Working Principle of Charcoal Making Machine

A complete charcoal making line converts biomass waste (sawdust, straw, rice husk, tree branches, etc.) into machine-made charcoal.

Its core workflow consists of three major stages: Raw Material Pretreatment → Briquette Forming → Carbonization.

Loose biomass materials are processed into dense, high-calorific-value charcoal through this systematic process.

Large-sized biomass such as branches and wood blocks are crushed into uniform fine particles by a wood crusher.

The standard particle size is below 5–10 mm.

Crushing increases the specific surface area of materials for better drying and extrusion performance in the next process.

Raw biomass naturally carries high moisture content, ranging from 20% to 40%.

The qualified moisture requirement for briquette forming is 8%–12%.

A rotary drum dryer uses hot air to reduce moisture to the standard level.

Fully dried materials are fed into the screw briquette extruder.

Forming is realized by combined mechanical extrusion and frictional heating pyrolysis.

The key components are the screw propeller and forming sleeve (mould).

Green briquettes are loaded into a carbonization furnace to undergo oxygen-free pyrolysis and turn into charcoal.

The whole carbonization process is divided into four continuous phases under anoxic or micro-oxygen environment.

Residual moisture inside green rods evaporates completely.

Only physical water removal occurs with no chemical decomposition.

Hemicellulose decomposes first, releasing CO₂, CO, water vapor and other volatile gases.

Materials soften gradually with continuous weight loss.

Cellulose and lignin decompose massively, producing methane, tar and other volatiles.

The remaining solid substance is mainly elemental carbon, forming preliminary crude charcoal.

To upgrade fixed carbon content and calorific value, the furnace temperature can be raised to 500–800°C.

Residual volatile matters are fully driven off, resulting in more stable and higher-grade charcoal.

Oxygen level inside the furnace must be strictly controlled throughout carbonization.

Sufficient oxygen will cause complete combustion instead of carbonization.

Sealed furnace structure and adjustable air intake achieve stable anaerobic pyrolysis.

The complete production flow:

Biomass raw material → Crushing → Rotary Drying → Screw Briquette Extrusion → Oxygen-free Pyrolysis Carbonization → Final Machine-made Charcoal.

Advanced production lines collect combustible pyrolysis gas (CO, methane, etc.) generated during carbonization.

The recovered gas is reused as fuel for the dryer and carbonization furnace, realizing closed-loop energy recycling and energy conservation.