New modular inert gas systems

Paul Boughton

LNG and LPG carrier tanks hold both a source of income and a potential source of danger. To avert the danger, inert gas systems (IGS) have been required on all new tankers over 20,000dwt since 1978 — a move that has surely saved untold lives. Yet with increasing demand, tighter delivery schedules, the constant need to optimise onboard footprints and numerous other factors, Alfa Laval believes IGS should go beyond fire safety to protect against other disasters that chisel away at the potential income for both shipyards and ship owners.

As demand for LNG increases, a significant upturn is expected in new build contracts for LNG carriers over 40,000 cubic metres during the next five years. To remain competitive, it is increasingly important for shipyards to streamline both budget and timing while still delivering high-quality vessels that offer ship owners safe, reliable and profitable operation. In anticipation of this, Alfa Laval is now releasing the next generation of the Smit inert gas system for LNG and LPG carriers.

LNG and LPG carriers require very dry inert gas, making the inert gas systems installed on these tankers the most complex. Alfa Laval has spent decades optimizing cargo safety under the Smit Gas name, delivering the first IGS for an LNG tanker in 1971. Today Alfa Laval is the leading supplier for the low-pressure, low-dew-point inert gas generators typically used on LNG and LPG carriers. By taking a holistic view of IGS form and function, Alfa Laval aims to make a deeper difference for the bottom line with the new Alfa Laval Smit LNG/LPG.

Alfa Laval Smit LNG/LPG inert gas systems are constructed with a new, modular design comprising four main components: generator, cooler, chiller and dryer unit. This modular design allows tailored deliveries to shipyards to meet individual building demands.

“With our modular system we have a configurable system, using only the components needed for each particular build,” explains erben Heesen, Manager Marketing and Sales Inert Gas Systems for Alfa Laval.

“In other words, you pay only for what you need. Plus, it makes delivery times quicker and installation easier. For example, the dryer can be delivered in two main components (barrels) for easy transport. Both main components are easy to set up in a complete system together.

“Saving space is also an obvious benefit of the modularity,” says Heesen. “On board, every centimetre makes a difference, and the new modular Smit LNG/LPG system offers a considerably smaller footprint.”

By using water as an intermittent heat transfer medium between chiller and cooler, a stable heat transfer is created under all load conditions. The dryer unit is redundant and provides additional security. The cooler, which has gas contact surfaces of SUS 316 for lifetime service, takes up minimal space due to the low-temperature output of the generator.

Smit LNG/LPG also takes advantage of Alfa Laval’s new 2Touch controller, which makes any aspect of the system available in just two touches of the screen. As well as offering a graphical overview of the system, it provides quick access to functions and data. Using the comprehensive data at its disposal, Alfa Laval Touch Control ensures thorough system optimization. Naturally, it integrates seamlessly with other Alfa Laval automation systems and connects easily to ship control and communication.

All components for Smit LNG/LPG are engineered by Alfa Laval and manufactured at an Alfa Laval production facility that meets strict QA/QC standards, thereby safeguarding high product quality.

At the heart of the system is Alfa Laval’s unique Ultramizing combustion system, assuring low-oxygen-level inert gas without any soot formation. Oil is atomised in an ultra-fine dispersion pattern with steam assist, resulting in reduced NOx output. The system utilises a highly efficient, two-stage oil/air mixing technique which yields inert gas with 1% oxygen content possible and zero soot formation.

Besides safe combustion, the Ultramizing burner design meets Alfa Laval’s strict requirement for low emissions, as well as excellent operation during its entire life cycle. Horizontal installation also allows for easy maintenance, although maintenance is seldom required.

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