Drying Machine

One. Purpose of the rotary drum dryer

Tumble Dryer (rotary dryer), commonly referred to as the dryer, is a dryer for handling large quantities of materials. Due to its reliable operation, flexible operation, strong adaptability, and high capacity, it is widely used in metallurgy, building materials, food, light industry, chemicals, coal, and mining industries. The rotary drum dryer is generally suitable for granular materials and can also be used to dry sticky paste-like materials or materials with high moisture content by partially blending them. Its advantages include high production capacity, wide applicability, low flow resistance, a wide range of operational fluctuations allowed, and ease of operation. It is commonly used for drying sand, mineral powder, coal sludge, chicken manure, cow dung, and more.

Section 2: Structure and Principle of the Drum Drying Machine

1. Structural Diagram: The rotary drum dryer consists of the following parts: 1. Drum body; 2. Front roller ring; 3. Rear roller ring; 4. Gear; 5. Stop roller; 6. Drag roller; 7. Small gear; 8. Discharge section; 9. Elevating plate; 10. Reducer; 11. Motor; 12. Hot air duct; 13. Feed chute; 14. Furnace body, etc. Additionally, gas generators, combustion chambers, or auxiliary equipment such as hoists, belt conveyors, feeders, cyclone dust collectors, and induced draft fans can be designed according to customer requirements.

2. The operating principle of the rotary drum dryer:

Dry wet material is conveyed to the hopper by a belt conveyor or a bucket elevator, then it enters the feeding end through the feeding pipeline via the hopper's feeder. The slope of the feeding pipeline must be greater than the natural angle of repose of the material to ensure smooth flow into the dryer. The drum dryer's drum is a rotating cylinder slightly inclined from the horizontal line. Material is added from the higher end, while the heat carrier enters from the lower end, contacting the material in a countercurrent manner; there are also instances where the heat carrier and material flow together into the drum. As the cylinder rotates, the material moves under gravity to the lower end. During the forward movement of the wet material within the drum, it receives direct or indirect heat supply from the heat carrier, allowing for drying. The dried material is then discharged at the outlet end via a belt conveyor or a screw conveyor. Scrapers are mounted on the inner wall of the drum, which function to lift and scatter the material, increasing the contact surface with the airflow to enhance drying speed and promote material movement. Heat carriers are typically hot air, flue gas, etc. After passing through the rotary drum dryer, a cyclone dust collector is generally required to capture the material carried by the gas. To further reduce the dust content in the exhaust gas, a baghouse dust collector or a wet dust collector should be used before discharge.

Section 3: Technical Parameters of the Rotary Drum Drying Machine

IV. Characteristics of Various Drying Equipment: When selecting rotary drum drying equipment, it's essential to first understand the characteristics of the drum dryer.。

1. The rotary dryer's adaptability to the drying material, such as whether it can achieve the required dryness level of the material and the uniformity of the dried product.

2. Does the drum dryer damage the quality of the product? Some products require maintaining their crystalline shape and color, while others must not deform or crack during the drying process.
3. This is the main technical and economic indicator for the drum drying equipment.
Five, Selection of Heat Carriers: The choice of heat carrier and its high temperature depend on the properties of the solid material being processed and factors such as whether it allows contamination.

1) If the solid material to be processed is not afraid of high temperatures and is not a product, it can be allowed to be slightly contaminated during the processing. In such cases, a hot air furnace or flue gas can be used as a heat carrier, resulting in a higher volumetric evaporation rate and thermal efficiency. For example, in the drying of imported materials with high moisture content, when the gas inlet temperature is 300 degrees, the dryer has a volumetric evaporation rate of 5 kg/M3/h and a thermal efficiency of 30% to 50%; if the gas inlet temperature is 500 degrees, the volumetric evaporation rate increases to 35 kg/M3/h, with a thermal efficiency of 50% to 70%. Therefore, for drum dryers processing materials like ore, sand, coal, and phosphated calcium sulfate, the drums can be equipped with a combustion furnace that directly produces flue gas. The gas fuel can be coal, oil, natural gas, liquefied gas, and so on.

2) If the materials being processed cannot be contaminated and require high temperatures, our company's new gas generator can be used as a heat carrier. If local requirements are very strict and sanitation is a priority, choosing a gas generator would be an even better option. The gas generator is at least 20% more efficient than a combustion furnace in terms of both energy and labor. Typically, one worker can operate a gas generator, and it does not require constant coal addition. Additionally, the gas generator can be used and stopped as needed, remaining idle for up to 10 days and still be ready for use upon restarting.
3) There are also indirect heating methods, where heat is transferred from the metal walls to the material being dried, such as external heating drum dryers.
4) If the dried substance is not to be contaminated and should not be diluted by air, heat should be transferred through the drum wall. In this case, the drum is loaded in a brick chamber with flue gas passing through the outside. It can also carry a central pipe or a series of pipes, sheath tubes, etc., as surface heat exchangers inside the drum, utilizing heat transfer through metal walls. The heat carrier can be flue gas, steam, or electrically heated. Only clean gas is used to carry away the evaporated moisture from the dried material.
In summary, the selection of the heat carrier should be based on material requirements and local natural advantages; otherwise, it may affect production efficiency and economic benefits.