[IN DETAIL ENERGY]
Twentyfour7.
by three Brazilian IPPs - Geradora de Energia do
Amazonas SIA, Companhia Energetica Manauara, and
Rio Amazonas Energia SA (part of Multiner SIA) - to
convert their generating stations. All three companies
have power plants located in the City of Manaus and
indicated their desire to be able to use every possible
fuel alternative in the future.
While the reasons behind
this move include
environmental considerations, the need for redundant
generating capacity and the ability to take advantage
of the lowest-cost fuel options, the key driver has been
the expectation that natural gas will be available in the
region in 2010. The gas conversion projects will be
carried out at all three power plants concurrently.
Each of the three 85 MW power plants has five
Wartsila 18V46 engines. When they were delivered
in 2006, gas was not available. The plants were,
however, pre-designed to facilitate the conversion work
which allows them to be switched from their current
baseload operation using HFO to operating on gas.
Wartsila is currently operating and maintaining
all
three plants under contract, and will therefore ensure
that they continue delivering optimum performance
and levels of reliability after the conversion work has
been completed.
1
_ ...__ ·__ ._,__
ALL THREE
MANAUS
PLANTS WILL
UNDERGO GD
CONVERSIONS.
·ourl. 2.09
New gas feed systems
As the engines will continue to need pilot fuel in small
quantities, the conversion process involves adding a gas
feed consisting of two injectors. Having two separate
fuel-feed systems means that the engines can be run
on either gas or liquid fuel, with the choice depending
on how much gas is available.
One consequence of selecting the GD option is that
high-pressure gas at around 350 bar will be required
so an additional compressor is needed to boost the
fuel pressure from its normal 20-40 bar. Although
this gas compressor section is a relatively expensive
component, its cost is offset by the flexibility of being
able to switch fuels.
The gas fuel system supplies GD engines with clean
gas at constant pressure and temperature. The main
components of the system are a gas compressor skid
a buffer tank, a valve station, interconnecting
pipes
and double-wall ventilation system.
Avoiding plant downtime
The main challenge when performing conversion work
is minimizing the impact on normal plant operation.
Activities are therefore timed to coincide with regular
maintenance work, i.e. when the engines have been
stopped for their 24,000-hour
overhaul.
The installation of gas pipelines involves welding
operations
and pulling a variety of cables. One of
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gas involves replacing some engine components, with
balancing plant operation requirements
against the
! the number of components being changed dependent
demands of the conversion work so that both run
on the equipment's age. The main change involves the
smoothly.
addition of a new gas-feed system together with changes
To keep plant downtime to a minimum, engines will
!
to the engine's control and monitoring systems. The
be converted one at a time. The gas systems will be
plant conversion process consists of modifications to
assembled while the engines are running on HFO and
gas handling systems and control systems.
then swapped over as gas becomes available. According
WartsiIa
offers three types of gas conversion
to the IPP's power purchase agreements, each of the
technology: gas diesel (GD); low-pressure natural gas
three plants is contracted to deliver 60-65 MW This
(SG) and dual-fuel (DF). All three Manaus plants will
means that only four out of the five engines at each
undergo GD conversions. Gas diesel technology is
plant are in continuous operation, with the fifth engine
based on the injection of natural gas at high pressure
on standby. Conversion work can therefore be carried
as part of the diesel cycle, which means that engine
out on the standby engine.
modifications are limited to the injection equipment
and associated control systems.
Largest project to date
The resulting GD engine is a dual-fuel device designed
With a combined value of more than EUR 48 million,
to operate in two fuel modes. In the liquid-fuel mode,
these three plant conversions represent the biggest
LFO, HFO or crude oil is used as the main fuel and
project of its kind ever undertaken by Wartsila Services.
Its size and scope, together with the fact that the work
the engine operates on the ordinary diesel cycle. In gasfuel mode, natural gas is the main fuel and ignition is
is to be carried out at three separate sites, make it an
performed using a small quantity of liquid fuel.
interesting challenge.
Gas pipelines are now under construction and gas is
expected to be available in 200912010. This will allow
Extra compression required
pre-commissioning of the first units to begin during the
Prior to conversion, WartsiIa 18V 46 engines have a
second quarter of201O.The three plants are scheduled
single fuel-feed system located at the top of the engine
cylinders. This handles the liquid fuels (HFO or LFO).
to be fully operational in October 2010 .•
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