A further milestone has been reached with the on-time delivery
of key components of the Integrated Waste Management System (IWMS)
for the new Queen Elizabeth Class aircraft carriers. This latest
delivery includes the Oily Water subsystem and remaining hardware
for the Solid Waste and Final Treatment subsystem, including the
two pyrolysis plants supplied this month.
The IWMS, designed by Babcock under contract to the Aircraft
Carrier Alliance, will be the first fully integrated waste
management system in a warship, and incorporates a range of
technologies and processes for the collection, transfer, treatment,
stowage and disembarkation of the various fluid and solid waste
streams generated onboard the carriers, ensuring they are either
benign and compatible with International Maritime Organisation
(IMO) requirements for overboard discharge, or enabling them to be
stored efficiently until landed. The system will minimise the
manpower requirement and remove some of the current labour
associated with waste handling, as well as freeing up valuable
on-board storage space, and minimising reliance on shore side
facilities. It also has sufficient reserve capacity to allow
continuity through maintenance periods to meet all operational
requirements.
The Oily Water System processes the ship's oily water to output
waste oil, which can be introduced into the pyrolysis unit, and
MARPOL-compliant permeate that can be removed from the ship.
The Solid Waste and Final Treatment subsystem, which comprises
approximately 100 items per ship, involves a number of different
pre-processing methods for the various waste streams (including dry
mixed refuse, food waste, sludge oil, waste fuel or oils and
grease, and bio-sludge from the membrane bioreactors), in
preparation for pyrolysis. This is conducted by a variety of
specialist, commercial off-the-shelf equipments, each chosen to
match the particular waste stream's characteristics, such as water
content and particle size.
Pyrolysis is the final stage, involving the heating of waste in
the absence of oxygen to release gas, which is then combusted. The
heat from the combustion process is passed back into the outer
jacket of the pyrolyser to heat the waste, making the process
self-sustaining. Meanwhile, the solid char is collected in a char
separator for automatic decanting into a storage drum. The system
builds on the first trial maritime installation of the new
pyrolysis technology, supplied by QinetiQ, on HMS Ocean in 2008.
The system produces char representing around 15% of the original
mass; a valuable 85% reduction in waste volume for easy and safe
storage until the vessel returns to port.
Babcock project manager James Woolford commented: "The Solid
Waste and Final Treatment subsystem is a fundamental component of
the IWMS system, and the successful delivery of this equipment,
well ahead of the required-in-yard dates, is an important milestone
in the programme. Delivery of the two pyrolysis units this month
follows the remaining system hardware which was delivered in
August. The only outstanding hardware for the Queen Elizabeth's
entire IWMS is now the third Waste Water Treatment Plant, currently
being assembled at Babcock's Bristol site and required-in-yard in
November this year."
All equipment delivered will remain at the Aircraft Carrier
Alliance's storage facility in Glasgow until called for by the
shipyards over the next 18 months.
Installation of the IWMS at the shipyards will be undertaken
with support from Babcock, who will also undertake commissioning of
the system and harbour and sea acceptance trials, for final
acceptance on the QE Class by the Aircraft Carrier Alliance.