Compound fertilizer granulator Introduction

Tongli NPK compound fertilizer granulator is a machine or equipment used in the fertilizer production line to produce granulated fertilizer blends that contain three key nutrients: nitrogen (N), phosphorus (P), and potassium (K). The granulation process involves mixing and combining the individual nutrient components with other additives and binders to create a homogeneous mixture. This mixture is then processed through the granulator, which forms the mixture into small granules. These granules are easier to handle, transport, and apply to agricultural fields compared to powdered or bulk fertilizer materials. NPK compound fertilizer granulators can come in various forms, including rotary drum granulators, disc granulators, pan granulators, and more. The choice of granulator type depends on factors such as the desired granule size, production capacity, and the specific characteristics of the raw materials being used.

Compound fertilizer granulator structure

The structure of a compound fertilizer granulator 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.

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

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

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

Supporting Device: Compound fertilizer granulator 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 granulator. 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.

Thrust roller：The thrust roller is a critical part of the granulator system. It serves the purpose of supporting the granulator'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 granulator and is attached to the shell, it consists of a central shaft or journal and a roller assembly.

Granulator pinion: The pinion is an essential part of the rotary granulator drive system, responsible for transmitting rotational motion and torque from the driving mechanism to the rotary granulator 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 rotary dryer. When the pinion is rotated by the drive system, it drives the girth gear, causing the rotary granulator to rotate.

Granulaotr bearing housing: The bearing housing serves as the support structure for the granulator's rotating motion and is responsible for holding and guiding the granulator'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 rotary granulator. The bearing housing provides a stable mounting point for the trunnion bearings and ensures proper alignment of the granulator's rotation. It is typically designed to accommodate the axial and radial forces generated during the rotation of the granulator.

Granulator Hood Cover: The rotary granulator hood is located at the discharge end of the granulator and provides sealing to retain heat and gases. The rotary granulator operates witht the steam pipe, therefore Tongli implied SS304 lining plate and ceramic felt both in the front and back end to prevent heat leakage.

Rotary granulator transmission device: The transmission device of the rotary granulator 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 rotary granulator, 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 granulator and the quality of the products being processed. Usually, the rotary granulator 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 granulators 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 granulator. 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 granulator 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.

Spraying Mechanism: Granulating liquids, such as binders or solutions, are sprayed onto the material as it tumbles within the drum. The spraying mechanism should ensure even distribution of the liquid across the material bed to facilitate granule formation without causing uneven wetting or accumulation

Binder Delivery System: A proper binder delivery system should be designed to precisely control the amount and rate of binder application. This can involve pumps, nozzles, atomization devices, and other components to evenly distribute the liquid over the material.

Specifications of compound fertilizer dryer

Note: *The diameter is the inner diameter.

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Industry Knowledge extension

What is fertilizer production plant?

A fertilizer production plant is a facility where various types of fertilizers are manufactured. Fertilizer production plants play a crucial role in modern agriculture.The process of fertilizer production involves several key steps:

Raw Material Preparation:The primary raw materials used in fertilizer production are nitrogen (N), phosphorus (P), and potassium (K), along with secondary and micronutrients. These materials can be derived from natural sources like minerals, as well as synthetic sources. Raw materials need to be processed to create a usable form for the production process.

Mixing and Blending: Different raw materials are mixed and blended in specific proportions to create the desired fertilizer formulation. The ratios of nitrogen, phosphorus, and potassium, often represented as N-P-K ratios, are determined based on the type of crops and their nutrient requirements.

Granulation: Many fertilizers are produced in granulated or prilled forms. This involves forming small solid particles that are easy to handle, transport, and apply to fields. Granulation processes can involve compacting and shaping the fertilizer mixture.

Drying: After granulation, the fertilizer particles are typically dried to reduce moisture content, preventing clumping and ensuring product stability.

Cooling: The dried fertilizer is cooled to prevent the risk of overheating and to enhance the handling and packaging process.

Sizing and Screening: The cooled and dried fertilizer particles are often screened to separate them into different size fractions, ensuring uniformity in particle size.

Packaging: The final fertilizer product is packaged into bags, sacks, or bulk containers for distribution and sale to farmers and agricultural businesses.

Quality Control: Throughout the production process, quality control measures are taken to ensure that the final fertilizer product meets the required standards for nutrient content, physical properties, and safety.

(Reference: "What is the compound fertilizer production process" https://npk-fertilizer.com/news/industry-news-197.html)

What is the difference between rotary dryer and rotary kiln?

Rotary dryer: A rotary dryer is used to remove moisture from materials, such as minerals, ores, chemicals, food products, and biomass. The primary purpose of a rotary dryer is to reduce the moisture content of the material through the application of heat and the movement of the material within the drum. In a rotary dryer, materials are fed into the rotating drum, and hot gases or air are introduced to evaporate the moisture. The material is tumbled and agitated as it moves through the drum, allowing for efficient drying. Rotary dryers operate at elevated temperatures to facilitate drying, the temperatures used are generally lower compared to those in rotary kilns. Rotary dryers are used in industries such as agriculture, mining, chemicals, and food processing to remove moisture from bulk solids, powders, and other materials.

Rotary Kiln: A rotary kiln is designed for high-temperature processes, such as calcination, sintering, pyrolysis, and other thermal treatments. It's used to process raw materials or products at elevated temperatures, often in a controlled atmosphere, to bring about physical or chemical changes in the material. In a rotary kiln, materials are typically fed into one end of the kiln and gradually move towards the other end. The kiln is heated to very high temperatures, and the material undergoes chemical reactions, phase changes, or thermal treatments as it progresses through the kiln. Rotary kilns operate at much higher temperatures, often reaching well over 1000 degrees Celsius (1800 degrees Fahrenheit), depending on the specific process. These high temperatures are necessary to achieve the desired chemical or physical transformations in the material. Rotary kilns are used in industries such as cement production, lime calcination, metallurgy, and waste incineration. They are designed for processes that require high-temperature reactions, phase changes, or material transformation.