Liquefied Natural Gas (LNG) has a lot going for it; not only is it clean, competitively priced, and abundant, but it is flexible. LNG-related developments are happening at a pace as companies in this new and fast-growing sector seek to become more efficient and competitive. Developments in offshore gas hubs, major ports are testament to a trend for upgrading infrastructure and processes for ship-to-ship LNG transfer. For example, offshore floating liquefied natural gas (FLNG) and LNG bunkering services are becoming increasingly common, relflecting the need for safe, effective and high value ship-to-ship transfer solutions.
Whether gas will eventually end up being combusted for power generation, as a marine fuel or other uses, it presents a new set of challenges for those required to transport and transfer it. Unlike coal and fuel oil, gas cannot be transported within the confines of a traditional bulk carrier or tanker. Gas is liquefied for ease of transport and transfer purposes. Not only does this require new vessels, in the shape of LNG carriers, but it also requires fresh thinking in the ‘transfer zone’; where ship-to-ship loading and unloading occurs.
Traditional thinking has been that an LNG vessel would moor alongside a FLNG vessel or unit, such as a Floating Storage Regasification Unit (FSRU), using loading arms for ship-to-ship transfer. However, this transfer method was based upon transferring traditional cargoes such as fuel oil and coal. Gas, and its liquefied form, presents a different challenge, in as much as it needs to be transported at a temperature of -163 degrees Celsius.
So, while a traditional bridging arms and jetties could still be used, it would require specialized hosing to transfer LNG to offshore units. In many cases, there will certainly be a requirement for traditional methods (and these can be utilized in tandem with hoses). However, because of the requirement for specialist hoses for LNG transfer, far more focus than before has been given to the hose technology and the flexibility of the range of solutions it can provide – both onshore and offshore.
Trelleborg’s research and development facility for hoses in Clermont-Ferrand, France, has developed game-changing Cryoline technology that enables quick installation and can significantly reduce capital expenditure – while not compromising on high levels of safety. Utilizing the latest technology, each cryogenic floating hose is equipped with an integrated monitoring system that is able to detect even the slightest leak that may occur in the hose structure. The system uses cutting-edge optical fibre technology that offers a fast, effective, and reliable control system, to monitor conditions during loading and offloading.
During the development of the Cryoline hose-in-hose technology, several full-scale hose prototypes were successfully tested in both static and dynamic conditions – with most tests taking place in cryogenic conditions at -196 °C/ -321 °F - demonstrating their ability to withstand fatigue resistance in even the most hazardous conditions. Trelleborg’s cryogenic floating hoses are operable in all sea states, and are available with large inner diameters ranging from 6-inches to 20-inches. It is possible to achieve a flow rate of up to 12,000 m3/h, using two lines.
Cryoline also addresses the issue of boil-off gas generation which can cause valuable energy loss during the transfer process. Cryoline insulated hoses reduce boil-off by as much as 60% – equating to a saving of 10 billion btu’s of energy saved over the course of 500 transfers.
Significantly, Trelleborg’s cryogenic hose-in-hose technology can negate the need for fixed onshore infrastructures; a concrete platform onshore combined with Cryoline hose transfer solutions offers an alternative that can be up to 80% more cost effective for locations where fixed onshore infrastructure would be prohibitive.
Offshore Ship-to-Ship Transfer
Cryoline technology has the potential to deliver significant benefits for offshore transfer, where floating receiving and distribution terminals and coastal gas carriers are now an integral part of LNG activities and a crucial cog in the LNG supply chain, and LNG bunkering expands to cater to a growing segment. While they offer more flexibility for storage and transfer outside of increasingly congested ports, whilst minimizing voyage time, the highest levels of safety must still be maintained amid the effects of winds, waves, and currents in the open seas.
In addition to the high flow rate, which reduces risk, by shortening the length of time the vessels must be connected, tandem loading and offloading allows vessels to increase the separation distance – further mitigating the risk of collision and ensuring the safety of the vessels and crew.
Trelleborg’s Cryoline handling solutions were specifically developed for two important growth areas in LNG offshore handling: ship-to-ship floating configuration and ship-to-ship aerial configuration. The heavy-duty hose design reduces risk of damage to the hose during handling. The technology offers a viable and innovative alternative to existing ship-to-ship transfer systems, while ensuring high safety and operability standards are upheld.
In deeper water or more hazardous conditions, Trelleborg’s floating cryogenic hoses permit transfer to occur between vessels moored as much as 300 to 500 meters away from a storage unit, allowing for ship-to-ship transfer in deeper waters in even the most challenging conditions, where the proximity of side-by-side transfer at a lesser distance could pose risks.
In less harsh environments, where aerial transfer is a feasible option, Cryoline offers operators a greater choice of configuration, more flexibility, and in some cases reduced operational expenditure. For example, in ship-to-ship aerial transfer, lifting and handling procedure time can be reduced by as much as 60%, by using only three of Trelleborg’s 16-inch Cryoline hoses or four 12-inch hoses, instead of the typical twelve eight-inch hoses. As well as saving time, this decreases risk, by shortening the length of the transfer window. With no use of “Y-piece” joints required, Cryoline technology ensures less handling, fewer potential leak points, and less likelihood of pressure outage, while loading and offloading lead time is greatly reduced.
Cryoline technology is also ideally suited to offshore LNG bunkering, thanks to the safety, durability and flexibility of the technology. LNG provides a viable solution for ship owners and operators to help them meet existing and forthcoming global environmental regulations – most notably the 2020 sulfur cap implemented by the IMO’s Marine Environment Protection Committee (MEPC) in October last year. In addition, since 2005, all ships trading within sulfur Emission Control Areas (SECAs or ECAs) are required to stop using heavy fuel oil and instead choose fuels with a less than 0.5% sulfur content. As the global LNG-powered fleet expands, so too does the demand for LNG bunkering.
Trelleborg’s Cryoline hose-in-hose solution is an example of a technology that is making the acceptance of LNG as a marine fuel easier, by ensuring efficiency, reliability, and above all, safety in the bunkering process. By opening up the potential of conducting LNG bunkering operations offshore, this technology lessens the need for ships to come into the harbor or port to fill their tanks, resulting in more efficient time management and less congestion.
A bright future for Cryoline
The end result reflects a quiet revolution in energy transfer. A report by Mordor Intelligence, published August 2016, entitled ‘Global Cryogenic Equipment Market - Growth, Trends and Forecasts (2016 - 2021)’, estimates that the global cryogenic equipment market was $15.3 billion in 2015 and projected to reach $23.5 billion by 2021, at a growth rate of 7.4% per annum during the forecast period.
Trelleborg’s own investment in research and development of Cryoline hoses – dating back seven years – illustrates just how significant this technology will be in enabling gas transfer and distribution over the coming decades. Cryoline LNG ‘hose-in-hose’ solutions combine existing and proven technologies (including composite hose and rubber bonded hoses), customized for LNG from longstanding technology that has been proven in oil transfer applications for the past 40 years.
Cryoline technology for LNG transfer enables an acceleration of productivity levels; leveraging technology specifically designed to manage the transfer of liquifed gas, often in extreme environments.
As a clean, competitively priced and abundant energy source, demand for LNG will only grow in new regions and locations. As these markets develop, so the necessity for multi-faceted loading and unloading transfers will too. To keep pace, managing the intensity of life in the ‘transfer zone’ needs new, flexible, and innovative thinking to support growth acceleration and minimize costs.