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