“The market is clearly moving towards LNG, not only for propulsion but also for supplying heat to the heat consumers in the engine room and cargo tanks,” says Pieter Borg, Manager Outside Sales, Thermal Fluid Systems. “Dual-fuel burners are already common in steam production, and this order is just the beginning for thermal fluid. Alfa Laval is currently in negotiation for several dual-fuel projects.”

Modifying for LNG

Thermal fluid heating systems are a frequent choice for smaller vessels, due to their reasonable installation cost and low maintenance. They were also the natural choice for the Groupe Desagnes asphalt carriers, since heating asphalt to a transport temperature of 200°C would require a steam pressure of 20-30 bar. Thermal fluid has 3-6 bar of pump pressure to overcome pressure losses in the line, which means less installation cost and risk.

Even so, modifications were needed to suit the dual-fuel design of the Groupe Desagnes vessels. “LNG has a major impact on the engine room, where double-wall piping, ventilation equipment and other precautions are required,” says Borg. “Apart from adapting the burners of the thermal fluid systems, we’ve had to make other modifications, for example in the automatic controls.”

A wide scope of supply

The Groupe Desagnes vessels will serve the Great Lakes and Canada’s St. Lawrence River, where temperatures can be as low as -30°C. A secondary hot water loop, filled with water and glycol, will therefore be connected to the thermal fluid heating systems in order to heat the engine room air intake and ballast water.

Alfa Laval’s full scope of supply for the vessels will include not only the thermal fluid heating systems, but also steam boilers, separators, boosters, filters, tank cleaning machines and ballast water treatment systems. Deliveries for the first vessel are to be completed by the end of 2015.