Neutralization system for ammonium nitrate production

Abstract

The utility model relates to the technical field of ammonium nitrate production, in particular to an ammonium nitrate production neutralization system. Comprising a neutralizer, a nitric acid pipeline and an ammonia gas pipeline, the nitric acid pipeline and the ammonia gas pipeline are connected with the neutralizer, a reaction area, a filler reaction separation area and a purification area are sequentially arranged in the neutralizer from bottom to top, a guide cylinder is arranged in the center of the lower portion of the neutralizer, and the top of the guide cylinder is covered with a conical baffle. A nitric acid pipeline enters the guide cylinder and is connected with a nitric acid liquid spraying head, the nitric acid liquid spraying head is arranged above the gas distributor, the filler reaction separation area is arranged above the conical baffle, the purification area is a demister arranged above the filler pressing plate, and a bubble-free overflow discharging device is arranged on the side wall of the neutralizer. Through the integrated and multi-area structural design, efficient mixing of reaction materials, multi-stage deep separation of gas-liquid products, bubble-free stable discharge of product feed liquid and maximum closed-loop recovery of reaction heat energy are realized.

Description

Technical Field

[0001] This utility model relates to the field of ammonium nitrate production technology, specifically to an ammonium nitrate production neutralization system. Background Technology

[0002] Ammonium nitrate, as a basic chemical raw material, plays an important role in agriculture and industry. Its industrial production mainly relies on the neutralization reaction of dilute nitric acid and ammonia. This reaction process is violently exothermic, accompanied by phase changes and rapid volume expansion of the materials, making reactor design and control the core and challenge of the entire production process.

[0003] Currently, the neutralization processes and equipment commonly used in the industry still face the following technical bottlenecks that urgently need improvement:

[0004] Traditional batch reactors or simple tubular reactors struggle to achieve instantaneous, uniform mixing of materials at both the macroscopic and microscopic levels. This easily leads to localized areas of excessive acidity or alkalinity within the reactor. Localized excessive acidity accelerates equipment corrosion and shortens equipment lifespan; while localized excessive alkalinity promotes the decomposition of ammonium nitrate, generating highly unstable ammonium nitrite, which poses a significant safety hazard of explosion under high temperature and pressure. Achieving uniform mixing under vigorous reaction conditions is the primary challenge for ensuring safe production.

[0005] The immense heat released during the neutralization reaction vaporizes a large amount of water, forming secondary steam with considerable calorific value. However, due to the vigorous boiling of the reaction, this secondary steam often carries a large amount of ammonium nitrate solution droplets. If directly used to heat downstream equipment, such as heating equipment in the evaporation and concentration section, or to preheat raw materials, this ammonium nitrate-containing "wet steam" will crystallize and scale on the heat exchange surfaces, severely reducing heat exchange efficiency, increasing the frequency and cost of cleaning and maintenance, and significantly diminishing the effectiveness of the energy recovery system, making long-term, high-efficiency operation impossible.

[0006] If ammonium nitrate droplets entrained in the steam are not completely separated and are discharged with the steam, it will not only directly cause product loss and reduce material yield, but also cause pollution and corrosion to the subsequent condensation system, and may also affect the atmospheric environment when discharged with exhaust steam.

[0007] The liquid product discharged from a violently boiling reactor inevitably contains a large number of unseparated microbubbles. This two-phase flow of material introduces significant errors into level measurement, causing frequent fluctuations and instability in the level control system. More seriously, it causes severe cavitation in downstream transfer pumps, severely wearing down critical components such as impellers, greatly shortening pump lifespan, and even triggering unplanned shutdowns.

[0008] Therefore, the market urgently needs a new type of ammonium nitrate neutralization system that can fundamentally solve the multiple challenges of safety, efficiency, environmental protection and stability mentioned above, and achieve a high degree of process integration and optimization. Utility Model Content

[0009] To address the shortcomings of existing technologies, this invention provides a neutralization system for ammonium nitrate production. Through an integrated, multi-zone structural design, it aims to achieve efficient mixing of reactants, multi-stage deep separation of gaseous and liquid products, stable, bubble-free discharge of the product liquid, and maximized closed-loop recovery of reaction heat.

[0010] To solve the above problems, the technical solution of this utility model is:

[0011] The ammonium nitrate production neutralization system of this utility model includes a neutralizer, and nitric acid and ammonia pipelines connected to the neutralizer. An ammonia filter and an ammonia preheater are sequentially installed on the ammonia pipeline, which is connected to an ammonia inlet in the middle of the neutralizer. A nitric acid storage tank and a nitric acid preheater are sequentially installed on the nitric acid pipeline. The neutralizer contains, from bottom to top, a reaction zone, a packing reaction separation zone, and a purification zone. A guide tube is located at the lower center of the neutralizer, and the guide tube is fixed to the bottom of the neutralizer by support legs. Its lower edge is connected to the neutralization... A gap is left between the bottom end caps of the device. The top of the guide tube is covered with a conical baffle with an opening at the top. After the ammonia pipeline enters the neutralizer, it enters the guide tube from the bottom side wall and connects to the upward-facing gas distributor. The nitric acid pipeline enters the neutralizer through the nitric acid inlet and then enters the guide tube from the bottom side wall and connects to the nitric acid spray head, which is located above the gas distributor. The packing reaction separation zone is located above the conical baffle. The side wall of the neutralizer is equipped with a bubble-free overflow discharge device.

[0012] This system constructs a highly efficient air-lift internal circulation reactor. The guide tube and its outer annular gap constitute the core circulation loop. The steam generated by the reaction generates a powerful air-lift force within the guide tube, driving the feed liquid to circulate at extremely high speeds in an "upper inside, lower outside" manner. This intense turbulence ensures uniform mixing of the acid and ammonia feedstocks, eliminating the possibility of localized over-acidity or over-alkaliness from the source, and achieving inherent safety in the process.

[0013] The packing reaction separation zone includes Pall ring packing located above the conical baffle, and the Pall ring packing is disposed between the packing support plate and the packing pressure plate.

[0014] The purification zone is a demister located above the packing pressure plate, and the evaporation steam outlet of the neutralizer is located above the demister.

[0015] First, the high-speed gas-liquid flow impacts the conical baffle, changing its direction. Most droplets are thrown out and fall back due to inertia. The airflow passes through the Pall ring packing layer. On one hand, the Pall ring packing captures and neutralizes any trace amounts of unreacted ammonia that may escape from the gas phase, ensuring the purity of the discharged steam and preventing ammonia loss and corrosion of downstream equipment. On the other hand, it also intercepts and buffers any acidic droplets that may be entrained, stabilizing pH fluctuations through mixing with the bulk solution. Simultaneously, the ample gas-liquid contact within the Pall ring packing layer enhances heat transfer, resulting in a more uniform temperature distribution throughout the separation zone. Finally, the tiny droplets repeatedly collide, coalesce, grow, and fall back onto the packing surface, achieving high capture efficiency and efficient secondary fine separation. The top demister ultimately captures the remaining extremely fine droplets.

[0016] The bubble-free overflow discharge device includes an overflow weir box located outside the neutralizer. The overflow weir box extends to the bottom of the neutralizer via a drain pipe, leaving a gap between the drain pipe and the bottom. A guide pipe is fitted over the drain pipe, and gaps are provided between the bottom and sidewall of the drain pipe and the guide pipe. An overflow outer pipe is provided outside the guide pipe, with its bottom extending to the bottom of the neutralizer. An inlet is opened on the bottom sidewall of the overflow outer pipe, and the bottom of the overflow weir box is the outlet.

[0017] The upper edge of the overflow pipe is higher than the upper edge of the guide pipe.

[0018] The U-shaped flow channel design inside the bubble-free overflow discharge device forces the product liquid to undergo a slow "rise-overflow-fall" flow process. During this process, the tiny bubbles in the liquid have ample time and space to rise due to buoyancy and separate from the mainstream liquid. Ultimately, what is discharged from the drain pipe is a pure, bubble-free single-phase liquid flow. This not only ensures precise and reliable liquid level control but also fundamentally eliminates cavitation problems in downstream pumps, guaranteeing the long-term safe and stable operation of the entire production line.

[0019] The inner wall of the guide tube is horizontally provided with several layers of perforated sieve plates.

[0020] The multi-layer perforated sieve plate inside the guide tube further shears the rising large bubbles into smaller bubbles, increasing the gas-liquid mass transfer area, making the reaction more complete and the cycle more stable.

[0021] The neutralizer has an upper manhole at the top and a lower manhole at the bottom.

[0022] The steam transport pipelines at the top of the overflow weir box and the top of the neutralizer are divided into three pipelines: a first steam pipeline connected to the ammonia preheater, a second steam pipeline connected to the nitric acid preheater, and a third steam pipeline connected to the evaporator.

[0023] Thanks to the high-quality secondary steam, this system achieves a high degree of energy self-sufficiency and comprehensive utilization. Steam directly provides heat to the ammonia preheater and nitric acid preheater through the first and second steam pipelines, forming an internal energy cycle. Excess clean steam is transported to the downstream evaporation and concentration section through the third steam pipeline, replacing expensive external energy sources. This significantly reduces the plant's utility consumption and production costs, resulting in substantial economic benefits.

[0024] The liquid product at the bottom of the overflow weir box is transported to the evaporation and concentration section.

[0025] The beneficial effects of this utility model are as follows:

[0026] (1) This utility model adopts a three-stage series deep separation strategy of "inertia + packing + wire mesh". This combination ensures that the secondary steam discharged from the evaporation steam outlet is highly pure and dry, providing a high-quality heat source with quality comparable to fresh steam for the downstream energy recovery system.

[0027] (2) The multi-layer perforated sieve plate set in the guide tube of this utility model further shears the rising large bubbles into small bubbles, increases the gas-liquid mass transfer area, and makes the reaction more complete and the cycle more stable.

[0028] (3) The high-quality secondary steam generated by this invention directly provides heat energy to the ammonia preheater and nitric acid preheater of this system through the first steam pipeline and the second steam pipeline, forming an internal energy cycle. The excess clean steam is transported to the downstream evaporation and concentration section through the third steam pipeline, replacing expensive external energy.

[0029] (4) The bubble-free overflow discharge device of this utility model, through its internal "U"-shaped flow channel design, allows the tiny bubbles in the liquid sufficient time and space to rise due to buoyancy and separate from the mainstream liquid. Finally, what is discharged from the drain pipe is a pure, bubble-free single-phase liquid flow. This not only ensures accurate and reliable liquid level control, but also fundamentally eliminates the cavitation problem of downstream pumps, ensuring the long-term safe and stable operation of the entire production line. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of the present invention, form part of this invention. In the drawings:

[0031] Figure 1 This is a schematic diagram of the structure of the ammonium nitrate production neutralization system of this utility model;

[0032] Figure 2 This is a schematic diagram of the structure of the neutralizer of this utility model;

[0033] In the diagram: 1. Neutralizer; 2. Nitric acid pipeline; 3. Nitric acid storage tank; 4. Nitric acid preheater; 5. Ammonia pipeline; 6. Ammonia filter; 7. Ammonia preheater; 8. First steam pipeline; 9. Second steam pipeline; 10. Third steam pipeline; 11. Ammonia inlet; 12. Nitric acid inlet; 13. Gas distributor; 14. Perforated sieve plate; 15. Conical baffle; 16. Packing support plate; 17. Packing pressure plate; 18. Pall ring packing; 19. Lower manhole; 20. Upper manhole; 21. Demister; 22. Evaporated steam outlet; 23. Overflow weir box; 24. Overflow outer pipe; 2401. Feed inlet; 25. Guide pipe; 26. Drain pipe; 27. Discharge outlet; 28. Nitric acid spray head; 29. ​​Guide cylinder; 30. Drain outlet. Detailed Implementation

[0034] The present invention will be explained in detail below with reference to the embodiments.

[0035] Example 1

[0036] like Figure 1-2 As shown, the ammonium nitrate production neutralization system includes a neutralizer 1, and a nitric acid pipeline 2 and an ammonia pipeline 5 connected to the neutralizer 1. An ammonia filter 6 and an ammonia preheater 7 are sequentially installed on the ammonia pipeline 5. The ammonia pipeline 5 is connected to an ammonia inlet 11 in the middle of the neutralizer 1. A nitric acid storage tank 3 and a nitric acid preheater 4 are sequentially installed on the nitric acid pipeline 2. The neutralizer 1 has, from bottom to top, a reaction zone, a packing reaction separation zone, and a purification zone. A guide tube 29 is located at the lower center of the neutralizer 1. The guide tube 29 is fixed to the bottom of the neutralizer 1 by support legs, and its lower edge is flush with the bottom end cap of the neutralizer 1. A gap is left between the two. The top of the guide tube 29 is covered with a conical baffle 15. The top of the conical baffle 15 is open. After the ammonia pipeline 5 enters the interior of the neutralizer 1, it enters the interior of the guide tube 29 from the bottom side wall and connects to the upward-facing gas distributor 13. The nitric acid pipeline 2 enters the interior of the neutralizer 1 through the nitric acid inlet 12 and then enters the interior of the guide tube 29 from the bottom side wall and connects to the nitric acid spray head 28. The nitric acid spray head 28 is located above the gas distributor 13. The packing reaction separation zone is located above the conical baffle 15. The side wall of the neutralizer 1 is provided with a bubble-free overflow discharge device.

[0037] This system constructs a highly efficient air-lift internal circulation reactor. The guide tube 29 and its outer annular gap constitute the core circulation loop. The steam generated by the reaction generates a powerful air-lift force within the guide tube 29, driving the feed liquid to circulate at extremely high speeds in an "upper inside, lower outside" manner. This intense turbulence ensures uniform mixing of the acid and ammonia feedstocks, eliminating the possibility of localized over-acidity or over-alkaliness from the source, and achieving inherent safety in the process.

[0038] The packing reaction separation zone includes Pall ring packing 18 located above the conical baffle 15, and the Pall ring packing 18 is disposed between the packing support plate 16 and the packing pressure plate 17.

[0039] The purification zone is a demister 21 located above the packing plate 17, and the evaporation steam outlet 22 of the neutralizer 1 is located above the demister 21.

[0040] First, the high-speed gas-liquid flow impacts the conical baffle 15, changing its direction. Most droplets are thrown out and fall back due to inertia. The airflow passes through the Pall ring packing layer 18. On one hand, the Pall ring packing layer 18 can capture and neutralize trace amounts of unreacted ammonia that may escape from the gas phase, ensuring the purity of the discharged steam and preventing ammonia loss and corrosion of downstream equipment. On the other hand, it can also intercept and buffer any acidic droplets that may be entrained, stabilizing potential pH fluctuations through mixing with the bulk solution. Simultaneously, the thorough gas-liquid contact within the Pall ring packing layer 18 enhances heat transfer, resulting in a more uniform temperature distribution throughout the separation zone. Finally, the tiny droplets repeatedly collide, coalesce, grow, and fall back on the packing surface, achieving high capture efficiency and efficient secondary fine separation. The top demister 21 ultimately captures the escaped extremely fine droplets.

[0041] The bubble-free overflow discharge device includes an overflow weir box 23, which is located outside the neutralizer 1. The overflow weir box 23 extends to the bottom of the neutralizer 1 through a drain pipe 26 and leaves a gap with the bottom. A guide pipe 25 is sleeved on the drain pipe 26. There is a gap between the bottom and side wall of the drain pipe 26 and the guide pipe 25. An overflow outer pipe 24 is provided outside the guide pipe 25. The bottom of the overflow outer pipe 24 extends to the bottom of the neutralizer 1. An inlet 2401 is opened on the bottom side wall of the overflow outer pipe 24. The bottom of the overflow weir box 23 is a discharge port 27.

[0042] The upper edge of the overflow pipe 24 is higher than the upper edge of the guide pipe 25.

[0043] The U-shaped flow channel design inside the bubble-free overflow discharge device forces the product liquid to undergo a slow "rise-overflow-fall" flow process. During this process, the tiny bubbles in the liquid have ample time and space to rise due to buoyancy and separate from the mainstream liquid. Ultimately, what is discharged from the drain pipe 26 is a pure, bubble-free single-phase liquid flow. This not only ensures precise and reliable liquid level control but also fundamentally eliminates cavitation problems in downstream pumps, guaranteeing the long-term safe and stable operation of the entire production line.

[0044] The inner wall of the guide tube 29 is provided with several layers of perforated sieve plates 14.

[0045] The multi-layer perforated sieve plate 14 installed inside the guide tube 29 further shears the rising large bubbles into smaller bubbles, increasing the gas-liquid mass transfer area, making the reaction more complete and the cycle more stable.

[0046] The neutralizer 1 has an upper manhole 20 at its upper part, a lower manhole 19 at its lower part, and a discharge port 27 at its bottom.

[0047] The steam transport pipelines at the top of the overflow weir box 23 and the top of the neutralizer 1 are divided into three pipelines: the first steam pipeline 8 connected to the ammonia preheater 7, the second steam pipeline 9 connected to the nitric acid preheater 4, and the third steam pipeline 10 connected to the evaporator.

[0048] Thanks to the high-quality secondary steam, this system achieves a high degree of energy self-sufficiency and comprehensive utilization. Steam directly provides heat energy to the ammonia preheater 7 and nitric acid preheater 4 via the first steam pipeline 8 and the second steam pipeline 9, forming an internal energy cycle. Excess clean steam is transported to the downstream evaporation section via the third steam pipeline 10, replacing expensive external energy sources. This significantly reduces the plant's utility consumption and production costs, resulting in substantial economic benefits.

[0049] The liquid product at the bottom of the overflow weir box 23 is discharged to the evaporation and concentration section through the discharge port 27.

[0050] The bottom of the neutralizer 1 is also provided with a drain port 30 for material discharge when the device is running, stopped or in an emergency.

[0051] Working principle:

[0052] Ammonia gas is transported through ammonia pipeline 5 to ammonia filter 6 to remove any mechanical impurities such as rust and oil. The clean ammonia gas then enters ammonia preheater 7 and is heated to a predetermined temperature. At the same time, dilute nitric acid stored in nitric acid storage tank 3 is pumped through nitric acid pipeline 2 to nitric acid preheater 4 for similar heating.

[0053] The heat required by the ammonia preheater 7 and the nitric acid preheater 4 is mainly provided by the high-temperature secondary steam drawn from the top evaporation steam outlet 22 of the neutralizer 1, which is supplied through the first steam line 8 and the second steam line 9, respectively. This constitutes the internal energy recovery loop of the system. Excess secondary steam is sent to the evaporation concentration via the third steam line 10.

[0054] The two preheated raw materials are precisely metered and sent to neutralizer 1 for reaction.

[0055] Preheated ammonia gas enters the neutralizer through ammonia inlet 11 and is injected into the bottom of the guide tube 29 through the gas distributor 13 in a multi-hole spray pattern. Preheated dilute nitric acid is sprayed down through nitric acid inlet 12 from the nitric acid spray head 28 above. The two meet at the bottom of the guide tube 29, where a violent neutralization reaction occurs instantaneously, releasing a large amount of heat and heating the surrounding liquid to boiling, producing a large amount of steam.

[0056] These steam bubbles, acting as a lifting medium, significantly reduce the average density of the fluid inside the guide tube 29. Meanwhile, the annular space between the outer side of the guide tube and the inner wall of the neutralizer 1 contains less gas and has a higher density. This significant density difference creates a powerful hydrostatic driving force, propelling the low-density fluid inside the tube upwards at high speed, while the high-density fluid outside sinks and flows back into the tube through the annular gap at the bottom, forming an extremely powerful, self-forced internal circulation that requires no mechanical power. The four layers of perforated sieve plates 14 inside the tube act as a rectifying and bubble-breaking mechanism, making the rising airflow more uniform and shearing large bubbles into smaller ones, further enhancing mixing and heat transfer.

[0057] The gas-liquid mixture, rushing out at high speed from the top of the guide tube 29, first impacts the conical baffle 15, which is the first stage of inertial separation. The abrupt change in flow direction throws out most of the heavier droplets. Subsequently, the steam carrying fine droplets continues to rise and enters the packing layer composed of Pall ring packing 18, which is the second stage of packing collision separation. The steam travels through the complex surfaces and channels of the packing, and the droplets condense and grow due to repeated collisions with the packing surface, eventually falling back under gravity. Finally, the basically clean steam passes through the demister 21 located at the top, which is the third stage of wire mesh capture separation. A fine metal wire mesh captures the smallest droplets. After this three-stage deep processing, the secondary steam discharged from the evaporation steam outlet 22 becomes very pure and dry.

[0058] During stable operation of neutralizer 1, the liquid level is maintained at a certain height. A portion of the circulating ammonium nitrate solution enters the bubble-free overflow discharge device through the inlet 2401 at the bottom of the overflow pipe 24. The liquid first rises slowly within the annular space of the overflow pipe 24 and the guide pipe 25. After the liquid level overflows the upper edge of the guide pipe 25, it slowly descends within the annular space of the guide pipe 25 and the central drain pipe 26. In this U-shaped flow path, any entrained microbubbles, due to their rising velocity being greater than the falling velocity of the liquid, will flow upstream and escape from the top of the guide pipe 25, returning to the neutralizer's gas phase space. Finally, the pure, bubble-free liquid product flows from the bottom of the drain pipe 26 into the overflow weir box 23, and is discharged from the outlet 27 at the bottom of the overflow weir box 23 into the evaporation and concentration section.

Claims

1. A neutralization system for ammonium nitrate production, comprising a neutralizer (1), and a nitric acid pipeline (2) and an ammonia pipeline (5) connected to the neutralizer (1), characterized in that, An ammonia filter (6) and an ammonia preheater (7) are sequentially installed on the ammonia pipeline (5). The ammonia pipeline (5) is connected to the ammonia inlet (11) in the middle of the neutralizer (1). A nitric acid storage tank (3) and a nitric acid preheater (4) are sequentially installed on the nitric acid pipeline (2). The neutralizer (1) is provided with a reaction zone, a packing reaction separation zone and a purification zone from bottom to top. A guide tube (29) is provided at the center of the lower part of the neutralizer (1). The guide tube (29) is fixed to the bottom of the neutralizer (1) by a support leg. A gap is left between its lower edge and the bottom end cap of the neutralizer (1). A conical baffle (15) covers the top of the guide tube (29). The top opening of the conical baffle (15) allows the ammonia pipeline (5) to enter the neutralizer (1) and then enter the guide tube (29) from the bottom side wall of the guide tube (29), connecting to the upward-mounted gas distributor (13). The nitric acid pipeline (2) enters the neutralizer (1) through the nitric acid inlet (12) and then enters the guide tube (29) from the bottom side wall of the guide tube (29), connecting to the nitric acid spray head (28). The nitric acid spray head (28) is located above the gas distributor (13). The packing reaction separation zone is located above the conical baffle (15). The side wall of the neutralizer (1) is equipped with a bubble-free overflow discharge device.

2. The ammonium nitrate production neutralization system according to claim 1, characterized in that, The packing reaction separation zone includes a Pall ring packing (18) located above the conical baffle (15), the Pall ring packing (18) being disposed between the packing support plate (16) and the packing pressure plate (17).

3. The ammonium nitrate production neutralization system according to claim 2, characterized in that, The purification zone is a demister (21) set above the packing plate (17), and the evaporation steam outlet (22) of the neutralizer (1) is above the demister (21).

4. The ammonium nitrate production neutralization system according to claim 1, characterized in that, The bubble-free overflow discharge device includes an overflow weir box (23), which is located outside the neutralizer (1). The overflow weir box (23) extends to the bottom of the neutralizer (1) through a drain pipe (26) and leaves a gap with the bottom. A guide pipe (25) is provided on the drain pipe (26). There is a gap between the bottom and side wall of the drain pipe (26) and the guide pipe (25). An overflow outer pipe (24) is provided outside the guide pipe (25). The bottom of the overflow outer pipe (24) extends to the bottom of the neutralizer (1). An inlet (2401) is opened on the bottom side wall of the overflow outer pipe (24). The bottom of the overflow weir box (23) is the discharge port (27).

5. The ammonium nitrate production neutralization system according to claim 4, characterized in that, The upper edge of the overflow pipe (24) is higher than the upper edge of the guide pipe (25).

6. The ammonium nitrate production neutralization system according to claim 1, characterized in that, The inner wall of the guide tube (29) is provided with several layers of perforated sieve plates (14).

7. The ammonium nitrate production neutralization system according to claim 1, characterized in that, The neutralizer (1) has an upper manhole (20) at its upper part and a lower manhole (19) at its lower part.

8. The ammonium nitrate production neutralization system according to claim 4, characterized in that, The steam transport pipelines at the top of the overflow weir box (23) and the top of the neutralizer (1) are divided into three pipelines: the first steam pipeline (8) connected to the ammonia preheater (7), the second steam pipeline (9) connected to the nitric acid preheater (4), and the third steam pipeline (10) connected to the evaporator.

Images