Dap production apparatus and dap production method
By introducing a pre-neutralization tank, reactor, and ammonia adder into the DAP production unit, and using multiple ammonia addition pipes to perform multi-point ammonia addition within the granulator, the problem of insufficient amino acid reaction was solved, thereby improving the yield and quality of DAP.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KEYON PROCESS CO LTD
- Filing Date
- 2024-12-04
- Publication Date
- 2026-06-05
AI Technical Summary
In the current DAP production process, the amino acid reaction is insufficient, resulting in poor granulation effect and low yield.
A pre-neutralization tank, reactor, and ammonia adder are introduced into the DAP production unit. Ammonia is added at multiple points in the granulator through multiple ammonia addition pipes to ensure that the slurry and ammonia react fully to form DAP.
It improved the yield of DAP produced by the granulator, achieved a more efficient amino acid reaction, reduced ammonia escape and energy consumption, and improved product quality.
Smart Images
Figure CN122141568A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical technology, and in particular to a DAP production apparatus and a DAP production method. Background Technology
[0002] DAP (diammonium hydrogen phosphate) is the world's most widely used phosphate (P) fertilizer. It is made from two of the most common components in the fertilizer industry and is widely used due to its relatively high nutrient content and excellent physical properties. Ammonium phosphate fertilizers were first used in the 1960s, and DAP quickly became the most popular product of its kind. It is produced by a controlled reaction of phosphoric acid and ammonia to form a hot slurry, which is then cooled, granulated, and sieved.
[0003] Currently, the most common DAP production equipment and methods in existing technologies include the following:
[0004] 1. Traditional spray granulation process: This process is characterized by an integrated granulation and drying machine with a short process flow; the produced granules have a smooth surface and high hardness; there is no secondary ammonia replenishment point, it can only produce DAP products with a content of 57%, the amount of ammonia escaping from the tail gas is small; the temperature of the drying tail gas is low, at 60-70℃.
[0005] 2. The rotary drum ammoniation process using a pre-neutralization tank is characterized by the need for a phosphoric acid concentration of 40%-45% (w(P2O5)) in the pre-neutralization tank to obtain a slurry with good flowability that is easy to pump. Therefore, the product drying energy consumption is high, and the amount of return material required for granulation is large. Secondary ammonia addition can be made within the granulator to achieve a superior product (nitrogen content above 17%). The dryer outlet temperature reaches 90-100 degrees Celsius, and the ammonia escape rate from the granulator is large.
[0006] 3. Rotary drum ammoniation process using a tubular reactor: This process is characterized by the reaction being completed within a tubular reactor, with the reaction slurry directly sprayed onto the material bed inside the granulator. The tubular reactor can be single or double. It features a short reaction time, high heat of reaction (reaction temperature 130-150℃), and rapid evaporation of moisture from the material. A return ratio below 2 is sufficient for granulation, resulting in a low drying load. Secondary ammonia addition within the granulator can achieve superior quality (nitrogen content above 17%). The dryer outlet temperature reaches 80-90 degrees Celsius. The slurry has low moisture content, resulting in a less round product appearance, relatively small particle size, increased load on dust removal equipment, and high heat of reaction leading to significant ammonia release.
[0007] Both the pre-neutralization tank method and the tubular reactor method of rotary drum ammoniation process have the problem of insufficient amino acid reaction after the slurry enters the granulator, resulting in poor granulation effect and low yield. Summary of the Invention
[0008] The technical problem to be solved by the present invention is to overcome the defects in the existing technology that the amino acid reaction cannot be further adjusted in the DAP production process, resulting in poor granulation effect and low yield. The present invention provides a DAP production device and a DAP production method.
[0009] The present invention solves the above-mentioned technical problems through the following technical solution:
[0010] A DAP production apparatus includes: a pre-neutralization tank, a granulator, a reactor, and an ammonia adder;
[0011] The outlet of the pre-neutralization tank is connected to the granulator. The pre-neutralization tank is used for the reaction of the first phosphoric acid with ammonia to produce the first slurry.
[0012] The reactor outlet is connected to the granulator. The reactor is used for the reaction of the second phosphoric acid with ammonia to produce an amino acid, thereby generating a second slurry.
[0013] The ammonia feeder is connected to the granulator, and the ammonia gas, the first slurry, and the second slurry in the ammonia feeder all enter the granulator bed to react and form DAP.
[0014] In this scheme, both the pre-neutralization tank and the reactor are used to generate an amino acid reaction to produce a slurry. The slurry then reacts with ammonia in the ammonia feeder in the granulator to further regulate the amino acid reaction, making the amino acid reaction more complete and improving the yield of DAP produced by the granulator.
[0015] Preferably, the ammonia adder includes multiple ammonia adder pipes that enter the interior of the granulator from the head and / or tail of the granulator.
[0016] In this design, the use of multiple ammonia dosing pipes increases the amount of ammonia added to the granulator. Furthermore, the multiple pipes enter the granulator from both the head and / or tail, ensuring that the slurry from both the head and tail reacts with the ammonia in the pipes, further improving the yield of DAP produced by the granulator. Additionally, the increased contact points between the material bed and the ammonia facilitate efficient mass transfer (mass transfer is the process by which substances in a system move from one point to another under the influence of forces such as concentration difference, temperature difference, pressure difference, and potential difference), enabling rapid operation and control, and reducing the impact of defective DAP from the tail end on the production unit.
[0017] Preferably, multiple ammonia addition pipes are evenly spaced from the tail end of the granulator to the head end of the granulator.
[0018] In this scheme, the ammonia addition pipes are evenly spaced from the tail end of the granulator to the head end, which is conducive to the uniform and sufficient reaction of the slurry in the granulator with the ammonia gas in the ammonia addition pipes, thereby further improving the yield of DAP produced by the granulator.
[0019] Preferably, the ammonia addition pipe includes an inlet and an outlet. The inlet is located outside the granulator and is used to discharge ammonia gas; the outlet is located inside the granulator and is inserted into the material bed.
[0020] In this design, the way the ammonia addition pipe is set in the granulator is beneficial for both the discharge of ammonia into the granulator and the direct and sufficient contact between the ammonia and the material bed, resulting in faster and more efficient material production. In addition, the addition of ammonia at multiple points allows for the adjustment of the temperature and liquid phase of the material on the material bed to achieve optimal granulation conditions. In other words, adding ammonia at multiple points helps to improve the granulation effect.
[0021] Preferably, the DAP production apparatus further includes a slurry pump for pumping a first slurry into the bed of materials.
[0022] In this scheme, the slurry pump is designed to facilitate the rapid and uniform application of the first slurry into the material bed.
[0023] Preferably, the reactor includes a reaction tube, the first end of which is located outside the granulator and is used to introduce the second phosphoric acid to react with ammonia to produce amino acids; the second end of the reaction tube is located inside the granulator and is used to transport the second slurry to the bed.
[0024] In this scheme, the arrangement of the reaction tubes is beneficial for operating the amino acid reaction and for conveying the second slurry to the bed.
[0025] Preferably, the first phosphoric acid comprises 42% phosphorus pentoxide and the second phosphoric acid comprises 52% phosphorus pentoxide.
[0026] In this scheme, the phosphorus pentoxide content in the primary and secondary phosphoric acids is beneficial to improving the granulation effect of DAP.
[0027] Preferably, the DAP production apparatus further includes a dryer, a cooler, a wrapping machine, and a packaging machine;
[0028] The dryer's inlet is connected to the granulator and is used to dry the DAP from the granulator. The dryer's outlet is connected to the cooler, and the cooler, coating machine, and packaging machine are connected in sequence.
[0029] In this solution, the aforementioned dryer, cooler, coating machine, and packaging machine further optimize the DAP produced by the granulator to improve the quality of the DAP.
[0030] Preferably, the DAP production unit further includes an elevator, a return hopper, and a screening system; the screening system includes a flat screen and a finished product screen.
[0031] The flat screen, cooler, finished product screen, and coating machine are connected in sequence;
[0032] The elevator is connected to the dryer and is used to send the dried DAP to the flat screen. The flat screen is used to separate the finished product and non-finished product of DAP. The finished product enters the cooler. The finished product screen is used to further screen the cooled finished product and send it to the coating machine. The non-finished product enters the granulator through the return hopper.
[0033] In this design, the elevator facilitates the smooth and rapid delivery of DAP to the flat screen for further processing; the screening system removes non-conforming products from the DAP; and the return hopper helps to recover non-conforming products, acting as a buffer to provide a stable flow of return material to the granulator for continued DAP production.
[0034] The present invention also provides a DAP production method, which uses the above-described DAP production apparatus for production.
[0035] In this scheme, the DAP production method using the aforementioned DAP production equipment is beneficial for producing high-quality DAP.
[0036] The positive and progressive effects of this invention are as follows: In this DAP production device, both the pre-neutralization tank and the reactor are used to initiate an amino acid reaction to produce a slurry; the slurry then reacts with ammonia gas in the ammonia feeder in the granulator to further regulate the amino acid reaction, making the reaction more complete and improving the yield of DAP produced by the granulator. This DAP production method has the same effects as described above. This invention combines the advantages and disadvantages of existing processes and develops a pre-neutralization + tubular reactor + multi-tube ammoniation process. This process fully utilizes the advantages of pre-neutralization, tubular reactor, and rotary drum ammoniation, taking the best of both worlds and compensating for their shortcomings to ensure optimal granulation conditions within the granulator.
[0037] The purpose of this invention is to utilize the advantages of existing DAP production processes, and through in-depth development, create optimal granulation conditions to achieve a return ratio of less than 2, maintain product roundness, keep the dryer tail temperature below 90°C, reduce ammonia escape, and achieve energy saving, emission reduction, and convenient operation. Attached Figure Description
[0038] Figure 1 This is a schematic diagram of the structure of a DAP production apparatus according to an embodiment of the present invention.
[0039] Figure 2 for Figure 1 A partially enlarged structural diagram.
[0040] Explanation of reference numerals in the attached figures:
[0041] DAP production unit 100
[0042] Pre-neutralization tank 110
[0043] 120 Granulator
[0044] Material bed 121
[0045] Nose 122
[0046] Tail 123
[0047] Reaction tube 130
[0048] Ammonia addition tube 140
[0049] 150 slurry pump
[0050] Dryer 160
[0051] Cooler 170
[0052] 180 wrapping machine
[0053] 200 hoist
[0054] Return material bin 210
[0055] 220 flat screen
[0056] Finished product sieve 230
[0057] 240 return strip
[0058] Metering belt 250
[0059] Exhaust gas treatment system 260
[0060] Crusher 270
[0061] Dust removal system 280 Detailed Implementation
[0062] The present invention will be described more clearly and completely below with reference to the accompanying drawings, but this invention is not limited to the scope of this embodiment.
[0063] like Figures 1 to 2 As shown, this embodiment provides a DAP production apparatus 100, which includes: a pre-neutralization tank 110, a granulator 120, a reactor, and an ammonia feeder; the outlet of the pre-neutralization tank 110 is connected to the granulator 120, and the pre-neutralization tank 110 is used for the reaction of a first phosphoric acid with ammonia to produce an amino acid to generate a first slurry; the outlet of the reactor is connected to the granulator 120, and the reactor is used for the reaction of a second phosphoric acid with ammonia to produce a second slurry; the ammonia feeder is connected to the granulator 120, and the ammonia, the first slurry, and the second slurry in the ammonia feeder all enter the bed 121 of the granulator 120 to react and form DAP.
[0064] In this embodiment, both the pre-neutralization tank 110 and the reactor are used to generate an amino acid reaction to produce a slurry. The slurry then reacts with ammonia in the ammonia feeder in the granulator 120 to further regulate the amino acid reaction and improve the yield of DAP produced by the granulator 120.
[0065] It should be noted that DAP is granulated in granulator 120 to form DAP. During the operation of granulator 120, exhaust gas is generated. This exhaust gas enters the exhaust gas treatment system 260, which is connected to granulator 120, for treatment. The exhaust gas treatment system 260 is also connected to pre-neutralization tank 110. The exhaust gas generated by the amino acid reaction in pre-neutralization tank 110 also enters the exhaust gas treatment system 260 for treatment. In addition, the degree of neutralization of the amino acid reaction between the first phosphate and ammonia is in the range of 1.35-1.55, and the degree of neutralization of the amino acid reaction between the second phosphate and ammonia is in the range of 1.6-1.7. The exhaust gas generated by the amino acid reaction between the first phosphate and ammonia directly enters the exhaust gas treatment system 260, and the exhaust gas generated by the amino acid reaction between the second phosphate and ammonia enters the exhaust gas treatment system 260 through granulator 120.
[0066] refer to Figure 1 and Figure 2 It is understood that the ammonia adder includes multiple ammonia adder pipes 140, which enter the interior of the granulator 120 from the head 122 and / or tail 123 of the granulator 120.
[0067] In this embodiment, the arrangement of multiple ammonia addition pipes 140 can increase the amount of ammonia added to the granulator 120. Furthermore, the multiple ammonia addition pipes 140 enter the interior of the granulator 120 from the head 122 and / or tail 123, meaning the ammonia addition pipes 140 can enter the interior of the granulator 120 from any position within the head 122 and / or tail 123. This arrangement facilitates the reaction of the slurry from both the head 122 and tail 123 of the granulator 120 with the ammonia in the ammonia addition pipes 140, further improving the yield of DAP produced by the granulator 120. In addition, the increased contact points between the material bed 121 and the ammonia facilitate sufficient mass transfer (mass transfer is the process by which substances in a system move from one place to another under the driving force of concentration difference, temperature difference, pressure difference, potential difference, etc.), enabling rapid operation control and reducing the impact of substandard DAP generated at the tail 123 on the production unit.
[0068] It should be noted that multiple ammonia addition pipes 140 enter the material bed 121 at different positions inside the granulator 120. The diameter of the ammonia addition pipe should not be too large, and the pipe head inserted into the material bed 121 should form an angle of 30-45 degrees with the vertical direction.
[0069] refer to Figure 1 and Figure 2It should be understood that multiple ammonia addition pipes 140 are evenly spaced from the tail 123 of the granulator 120 to the head 122 of the granulator 120. Here, "evenly spaced" means that the interval between two adjacent ammonia addition pipes 140 is the same.
[0070] In this embodiment, the ammonia addition pipe 140 is evenly spaced from the tail 123 of the granulator 120 to the head 122 of the granulator 120, which is conducive to the uniform and sufficient reaction of the slurry in the granulator 120 with the ammonia in the ammonia addition pipe 140, thereby further improving the yield of DAP produced by the granulator 120.
[0071] It should be noted that in this embodiment, the first ammonia charging pipe 140 is set at a position 2.4 meters from the tail of the machine, the second ammonia charging pipe 140 is set at a interval of 400 mm, and the last ammonia charging pipe 140 is 2.6 meters from the head of the machine. The ammonia charging pipe 140 is a seamless steel pipe with an outer diameter of 32 mm and a wall thickness of 3.5 mm. In addition, the number of ammonia charging pipes 140 can be adjusted according to the required DAP production scale.
[0072] refer to Figure 1 and Figure 2 It is understood that the ammonia addition pipe 140 includes an inlet and an outlet. The inlet is located outside the granulator 120 and is used to discharge ammonia gas. The outlet is located inside the granulator 120 and is inserted into the material bed 121.
[0073] In this embodiment, the way the ammonia addition pipe 140 is set in the granulator 120 is not only conducive to the discharge of ammonia into the granulator 120, but also conducive to the direct and sufficient contact between the ammonia and the material bed 121, resulting in faster and more efficient material production. In addition, the addition of ammonia at multiple points allows for the adjustment of the temperature and liquid phase of the material on the material bed 121 to achieve optimal granulation conditions. In other words, adding ammonia at multiple points is beneficial to improving the granulation effect.
[0074] It should be noted that the outlet pipe opening is flat, and the gap width is 5-8mm.
[0075] refer to Figure 1 and Figure 2 It is understood that the DAP production unit 100 also includes a slurry pump 150, which is used to pump a first slurry into the bed 121.
[0076] In this embodiment, the slurry pump 150 is provided to facilitate the rapid and uniform application of the first slurry into the material bed 121.
[0077] It should be noted that the slurry pump 150 is located between the pre-neutralization tank 110; furthermore, the slurry pump 150 is only a preferred structural configuration, and in other embodiments, other structural configurations that can realize the pumping of slurry can also be selected.
[0078] refer to Figure 1 and Figure 2 It is understood that the reactor includes a reaction tube 130, the first end of which is located outside the granulator 120 and is used to introduce the second phosphoric acid to react with ammonia to produce amino acids; the second end of the reaction tube 130 is located inside the granulator 120 and is used to transport the second slurry to the bed 121.
[0079] In this embodiment, the arrangement of the reaction tube 130 is beneficial for operating the amino acid reaction and for conveying the second slurry to the bed 121.
[0080] It should be noted that multiple reaction tubes 130 can be set according to the required DAP production scale, and the ammonia in the reaction tube 130 does not originate from the aforementioned ammonia addition tube 140; in addition, the tail gas in the granulator 120 enters the tail gas treatment system 260 through the air duct for tail gas treatment.
[0081] refer to Figure 1 and Figure 2 It should be understood that the primary phosphoric acid contains 42% phosphorus pentoxide and the secondary phosphoric acid contains 52% phosphorus pentoxide.
[0082] In this embodiment, the phosphorus pentoxide content in the first and second phosphoric acids is beneficial to improving the DAP granulation effect.
[0083] refer to Figure 1 and Figure 2 It is understood that the DAP production unit 100 also includes a dryer 160, a cooler 170, a wrapping machine 180, and a packaging machine.
[0084] The inlet of the dryer 160 is connected to the granulator 120 and is used to dry the DAP from the granulator 120. The outlet of the dryer 160 is connected to the cooler 170. The cooler 170, the coating machine 180 and the packaging machine are connected in sequence.
[0085] In this embodiment, the dryer 160, cooler 170, coating machine 180 and packaging machine are configured to further optimize the DAP produced by the granulator 120, so as to improve the quality of DAP.
[0086] It should be noted that the dryer 160 is also connected to the hot air furnace. The DAP in the dryer 160 is dried in parallel with the hot air from the hot air furnace. The exhaust gas generated in the dryer 160 enters the exhaust gas treatment system 260 for treatment. When the moisture content of DAP is 3-4% and the temperature is 70-80℃, it enters the dryer 160 from the granulator 120.
[0087] refer to Figure 1 and Figure 2It is understood that the DAP production unit 100 also includes an elevator 200, a return hopper 210, and a screening system; the screening system includes a flat screen 220 and a finished product screen 230.
[0088] The flat screen 220, cooler 170, finished product screen 230 and coating machine 180 are connected in sequence.
[0089] The elevator 200 is connected to the dryer 160 and is used to send the dried DAP to the flat screen 220. The flat screen 220 is used to separate the finished product and non-finished product of DAP. The finished product enters the cooler 170. The finished product screen 230 is used to further screen the cooled finished product and send it to the coating machine 180. The non-finished product enters the granulator 120 through the return hopper 210.
[0090] In this embodiment, the elevator 200 facilitates the smooth and rapid delivery of DAP to the flat screen 220 for the next step of operation; the screening system can discharge non-finished products that do not meet the specifications in the DAP; the return hopper 210 facilitates the recovery of non-finished products, acts as a buffer, and provides a stable flow of return material to the granulator for continued DAP production.
[0091] It should be noted that the flat screen 220 transports the large DAP particles after screening to the crusher 270 for crushing, and then returns them to the return hopper 210 via the return belt 240. The exhaust gas generated in the crusher 270 enters the dust removal system 280, and the small particles also return directly to the return hopper 210 via the return belt 240. The return material from the return hopper 210 is metered by the metering belt 250 and then enters the granulator 120. In addition, the flat screen 220 is also connected to the cooler 170. The finished product after screening (the finished product here is of standard size) DAP particles enter the cooler 170 for cooling. The finished product temperature drops to below 45°C. After cooling, the particles go to the finished product screen 230. The cooled exhaust gas enters the dust removal system 280. The finished product screen 230 filters out the small amount of powder generated when DAP is transported from the flat screen 220 to the finished product screen 230 (i.e., the powder generated by the friction between DAP and itself during the above process, as well as the powder generated by the collision between DAP and the flat screen 220, the cooler 170, and the finished product screen 230). The powder is returned to the return hopper 210 via the return belt 240.
[0092] As is well known, the reaction between ammonia and acid is mainly controlled by the mass transfer rate. As long as the two reactants can be mixed rapidly, the reaction can be completed immediately. At the same time, any method that can enhance the mass transfer rate between ammonia and acid can accelerate the neutralization reaction process. The key to DAP production is to achieve optimal granulation conditions through a reasonable amino acid reaction method, which is convenient to operate and easy to produce.
[0093] There are three granulation mechanisms in the rotary drum ammoniating granulator: coating granulation, agglomeration, and self-granulation. To maintain particle size balance within the granulator 120, it is generally desirable for material granulation to be primarily coating granulation, supplemented by an appropriate proportion of self-granulation, while avoiding agglomeration granulation as much as possible, because agglomerated granules have poor quality and their particle size is difficult to control. However, when the particle size balance within the granulator 120 is already lost (e.g., too much fine powder, resulting in undersized product particles), appropriately increasing the proportion of agglomeration granulation can be used as a means to adjust the particle size balance within the granulator 120. From the perspective of particle size balance, all process controls in granulation and drying involve adjusting the relevant process parameters to change the relative proportions of these three granulation mechanisms. Suitable material temperature and liquid phase quantity in the granulator 120's bed 121 are key process conditions for granulation.
[0094] This invention revolves around granulation. Building upon the large-scale amino acid reaction in a pre-neutralization (PN) + tubular reaction (PR) mixing process, it further regulates the amino acid reaction by employing multi-point ammonia addition instead of single-point ammonia addition. This allows for precise control of two key parameters affecting the granulation process: material temperature and liquid phase quantity in bed 121. While adjusting the degree of neutralization, the focus is on finely regulating the material temperature and liquid phase quantity in bed 121, controlling the optimal point where temperature and liquid phase quantity are matched. This adjustment method is convenient and flexible. (See also...) Figure 2 A schematic location of the ammonia addition point within the granulator 120 of an embodiment of the present invention.
[0095] from Figure 2 As can be seen, ammoniation inlet points are located at both the head (122) and tail (123) of granulator 120, employing a multi-pipe ammonia inlet system. The number of inlet pipes on the feed bed is adjusted according to the production scale. Taking a 200,000-ton / year DAP production line as an example, the first ammonia inlet pipe is placed 2.4 meters from the discharge port of tail (123), followed by a second pipe at a 400-mm interval, and so on towards the head (122), with the last pipe 2.6 meters from the head. The ammonia inlet pipes are seamless steel pipes with an outer diameter of 32mm and a wall thickness of 3.5mm. The pipe opening at the end extending into the feed bed (121) is flat, with a gap width of 5-8mm. The increased contact points between the feed bed (121) and ammonia facilitate sufficient mass transfer, rapid operation control, and reduces the impact of substandard material from tail (123) on the production system, resulting in stable granulation. The diameter of the ammonia addition pipe should not be too large, and the pipe head inserted into the material bed 121 should form an angle of 30-45° with the vertical direction.
[0096] The pre-neutralization (PN) + tubular reactor (PR) amino acid reaction process has been applied to multiple production lines. Compared to the pre-neutralization (PN) process, this process has the advantages of reducing return material and maximizing the utilization of reaction heat; compared to the tubular reactor process, it has the advantages of lowering the slurry temperature and reducing ammonia escape. Currently, this process can achieve two granulation indexes: a material temperature of 70℃-90℃ and a liquid phase content of 6%-9%. However, in operation, the material temperature and liquid phase content must be constantly monitored and controlled to achieve the optimal point. The pre-neutralization + tubular reactor mixed process is not flexible in controlling the optimal points of material temperature and liquid phase content at any time. Fine adjustments are slow to take effect, and even slight adjustments can lead to large fluctuations in the granulation layer, which is not conducive to production stability. If there is no multi-point ammonia addition process in the granulator 120, when the material condition in the material bed 121 of the granulator 120 changes, the on-site personnel cannot adjust the material condition in the granulator 120 immediately. Unqualified materials in the entire granulator 120 will enter the drying process, causing subsequent system disorder. If the material is mostly powdery, it will increase the load on the fine material screen in the screening process, causing fine powder and small particles to be entrained in the finished product screen area. The drying exhaust gas will also carry a large amount of dust, increasing the load and potentially causing the system to shut down. If the material is mostly large particles, the crushing capacity of the crusher will increase. When it exceeds the crushing capacity, the crusher will stop working, clogging the system.
[0097] In this embodiment, the DAP production apparatus employs a multi-ammonia-adding process. Ammonia is added at the head 122 and tail 123 of the granulator 120 for ammoniation, ensuring uniform ammoniation throughout the material bed 121 of the granulator 120. This allows for fine-tuning of the material bed in the pre-neutralization tank 110 combined with the reactor process, maintaining the material bed 121 in optimal granulation conditions at all times. The goal is to ensure that the material exiting the granulator 120 meets the requirement that no more than 5% of the particles have a diameter greater than 4mm, and no more than 10% have a diameter less than 2mm.
[0098] By constantly observing the material condition through the granulator 120, when the particles in the granulator 120 are small, or when the DAP specific surface area is large and the temperature of the bed 121 is close to the upper limit of 90°C, it indicates that the temperature is high, the moisture evaporates quickly, and there is no fine powder coating on the particle surface. At this time, the amount of ammonia added should be appropriately reduced, the reaction temperature should be slightly lowered, and the moisture evaporation should be reduced. When the particles are small and the temperature of the bed 121 is close to the lower limit of 70°C, it indicates that the temperature is low and the liquid phase is insufficient. At this time, the amount of ammonia added should be increased to raise the temperature of the bed 121 through the reaction and increase the liquid phase.
[0099] Many factors influence particle size balance within the granulator 120, making control complex. Particle size control is generally not a single-factor adjustment but a multi-factor adjustment. The DAP production device in this embodiment, based on the pre-neutralization tank 110 and a reactor, adds multiple ammonia addition pipes 140 to the granulation process, providing a more flexible and rapid adjustment method. Fine-tuning the granulation state through multiple ammonia addition pipes 140 achieves a more reasonable granulation effect. The following key steps must be followed:
[0100] A: The temperature and moisture content of the returned material remain stable, and the material flow into the granulator at 120 remains stable;
[0101] B: The concentration and flow rate of the first slurry in the pre-neutralization tank 110 are stable, and the degree of neutralization is stable between 1.35 and 1.55;
[0102] C: The neutralization degree of the second slurry in the reactor is 1.6-1.7. By adjusting the amount of tail wash liquid added, the temperature of the second slurry does not exceed 150℃.
[0103] D: The first and second slurries entering the granulator 120 are evenly sprayed onto the material bed 121;
[0104] E: The particle size distribution of the returned material entering granulator 120 is as follows: the proportion of particles larger than 4.0mm and smaller than 1.0mm shall not exceed 5.0%; the proportion of particles larger than 4.0mm shall be less than 5%; the proportion of particles between 2.8-4.0mm shall be between 30%-40%; the proportion of particles between 2.0-2.8mm shall be between 30%-40%; and the proportion of particles smaller than 2.0mm shall be less than 20%.
[0105] The production process of DAP production unit 100 is described in detail below.
[0106] The first slurry generated by the reaction of first phosphoric acid and ammonia in the pre-neutralization tank 110 is fed into the granulator bed 121 of the granulator 120 by the slurry pump 150. The second slurry generated by the reaction of second phosphoric acid and ammonia in the reactor is fed into the granulator bed 121 of the granulator 120.
[0107] The tail gas generated in the pre-neutralization tank 110 enters the tail gas treatment system 260, and the tail gas generated in the reactor enters the tail gas treatment system 260 through the granulator 120.
[0108] The ammonia gas in the ammonia adder enters the granulator 120 through the ammonia adder pipe 140 to further adjust the state of the first slurry and the second slurry to form DAP. Therefore, the tail gas generated in the granulator 120 also enters the tail gas treatment system 260.
[0109] The aforementioned DAP enters the dryer 160 for drying, and the exhaust gas generated by the dryer 160 also enters the exhaust gas treatment system 260.
[0110] After drying, DAP enters a flat screen 220 to separate finished and non-finished products. Non-finished products include large and small DAP particles. The particle size of large DAP particles is larger than that of the finished product, while the particle size of small DAP particles is smaller than that of the finished product. Large DAP particles are transported to a crusher 270 for crushing and then returned to a return hopper 210 via a return conveyor belt 240. Small DAP particles also return directly to the return hopper 210 via the return conveyor belt 240. The finished product is cooled by a cooler 170 and then enters a finished product screen 230 for further screening (to remove powder generated by friction between DAP particles during the above process, as well as powder generated by collisions between DAP particles and the flat screen 220, cooler 170, and finished product screen 230). It then enters a coating machine 180. In addition, during the above DAP production process, the exhaust gas generated by the flat screen 220, crusher 270, and cooler 170 during operation is treated by a dust removal system 280 and then discharged by a fan.
[0111] This embodiment also provides a DAP production method, which uses the DAP production apparatus 100 described above for production.
[0112] In this embodiment, the DAP production method using the DAP production apparatus 100 described above is beneficial for producing high-quality DAP.
[0113] The DAP production method includes the following steps:
[0114] In the pre-neutralization tank, the first phosphoric acid and ammonia are reacted to produce an amino acid to generate the first slurry;
[0115] In the reactor, the second phosphoric acid reacts with ammonia to produce an amino acid, thereby generating a second slurry;
[0116] In granulator 120, the first and second slurries are reacted with ammonia to form amino acids, thereby forming DAP.
[0117] In summary, the present invention provides a DAP production apparatus 100 and a DAP production method. The slurry of the DAP production apparatus 100 reacts again with ammonia gas in the ammonia adder in the granulator 120 to further regulate the above-mentioned amino acid reaction and improve the yield of DAP produced by the granulator 120.
[0118] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship of the device or element during normal use. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation at any time, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention in this respect.
[0119] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.
Claims
1. A DAP production apparatus, characterized in that, The DAP production unit includes: a pre-neutralization tank, a granulator, a reactor, and an ammonia adder; The outlet of the pre-neutralization tank is connected to the granulator. The pre-neutralization tank is used for the reaction of the first phosphoric acid with ammonia to produce an amino acid to generate a first slurry. The reactor outlet is connected to the granulator, and the reactor is used for the reaction of second phosphoric acid with ammonia to produce a second slurry; The ammonia feeder is connected to the granulator, and the ammonia gas, the first slurry, and the second slurry in the ammonia feeder all enter the bed of the granulator to react and form DAP.
2. The DAP production apparatus according to claim 1, characterized in that, The ammonia adder includes multiple ammonia adder pipes, which enter the interior of the granulator from the head and / or tail of the granulator.
3. The DAP production apparatus according to claim 2, characterized in that, The multiple ammonia addition pipes are evenly spaced from the tail end of the granulator to the head end of the granulator.
4. The DAP production apparatus according to claim 2, characterized in that, The ammonia addition pipe includes an inlet and an outlet. The inlet is located outside the granulator and is used to discharge ammonia gas. The outlet is located inside the granulator and is inserted into the material bed.
5. The DAP production apparatus according to claim 1, characterized in that, The DAP production apparatus also includes a slurry pump, which is used to pump the first slurry into the bed of materials.
6. The DAP production apparatus according to claim 1, characterized in that, The reactor includes a reaction tube, the first end of which is located outside the granulator and is used to introduce the second phosphoric acid to react with the ammonia gas to produce amino acids; the second end of which is located inside the granulator and is used to transport the second slurry into the bed.
7. The DAP production apparatus according to claim 1, characterized in that, The first phosphoric acid comprises 42% phosphorus pentoxide, and the second phosphoric acid comprises 52% phosphorus pentoxide.
8. The DAP production apparatus according to claim 1, characterized in that, The DAP production unit also includes a dryer, a cooler, a coating machine, and a packaging machine; The dryer's inlet is connected to the granulator and is used to dry the DAP from the granulator. The dryer's outlet is connected to the cooler. The cooler, the coating machine, and the packaging machine are connected in sequence.
9. The DAP production apparatus according to claim 8, characterized in that, The DAP production unit also includes an elevator, a return hopper, and a screening system; the screening system includes a flat screen and a finished product screen. The flat screen, the cooler, the finished product screen, and the coating machine are connected in sequence; The elevator is connected to the dryer and is used to send the dried DAP to the flat screen. The flat screen is used to separate the finished product and non-finished product of the DAP. The finished product enters the cooler. The finished product screen is used to further screen the cooled finished product into the coating machine. The non-finished product enters the granulator through the return hopper.
10. A DAP production method, characterized in that, It is produced using any one of the DAP production devices described in 1-9 above.