Wood Pellets

Pellet terminals move millions of tonnes with equipment that looks like grain handling, and the differences are the dangerous part.

Fines are made by the plant

Durability is measured in the laboratory, but the fines percentage at the boiler is set by how many times the pellet was dropped on the way.

• Cascade and spiral chutes instead of free fall into ships and silos.
• Conveyor transfer points designed to match belt speeds and limit impact.
• Screening before loading, so the dust is removed where it can be captured.

Dust explosion risk

Wood dust is combustible and the terminal has every ingredient in one place: fine dust, enclosed conveyors, elevators and ignition sources.

Explosion venting, isolation between vessels and a housekeeping regime that removes settled dust before it can be lofted are standard rather than optional.

Self-heating and off-gassing

Fresh pellets oxidise, and the reaction is exothermic in a large pile with poor ventilation.

Carbon monoxide builds in the headspace to concentrations that are lethal and odourless, which has caused fatalities during silo entry.

Temperature profiling, gas monitoring and controlled ventilation before entry are the controls that matter.

Water is the enemy

A wetted pellet swells and falls apart, and a block of swollen pellet mass inside a chute or silo is a mechanical problem as well as a quality one.

What to establish before buying equipment

• Durability index and the fines limit agreed with the offtaker.
• Drop heights across the whole chain from production to boiler.
• Silo ventilation, gas monitoring and entry procedure.
• Explosion characteristics of the dust fraction actually collected.