PROJECT PROFILE

Our wood chip drying project in Romania has applied our new process drying equipment. The production line is highly valued by our company leaders in design, installation and commissioning. With more than ten years of project construction experience, the technical team pays more attention to the project quality. We have built a high-quality drying project for our customers. At present, the equipment has been officially put into production, which is believed to bring convenience to the local treatment of wood chips.

PROJECT PROCESS

Workflow of wood chip drying and rod making production line

I. Raw material pretreatment process

Crushing and screening: Large-sized wood chips (such as wood blocks, branches, etc.) need to be crushed twice by a hammer mill or a knife disc integrated machine to ensure that the material size is ≤3mm.

The impurities (such as stones and metal debris) are separated by a vibration screening machine, and qualified materials enter the drying system through a conveyor belt.

Moisture content detection: The initial moisture content of the wood chips after pretreatment needs to be tested. If it is >30%, the subsequent drying time needs to be extended or the drying intensity needs to be increased.

II. Drying process

Feeding and preheating: The wood chips are evenly fed into the drying drum by a spiral feeder. In the initial stage, the temperature is raised to 40-45℃ at a rate of 5℃/h, and steam spray is turned on to maintain a humidity of 85-90% (to prevent the surface from dehydrating and cracking too quickly). ‌

Main drying stage‌: The material is boiled and fluidized in the drum through the lifting plate and hot air system (temperature 50-80℃, wind speed 1.5-3.5m/s), and the water is continuously evaporated to the target moisture content (normally 12-15%). The temperature of hardwood (such as oak) needs to be controlled at ≤65℃, and the temperature of softwood (such as pine) can be raised to 80℃. The humidity is dynamically adjusted according to the tree species.

‌Discharging and monitoring‌: After drying, the material is transferred to the temporary storage warehouse via the conveyor belt, and each batch needs to be sampled for moisture content testing (error ≤0.5%).

III. Briquette making process

‌High-pressure extrusion molding‌: The dried wood chips enter the rod making machine through the screw conveyor, and are extruded into hexagonal hollow rods (normal outer diameter 50-60mm) through the mold at a high temperature of 220-280℃ and a pressure of 30-50MPa.

‌Cooling and shaping‌

The high-temperature bars are cooled to room temperature through an air-cooled conveyor belt to avoid a loose structure due to thermal stress.

IV. Carbonization treatment (optional)

‌Oxygen-free carbonization‌: The formed bars are sent to the carbonization furnace and carbonized for 4-8 hours in an oxygen-free environment at 400-600℃ to convert into high calorific value mechanism charcoal (fixed carbon content ≥75%). The carbonization tail gas is treated with tar and other by-products through a condensation recovery system.

V. Auxiliary system integration

‌Conveying system‌: Enclosed belt conveyors or screw conveyors are used throughout the process to reduce dust.

‌Dust removal system‌: Cyclone separators + bag dust collectors are configured in the crushing and drying sections, and the dust emission concentration is ≤20mg/m³.

‌Intelligent control‌: Temperature and humidity sensors and variable frequency speed control modules are integrated through PLC to achieve automatic parameter adjustment and fault alarm.