Drum kiln

Types of drum kilns

A drum kiln is a large round furnace used in the construction industry to powder lime from limestone rocks. In the broader sense, drum kilns are large cylindrical furnaces used to heat materials to high temperatures in various industrial processes, including the chemical, cement, and ceramics industries. The design of drum kilns may slightly differ to cater to specific industries and functions.

• Cement drum kiln:

  As the backbone of the cement industry, the cement drum kiln is the largest and most pivotal heating device. The widespread rotary drum kiln, on the other hand, is an oven with a horizontal rotation. The materials, when moving forward in an annular space between the furnace body and the kiln support, are heated, calcined, and sintered by hot gas that moves in the opposite direction. The products of the rotary drum kiln are cement clinker.

• Rotary drum kiln:

  Typically, chemical reactions that produce gases, such as steam, ammonia, carbon dioxide, sulfur dioxide, nitrogen oxides, and other volatiles, occur at high temperatures, such as >1000°C. The rotary drum kiln can provide the high thermal energy required for the reaction. The kiln's long residence time allows continuous chemical reactions. Drum kilns also have the advantage of being scalable. Rotary drum kilns can be operated on a large scale to satisfy industrial production requirements. On the other hand, they can also be used on a small scale for research and development or, at times, for experimental purposes.

• Active lime drum kiln:

  The active lime kiln has two to three parts: the feeding device, the burning device, and the discharging device. The feeding device of the active lime drum kiln usually has an air lock or a lock hopper. The burning device includes the pre-heating zone, the calcination zone, and the cooling zone. The burning device also includes a combustion chamber where the fuel burns and the limestones rotating and rolling in the furnace get heated. The discharging device usually has a draw- off gate or a feeder. Sometimes, there are water sprinklers in the discharging device, which gives the quick lime a hydrated form after going through the kiln.

• Indirect heated drum kiln:

  In an indirectly heated kiln, the material is heated by heat radiated from the kiln wall. This type of kiln is suitable for materials that cannot be in contact with combustion gases.

Specification and Maintenance of Drum Kilns

Specification

The specifications are different depending on the type, material, and application for which the drum kiln is designed. The following are some general specifications to note.

• Capacity: The capacity of a drum kiln is usually described in tons per batch. For a smaller drum kiln, the capacity could be around 2 to 10 tons per day. Larger rotary drum kilns have capacities in the range of hundreds to thousands of tons per day.
• Temperature: The temperature of a drum kiln varies according to the material being processed. An indirect heated drum kiln can reach temperatures of about 800 to 1,000 degrees Celsius. Rotary drum kilns can reach over 1,500 degrees Celsius.
• Length and Diameter: A typical drum kiln will have a length of 3 to 7 meters and a diameter of 1 to 3 meters. The larger dimensions of a rotary kiln can go as far as 50 meters in length and 5 meters in diameter.
• Air Flow: In a drum kiln used for charcoal production, the air flow is usually described in cubic meters per hour. A small-scale kiln may have an air flow of 5,000 to 25,000 cubic meters per hour. In contrast, lớn systems like rotary kilns can have a much higher air flow rate, around 100,000 to 200,000 cubic meters per hour or more.

Maintenance

The key to a drum kiln's longevity and optimal performance lies in regular maintenance and repairs. The most vital pieces are the support rollers, thrust rollers, and bearings. They need to be kept lubricated and well aligned all the time. Take time out for routine inspections to spot any frequently worn parts. Make the necessary adjustments to ensure a tight seal between the kiln and cooling drum, feeding, and discharge ports. This will also help reduce gas loss, improve energy efficiency, and keep the operating costs down.

For water cooling drum kilns, inspect the water pipes and valves for any signs of leakage. Seal any leakages right away to prevent any kind of water loss. If there is a cooling system fan, check the belts and make sure they are securely tightened. The failure of a cooling fan could result in serious damage to the entire kiln system. Inlet and outlet dust collators should be checked frequently for blockages and cleaned regularly to ensure effective dust collection and ventilation.

Because a kiln can reach such high temperatures, the insulating materials are bound to wear down over time. So, look out for any signs of damage and replace them as needed to keep heat loss to a bare minimum and improve energy efficiency. Any misalignments can lead to the uneven wear of the kiln’s surfaces or the support structures. So, alignment should be checked periodically and adjusted as needed. Also, do routinely calibrate the temperature and control systems. This will ensure that the kiln operates according to specifications with the right temperature and flow controls.

Scenarios of drum kilns

The versatile drum kiln is extensively used in diverse industries for various application scenarios:

• Cement production:

  The cement industry benefits immensely from the drum rotary kiln. Not only is it responsible for efficiently calcining materials like limestone and clay, but it also plays a vital role in producing quicklime and cement through the focused heating of limestone.

• Metallurgy:

  Rotary drum kilns are commonly used in metallurgy to calcine and oxidize ores and materials. For instance, in iron metallurgy, they can be used for the oxidation of iron ore pellets and dewatering of iron ore. Additionally, rotary drum kilns are suitable for treating non-ferrous metals like copper, zinc, and nickel.

• Construction materials:

  Besides cement, rotary drum kilns can produce other construction materials such as lime, dolomite, and gypsum. These materials are essential for producing high-quality cement and are commonly used in construction projects.

• Chemical production:

  The chemical industry relies heavily on rotary drum kilns for the production of various chemicals. The drums are used to calcine materials like petroleum coke and activated carbon, which are essential for producing chemicals used in different industries.

• Environmental protection:

  Drum kilns play a crucial role in environmental protection by treating hazardous waste. They help in the safe disposal of waste materials by incinerating them at high temperatures, thus reducing their volume and eliminating harmful substances.

• Food industry:

  Drum kilns are widely used in the food industry, particularly for roasting nuts and seeds. The rotating drum evenly spreads the materials, ensuring uniform roasting. Additionally, flavors and spices can be added during the process to enhance the taste.

How to choose a drum kiln

When purchasing a drum drying machine, buyers should consider the following parameters.

• Production capacity: The production capacity of a drum dryer is usually expressed in terms of the amount of material dried per hour or per unit of time. To select a suitable production capacity, buyers should first estimate their own food drying needs and then consider factors such as material characteristics, processing volume, and available time.
• Drum diameter and width: For large-scale industrial drying needs, buyers may need to choose a dryer with a larger drum diameter and width to meet higher processing volumes. Consider the available factory space and select equipment that can be accommodated within the spatial constraints. Also, ensure that the necessary installation and adjustment equipment is available to install and adjust the drum dryer properly.
• Heat source type: The heating method of the drum dryer has an important influence on the drying efficiency and energy consumption. Buyers need to consider the suitability of their production processes and the available heat sources.
• Motor power: Buyers need to choose a motor with enough power to ensure the normal operation and stability of the equipment. Ensure that the motors used in the equipment can meet the required power and torque values at the optimal operating speed.
• Manufacturing material: The manufacturing material directly affects the service life and reliability of the equipment. Buyers need to choose a drum dryer whose manufacturing materials are corrosion-resistant, heat-resistant, and wear-resistant.

By taking the above factors into consideration, buyers will be able to choose a drum dryer that is the right fit for their needs.

Drum kiln FAQ

Q1: What is the difference between a drum kiln and a rotary drum kiln?

A1: Both drum kilns and rotary drum kilns use a cylindrical vessel. However, the movement of materials in rotary drum kilns may vary with a rotary drum kiln incorporating a rotating shaft. Conversely, the drum kiln may have a static or slightly rotating cylindrical chamber.

Q2: What industries utilize drum kilns?

A2: The drum kiln is widely used in several industries. Its uses include the production of cement, limestone, charcoal, activated carbon, and other materials. Besides, industries often collaborate with factories that specialize in drum kilns. This ensures that the company will know about the drum kiln, its workings, and how to further enhance its production capacity.

Q3: Can a drum kiln be automated?

A3: Yes, modern drum kilns can be automated. Automation can improve control over the heating process, enhance production efficiency, and reduce labor intensity.

Q4: What are the environmental impacts of a drum kiln?

A4: The drum kiln may produce emissions, such as SO2, CO2, and particulates. Appropriate air pollution control equipment should be installed to manage them.