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boiler
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BOILER PRESSURE PARTS• COMPONENTS OF BOILER THROUGH
WHICH FEED WATER AND STEAM FLOW AND HEAT IS ADDED
• COMPONENT HEAT ADDITION
ECONOMISER 6%
DRUM NIL
WATERWALL 50%
SUPER HEATER 30%
RE HEATER 14%
BOILER PRESSURE PARTS LOCATION
ECONOMISER
• PRE HEATS THE FEED WATER ENTERING THE BOILER BY USING HEAT IN OUT GOING FLUE GASES– IMPROVES BOILER EFFICIENCY– REDUCE BOILER SIZE
ECONOMISER TYPES
PLAI N TU BE FI N N ED TU BE
TU BE DESI G N
N O N STEAM I N G STEAM I N G
H EAT ADDI TI O N
I N LI N E STAG G ER ED
AR R AN G EM EN T
ECO N O M I SER
COMPARISON OF ECONOMISER TYPES
• PLAIN TUBE– EASY ON LOAD
CLEANING
• FINNED TUBE– MORE HEAT
TRANSFER AREA IN GIVEN VOLUME
– ON LOAD CLEANING DIFFICULT
Direction of Gas Flow Direction of Gas Flow
Inline Arrangement Staggered Arrangement
COMPARISON OF ECONOMISER TYPES
• STAGGERED– HIGH HEAT
TRANSFER RATE DUE TO INCREASED TURBULANCE
– ON LOAD CLEANING DIFFICULT
• INLINE– EASY ON LOAD
CLEANING
ECONOMISER DESIGN CONSIDERATIONS
• OVERALL HEAT TRANSFER AREA OF ECONOMISER DEPENDS ON– FEED WATER INLET TEMPERATURE– SATURATION TEMP. CORRESPONDING
TO OPERATING PRESSURE– FEED WATER FLOW RATE– GAS TEMP. REQUIRED AT THE
OUTLET OF ECONOMISER
ECONOMISER DESIGN CONSIDERATIONS
• TUBE DIAMETER, LENGTH AND SPACING ARE DECIDED TO ENSURE– UNIFORM WATER FLOW THROUGH
ALL TUBES WITH LOW RESISTANCE– ECONOMISER FITIN WITH THE
DESIGN OF PRCEDING SECTION – DRAUGHT LOSS IS MINIMUM– PROVISON FOR ON LOAD CLEANING
DEVICE
LOCATION OF ECONOMISER IN A TWO PASS BOILER
ECONOMISER COIL INSIDE BOILER
ECONOMISER TUBE FAILURE
• OVER HEATING– STARVATION– SCALING
• CORROSION– INTERNAL– EXTERNAL
• EROSION
ECONOMISER RE CIRCULATION
DRUM CONSTRUCTION
FUNCTIONS OF BOILER DRUM
• TO SEPARATE WATER AND STEAM FROM WATER STEAM MIXTURE
• MIX WATER SEPARATED WITH WATER FROM ECONOMISER AND FEED TO DOWNCOMERS
• TO FACILITATE CHEMICAL DOZING
• TO FACILITATE BLOWDOWN
DRUM CONNECTIONS
STEAM SEPARATION IN DRUM
• GRAVITY SEPARATION– ADOPTED FOR
LOW PRESSURES
– USE BAFFLES TO CHANGE DIRECTION OF FLOW TO SEPARATE WATER BY GRAVITY
• CENTRIFUGAL AND GRAVITY SEPARATION– ADOPTED FOR
HIGH PRESSURES
– USE TURBO SEPARATORS OR CYCLONE SEPARATORS TO IMPART CENTRIFUGAL FORCES
GRAVITY SEPARATION USING BAFFLES
STEAM SEPARATION USING CYCLONE SEPARATORS
AUXILIARY CONNECTIONS TO THE BOILER DRUM
• CHEMICAL DOZING NOZZLE
• BLOWDOWN NOZZLE
• FOR THE MEASUREMENT OF PRESSURE AND TEMPERATURE
• WATER LEVEL INDICATORS
• SAFETY VALVES AND AIR VENTS
TAPPINGS FOR VARIOUS MEASUREMENTS ON THE DRUM
• THREE PAIRS FOR REMOTE LEVEL INDICATORS
• TWO PAIRS FOR LOCAL LEVEL GAUGES• TWO PAIRS FOR CONDUCTIVITY
MEASUREMENT• TWO PAIRS FOR PRESSURE
MEASUREMENT• THREE PAIRS OF THERMAL PADS FOR
MEASURING DRUM METAL TEMPERATURE
• ONE PAIR FOR HIGH LEVEL AND LOW LEVEL TRIPS
EFFECTS OF DRUM LEVEL VARIATIONS
• LOW LEVEL– STARVAION AND ULTIMATE FAILURE
OF WATERWALL TUBES
EFFECTS OF DRUM LEVEL VARIATIONS
• HIGH LEVEL– AFFECTS STEAM SEPARATION– CARRY OVER OF WATER BY STEAM
• SUPER HEATERS THERMALLY STRESSED
• SCALING IN SUPER HEATERS– OVER HEATING OF SUPER HEATERS
• WATER HAMMERING IN STEAM PIPES
• PITTING ON TURBINE BLADES
AIR VENT AND SAFETY VALVES