indirectly heated drum dryers

difference between rotary dryer and drum dryer

difference between rotary dryer and drum dryer

Many customers cannot tell the difference between rotary dryer and drum dryer, so Unique will explain it. Rotary dryer is a kind of drying machine and has wide application in the mining industry. It can be divided into direct heat rotary dryer and indirect heat rotary dryer. The rotary dryer is suitable for drying metal and non-metallic materials, clay in the cement industry and coal slime in the coal mining industry. It has the features of high production efficiency and convenient operation and the advantages of reasonable structure, good manufacturing, high output and low energy consumption. Drum dryer is a kind of traditional drying machine with reliable operation, big operational flexibility, high adaptability and big processing ability and it is widely used in such fields as metallurgy, building material, chemistry, fertilizer, sand, clay and kaolin. It has high extension ability and the designing of this machine takes into consideration the production allowance, so that even the output increases within a narrow range, no equipment changing is needed. This equipment adopts self-aligning tug structure and the combination of the tug and rolling ring is good, thus greatly reducing the abrasion and consumption of kinetic energy. The overload-proof ability is high and the drum is stable in operation and high in reliability.

indirect drying vs. direct drying

indirect drying vs. direct drying

When it comes to drying bulk solids, rotary dryers are often the industrial drying equipment of choice. Their robust build, reliability, and aptitude for handling variation in feedstock makes them an ideal choice for efficiently drying bulk solids of nearly all types.

When referring to rotary dryers, its usually safe to assume that a direct-fired rotary dryer is the topic of discussion. Direct dryers are used more frequently than their indirect counterparts, because of the efficiency they offer. And while direct fired rotary dryers are most often the selected drying method, indirect rotary dryers are a valuable alternative for specific processing needs.

Direct-fired dryers rely on direct contact between the material and process gas to efficiently dry materials. Efficiency is further increased by the addition of lifting flights affixed to the internal walls of a direct rotary dryer. These flights lift the material, carrying it over and cascading it through the stream of process gas, in order to maximize heat transfer between the material and drying medium.

Indirect dryers rely on the heat emanating from the drums shell to dry the material via conduction and radiation. Subsequently, indirect dryers would not benefit from the addition of lifting flights, since there is no process gas moving through the drum. Furthermore, because the furnace exhaust is kept separate from the process gas, indirect dryers have the added benefit of requiring less exit gas treatment.

Unlike their direct-fired counterparts, which are typically constructed of carbon steel, indirect-fired rotary dryers are constructed using a high temperature alloy, in order to maintain the integrity of the drum, despite the constant exposure to high temperatures that the shell must endure.

Direct fired rotary dryers account for the lions share of bulk solids drying applications, and are used throughout a multitude of industries, including fertilizer and agriculture, mining and minerals, specialty chemicals, and more. They offer heavy-duty processing and consistent reliability.

Indirect-fired rotary dryers are better suited for niche applications. Indirect-fired dryers are ideal for processing dusty, fine materials, or materials that cannot be exposed to oxygen or combustion gases during processing. This is commonly seen with food grade materials, highly combustible materials, organics such as grains and pulps, and fine materials such as pigments.

FEECO has been a leader in the field of thermal processing for over 60 years, providing both direct and indirect rotary dryers to meet the varying demands of a wealth of industries. For more information on direct or indirect rotary dryers, contact us today!

rotary dryers

rotary dryers

Weve built a reputation on building the best rotary dryers in the industry. All of our dryers are custom designed to suit the unique processing needs of your material. Whether you require low or high inlet temperatures, short or long residence times, counter current or co-current flow, FEECOs design team can design a rotary drum dryer for your application.

Rotary dryers are a highly efficient industrial drying option for bulk solids. They are often chosen for their robust processing capabilities and their ability to produce uniform results despite variance in feedstock.

The drum is positioned at a slight horizontal slope to allow gravity to assist in moving material through the drum. As the drum rotates, lifting flights pick up the material and drop it through the air stream in order to maximize heat transfer efficiency. When working with agglomerates, the tumbling action imparted by the dryer offers the added benefit of further rounding and polishing the granules.

All FEECO equipment and process systems can be outfitted with the latest in automation controls from Rockwell Automation. The unique combination of proprietary Rockwell Automation controls and software, combined with our extensive experience in process design and enhancements with hundreds of materials provides an unparalleled experience for customers seeking innovative process solutions and equipment.

Rotary dryers are known as the workhorse of industrial dryers. They are able to process a wide variety of materials, and can lend a hand in nearly any industry requiring industrial drying solutions. Some of the most common industries and materials in which rotary dryers are employed include:

Unlike direct dryers, indirect dryers do not rely on direct contact between the material and process gas to dry the material. Instead, the rotating drum is enclosed in a furnace, which is externally heated. Contact with the heated drum shell is what dries the material.

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Our rotary dryers are built to the highest quality standards, with longevity in mind. The best part about buying a FEECO rotary dryer, is that you get the security of knowing your equipment is backed by over 60 years of experience, material and process knowledge, and a proven track record.

indirectly heated tube drum dryers- bttner energy & drying

indirectly heated tube drum dryers- bttner energy & drying

Bttner's indirectly heated tube drum dryers are specifically designed to work in combination with cogeneration systems (CHP). They function as reliable and efficient dryers for wood flakes,DDGS, Corn gluten feed and other finely dissolved and free-flowing wood material, biomass products and bulk solids.

A product designated for drying comes in through an air-tight rotary valve and into a rotating single-pass dryer drum with installed tube bundle. The product then flows through the heated tube bundle, which turns with the drum casing and warms the product. In doing so, the water contained in a product is evaporated into the dryer air, which is preheated by heat exchangers. At the end of the dryer drum, the dried product is separated in a drop box and discharged through an air-tight rotary valve. Warm and moist dryer air is extracted and dedusted in cyclones or bag filters.

indirect rotary dryers | idreco

indirect rotary dryers | idreco

Indirect rotary dryers differ from convective-direct dryers in that heat is transferred to the wet product by conduction and radiation through the cylinder wall or through a series of tubes located circumferentially to the cylinder.

Carbon black coming from the reactor, which is not part of Idreco technology, is fed to a wet pelletizer where water together with molasses are added to form wet pellets. Molasses are used as a binder for beading / pelletising of carbon black particles, as required to obtain carbon black with desired characteristics.

Annular chamber receives hot gases produced in a combustion chamber which recover as heating medium tail gas coming from carbon black reactor. Tail gas has poor heating value (around 700 kcal/Nm3) and combustion chamber is provided with honeycomb wall appositely studied to assure the complete combustion.

To increase the thermal efficiency, a side stream of the heating gas can enter in the rotary dryer cylinder through a snorkel: gas flows in countercurrent with the pellets and is discharged at the feed head side together with the evaporated water vapour.

Hot gases generated inside the combustion chamber are conveyed inside concentric rows of tubes installed circumferentially to the cylinder. Along the length of the tubes, intermediate supports are provided.

Flue gases leave the cylinder on the wet product feed side and are partially recycled inside the combustion chamber to reduce fuel consumption and partially discharged to atmosphere with eventual heat recovery.

how do indirect heat rotary dryers work?

how do indirect heat rotary dryers work?

Because the heat source is separated from the processed material, air velocities within the rotating drum are kept to a minimum or are non-existent. Heat transfer is accomplished through conduction of the heat from the shell to the product and radiation of heat off the shell. The internal flighting inside the rotating drum is specially designed to gently roll the material being processed, constantly exposing new material to the heated shell to maximize the heat transfer process. Flights are designed to avoiding showering the product as that actually decreases heat transfer due to the minimum airflow inside the shell.

indirect rotary dryers - vulcan drying systems

indirect rotary dryers - vulcan drying systems

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Built for performance and reliability, Vulcan Indirect Rotary Dryers produce quality and replicable drying results. Our Indirect Rotary Dryers are one of the most versatile industrial dryers on the market. Our modular approach allows you to pick the dryer size, flight arrangement, burner and air pollution control equipment to best suit your unique project.VulcanIndirect Rotary Dryers are built to rigorous safety and performance standards because they are 100% designed, manufactured and tested in the USA.

Vulcan Indirect Rotary Dryers rely on the heat transferred through the drums shell to dry the material via conduction and radiation to reduce the materials moisture content. Indirect drying allows you to tightly control the processing environment, an ideal characteristic when working with materials that can be combustible or where higher temperatures are required to remove bound water. Our indirect dryer units can have tumbling flights (optional) and an air stream heat exchanger (optional) mounted in the combustion chamber stacks to utilize waste heat to heat sweep air and increase drying efficiency.

Vulcan's Indirect Rotary Dryers come in standard sizes ranging from 3 diameter by 15 long to 8diameter by 60 long. Whether you have a small 1TPH project or a large 200TPH project, we can construct your dryer to fit your project.

Vulcan's Indirect Rotary Dryers are constructed from a variety of materials depending on your application. Each standard dryer has four options for you to choose from, but we can construct your dryer from any material that you

Your indirect rotary dryer can be customized with a number of flight options from standard to aggressive (or a combination). Knock out boxes can be added for your controls, insulation and wraps to better control temperature and an external finish paint to keep your dryer looking new for years.

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