Boiler Conversion – Coal to Wood Pellets
Fuel Handling System for a Major Dairy Processing Site
A major dairy processing site in New Zealand was converting two existing coal-fired steam boilers to wood-pellet firing as part of a large-scale decarbonisation project.
The project engineering contractor, Windsor Energy, engaged Conveyor Industries (CIL) to complete the engineering, design, fabrication, and installation of key fuel and ash handling equipment for the boiler conversion.
The project involved integrating new material handling equipment into an existing plant, with limited space and a tight installation schedule aligned with the site’s winter shutdown.
CIL's Scope
65 m³ Fuel Reception Hopper & Screw Feeder
Designed to receive and transfer both wood pellets and coal, providing controlled fuel flow into the boiler fuel handling system.
Boiler Feed Screws
Designed to move wood pellets to the boilers with control and precision.
Ash Screws
Designed to remove and transfer boiler ash as part of the combustion process.
Filter Dust Screws
Designed to handle collected dust from the filtration system and integrate with the site’s overall material handling process.
Designing for a Different Fuel
Switching from coal to wood pellets brings a different set of material-handling considerations. The equipment and system design had to account for the physical and flow characteristics of wood pellets, as well as the requirements associated with combustible dust.
Wood pellets:
- Have a lower bulk density than coal.
- Can degrade during handling and generate fines.
- Are sensitive to moisture.
- Can bridge or rat-hole depending on hopper geometry.
- Have different flow characteristics.
- Require careful consideration of conveying velocities and transfer points.
- Can create combustible dust hazards.
The team considered these characteristics throughout the equipment design to support controlled material flow through the system.
Integrating New Equipment into an Existing Plant
The project required incorporating new equipment around and into existing plant and confined spaces. This required careful consideration of available space, equipment interfaces, and installation requirements.
The installation also needed to be completed within a limited winter shutdown period. Engineering, fabrication, and installation activities therefore had to be closely coordinated to meet the installation schedule.
CIL’s involvement extended from engineering and design through to fabrication and on-site installation, providing continuity throughout delivery.
Outcome
CIL delivered the fuel reception, boiler feed, ash, and filter dust conveying equipment required to support the conversion from coal to wood pellets.
The completed installation integrates new biomass fuel handling equipment with the existing boiler plant, providing the material handling infrastructure required for the site’s transition to wood-pellet fuel.
The project demonstrates CIL’s capability to deliver bulk material handling equipment for complex brownfield projects, where new systems need to integrate with existing infrastructure while working within space and time constraints.
Supporting the Transition to Biomass Fuel
Conveyor Industries (CIL) designs, manufactures, and installs bulk material handling systems for industrial applications, from individual equipment packages through to integrated turnkey systems.
Related Equipment
Hoppers and Surge Bins
Screw Conveyors
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