Sawdust pellets are a type of biomass fuel with high density and high calorific value, it can replace traditional fossil fuels, reduce pollution, and achieve resource recycling. To produce sawdust pellets, drying is usually an indispensable step, because the moisture content of sawdust needs to be controlled at 12-15% before they enter the pellet machine. Too high moisture will cause difficulty in pellet formation and loose pellets, and too low moisture will bring pellet cracking. So, to dry sawdust for making sawdust pellets? What are the considerations during the drying process?

Sawdust drying method

The moisture content of raw sawdust is usually between 30-60%. To produce sawdust pellets, it must be dried first. There are two methods for drying sawdust - natural drying and mechanical drying. Natural drying refers to spreading the sawdust out and allowing water to evaporate under the influence of the sun and wind. However, it is greatly limited by weather conditions, requires long drying times, and consumes manpower. It is only suitable for household sawdust drying, not suitable for large-scale industrial processing. Mechanical drying uses sawdust dryers to reduce the moisture content of sawdust, such as rotary dryers, airflow dryers, and belt dryers. Among them, the most common is the rotary dryer. Compared to other types of sawdust dryers, it has a larger processing capacity, lower energy consumption, and a wider range of applications.

Working principle of sawdust rotary dryer

The sawdust rotary dryer consists of a feeding system, a drum, a heat source, a dust removal system, etc. The drum is an inclined cylinder that rotates around a central axis. Wet sawdust enter the drum through the feeding system and come into full contact with the high-temperature hot air generated by the hot-air furnace. The lifting plate inside the drum continuously lifts the sawdust, making heat exchange between the hot air and the wet sawdust. The moisture evaporates, and the sawdust with the target moisture content are discharged from the drum. The exhaust gas is purified by the dust removal system and then discharged. 

Advantages of rotary sawdust dryer

1. High thermal efficiency

The drum adopts a self-insulating design, it can reduce energy loss and increasing thermal efficiency by 50%.

2. Large processing capacity

We offer both single-cylinder and triple-cylinder dryers. According to your processing capacity, we can customize sawdust dryers from 1 to 20 tons per hour. The machine can work continuously for 24 hours, suitable for large-scale industrial processing.

3. Wide applications

Rotary sawdust dryer is suitable for various materials, such as wood chips, straw, okara, brewer's grains, chicken manure, coco peat, sand, sludge, etc.

4. Flexible fuel options

The fuel can be biomass, natural gas, coal, diesel, steam, or other inexpensive and readily available fuels.

5. Automated control

The machine is equipped with an automated control system, it can intelligently senses and promptly adjusts the temperature and humidity inside the drum to ensure even drying of the sawdust. The moisture content of the finished product can be adjusted as needed.

Precautions for drying sawdust

1. Temperature control

Set an appropriate drying temperature to ensure a steady temperature rise, rather than setting it too high. If the temperature of the dryer is set too high, although the temperature rises quickly, only the surface will be dry while the inside remains wet.

2. Material placement

Load material according to the processing capacity of the dryer during design, and do not add too much at once. If too much sawdust is added, it will cause the internal space of the dryer to become crowded, preventing hot air from circulating fully among the sawdust. This will prevent some sawdust from contacting sufficient hot air, thereby affecting the drying effect. At the same time, the placed sawdust should be of uniform size, otherwise smaller pieces of sawdust will be dried first, but larger pieces will not meet the requirements, affecting the drying quality.

3. Daily maintenance

Sawdust dryer needs to be cleaned regularly. During use, dust and debris accumulate, if not cleaned for a long time, may affect the normal operation of the equipment, clogging the pipes and filters. Also, after long time use, parts of the equipment may wear out, lubrication is required to reduce wear and extend its service life.                                                                                                                                                            

Conclusion

In the process of making sawdust pellets, drying is an indispensable step to ensure the quality of the pellets. In large-scale industrial production, rotary sawdust dryer is the most common type of drying, it has advantages like high processing capacity, high thermal efficiency, and wide application. When using a sawdust dryer to dry sawdust, attention should also be paid to parameter control and daily maintenance, which can ensure the stability of finished product quality and prolong the service life of the equipment. Zhengzhou Jiutian is a leading manufacturer of sawdust drying and pellets production lines, it has rich experience and advanced technology. We have successfully implemented sawdust drying and pelleting production line projects in dozens of countries across Europe, Asia, and the Americas. If you are interested in our equipment, please feel free to inquire.