CN-121972079-A - System for fertilizer production and application method thereof

CN121972079ACN 121972079 ACN121972079 ACN 121972079ACN-121972079-A

Abstract

The invention belongs to the technical field of fertilizer production equipment, and particularly discloses a system for fertilizer production and a using method thereof. The system comprises a fluidization and spraying subsystem, a feeding subsystem, an external temperature control subsystem and an intelligent control and on-line monitoring subsystem, wherein the core of the system is a fluidized bed with an expansion section, a barrel section and a conical bottom cylinder, the fluidized bed is integrated with fertilizer granulation and coating processes through a multi-region gas distribution part, a layered spraying module and a zonal temperature control design, the integrated continuous production of self-disintegrating functional fertilizers is realized by combining with the integrated design of other systems, the problems of process cutting, low efficiency and poor product consistency in multilayer structure fertilizer production are solved, the integrity of self-disintegrating fertilizer granule gas-producing cores, the uniformity and consistency of the thickness of each functional layer and the stability of disintegrating performance among batches are ensured, and the span from laboratory formulas to large-scale stable production is realized.

Inventors

XU CHENGLONG
LI XIAOXIAO
XIE BIHAI
ZHANG HANLIN
LV WEIGUANG
LI SHUANGXI
SONG KE
ZHANG HAIYUN
ZHANG YUE
Zhu Xianpu

Assignees

上海市农业科学院

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (12)

1. A fluidized bed for preparing a multi-layered structured fertilizer, characterized in that the fertilizer comprises a gas-generating inner core, a fertilizer carrier layer and a controlled release coating layer from inside to outside, the fluidized bed (21) comprising: a housing (211) comprising an enlarged section (2111), a barrel section (2112) and a conical bottom cylinder (2113) from top to bottom; The inlet and outlet comprises a gas phase outlet (216) arranged at the top of the expansion section (2111), a feed inlet (217) arranged on the outer wall of the cylinder section (2112) and used for inputting a gas producing core micro-core, and a discharge outlet (218) and a gas phase inlet (219) arranged at the bottom of the conical bottom cylinder (2113); The spraying module (213) is arranged in the cylinder section (2112) and is positioned below the feeding hole (217), the module at least comprises an upper group of nozzles and a lower group of nozzles, a plurality of nozzles are circumferentially arranged in each group, the lower group of nozzles are used for spraying fertilizer slurry and adhesive, and the upper group of nozzles are used for spraying coating liquid; A multi-zone gas distribution member (212) disposed inside the conical bottom cylinder (2113) and above the gas phase inlet (219) for obtaining a uniform and stable fluidization state for the upper particulate material by differential air supply; The temperature control component comprises a jacket (214) wound on the outer wall of the cylinder section (2112) and an infrared heating component arranged on the expansion section (2111), wherein heating gas is input through a gas phase inlet (219), heat conduction oil is introduced into the jacket (214), and the infrared heating component is started to respectively form a bottom air inlet preheating zone, a cylinder fluidization reaction zone and a top coating drying zone in a fluidized bed.
2. The fluidized bed according to claim 1, wherein the multi-zone gas distribution unit (212) comprises a gas supply chamber (2124), a second orifice plate (2123), a flow guiding cavity (2122) and a first orifice plate (2121) from bottom to top, the gas supply chamber (2124) is provided with an annular partition plate for dividing the gas supply chamber into a central zone (2124 a) and an annular gap zone (2124 b), the central zone (2124 a) and the annular gap zone (2124 b) are respectively connected with gas inlet pipes (2125), differential air supply is realized by controlling the inlet flow rates of the two gas inlet pipes (2125), and the aperture of the first orifice plate (2121) is smaller than that of the second orifice plate (2123).
3. The fluidized bed according to claim 1, wherein the spraying module (213) comprises three groups of nozzles for spraying fertilizer slurry and adhesive, switching between spraying different functional slurries and spraying coating liquid from bottom to top, wherein the upper layer of nozzles adopts two precise fan-shaped nozzles, the middle layer of nozzles adopts two air atomizing nozzles, and the bottom layer of nozzles adopts four wide-angle solid cone-shaped nozzles.
4. The fluidized bed according to claim 1, wherein a gas one-way valve (220) is arranged at the gas phase inlet (219), and a temperature sensing probe (215) is arranged on the top inner wall of the conical bottom cylinder (2113).
5. A system for fertilizer production, comprising: A fluidization and spray subsystem (2) comprising a fluidized bed according to any one of claims 1 to 4 and a tail gas treatment unit for treating the gas phase outlet (216) exhaust of the fluidized bed; a feed subsystem (1) comprising a core feed unit, a slurry feed unit and a coating liquid feed unit for providing each layer of raw materials of fertilizer to the fluidized bed; and the external temperature control subsystem (3) is used for adjusting the air inlet temperature of the gas phase inlet (219) of the fluidized bed.
6. The system for fertilizer production according to claim 5, characterized in that the tail gas treatment unit comprises a cyclone (22) and a bag filter (23) connected in sequence, the inlet of the cyclone (22) being connected with the gas phase outlet (216) of the fluidized bed.
7. The system for fertilizer production according to claim 5, characterized in that the inner core feed unit comprises a vacuum feeder (11), a weightless type feeding scale (12), a screw feeder (13) connected in sequence, the outlet of the screw feeder (13) being connected with the feed inlet (217) of the fluidized bed; the slurry supply unit comprises a plurality of batching tanks (14) which are independently used for preparing fertilizer slurry, adhesive solution or standby cleaning solvent, and a diaphragm pump (15) which is connected with the batching tanks (14) and the fluidized bed nozzle; The coating liquid feeding unit comprises a liquid storage tank (16) and a peristaltic pump (17) connected with the liquid storage tank (16) and the fluidized bed nozzle.
8. The system for fertilizer production according to claim 5, characterized in that the external temperature control subsystem (3) comprises a blower (31), an air heater (32), an air compressor (33) connected in sequence, the outlet of the air compressor (33) being connected with the gas phase inlet (219) of the fluidized bed.
9. The system for fertilizer production of claim 5, further comprising an intelligent control and on-line monitoring subsystem (4), the intelligent control and on-line monitoring subsystem (4) comprising a machine vision unit, an on-line weigh feedback unit and a central controller (41), the machine vision unit being a high resolution industrial camera and high speed image processing system mounted at a viewing window, the on-line weigh feedback unit being a high precision load cell disposed under the fluidized bed for real time monitoring of bed weight changes.
10. A method of producing fertilizer using the system of any one of claims 5-9, comprising the steps of: S1, initializing a system, namely starting the system to raise each temperature zone in the fluidized bed to a set temperature through an internal temperature control component and an external temperature control subsystem (3); s2, core fluidization and fertilizer carrier layer granulation, namely, feeding the gas-producing core micro-cores into a fluidized bed feed inlet (217) through a core feed unit, starting a bottom layer nozzle after fluidization is stable, and alternately spraying an adhesive and fertilizer slurry which are conveyed to the bottom layer nozzle by a slurry feed unit according to a preset program for granulation; s3, switching to an upper nozzle, and spraying the coating liquid conveyed to a top nozzle by a coating liquid feeding unit to the surface of the particles; S4, drying and discharging, namely after coating is finished, maintaining fluidization, heating up and drying, and finally conveying finished product particles to a cooling and screening working section through a bottom discharging hole (218).
11. The method according to claim 10, wherein in the step S1, the fluidization air quantity is set to be 0.3-0.5m/S, and the set temperature of each temperature zone is as follows, the temperature of the bottom inlet preheating zone is 45 ℃, the temperature of the barrel fluidization reaction zone is 45+/-2 ℃, and the temperature of the top coating drying zone is 35+/-2 ℃; and/or in the step S2, the diameter of the gas producing inner core micro-core is 1.0-1.5mm, the feeding rate of the gas producing inner core micro-core is 0.5-5.0kg/h, the atomization pressure is 0.2-0.4 MPa, the droplet size Dv50 is controlled to be 80-120 mu m, and the spraying rate of the adhesive and the fertilizer slurry is 1.5L/h until the particle size grows to 3-5mm; And/or, in the step S3, the coating liquid is sprayed on the surface of the particles by the upper nozzle at a constant speed of 0.8L/h.
12. The method of claim 10, wherein the fluidized bed gas phase outlet (216) exhaust gas from the fertilizer production process is dedusted by a tail gas treatment unit and solvent vapor is condensed.

Description

System for fertilizer production and application method thereof Technical Field The invention belongs to the technical field of fertilizer production equipment, and particularly relates to a fluidized bed coating system for preparing a multilayer-structure fertilizer, which is particularly suitable for producing self-disintegrating functional fertilizer particles consisting of a gas-producing inner core, a fertilizer carrier layer and a controlled release coating layer. Background The current fertilizer production field, in particular to the preparation of functional fertilizers with complex structures, generally depends on the fluidized bed coating granulation technology. The technology can realize the agglomeration and the surface modification of particles by placing powder or particle materials in a fluidized state and spraying atomized adhesive or coating liquid. When the existing fluidized bed equipment is used for coping with complex processes, the existing fluidized bed equipment is mostly dependent on the combination of discrete units and manual experience intervention, and lacks of deep integration at the system level. The device has the core defects of single function, difficulty in flexibly adapting to granulation and coating process parameters with great difference in the same cavity, and cracking among the working procedures, so that the production flow is incoherent and the efficiency is low. The discrete, passive and manual-dependent empirical production mode has become a major bottleneck restricting the large-scale and stable manufacturing of high-performance multilayer composite particle products. Disclosure of Invention In order to solve the problems, the invention aims to provide an integrated fluidized bed coating system capable of meeting the requirement of precise manufacturing of complex multi-layer fertilizer particles, and has a vital meaning for pushing next-generation intelligent fertilizers to travel from a laboratory to field application. The invention focuses on the industrial production of multilayer granular fertilizers, and has the core challenge of carrying out efficient and accurate sequential construction on a chemical power unit, a nutrient carrier unit and an intelligent regulation unit through a set of integrated systems. The prior art scheme adopts the steps of sectional production by separate equipment and then assembly or rough process superposition in a single fluidized bed, so that the production process is long, the energy consumption is high, and the integrity, uniformity and functional coupling of the interface between the barrier layers cannot be ensured more importantly. For example, the brittleness of the core requires mild fluidization and spray conditions, while the construction of the fertilizer carrier layer requires strong binder penetration and particle growth kinetics, and the subsequent controlled release coating requires extremely low humidity and a specific solvent volatilization environment. Conventional single mode fluidized beds cannot dynamically adapt such a broad and contradictory process window within a single production cycle. The lack of a special production system for the multi-layer heterostructure particles leads to large dispersion of the disintegration time of the product, uneven nutrient distribution and unstable slow release performance, so that the expected 'delay-burst-slow release' effect of agronomic engineering cannot be reliably realized. The invention ensures the integrity of the self-disintegrating fertilizer granule gas-producing core, the uniformity and consistency of the thickness of each functional layer and the stability of the disintegrating property among batches through the optimization of the fluidized bed structure, the integrated design of the system and the optimization of matched technological parameters, and realizes the span from laboratory formulation to large-scale stable production. In order to achieve the above purpose, the invention adopts the following specific technical scheme: in a first aspect, the present invention provides a fluidised bed for the preparation of a multilayer structured fertiliser. Wherein: The fertilizer is a self-disintegrating type multi-layer structure fertilizer, which comprises a gas producing inner core, a fertilizer carrier layer and a controlled release coating layer from inside to outside, wherein the gas producing inner core is used for producing gas to provide disintegrating power after meeting water, the gas producing inner core can be formed by mixing and pressing citric acid and sodium bicarbonate (citric acid-sodium bicarbonate is combined with water to produce carbon dioxide), the fertilizer carrier layer is used for providing fertilizer nutrients, the fertilizer carrier layer can be formed by granulating fertilizer slurry containing organic fertilizer powder, chemical fertilizer powder (such as urea and monopotassium phosphate) and biochar powder through a binding ag