A rotary drum dryer is a continuous drying machine widely used in chemical engineering, metallurgy, construction, agriculture, and environmental industries. Below is a detailed introduction covering its structure, working principle, classification, features, and applications.

1. Structural Components

1. Cylinder: This is the main body of the rotary dryer. It's a steel cylinder, typically installed at a slight incline (2°-5°), with internal lifting flights (or "lifters"). The cylinder's rotation tumbles the material and moves it forward.
2. Hot Air System: This includes a heat source and hot air ducts. The heat source can be natural gas, fuel oil, steam, or biomass, used to heat the air. The hot air contacts the material in a co-current, counter-current, or mixed-flow pattern to facilitate heat transfer.
3. Drive Mechanism: This usually consists of a motor, reducer, and gears. The motor drives the gears via the reducer, controlling the cylinder's rotation speed, typically between 3 and 15 revolutions per minute (RPM), to ensure uniform heating and material movement within the drum.
4. Support System: Composed of roller rings, trunnion rollers, and thrust rollers, this system supports the drum and ensures its smooth rotation, minimizing vibration and misalignment during operation.
5. Sealing and Dust Collection: Seals are installed at both ends of the drum to prevent air leaks. The outlet end is typically connected to a dust collector, such as a cyclone separator or bag filter, to capture dust and reduce environmental pollution.
6. Feeding System: Connected to the inlet end of the drum, it typically includes a feed screw, carrier gas inlet pipes, material inlet pipes, a sealing structure, and a screw drive system. Its function is to feed the material into the rotary drum uniformly and consistently.
7. Discharge System: Located at the outlet end of the drum, it usually includes a carrier gas outlet pipe and a discharge box, which are used to remove the dried material and carrier gas.

2. Working Principle

1. Material Conveying and Tumbling: Wet material enters the inclined cylinder from the feed end. As the drum rotates at a low speed, the internal lifters repeatedly scoop up and cascade the material, creating a uniform "curtain of material" inside the drum. This increases the contact area and efficiency between the material and the hot air. Simultaneously, gravity and the drum's rotation move the material toward the discharge end.
2. Heat Exchange Mechanism: Direct-heat rotary dryers use high-temperature gas (400-800°C) flowing in either a co-current or counter-current direction to the material. Heat transfer occurs through conduction, convection, and radiation to evaporate moisture. Indirect-heat dryers, on the other hand, use heat sources like steam, thermal oil, or electromagnetic heat to transfer heat indirectly through the drum wall or internal tubes, preventing direct contact between the material and flue gas.
3. Exhaust Gas Treatment: The moist exhaust gas generated during drying is passed through a dust collector (like a cyclone separator) before being vented. Some systems operate under negative pressure to prevent dust from escaping.

3. Equipment Features

1. Large Processing Capacity: The equipment is suitable for large-scale continuous production, with a single machine's daily output reaching hundreds of tons.
2. Strong Adaptability: It can dry materials with high moisture content, high viscosity, or even heat-sensitive materials. The latter can be dried using a low-temperature operation.
3. High Thermal Efficiency: The design of the lifters and other structures extends the material's residence time in the drum, allowing for a thermal efficiency of 60%–80%.
4. Stable Operation: With a simple structure, low maintenance costs, and a low failure rate, the equipment operates stably and can run continuously.

4. Fields of Application

1. Chemical Industry: Used to dry chemical raw materials such as ammonium sulfate, calcium chloride, fertilizers, and resin pellets.
2. Metallurgical Industry: Can be used to dry ores, mineral powder, and metal powders in preparation for subsequent processes like smelting.
3. Building Materials Industry: Commonly used for drying construction materials like sand, quartz sand, bentonite, and gypsum.
4. Agriculture: Can be used to dry organic fertilizers, reducing moisture content of composted materials to 10%–15%. It can also dry biomass pellets, such as wood chips and straw.
5. Environmental Protection: Used for sludge dewatering in municipal and industrial settings, reducing the moisture content of sludge for easier disposal and reuse.

5. How to Choose a Rotary Drum Dryer

When selecting a rotary drum dryer, you need to consider various factors, including material properties, production needs, equipment performance, and operating costs, to ensure the machine can perform the drying task efficiently and consistently. Here are the key selection criteria:

1. Material Characteristics are Fundamental: The form (e.g., granular, powdered, lumpy), moisture content, viscosity, and heat sensitivity of the material directly influence the dryer selection. For example, for highly viscous materials, you need a rotary dryer with special lifters or an internal breaking mechanism to prevent material from sticking and clumping. For heat-sensitive materials (like food or pharmaceuticals), you should choose a machine that allows for precise temperature control of the hot air to prevent material degradation. Additionally, don't overlook material corrosiveness. If the material is corrosive, the cylinder and internal components should be made of corrosion-resistant materials (like stainless steel) to extend the equipment's lifespan.
2. Determine Equipment Specifications Based on Production Scale: You need to calculate the required drum diameter, length, and rotation speed based on your per-hour material processing capacity and the desired final moisture content. Generally, a larger capacity requires a larger diameter and longer cylinder. However, you also need to ensure the equipment's footprint fits within your facility's layout.
3. Focus on Core Performance Indicators: Thermal efficiency is a critical metric for a dryer's energy consumption. A high-efficiency rotary dryer typically has a thermal efficiency of 60%–80%. You should choose a machine with low heat loss and high hot air utilization to reduce energy consumption. The level of automation is also crucial. A dryer with automatic feeding, discharge, temperature control, and fault alarms can reduce manual operation and increase production stability. Also, check the equipment's sealing performance. Good seals prevent hot air leaks and dust from escaping, ensuring both effective drying and compliance with environmental regulations.
4. Consider Energy Type and Operating Costs: The heat source for a rotary dryer can be coal, natural gas, electricity, or steam. You should choose a heat source based on local availability and cost. For example, natural gas may be more economical and environmentally friendly in some areas, while a coal-fired heat source may have a lower initial cost but could pose environmental emission issues. You must weigh these factors against local environmental policies. Maintenance costs should also be considered. Choosing a dryer with a simple structure and few wearing parts can reduce long-term repair and replacement costs.
5. Choose a Reputable Manufacturer: A quality manufacturer not only provides standard-compliant equipment but can also offer customized designs based on your specific needs. They should also have a comprehensive after-sales service system to provide timely technical support for installation, commissioning, and long-term operation. You can evaluate a manufacturer's quality and service by looking at their production capabilities, customer case studies, and reputation.

In conclusion, when choosing a rotary drum dryer, you need to integrate material characteristics, production needs, performance indicators, and cost control. When necessary, you can ask the manufacturer to conduct a small-scale test to verify the equipment's drying effect on your material before making a final decision.

6. Rotary Drum Dryer Pricing

The price is determined by factors such as product specifications, material of construction, and capacity, based on customer requirements. Please contact our sales team for a specific quote.

7. Company and Product Introduction

Founded in 1997, Tai'an Hongxin Environmental Protection Technology Co., Ltd. is located at the foot of Mount Tai, one of China's most famous mountains. Our facility spans 100,000 square meters, with 66,000 square meters of floor space. We hold an A2 pressure vessel manufacturing license and are ISO9001 certified. We are a high-tech enterprise in Shandong Province, a strategic partner of the Shandong Academy of Agricultural Sciences, and a member of the National Fertilizer Industry Technology Innovation Alliance.

Our team consists of 216 technical staff and over 100 sets of large, precision, and specialized processing equipment. Our professional technical and manufacturing teams provide comprehensive services, including technical consultation, process design, installation, commissioning, personnel training, and full turnkey project solutions. We also guarantee excellent after-sales service. Our products are sold both domestically and internationally, with exports to countries like Indonesia, the UAE, Malaysia, Vietnam, Bangladesh, and Myanmar.