NPK compound fertilizer production line
By optimizing the equipment connections and exhaust gas treatment of the NPK compound fertilizer production line, the problems of complex drying and increased burden on tubular reactors due to washing liquid in compound fertilizer production have been solved, achieving efficient production of high-nutrient compound fertilizer and improving yield and product quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HUBEI EZHONG ECOLOGICAL AGRI TECH CO LTD
- Filing Date
- 2025-04-29
- Publication Date
- 2026-05-26
AI Technical Summary
Existing compound fertilizer production processes suffer from problems such as complex drying processes and increased washing liquid burden on tubular reactors, leading to reduced yields and difficulty in producing high-nutrient compound fertilizers.
An NPK compound fertilizer production line was designed, eliminating the drying structure. Through a tail gas treatment device and a hydrochloric acid recovery device, the connection between the reactor, mixed acid tank, tubular reactor and granulation device was optimized. A spray granulator and a drum cooler were adopted, combined with a tail gas treatment system consisting of a Venturi scrubber, a primary scrubbing tower and a secondary scrubbing tower, to reduce the amount of washing liquid entering the tubular reactor and improve the yield and nutrient content.
It enables the efficient production of high-nutrient (over 45%) compound fertilizer without the need for a drying structure, ensuring yield while reducing standard coal consumption and moisture content, and improving granulation qualification rate.
Smart Images
Figure CN224280113U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of compound fertilizer technology, and specifically relates to an NPK compound fertilizer production line. Background Technology
[0002] Compound fertilizers are chemical fertilizers containing two or more of the following nutrients: nitrogen, phosphorus, and potassium. They have advantages such as high nutrient content, fewer by-products, and good physical properties. They play a very important role in balanced fertilization, improving fertilizer utilization, and promoting high and stable crop yields.
[0003] like Figure 1 As shown, the existing compound fertilizer preparation method is as follows: concentrated sulfuric acid and potassium chloride react in a reactor to obtain potassium bisulfate, and the slurry is sent to a mixed acid tank; phosphoric acid is added to the mixed acid tank, and then the slurry is sent to a tubular reactor; ammonia gas is introduced into the tubular reactor, and the main reaction is the reaction between phosphoric acid and ammonia gas, and then the slurry is sent to a granulation device; in the granulation device, the slurry, return material, and urea (other raw materials may be added as needed, or not) are granulated to obtain granules; the granules are dried, sieved, cooled, and coated to obtain the product. The granulation tail gas, drying tail gas, and cooling tail gas are sent to a tail gas treatment device for treatment, and the washing liquid is sent to the tubular reactor for reuse.
[0004] For example, patent application number CN201910060089.3 discloses a new method for producing ammonium-sulfur-based compound fertilizer. The method includes the following steps: mixing ammonium phosphate and water to make ammonium phosphate slurry, and adding the resulting mixture to a mixed acid tank; mixing sulfuric acid and potassium chloride and performing low-temperature conversion, adding water to the generated HCl to produce hydrochloric acid, and adding the generated potassium bisulfate to the mixed acid tank; the slurry obtained after mixing the above materials in the mixed acid tank is fed into a tubular reactor, and ammonia is added to the tubular reactor; the material generated by the reaction of the slurry and ammonia in the tubular reactor is directly sprayed onto a granulation material bed; an ammonia shaft is provided in the granulation material bed, which passes ammonia and water vapor into the granulation material bed; external solidifying material is added to the granulation material bed; the granulated product of the granulation material bed is dried; after drying, it is sequentially screened, cooled, coated, and packaged, and the final product is directly shipped out of the factory.
[0005] For example, patent application number CN202010183294.1 discloses a production process for sulfur-based high-nitrogen compound fertilizer, including the following steps:
[0006] 1) Dechlorination is achieved by reacting potassium chloride and sulfuric acid in a reaction tank at low temperature.
[0007] 2) The hydrogen chloride gas produced in step 1 is reacted with potassium bisulfate. Hydrochloric acid is produced as a byproduct after the hydrogen chloride gas is absorbed.
[0008] 3) Add potassium bisulfate from step 2 into the mixed acid tank and add phosphoric acid to form mixed acid.
[0009] 4) The mixed acid and ammonia from step 3 are neutralized in a tubular reactor to form a finished slurry, which is then fed into the slurry tank.
[0010] 5) After heating and mixing urea and formaldehyde in a urea solution tank, the mixture is sent to a slurry tank for reaction and mixing.
[0011] 6) The total mixture slurry from step 6 is sent to a granulator for granulation, low-temperature drying, and granulation. After screening and coating, the compound fertilizer product is produced.
[0012] All of the above processes require a drying process.
[0013] In addition, in the prior art, in order to reduce the drying process, a large amount of concentrated sulfuric acid is used. For example, patent application number CN202310907973.2 discloses a method for preparing water-soluble sulfur-based compound fertilizer, which includes the following steps:
[0014] (1) In the reaction vessel, concentrated sulfuric acid and potassium chloride react under heating conditions at a temperature of 105-115℃ for 25-45 minutes. The slurry is then sent to a cooling vessel. The molar ratio of concentrated sulfuric acid to potassium chloride is 6.6-8.4:1.
[0015] (2) In the cooling kettle, the temperature is reduced to 40-60℃, and the slurry is sent to the acid mixing tank.
[0016] (3) In the mixed acid tank, add dilute phosphoric acid, potassium bisulfate solution and the slurry from step (2), the reaction temperature is 65-75℃, and the slurry is sent to the tubular reactor. The molar ratio of potassium bisulfate to potassium chloride is 0.5-1.0:1, and the molar ratio of phosphoric acid to potassium chloride is 0.9-1.3:1.
[0017] (4) In a tubular reactor, ammonia, washing liquid and slurry from step (3) are added. The reaction temperature is 150-180℃. The slurry is sent to a granulator. The amount of washing liquid is controlled to ensure that the reaction temperature is 150-180℃ and the density of the slurry after the reaction is less than 1.6 g / cm³. The molar ratio of ammonia to potassium chloride is 8-11:1.
[0018] (5) In the granulator, alkaline compound fertilizer raw materials, return material and slurry from step (4) are added for granulation. The granulation temperature is 80-95℃, the return material ratio is 1:1.5-2.0, and the amount of alkaline compound fertilizer raw materials needs to be controlled so that the pH of the product is 3.6-4.2. The alkaline compound fertilizer raw materials include ammonium carbonate or ammonium bicarbonate.
[0019] (6) The granules obtained from the granulator are cooled and screened to obtain the product. The screened material is returned to the granulator. The granulation and cooling exhaust gas is sent to the exhaust gas treatment structure for treatment. The washing liquid of the exhaust gas treatment structure is sent to the tubular reactor.
[0020] However, this method can only produce low-nutrient compound fertilizers, and the washing liquid increases the burden on the tubular reactor (a key component that limits production), thus reducing output. Utility Model Content
[0021] To address the aforementioned problems, this utility model provides an NPK compound fertilizer production line that eliminates the need for a drying structure and the need to send washing liquid to a tubular reactor, thus ensuring output. Furthermore, it can produce high-nutrient compound fertilizer. The technical solution is as follows:
[0022] This utility model provides an NPK compound fertilizer production line, which includes a tail gas treatment device, a hydrochloric acid recovery device, a reaction vessel 4, a mixed acid tank 5, a mixed acid storage tank 7, a tubular reactor 9, a slurry storage tank 11, a granulation device, a screening device, and a cooling device. The reaction vessel 4, the mixed acid tank 5, the mixed acid storage tank 7, and the tubular reactor 9 are connected sequentially by pipelines. The tail gas outlet of the reaction vessel 4 is connected to the hydrochloric acid recovery device by a pipeline. The tail gas outlets of the granulation device and the cooling device are both connected to the tail gas treatment device by pipelines. The production line also includes a flash tank 10. The tubular reactor 9, the flash tank 10, the slurry storage tank 11, and the granulation device are connected sequentially by pipelines. The granulation device, the screening device, and the cooling device are connected sequentially. The washing liquid outlet of the tail gas treatment device is connected to the inlet of the flash tank 10 by a pipeline. The tail gas outlet of the flash tank 10 is connected to the tail gas treatment device by a pipeline. The granulation device is a spray granulator, and the tubular reactor 9 is a pressure reactor.
[0023] The exhaust gas treatment device in this embodiment includes a Venturi scrubber 13, a primary scrubbing tower 14, a fan 15, a secondary scrubbing tower 16, and a chimney 17 connected sequentially from front to back. The exhaust gas outlets of the granulation device and the cooling device are connected to the Venturi scrubber 13 via pipelines. The Venturi scrubber 13 and the primary scrubbing tower 14 share a circulating scrubbing tank, which is connected to the inlet of the flash tank 10 via a pipeline with a pump. The water inlet of the secondary scrubbing tower 16 is connected to a process water storage tank or a clean water supply structure, and its washing liquid outlet overflows into the circulating scrubbing tank. The washing liquid outlet of the primary scrubbing tower 14 is connected to the inlet of the flash tank 10 via a pipeline, and the exhaust gas outlet of the flash tank 10 is connected to the air inlet of the secondary scrubbing tower 16 via a pipeline.
[0024] Furthermore, in this embodiment of the present invention, the secondary washing tower 16 is provided with a demister at the top, an upper spray structure in the upper part, a lower spray structure in the middle part, a first air inlet at the bottom, and a second air inlet at the top; the upper spray structure and the lower spray structure are both connected to the bottom of the secondary washing tower 16 through a pipeline with a second circulating pump, the first air inlet is connected to the fan 15 through a pipeline, and the second air inlet is connected to the exhaust gas outlet of the flash tank 10 through a pipeline.
[0025] Furthermore, the production line provided by this utility model also includes a potassium chloride silo 1, a sulfuric acid storage tank 2, a phosphoric acid storage tank 3, and an ammonia supply structure. The potassium chloride silo 1 is connected to the reactor 4 via a screw conveyor. The sulfuric acid storage tank 2 is connected to the reactor 4 via a pipeline with a metering pump. The phosphoric acid storage tank 3 is connected to the mixed acid tank 5 via a pipeline with a metering pump. The ammonia supply structure is connected to the tubular reactor 9 via a pipeline.
[0026] In this embodiment of the present invention, the reaction vessel 4, the mixed acid tank 5, the mixed acid storage tank 7, the flash evaporator 10, and the slurry storage tank 11 are all equipped with a stirrer, the reaction vessel 4 is equipped with a heater, and the walls of the mixed acid storage tank 7 and the slurry storage tank 11 are all equipped with a heat insulation layer.
[0027] Preferably, in this embodiment of the present invention, the reaction vessel 4 is a cylindrical structure, with an overflow baffle in the middle dividing it into a primary reaction tank and a secondary reaction tank; the potassium chloride silo 1 is connected to the primary reaction tank via a screw conveyor, and the sulfuric acid storage tank 2 is connected to the primary reaction tank via a pipeline with a metering pump; the slurry from the primary reaction tank overflows into the secondary reaction tank, and the secondary reaction tank is connected to the mixed acid tank 5 via a pipeline; both the primary and secondary reaction tanks are equipped with a stirrer and a heater, and the reaction temperature of the secondary reaction tank is lower than that of the primary reaction tank.
[0028] Specifically, in this embodiment of the present invention, the reaction vessel 4 is higher than the mixed acid tank 5. The mixed acid tank 5, the mixed acid storage tank 7, and the flash tank 10 are arranged side by side. The mixed acid tank 5 is connected to the mixed acid storage tank 7 through a pipeline with a first slurry pump 6. The mixed acid storage tank 7 is connected to the inlet of the tubular reactor 9 through a pipeline with a second slurry pump 8. The outlet of the tubular reactor 9 is connected to the flash tank 10 through a pipeline. The flash tank 10 is higher than the slurry storage tank 11, and its overflow port is connected to the slurry storage tank 11 through a pipeline. The slurry storage tank 11 is connected to the granulation device through a pipeline with a third slurry pump 12.
[0029] Specifically, in this embodiment of the present invention, the specifications of the reaction vessel 4 are: diameter 3000-4000mm * height 2000-4000mm; the specifications of the mixed acid tank 5 are: diameter 2000-3000mm * height 1500-2500mm; the specifications of the mixed acid storage tank 7 are: diameter 3000-4500mm * height 3000-5000mm; the specifications of the tubular reactor 9 are: diameter 350-550mm; the specifications of the flash tank 10 are: diameter 2500-3500mm * height 2500-3500mm; the specifications of the slurry storage tank 11 are: diameter 2500-3500mm * height 1500-2500mm; and the specifications of the granulation device are: diameter 4000-5000mm * height 20000-25000mm.
[0030] The beneficial effects of the technical solution provided by this utility model embodiment are as follows: This utility model embodiment provides an NPK compound fertilizer production line that does not require a drying structure or sending the washing liquid to a tubular reactor, thus ensuring output; in addition, it can produce high-nutrient (above 45%) compound fertilizer. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the existing compound fertilizer production line.
[0032] Figure 2 This is a schematic diagram of the NPK compound fertilizer production line provided in this embodiment of the utility model;
[0033] Figure 3 This is a structural diagram of a combination of potassium chloride silo, sulfuric acid storage tank, phosphoric acid storage tank, reaction vessel, mixed acid tank, mixed acid storage tank, tubular reactor, flash tank and slurry storage tank.
[0034] Figure 4 This is a structural diagram of a Venturi scrubber, a primary scrubbing tower, a fan, a secondary scrubbing tower, and a chimney.
[0035] In the diagram, 1 is a potassium chloride silo, 2 is a sulfuric acid storage tank, 3 is a phosphoric acid storage tank, 4 is a reaction vessel, 5 is a mixed acid tank, 6 is a first slurry pump, 7 is a mixed acid storage tank, 8 is a second slurry pump, 9 is a tubular reactor, 10 is a flash tank, 11 is a slurry storage tank, 12 is a third slurry pump, 13 is a Venturi scrubber, 14 is a primary scrubbing tower, 15 is a blower, 16 is a secondary scrubbing tower, and 17 is a chimney.
[0036] A. Hydrogen chloride tail gas, B. Ammonia gas, C. From the tail gas treatment unit, D. To the granulation unit, E. Granulation and cooling tail gas, F. From the flash tank, G. Process water or clean water, H. To the flash tank. Detailed Implementation
[0037] To make the objectives, technical solutions and advantages of this utility model clearer, the utility model will be described in further detail below with reference to the accompanying drawings.
[0038] Example 1
[0039] See Figure 2-4 Example 1 provides an NPK compound fertilizer production line, which includes a tail gas treatment device, a hydrochloric acid recovery device, a potassium chloride silo 1, a sulfuric acid storage tank 2, a phosphoric acid storage tank 3, an ammonia supply structure, a reaction vessel 4, a mixed acid tank 5, a mixed acid storage tank 7, a tubular reactor 9, a flash tank 10, a slurry storage tank 11, a granulation device, a screening device, and a cooling device. The reaction vessel 4, mixed acid tank 5, mixed acid storage tank 7, tubular reactor 9, flash tank 10, slurry storage tank 11, and granulation device are connected sequentially via pipelines. The potassium chloride silo 1 is connected to the reaction vessel 4 via a screw conveyor for quantitatively supplying potassium chloride. The sulfuric acid storage tank 2 is connected to the reaction vessel 4 via a pipeline with a metering pump for supplying concentrated sulfuric acid (concentration greater than or equal to 95 wt%). The phosphoric acid storage tank 3 is connected to the mixed acid tank 5 via a pipeline with a metering pump for supplying phosphoric acid (concentration greater than or equal to 20 wt%). The ammonia supply structure is connected to the tubular reactor 9 via pipeline for supplying ammonia. The tail gas outlet of reactor 4 is connected to a hydrochloric acid recovery device via pipeline for hydrochloric acid recovery. The granulation device, screening device, and cooling device are sequentially connected via a conveying structure (including conveyor belts, bucket elevators, chutes, or combinations thereof). The tail gas outlets of both the granulation device (which may have a cyclone dust collector or bag filter installed between it and the tail gas treatment device) and the cooling device are connected to the tail gas treatment device via pipeline. The washing liquid outlet of the tail gas treatment device is connected to the inlet of flash tank 10 via pipeline, and the tail gas outlet of flash tank 10 is connected to the tail gas treatment device via pipeline. The granulation device is a spray granulator; the hot air temperature of the granulation device is 650-700℃ (higher than existing technology), and the temperature at its nozzle is 78-84℃ (slightly higher than existing technology). The tubular reactor 9 is a pressure reactor with a reaction pressure of 0.5-0.7 MPa, and the cooling device is a drum cooler.
[0040] Among them, see Figure 4The exhaust gas treatment device in this embodiment includes a Venturi scrubber 13, a primary scrubbing tower 14, a fan 15, a secondary scrubbing tower 16, and a chimney 17, connected sequentially from front to back. The exhaust gas outlets of the granulation device and the cooling device are both connected to the Venturi scrubber 13 via pipelines. The Venturi scrubber 13 and the primary scrubbing tower 14 share a circulating scrubbing tank. The circulating scrubbing tank is located below the Venturi scrubber 13 and the primary scrubbing tower 14. It is connected to the inlet of the flash tank 10 via a pipeline with a pump (outputting after a certain density or pH value), and it is connected to the nozzles inside the Venturi scrubber 13 and the primary scrubbing tower 14 via the pipeline of the first circulating pump. The water inlet of the secondary scrubbing tower 16 is connected to a process water storage tank or a clean water supply structure, and its washing liquid outlet overflows into the circulating scrubbing tank (circulated spraying multiple times, outputting after a certain density or pH value). The washing liquid outlet of the primary scrubbing tower 14 is connected to the inlet of the flash tank 10 via a pipeline, and the exhaust gas outlet of the flash tank 10 is connected to the air inlet of the secondary scrubbing tower 16 via a pipeline.
[0041] Among them, see Figure 3 In this embodiment of the present invention, the reactor 4, the mixed acid tank 5, the mixed acid storage tank 7, the flash evaporator 10 and the slurry storage tank 11 are all equipped with a stirrer, the reactor 4 is equipped with a heater (specifically a steam heater), and the mixed acid storage tank 7 and the slurry storage tank 11 are all equipped with a heat insulation layer on their tank walls.
[0042] The prepared compound fertilizer has a total nutrient content of ≥45%, a chlorine content of ≤1.8%, a moisture content of ≤1.5%, a standard coal consumption of 0.064t / t compound fertilizer (a reduction of more than 7% compared with existing technologies), and a granulation qualification rate of greater than 80%.
[0043] Example 2
[0044] See Figure 3 Example 2 provides an NPK compound fertilizer production line, whose structure is basically the same as that of Example 1, except that: in this embodiment, the reaction vessel 4 is higher than the mixed acid tank 5. The mixed acid tank 5, the mixed acid storage tank 7, and the flash tank 10 are arranged side by side and all located on the ground. The mixed acid tank 5 is connected to the mixed acid storage tank 7 through a pipeline with a first slurry pump 6. The mixed acid storage tank 7 is connected to the inlet of the tubular reactor 9 through a pipeline with a second slurry pump 8. The outlet of the tubular reactor 9 is connected to the flash tank 10 through a pipeline. The flash tank 10 is higher than the slurry storage tank 11 (which is a ground tank), and its overflow port is connected to the slurry storage tank 11 through a pipeline. The slurry storage tank 11 is connected to the granulation device through a pipeline with a third slurry pump 12.
[0045] Example 3
[0046] See Figure 4Example 3 provides an NPK compound fertilizer production line, whose structure is basically the same as that of Example 1, except that: the secondary washing tower 16 in this embodiment is equipped with a demister (specifically a wire mesh demister) at the top, an upper spray structure in the upper part, a lower spray structure in the middle part, a first air inlet at the bottom, and a second air inlet at the top (located between the upper and lower spray structures). Both the upper and lower spray structures are connected to the bottom of the secondary washing tower 16 through pipelines with a second circulating pump. The first air inlet is connected to the blower 15 through a pipeline, and the second air inlet is connected to the exhaust outlet of the flash tank 10 through a pipeline.
[0047] Example 4
[0048] See Figure 3 Example 4 provides an NPK compound fertilizer production line, whose structure is basically the same as that of Example 1, except that: the reaction vessel 4 in this embodiment is a cylindrical structure, with an overflow baffle in the middle dividing it into a primary reaction tank and a secondary reaction tank. The bottom of the overflow baffle is fixed to the bottom of the reaction vessel 4, and its top has a gap with the top of the reaction vessel 4. The potassium chloride silo 1 is connected to the primary reaction tank via a screw conveyor, and the sulfuric acid storage tank 2 is connected to the primary reaction tank via a pipeline with a metering pump. The slurry from the primary reaction tank overflows into the secondary reaction tank, which is connected to the mixed acid tank 5 via a pipeline. Both the primary and secondary reaction tanks are equipped with a stirrer and a heater. The reaction temperature of the secondary reaction tank (reaction temperature is 128-135℃) is lower than that of the primary reaction tank (reaction temperature is 105-110℃).
[0049] Example 5
[0050] Example 5 provides an NPK compound fertilizer production line, whose structure is basically the same as that of Example 1, except that: the specifications of the reaction vessel 4 in this embodiment are: diameter 3000-4000mm * height 2000-4000mm. The specifications of the mixed acid tank 5 are: diameter 2000-3000mm * height 1500-2500mm. The specifications of the mixed acid storage tank 7 are: diameter 3000-4500mm * height 3000-5000mm. The specifications of the tubular reactor 9 are: diameter 350-550mm. The specifications of the flash tank 10 are: diameter 2500-3500mm * height 2500-3500mm. The specifications of the slurry storage tank 11 are: diameter 2500-3500mm * height 1500-2500mm. The specifications of the granulation device are: diameter 4000-5000mm * height 20000-25000mm.
[0051] In this patent, the terms "first," "second," and "third" serve only as distinctions and have no other special meaning. The pipeline in this patent may be equipped with pumps, valves, or flow meters as needed.
[0052] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. An NPK compound fertilizer production line, comprising a tail gas treatment device, a hydrochloric acid recovery device, a reaction vessel (4), a mixed acid tank (5), a mixed acid storage tank (7), a tubular reactor (9), a slurry storage tank (11), a granulation device, a screening device, and a cooling device, wherein the reaction vessel (4), the mixed acid tank (5), the mixed acid storage tank (7), and the tubular reactor (9) are connected sequentially by pipelines, the tail gas outlet of the reaction vessel (4) is connected to the hydrochloric acid recovery device by a pipeline, and the tail gas outlets of the granulation device and the cooling device are both connected to the tail gas treatment device by pipelines; characterized in that, The production line also includes a flash tank (10). The tubular reactor (9), flash tank (10), slurry storage tank (11) and granulation device are connected in sequence by pipelines. The granulation device, screening device and cooling device are connected in sequence. The washing liquid outlet of the tail gas treatment device is connected to the inlet of the flash tank (10) by pipelines. The tail gas outlet of the flash tank (10) is connected to the tail gas treatment device by pipelines. The granulation device is a spray granulator. The tubular reactor (9) is a pressurized reactor.
2. The NPK compound fertilizer production line according to claim 1, characterized in that, The exhaust gas treatment device includes a Venturi scrubber (13), a primary scrubbing tower (14), a blower (15), a secondary scrubbing tower (16), and a chimney (17) connected in sequence from front to back. The exhaust gas outlets of the granulation device and the cooling device are connected to the Venturi scrubber (13) through pipelines. The Venturi scrubber (13) and the primary scrubbing tower (14) share a circulating scrubbing tank. The circulating scrubbing tank is connected to the inlet of the flash tank (10) through a pipeline with a pump. The water inlet of the secondary scrubbing tower (16) is connected to a process water storage tank or a clean water supply structure, and its washing liquid outlet overflows into the circulating scrubbing tank. The exhaust gas outlet of the flash tank (10) is connected to the air inlet of the secondary scrubbing tower (16) through a pipeline.
3. The NPK compound fertilizer production line according to claim 2, characterized in that, The secondary scrubbing tower (16) is equipped with a demister at the top, an upper spray structure in the upper part, a lower spray structure in the middle part, a first air inlet at the bottom, and a second air inlet at the top. The upper and lower spray structures are connected to the bottom of the secondary scrubbing tower (16) through a pipeline with a second circulating pump. The first air inlet is connected to the fan (15) through a pipeline, and the second air inlet is connected to the exhaust outlet of the flash tank (10) through a pipeline.
4. The NPK compound fertilizer production line according to claim 2, characterized in that, The production line also includes a potassium chloride silo (1), a sulfuric acid storage tank (2), a phosphoric acid storage tank (3), and an ammonia supply structure. The potassium chloride silo (1) is connected to the reactor (4) via a screw conveyor. The sulfuric acid storage tank (2) is connected to the reactor (4) via a pipeline with a metering pump. The phosphoric acid storage tank (3) is connected to the mixed acid tank (5) via a pipeline with a metering pump. The ammonia supply structure is connected to the tubular reactor (9) via a pipeline.
5. The NPK compound fertilizer production line according to claim 2, characterized in that, Agitators are provided in the reactor (4), mixed acid tank (5), mixed acid storage tank (7), flash tank (10) and slurry storage tank (11). A heater is provided in the reactor (4). Insulation layers are provided on the walls of the mixed acid storage tank (7) and the slurry storage tank (11).
6. The NPK compound fertilizer production line according to claim 4, characterized in that, The reactor (4) is a cylindrical structure with an overflow baffle in the middle, which divides it into a primary reaction tank and a secondary reaction tank. The potassium chloride silo (1) is connected to the primary reaction tank via a screw conveyor. The sulfuric acid storage tank (2) is connected to the primary reaction tank via a pipeline with a metering pump. The slurry from the primary reaction tank overflows into the secondary reaction tank. The secondary reaction tank is connected to the mixed acid tank (5) via a pipeline. Both the primary and secondary reaction tanks are equipped with a stirrer and a heater. The reaction temperature of the secondary reaction tank is lower than that of the primary reaction tank.
7. The NPK compound fertilizer production line according to claim 1, characterized in that, The reaction vessel (4) is higher than the mixed acid tank (5). The mixed acid tank (5), the mixed acid storage tank (7), and the flash tank (10) are arranged side by side. The mixed acid tank (5) is connected to the mixed acid storage tank (7) through a pipeline with a first slurry pump (6). The mixed acid storage tank (7) is connected to the inlet of the tubular reactor (9) through a pipeline with a second slurry pump (8). The outlet of the tubular reactor (9) is connected to the flash tank (10) through a pipeline. The flash tank (10) is higher than the slurry storage tank (11). The overflow port in the middle of the flash tank is connected to the slurry storage tank (11) through a pipeline. The slurry storage tank (11) is connected to the granulation device through a pipeline with a third slurry pump (12).
8. The NPK compound fertilizer production line according to claim 1, characterized in that, The specifications of the reactor (4) are: diameter 3000-4000mm * height 2000-4000mm; the specifications of the mixed acid tank (5) are: diameter 2000-3000mm * height 1500-2500mm; the specifications of the mixed acid storage tank (7) are: diameter 3000-4500mm * height 3000-5000mm; the specifications of the tubular reactor (9) are: diameter 350-550mm; the specifications of the flash tank (10) are: diameter 2500-3500mm * height 2500-3500mm; the specifications of the slurry storage tank (11) are: diameter 2500-3500mm * height 1500-2500mm; the specifications of the granulation device are: diameter 4000-5000mm * height 20000-25000mm.