Project: RTI Phase 1: Storage Remediation
Client: Houston Pellet Limited Partnership
Location: Prince Rupert, British Columbia, Canada
In 2006, Houston Pellet constructed the first phase of a wood pellet transhipment facility on Ridley Island in Prince Rupert, BC. Three years later they realised that their high capacity steel storage silo was suffering from two ever-increasing problems; a loss of capacity and deterioration in product quality.
Houston Pellet called upon CMC to find a solution to their storage and quality problems. A review of the flow characteristics of the transport systems and the silo geometry revealed several problems but most particularly the silo feed arrangement and the silo floor geometry.
The repairs and modifications developed for the silo included:
- Removal of the trapped material in the silo.
- Installation of a high capacity bean ladder to reduce product breakage and dust during the filling process
- Construction of wedged floors and transverse pyramids to improve outflow and achieve self-cleaning of silo floor
- Replacement of discharge belt feeders with new laminar flow units to reduce breakage and dust production
- Installation of a new higher efficiency aeration system to reduce self-heating and the subsequent product deterioration
A repair and improvement program was developed with the goal of minimising the plant shut down period. While product was rerouted to an alternate facility to allow the Prince Rupert plant to be shut down, work crews were assembled and organised to operate around the clock until the remediation work was complete. The sequence included:
- Emptying of several hundred tonnes of lost material compacted in the bottom of the silo. The material was actually reloaded on to railcars and returned the Houston Pellet facility for reprocessing
- Construction of an 10.8 m high concrete retaining wall inside the silo
- Installation of 6200 tonnes of compacted fill to form the wedges and pyramids
- Finishing of the wedges and pyramids with a hand trowelled concrete coat
- Fabrication and installation the new internal equipment including the bean ladder and the aeration system
- Removal and replacement of the central hopper’s discharge hopper and belt feeder
- All associated electrical and control work
The entire process was accomplished in approximately six weeks.