Tuesday, September 19, 2017

Cryogenic floating hoses open up frontiers in LNG transfer

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Vincent Lagarrigue, Director, Trelleborg Oil and Marine explains how a rapidly diversifying LNG market requires transfer solutions to evolve to keep pace

While global demand for LNG (liquefied natural gas) shows little sign of slowing, demand patterns are changing, requiring increasing flexibility from those who transport and transfer this fuel. According to a recent study, global demand for LNG is projected to increase by a factor of 50% by 2020, compared to 2014. While traditional import hubs such as India and China are leading this charge, several new LNG importers including Poland, Jordan, Malta, and Pakistan have emerged in the last two years. In addition, remote, developing regions in Indonesia and the Philippines are looking to LNG to fill the energy gap where access to the main grid is limited or unreliable, or where power generation capabilities are restricted.

In delivering LNG to these more remote areas, the fuel needs to be split into smaller load parcels to reach regions that are not connected to an existing pipeline grid. This is driving diversification in the global LNG-carrying fleet, with a growing segment of smaller vessels emerging and a greater need for options in ship-to-shore transfer. Today, the live LNG fleet of around 500 vessels includes 26 FSRUs and 33 small-scale LNG ships of 30,000m³ or less – and the number in this smaller fleet is increasing.

Offshore elements remain vital. FLNG (Floating LNG) projects are picking up, and FSRU (Floating Storage and Regasification Units) continue to be essential links in the LNG supply chain. As the LNG network expands, ship-to-ship loading and offloading continues to push into remote locations, deeper waters and harsher conditions.

These trends are accompanied by the rise of LNG’s use as a marine fuel. Over 100 vessels are now running on LNG – and demand will only grow in line with regulations such as the 2020 global sulphur cap and the expansions of emissions control areas (ECA). This again requires more flexible transport of LNG in smaller packages, and an expansion of ship-to-ship and ship-to-shore transfer options to ensure safe LNG bunkering that will not impact already congested ports.

The combination of these factors means we need to rethink LNG transfer. Traditional thinking has been that LNG vessels would moor at the dockside and use a jetty platform for ship-to-shore transfers, or use bridging arms for ship-to-ship transfers. While effective in certain situations, the trends outlined above mean that LNG transfer must take place in environments where this type of infrastructure would be prohibitively expensive, either due to harsh conditions, or because waters are too deep or shallow to allow a jetty to be constructed. In addition, many existing terminals set up for larger carriers, may not be equipped to handle transfer to and from smaller vessels.

This is where the latest LNG hose technology holds the key to unlocking a wider range of transfer possibilities. Because LNG needs to be transported at a temperature of -163 degrees Celsius, LNG transfer solutions require specialised cryogenic hosing to safely transfer LNG to regasification plants, and as such, considerable research has gone into the development of cryogenic hoses. Cryogenic floating hoses in particular enable a range of new transfer options.

Composite LNG hoses typically consist of multiple, unbonded, polymeric film and woven fabric layers encapsulated between two stainless steel wire helices – one internal and one external. Essentially, the film layers provide a fluid-tight barrier to the conveyed product, with the mechanical strength of the hose coming from woven fabric layers. The number and arrangement of multiple polymeric film and woven fabric layers is specific to the hose size and application. The polymeric film and fabric materials are selected to be compatible with the conveyed product and the operating temperatures likely to be encountered.

Additionally, insulated hoses - such as Trelleborg’s Cryoline range - can reduce boil-off by as much as 60%, equating to a saving of 10 billion btu’s of energy over the course of 500 transfers. The outer protective hose draws on flexible rubber-bonded hose technology, which is well-known for its high resistance to fatigue and its ability to withstand harsh environmental conditions.

The flexibility and high flow rates achievable by cryogenic hose technology increase the economic feasibility of power generation, terminal, and marine bunkering projects which are located away from existing infrastructure – particularly in areas where jetty-based transfer would be unfeasible because of harsh conditions or environmental concerns. A major advantage of hose-in-hose technology is that it can negate the need for large scale fixed onshore infrastructures; a concrete platform onshore combined with Cryoline hose transfer solutions offers an alternative in locations where fixed onshore infrastructure costs would be prohibitive.

The options further expand when combined with a floating platform. This increases the operability of the terminal, as the hose and platform can be retracted when not needed, or when harsh weather conditions would present hazards. They can function either as standalone units, or enhance a larger terminal’s ability to handle deliveries from smaller vessels.

Similarly, in offshore environments, cryogenic hose technology allows transfer to occur in deeper seas and in more challenging conditions. Cryogenic floating hoses can be used in a tandem configuration, significantly increasing the distance between the vessels involved – by approximately 100 – 150 metres for FLNG to carrier transfers, and 300-500 metres for carrier to FSRU offloading transfers. These extended distances play an important role in mitigating the risk of collision – as does the fact that the high flow rates afforded by the hose technology significantly reduce the length of the transfer operation, further lowering risk.

As LNG evolves and its uses diversify it must shift from a niche power source to a ubiquitous part of the global energy mix. If LNG is to reach its full potential, it is vital that transfer technology keeps pace; cryogenic hose technology is demonstrating that transfer innovations can match the ubiquity and flexibility of the fuel itself.

A video about Trelleborg’s range of cryogenic hoses is available here

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