Rotary Drum Dryer

Uses of rotary drum dryer

Construction industry

It is used for drying construction and engineering raw materials, mainly sand, river sand, aggregate, yellow sand, cement, clay, blast furnace slag, gypsum powder, etc.

Uses of rotary drum drys in construction industry

Agriculture

It can dry distillers' grains, chicken manure, straw, sawdust, alfalfa, wood chips, wood shavings, chemical fertilizers, etc.

Uses of rotary drum drys in agriculture

Industry

It can be used to dry industrial products or by-products, such as paper pulp, plastic waste, desulfurized gypsum, fly ash, industrial sludge, etc.

Being used for drying industrial products and by-products

Ore dressing industry

It is often used in processing various mineral products after mining. Such as:

Rotary drums drys for processing mineral products

• coal slime, lignite, cinder, coal flotation concentrate, mixed cleaned coal, etc. in the coal industry.
• iron ore, manganese ore, copper ore, laterite nickel powder, tailings, quartz sand, limestone, active lime and other ores, slag powder and slag in the sand and gravel industry.

Characteristics of rotary drum dryers

Long service life. The drying cylinder is made of an advanced alloy steel plate instead of an ordinary steel plate, which increases its wear resistance by 3–5 times and extends its service life by over 3 times.

Low wear and power consumption. With the adjustable tug structure, the tug and the rolling ring are well matched, which greatly reduces wear and power consumption.

Low horizontal thrust. The specially designed stopping wheel greatly reduces the horizontal thrust caused by equipment tilt.

Good stability. Strong anti-overload ability, stable operation of the cylinder and high reliability.

Characteristics of rotary drum dryers

High thermal efficiency, up to 80%. High evaporation intensity can be obtained by high-temperature flue gas.

New type multi-combined material lifting device. It overcomes the "wind tunnel" phenomenon of traditional dryers and effectively reduces coal consumption by about 20%.

No air leakage. Thoroughly solve the difficulty of sealing.

Low production cost. Large processing capacity, less fuel consumption and low drying cost.

Controllable particle size and moisture. When drying slime, the product moisture can reach below 8%, and the particle size can be controlled below 8 mm.

Adjustable output. The design takes into account the production margin. Even if the production volume is reduced, there is no need to replace the equipment.

Zero pollution. The external temperature of the cylinder is balanced and high-quality dust removal equipment is used to control dust pollution, so the exhaust gas can be reasonably converted into water vapor.

How does a rotary drum dryer work?

The wet material is sent to the hopper by the belt conveyor or bucket elevator, and then enters the feeding end through the feeding pipe of the hopper.

The drum of the dryer is a rotating cylinder slightly inclined to the horizontal. Here is a video of how the dryer works from an internal perspective:

The material is added from the higher end, the heat carrier (hot air, flue gas, etc.) enters from the lower end and contacts the material in countercurrent, or the heat carrier and the material flow into the cylinder from the same end together. As the cylinder rotates, the material moves to the lower end by gravity.

When the wet material moves forward in the cylinder, it directly or indirectly receives heat from the heating medium, so that the wet material can be dried, and then sent out through the discharge end.

Shovelling plates are installed on the inner wall of the cylinder. Its function is to pick up and scatter the material to increase the contact surface between the material and the airflow, so as to increase the drying rate and help the material move forward.

The shovelling plates installed on the inner wall of the rotary drum dry

After the heating medium passes through the dryer, a cyclone dust collector or a bag filter is generally required to capture the materials contained in the gas.

What kind of fuel does the rotary drum dryer use?

Coal

Coal, the most versatile and cost-effective fuel, can generate heat of 5,000 kcal/kg.

It is divided into bituminous coal and anthracite. The anthracite is used for most of drying equipment, and dust removal and exhaust gas treatment should be done after the drying process.

Gas

Gas includes all combustible gases such as natural gas, biogas and coal gas. Its heat is about 8,500 kcal/cubic meter with high combustion efficiency, less air pollution and slightly higher comprehensive cost than that of coal.

However, it is limited by the pipeline.

What kind of fuel does the rotary drum dryer use

Biomass pellets

Biomass pellet is a kind of fuel promoted by the government in recent years, which is mainly made of wood chips and straw pellets.

Biomass fuel made of wood raw materials, generally has a low calorific value of 3000~4500 kcal/kg. Its cost is a little more than that of coal, about the same as gas fuel, and is not restricted by pipelines.

How to choose the heat carrier of a rotary drum dryer?

The heating medium of the rotary drum dryer is determined by factors such as the nature of the material to be processed, whether it is allowed to be contaminated, etc.

Flue gas

If the processed solid material is not afraid of high temperature and is allowed to be slightly polluted during the process, flue gas can be used as the heat carrier to obtain a higher volumetric evaporation rate and thermal efficiency.

Hot air

Hot air can be used as the heat carrier if the processed material is not allowed to be contaminated. The air can be heated by steam heaters, electric heaters, other industrial waste gases, etc.

Indirect heating of metal walls

If the dried object is not allowed to be contaminated and diluted by air, the heat should be introduced through the wall of the drum.

The flue gas can be passed directly from the outside of the tube.

The surface heat exchanger (a center pipe, line pipe, sleeve, etc.) can also be installed in the cylinder to transfer heat by the metal wall. The heat carrier may be flue gas, steam, or electric heating.

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