating elements (322), a plurality of wear-resistant false pipes (33) and an outlet distribution box (323). The inlet distribution box (321) and the outlet distribution box (323) are respectively connected to the two ends of the heating element (322). The wear-resistant false pipe (33) is located on the side of the heating element (322) close to the ammonia spraying grid (2), and the two ends of the wear-resistant false pipe (33) are respectively connected to the inlet distribution box (321) and the outlet distribution box (323). ) is fixedly connected, the wear-resistant false pipe (33) is arranged in a one-to-one correspondence with a row of heating elements (322) near the ammonia spraying grid (2), and a plurality of wear-resistant parts (35) are detachably connected between the inlet distribution box (321) and the outlet distribution box (323). The wear-resistant false pipe (33) is located on the inner side of the wear-resistant part (35), and the outer side of the wear-resistant part (35) is evenly provided with a plurality of guide blades (351) along the axial direction of the heating element (322). The guide blade (351) is fixedly connected to a blade adjustable shaft (352), and the blade adjustable shaft (35 2) It is connected to the wear-resistant part (35) by rotation along its own axis, and one end of several guide blades (351) away from the wear-resistant part (35) is connected to the same connecting rod (353) by common rotation, and one end of the blade adjustable shaft (352) away from the guide blade (351) passes through the wear-resistant part (35) and is fixedly connected to the gear (354) on the same axis. The gear (354) is meshed with the rack (355), and the inner side of the wear-resistant part (35) is fitted with a sliding part (356) for sliding connection. The sliding part (356) is fixedly connected to the rack (355), and a sliding rod (3561) is fixedly provided on the side of the sliding part (356) close to the wear-resistant part (35). The wear part (35) is provided with a slide groove (357) for the slide rod (3561) to slide. One end of the slide rod (3561) away from the slide part (356) passes through the slide groove (357) and is threadedly connected to a locking nut (358). A baffle (359) coaxially fixedly connected to the slide rod (3561) is provided between the locking nut (358) and the wear-resistant part (35). A push plate (12) is provided between the baffle (359) and the locking nut (358). An electric cylinder (11) for pushing the push plate (12) to slide is fixedly provided on the outer wall of the front flue (1). The push plate (12) is provided with a slot (121) for the slide rod (3561) to slide.

2. The gas mixing and heating integrated device for producing ammonia by urea hydrolysis according to claim 1, characterized in that: The outer side of the wear-resistant part (35) and the surface of the guide vane (351) are both provided with a ceramic wear-resistant layer.

3. The gas mixing and heating integrated device for producing ammonia by urea hydrolysis according to claim 1, characterized in that: The heat exchange mixing unit (3) further comprises a bypass pipe (36), one end of the bypass pipe (36) being located between the dilution fan (7) and the heat exchange mixing unit (3), and the other end of the bypass pipe (36) being located between the heat exchange mixing unit (3) and the ammonia-air mixer (6).

4. The gas mixing and heating integrated device for producing ammonia by urea hydrolysis according to claim 3, characterized in that: The system further comprises a regulating unit (4), wherein the regulating unit (4) comprises a dilution fan inlet regulating valve (41), a dilution air heating bypass regulating valve (42), and a plurality of dilution air heating branch regulating valves (43). The dilution fan inlet regulating valve (41) is installed on the air inlet side of the dilution fan (7), the plurality of dilution air heating branch regulating valves (43) are respectively installed between the inlet header (31) and the plurality of heat exchange devices (32), and the dilution air heating bypass regulating valve (42) is installed on the bypass pipe (36).

5. The gas mixing and heating integrated device for producing ammonia by urea hydrolysis according to claim 3, characterized in that: The invention also includes a detection unit (5), wherein the detection unit (5) includes a fan outlet cold air pressure transmitter (51), a fan outlet cold air flow meter (52), a hot dilution air temperature transmitter (53), a hot dilution air pressure transmitter (54), an SCR reactor inlet flue flow meter (55), and an SCR reactor inlet flue temperature transmitter (56). The fan outlet cold air pressure transmitter (51) and the fan outlet cold air flow meter (52) are installed between the dilution fan (7) and the bypass duct (36), the hot dilution air temperature transmitter (53) and the hot dilution air pressure transmitter (54) are installed between the bypass duct (36) and the ammonia-air mixer (6), and the SCR reactor inlet flue flow meter (55) and the SCR reactor inlet flue temperature transmitter (56) are installed on the front flue (1).

6. The gas mixing and heating integrated device for producing ammonia by urea hydrolysis according to claim 1, characterized in that: A plurality of ammonia injection branch valves (21) are installed between the ammonia injection grid (2) and the ammonia-air mixer (6).

7. A system for producing ammonia by hydrolysis of urea, characterized in that: The invention comprises a urea hydrolysis ammonia production device (100), a static mixing and heating device (200), an SCR reactor (300), and a back flue (400). The static mixing and heating device (200) is a gas mixing and heating integrated device for urea hydrolysis ammonia production according to any one of claims 1 to 6. The urea hydrolysis ammonia production device (100) is connected to the ammonia-air mixer (6) through a hydrolysis gas pipeline. A hydrolysis gas flowmeter (110) is installed on the hydrolysis gas pipeline. The SCR reactor (300) comprises two catalyst layers (310) and a reserved catalyst layer (320) arranged in sequence along the flue gas flow direction.

8. The system for producing ammonia by hydrolysis of urea according to claim 7, characterized in that: The arrangement and heat exchange effect of the heat exchange device (32) are simulated and optimized by means of CFD simulation. According to the flow field conditions, the heat exchange mixing unit (3) is unevenly arranged in the entire cross section of the front flue (1). The target value of heating to 180°C after heat exchange is set. The target value of the air volume required for dilution to 5% ammonia concentration is obtained through the consumption value of the hydrolysis gas given by the unit. The coordinated control of the dilution air regulating valve is realized through a two-stage neural network algorithm model: In the first stage, the flue gas flow rate at the denitrification inlet is predicted based on the multilayer perceptron regression model. The input variables include unit load, coal consumption, air volume, and flue gas temperature at the denitrification inlet. The output is the predicted flue gas flow rate. In the second stage, based on the multi-output neural network model, the input includes the predicted flue gas flow output in the first stage, as well as the dilution air volume target value, the dilution air heating target temperature, the measured flue gas flow and flue gas temperature, and the output is the opening value of the dilution fan inlet regulating valve (41), the three dilution air heating branch regulating valves (43) and the dilution air heating bypass regulating valve (42); wherein, an 80% weight constraint is imposed on the opening of the dilution fan inlet regulating valve (41), the total opening weight of the three dilution air heating branch regulating valves (43) is 10%, and the opening weight of the dilution air heating bypass regulating valve (42) is 10%; Through the algorithm model, the openings of the dilution fan inlet regulating valve (41), the dilution air heating branch regulating valve (43), and the dilution air heating bypass regulating valve (42) are adjusted and controlled according to the load and flue gas heat source parameters.

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