Liquid ammonia evaporator for flue gas denitration

Abstract

The invention relates to a liquid ammonia evaporator for flue gas denitration, and belongs to the technical field of liquid ammonia evaporation devices. The evaporator comprises a bracket, a tank body and a heat exchange unit, and aims to solve the problems of non-uniform heat exchange, frequent blockage, poor structural reliability and the like of the traditional liquid ammonia evaporator. The U-shaped pipelines which are concentrically arranged are adopted for heat exchange, the hot water flowing path is shortened, heat loss is reduced, and the heat exchange area is increased through shot blasting treatment; a multi-layer expansion joint structure is arranged to absorb vibration energy, and the service life of equipment is prolonged; the leakage rate is reduced by adopting a dual-sealing mechanism; and safe and continuous operation of the system is ensured through linkage of the liquid level switch and the temperature control switch. Compared with the prior art, the ammonia gas conversion rate can be increased, the operation and maintenance cost can be reduced, the structural stability and sealing performance can be improved, and the requirements of long-period and high-load operation of an industrial denitration system can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid ammonia evaporation devices, in particular to a liquid ammonia evaporator for flue gas denitration. Background Art

[0002] Amid increasingly stringent environmental regulations, industrial sectors such as thermal power generation and steelmaking must strictly control nitrogen oxide (NOx) emissions. Selective catalytic reduction (SCR), a mainstream denitrification technology, significantly impacts denitrification efficiency. The performance of its core equipment, the liquid ammonia evaporator, is crucial. Traditional liquid ammonia evaporators, often using stainless steel coil-type heat exchangers, suffer from numerous drawbacks. The heat transfer medium flows over long distances within the slender coils, resulting in lower water temperature at the end. This leads to uneven heating of the liquid ammonia, fluctuating evaporation rates, and insufficient ammonia conversion. High water hardness can easily cause scaling on the coils, reducing heat transfer efficiency and causing blockages, requiring frequent downtime for cleaning and increasing maintenance costs. Vibration caused by evaporation can easily cause fatigue cracking at the connection between the coil and the tank, leading to ammonia leaks and posing a safety hazard. Traditional flange seals are susceptible to failure under vibration, and the coil material's poor corrosion resistance further exacerbates the risk of leakage. While existing technologies have mitigated these issues, they have failed to fundamentally address them. Consequently, an efficient, stable, and easy-to-maintain liquid ammonia evaporator is urgently needed to meet the long-term, high-load operation requirements of industrial denitrification systems.

[0003] Therefore, a liquid ammonia evaporator for flue gas denitrification is proposed. Summary of the Invention

[0004] The object of the present invention is to provide a liquid ammonia evaporator for flue gas denitrification, which stably converts liquid ammonia into ammonia gas through a U-shaped pipeline heat exchange unit, thereby improving the ammonia conversion rate and solving the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A liquid ammonia evaporator for flue gas denitrification, comprising:

[0007] Brackets, the upper ends of the two brackets are fixedly mounted with a tank body, the tank body is a horizontal tank body, the upper end of the tank body is fixedly mounted with a liquid ammonia pipe, the liquid ammonia pipe extends into the interior of the tank body, the end of the liquid ammonia pipe away from the tank body is connected to the liquid ammonia tank, a liquid pump is fixedly mounted on the liquid ammonia pipe, and an ammonia outlet is opened at the upper end of the tank body away from the liquid ammonia pipe;

[0008] A heat exchange unit is fixedly installed at one end of the tank body.

[0009] Preferably, the heat exchange unit includes a mounting port opened at one end of the tank body, the mounting port is fixedly connected to a pipe box by a flange, a mounting plate is arranged between the pipe box and the tank body, and the mounting plate is circular; a plurality of water inlets are evenly opened on the left half of the end face of the mounting plate close to the pipe box, and a plurality of water outlets corresponding to the water inlets are evenly opened on the right half, a partition is fixedly installed in the middle of the pipe box to separate the water inlet and the water outlet, and the plurality of water inlets and water outlets are connected to matching U-shaped pipes, and the plurality of U-shaped pipes are concentrically arranged inside the tank body; a water inlet pipe is fixedly connected to the outer wall of one side of the pipe box, and a water pump is installed on the water inlet pipe, and a water outlet pipe is fixedly connected to the outer wall of the other side of the pipe box, and the water inlet pipe and the water outlet pipe form a closed-loop water channel through the heating boiler.

[0010] Preferably, the pipe box and the tank body are connected via a flange.

[0011] Preferably, a water storage pipe is fixedly installed on the upper end of the heating boiler, a water pump 2 is fixedly installed on the water storage pipe, a plurality of temperature control switches for stabilizing the water temperature are fixedly installed in the heating boiler, the plurality of temperature control switches are electrically connected to the water pump 1, a liquid level switch 1 is fixedly installed on the inner wall of the heating boiler, and the liquid level switch 1 is electrically connected to the water pump 2.

[0012] Preferably, booster pumps are installed at each of the multiple water inlets.

[0013] Preferably, sealing gaskets are fixedly installed at both ends of the mounting plate.

[0014] Preferably, multiple layers of expansion joints are arranged side by side on the end face of the mounting plate, and each layer includes two expansion joints arranged in parallel, and the expansion joints are composed of a sliding section and a fixed section, and the sliding section is sealingly and slidably connected to the fixed section; the two ends of each expansion joint are respectively connected to the mounting plate and the U-shaped pipe through a bellows; the support frame is fixed between the multiple layers of expansion joints through a connecting head, and the bottom end of the support frame is connected to the bottom frame of the tank body through a fixed frame, and the tail of the bottom frame forms an overall limit through the tail plate; an arc-shaped rubber pad is sleeved between each layer of expansion joints, and the arc-shaped rubber pad is made of low-temperature resistant silicone rubber, and its inner concave surface forms a flexible bearing surface, and the multiple layers of U-shaped pipes are stacked in the flexible bearing surface.

[0015] Preferably, a plurality of liquid level switches 2 of different heights are fixedly mounted on one side support frame, and the plurality of liquid level switches 2 are electrically connected to the liquid pump.

[0016] Preferably, the U-shaped pipe is made of a copper pipe, and the outer surface of the U-shaped pipe is shot blasted to form a uniformly distributed pit structure; a rubber sealing sleeve is provided in the water inlet at the connection between the U-shaped pipe and the mounting plate, and the rubber sealing sleeve includes a rubber ring sleeved on the outer wall of the U-shaped pipe, and a water storage cavity is provided on the side of the rubber ring close to the U-shaped pipe; a curved water-absorbing expansion bag is embedded in the rubber ring, and a wavy metal shrapnel is provided in the water-absorbing expansion bag, and the water storage cavity is respectively connected to the outer wall of the U-shaped pipe and the water-absorbing expansion bag. When liquid penetrates into the water storage cavity, the water-absorbing expansion bag expands and squeezes the rubber ring to enhance the seal.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention abandons traditional coils and adopts concentrically arranged U-shaped pipes, which greatly shortens the hot water flow path and reduces heat loss. The surface of the U-shaped pipe is shot peened to form a micro-pit structure. On the one hand, it increases the heat exchange area with liquid ammonia, allowing the liquid ammonia to fully absorb the heat of hot water; on the other hand, the multi-layer expansion joint structure combined with the flexible bearing surface of the arc-shaped rubber pad enables vibration contact between the U-shaped pipe and liquid ammonia, breaking the laminar boundary layer and improving heat exchange efficiency.

[0019] 2. The support frame and the base frame form a rigid limiting structure to prevent the pipe from deforming at the joint due to its own weight, reduce the risk of leakage, extend the overall service life of the equipment, reduce the frequency of equipment replacement, and reduce the overall cost.

[0020] 3. A unique double sealing mechanism is adopted at the connection between the U-shaped pipe and the mounting plate. The metal shrapnel maintains the basic seal to ensure no leakage under normal working conditions. Once leakage occurs, the water-absorbing expansion bag expands when it comes into contact with water and squeezes the rubber ring to enhance the sealing effect. The pipe is made of copper pipe and is shot peened, which not only improves the surface hardness, but also enhances the corrosion resistance, ensures the stable operation of the equipment, and reduces safety accidents and economic losses caused by corrosion and leakage.

[0021] 4. The liquid level switch is linked to the temperature control switch to monitor and adjust the water temperature of the heating boiler and the amount of liquid ammonia injected in real time. When the water level in the heating boiler drops, the liquid level switch 1 controls the water pump 2 to replenish water in time. At the same time, the temperature control switch controls the water pump 1 to stop working, preventing the water temperature from being too low and affecting the liquid ammonia conversion efficiency, thus avoiding dry burning accidents. The liquid level switch 2 monitors the liquid level in the tank to realize automatic replenishment of liquid ammonia and avoid liquid ammonia overflow, thus ensuring the safe and continuous operation of the system, reducing manual intervention, and improving the level of automation and production safety.

[0022] 5. Multiple liquid level switches are combined with multiple layers of U-shaped pipes arranged at different heights. The number of U-shaped pipes involved in heat exchange can be flexibly adjusted according to the liquid ammonia processing capacity. When processing a small amount of liquid ammonia, only the bottom layer of U-shaped pipes will work, reducing the amount of hot water circulation and the energy consumption of the heating boiler. When processing a large amount of liquid ammonia, more layers of U-shaped pipes will participate in heat exchange to ensure that the liquid ammonia evaporates quickly and fully, meeting the different load requirements of the denitrification system, achieving energy saving and consumption reduction, and improving energy utilization efficiency.

[0023] 6. The pipe box and the tank body are connected by a flange, and the mounting plate is located between the two. This detachable design makes it easy to separate the pipe box and the tank body when the internal pipes of the tank body are blocked or damaged, so as to quickly repair or replace the internal parts. In addition, the booster pump flushes impurities inside the U-shaped pipe, and hot water sloshes to prevent scale deposition. These designs reduce pipe blockage and scaling problems, reduce the frequency and difficulty of maintenance, and improve the continuity of equipment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0025] Figure 2 It is a front view structural schematic diagram of the present invention;

[0026] Figure 3 Schematic diagram of the structure of the pipe box;

[0027] Figure 4 It is a structural diagram of a heating boiler;

[0028] Figure 5 It is a right side structural schematic diagram of the present invention;

[0029] Figure 6 for Figure 5 Schematic diagram of the AA section structure;

[0030] Figure 7 This is a schematic diagram of the U-shaped pipe installation structure;

[0031] Figure 8 It is an enlarged schematic diagram of the expansion joint;

[0032] Figure 9 for Figure 8 Schematic diagram of the BB cross-section structure;

[0033] Figure 10 It is a structural diagram of the telescopic structure on the telescopic joint;

[0034] Figure 11 Schematic diagram of the cross-sectional structure of the rubber sealing sleeve.

[0035] Figure 1: 1. Bracket, 2. Tank, 3. Liquid ammonia pipe, 4. Liquid pump, 5. Ammonia outlet, 6. Mounting port, 7. Pipe box, 8. Mounting plate, 9. Water inlet, 10. Water outlet, 11. Partition, 12. U-shaped pipe, 13. Water inlet pipe, 14. Water pump 1, 15. Water outlet pipe, 16. Heating boiler, 17. Temperature control switch, 18. Sealing gasket, 19. Support frame, 20. Liquid level switch 1, 2 5. Water storage pipe, 26. Water pump 2, 27. Liquid level switch 2, 28. Booster pump, 30. Base frame, 31. Fixed frame, 32. Telescopic joint, 321. Sliding section, 322. Fixed section, 33. Connector, 34. Bellows, 35. Tail plate, 36. Curved rubber pad, 37. Rubber sealing sleeve, 371. Rubber ring, 372. Water absorption expansion bladder, 373. Metal shrapnel, 374. Water storage chamber. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] See also Figures 1 to 11 The present invention provides a liquid ammonia evaporator for flue gas denitrification, and the technical solution is as follows:

[0038] A liquid ammonia evaporator for flue gas denitrification, comprising:

[0039] Bracket 1, a tank body 2 is fixedly mounted on the upper ends of the two brackets 1. The tank body 2 is a horizontal tank body 2. A liquid ammonia pipe 3 is fixedly mounted on the upper end of the tank body 2. The liquid ammonia pipe 3 extends into the interior of the tank body 2. The end of the liquid ammonia pipe 3 away from the tank body 2 is connected to the liquid ammonia tank. A liquid extraction pump 4 is fixedly mounted on the liquid ammonia pipe 3. An ammonia outlet 5 is opened at the upper end of the tank body 2 away from the liquid ammonia pipe 3.

[0040] A heat exchange unit is fixedly installed at one end of the tank body 2.

[0041] Existing liquid ammonia evaporators for flue gas denitrification often use coiled water pipes for heat exchange. These slender pipes require long distances for hot water transport, leaving the water at the end of the pipes already cooled. Furthermore, frequent pipe blockages result in poor heat exchange efficiency. The liquid ammonia evaporator for flue gas denitrification in the present invention comprises two supports 1 supporting a horizontal tank 2. A pump 4 draws liquid ammonia from the tank and transports it to the interior of the tank 2. A heat exchange unit steadily converts the liquid ammonia into ammonia gas, which is then discharged through an ammonia outlet 5 and enters the next tank, where it mixes with the flue gas for denitrification. This improves ammonia conversion and treatment efficiency.

[0042] Reference Figure 1-7 The heat exchange unit includes a mounting port 6 opened at one end of the tank body 2, and a pipe box 7 is fixedly connected to the mounting port 6 by a flange. A mounting plate 8 is provided between the pipe box 7 and the tank body 2, and the mounting plate 8 is circular; a plurality of water inlets 9 are evenly opened on the left half of the end face of the mounting plate 8 close to the pipe box 7, and a plurality of water outlets 10 are evenly opened on the right half, which correspond to the water inlets 9 one by one. A partition 11 is fixedly installed in the middle of the pipe box 7 to separate the water inlet 9 and the water outlet 10, and the plurality of water inlets 9 and the water outlet 10 are connected with matching U-shaped pipes 12, and the plurality of U-shaped pipes 12 are concentrically arranged inside the tank body 2; an outer wall on one side of the pipe box 7 is fixedly connected to a water inlet pipe 13, and a water pump 14 is installed on the water inlet pipe 13, and an outer wall on the other side of the pipe box 7 is fixedly connected to a water outlet pipe 15, and the water inlet pipe 13 and the water outlet pipe 15 form a closed-loop water channel through the heating boiler 16.

[0043] The liquid ammonia evaporator for flue gas denitrification in the existing technology mostly uses disc-type water pipes for heat exchange. The water pipes are slender, and hot water needs to be transported over a long distance in the water pipes. The water at the end of the water pipes has already cooled down. The water pump 14 draws the hot water in the heating boiler 16 from the water inlet pipe 13 at the upper end of the pipe box 7 into the pipe box 7 and passes through the inner area of ​​the partition 11. The U-shaped pipe 12 is filled from the water inlet 9 to perform heat exchange on the liquid ammonia injected into the tank body 2. The liquid ammonia then enters the outer area of ​​the partition 11 in the pipe box 7 from the water outlet 10 at the end of the U-shaped pipe 12, and then enters the heating boiler 16 from the water outlet pipe 15 to form a hot water circulation. Compared with the disc-type pipes, the hot water travel distance of multiple U-shaped pipes 12 is shorter, the heat exchange is more uniform and stable, and the ammonia conversion rate is improved.

[0044] As an embodiment of the present invention, refer to Figure 1 The pipe box 7 and the tank body 2 are connected by a flange.

[0045] The pipe box 7 and the tank body 2 are connected by a flange, and the mounting plate 8 is installed between the pipe box 7 and the tank body 2. The flange connection realizes detachable installation. If the internal pipe of the tank body 2 is blocked or damaged, the tank body 2 and the pipe box 7 can be separated to facilitate the maintenance of the parts inside the tank body 2.

[0046] As an embodiment of the present invention, refer to Figure 4 A water storage pipe 25 is fixedly installed on the upper end of the heating boiler 16, and a water pump 26 is fixedly installed on the water storage pipe 25. A plurality of temperature control switches 17 for stabilizing the water temperature are fixedly installed in the heating boiler 16. The plurality of temperature control switches 17 are electrically connected to the water pump 14. A liquid level switch 20 is fixedly installed on the inner wall of the heating boiler 16, and the liquid level switch 20 is electrically connected to the water pump 26.

[0047] The heating boiler 16 heats hot water and circulates water inside the pipe. There is heat loss during the hot water circulation process, which will cause the liquid level to continue to drop, and may cause dry burning, resulting in a safety accident. When the liquid level is lower than the liquid level switch 20, the water pump 26 is automatically turned on to inject water into the boiler. During the water injection process, the water temperature inside the boiler will drop rapidly. In order to prevent the water temperature from being too low when entering the U-shaped pipe 12 inside the tank body 2, affecting the efficiency of liquid ammonia conversion to ammonia gas, the water pump 14 is temporarily stopped from pumping water into the pipe box 7 to prevent the temperature inside the tank body 2 from dropping sharply and affecting the ammonia conversion rate.

[0048] As an embodiment of the present invention, refer to Figure 7 , booster pumps 28 are installed at each of the multiple water inlets 9.

[0049] The water inside the pipe box 7 is pumped by a single pump 14, and the water pressure is difficult to support the rapid flow of water inside the U-shaped pipe 12. Booster pumps 28 are installed at multiple water inlets 9. On the one hand, it can promote thermal efficiency conversion. On the other hand, the strong water pressure can flush out impurities inside the U-shaped pipe 12, significantly improve the ammonia conversion rate, and supply flue gas reaction treatment.

[0050] As an embodiment of the present invention, refer to Figure 6 Sealing gaskets 18 are fixedly installed at both ends of the mounting plate 8.

[0051] Sealing gaskets 18 are fixedly installed at both ends of the mounting plate 8. The liquid ammonia in the tank body 2 must maintain purity. If the sealing gasket 18 is not installed, the probability of water seepage and leakage will be relatively high. The contaminated liquid ammonia will affect the efficiency of ammonia conversion, thereby affecting the speed of flue gas denitrification.

[0052] As an embodiment of the present invention, refer to Figure 6-10 , multi-layer telescopic joints 32 are arranged side by side on the end face of the mounting plate 8, and each layer includes two parallel telescopic joints 32, and the telescopic joint 32 consists of a sliding section 321 and a fixed section 322, and the sliding section 321 is sealed and slidably connected to the fixed section 322; the two ends of each telescopic joint 32 are respectively connected to the mounting plate 8 and the U-shaped pipe 12 through a bellows 34; the multi-layer telescopic joints 32 are fixed with the support frame 19 through a connector 33, and the bottom end of the support frame 19 is connected to the bottom frame 30 of the tank body 2 through a fixed frame 31, and the tail of the base frame 30 is limited as an integral whole by a tail plate 35; an arc-shaped rubber pad 36 is sleeved between each layer of telescopic joints 32, and the arc-shaped rubber pad 36 is made of low-temperature resistant silicone rubber, and its inner concave surface forms a flexible bearing surface, and the multi-layer U-shaped pipe 12 is stacked in the flexible bearing surface.

[0053] When the liquid ammonia evaporates and generates vibrations, this multi-layer "stretcher-like" structure, in conjunction with the bellows 34 and the telescopic structure on the telescopic joint 32, provides a certain amount of movement space for the U-shaped pipe 12. The U-shaped pipe 12 can shake within a certain range, so that the liquid ammonia in the tank and the hot water in the U-shaped pipe 12 can both oscillate within a certain range, further improving the heat exchange efficiency.

[0054] Specifically, when liquid ammonia evaporates, it will produce a certain amount of shaking, thereby causing the U-shaped pipe 12 inside the liquid ammonia to vibrate. The sliding section 321 of the expansion joint 32 will vibrate slightly under the elastic compensation of the bellows 34, so that the U-shaped pipe 12 can shake slightly. The flexible bearing surface of the arc-shaped rubber pad 36 makes the U-shaped pipe 12 and the liquid ammonia in vibration contact, breaking the laminar boundary layer, intensifying the collision effect of the hot water in the pipe, improving the heat exchange efficiency, protecting the U-shaped pipe 12 from damage and reducing noise. At the same time, the swaying of hot water inside the U-shaped pipe 12 can effectively prevent scale from depositing on the inner wall of the pipe, and can generate a certain impact force on the scale already attached to the inner wall of the pipe, causing longer scale to break into scale fragments, which are then more easily separated from the inner wall of the U-shaped pipe 12 under the shaking action of the hot water, further reducing scale deposition.

[0055] In addition, the rigid fixation of the support frame 19 and the base frame 30 avoids stress concentration at the connection of the U-shaped pipe 12 due to its own weight, reducing the risk of damage. The tail is limited by the tail plate 35, further improving the stability of the overall structure.

[0056] As an embodiment of the present invention, refer to Figure 6-9 A plurality of liquid level switches 27 of different heights are fixedly mounted on one side support frame 19 , and the plurality of liquid level switches 27 are electrically connected to the liquid pump 4 .

[0057] The liquid pump 4 extracts liquid ammonia and transports it to the tank body 2. Since the tank body 2 is a closed space, the internal liquid injection situation cannot be observed. If the liquid injection is too little, the amount of ammonia produced will be greatly affected. If the liquid injection is too much, even higher than the ammonia outlet 5, although ammonia will be produced, it will also prevent the ammonia from being discharged, and the pressure in the tank will increase, causing certain safety risks. The liquid level of the liquid ammonia in the tank body 2 is monitored by the liquid level switch 27, and automatic replenishment of liquid ammonia is realized. That is, when the liquid ammonia level is lower than the liquid level set by the liquid level switch 27, the controller controls the liquid pump 4 to replenish liquid ammonia. Otherwise, it proves that the liquid ammonia is sufficient and no replenishment is needed, thereby improving safety.

[0058] Multiple liquid level switches 27 are installed at different heights, and are arranged horizontally at different heights with multiple layers of U-shaped pipes 12. This can improve the flexibility and efficiency of equipment operation and reduce energy consumption. When processing a small amount of liquid ammonia, only the bottom U-shaped pipe 12 works, which can avoid idling energy consumption of the upper pipe, reduce the amount of hot water circulation, and reduce the energy consumption of the heating boiler; and because the amount of liquid ammonia is small, the heat exchange of the bottom pipe is sufficient to meet the demand, avoiding unnecessary energy waste; when processing a large amount of liquid ammonia, the rising liquid level triggers more liquid level switches 27, so that more layers of U-shaped pipes 12 participate in heat exchange, ensuring that the liquid ammonia can evaporate quickly and fully, meeting the high-load operation requirements of the denitrification system, ensuring a stable supply of ammonia, and avoiding safety risks caused by liquid ammonia accumulation.

[0059] As an embodiment of the present invention, refer to Figure 11 The U-shaped pipe 12 is made of a copper pipe, and the outer surface of the U-shaped pipe 12 is shot blasted to form a uniformly distributed pit structure; a rubber sealing sleeve 37 is provided in the water inlet 9 at the connection between the U-shaped pipe 12 and the mounting plate 8, and the rubber sealing sleeve 37 includes a rubber ring 371 sleeved on the outer wall of the U-shaped pipe 12, and a water storage cavity 374 is provided on the side of the rubber ring 371 close to the U-shaped pipe 12, and a curved water absorption expansion bag 372 is embedded in the rubber ring 371, and a wavy metal spring 373 is provided in the water absorption expansion bag 372, and the water storage cavity 374 is respectively connected to the outer wall of the U-shaped pipe 12 and the water absorption expansion bag 372; when liquid penetrates into the water storage cavity 374, the water absorption expansion bag 372 expands and squeezes the rubber ring 371 to enhance the seal.

[0060] During the evaporation process of liquid ammonia in the tank, the liquid ammonia will naturally vibrate. In this embodiment, the surface of the U-shaped pipe 12 is shot peened to form a plurality of pits. These pits increase the heat exchange area between the liquid ammonia and the U-shaped pipe 12, allowing the liquid ammonia to more fully absorb the heat of the hot water in the U-shaped pipe 12 and accelerate the evaporation rate. In addition, the presence of the pits enhances the vibration effect. When the liquid ammonia vibrates, this surface structure can better transmit the vibration energy, further promoting the heat exchange between the liquid ammonia and the hot water, and improving the heat exchange efficiency.

[0061] Under normal circumstances, the wavy metal spring 373 inside the rubber ring 371 plays a role in stabilizing the deformation and ensuring that the rubber sealing sleeve 37 can maintain a normal sealing state when the U-shaped pipe 12 shakes;

[0062] Once leakage occurs, the water at the water inlet 9 will quickly enter the water storage chamber 374 inside the rubber ring 371, and then further flow to the water absorption expansion bag 372. The inflow of water will cause the water absorption expansion bag 372 to expand, and then squeeze the rubber ring 371, making it more closely attached to the outer wall of the U-shaped pipe 12, thereby enhancing the sealing effect and playing a second sealing role.

[0063] Working principle: The liquid ammonia evaporator for flue gas denitrification in the prior art mostly uses disc-type water pipes for heat exchange. The water pipes are slender, and hot water has to be transported over a long distance in the water pipes. The water at the end of the water pipes has already cooled down, and the water pipes are frequently blocked, resulting in poor heat exchange efficiency. The liquid ammonia evaporator for flue gas denitrification in the present invention is a horizontal tank body 2 supported by two brackets 1. Liquid ammonia is extracted from the liquid ammonia tank by a liquid pump 4 and transported to the inside of the tank body 2. The liquid ammonia is stably converted into ammonia gas through a heat exchange unit. The ammonia gas is then discharged from the ammonia outlet 5 and enters the next tank body to mix with the flue gas for denitrification. , the water pump 14 draws the hot water in the heating boiler 16 from the water inlet pipe 13 at the upper end of the pipe box 7 into the pipe box 7 and passes through the inner area of ​​the partition 11, fills the U-shaped pipe 12 from the water inlet 9, and performs heat exchange with the liquid ammonia injected into the tank body 2. The hot water is then discharged from the water outlet 10 at the end of the U-shaped pipe 12, enters the outer area of ​​the partition 11 in the pipe box 7, and then enters the heating boiler 16 from the water outlet pipe 15 to form a hot water circulation. Compared with the disc pipe, the multiple U-shaped pipes 12 have a shorter hot water travel distance, more uniform and stable heat exchange, and can improve the ammonia conversion rate;

[0064] The heating boiler 16 heats hot water and circulates water inside the pipe. During the hot water circulation process, there is heat loss, which will cause the liquid level to continue to drop, which may cause dry burning and cause safety accidents. When the liquid level is lower than the liquid level switch 20, the water pump 26 is automatically turned on to inject water into the boiler. During the water injection process, the water temperature inside the boiler will drop rapidly. In order to prevent the water temperature from being too low when entering the U-shaped pipe 12 inside the tank body 2 and affecting the efficiency of liquid ammonia conversion to ammonia gas, the water pump 14 is temporarily stopped from pumping water into the pipe box 7 to prevent the temperature from dropping suddenly. The water inside the pipe box 7 is pumped by only one water pump 14. The water pressure is difficult to support the rapid flow of water inside the U-shaped pipe 12. Booster pumps 28 are installed at multiple water inlets 9. On the one hand, it promotes thermal efficiency conversion. On the other hand, the strong water pressure can flush out impurities inside the U-shaped pipe 12, significantly improving the ammonia conversion rate and supplying it to the flue gas reaction treatment.

[0065] When the liquid ammonia in the tank body 2 evaporates, it vibrates. The multi-layer "stretcher-like" stacking structure, combined with the bellows 34 and telescopic structure on the telescopic joint 32, provides a certain amount of space for the U-shaped pipe 12 to move. The U-shaped pipe 12 can shake within a certain range, so that the liquid ammonia in the tank body and the hot water in the U-shaped pipe 12 can both oscillate within a certain range, further improving the heat exchange efficiency. The flexible bearing surface of the arc-shaped rubber pad 36 allows the U-shaped pipe 12 to vibrate with the liquid ammonia, breaking the laminar boundary layer, improving the heat exchange efficiency, protecting the U-shaped pipe 12 from damage and reducing noise. The surfaces of the multiple copper U-shaped pipes 12 are shot-peened, which not only increases the heat exchange area with the liquid ammonia, but also enhances the vibration effect and promotes heat exchange. The swaying of hot water inside the U-shaped pipe 12 can effectively prevent scale from depositing on the inner wall of the pipe and can generate a certain impact force on the scale already attached to the inner wall of the pipe, causing longer scale to break into scale fragments, which are then more easily separated from the inner wall of the U-shaped pipe 12 by the shaking of the hot water, further reducing scale deposition.

[0066] The liquid pump 4 extracts liquid ammonia and transports it to the tank body 2. Since the tank body 2 is a closed space, the internal liquid filling situation cannot be observed. If the liquid is too little, the amount of ammonia gas produced will be greatly affected. If the liquid is too much, even higher than the ammonia outlet 5, although ammonia gas will be produced, it will also prevent the ammonia gas from being discharged, and the pressure in the tank will increase, causing certain safety risks. The liquid level switch 27 is used to monitor the liquid ammonia level in the tank body 2 and realize automatic replenishment of liquid ammonia. That is, when the liquid ammonia level is lower than the liquid level set by the liquid level switch 27, the controller controls the liquid pump 4 to replenish liquid ammonia. Otherwise, it proves that the liquid ammonia is sufficient and does not need to be replenished, thereby improving safety. Multiple liquid level switches 27 are combined with multiple layers of U-shaped pipes 12 arranged at different heights. The number of U-shaped pipes 12 participating in heat exchange can be flexibly adjusted according to the liquid ammonia processing capacity, thereby achieving energy saving and consumption reduction and ensuring a stable supply of ammonia gas under different working conditions.

[0067] Sealing gaskets 18 are fixedly installed at both ends of the mounting plate 8. The liquid ammonia in the tank body 2 must maintain purity. If the sealing gaskets 18 are not installed, the probability of water seepage and leakage will be relatively high. The metal spring 373 in the rubber sealing sleeve 37 at the water inlet 9 maintains the seal under normal circumstances. In the event of leakage, the liquid in the water storage chamber 374 flows to the water absorption expansion bag 372 to expand it, thereby enhancing the sealing effect, effectively preventing liquid leakage, and ensuring the normal operation of the equipment and the purity of the liquid ammonia.

[0068] The pipe box 7 is connected to the tank body 2 by a flange, and the mounting plate 8 is installed between the pipe box 7 and the tank body 2. The flange connection realizes detachable installation. If the internal pipe of the tank body 2 is blocked or damaged, the tank body 2 and the pipe box 7 can be separated, which is convenient for repairing the parts inside the tank body 2; a base frame 30 for supporting the U-shaped pipe 12 is fixedly installed on the bottom surface of the tank body 2. The U-shaped pipe 12 has a certain dead weight, and the U-shaped pipe 12 extends to a certain length in the tank body 2. After long-term use, the connection between the U-shaped pipe 12 and the mounting plate 8 will be deformed and easily damaged. The base frame 30 and the tail plate 35 are provided to support and limit the U-shaped pipe 12 in the horizontal direction to prevent the damage of the pipe connection causing the damage of the U-shaped pipe 12.

[0069] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A liquid ammonia evaporator for flue gas denitrification, comprising: A bracket (1), a tank body (2) is fixedly mounted on the upper ends of the two brackets (1), the tank body (2) is a horizontal tank body (2), a liquid ammonia pipe (3) is fixedly mounted on the upper end of the tank body (2), the liquid ammonia pipe (3) extends into the interior of the tank body (2), one end of the liquid ammonia pipe (3) away from the tank body (2) is connected to the liquid ammonia tank, a liquid pump (4) is fixedly mounted on the liquid ammonia pipe (3), and an ammonia outlet (5) is provided at the upper end of the tank body (2) away from the liquid ammonia pipe (3); a heat exchange unit is fixedly mounted on one end of the tank body (2); The invention is characterized in that: the heat exchange unit includes a mounting port (6) opened at one end of the tank body (2); the mounting port (6) is fixedly connected to a pipe box (7) through a flange; a mounting plate (8) is provided between the pipe box (7) and the tank body (2); the mounting plate (8) is circular; a plurality of water inlets (9) are evenly provided on the left half of the end face of the mounting plate (8) close to the pipe box (7); a plurality of water outlets (10) corresponding to the water inlets (9) are evenly provided on the right half; a partition (11) is fixedly installed in the middle of the pipe box (7) to separate the water inlets (9) and the water outlets (10); the plurality of water inlets (9) and the water outlets (10) are all connected to matching U-shaped pipes (12); and the plurality of U-shaped pipes (12) are concentrically arranged inside the tank body (2).

2. The liquid ammonia evaporator for flue gas denitrification according to claim 1, characterized in that: An inlet pipe (13) is fixedly connected to the outer wall of one side of the pipe box (7), and a water pump (14) is installed on the inlet pipe (13). An outlet pipe (15) is fixedly connected to the outer wall of the other side of the pipe box (7). The inlet pipe (13) and the outlet pipe (15) form a closed-loop water circuit through a heating boiler (16).

3. The liquid ammonia evaporator for flue gas denitrification according to claim 2, characterized in that: A water storage pipe (25) is fixedly installed on the upper end of the heating boiler (16), and a second water pump (26) is fixedly installed on the water storage pipe (25). A plurality of temperature control switches (17) for stabilizing the water temperature are fixedly installed in the heating boiler (16), and the plurality of temperature control switches (17) are electrically connected to the first water pump (14). A liquid level switch (20) is fixedly installed on the inner wall of the heating boiler (16), and the liquid level switch (20) is electrically connected to the second water pump (26).

4. The liquid ammonia evaporator for flue gas denitrification according to claim 2, characterized in that: Multiple layers of telescopic joints (32) are arranged side by side on the end surface of the mounting plate (8), and each layer includes two parallel telescopic joints (32). The telescopic joints (32) are composed of a sliding section (321) and a fixed section (322), and the sliding section (321) is sealed and slidably connected to the fixed section (322); the two ends of each telescopic joint (32) are respectively connected to the mounting plate (8) and the U-shaped pipe (12) through a bellows (34); a support frame (19) is fixed between the multiple layers of telescopic joints (32) through a connector (33), and the bottom end of the support frame (19) is connected to the bottom frame (30) of the tank body (2) through a fixed frame (31), and the tail of the bottom frame (30) forms an integral limit through a tail plate (35).

5. The liquid ammonia evaporator for flue gas denitrification according to claim 4, characterized in that: An arc-shaped rubber pad (36) is sleeved between each layer of the telescopic joints (32). The arc-shaped rubber pad (36) is made of low-temperature resistant silicone rubber, and its inner concave surface forms a flexible bearing surface. Multiple layers of the U-shaped pipes (12) are stacked on the flexible bearing surface.

6. The liquid ammonia evaporator for flue gas denitrification according to claim 4, characterized in that: A plurality of liquid level switches (27) of different heights are fixedly mounted on the support frame (19) on one side, and the plurality of liquid level switches (27) are all electrically connected to the liquid pump (4).

7. The liquid ammonia evaporator for flue gas denitrification according to claim 2, characterized in that: The U-shaped pipe (12) is made of a copper pipe, and the outer surface of the U-shaped pipe (12) is shot blasted to form a pit structure.

8. The liquid ammonia evaporator for flue gas denitrification according to claim 2, characterized in that: A rubber sealing sleeve (37) is provided in the water inlet (9) at the connection between the U-shaped pipe (12) and the mounting plate (8), and the rubber sealing sleeve (37) comprises a rubber ring (371) sleeved on the outer wall of the U-shaped pipe (12).

9. The liquid ammonia evaporator for flue gas denitrification according to claim 8, characterized in that: A water storage cavity (374) is provided on one side of the rubber ring (371) close to the U-shaped pipe (12). A curved water-absorbing expansion bag (372) is embedded in the rubber ring (371). A wavy metal spring (373) is provided in the water-absorbing expansion bag (372). The water storage cavity (374) is communicated with the outer wall of the U-shaped pipe (12) and the water-absorbing expansion bag (372) through a channel. When liquid penetrates into the water storage cavity (374), the water-absorbing expansion bag (372) expands and squeezes the rubber ring (371) to enhance the seal.

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