Drum Dryer

Heating of Drum Dryers

The heating of the drying air is typically done by using gas or light oil burners. The combustion gases are mixed with a portion of ambient air to achieve average drying air temperatures ranging from 600 °C to 900 °C. For thermally robust materials such as quartz sand, the burner flame can directly burn inside the rotating drum. In the case of gentle drying of temperature-sensitive substances such as limestone, clay, bentonite, plastic recyclates, or organic residues and waste materials, combustion chambers are used to ensure that the hot combustion gases are sufficiently mixed with ambient air in the combustion chamber before entering the drum, achieving the desired average drying air temperature.

Combined Drying and Cooling

Allgaier offers combined industrial dryers/coolers in single-shell, double-shell, and triple-shell designs. In all three designs, drying and cooling take place in a single unit, making only one drive and one bearing necessary. Combined drum dryers/coolers are available in three versions: TK, TK+, and TK-D. While the TK type uses ambient air cooling, the TK+ model utilizes the thermal effect of evaporative cooling. The TK-D type is an advancement that combines drying and cooling in a single rotary drum. The TK-D complements the existing systems by offering the capability to cool materials to particularly low temperatures, efficient heat recovery, and resulting energy savings.

Possibilities for Energy Recovery and Efficiency Enhancement  

In order to remain competitive in today's market, it is essential for drum drying processes to incorporate energy recovery and overall efficiency improvement. That is why Allgaier has launched the LeadingEcoSolutions program. Leveraging their extensive experience as a provider of innovative drying systems, Allgaier offers advanced and energy-efficient solution concepts for industrial plants. All possibilities for energy savings are identified in close collaboration with customers to ensure maximum benefits, high quality, and a short payback period.

Application areas for drying devices with drying chambers

Due to their various model variants and robust operational capabilities, industrial dryers of this type can be used in a wide range of applications. The rugged and simple plant technology is primarily employed in the industrial sector of stones/earth or mining. This allows for the processing of different types of rocks and minerals, such as various types of sand, clay, or limestone. Additionally, the drying devices are also utilized in recycling applications, such as recycling glass. By incorporating a special, wear-resistant lining inside the rotary drum dryer, the highly abrasive behavior of recycled glass can be mitigated. Furthermore, the rotary drum units can also be employed in the production of fertilizers or in the thermal treatment of various chemical products.

• Suitability for both coarse and fine-grained solids.

• High resistance to very coarse or heavy solids.

• Minimal effort required for the air supply equipment due to the burner arrangement on the dryer housing.

• Resilience to fluctuations in particle size, moisture, throughput, and drying air failure.

• Low specific electrical energy requirement.

• Ability to use high drying air temperatures with minimal heat loss.

• Low heating energy demand, even at partial load, through adjustment of the exhaust air quantity.

• Easy installation and quick commissioning.

• Resilience to operator errors.

• Ability to operate under challenging climatic conditions.

• Low wear and tear.

Limits of the drum dryers

Despite the numerous applications of various advanced technologies, there are also limitations for these dryer models. The robust design of the dryer can have negative effects on the product in some cases. Specifically, for delicate or temperature-sensitive products, the lifting action, the product conveyance within the dryer, as well as the burner flame or combustion gases in direct contact with the product, can have negative impacts on the material properties. Due to the diverse range of machinery offered by Allgaier Process Technology, these limitations can be addressed using other drying techniques such as fluidized bed dryers, flash dryers, rotary bed dryers, or disc dryers.

What is a drum dryer?

Drum dryers, also known as industrial dryers, are a type of drying equipment used for drying materials such as granules, powders, or pastes. This system consists of a rotating drum, which is equipped with a burner. The drum is typically positioned horizontally and equipped with lifting blades to move the substance through the drum and ensure that it is fully dried by the hot air flowing through the tube.

At what temperatures does a drum dryer operate?

The operating temperature of drum dryers depends on various factors, such as the type of material being dried and the specific requirements of the drying process. Generally, the operating temperatures range from 600°C to 900°C. In some applications, higher temperatures may be required, such as in the calcination of raw materials, where temperatures of over 1000°C can be reached. However, it is important to ensure that the operating temperature always remains within the limits of the material specifications and safety standards to ensure effective drying and safe operation of the drum dryer.

What kind of wear does an industrial dryer experience?

These drying devices undergo a certain degree of wear during their operation. The extent of wear can vary depending on the application, product characteristics, and specific conditions of the drying process. Some factors that can influence wear include the type of product being processed, operating temperature, drum rotation speed, fill level, and the type of internal components.

The internal components of the drum dryer, such as lifting blades, can become worn or damaged and therefore need regular maintenance or replacement to ensure effective drying. The drum itself can also experience wear over time and, in advanced stages, develop cracks or holes that require repair to maintain the safety and effectiveness of the dryer.

How big is a drum dryer?

The size of such an industrial dryer can vary depending on the application and requirements of the drying process. Our drying equipment can be manufactured in a variety of sizes, ranging from small laboratory models to large industrial plants. Depending on customer and application requirements or the available space, Allgaier can perform the appropriate plant dimensioning. The individual residence time of the material inside the drum dryer and the capacity requirements can be evaluated through trial runs in the Allgaier technical center. The data obtained from these experiments are fundamental for the design and sizing of the future production plant. Small drum dryers often have a diameter of only a few centimeters and are designed for laboratory or pilot-scale applications. However, larger drum dryers for industrial applications can have diameters of several meters and lengths exceeding 30 meters.

How long does it take to deliver a drum dryer?

The delivery time can depend on several factors, such as the size and complexity of the dryer, the availability of materials and components, and the manufacturing capacity of the supplier. Additionally, the specific requirements of the customer also play a crucial role in determining the delivery time.

Typically, the delivery time can span several months, as these are custom-made machines tailored to the specific needs of the customer.