Industry Insight: Fresh Thinking in Scrubber Design

Neil Anderson, Director of Marine Technologies, LAB SA, a subsidiary of CNIM Group. Image Credit: LAB SA

With the impending 0.5% marine fuel sulphur cap, there is increased interest in exhaust gas emissions cleaners, or "scrubbers", as one of the three principal routes to compliance.  Cargill, one of the largest charterers of dry bulk vessels in the world, recently indicated that it would move to open-loop scrubbers on larger dry bulk vessels that ply long-haul routes. And commodities trader, Trafigura has also announced its intention to install scrubbers on its fleet of newbuild tankers to comply with 2020 regulations. With around 400 vessels that currently have scrubbers installed or on order, plus weekly news of those planning to pursue this compliance option, it is increasingly clear that the business case for scrubbers on certain vessels is persuasive.

With the prime focus on the economics, and the potential financial advantage to be gained from continuing to burn less expensive heavy fuel oil (HFO) instead of the costlier, low sulphur fuel, discussion around the practicalities of design and installation has been understandably muted. However, for those considering scrubbers, it is important to understand the available options in terms of design and materials. The majority of scrubbers on the market are made from high-end alloys but there is fresh thinking in terms of what a scrubber should be made of, with an alternative lighter, composite scrubber also available.

The traditional high-end alloys have been proven across a wide range of industries, including marine, power, energy and waste. However, while alloys have the advantage of being readily available, the physical properties need to be considered in respect of maintenance and servicing. 

Exhaust gas scrubber units and the full system components face very corrosive products at high temperature, and higher-grade materials have more resistance to oxidation, corrosion and high temperature. It is important to carefully assess materials offered by makers – this includes the scrubber, pipes, tanks, valves, coating systems, containment systems and monitoring equipment.

Scrubber manufacturer LAB, part of CNIM Group, has a 60-year heritage in flue gas treatment. Based on industry insight gained across multiple applications, LAB has pushed the boundaries of flue gas treatment by developing a composite scrubber as an alternative to alloy which it also continues to use. In comparison to the traditional alloy version, a composite scrubber has a number of advantages.

The composite material is 20-30% lighter than a similar version made from high-end alloys, reducing load at sea and reducing fuel consumption.

In contrast to the corrosion that has been reported on some alloy scrubbers, the physical properties of the composite significantly removes the risk of corrosion and is equally as durable as traditional alloy. Extended material guarantees may also be available.

The configuration is available for offline application, providing greater flexibility as the scrubber can be configured to accommodate main engines, auxiliaries and boilers.   Any necessary repairs or maintenance to offline solutions can be made in situ, however inline systems may require removal for repair.

In an era of increasing environmental regulation, operating modes are also keenly debated, with some suggesting future requirements, particularly in the EU nations, to cut the effluent discharges associated with open loop scrubbers. However, scrubbers can be operated in open loop, hybrid, or closed loop mode - with certain open loop installations able to be adapted to closed loop, providing the opportunity to future proof vessels should regulations change. LAB's technology offers customised solutions for both offline multi-streaming and inline configurations, maximising customer choice according to the nature of the vessel.

LAB's DeepBlueLAB SOx™ scrubber is the only system in the market that can be manufactured in either composite or high-end alloys multi-streaming offline solution. The composite technology has been rigorously proven over the past three years with thousands of hours of operational service with Brittany Ferries.

Scrubbers do not represent a silver bullet solution for the whole of the merchant fleet. However, for many ship owners it is a viable and commercially compelling option. Factors for consideration include: the age and type/configuration of the ship, the capacity of the fuel tanks, its trading route / patterns, what types of fuels will likely be available at the different ports and a cost-benefit analysis; and the company's access to finance.

There is little doubt that the shipping industry faces a more expensive and challenging future. Composite scrubbers represent a fresh approach to scrubber design and herald a new era of options for the maritime industry. The composite material provides greater operational security by reducing the risk of corrosion and the subsequent cost and impact of repair and maintenance. By taking decisive action now, ship owners and operators can be sure they will be compliant in 2020 while reaping the rewards of the high and low oil price differential.