Self-Unloading Vessels getting the lowdown

“The Great Lakes is a shared community. Many of the men and women on our ships not only work on our ships, they live in the Great Lakes region,” Barker says. “This important effort benefits the environment that we all live, work and play in, and has a positive impact on the health of the Great Lakes for the long term.”

The scrubber units, which are attached to the exhaust system of each of the ship’s two engines, effectively strip the majority of sulphur from its stack emissions. Here’s how the systems work: exhaust gas from the engine is sent through a series of absorption sprays that ‘wash’ and remove impurities, specifically sulphur and particulate matter. That washed gas then travels through a droplet separator before a clean plume of white steam is discharged into the atmosphere.

“The sulphur reductions have exceeded our expectations,” Barker says, adding that the additional reductions make an even stronger case for marine transportation — the most environmentally friendly way to deliver raw materials. “DuPont/BELCO has been an incredible partner in working with us on this effort of implementing freshwater closed-loop scrubbers on a retrofit basis. We are pleased with the performance of not only the scrubber units but DuPont/BELCO’s level of service, expertise and dedication to these important projects. We look forward to working with them further as we continue to supply our fleet with these scrubber systems.”

At the end of the 2015 navigation season, the Tregurtha and Barker will sail to Bay Shipbuilding in Sturgeon Bay,Wis., to have the scrubbers and associated equipment installed during winter layup, in early 2016. Bay Shipbuilding is where the first successful installation on the Oberstar was completed earlier this year.

As the operator of first US-flag fleet to implement the scrubber technology, the company was not only tasked with proving its emission-reduction capability but also taking the lead in developing a sustainable supply-and-delivery infrastructure to support its widespread use on the Great Lakes.

Specifically, the scrubber system relies on an injection of sodium hydroxide — to neutralize and remove sulphur from the exhaust gas – and that chemical has to be delivered to the vessel about twice a month.

Working with partners, Hawkins Inc., PVS Chemicals Inc., Garrow Oil & Propane and OSI Environmental, the company has established waterfront supply capability at Sturgeon Bay,Wis., and Detroit, Mich., and expects to develop a similar capability in Duluth, Minn., hopefully within the next month. From there, the supply-and-delivery infrastructure will be built out at ports located near East Chicago, Ill., and Burns Harbor, Ind.

The scrubber expansion announcement comes only weeks after the Company announced its plans to repower its last steamship — the Herbert C. Jackson — in the final phase of a ten-year, $100 million modernization effort.

On August 11, 2015, CSL’s Trillium-class self-unloading Laker Baie St. Paul began discharging the first of 269,000 metric tonnes of aggregates in the opening phase of the construction of Montreal’s new Champlain Bridge. Less than 30 days later, the discharge operation was complete.

The complex, ten-trip operation necessary for the construction of a laydown in the St. Lawrence River proved a technical challenge that made the most of standard Trillium-class features including dynamic positioning (DP) features and remote- controlled self-unloading systems. The laydown area would eventually serve to position the equipment necessary to build the new Bridge and provide the base for the soaring twin pillars that are central the bridge’s design.

Baie St. Paul was required to discharge the aggregates while moored to three temporary barges in a restricted stretch of the St. Lawrence Seaway. Situated on a bend, the discharge location left Baie St. Paul occupying almost half of the busy shipping channel and resulted in regular ship-to-ship interaction including some slight movement of the CSL ship. With traffic passing at seven to eight knots within meters of the ship, the operation relied heavily on the vessel’s state-of-the-art capabilities.

Baie St. Paul’s dynamic positioning features integrates the main propulsion system, steering nozzle, and bow and stern thrusters, all of which can be controlled independently or together using a joystick. Rated at 1,000kW at 1,190rpm and 800kW at 1,185rpm respectively, and powered by electric motors equipped with variable frequency drives (VFD), Baie St. Paul’s bow and stern thrusters were kept online along with the 8,750kW main engine as other ships passed, ready for use in the event of excessive movement. The thrusters also had the critical role of keeping the vessel in position next to the barges during mooring and when the lines were being removed prior to departure.

“High manoeuvrability is a huge advantage, especially in restricted waters. The advanced position-keeping technology makes Baie St. Paul the safest option for this kind of operation,” noted Allister Paterson, president of Canada Steamship Lines.

Operational safety was also enhanced by other standard Trillium Class features such as an ergonomic bridge equipped with NAV1 notation and IBS notation-compliant monitoring and alarm systems.

The technology that’s built into Trillium-class ships to control the unloading rate — like the VFD-equipped belts and feeder gates — gives them the flexibility and capability to meet any requirement. While capable of unloading 5,000tph (metric tonnes per hour), the ability to customize the discharge rate as requested by the shore foreman kept the cargo flow to a manageable level for the excavators, bulldozers and trucks.

Advanced Trillium-class environmental features also proved invaluable to the operation, including the enclosed, noise- reducing discharge boom and oil-free propulsion train. Both helped ensure that CSL’s operation had minimal risk of impact on the surrounding communities and marine ecosystem.

EMS-Tech Inc. – self-unloader update