Wood pellets are a type of biomass fuel made from compressed sawdust and other waste wood materials. They are cylindrical in shape, typically 6-10mm in diameter and 10-30mm in length. Wood pellets produce almost no carbon dioxide when burned, making them one of the most environmentally friendly fuels. Liyang Rongda Machinery Co., Ltd. will explore the production process of wood pellets with everyone (with step-by-step images).

1. Raw Material Collection

There are many raw materials for wood pellets, such as wood, grain, alfalfa, corn husks, peanut shells, straw, grass clippings, garden waste, forest and agricultural waste, etc. These wastes can be converted into efficient biomass fuel after proper treatment.

2. Chipping and Crushing Process

The raw materials used for making wood pellets must be broken down into very small pieces. Users typically use wood chippers to cut logs into pieces of 2.5 cm (0.98 inches) or smaller, then use hammer mills to further crush and cut these smaller pieces into very fine particles, reducing the raw material size to 5 mm (0.20 inches). Some users choose pre-processed wood chips, which allows them to skip this step.

3. Raw Material Drying Process

Drying the raw material to the appropriate moisture content is crucial for manufacturing high-quality pellets. Before pelletizing, the moisture content of the raw material must be maintained at approximately 10%-20%. For small batches of pellets, the raw materials can be naturally dried by placing them in sunlight for at least 24 hours; for larger batches, a dryer can be used to dry the raw materials to the required moisture content.

4. Screening, Iron Removal and Impurity Removal

Wood chip raw materials may contain impurities such as stones or metal. If these impurities enter the pelletizing chamber of the pellet machine, they are likely to cause mold blockage or wear of the pellet machine. Therefore, screening, iron removal and impurity removal must be performed before the raw materials enter the wood pellet machine. Liyang Rongda Machinery provides professional screening and cleaning equipment to ensure the purity of the raw materials.

7. Pellet Production Process

The most commonly used equipment for pelletizing includes ring die pellet mills and flat die pellet mills. Liyang Rongda Machinery specializes in producing biomass pellet machines. Ring die pellet mills work by using ring dies and rollers to compress the raw materials into the ring die holes and continuously extrude them to the outer end. Flat die pellet mills work by having the roller and flat die move relatively to compress and compact the material into die holes, which are then cut through the die holes to form pellet-shaped products. During pelletizing, it's important to ensure uniform feeding to prevent machine blockage caused by excessive feeding speed.

8. Screening Process

Not all pellets can be well formed during the compression process. Some pellets may scatter or break during compression. Usually, a filter screen with the same aperture as the wood pellet size is used to shake or screen to remove deformed pellets. We provide professional screening equipment to ensure product quality.

9. Pellet Cooling

When formed pellets exit the pellet machine, the pellets themselves will be very hot and release water vapor, so they must be cooled and dried. Cooling makes them harder. The most common method is natural air drying, or pellets can be cooled from 80-90°C to room temperature through a cooling machine. We provide professional cooling equipment.

10. Packaging and Storage

After cooling, the pellets are transported to packaging equipment, packed and stored in dry places. Pellet storage must be kept away from moisture, as if the pellets absorb moisture, it will affect their combustion performance. We provide professional packaging equipment to ensure complete product packaging.