Mechanical Conveying in Power and Fuel Handling

Fuel handling moves coal, biomass or a blend from a stockyard or a silo to a mill, and ash handling moves the residue away. Both duties are long, outdoors, abrasive and almost always mechanical.

The hazard that makes this industry different is self heating. Coal and biomass oxidise, and a layer of fuel dust left on a conveyor frame, in a chute or in the bottom of an enclosure will warm itself. Add a hot bearing, a misaligned belt rubbing on a frame or a slipping drive, and the ignition source is in the same place as the fuel.

Abrasion then removes the equipment. Fly ash, bottom ash and mineral matter in coal wear chutes, liners, idlers and chain conveyors, and the wear concentrates at loading and transfer points where the impact energy is highest.

And the fuel changes. A plant commissioned on coal now takes wood pellets, husk or a blend, with different flow, different dust and different self heating behaviour running through equipment specified for something else.

Mechanical conveying in a power plant carries a fuel that changes between deliveries, so the equipment is specified against an envelope rather than against a material.

Equipment with condition monitoring that matches how rarely it is visited: bearing temperature, belt alignment, drive speed and, where the fuel justifies it, carbon monoxide or thermal detection along the route.

Housekeeping designed in rather than relied on: chutes and frames that shed dust, access to clean them, and no horizontal surfaces that collect a layer nobody can reach.

A specification valid for the fuel envelope the plant can receive, with a fuel change treated as a change to the equipment case.

In a battery material plant the hardened flight that survives abrasion contributes the iron the specification limits in parts per million.

Monitoring is the first design decision, because the equipment is unattended. Bearing temperature on every head and tail pulley, belt misalignment switches, speed monitoring on drives, and thermal or gas detection on enclosed sections where self heating is credible. The point is to find a warm bearing before it becomes an ignition source.

Chutes, transfer points and enclosures are then designed to shed rather than collect. A sloped surface, no ledge, no flat frame member under a transfer point, and access to clean what still accumulates. In fuel handling the housekeeping burden is set at design, and a plant that cannot clean a surface will not clean it.

Wear is placed in replaceable liners at the impact points, with a measured interval and the liners stocked, and the belt specification covers the top lump size and the impact energy at loading.

The fuel envelope is then written down. Flow behaviour, abrasiveness, dust generation and self heating differ between coal, pellets, husk and blends, and a documented envelope makes a fuel change a review rather than a surprise.

• Bearing temperature, belt alignment and drive speed monitored on unattended equipment.
• Thermal or gas detection on enclosed sections where self heating is credible.
• Chutes, frames and enclosures designed to shed dust, with access to clean the rest.
• Wear concentrated in replaceable liners at loading and transfer points.
• Belt and structure specified for top lump size and loading impact energy.
• Fuel envelope documented so a fuel change triggers an equipment review.

• Fuel envelope, including biomass and blends, rather than the commissioning fuel.
• Self heating behaviour, which sets the detection and housekeeping requirements.
• Abrasiveness and top lump size, which set liners, belt specification and impact protection.
• Outdoor service conditions, including winter temperature, rain and wind blown dust.
• Inspection frequency, which decides how much condition monitoring is justified.
• Access for cleaning, which determines whether housekeeping is possible at all.