Hukka-5
The Alfa Laval Hukka-5 is a marine exhaust gas steam boiler designed to enhance waste heat recovery on cruise vessels and passenger ferries. Its revolutionary inverted, downward natural circulation design enables efficient recovery of engine exhaust gas waste heat while minimizing equipment footprint. This system harnesses physical phenomena to drive water through the boiler unit, eliminating the need for circulation pumps and further improving efficiency through reverse natural circulation.
Exhaust gas steam boiler with inverted natural circulation
- Optimized EGB footprint and minimized pressure loss, with a dual gas path exhaust design
- Standard, optional integration of electrical steam generation for port stays
- Innovative online cleaning for high-fouling flue gas applications using integrated Alfa Laval Aalborg OMA soot blowers to maximize real-life output
- Modular design with customizable multi-stage heat recovery and optional condensing cold-end for enhanced energy efficiency
- Simple, reliable operation based on natural circulation: no pumps or rotating components needed
The innovative design of Hukka-5 enables counter-current flow conditions, even within the limited space of ship funnels, resulting in a minimized exhaust gas boiler (EGB) footprint. It virtually eliminates the risk of flow instabilities in the evaporative circuits, despite exhaust gas temperature fluctuations that may occur when using new and alternative fuels.
The design delivers considerable savings, optimal operational performance, and enhanced safety in waste heat recovery systems on vessels with four-stroke engines that frequently dock in harbours, such as cruise vessels and passenger ferries. It eliminates typical problems associated with forced circulation systems - like cavitation, water hammering, and operational or maintenance losses. Its modular design allows for tailored configurations, including selectable multi-stage heat recovery solutions with an optional, extractable condensing cold-end, further improving your installation’s energy efficiency.
How Hukka-5 works
The design
The Hukka- 5 incorporates the same principal heat transfer features of a traditional exhaust gas economizer with forced circulation, but its unique design eliminates safety risks, heat losses, continuous maintenance needs and pump operating costs.
The heating surface of Hukka-5 consists of finned water tubes as standard, with a construction that minimizes soot build-up. Additionally, the system can be equipped with optimized steam rake sootblowers. Design pressure and boiler capacity can be tailored to specific requirements.
Hukka-5 is equipped with a vertical steam drum as a standard, allowing for optimal layout design and freedom from ship orientation installation constraints. There are no operational connections to fired boilers, which increases redundancy while reducing piping. The boiler’s dedicated water space circulation system eliminates the risk of water hammering and enables smooth integration of electric heating elements without involvement from fired auxiliary boiler unit(s).
Inverted, downward natural circulation enables counter-current flow conditions, minimizing the exhaust gas boiler (EGB) footprint and eliminating the risk of flow instabilities in the evaporative circuits.
The modular design allows for tailored configurations, including selectable multi stage heat recovery solutions with an optional condensing cold-end design, further enhancing installation energy efficiency.
Potential integration of electrical steam generation without additional pressure vessels, ideal for port stays where shore power is available for onboard electric heat generation.
Natural circulation
Natural circulation enables fluid movement within a system using gravity and density differences, eliminating the need for pumps. In the Hukka-5, circulation starts automatically when the engine runs and stops when the engine shuts down. Water remains inside the heating surface tubes during standstill, minimizing energy loss and virtually eliminating the risk of soot fires, similar to the preceding Alfa Laval Aalborg XWi design.
Because water only circulates through the Hukka-5 when the engine is running, there is no heat loss to cold air passing through the boiler during engine downtime. This reduces reliance on the fired boiler, resulting in lower fuel consumption and emissions.
When circulation stops, the boiler tubes remain filled with water, further reducing the risk of soot fires - a common issue with forced circulation systems. In forced circulation, sudden engine load changes can disrupt water flow, leading to pump cavitation and an increased risk of soot fires.
Service
We provide full support for our cruise & ferry steam boiler systems. Our support covers their entire life cycle, from design, installation and commissioning, past warranty and throughout the entire service life.
We can’t predict the future, but Alfa Laval Service Agreements can make it less uncertain. A fixed-period service agreement makes operation planning and cost projections more secure. A well-crafted maintenance strategy offers transparent cost control and safeguards performance, lengthening your equipment’s lifespan and reducing your total operating costs. Expert maintenance not only improves the performance of your Alfa Laval equipment, but also helps you get more from the equipment surrounding it.