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Processes >
Midstream >
LNG Production >
E-LNG >
Power generation
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Water-steam cycles
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Gas turbines
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Steam turbines
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Synchronous generators
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Power transmission and distribution
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Stability
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Power generation - Water-steam cycles
Heat from gas-turbine exhausts is very effectively used to
generate high-pressure steam for combined-cycle use and
low-pressure steam for process use. Based on well-proven
standards and modular concepts, Siemens designs the entire
water-steam cycle to provide safe, reliable, and efficient
operation, and an optimum match of capital cost and plant
performance.
 Making the most out
of the feedstock,
water-steam cycles
enable power plants
to achieve efficiencies
of up to 52 percent.
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Focused on flexibility
E-LNG power plants operating in island mode have to
meet varying steam and load requirements. To boost steam
production in the event of low electrical power demand,
the heat-recovery steam generator (HRSG) can be supported
by supplementary firing. The electrical load is then
largely decoupled from steam production. Depending on
the chosen plant concept, the HRSG generates steam of
different pressure levels and condensate preheating. With
space available, Siemens uses horizontal drum-type boilers
with natural circulation. The HRSGs can be equipped with
exhaust-gas bypass stacks and diverter dampers to allow
switching from combined-cycle to single-cycle operation to
increase operational flexibility. Meeting zero-discharge
requirements, steam produced by the HRSGs is routed to
common headers and distributed to either the steam turbines
and/or the process heating system. A steam regulating
station meets varying steam demand. Exhaust steam
from the steam turbines is typically liquefied in air-cooled
condensers, and the condensate is fed to de-aerators to
provide condensate qualities for long lifetime operation.
Liquid losses can be reduced to keep the size of make-up
water plants small.
Redundancy for maximum availability
Deaerated condensate is pumped to common headers to
allow for individual adjustment of multiple units but still
using standardized HRSG designs. Redundant feed-water
pumping systems ensure maximum availability. The information
and control system also follows the redundancy
concept of the entire power scheme. HRSGs are available
for outdoor installation with combined heat and noise
insulation, or for installation in a boiler house. Closed cooling
loops with redundant circulation pumps and forceddraft
fin-fan cooler banks transfer heat losses of generator
and motor cooling water to the ambient air by virtually
maintenance-free and highly reliable autonomous subsystems. |
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