has completed an order worth around £1 million for the manufacture of
three Volatile Organic Compound (VOC) recovery process module
components. The systems were ordered in response to recent legislation
from the Norwegian Pollution Control Agency. Shuttle tankers to be
equipped with the systems will include the m/t Borga, m/t Knock An and
m/t Juanita, all operated by Navion, with further systems expected to be
ordered soon.
Navion was appointed VOC operator, for a partnership
by 23 oil companies, including Statoil, Shell, Esso and Norsk Hydro on
25th June 2002.
Allards is partnering Kvaerner Process Systems (KPS)
in Norway, which placed the order for the manufacture of absorption
columns and the knockout drums that comprise the main components of the
VOC modules. The VOC recovery systems are based on technology developed
by Kværner over several years. The environmental benefits of the
recovery system technology were first tested on a pilot plant in 1997
with the first full-scale plant successfully installed a year later. It
is claimed to be the only technology that satisfies Norwegian
regulations governing the loading of oil onto shuttle tankers.
The contract was part of an exclusive agreement with
KPS, which also subcontracted Allards for recent work for the Ekofisk
and Grane projects.
VOC process
The absorption columns manufactured for the Kværner
VOC contract measure 12 meters high by 3.5 meters in diameter.
Manufactured from carbon steel, the columns are built to work at 15 bar.
The knockout drums are 6 meters high and 2.5 meters in diameter and will
be operated at 3.5 bar. The VOC recovery process is based on the direct
absorption of volatile organic compounds in a side stream of the loading
oil. The oil containing the absorbed VOC is then re-mixed with the main
oil-loading stream. Absorption takes place in the absorption columns in
a counter current manner.
A typical system consists of an absorption column, a
crude oil pump, a gas compressor and an instrumentation and control
system. The equipment is assembled on a standard modular turnkey skid
which is supplied ready for hook-up to the ship's system. A side stream
of the loading oil, typically 5 to 10% of the total loading rate, is
routed through the VOC recovery unit. The side stream is pressurised to
between 5 and 15 bar before the oil enters the absorber column where it
is mixed with gas being displaced from the storage tanks.
Prior to entering the column, the emitted gas from
the storage tanks is compressed. A bypass line is installed for safety
in the event that the gas flow exceeds the compressor capacity. In the
absorber column VOC is preferentially absorbed into the crude oil under
pressure. The oil is then returned to the crude oil loading line and the
remaining gas is sent to the riser, or alternatively used to power
turbines on the ship.
The shuttle tankers are already in operation so each
VOC unit will be assembled as a single module weighing 220 tons and
measuring 23x10x4 meters. These modules will be retrofitted to the
ships, as they become available. The absorption columns and knockout
drums were delivered over three-week intervals to Karmoy Staal and to
the Kværner Rosenberg Yard in Stavanger.
Additional Company Information
Allards Verkstäder employs 50 people and specialises
in the design and manufacture of process equipment that includes shell
and tube, welded plate and rolled tube heat exchangers, petroleum tanks,
self-cleaning strainers and various other tanks and pressure vessels.
The company is a supplier of pressure vessels to Norsk Hydro and Kværner
and has just begun the manufacture of three heat exchangers for the
Knock Taggart FPSO offshore Nigeria. The heat exchangers for the
offshore industry are designed at the Allards International office in
Dundee, Scotland.
A copy of an article in Offshore Magazine
published by Pennwell based upon this press release can be found at the
following web address.
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