NPK Compound fertilizer dryer Introduction

Compound fertilizer rotary dryer is a type of industrial equipment used to efficiently dry granular or powdered materials that are composed of multiple nutrients, typically used as fertilizers. The rotary dryer is a device that uses rotating drums or cylinders to facilitate the drying process, the rotary dryer is employed to reduce the moisture content of the fertilizer materials. This is important because excess moisture can lead to issues such as caking, clumping, and reduced shelf life of the fertilizer. Compound fertilizers are blends of different essential nutrients, such as nitrogen, phosphorus, and potassium, along with other trace minerals, that are combined to create a balanced formula that promotes plant growth and development.

Compound fertilizer dryer structure

The structure of a compound fertilizer dryer can vary based on the specific design, generally it is composed of the following parts: riding rings, girth gear, supporting device, pinion, hood cover, gear cover, shell, transmission and so on.

Dryer Shell: The npk compound fertilizer dryer shell is a thick, steel cylindrical structure that provides the necessary strength and rigidity to withstand the high-temperature environment inside the dryer. It also serves as a containment vessel for the materials and gases during the cement manufacturing process. Inside the dryer shell is the refractory lining usually refractory bricks or sometimes refractory castable. Tongli dryer shell has good sealing performance, the edge of each shell is machined smoothly, enhance the sealing and service life of the rotary drum.

Dryer Flights: Compound fertilizer dryer flights, also known as "flights" or "lifters," are the inclined, curved structures that are attached to the internal shell of a rotary dryer. A rotary dryer is a device used to remove moisture from materials like powders, granules, and bulk solids through the process of drying. It consists of a large cylindrical drum that rotates while the material is fed into one end and is discharged from the other end after being dried.

Riding Rings(Tyre): The Compound fertilizer dryer shell is supported on multiple riding rings usually 2~3, which are attached to the shell with point-welded padding on the inside. The Compound fertilizer dryer riding rings allow the dryer to rotate smoothly on its axis and help distribute the dryer's weight. The thickness of the plate under the riding ring is increased to facilitate strength of the shell.

Girth Gear: The Compound fertilizer dryer girth gear is a large gear ring encircling the dryer, usually mounted on the dryer shell. It is driven by a pinion gear, and together they form the primary drive unit to rotate the dryer.

Supporting Device: Compound fertilizer dryer supporting device is composed of the supporting roller and thrust roller, the shaft is a forged object to prolong the service life time of the Compound fertilizer dryer. One thing features about Tongli Supporting device is all the metal casting are produced by our own, the quality is guaranteed. All the metal casting supporting roller, metal casting thrust roller are machined and heat treated, the performance measure is reliable.

Compound fertilizer dryer thrust roller：The thrust roller is a critical part of the Compound fertilizer dryer system. It serves the purpose of supporting the dryer's weight and maintaining its axial position, ensuring that the dryer remains properly aligned along its axis. The thrust roller is typically positioned on the downhill side of the dryer and is attached to the dryer shell. It consists of a central shaft or journal and a roller assembly.

Rotary dryer pinion: The pinion is an essential part of the Compound fertilizer dryer drive system, responsible for transmitting rotational motion and torque from the driving mechanism to the Compound fertilizer dryer itself. It consists of a gear wheel with teeth that mesh with the teeth of a larger gear, often referred to as the "girth gear" or "ring gear." The girth gear is attached to the outer shell of the Compound fertilizer dryer. When the pinion is rotated by the drive system, it drives the girth gear, causing the Compound fertilizer dryer to rotate.

Compound fertilizer dryer bearing housing: The bearing housing serves as the support structure for the dryer's rotating motion and is responsible for holding and guiding the dryer's trunnion bearings. Trunnion bearings are large, heavy-duty bearings that support the weight of the dryer and allow it to rotate smoothly. These bearings are subject to high loads, extreme temperatures, and potentially harsh environments due to the nature of the processes occurring inside the Compound fertilizer dryer. The bearing housing provides a stable mounting point for the trunnion bearings and ensures proper alignment of the dryer's rotation. It is typically designed to accommodate the axial and radial forces generated during the rotation of the dryer.

Dryer Hood Cover: The Compound fertilizer dryer hood is located at the discharge end of the dryer and provides sealing to retain heat and gases. The Compound fertilizer dryer operates under the negative pressure, therefore Tongli implied SS304 lining plate and ceramic felt both in the front and back end to prevent heat leakage.

Compound fertilizer dryer Transmission device: The transmission device of the Compound fertilizer dryer is mainly composed of main transmission, auxiliary transmission, mechanical thrust roller/hydraulic thrust roller, motor, gearbox and other components. The unique design of tongli transmission can greatly improve the service life and safety performance of the equipment.

PLC control system: A PLC is a digital computer-based system that is designed to control various industrial processes automatically. In the context of a Compound fertilizer dryer, a PLC is used to monitor and control parameters such as temperature, rotation speed, air flow, fuel flow, and other critical variables that affect the performance of the dryer and the quality of the products being processed. Usually, the Compound fertilizer dryer control system is integrated in the whole factory’s plc system, therefore we will provide the on-site cabin and a signal cable to the central plc.

Design principles of compound fertilizer rotary dryer

Counter-Current Flow: Tongli Compound fertilizer dryers are designed with a counter-current flow arrangement. In this design, the raw materials and air move in opposite directions. The raw material enters from the upper end, while the air exit from the lower end. This counter-current flow enhances heat transfer efficiency and reduces energy consumption.

Gradual Heating: The raw materials are gradually heated as they move through the Compound fertilizer dryer. This gradual heating is crucial to avoid thermal shocks and to facilitate the complex chemical reactions that convert raw materials into cement clinker.

Drum Design: The central component of a rotary dryer is the rotating drum. The drum's design should optimize material agitation, mixing, and tumbling to ensure uniform distribution of the granulating liquid and consistent granule formation. The drum's angle, speed, and internal baffles can all influence these factors.

Material Flow and Residence Time: The residence time of material within the drum affects granule size and quality. The design should promote controlled and consistent material flow through the drum, allowing sufficient time for the granulation process to occur without excessive agglomeration or over-granulation.

Large processing capacity: Tongli Pellet rotary dryer has a strong overload resistance, high thermal efficiency and low coal consumption, which reduces the drying cost by about 20%.

Scalability: Tongli Pellet rotary dryer has strong scalability, and the design considers the production margin. Even if the output increases slightly, there is no need to replace the equipment.

Structural innovation: Tongli fertilizer rotary dryer has achieved innovation in the internal structure, strengthened the cleaning and heat transfer effect on the dispersed materials, and eliminated the sticking phenomenon on the inner wall of the drum.

Advanced design: Tongli Pellet rotary dryer uses a new type of feeding and discharging device, which prevents the Pellet rotary dryer from feeding blockage, discontinuity, unevenness and return phenomena, and reduces the load of your dust removal system. The equipment has made many technical innovations in the lifting device system, especially adopting a new type of multi-combination lifting device, which overcomes the “wind tunnel” phenomenon of traditional dryers.

Specifications of compound fertilizer dryer

How is npk fertilizer manufactured?

NPK fertilizer is produced through fertilizer manufacturing equipment, which requires the use of equipment such as granulators. It involves several steps, including raw material preparation, ingredient mixing, crushing and screening, wet granulation, drying, screening, and packaging. These steps are necessary to produce high-quality products.

Raw material preparation: The manufacturing of NPK fertilizer requires selecting appropriate proportions of nitrogen, phosphorus, and potassium sources. Common nitrogen sources include urea, ammonium salts, and ammonium nitrate; phosphorus sources can be diammonium phosphate, monoammonium phosphate, or ammonium phosphate; potassium sources typically come from potassium chloride, potassium sulfate, or potassium nitrate. The proportions of raw materials can be adjusted based on the requirements of different crops and soils.

Ingredient mixing: Pre-weighed nitrogen, phosphorus, and potassium raw materials are mixed according to specific formulas. Precise control of the proportions of each component is necessary during the mixing process to ensure the final product meets the required standards. Additionally, trace elements and other nutrients may be added to enhance the overall effectiveness of the fertilizer.

Crushing and screening: The mixed raw materials need to undergo crushing and screening to achieve the desired particle size and uniformity. This can be achieved using crushers and screening equipment. The process of crushing and screening helps improve the solubility and absorption rate of the fertilizer.

Wet granulation: After crushing and screening, the raw materials enter the wet granulation process. During this process, the raw materials are mixed and moistened with additives such as binders or coagulants. The moistened materials are then fed into a rotary granulator or extrusion granulator, forming granular materials inside the machine. The added binders or coagulants enhance the stability and crush resistance of the granules.

Drying: The granules produced through wet granulation need to be dried to remove excess moisture. Drying methods such as air drying, airflow drying, or rotary drying are typically employed. The dried granules become hard and resistant to breakage.

Coating: After the fertilizer is cooled it needs to apply anti-caking agent to it and then it is good to be packed. 

Screening and packaging: The dried NPK fertilizer granules undergo screening to remove particles that do not meet the specified standards, ensuring a uniform product. Subsequently, the qualified fertilizer granules are packaged, usually in bags or bulk form.