Method and device for reducing volatilization of granular fertilizer and improving strength

Abstract

The present invention relates to a method and device for reducing volatilization of granular fertilizer and improving strength, which are suitable for granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer. The granular fertilizer is treated in a vacuum packaging manner, and packaging tail gas is collected and purified, thereby mitigating the problems of thermal decomposition volatilization, hardening, pulverization and the like of the granular fertilizer in the long-term storage process in a packaging bag, improving the strength of the granular fertilizer, reducing the fragile and pulverization characteristics of the granular fertilizer, and improving the long-term storage quality of a granular fertilizer product.

Description

A method and device for reducing volatilization of granular fertilizer and improving strength Technical Field

[0001] The invention belongs to the technical field of fertilizer packaging and storage, and particularly relates to a method and device for reducing volatilization of granular fertilizer and improving its strength. Background Art

[0002] Ammonia-based carbon capture technology reacts an ammonia absorbent with CO₂ in flue gas, producing ammonium bicarbonate as a byproduct. Granular ammonium bicarbonate can be produced by extruding or granulating ammonium bicarbonate with the addition of a modified additive. Ammonium bicarbonate can also be mixed with one or more phosphate or potash fertilizers and then extruded and granulated to produce ammonium bicarbonate-based compound fertilizers. Granular ammonium bicarbonate and ammonium bicarbonate-based compound fertilizers are important fertilizer products in my country's agricultural production. Compared with traditional organic amine processes, ammonia-based carbon capture technology can capture, store, and recycle CO₂ from flue gas emissions, which is of great significance for controlling and reducing greenhouse gas emissions and addressing the greenhouse effect and global warming.

[0003] Ammonium bicarbonate is unstable and readily decomposes into carbon dioxide, ammonia, and water at high temperatures. Complete decomposition is achieved at 60°C. It is also hygroscopic, and decomposition accelerates upon deliquescing. Currently, granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizers are typically packaged using conventional methods. These products experience significant volatilization, decomposition, and pulverization when exposed to heat, impacting fertilizer quality and preventing long-term storage. This hinders the widespread utilization of byproducts from ammonia-based carbon capture systems.

[0004] Patent CN210592820U reports a moisture-proof fertilizer packaging system for phosphate and compound fertilizers. The system comprises a sequentially connected slurry tank, a tubular reactor, a granulator, a dryer, a cooling device, and a vacuum packaging machine. The vacuum packaging machine is housed in a packaging chamber, which also houses a dehumidifier. After granulation and forming, the fertilizer is dried, sealed, cooled, and further dried before being packaged in a dedicated packaging chamber using the vacuum packaging machine, essentially shielding the fertilizer from air. This technology primarily addresses the hygroscopic deliquesce characteristics of phosphate and compound fertilizers. It does not address the volatilization and pulverization decomposition of granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizers during storage. Furthermore, it fails to address the adverse effects of the escape of volatile gases such as ammonia during packaging on the operating environment, which can easily cause secondary pollution.

[0005] Summary of the Invention

[0006] To solve the above problems, the present invention provides a method and device for reducing the volatilization of granular ammonium bicarbonate and ammonium bicarbonate-based compound fertilizers and improving their strength. The technical solution is as follows:

[0007] Granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer is transported from the granulation workshop to the processing workshop. The water content of the ammonium bicarbonate in the granular fertilizer is no more than 5%, preferably no more than 3.5%. The particle size of the granular fertilizer ranges from 1mm to 6mm, preferably 3mm to 5mm. The granular fertilizer is discharged from the hopper into airtight packaging bags placed on the operating table below. A weighing scale is installed below the operating table to accurately control the weight of the granular fertilizer in the bag. After weighing and discharging, the bag is moved under the vacuum system, and the bag opening is placed in the vacuum system's exhaust port. The vacuum system is set to the operating vacuum level, and the bag is evacuated by the built-in vacuum pump.

[0008] After vacuuming is complete, the packaging and sealing system seals the bags. The granular fertilizer bags are then removed from the workbench manually or mechanically. The processing workshop is equipped with a temperature and humidity control system, equipped with air conditioning and a dehumidifier, to precisely control operating temperature and humidity.

[0009] The main parameters of vacuum packaging are as follows:

[0010] (1) The operating vacuum degree is controlled at -50 kPa to -100 kPa (gauge pressure), preferably -80 to -100 kPa (gauge pressure), and more preferably -90 to -100 kPa (gauge pressure);

[0011] (2) The operating temperature is controlled to be 5°C to 35°C, preferably 10°C to 25°C, and more preferably 15°C to 25°C;

[0012] (3) The relative humidity of the operating environment is controlled to be below 70%, preferably below 60%.

[0013] The granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer treated by vacuum packaging should be stored in the vacuum packaging bag for not less than 4 hours, preferably not less than 12 hours, and more preferably not less than 24 hours to improve the strength of the granular fertilizer.

[0014] The exhaust ports of the vacuum system and packaging sealing system are sealed and connected to the exhaust gas treatment system through pipelines.

[0015] The tail gas treatment system includes a vacuum pump, a bubbling absorption tower, and a gas buffer tank can also be installed as needed. After the packaging tail gas is discharged, it is transported to the gas buffer tank by the vacuum pump. A butterfly valve is installed between the connecting pipes of the vacuum pump and the gas buffer tank, and the gas buffer tank is equipped with a pressure gauge to monitor the gas pressure in the tank. The rear of the gas buffer tank is connected to an exhaust pump via a connecting pipe, and a butterfly valve is installed between the connecting pipes. The exhaust pump is connected to the bubbling absorption tower, and a gas flow meter is installed in the connecting pipe between the exhaust pump and the bubbling absorption tower to control the gas flow rate and gas pressure entering the tower. The packaging tail gas is discharged into the bottom of the bubbling absorption tower by the exhaust pump. After reacting with the absorption liquid in the bubbling absorption tower, it is discharged to the outside atmosphere from the top of the bubbling absorption tower. A demisting area is installed at the top of the bubbling absorption tower to eliminate water vapor carried over during the bubbling reaction.

[0016] The packaging exhaust mainly consists of volatile components such as moisture, oxygen, and ammonia on the surface of the particles.

[0017] The method for reducing volatilization and increasing strength of granular fertilizers according to the present invention is carried out in a suitable apparatus, preferably an apparatus for reducing volatilization and increasing strength of granular fertilizers according to the present invention.

[0018] The bubbling absorber's absorption liquid comes from the ammonia scrubber in the ammonia-based carbon capture system. The absorption liquid primarily consists of NH3 and NH4HCO3, but can also be sourced from process water. The absorption liquid is delivered to the bubbling absorber via pipelines and a transfer pump. After the absorption process is complete, the absorption liquid is returned to the ammonia scrubber in the ammonia-based carbon capture system via pipelines and a scrubber pump.

[0019] The tail gas treatment system can also include a water ring vacuum pump. The packaged tail gas is extracted by the water ring vacuum pump, where gas-liquid contact removes contaminants such as ammonia. Process water is replenished through a water ring tank, and the outlet water is directly piped into the ammonia scrubber of the ammonia-based carbon capture system for purification.

[0020] The improvement in the strength of granular fertilizers is reflected by comparing the difference in the strength values ​​of granular fertilizers before and after treatment. The granular strength test method is as follows: The strength of granular fertilizers is determined with reference to the standard "Determination of Average Compressive Strength of Nitrophosphate Fertilizer Granules" (GB / T10516-2012). It is determined by a fully automatic granular strength instrument and a compression test is used to determine the strength of the granules. Untreated and treated granular fertilizers are placed in containers respectively, and a compressive force perpendicular to the surface of the granules is applied. The deformation and breaking force of the granules under a certain compressive force are measured, and the strength values ​​of the different granules to be tested are automatically read by the instrument.

[0021] The strength (Newton, N) of the granular fertilizer treated by the method and apparatus for reducing volatilization of granular fertilizer and increasing strength according to the present invention increases by at least 20%, preferably at least 25%, more preferably at least 35%, and most preferably at least 40%.

[0022] The reduction in volatile fertilizer granules is determined by testing their decomposition rate before and after treatment. The testing method is as follows: Granular fertilizer decomposition is measured gravimetrically. The decomposition of ammonium bicarbonate produces NH3, H2O, and CO2, resulting in a decrease in weight. A certain weight of vacuum-treated and unvacuum-treated granules is weighed, placed in a constant temperature (25°C) in an incubator for a specified period (30 days), and then removed and weighed again. The decomposition rate is the ratio of the reduced weight to the original weight.

[0023] The decomposition rate of the granular fertilizer treated according to the method and apparatus for reducing volatilization and increasing strength of granular fertilizer of the present invention remains substantially unchanged, preferably remains unchanged.

[0024] This application also relates to the following implementation plans:

[0025] 1. A method for reducing volatilization and improving the strength of granular fertilizers, characterized in that granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizers are processed in a vacuum packaging manner to reduce the oxygen concentration, humidity, and concentration of volatile components on the surface of the granules in the packaging bag, thereby reducing problems such as decomposition and volatilization, compaction, pulverization, and breakage during storage, transportation, and use, while simultaneously improving the strength and slow-release capacity of the granular fertilizers.

[0026] 2. The method as described in embodiment 1 is characterized in that a sealing packaging bag is used and a vacuum system is used to evacuate the packaging bag.

[0027] 3. The method according to embodiment 1, wherein the ammonium bicarbonate in the granular fertilizer comes from an ammonia carbon capture system.

[0028] 4. The method according to embodiment 1, wherein the water content of the ammonium bicarbonate in the granular fertilizer is not higher than 5%, preferably not higher than 3.5%.

[0029] 5. The method according to embodiment 1 is characterized in that the granular ammonium bicarbonate is formed by extrusion granulation of ammonium bicarbonate or ammonium bicarbonate with a modified auxiliary agent.

[0030] 6. The method according to embodiment 1 is characterized in that the ammonium bicarbonate-based compound fertilizer in the granular fertilizer is prepared by mixing ammonium bicarbonate with one or more of phosphate fertilizer, potash fertilizer, etc. and then extruding and granulating the mixture.

[0031] 7. The method according to embodiment 1 is characterized in that it also includes using an exhaust gas treatment system to remove volatile gas ammonia extracted during the packaging process.

[0032] 8. The method described in Embodiment 7 is characterized in that the tail gas treatment system uses a bubbling absorption liquid to remove volatile gas ammonia extracted during the packaging process through a bubbling absorption process.

[0033] 9. The method as described in Embodiment 7 is characterized in that the washing liquid of the bubbling absorption process in the tail gas treatment system is returned to the ammonia carbon capture system.

[0034] 10. The method according to embodiment 1 is characterized in that the granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer treated by vacuum packaging is stored at an ambient temperature less than or equal to 30°C, preferably less than or equal to 20°C.

[0035] 11. The method described in Embodiment 7 is characterized in that the exhaust gas treatment system includes a water ring vacuum pump, and the packaging exhaust gas is extracted by the water ring vacuum pump, while the volatile gas ammonia extracted during the packaging process is removed.

[0036] 12. The method according to embodiment 11 is characterized in that the water ring vacuum pump is replaced by process water, and the effluent is removed from the ammonia carbon capture system.

[0037] 13. The method described in Embodiment 2 is characterized in that the vacuum system includes a water ring vacuum pump, and the packaging exhaust gas is extracted by the water ring vacuum pump.

[0038] 14. The method according to embodiment 8 is characterized in that the bubbling absorption liquid is provided by a process water system.

[0039] 15. The method according to embodiment 1, wherein the volatile matter is moisture, oxygen, and ammonia on the surface of the granular fertilizer.

[0040] 16. A device for reducing volatilization of granular fertilizer and improving its strength, comprising:

[0041] (1) Vacuum system for vacuuming granular fertilizer;

[0042] (2) Packaging and sealing system, which seals the packaging bags with airtight performance;

[0043] (3) tail gas treatment system, used to treat the gas extracted during the operations of (1) and (2);

[0044] (4) Temperature and humidity control system, which controls the temperature and humidity of (1) and (2);

[0045] (1) and (2) are integrally sealed and connected to (3) through a pipeline.

[0046] 17. The device according to embodiment 16, characterized in that the tail gas treatment system includes

[0047] (1) A vacuum pump, used to extract the packaging exhaust gas from the vacuum packaging system;

[0048] (2) Bubble absorption tower, used to purify packaging exhaust gas.

[0049] 18. The device as described in embodiment 16 is characterized in that the exhaust gas treatment system includes a gas storage buffer tank for storing the packaging exhaust gas extracted from the vacuum packaging system.

[0050] 19. The device according to embodiment 16, wherein the temperature and humidity control system includes an air conditioner and a dehumidifier to control the temperature and humidity.

[0051] 20. The device as described in embodiment 17 is characterized in that the bubbling absorption tower operates intermittently, and the gas entering the tower comes from the packaged tail gas stored in the gas storage buffer tank.

[0052] 21. The device as described in embodiment 16 is characterized in that the bubbling absorption tower is connected to the ammonia carbon capture system, the absorption liquid of the bubbling absorption tower is provided by the ammonia carbon capture system, and after the absorption is completed, the absorption liquid returns to the ammonia carbon capture system.

[0053] 22. The device as described in Embodiment 17 is characterized in that the bubbling absorption tower is connected to the process water system and the ammonia carbon capture system, and the absorption liquid of the bubbling absorption tower is provided by the process water system. After the absorption is completed, the absorption liquid is returned to the ammonia carbon capture system.

[0054] 23. The device as described in Embodiment 16 is characterized in that the tail gas treatment system includes a water ring vacuum pump, which is connected to the process water system and the ammonia carbon capture system. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG1 is a schematic diagram of a technical solution according to the present invention,

[0056] FIG2 is a schematic diagram of a technical solution according to the present invention,

[0057] The reference numerals are as follows:

[0058] 1. Ammonia carbon capture system; 2. Granulation system; 3. Feeding system; 4. Packaging and sealing system; 5. Vacuum system; 6. Temperature and humidity control system; 7. Closed system; 8. Vacuum pump; 9. Gas storage buffer tank; 10. Treated granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer; 11. Bubbling absorption tower; 12. Washing pump; 13. Water ring vacuum pump; 14. Water ring tank; 15. Process water.

[0059] Example 1:

[0060] As shown in Figure 1, the ammonium bicarbonate product from the ammonia carbon capture system enters granulation system 2. The resulting ammonium bicarbonate-based compound fertilizer is processed by granulation system 2, controlling the water content of the ammonium bicarbonate in the granular fertilizer to no more than 3%. The particle size of the granular fertilizer ranges from 3mm to 5mm. The granular fertilizer enters feeding system 3, where it is discharged through a hopper into airtight bags placed on a workbench below. A weighing scale is installed below the workbench to precisely control the weight of the granular fertilizer in the bag. After weighing and discharging, the bag moves to packaging and sealing system 4. The bag opening is placed in the exhaust port of vacuum system 5. The vacuum level in vacuum system 5 is set, and the bag is evacuated by a built-in vacuum pump.

[0061] After vacuuming is complete, the packaging and sealing system 4 seals the bag. After sealing, the granular fertilizer 10 is manually or mechanically removed from the operating table within the bag. The device is equipped with a temperature and humidity control system 6, which includes an air conditioner and a dehumidifier to precisely control operating temperature and humidity.

[0062] The main parameters of vacuum packaging are as follows:

[0063] (1) The operating vacuum is controlled at -90 to -100 kPa (gauge pressure);

[0064] (2) The operating temperature is controlled at 15℃~25℃;

[0065] (3) The relative humidity of the operating environment is controlled below 60%.

[0066] The vacuum system 5 and the packaging and sealing system 4 are isolated by a closed system 7 and connected to the tail gas treatment system through a pipeline.

[0067] The tail gas treatment system includes a vacuum pump 8, a bubbling absorption tower 11, and a gas buffer tank 9. After the packaged tail gas is discharged, it is transported to the gas buffer tank 9 by the vacuum pump 8. A butterfly valve is provided between the connecting pipe between the vacuum pump and the gas buffer tank, and a pressure gauge is provided in the gas buffer tank to monitor the gas pressure in the tank. The rear part of the gas buffer tank is connected to the exhaust pump through a connecting pipe, and a butterfly valve is provided between the connecting pipes. The exhaust pump is connected to the bubbling absorption tower 11, and a gas flow meter is provided on the connecting pipe between the exhaust pump and the bubbling absorption tower to control the gas flow rate and gas pressure entering the tower. The packaged tail gas is discharged into the bottom of the bubbling absorption tower by the exhaust pump, and after an absorption reaction occurs with the absorption liquid in the bubbling absorption tower, it is discharged to the outside atmosphere from the top of the bubbling absorption tower. A demisting area is provided on the top of the bubbling absorption tower to eliminate water vapor carried during the bubbling reaction.

[0068] The bubbling absorber's absorption liquid comes from the ammonia scrubber in the ammonia-based carbon capture system. The absorption liquid, primarily composed of NH₃ and NH₄HCO₃, is delivered to the bubbling absorber via pipelines and a transfer pump. The absorption liquid can also be directly fed with process water. After the absorption process is complete, the absorption liquid is returned to the ammonia scrubber in the ammonia-based carbon capture system via pipelines and a scrubber pump.

[0069] Comparison of ammonium bicarbonate-based compound fertilizer granules before and after vacuum treatment:

[0070] Example 2:

[0071] As shown in Figure 2, the tail gas treatment system differs from that in Example 1 and includes a water ring vacuum pump 13, a water ring tank 14, and process water 15. Packaged tail gas is extracted by the water ring vacuum pump 13. The gas passing through the water ring vacuum pump undergoes gas-liquid contact within the water ring tank, removing contaminants such as ammonia and then being discharged from the top of the water ring tank to the atmosphere. Process water 15 is replenished through the water ring tank 14, and the effluent is directly piped into the ammonia scrubber of the ammonia-based carbon capture system 1 for purification.

[0072] The data of the comparison before and after vacuum treatment of the ammonium bicarbonate-based compound fertilizer particles in Example 2 are the same as those in Example 1.

[0073] It can be seen from the results of Examples 1 and 2 above that the strength of the granular fertilizer treated by the method and apparatus for reducing volatilization of granular fertilizer and improving strength of the present invention is significantly increased while the decomposition rate remains unchanged.

[0074] The above description is merely a preferred embodiment of the present invention. Those skilled in the art, once understanding the technical means of the present invention, will naturally be able to modify the present invention according to their actual needs. Therefore, all equivalent changes and modifications made within the scope of the present invention are still covered by the present invention.

Claims

1. A method for reducing the volatilization of granular chemical fertilizers and increasing their strength, characterized in that, The granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer is processed by vacuum packaging method to reduce the concentrations of components such as oxygen concentration, humidity, and volatile components on the surface of the granules in the packaging bag, reduce problems such as decomposition and volatilization, caking, pulverization, and breakage during storage, transportation, and use, and at the same time improve the strength and slow-release ability of the granular chemical fertilizer.

2. The method according to claim 1, characterized in that , Use a packaging bag with airtight performance, and the vacuum system evacuates the packaging bag.

3. The method according to claim 1, wherein , The ammonium bicarbonate in the granular chemical fertilizer comes from an ammonia-based carbon capture system.

4. The method according to claim 1, wherein , The water content in the ammonium bicarbonate of the granular chemical fertilizer is not higher than 5%, preferably not higher than 3.5%.

5. The method according to claim 1, wherein , The granular ammonium bicarbonate is formed by extrusion granulation of ammonium bicarbonate or ammonium bicarbonate added with a modifying agent.

6. The method according to claim 1, characterized in that , The ammonium bicarbonate-based compound fertilizer in the granular chemical fertilizer is formed by extrusion granulation after mixing ammonium bicarbonate with one or more of phosphate fertilizer, potassium fertilizer, etc.

7. The method according to claim 1, characterized in that , It also includes using an exhaust gas treatment system to remove the volatile gas ammonia extracted during the packaging process.

8. The method according to claim 7, wherein The exhaust gas treatment system removes the volatile gas ammonia extracted during the packaging process by using a bubbling absorption liquid through a bubbling absorption process.

9. The method according to claim 7, wherein The washing liquid of the bubbling absorption process in the exhaust gas treatment system returns to the ammonia-based carbon capture system.

10. The method according to claim 1, characterized in that, For the granular ammonium bicarbonate or ammonium bicarbonate-based compound fertilizer processed by the vacuum packaging method, the storage environmental temperature should be less than or equal to 30 °C, preferably less than or equal to 20 °C.

11. The method according to claim 7, wherein , The exhaust gas treatment system includes a water ring vacuum pump, and the packaging exhaust gas is extracted by the water ring vacuum pump, and at the same time, the volatile gas ammonia extracted during the packaging process is removed.

12. The method according to claim 11, wherein , The water ring vacuum pump is replenished and replaced with process water, and the effluent goes to the ammonia-based carbon capture system.

13. The method according to claim 2, wherein , The vacuum system includes a water ring vacuum pump, and the packaging exhaust gas is extracted by the water ring vacuum pump.

14. The method according to claim 8, wherein , The bubbling absorption liquid is provided by the process water system.

15. The method according to claim 1, characterized in that , The volatile components are the surface moisture, oxygen, and ammonia of the granular chemical fertilizer.

16. A device for reducing the volatilization of granular chemical fertilizers and increasing the strength, characterized in that , It includes: (1) A vacuum system for evacuating the granular chemical fertilizer; (2) A packaging sealing system for sealing the packaging bag with airtight performance; (3) An exhaust gas treatment system for treating the gas extracted during operations (1) and (2); (4) A temperature and humidity control system for controlling the temperature and humidity of (1) and (2); By integrally enclosing (1) and (2) and connecting them to (3) through pipelines.

17. The device according to claim 16, characterized in that, The exhaust gas treatment system includes (1) An air extraction pump for extracting the packaging exhaust gas from the vacuum packaging system; (2) A bubbling absorption tower for purifying the packaging exhaust gas.

18. The device according to claim 16, characterized in that, The exhaust gas treatment system includes a gas storage buffer tank for storing the packaging exhaust gas extracted from the vacuum packaging system.

19. The device according to claim 16, wherein The temperature and humidity control system includes an air conditioner and a dehumidifier to control the temperature and humidity.

20. The device according to claim 17, characterized in that, The bubbling absorption tower operates intermittently, and the inlet gas comes from the packaging exhaust gas stored in the gas storage buffer tank.

21. The device according to claim 16, characterized in that , The bubbling absorption tower is connected to the ammonia-based carbon capture system, and the absorption liquid of the bubbling absorption tower is provided by the ammonia-based carbon capture system. After absorption, the absorption liquid returns to the ammonia-based carbon capture system.

22. The device according to claim 17, wherein , The bubbling absorption tower is connected to the process water system and the ammonia-based carbon capture system. The absorption liquid of the bubbling absorption tower is provided by the process water system. After absorption, the absorption liquid returns to the ammonia-based carbon capture system.

23. The device according to claim 16, characterized in that , The exhaust gas treatment system includes a water ring vacuum pump, and the water ring vacuum pump is connected to the process water system and the ammonia-based carbon capture system.

Images