The two new shuttle tankers for the KNOT Group will feature MHI-MME VOC-burning auxiliary boilers and a steam turbo genset. (Image: KNOT)
Two new dual-fuel 124,000 dwt shuttle tankers being built at the Daewoo Shipbuilding & Marine (DSME) yard in South Korea will feature a package of VOC-burning auxiliary boilers and generator turbines supplied by Mitsubishi Heavy Industries Marine Machinery & Equipment (MHI-MME).
The vessels will be installed in two 124,000dwt LNG-fuelled shuttle tankers under construction for Knutsen NYK Offshore Tankers. The shuttle tankers will be fitted with a Volatile Organic Compounds (VOC) recovery system.
By using the VOCs captured by the recovery system, these vessels will be able to lower their emissions of greenhouse gas emissions compared with conventional shuttle tankers, and improve fuel efficiency. However, MHI-MME notes that the VOC liquefaction and separation process captures heavier hydrocarbon fractions of the gas, but also produces a lighter hydrocarbon fraction, which is non-condensable.
While the vessels’ VOC Recovery system can process liquefied VOCs, the VOC firing auxiliary boiler can use both types. Especially from an environmental viewpoint, the benefit of VOC-firing boiler is to detoxify lighter VOC fractions which contain concentrations of 80% or more of inert gases such as nitrogen and carbon dioxide, and are difficult to process without the boiler.
In addition, the generator turbine is also effectively used in the ship as electricity provider and also contributes to reducing environmental impact by improving energy efficiency and reducing carbon dioxide emissions.
MHI-MME is only supplier that can supply both marine turbines and boilers with original design.
The deliveries of equipment to the yard will commence in the middle of 2021. When delivered, the shuttle tankers will operate in the oil fields in the Barents Sea and North Sea.