Aluminum oxide rotary kiln Introduction

Aluminum oxide rotary kiln structure

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

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

Rotary kiln bearing housing: The bearing housing serves as the support structure for the kiln's rotating motion and is responsible for holding and guiding the kiln's trunnion bearings. Trunnion bearings are large, heavy-duty bearings that support the weight of the kiln 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 kiln. The bearing housing provides a stable mounting point for the trunnion bearings and ensures proper alignment of the kiln's rotation. It is typically designed to accommodate the axial and radial forces generated during the rotation of the kiln.

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

Kiln Hood Cover: The rotary kiln hood is located at the discharge end of the kiln and provides sealing to retain heat and gases. The rotary kiln 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.

Rotary Kiln Transmission device: The transmission device of the rotary kiln 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 kiln, 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 kiln and the quality of the products being processed. Usually, the rotary kiln 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 aluminum oxide rotary kiln

Design principles for an aluminum oxide rotary kiln involve various considerations to ensure efficient and safe operation while achieving the desired production outcomes. Rotary kilns are used for a variety of high-temperature processes, including the production of aluminum oxide (alumina) from bauxite ore. Here are some key design principles for an aluminum oxide rotary kiln:

Rotational Speed and Inclination: The rotational speed and inclination angle of the kiln affect the material flow, heat transfer, and overall process efficiency. These parameters are determined based on the specific characteristics of the feedstock and the desired reactions.

Gas Flow and Air Supply: Proper gas flow patterns and air supply mechanisms are crucial for combustion and heat distribution. The design should ensure that the fuel-air mixture is well-distributed along the kiln length to achieve complete combustion and prevent hot spots.

Refractory Selection: Refractories are used to line the inner surface of the kiln to withstand high temperatures and chemical reactions. The selection of appropriate refractory materials and their arrangement is essential for maintaining the kiln's integrity and longevity.

Emission Control: Emission of gases and particulate matter is a concern in high-temperature processes. The kiln's design should incorporate mechanisms to capture and treat these emissions, ensuring compliance with environmental regulations.

Cooling and Discharge System: After the desired processes are completed, the material needs to be cooled down before discharge. A well-designed cooling system prevents the material from overheating and ensures safe handling.

Maintenance and Accessibility: Ease of maintenance and accessibility are important design considerations. Components that require regular inspection, cleaning, or replacement should be designed for convenient access.

Safety: Safety features such as temperature monitoring, emergency shut-off systems, and fire prevention mechanisms are integral to the design. The kiln should be designed to minimize the risks associated with high-temperature operation.

Process Automation and Control: Incorporating automation and advanced control systems can enhance the efficiency and consistency of the process. Automation can help in maintaining optimal operating conditions and responding to variations in feedstock and other parameters.

Scale and Capacity: The kiln's dimensions and capacity should be designed to meet the production requirements while ensuring that the system remains stable and efficient.

Quality inspection: Tongli offers magnetic testing and ultrasonic testing, which ensures the quality of all the metal castings and the welding seam.

Specifications of aluminum oxide rotary kiln

Note: *The diameter is the inner diameter, Weight excludes refractory material.

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Industry Knowledge extension

What is the application of calcined alumina?

Calcined alumina, also known as aluminum oxide, is a versatile material with a wide range of applications across various industries. It is produced by heating alumina hydrate to high temperatures, causing it to lose water molecules and become a highly porous and refractory material.

Ceramic Production: Calcined alumina is a key ingredient in ceramic formulations, contributing to the strength, hardness, and thermal stability of ceramic products.

Refractory Materials: It is used in the production of refractory bricks, castables, and other refractory materials due to its high melting point and resistance to thermal shock.

Grinding Wheels and Abrasives: Calcined alumina is used as a abrasive grain in grinding wheels, sandpapers, and other abrasive products due to its hardness and wear resistance.

Catalyst Support: Calcined alumina is used as a support material for catalysts in chemical reactions due to its high surface area and stability.

Substrate for Integrated Circuits: Calcined alumina is used as a substrate material for integrated circuits due to its electrical insulation properties and thermal stability.

High-Temperature Coatings: It is used in high-temperature coatings to provide corrosion resistance and thermal insulation.

Polishing and Lapping: Calcined alumina is used in polishing compounds for precision polishing and lapping of various materials, including metals and optical components.

Filler in Plastics and Polymers: It can be used as a filler or extender in plastics and polymers to improve mechanical properties and reduce costs.

Ceramic Fiber Manufacturing: Calcined alumina can be used in the production of ceramic fibers used for insulation in high-temperature applications.

Oil Refining: It is used as a catalyst support in oil refining processes, such as hydrocracking and catalytic reforming.

Laser Components: Calcined alumina is used in laser components and optical systems due to its high optical transmission and stability.

Dental Ceramics: It is used in dental ceramics for crowns, bridges, and other dental prosthetics due to its biocompatibility and aesthetic qualities.

Insulating Materials: Calcined alumina is used in insulating materials and refractory products to provide thermal insulation in high-temperature environments.

What is the difference between rotary kiln and vertical roller mill?

The rotary kiln and vertical roller mill are both essential pieces of equipment in the cement manufacturing process, but they serve different purposes and are used at different stages of the process.

The rotary kiln is a large cylindrical vessel used for calcining raw materials at high temperatures. It's a core component of the cement manufacturing process and is responsible for transforming raw materials, particularly limestone and clay, into clinker. In the rotary kiln, the raw materials are heated to temperatures exceeding 1400°C (2552°F), where chemical reactions occur that result in the formation of clinker nodules. And they need to be ground into a fine powder to produce cement. This final grinding process is often performed using a vertical roller mill. The clinker is mixed with gypsum and possibly other additives to create the final cement product.

Vertical Roller Mill (VRM): The vertical roller mill is a grinding machine that grinds materials into fine powders, after the raw material is crushed by the crusher, it enters the vertical roller mill. It is typically used for grinding raw materials, clinker, and additives in the cement manufacturing process. The VRM operates by applying hydraulic pressure and vertical force to the grinding rollers, which then grind the materials between the rollers and the grinding table. This grinding process results in a fine powder that is later used as a key ingredient in the production of cement which is important for the subsequent chemical reactions in the rotary kiln.