Design of compound fertilizer rolling granulator

Introduction

The equipment for producing compound fertilizers mainly includes crushers, mixers, granulators, dryers, coolers, screening machines, conditioners and packaging machines. Granulator is the main equipment in the production of compound fertilizer. It mainly includes disc granulator, twin-shaft granulator, extrusion granulator, drum granulator, fluidized bed granulator, etc.

1.Topic background and research significance

Fertilizer is the material basis of agricultural production and the food for food. Fully understanding the role and irreplaceability of fertilizers in my country’s food production and sustainable agricultural development is an important basis for thinking about sustainable agricultural development strategies and countermeasures, especially chemical fertilizers. Modern agriculture will only become an industrial system based on scientific progress. The agricultural production experience in my country and around the world has proved that among various agricultural technical measures based on scientific progress, fertilization, especially chemical fertilizers, is the fastest, most effective, and most effective. Important yield-increasing measures are the most important means to adjust the nutrient cycle and balance of farmland ecosystems. Compound fertilizer is a general term for compound fertilizer and mixed fertilizer. It refers to a commercial fertilizer that contains two or more nutrients from the three elements of nitrogen, phosphorus and potassium. The emergence and rapid development of compound fertilizers is a sign that scientific fertilization has been raised to a new level and is the basic direction of fertilizer production and use. 

2.Development history of compound fertilizer granulator

The history of pelletizing actually dates back to 1900, when cast-mode pellet machines began to be used. Over the past century, workers in pharmaceutical, feed, fertilizer and other adjacent fields have accumulated valuable experience in practice and are committed to improving the performance of granulators and improving the performance of all aspects of granulators.

3.Double shaft granulator

The double-shaft granulator is a horizontal U-shaped trough. There are two parallel rotating shafts in the trough. The shafts are equipped with paddles. The return material and slurry are added from the material port and the feed from the granulation front end respectively. Under the action of the reverse rotation of the two shafts and the blades, the materials are mixed, bonded and coated, and then agglomerated and granulated. At the same time, driven by the blades, the granulated fertilizer continuously flows to the end of the granulator, and is discharged from the Remove from the mouth.

4.Disc granulator

It is mainly composed of gearbox, belt drive, chassis, adjustment device, granulating disc and scraper mechanism. The power is transmitted to the gearbox through the belt. After the gearbox reduces the speed and increases the torque, the power is transmitted to the main shaft of the granulation plate to drive the main shaft to rotate. The mixed raw materials and return materials are added above the disc, and a liquid spray port is provided in the direction of rotation. As the material continues to tumble with the rotation of the granulating disc, the fine-grained material is bonded by the spray liquid, and the particles continue to grow; the rotation of the tilted disc causes the particles to be stratified, with large particles in the upper layer, and the particles that meet the specifications are reached. The material can be continuously discharged from the lower edge of the disc. The smaller particles in the lower layer continue to bond with the newly added materials in the disc to grow and are continuously discharged.

5.Drum granulator

It is mainly composed of feed port, slurry distributor, ammonia distributor, supporting wheel device, gear wheel, drum, gearbox, scraper mechanism and motor. The drum of the drum granulator is supported by supporting wheels and blocking wheels, and the driving device rotates the drum through gear transmission. The machine is equipped with a slurry distributor and an ammonia distributor, and the granulated product is discharged from the discharge box at the end of the drum. The drum body is equipped with a scraper mechanism to scrape off the material adhered to the drum body wall.

6.Extrusion granulator

Double roller extrusion granulator. There are two types of granulation in the roller extrusion granulator. One is that the surface of the roller is flat, and the material is extruded into flakes, and then crushed, screened and angle-grinded by the crusher to obtain particles of qualified size. product. The other is that there are spherical hollows on the surface of the rollers. After the two rollers are positioned, the material is extruded into oblate spherical granular products. The needs of the granulation process can be met by adjusting the gap between the two rollers, such as a cast-mode granulator. The rolling roller rotates on the pressing template at a linear speed of about 3/s, generating a strong accumulated force to crush the material, forcing the material to pass through the drilling holes of the template into a cylindrical strip shape, which rotates under the template The cutting knife cuts it into particles and discharges them from the discharge port. Generally, the diameter of the finished product is (φ2~φ10) mm and the length is (4~8) mm. The granulation mechanism is through mechanical pressure granulation. The raw material contains low moisture and the temperature during granulation is stable. It is especially suitable for the production of compound fertilizers using ammonia bicarbonate as raw material. Mainly include extrusion type, flat mode, ring membrane type

7.Problems

The granulators currently used in production are bulky, occupy a large area, are complex to operate and are expensive, making it difficult to meet the needs of farmers. For compound fertilizer granulation, the disadvantages of the flat die pellet machine are that the material temperature is low during operation, it is difficult to use high temperature for granulation, the granulation is loose due to low pressure, and the granulation efficiency is low. my country’s traditional compound fertilizer production process is mainly a disc granulator system. The characteristics of the process are: intermittent feeding, no random circulation of returned materials, and mainly relying on the experience of workers to control each production link. Product quality fluctuates greatly, and operability and controllability are They are all very poor and cannot achieve system mechanization and automation.