Desulfurization gypsum rotary dryer Introduction

Desulfurization gypsum dryer is a device that is used to dry desulfurization gypsum, it is an environment-friendly drying equipment that reduces the water content of desulfurization gypsum from more than 30% to less than 12%. Desulfurization gypsum dryer can be used to make drywall slabs, cement, concrete and other building materials.The air and wet gypsum enter into dryer on the same side, use the high-temperature air to obtain high evaporation, and then move to the lower end by gravity, where they are discharged after cooling. The desulfurization gypsum dryer can produce β-hemihydrate gypsum powder, which can be used as cement retarder or building materials.Desulfurization gypsum dryer has reliable operation, large operation flexibility, strong adaptability, large processing capacity, and strong adaptability of materials. It can dry various materials, and the equipment operation is simple and reliable. It is widely used in building materials, metallurgy, chemical industry, cement industry and so on.

Desulfurization gypsum rotary dryer structure

Dryer Shell: The rotary dryer shell is the main body of the dryer, where the material is loaded and rotated. It has a cylindrical shape and is equipped with lifting plates or flights to lift and disperse the material. The drum is heated by hot air or gas that flows through it, either in parallel or countercurrent direction. The drum transfers heat to the material and evaporates the moisture.

Dryer Flights: Rotary 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.

Dryer thrust roller：The thrust roller is a critical part of the rotary 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.

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

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 rotary 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 rotary dryer hood is located at the discharge end of the kiln and provides sealing to retain heat and gases. The rotary 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.

Rotary dryer Transmission device: The transmission device of the rotary 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 rotary 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 rotary 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 desulfurization gypsum rotary dryer

The design principles of a desulfurization gypsum rotary dryer involve the consideration of several key factors to ensure efficient and effective drying of desulfurization gypsum while minimizing energy consumption and achieving the desired product quality. Here are some important design principles to consider:

Rotary Drum Design: The rotary drum is a key component of the dryer. It should be designed to provide adequate residence time for the gypsum particles, allowing them to come into contact with the drying medium for efficient moisture removal.

Material Movement: Consider the movement of the gypsum material within the rotary drum. The design should promote even distribution and agitation of the material to prevent clumping and ensure uniform drying.

Internal Flights or Lifters: Internal flights or lifters inside the drum help lift and drop the material as the drum rotates. They enhance the material movement, facilitate heat transfer, and prevent material buildup on the drum walls.

Heat Transfer Mechanism: Choose an appropriate heat transfer mechanism for efficient drying. Conduction, convection, and radiation are the primary mechanisms involved. The design should optimize these mechanisms based on the characteristics of desulfurization gypsum.

Exhaust System: Design an effective exhaust system to remove moisture-laden air or flue gas from the dryer. Proper ventilation prevents over-drying and maintains consistent product quality.

Control and Monitoring: Implement a control system to monitor and adjust key parameters such as temperature, airflow, and drum speed. This ensures that the drying process remains within the desired operational range.

Product Quality: Consider the impact of drying on the quality of the desulfurization gypsum. The design should aim to achieve the desired final moisture content and particle size distribution while avoiding product degradation.

Safety and Environmental Considerations: Ensure that the design adheres to safety standards and environmental regulations. This includes addressing potential hazards, emissions control, and waste disposal.

Maintenance and Reliability: Design the dryer with maintenance and reliability in mind. Easy access to components for cleaning, inspection, and maintenance contributes to the longevity and efficient operation of the equipment.

Scale and Capacity: Scale the design based on the required capacity of the dryer. Consider factors such as the quantity of desulfurization gypsum to be processed, available space, and future expansion needs.

Economic Viability: Evaluate the cost-effectiveness of the design, taking into account both initial investment and operational expenses. The design should offer a good balance between performance and cost.

Specifications of desulfurization rotary dryer

Note: *The initial moisture is assumed to be 2~6% and final moisture is 1~4%; Inlet temperature of hot air is 150~250 Celsius and outlet temperature is 70~90 Celsius; Production Capacity will vary according to the composition and moisture of the material.

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Industry Knowledge extension

What is the application of dried desulfurization gypsum? 

Dried desulfurization gypsum, also known as FGD (flue gas desulfurization) gypsum or synthetic gypsum, is a byproduct created during the process of removing sulfur dioxide (SO2) emissions from flue gases produced by power plants and industrial facilities. This process is typically accomplished using scrubbers that react with sulfur dioxide to produce gypsum in the form of calcium sulfate dihydrate. Once the gypsum is produced, it can be dried and processed for various applications. Some common applications of dried desulfurization gypsum include:

Construction and Building Materials: One of the primary uses of dried desulfurization gypsum is in the construction industry. It can be used as a component in the production of drywall (gypsum board), which is a widely used building material for walls and ceilings. It provides fire resistance and soundproofing properties.

Cement Production: Dried desulfurization gypsum can also be used as an additive in the production of cement. It serves as a source of calcium sulfate, which controls the setting time of cement and influences its strength and durability.

Agricultural Soil Amendment: Gypsum is used as a soil amendment to improve soil structure and fertility. It can help break up heavy clay soils, improve water infiltration and drainage, and provide a source of calcium and sulfur to the plants.

Manufacturing Plaster and Plaster Products: Gypsum is used to manufacture various plaster products, including decorative moldings, ornamental designs, and medical casts.

Art and Craft Supplies: Dried desulfurization gypsum can be used in art and craft applications, such as sculpture and mold-making.

Animal Bedding: Gypsum can be used as animal bedding material due to its absorbent properties and low dust content.

Waste Stabilization: Gypsum can be used to stabilize and solidify certain types of industrial and hazardous wastes, reducing their environmental impact.

Flue Gas Desulfurization: In a circular economy approach, some of the dried desulfurization gypsum can be used directly in flue gas desulfurization processes, as it is a valuable material for capturing sulfur dioxide emissions.

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.