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Function of condenser in a feed system for boiler and steam turbine
The condenser is a heat exchanger which removes the latent heat from
exhaust steam so that it condenses and can be pumped back into the
boiler. This condensing should be achieved with the minimum of
under-cooling, i.e. reduction of condensate temperature below the
steam temperature. A condenser is also arranged so that gases and
vapours from the condensing steam are removed.
An auxiliary condenser is shown in Figure below. The circular
cross-section shell is provided with end covers which are arranged for a
two-pass flow of sea water. Sacrificial corrosion plates are provided in
the water boxes.
The steam enters centrally at the top and divides into
two paths passing through ports in the casing below the steam inlet
hood. Sea water passing through the banks of tubes provides the cooling
surface for condensing the steam.
The central diaphragm plate supports
the tubes and a number of stay rods in turn support the diaphragm
plate. The condensate is collected in a sump tank below the tube banks.
An air suction is provided on the condenser shell for the withdrawal of
gases and vapours released by the condensing steam.
Fig:Auxiliary feed system
Main condensers associated with steam turbine propulsion machinery
are of the regenerative type. In this arrangement some of the steam
bypasses the tubes and enters the condensate sump as steam. The
condensate is thus reheated to the same temperature as the steam, which
increases the efficiency of the condenser. One design of regenerative
condenser is shown in Figure .
A central passage enables some of the
steam to pass to the sump, where it condenses and heats the condensate.
A baffle plate is arranged to direct the gases and vapours towards the air
ejector. The many tubes are fitted between the tube plates at each end
and tube support plates are arranged between. The tubes are circulated
in two passes by sea water.
The feed system completes the cycle between boiler and turbine to
enable the exhausted steam to return to the boiler as feedwater. The arrangements for steam recovery from auxiliaries and ship services
may form separate open or closed feed sysems or be a part of the main
Summarized below more guidance for marine feed system:
Open feed system for an auxiliary boiler - how it works
In open feed system for an auxiliary boiler , the
exhaust steam from the various services is condensed in the condenser.
The condenser is circulated by sea water and may operate at
atmospheric pressure or under a small amount of vacuum. The
condensate then drains under the action of gravity to the hotwell and
feed filter tank....
- Closed feed system for an auxiliary boiler - operating principle
A closed feed system for a high pressure watertube boiler supplying a
main propulsion steam turbine is shown in Figure above.
The steam turbine will exhaust into the condenser which will be at a
- How De-aerator works in a boiler feed system
The de-aerator completes the air and vapour removal process begun in the condenser. The condenser is a heat exchanger which removes the latent heat from exhaust steam so that it condenses and can be pumped back into the boiler
- Heat exchangers in a boiler feed system /steam turbines
The gland steam condenser, drains cooler and low-pressure feed heater
are all heat exchangers of the shell and tube type. Each is used in some
particular way to recover heat from exhaust steam by heating the
feedwater which is circulated through the units.
Auxiliary Feed systems for boilers and steam turbines
Where, for instance, steam-driven deck auxiliaries are in use, a
separate auxiliary condenser operating at about atmospheric pressure
will condense the incoming steam . An extraction pump will
supply the condensate to an air ejector which will return the feedwater
to the main system at a point between the gland steam condenser and the
Boiler feed operation and maintenance
Extraction pumps should be checked regularly to ensure that the
sealing arrangements are preventing air from entering the system. It is
usual with most types of glands to permit a slight leakage of water to
ensure lubrication of the shaft and the gland.
- Function of High pressure feed heater
The high-pressure feed heater is a heat exchanger of the shell and tube
type which further heats the feedwater before entry to the boiler.
Further heat may be added to the feedwater without its becoming steam
since its pressure has now been raised by the feed pump.....
Sea water circulation of coolers for lubricating oil, piston cooling, jacket water, charge air, turbo-charger The usual arrangement for motorships has been to have sea-water circulation of coolers for lubricating oil, piston cooling, jacket water, charge air,
turbo-charger oil , fuel valve cooling, plus direct sea-water cooling for air compressors and evaporators.....
- Feed extraction pump - working procedure
The extraction pump is used to draw water from a condenser which is under vacuum.The pump also provides the pressure to deliver the feed
water to the de-aerator or feed pump inlet.
- How an air ejector works in a boiler feed system The air ejector draws out the air and vapours which are released from the condensing steam in the condenser. If the air were not removed
from the system it could cause corrosion problems in the boiler. Also, air
present in the condenser would affect the condensing process and cause
a back pressure in the condenser.....
- Function of condenser in a feed system for boiler and steam turbine The condenser is a heat exchanger which removes the latent heat from exhaust steam so that it condenses and can be pumped back into the
boiler. The feed system completes the cycle between boiler and turbine to enable the exhausted steam to return to the boiler as feedwater.
Marine machineries - Useful tags
Marine diesel engines ||Steam generating plant ||Air conditioning system ||Compressed air ||Marine batteries ||Cargo refrigeration ||Centrifugal pump ||Various coolers ||Emergency power supply ||Exhaust gas heat exchangers ||Feed system ||Feed extraction pump ||
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