INPLANT TRAINING REPORT
CONDENSER Condenser is an equipment working under vacuum, which
is
used
to
condense
exhaust
steam
from
steam
turbine to re-use in power plant cycle.
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CONDENSER - FUNCTIONS
Primary Functions:-
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Provide minimum temperature heat sink in the plant.
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Condense exhaust steam from turbine.
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Maintain constant back pressure at turbine exhaust, for
optimum turbine efficiencies. \
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Secondary Functions:-
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Deaeration of condensate / make-up water.
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Removal of non-condensables.
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Provide storage capacity of condensate.
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Act as receiver of system drains.
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FEATURES OF GOOD CONDENSER DESIGN
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Lowest back pressure for condensing surface provided.
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Return
condensate
to
cycle
at
the
highest
possible
reduce
system
temperature (i.e. minimum subcooling). \
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Remove
oxygen
from
condensate
to
corrosion. \
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Maximum venting of insoluble gases.
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Uniform pressure drop through any section of condenser.
V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
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MAIN PARTS OF CONDENSERS
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Shell. 0 Hotwell.
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Exhaust hood.
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Tube-sheet & baffle plates.
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Condensing Tubes.
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Inlet & Return Water Box.
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Condenser Shell Section where condensation of steam over tubes
takes place. \
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Consist of :-
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Shell side construction.
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Tube Bundle.
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Tube sheets.
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Support Plates.
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Air Removal Section. \ue000
Condensers
outermost
body
containing
heat
exchanger tubes. \ue000
Fabricated from C.S plates & stiffened as needed to
provide rigidity for the shell. \ue000
Baffles are inserted as intermediate plates that
provide the desired flow path for the condensing steam & provide support that prevents sagging of long tubes. \ u e 0 0 1 V .J .T. I , MATUNGA
Tube sheets Page 70
INPLANT TRAINING REPORT
At
each
end
of
the
shell,
sufficient thickness usually made of
a
sheet
of
stainless steel is
provided, with holes for the tubes to be inserted and rolled. \ue000
Hold tubes firmly.
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Separate shell from water boxes.
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Tubes Tubes are made of
stainless steel, copper alloys
such as brass or bronze,
cupro
nickel, or titanium
depending on several selection criteria. \ue000
Use of copper bearing alloys such as brass or cupro
nickel is rare in new plants, due to environmental concerns of toxic copper alloys. \ue000
Titanium tubes are usually the best technical choice,
however the use of titanium condenser tubes has been virtually eliminated by the sharp increases in the costs for this material \ue000
The tube lengths range to about 55 ft (17 m) for
modern power plants, depending on the size of the condenser. The size chosen is based on transportability from the manufacturers\u2019 site and ease of erection at the installation site. \ue000
The outer diameter of condenser tubes typically
ranges from 3/4 inch to 1-1/4 inch, based on condenser V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
cooling
water
friction
considerations
and
overall
condenser size.
Condenser Water boxes. The
tube
sheet
at
each
end
with
tube
ends
rolled, for each end of the condenser is closed by a fabricated box cover known as a water box, with flanged connection to the tube sheet or condenser shell. Receives & delivers cooling water to Circulating water system. Inlet
Water
box:
Receives
cooling
water
from
circulating water system in the plant & passes the water to the tubes. Outlet Water box: Receives water from the tubes & delivers to the circulating water system. Return Water box: Acts as transition piece between two passes in case of multi-pass condensers. The water box is usually provided with many holes on hinged covers to allow inspection and cleaning. Inlet Water Boxes will also have flanged connections for cooling water inlet
butterfly valves, small vent pipe
with hand va lve for air venting at higher level, and hand operated drain valve at bottom to drain the water box for maintenance. Similarly on the outlet water box the cooling water connection will have large flanges,
butterfly valves, vent
connection also at higher level and drain connections at lower.
V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
Hotwell Hotwell hangs at the bottom of the shell to collect the condensate water.
Air-removal Section
Removes accumulated air & non-condensable gases. Isolation of section of tubes.
Support Plates
Provides supporting structure to tubes. Minimizes tube vibration. Provides additional stiffening to shell from inside.
Condenser Support
Circular condensers are supported on saddles. Rectangular condensers are directly mounted on hot
well bottom plate.
Baffles:
Baffles are the metallic plates with holes or
corrugated strips for the tubes support. It also diverts the shell side fluid and gives it the required
number of passes.
The clearance between the shell and baffles and tubes and baffles must be minimum required; it avoids the bypassing of fluid. However the clearance should be enough to permit the insertion of tubes into baffles and the insertion of whole tube bundle into shell. Baffles in steam generator are made up of Inconnel strips. These are designed so to, provide a free flow of secondary sodium. V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
These are aluminized to prevent damage of tube outer surfaces.
MATERIAL OF CONSTRUCTION Typical Materials used in construction of Condensers.
Stainless Steel
Tubes
-A213 TP304,316
Al. Brass
- B111 C44300
Al. Brass
- B111 C68700
Al. Bronze
- B111 C60800
Cupro-Nickel
- 90:10, 70:30
Titanium
- B338 Gr.1,2
•
•
•
•
•
Carbon Steel
Pipes •
Boltings
V .J .T. I , MATUNGA
- A106 Gr.B
Stainless Steel - A312 TP304,316
High Tensile
- A193, A194
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INPLANT TRAINING REPORT
CONDENSER – TYPES
Direct Contact Condenser
Surface Condenser
V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
Based on Number of Passes
Single Pass.
No Divisions.
Double Pass.
Single Divisions.
Based on Number of Pressure Zones
Single Pressure.
V .J .T. I , MATUNGA
Dual Pressure.
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INPLANT TRAINING REPORT
Based on Steam Entry Location
Vertical Entry
V .J .T. I , MATUNGA
Side Entry
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INPLANT TRAINING REPORT
SURFACE CONDENSER - OPERATION Condenser Start-up
Ensure readiness of Auxiliary Equipment like CEP,
evacuation system etc, for start-up. Shell side water fill-up test & tube side hydro test. Fill hot well up to NWL with make-up water and prime the CEP lines. Circulate cooling water. Start Air Evacuation System. When
condenser
pressure
reaches
the
desired
value, condenser is ready to receive steam from turbine exhaust.
Condenser Normal Operating Mode No dump steam.
Condenser operating at designed parameters.
Condenser Abnormal Operating Mode Steam Dump Operation. Higher Back Pressure.
Condenser Shut-Down
All flows to condenser stopped. Shut down Air Evacuation System. Condenser vacuum to be broken using vacuum
breaker. After shell side is cooled down, shut down circulating water pump.
CONDENSER MAINTENANCE
V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
Periodic Inspection of Condenser. Accumulation of Debris, Scale Deposit inside Waterbox & Tubes. •
Mechanical Cleaning.
•
On-Line Tube cleaning System.
Cathodic Protection Anode Check. Waterbox painting check. Gasket replacement. Tube Failure. •
Plugging of Tubes.
Schedule of Preventive Maintenance. •
•
Every shut-down. Once in six month.
Condenser Protection during shut-down.
Deviation & their causes Low Vacuum. •
Primary Causes of Low Vacuum.
Air leakage. Poor Heat Transfer. Faulty Air Removal System. Tube Leakage. •
•
Tube Rupture. Tube to tube sheet joint failure.
V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
Air Leakage. •
Locations.
Bolted Joints. CEP shaft seal leaks. Piping Valve Stem leaks. Weld Cracks. •
Air Leak Detection.
Water Fill Test. Soap bubble Test. Flame test. Poor Heat Transfer. •
Low Quantity of Circulating Water.
•
Air Blanketing of Tubes.
•
High Circulating Water Inlet Temperature.
•
Scale Built-Up. Faulty Air Removal System.
•
Mal-functioning of Air Extraction Equipment.
•
Internal Damage to Air Cooler Zone.
•
Improper routing of Air Extraction Piping. Tube Leakage
•
Tube Rupture.
•
Tube to Tube sheet joint leakage.
•
Can be detected using pH / conductivity analyzers.
•
Tube Plugging.
V .J .T. I , MATUNGA
Page 80
INPLANT TRAINING REPORT
L&T CONDENSERS FEATURES OF L&T CONDENSER Tube
layout
resulting
into
low
pressure
drop,
minimum sub-cooling, maximum reheating of condensate.
V .J .T. I , MATUNGA
Page 81
INPLANT TRAINING REPORT
Minimum steam travel distance across the tube bundle. Structural
arrangements
designed
to
minimize
obstructions in the high velocity steam paths assure minimum back pressure. Centrally located and enclosed zone with ample heat
transfer
surface
effectively
cools
and
removes
paths
promote
noncondensables from the tube bundle. Equal
Tube
Bundle
penetration
effective use of all condensing surfaces. Full peripheral entry of steam results in low entry velocities and negligible pressure drops. Internal provisions to reheat & deaerate the drains. Steam
dump
system
designed
to
effectively
introduce and distribute large quantities of steam. Optimum design velocities within shell as well as tubes. Use of sacrificial anodes resulting in minimum corrosion of water boxes.
Fabrication sequence for circular condenser Shell assembly. Both side annular ring and shell nozzle set up. V .J .T. I , MATUNGA
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INPLANT TRAINING REPORT
Hot-well and saddle set up. One side tube sheet set up. Baffle insertion and alignment. Air hood set up & deflector. Tubing. Second side tube sheet set up. Expansion from one side. Second side trimming and expansion. Inlet/outlet & return water-box set up. Shell side hydro. Tube side hydro. Shot blasting and painting.
WHY CONDENSER OPERATES AT VACUUM?
As the operating pressure of condenser is reduced, enthalpy drop of the expanding steam in turbine will increase. This will also increase the amount of available work from the turbine. By lowering condenser pressure, following will occur
Increased turbine output. Increased plant efficiency.
V .J .T. I , MATUNGA
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