BOILER PRESSURE PARTS

• COMPONENTS OF BOILER THROUGH WHICH FEED WATER AND STEAM FLOW AND HEAT IS ADDED

• COMPONENT HEAT ADDITIONECONOMISER 6%DRUM NILWATERWALL 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