CN113087573A - Low-tower preparation method of urea-based fully water-soluble small-particle compound fertilizer - Google Patents
Low-tower preparation method of urea-based fully water-soluble small-particle compound fertilizer Download PDFInfo
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- CN113087573A CN113087573A CN202110297483.6A CN202110297483A CN113087573A CN 113087573 A CN113087573 A CN 113087573A CN 202110297483 A CN202110297483 A CN 202110297483A CN 113087573 A CN113087573 A CN 113087573A
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
- C05G3/30—Anti-agglomerating additives; Anti-solidifying additives
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05B—PHOSPHATIC FERTILISERS
- C05B7/00—Fertilisers based essentially on alkali or ammonium orthophosphates
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/10—Solid or semi-solid fertilisers, e.g. powders
- C05G5/12—Granules or flakes
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
- C05G5/00—Fertilisers characterised by their form
- C05G5/30—Layered or coated, e.g. dust-preventing coatings
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Abstract
The invention discloses a low-tower preparation method of a urea-sulfenyl fully water-soluble small-particle compound fertilizer, which uses the slurry preparation link of high-tower granulation for reference, but uses an atomizing centrifugal granulator to replace a differential granulator of a high-tower process in the granulation ring, and simultaneously reduces the height of a granulation tower from more than 100 meters to about 30 meters. By controlling the technical indexes such as different slurry temperatures, the specifications of the granulator, the discharging mode of the granulator, the rotating speed of the granulator and the like, small-particle products within the range of 0.5-2.5mm are generated after granulation. In the preparation method, the outlet size of the mixed slurry of the granulating disc is set to be 6-40mm, namely, the impurities of the slurry smaller than the outlet size can be thrown out of the granulating disc under the action of centrifugal force, and the impurities in the slurry can not exceed 5mm generally, so that the probability of material blockage can be greatly reduced, and the phenomenon of machine halt caused by material blockage is less. With the same formula and raw materials, the small-particle fertilizer has shorter dissolving time than a high-tower product, and is suitable for being used as a high-end full-water-soluble fertilizer.
Description
Technical Field
The invention belongs to the technical field of fertilizer preparation, and mainly relates to a low-tower preparation method of a urea-based fully water-soluble small-particle compound fertilizer.
Background
Fertilizers have been continuously innovated and developed as one of the essential factors for plant growth. The preparation process of the fertilizer plays an indispensable role from simple mixed fertilizer to extrusion granulation, disc granulation, drum granulation, slurry spraying granulation, high tower granulation and the like. Particularly, a high tower granulation technology represented by Shenzhen Bombay plays a very important role as a leader and a advocate in the development of the fertilizer industry in China in the last twenty years.
The high tower fertilizer has the following advantages:
1. the slurry is melted, sprayed and granulated, the moisture of the finished product is low, and the drying is not needed, so that the drying process is omitted, the floor area of a production workshop is smaller, and the production cost is low.
2. The slurry automatically condenses into spherical fertilizer particles with smooth surfaces under the action of surface tension of liquid drops in the falling process of the slurry in the tower, and the particles have high strength and are not easy to agglomerate.
3. The high tower granulation does not need to add fillers such as a binder and the like, and the fertilizer has high purity, high water solubility and stronger fertilizer efficiency.
4. Each particle has a melting hole, and the dissolution speed is high.
However, high tower granulation also has a number of problems:
1. the high tower granulation production line has high investment: the construction cost of a cement tower with the length of about 110 meters is about more than 1500 ten thousand, and the equipment investment is close to 2000 ten thousand yuan;
2. the height of the granulation tower is more than 100 meters, the air inflow is large, the dust treatment difficulty is large, and the environmental pollution diffusion radius is large;
3. the transportation of the raw materials from the ground to the tower top has high operation cost;
4. once the inner wall of the higher tower body is stuck, the tower wall is very difficult to clean, and unsafe factors are obviously increased.
A high-tower urea-based compound fertilizer is one of the main fertilizer varieties in China, and is produced by using urea as a main nitrogen source, potassium sulfate or potassium chloride as a main potassium source, monoammonium phosphate or industrial monoammonium phosphate as a main phosphorus source and other auxiliary raw materials through a high-tower granulation process. In the production process of the high-tower urea-based compound fertilizer, more than 20 percent of product particles do not meet the product standard, and the product particles need to be returned for granulation, thereby wasting energy and increasing the production cost of the fertilizer.
At present, most of compound fertilizer particles in the market are products with the particle size of 2-4.75 mm, and with the development of various fertilization technologies, formulation processes and fertilization facilities, the market demand for the compound fertilizer with the micro particles of 0.5-2.5mm is gradually increased. However, no special production process is available for producing such products, for example, the production is carried out by adopting the high tower granulation technology in the patents of 'method and system for producing compound fertilizer by high tower granulation and compound fertilizer-CN 108707000A', 'method for producing urea-based compound fertilizer by high tower granulation-CN 102584395A', 'method for producing granular compound fertilizer by high tower granulation and equipment-CN 1213001C', and small granular materials can be produced by reducing the aperture of a screen in a high tower granulator from 2-4mm to 1-2 mm, but the following problems can be caused: impurities such as infusible matters and the like exceeding the size of the sieve mesh in the raw material can block the sieve mesh or gather in the sieve mesh after the aperture of the sieve mesh is reduced, so that the cleaning is frequent, the infusible matters and the impurities comprise hard particles in the raw material, rust impurities in equipment and infusible matters generated in the pulping process, and various infusible matters can not be completely removed in the production; and secondly, the height of the tower required by the production of the compound fertilizer particles of 0.5-2.5mm is far lower than that of the tower required by the production of the compound fertilizer particles of 1-4.75 mm and is about 1/8-1/3, and the production of the product by using the original high tower system is extremely waste.
Disclosure of Invention
The invention aims to solve the defects in the high-tower granulation process technology, and provides a low-tower granulation preparation method of a urea-based fully water-soluble small-particle compound fertilizer and the urea-based fully water-soluble small-particle compound fertilizer prepared by the low-tower preparation method of the urea-based fully water-soluble small-particle compound fertilizer.
The invention uses the slurry preparation link of high tower granulation as reference for low tower granulation, but uses the atomizing granulator to replace the differential granulator of high tower technology in the granulation link, and reduces the height of the granulation tower from more than 100 meters to about 30 meters. Through controlling technical indexes such as different slurry temperatures, granulator specifications, granulator discharging modes, granulator rotating speed and the like, the slurry is granulated by an atomizing granulator to generate small-particle products within the range of 0.5-2.5 mm. And cooling, screening and grading the small particle products, coating and enveloping the small particle products, and packaging to obtain finished products.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a low-tower preparation method of a urea-based full-water-soluble small-particle compound fertilizer comprises the following steps:
s1, melting urea into slurry, and heating the slurry to 120-135 ℃; preheating a ammonium phosphate fertilizer to 120-135 ℃, uniformly mixing the ammonium phosphate fertilizer with the slurry, preheating a potassium fertilizer to 120-135 ℃, continuously adding the potassium fertilizer and uniformly mixing, and keeping the temperature of the obtained mixed slurry at 120-135 ℃ for later use; the viscosity of the mixed slurry is 1000-8000 centipoises;
s2, emulsifying the mixed slurry, and then granulating in a granulator; the granulator is a low-tower atomization centrifugal granulator, the centrifugal granulator comprises a granulating disc, and the granulating disc comprises a feed inlet, an upper granulating disc cover, a flow deflector and a lower granulating disc cover which are sequentially connected from top to bottom; the size of a slurry outlet formed by the flow deflector is between 6 and 40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the flow deflector under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the most edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc;
s3, screening the granular materials obtained after granulation: cooling the granular materials with the grain diameter of 0.5-2.5 mm; preheating the granular materials with the grain diameter of more than 2.5mm and the grain diameter of less than 0.5mm as return materials to 120-135 ℃, and then mixing and granulating again;
s4, cooling the granular material with the grain diameter of 0.5-2.5mm, and then performing anti-hardening treatment to obtain the granular material; the water content of the obtained urea-based full water-soluble small-particle compound fertilizer is 0.5-1.5%.
Preferably, the low-tower preparation method of the urea-based fully water-soluble small particle compound fertilizer is characterized in that the urea-based fully water-soluble small particle compound fertilizer is prepared from urea, a ammonium phosphate fertilizer and a potassium fertilizer, and the mass ratio of the urea to the ammonium phosphate fertilizer to the potassium fertilizer is 1-8: 1: 0.7 to 8; the urea comprises 46% nitrogen by mass; the ammonium phosphate fertilizer comprises the following components in percentage by mass: 10-15% of nitrogen and 42-62% of phosphorus pentoxide; the potash fertilizer is prepared from potassium sulfate or potassium chloride: when potassium sulfate is selected, the obtained product is a urine sulfur-based series small-particle compound fertilizer; when potassium chloride is selected, the obtained product is a urea-chlorine-based series small-particle compound fertilizer;
preferably, the low-tower preparation method of the urea-based full water-soluble small-particle compound fertilizer comprises the following steps:
s1, adding urea into a first reaction kettle to be melted into slurry, and heating the slurry to 120-135 ℃ for later use;
s2, preheating a ammonium phosphate fertilizer to 120-135 ℃, adding the ammonium phosphate fertilizer into the first reaction kettle, and uniformly mixing the ammonium phosphate fertilizer with slurry to obtain mixed slurry, wherein the temperature of the obtained mixed slurry is kept at 120-135 ℃ for later use;
s3, preheating potassium sulfate or potassium chloride to 120-135 ℃, adding the potassium sulfate or potassium chloride into the first reaction kettle, and uniformly mixing the potassium sulfate or potassium chloride with the mixed slurry, wherein the temperature of the slurry in the first reaction kettle is kept at 120-135 ℃ for later use;
s4, opening a discharge valve of the first reaction kettle to enable all internal slurry to enter a second reaction kettle, and keeping the temperature of the slurry in the second reaction kettle at 120-135 ℃ for later use;
s5, discharging the material from the second reaction kettle, emulsifying the prepared slurry by an emulsifying machine, and then granulating in a granulator; the granulator is a low-tower atomization centrifugal granulator, the centrifugal granulator comprises a granulating disc, and the granulating disc comprises a feed inlet, an upper granulating disc cover, a flow deflector and a lower granulating disc cover which are sequentially connected from top to bottom; the size of a slurry outlet formed by the flow deflector is between 6 and 40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the flow deflector under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the most edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc;
s6, screening the granulated materials obtained after granulation: cooling the granular materials with the grain diameter of 0.5-2.5 mm; after being crushed, the granular materials with the grain size of more than 2.5mm and the granular materials with the grain size of less than 0.5mm are preheated to 120-135 ℃ as return materials and then enter a second reaction kettle for re-mixing and granulation;
s7, cooling the granular materials with the grain diameter of 0.5-2.5mm, then performing anti-hardening treatment, then continuously screening, screening out three granular materials with different grain diameter ranges of 0.5-1.0 mm, more than 1.0mm and less than 2.0mm and 2.0-2.5 mm, and then respectively packaging and warehousing.
The invention optimizes the formula of the urea-based compound fertilizer, innovatively develops a low-tower granulation method, and greatly reduces the construction cost and the production cost. In the preparation method, the outlet size of the mixed slurry of the granulating disc is set to be 6-40mm, namely, the slurry impurities smaller than the outlet size can be thrown out from the granulating disc under the action of centrifugal force, and the impurities in the slurry can not exceed 5mm generally, so that compared with high tower granulation, the method can greatly reduce the probability of material blockage and reduce the phenomenon of machine halt caused by material blockage.
The particle size of the granulated fertilizer is 0.5-2.5mm, and the compound fertilizer particles with the particle size of 0.5-2.5mm are smaller, so that the specific surface area is larger under the same weight compared with the compound fertilizer particles with the particle size of 2-4mm, namely, the contact area with air is larger under the condition of the same weight in the falling process of the particles, so that the falling height required by the particles with the particle size of 0.5-2.5mm is smaller and is about 1/5-1/3 of the falling height of the particles with the particle size of 2-4mm, namely, the required height of a granulation tower is 1/5-1/3 of the granulation of an original high tower, and the low tower granulation can be.
The production process of the low-tower small-particle fertilizer researched by the invention has the following advantages:
1. inherits all the advantages of high tower granulation series products.
2. The height of the granulation tower is reduced to be within 30 meters, and the construction cost of each production line can be reduced by about one million yuan.
3. Because the tower height is effectively reduced, the raw material is easier to convey, and the production cost is effectively reduced.
4. The reduction of the tower height makes the internal cleaning easier and the production control safer.
5. The small-particle fertilizer has the same formula and raw materials, has shorter dissolving time than a high-tower product, and is suitable for being used as a high-end full-water-soluble fertilizer.
6. The low tower process has small air input, easy dust treatment, easy control of air pollution and low environmental protection treatment cost.
7. The special structure of the low-tower granulation process atomization granulator can not cause the blockage phenomenon of the granulator, so that the production operation is easier to control than a high-tower granulator, and the production continuity is stronger.
8. The low tower granulation process has stronger formula applicability and rich product specifications.
In the present invention, preferably, the ammonium phosphate fertilizer is agricultural grade monoammonium phosphate or industrial grade monoammonium phosphate, including but not limited to one or more of monoammonium phosphate 11-44-0, monoammonium phosphate 10-50-0, monoammonium phosphate 12-61-0, and monoammonium phosphate 14.5-57.5-0.
In the invention, preferably, the potassium sulfate is powdery potassium sulfate and comprises 45-52% of potassium oxide in percentage by mass; the potassium chloride is powdery potassium chloride and comprises 55-62% of potassium oxide in percentage by mass.
In the invention, preferably, in the granulation process, the rotation speed of the granulator is set to be 300-1000 rpm, and the granulator heat tracing system and the slurry pipeline steam heat tracing system are started at the same time, so that the granulator and the slurry pipeline are at the appropriate temperature (120-.
In the invention, liquid drops thrown out of the granulating disc fall under the action of gravity, and are cooled by air in the falling process to become small-particle solids; the bottom of the granulator is provided with a receiving hopper and a fan, and air cooling can be carried out by forced ventilation through the fan or natural ventilation without installing the fan.
The temperature of the liquid drops is high, the air temperature is low, the liquid drops exchange heat with the air in the falling process, the air can be considered as air with the normal temperature of 25 ℃ because the air circulates, so the liquid drops can exchange heat with the air all the time as long as the temperature of the liquid drops is higher than 25 ℃, and when the temperature of the liquid drops is gradually cooled to be lower than the melting point, the liquid drops are changed into solid particles; as the solid particles fall gradually, the solid particles continue to exchange heat with the air and the temperature is gradually reduced, and as the temperature of the solid particles is reduced, the strength of the solid particles is gradually increased; when the temperature of the solid particles is reduced to 50-70 ℃, the strength of the solid particles meets the conveying requirement of a subsequent working section, at the moment, the solid particles fall onto a material collector at the bottom of the tower, are collected by the material collector and then are conveyed to the subsequent working section, and a finished product is obtained after cooling, film coating and packaging.
In the invention, preferably, the preheating adopts a preheating device, and the preheating device is provided with a discharge valve; the slurry is evenly mixed by mechanical stirring in the mixing process. The preheating device is necessary, so that the slurry preparation time can be effectively shortened, and the yield is improved.
In the invention, preferably, the first reaction kettle and the second reaction kettle are both provided with a steam heating system, and the steam heating system is provided with a temperature sensor and a steam inlet regulating valve for controlling the heating steam amount; when the temperature sensor detects that the temperature of the slurry is higher than the set temperature, the steam inlet regulating valve reduces the opening degree and reduces the amount of steam for heating, so that the temperature is reduced; when the temperature sensor detects that the temperature of the slurry is lower than the set temperature, the steam inlet regulating valve increases the opening degree, the amount of steam for heating is increased, and the temperature is increased. The first reaction kettle and the second reaction kettle are arranged, so that the height of the granulation tower is effectively reduced on the basis of not influencing process control and product quality, the production configuration is simpler, the device is more compact, and the control is easier.
In the invention, preferably, the method further comprises a tail gas treatment process, wherein the tail gas treatment process adopts a tail gas treatment device; the tail gas treatment device comprises a dynamic wave washing tower, a dynamic wave washing tower circulating water pump, a draught fan, a washing tower circulating water pump and a chimney. The washing tower takes water as washing liquid, solid particles in the tail gas are adsorbed into the water through gas-liquid two-phase contact, the tail gas is discharged completely, the dynamic wave washing tower is characterized in that a downstream mixing element is additionally arranged in a common washing tower, so that the gas-liquid two phases are subjected to turbulent mixing again, the downstream washing effect is achieved, and the two-stage series washing effect can be realized.
Compared with the prior art, the invention has the beneficial effects that:
1. inherits all the advantages of high tower granulation series products.
2. The height of the granulation tower is reduced to be within 30 meters, and the construction cost of each production line can be reduced by about one million yuan.
3. Because the tower height is effectively reduced, the raw material is easier to convey, and the production cost is effectively reduced.
4. The reduction of the tower height makes the internal cleaning easier and the production control safer.
5. The small-particle fertilizer has the same formula and raw materials, has shorter dissolving time than a high-tower product, and is suitable for being used as a high-end full-water-soluble fertilizer.
6. The low tower process has small air input, easy dust treatment, easy control of air pollution and low environmental protection treatment cost.
7. The special structure of the low-tower granulation process atomization granulator can not cause the blockage phenomenon of the granulator, so that the production operation is easier to control than a high-tower granulator, and the production continuity is stronger.
8. The low tower granulation process has stronger formula applicability and rich product specifications.
Drawings
FIG. 1 is a process flow chart of a low-tower preparation method of a urea-based full water-soluble small-particle compound fertilizer.
Fig. 2 is a schematic view of the structure of a pelletizing disk according to the invention.
FIG. 3 is a schematic view of centrifugal granulation by a granulation disk according to the present invention.
FIG. 4 is a schematic view of the structure of the tail gas treatment device of the present invention.
Wherein, the technical characteristics corresponding to the marks in the drawings are as follows: 1-an upper cover of a granulating disc, 2-a lower cover of the granulating disc, 3-a flow deflector, 4-a feed inlet, 5-a dynamic wave washing tower, 6-a circulating water pump of the dynamic wave washing tower, 7-an induced draft fan, 8-the washing tower, 9-a circulating water pump of the washing tower and 10-a chimney.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of the present invention is not limited to the embodiments.
The starting materials used in the following examples are all commercially available unless otherwise specified.
Example 1:
preparing a urea-based full water-soluble small-particle compound fertilizer in a low tower:
1. the steam heating system of the first reaction kettle is started, and 5700kg of urea (nitrogen 46%) is slowly added into the first reaction kettle. When the materials are completely melted, the slurry is continuously heated to about 125 ℃ for standby.
2. Starting a ammonium phosphate preheating device, and slowly adding 1300kg of industrial grade monoammonium phosphate (12% of nitrogen and 60% of phosphorus pentoxide) into the preheating device. When the temperature of the ammonium phosphate reaches about 125 ℃, a discharge valve of the preheating device is opened, the ammonium phosphate is slowly added into the first reaction kettle, and the powdery material is fully and uniformly mixed with the urea slurry under the action of the stirrer. And controlling the steam heating system of the first reaction kettle to keep the temperature of the slurry at about 125 ℃ for later use.
3. And closing a discharge valve of the ammonium phosphate preheating device, adding monoammonium phosphate according to the formula proportion again, and preheating to about 125 ℃ for later use.
4. In step 2, a potassium fertilizer preheating device is started, 3000kg of powdery potassium sulfate (52 percent of potassium oxide) is slowly added into the preheating device, and the temperature of the powdery potassium sulfate is raised to about 125 ℃ for later use. And when the temperature of the slurry in the first reaction kettle reaches about 125 ℃, and monoammonium phosphate is uniformly stirred and reaches a set temperature, starting a discharge valve of the potassium sulfate preheating device, and slowly adding potassium sulfate into the first reaction kettle. The powdery material is fully and uniformly mixed with the mixed slurry of urea and monoammonium phosphate under the action of the stirrer. And controlling the steam heating system of the first reaction kettle to keep the temperature of the internal slurry within the range of 125-130 ℃ for later use.
5. Closing a discharge valve of the potassium fertilizer preheating device, adding potassium sulfate according to the formula proportion again, and preheating to about 125 ℃ for later use.
6. And opening a discharge valve of the first reaction kettle to enable all the slurry to enter the second reaction kettle, and simultaneously starting a steam heating system of the second reaction kettle to enable the temperature of the slurry in the second reaction kettle to be kept at 125-130 ℃ for later use.
7. And closing a discharge valve of the first reaction kettle, and repeating the melt process of 1-5.
8. The pelletizer was turned on and brought to the appropriate speed (700 rpm). And simultaneously starting a granulator heat tracing system and a slurry pipeline steam heat tracing system to keep the granulator and the slurry pipeline at proper temperature (about 125 ℃).
9. The emulsifying machine is started.
10. And opening a discharge valve of the second reaction kettle, and emulsifying the prepared slurry by an emulsifying machine and then feeding the emulsified slurry into a granulator for granulation.
11. And (4) starting a material receiving belt conveyor and a screening machine at the bottom of the granulating tower, and enabling the granular materials from the granulating machine to enter the No. 1 screening machine for screening. Qualified particles within the range of 0.5-2.5mm enter a cooling system for cooling; and (3) crushing the particles larger than 2.5mm by using a crusher, returning the crushed particles and small particle materials smaller than 0.5mm to a material returning and preheating system, heating the crushed particles to 125 ℃ by using the preheating system, and slowly feeding the heated particles into a second reaction kettle for re-mixing and granulation.
12. And (4) feeding the granular materials from the cooling system into a coating system for anti-hardening treatment.
13. The anti-hardening processed granular materials enter a No. 2 sieving machine, are classified into materials with different particle ranges of 0.5-1.0 mm/larger than 1.0 mm/smaller than 2.0 mm/2.0-2.5 mm and the like, and enter finished product bins with different specifications through a conveyer.
14. And packaging the materials in the finished product bins of various specifications by a finished product packaging system and warehousing.
15. The operations 1-14 are repeated to continuously produce 28-8-15 urine sulfur-based full water-soluble small particle compound fertilizer.
The granulator that the embodiment adopted is low tower atomizing centrifugal granulator, and centrifugal granulator includes the granulation dish, the granulation dish includes feed inlet 4, granulation dish upper cover 1, water conservancy diversion piece 3 and granulation dish lower cover 2 (as shown in fig. 2) that connect gradually from last to down. The size of a slurry outlet formed by the flow deflector is between 6 and 40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the guide vane under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc (as shown in figure 3).
The preparation process of the compound fertilizer also comprises a tail gas treatment process, and the tail gas treatment process adopts a tail gas treatment device. As shown in fig. 4, the tail gas treatment device includes a dynamic wave washing tower 5, a dynamic wave washing tower circulating water pump 6, an induced draft fan 7, a washing tower 8, a washing tower circulating water pump 9 and a chimney 10.
Example 2:
preparing a urea-based full water-soluble small-particle compound fertilizer in a low tower:
1. the first autoclave steam heating system was turned on and 4100kg of urea (nitrogen 46%) was slowly added to the first autoclave. When the materials are completely melted, the slurry is continuously heated to about 135 ℃ for standby.
2. The ammonium phosphate preheating device is started, and 1600kg of industrial grade monoammonium phosphate (12% nitrogen and 60% phosphorus pentoxide) is slowly added into the preheating device. When the temperature of the ammonium phosphate reaches about 135 ℃, a discharge valve of the preheating device is opened, the ammonium phosphate is slowly added into the first reaction kettle, and the powdery material is fully and uniformly mixed with the compound fertilizer slurry of the phosphorus nitrate under the action of the stirrer. And controlling the steam heating system of the first reaction kettle to keep the temperature of the slurry at about 135 ℃ for later use.
3. And closing a discharge valve of the ammonium phosphate preheating device, adding monoammonium phosphate according to the formula proportion again, and preheating to about 135 ℃ for later use.
4. In step 2, the potassium fertilizer preheating device is started, 4300kg of powdery potassium chloride (62 percent of potassium oxide) is slowly added into the preheating device, and the temperature of the powdery potassium chloride is raised to about 135 ℃ for later use. And when the temperature of the slurry in the first reaction kettle reaches about 135 ℃, and monoammonium phosphate is uniformly stirred and reaches a set temperature, opening a discharge valve of the potash fertilizer preheating device, and slowly adding potassium chloride into the first reaction kettle. The powdery material is fully and uniformly mixed with the mixed slurry of urea and monoammonium phosphate under the action of the stirrer. And controlling the steam heating system of the first reaction kettle to keep the temperature of the internal slurry within the range of 130-135 ℃ for later use.
5. Closing a discharge valve of the potassium fertilizer preheating device, adding potassium chloride again according to the formula proportion, and preheating to about 135 ℃ for later use.
6. And opening a discharge valve of the first reaction kettle to enable all the slurry to enter a second reaction kettle, and simultaneously starting a steam heating system of the second reaction kettle to enable the temperature of the slurry in the second reaction kettle to be kept at 130-135 ℃ for later use.
7. And closing a discharge valve of the first reaction kettle, and repeating the melt process of 1-5.
8. The pelletizer is turned on and brought to the appropriate speed (900 rpm). And simultaneously starting a granulator heat tracing system and a slurry pipeline steam heat tracing system to keep the granulator and the slurry pipeline at proper temperature (about 135 ℃).
9. The emulsifying machine is started.
10. And opening a discharge valve of the second reaction kettle, and emulsifying the prepared slurry by an emulsifying machine and then feeding the emulsified slurry into a granulator for granulation.
11. And (4) starting a material receiving belt conveyor and a screening machine at the bottom of the granulating tower, and enabling the granular materials from the granulating machine to enter the No. 1 screening machine for screening. Qualified particles within the range of 0.5-2.5mm enter a cooling system for cooling; and (3) crushing the particles larger than 2.5mm by using a crusher, returning the crushed particles and small particle materials smaller than 0.5mm to a material returning preheating system, heating the crushed particles to 135 ℃ by using the preheating system, slowly feeding the heated particles into a second reaction kettle, and mixing and granulating the particles again.
12. And (4) feeding the granular materials from the cooling system into a coating system for anti-hardening treatment.
13. The anti-hardening processed granular materials enter a No. 2 sieving machine, are classified into materials with different particle ranges of 0.5-1.0 mm/larger than 1.0 mm/smaller than 2.0 mm/2.0-2.5 mm and the like, and enter finished product bins with different specifications through a conveyer.
14. And packaging the materials in the finished product bins of various specifications by a finished product packaging system and warehousing.
15. The operation of 1 to 14 is repeated, and the urea-chlorine-based full water-soluble small particle compound fertilizer with the nutrient specification of 20 to 10 to 27 can be continuously produced.
Example 3:
preparing a urea-based full water-soluble small-particle compound fertilizer in a low tower:
1. the first autoclave steam heating system was turned on and 4500kg of urea (nitrogen 46%) was added slowly to the first autoclave. When the materials are completely melted, the slurry is continuously heated to about 130 ℃ for standby.
2. The ammonium phosphate preheater was started and 4500kg of monoammonium phosphate (10% nitrogen, 50% phosphorus pentoxide) was slowly added to the preheater. When the temperature of the ammonium phosphate reaches about 130 ℃, a discharge valve of the preheating device is opened, the ammonium phosphate is slowly added into the first reaction kettle, and the powdery material is fully and uniformly mixed with the compound fertilizer slurry of the phosphorus nitrate under the action of the stirrer. And controlling the steam heating system of the first reaction kettle to keep the temperature of the slurry at about 130 ℃ for later use.
3. And closing a discharge valve of the ammonium phosphate preheating device, adding monoammonium phosphate according to the formula proportion again, and preheating to about 130 ℃ for later use.
4. In step 2, a potassium fertilizer preheating device is started, 1000kg of powdery potassium chloride (60 percent of potassium oxide) is slowly added into the preheating device, and the temperature of the powdery potassium chloride is raised to about 130 ℃ for later use. And when the temperature of the slurry in the first reaction kettle reaches about 130 ℃, and monoammonium phosphate is uniformly stirred and reaches a set temperature, opening a discharge valve of the potash fertilizer preheating device, and slowly adding potassium chloride into the first reaction kettle. The powdery material is fully and uniformly mixed with the mixed slurry of urea and monoammonium phosphate under the action of the stirrer. And controlling the steam heating system of the first reaction kettle to keep the temperature of the internal slurry within the range of 125-130 ℃ for later use.
5. Closing a discharge valve of the potassium fertilizer preheating device, adding potassium chloride again according to the formula proportion, and preheating to about 130 ℃ for later use.
6. And opening a discharge valve of the first reaction kettle to enable all the slurry to enter the second reaction kettle, and simultaneously starting a steam heating system of the second reaction kettle to enable the temperature of the slurry in the second reaction kettle to be kept at 125-130 ℃ for later use.
7. And closing a discharge valve of the first reaction kettle, and repeating the melt process of 1-5.
8. The pelletizer was turned on and was set at the appropriate speed (800 rpm). And simultaneously starting a granulator heat tracing system and a slurry pipeline steam heat tracing system to keep the granulator and the slurry pipeline at proper temperature (about 130 ℃).
9. The emulsifying machine is started.
10. And opening a discharge valve of the second reaction kettle, and emulsifying the prepared slurry by an emulsifying machine and then feeding the emulsified slurry into a granulator for granulation.
11. And (4) starting a material receiving belt conveyor and a screening machine at the bottom of the granulating tower, and enabling the granular materials from the granulating machine to enter the No. 1 screening machine for screening. Qualified particles within the range of 0.5-2.5mm enter a cooling system for cooling; and (3) crushing the particles larger than 2.5mm by using a crusher, returning the crushed particles and small particle materials smaller than 0.5mm to a material returning preheating system, heating the crushed particles to 130 ℃ by using the preheating system, and slowly feeding the heated particles into a second reaction kettle for re-mixing and granulation.
12. And (4) feeding the granular materials from the cooling system into a coating system for anti-hardening treatment.
13. The anti-hardening processed granular materials enter a No. 2 sieving machine, are classified into materials with different particle ranges of 0.5-1.0 mm/larger than 1.0 mm/smaller than 2.0 mm/2.0-2.5 mm and the like, and enter finished product bins with different specifications through a conveyer.
14. And packaging the materials in the finished product bins of various specifications by a finished product packaging system and warehousing.
15. The operation of 1 to 14 is repeated, and the urea-chlorine-based full water-soluble small particle compound fertilizer with the nutrient specification of 25 to 22 to 6 can be continuously produced.
Performance testing
Comparing the urine sulfur-based full water-soluble small particle compound fertilizer prepared in the embodiment 1 of the invention with the conventional water-soluble fertilizer sold in the market, the water solubility, the water insoluble substance and the fertilizer efficiency are tested, and the results are as follows:
TABLE 1
Test results show that the urine sulfur-based fully water-soluble small particle compound fertilizer prepared in the embodiment 1 of the invention is fast in dispersion and dissolution in water, compared with the conventional water-soluble fertilizer, the dissolution time is shortened by more than 30%, and under the condition of the same fertilizing amount of the same fertilizing facility, the fertilizer is fast in dissolution, the fertilizing time is shortened, the fertilizing efficiency is improved, and the yield is improved by more than 10% compared with the conventional water-soluble fertilizer.
The urine sulfur-based full water-soluble small particle compound fertilizer prepared in the embodiment 1-3 is applied to field crops such as wheat and corn which are fertilized at one time, and the yield of the field crops is averagely increased by 6.5% -12.6%. The fertilizer is applied to crops with longer fertilizer application times in the growth period, such as fruit trees, melons and beans, the fertilizer application times are averagely reduced by 1 to 3 times, the yield is averagely improved by 10.3 to 23.3 percent, the content of soluble sugar is averagely improved by 8.6 to 14.1 percent, and the content of vitamin C is averagely improved by 5.1 to 11.8 percent.
Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (10)
1. A low-tower preparation method of a urea-based full-water-soluble small-particle compound fertilizer is characterized by comprising the following steps:
s1, melting urea into slurry, and heating the slurry to 120-135 ℃; preheating a ammonium phosphate fertilizer to 120-135 ℃, uniformly mixing the ammonium phosphate fertilizer with the slurry, preheating a potassium fertilizer to 120-135 ℃, continuously adding the potassium fertilizer and uniformly mixing, and keeping the temperature of the obtained mixed slurry at 120-135 ℃ for later use; the viscosity of the mixed slurry is 1000-8000 centipoises;
s2, emulsifying the mixed slurry, and then granulating in a granulator; the granulator is a low-tower atomization centrifugal granulator, the centrifugal granulator comprises a granulating disc, and the granulating disc comprises a feed inlet, an upper granulating disc cover, a flow deflector and a lower granulating disc cover which are sequentially connected from top to bottom; the size of a slurry outlet formed by the flow deflector is between 6 and 40 mm; after the slurry flows into the granulating disc through the feed inlet, the granulating disc rotates at a high speed, so that the slurry moves towards the edge of the granulating disc along the flow deflector under the action of centrifugal force, the slurry gradually extends into a film in the moving process, and when the slurry moves to the most edge of the granulating disc, the slurry is changed into fine liquid drops from the film under the action of centrifugal force and is thrown out of the granulating disc;
s3, screening the granular materials obtained after granulation: cooling the granular materials with the grain diameter of 0.5-2.5 mm; preheating the granular materials with the grain diameter of more than 2.5mm and the grain diameter of less than 0.5mm as return materials to 120-135 ℃, and then mixing and granulating again;
s4, cooling the granular material with the grain diameter of 0.5-2.5mm, and then performing anti-hardening treatment to obtain the granular material; the water content of the obtained urea-based full water-soluble small-particle compound fertilizer is 0.5-1.5%.
2. The low-tower preparation method of the urea-based fully water-soluble small particle compound fertilizer as claimed in claim 1, wherein the urea-based fully water-soluble small particle compound fertilizer is prepared from urea, ammonium phosphate fertilizer and potash fertilizer, and the mass ratio of the urea to the ammonium phosphate fertilizer to the potash fertilizer is 1-8: 1: 0.7 to 8; the urea comprises 46% nitrogen by mass; the ammonium phosphate fertilizer comprises the following components in percentage by mass: 10-15% of nitrogen and 42-62% of phosphorus pentoxide; the potash fertilizer is prepared from potassium sulfate or potassium chloride: when potassium sulfate is selected, the obtained product is a urine sulfur-based series small-particle compound fertilizer; when potassium chloride is selected, the obtained product is urea-chlorine-based series small-particle compound fertilizer.
3. The low tower production method of a urea-based fully water-soluble small particle compound fertilizer as claimed in claim 2, wherein the ammonium phosphate fertilizer is agricultural grade monoammonium phosphate or industrial grade monoammonium phosphate, including but not limited to: 11-44-0 monoammonium phosphate, 10-50-0 monoammonium phosphate, 12-61-0 industrial monoammonium phosphate, and 14.5-57.5-0 industrial monoammonium phosphate.
4. The low-tower preparation method of the urea-based full-water-soluble small-particle compound fertilizer as claimed in claim 2, wherein the potassium sulfate is powdery potassium sulfate and comprises 45-52% by mass of potassium oxide; the potassium chloride is powdery potassium chloride and comprises 55-62% of potassium oxide in percentage by mass.
5. The low-tower preparation method of the urea-based fully water-soluble small-particle compound fertilizer as claimed in claim 1, wherein in the granulation process, the rotation speed of the granulator is set to 300-1000 rpm, and the granulator heat tracing system and the slurry pipeline steam heat tracing system are started simultaneously to enable the granulator and the slurry pipeline to be at 120-135 ℃.
6. The low-tower preparation method of the urine-based all-water soluble small particle compound fertilizer as claimed in claim 1, wherein the preheating adopts a preheating device, and the preheating device is provided with a discharge valve; the slurry is evenly mixed by mechanical stirring in the mixing process.
7. The low-tower preparation method of a urea-based all-water soluble small-particle compound fertilizer as claimed in claim 1, wherein the liquid drops thrown from the inside of the granulation disc fall under the action of gravity, and are cooled by air to become small-particle solids in the falling process; the bottom of the granulator is provided with a receiving hopper and a fan, and air cooling can be carried out by forced ventilation through the fan or natural ventilation without installing the fan.
8. The low-tower preparation method of the urea-based all-water soluble small particle compound fertilizer as claimed in claim 1, wherein a first reaction kettle and a second reaction kettle are adopted in the preparation process; the first reaction kettle and the second reaction kettle are both provided with steam heating systems, and the steam heating systems are provided with temperature sensors and steam inlet regulating valves for controlling heating steam quantity; when the temperature sensor detects that the temperature of the slurry is higher than the set temperature, the steam inlet regulating valve reduces the opening degree and reduces the amount of steam for heating, so that the temperature is reduced; when the temperature sensor detects that the temperature of the slurry is lower than the set temperature, the steam inlet regulating valve increases the opening degree, the amount of steam for heating is increased, and the temperature is increased.
9. The low-tower preparation method of the urea-based full water-soluble small particle compound fertilizer as claimed in claim 1, further comprising a tail gas treatment process, wherein a tail gas treatment device is adopted in the tail gas treatment process; the tail gas treatment device comprises a dynamic wave washing tower, a dynamic wave washing tower circulating water pump, a draught fan, a washing tower circulating water pump and a chimney.
10. The urea-based water-soluble small particle compound fertilizer prepared by the low-tower preparation method of the urea-based water-soluble small particle compound fertilizer as claimed in any one of claims 1 to 9.
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Application publication date: 20210709 |