Large rotating equipment and the generators are driven by gas turbines or large
drives. Gas turbines for oil and gas duty are generally modified aviation turbines in
the 10-25 MW range. These require quite extensive maintenance and have a
relatively low overall
efficiency (20-27% depending
on application). Also, while
the turbine is relatively small
and light, it will usually
require large and heavy
support equipment such as
large gears, air coolers/filters,
exhaust units, sound damping
and lubrication units.
Therefore use of large variable
speed drives is becoming more
common. For pumps on
Subsea facilities this is the only option. For use on remote facilities, High Voltage
DC transmission and HV motors can be used, from a main facility or power from
shore. This will also avoid local power generation at each facility and contribute to
low manning or remote operation.
5.3 Flare and Atmospheric Ventilation
The flare subsystem include Flare,
atmospheric ventilation and blow down. The
purpose of the Flare and Vent Systems is to
provide safe discharge and disposal of gases
and liquids resulting from:
· Spill-off flaring from the product
stabilisation system. (Oil, Condensate
etc.).
· Production testing
· Relief of excess pressure caused by
process upset conditions and thermal
expansion.
· Depressurisation either in response to
an emergency situation or as part of a
normal procedure.
· Planned depressurisation of subsea production flowlines and export
pipelines.