The LNG sector has experienced profound change over the past 12 months as it continues to come to terms with a changing landscape of increased demand and tougher environmental regulations. The market will continue to mature throughout 2019, with momentum growing for both small-scale LNG projects and LNG as a marine fuel, giving rise to the development of new infrastructure projects around the globe.
While the overall prognosis of the industry looks promising, the diversity of ongoing and future projects and the inherent risks of handling LNG will necessitate an increased focus on safety when it comes to the transfer zone. The transfer of natural gas is much more complex than that of heavy fuel oils due to the extremely low temperatures involved, and therefore requires highly specialised equipment. If we are to ensure the highest safety standards across the industry the first players will need to rapidly innovate to develop the right technology.
In this paper, Trelleborg Oil and Marine will discuss the results of a successful field operation of an integrated monitoring system for cryogenic hoses, along with its multiple applications in maintaining and improving safety standards in ship-to-ship and ship-to-shore LNG transfers.
Cryogenic hose-in-hose technology for loading and offloading in marine environment with floating, aerial, or submarine configuration, is a vital part of safe LNG transfer infrastructure. The dual-carcass design consists of an inner cryogenic hose – which safely transfers the LNG or cold vapour, with minimal pressure drop – and an outer hose designed to provide protection from the external environment as well as buoyancy in a floating application.
This is underpinned by an integrated monitoring system, based on cutting-edge optical fibre technology, which allows detection of even the slightest leak that may occur in ‘real-time’ in the hose structure. If a leak occurs, the cryogenic fluid or vapour enters the annular space between the inner and outer hose. This leads to a local temperature drop, rapidly detected and located by the Distributed Thermal Sensing (DTS) system. This then triggers an alarm on the user interface, which permits the operator to manage and control the LNG transfer operation.
The residual leak gas is guided to the end of the transfer line where it is re-routed or burned off – avoiding any loss to the atmosphere.
The integrated monitoring system can also be used during the precooling and hose purging operations, as proven during a successful field operation of Trelleborg’s cryogenic hoses in Herøya, Norway, as part of the world’s first jettyless ship-to-shore LNG transfer using a floating offloading system. The project, which was accomplished with the support of Naturgy, and in partnership with Connect LNG, successfully validated both of these functions in real-life conditions, allowing the operator to follow the precooling status in real time and ensure that no liquid was left in the line at the end of the operation.