NPK Compound fertilizer Cooler Introduction

Tongli compound fertilizer rotary cooler is a type of industrial equipment used to efficiently cool granular or powdered materials that are composed of multiple nutrients, typically used as fertilizers. The rotary cooler is a device that uses rotating drums or cylinders to facilitate the drying process, the rotary cooler is employed to reduce the moisture content of the fertilizer materials and to cool the material down to the required temperature to facilitate the proceeding process. This is important because moisture regain and extra heat can lead to issues such as caking, clumping, and reduced shelf life of the final product. 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 cooler structure

A compound fertilizer rotary cooler is a type of equipment used in the production of compound fertilizers. Compound fertilizers are fertilizers that contain two or more essential nutrients for plant growth, typically nitrogen, phosphorus, and potassium. These nutrients are combined in specific ratios to provide balanced nutrition to plants.After the compound fertilizer production process, the granules or particles of the fertilizer can be quite hot due to the chemical reactions involved. This is where the rotary cooler comes into play.The structure of a compound fertilizer cooler 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.

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

Cooler Flights: Compound fertilizer cooler flights, also known as "flights" or "lifters," are the inclined, curved structures that are attached to the internal shell of a rotary cooler. A rotary cooler is a device used to remove moisture from materials like powders, granules, and bulk solids through the process of cooling. 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 cooler 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 cooler riding rings allow the dryer to rotate smoothly on its axis and help distribute the cooler's weight. The thickness of the plate under the riding ring is increased to facilitate strength of the shell.

Girth Gear: The Compound fertilizer cooler 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 cooler.

Supporting Device: Compound fertilizer cooler 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 cooler. 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 cooler thrust roller：The thrust roller is a critical part of the Compound fertilizer cooler system. It serves the purpose of supporting the cooler'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 cooler 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 cooler drive system, responsible for transmitting rotational motion and torque from the driving mechanism to the Compound fertilizer cooler 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 cooler. When the pinion is rotated by the drive system, it drives the girth gear, causing the Compound fertilizer cooler to rotate.

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

Cooler Hood Cover: The Compound fertilizer cooler hood is located at the discharge end of the dryer and provides sealing to retain heat and gases. The Compound fertilizer cooler 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 cooler Transmission device: The transmission device of the Compound fertilizer cooler 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 cooler, 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 cooler and the quality of the products being processed. Usually, the Compound fertilizer cooler 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 cooler

Counter-Current Flow: Tongli Compound fertilizer coolers 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.

Heat Exchange Efficiency: The primary purpose of Tongli rotary cooler is to efficiently exchange heat from the hot fertilizer material to a cooling medium. To achieve this, the cooler's design should maximize the contact area between the material and the cooling medium. This is typically done by designing the cooler with internal lifters, baffles, or other features that enhance material movement and mixing.

Airflow and Ventilation: Adequate airflow and ventilation are essential to ensure effective heat transfer and prevent uneven cooling. Tongli design features a balanced and consistent flow of cooling air throughout the rotary cooler. This might involve designing proper inlet and outlet arrangements, along with strategically placed baffles and internal structures to guide airflow.

Material Movement and Residence Time: The residence time of the material inside the cooler directly affects its cooling efficiency. Tongli cooler inner design ensure that the material moves through the cooler at an appropriate rate to achieve the desired cooling without excessive or insufficient residence time. Lifters or flights inside the cooler controls the material's movement and residence time.

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

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

Controlled Discharge: Tongli cooler's design features the controlled discharge of cooled material. This involves design of a discharge chute that prevents material blockages and ensures a consistent flow of cooled fertilizer.

Insulation and Heat Loss Prevention: To maximize energy efficiency, Tongli cooler designed with proper insulation and heat loss prevention measures. This minimizes the amount of heat that escapes the system, reducing the energy required for cooling.

Specifications of compound fertilizer cooler

Note: *The diameter is the inner diameter.

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Industry Knowledge extension

What is the process of fertilizer production line?

When we talk about fertilizer production line, generally we are talking about two kinds of fertilizer production line, organic fertilizer production line and NPK compound fertilizer production line. The process flow of making compound fertilizer production line is the same as the npk fertilizer production line we mentioned in the previous articles. The specific process can vary depending on the type of fertilizer being produced, such as nitrogen-based (N), phosphorus-based (P), potassium-based (K), or compound fertilizers. Here is a general overview of the typical process involved in fertilizer production:

After the raw materials are mixed evenly, all the material will be dumped into the main conveyor belt together and enters the fertilizer drum granulator. What is happening inside the granulator is a process called agglomerate, with the help of the steam, the particles are formed with the aid of rotational motion. Other fertilizer granulation method can also be adopted according to the owner’s specific needs. Also the fertilizer granulation process involves the addition of binders to make the particles stronger together.Water moisture is removed from the granule in order to stabilize the physical property of the fertilizer, and fertilizer rotary cooler is used to cool the fertilizer to temperature required to proceed to the next step.

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.

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.

(Reference: “how is npk fertilizer manufactured” https://npk-fertilizer.com/news/industry-news-201.html)