Boiler Fundamentals

BOILER FUNDAMENTALS

PRINCIPLE OF COMBUSTION • CONVERSION OF CHEMICAL ENERGY TO HEAT ENERGY. • COMBINE CARBON AND HYDROGEN (HYDRO CARBONS) WITH OXYGEN. IGNITION

• RAISING THE TEMPERATURE OF THE FUEL TO IGNITION TEMP. THEORITICAL AIR & EXCESS AIR FACTORS FOR EFFICIENT COMBUSTION (3Ts) •TIME •TEMPERATURE •TORBULENCE

COMBUSTION EFFICIENCY

THERMAL EFFICIENCY= HEAT TRANSFERRED/1 KG OF FUEL USED. • DESIGN OF BOILER. • FUEL USED. • OBTAINING MINIMUM EXCESS AIR. BASIS OF BOILER CLASSIFICATION •USE (STATIONARY/MOBILE) •PRESSURE •MATERIALS •SIZE •TUBE CONTENT(FIRE TUBE/WATER TUBE)

•TUBE SHAPE AND POSITION •FIRING (FIRED/NONFIRED) •HEAT SOURCE •FUEL (COAL/GAS/NUCLEAR) •FLUID (WATER/MERCURY WATER) •CIRCULATIONS (NATURAL/FORCED) •FURNACE POSITION (INTERNAL FIRED/EXTERNAL FIRED) •FURNACE TYPE •GENERAL SHAPE •TRADE NAME •SPECIAL FEATURES (DIFFERENTIAL/HORIZONTAL/TANGENTIAL FIRING)

TYPES OF BOILER • STEEL BOILER

• SHELL TYPE

• FIRE TUBE TYPE

• CAST IRON BOILERS

• WATER TUBE TYPE

• SPECIAL DESIGN BOILERS

• HORIZONTAL STRAIGHT TUBE

• NUCLEAR REACTORS

• BENT TUBE

END USE

POSITIVE CIRCULATION

• UTILITY

• NATURAL CIRCULATION

• INDUSTRIAL

MAJOR ACCESSORIES • ECONOMISER

• PLATEN SUPERHEATERS

• BOILER DRUMS

• FINAL SUPERHEATERS

• DOWN COMERS

• REHEATERS

• WATERWALLS

• BURNERS

• PRIMARY SUPERHEATERS/LOW

• IGNITERS (EDDY PLATE/HIGH

TEMP SUPERHEATERS (LTSH)

ENERGY ARC)

ECONOMIZERS: THE ECONOMIZER IS THE HEAT EXCHANGER THAT RAISES THE TEMP. OF THE WATER LEAVING THE HIGHEST-PRESSURE FEEDWATER HEATER TO THE SATURATION TEMP. CORRESPONDING TO THE BOILER PRESSURE. THIS IS DONE BY GASES LEAVING THE LAST SUPERHEATER/REHEATER. GAS TEMP. AT ECONOMIZERS- 350 TO 375 C

BOILER DRUM: THE STEAM DRUM PROVIDED EXCEPT ONCE-THROUGH BOILER IS WHERE FEEDWATER FROM ECONOMIZER IS FED, SATURATED STEAM IS SEPARATED FROM THE BOILING WATER IS RECIRCULATED. THE DRUM IS ALSO USED FOR CHEMICAL TREATMENT AND BLOWDOWN TO REDUCE SOLIDS IN WATER.

DOWNCOMERS: DOWNCOMERS ARE PROVIDED UNDER THE DRUM WHERE THE SEPARATED WATER FROM STEAM AT BOILER DRUM COMES TO THE BOTTOM RING HEADERS & FROM WHICH IT ENTERS INTO THE WATER WALLS FOR THE FORMATION OF STEAM. WATER WALLS: IN WATER WALLS THE SEPARETD WATER FROM THE DRUM THROUGH BOTTOM RING HEADER CONVERTED INTO STEAM BY HEAT TRANSFER PROCESSES.

SUPERHEATERS AND REHEATERS: THE STEAM SEPARATED AT THE DRUM PASSES THROUGH THE SUPERHEATERS/REHEATERS THEREBY PICK UP ADDITIONAL HEATS FROM THE GASES BY CONVECTION & RADIATION. LTSH, LOW TEMP SUPERHEATERS DIVISIONAL PANEL PENDANT/FINAL SUPERHEATERS REHEATERS: IN REHEATERS THE HEAT IS TRANSFERRED FROM THE FLUE GASES TO THE USED STEAM FROM THE HP TURBINE THEREBY INCREASING THE EFFICIENCY.

OTHER IMPORTANT COMPONENTS: SUPERHEATER DESUPERHEATERS REHEATER DESUPERHEATERS WATER COOLED FURNACE WATERWALL INLET HDRS/BOTTOM RING HDR CHEMICAL DOSING SYSTEM (TSP)

FUEL FIRING SYSTEM: FUEL OIL SYSTEM COAL SYSTEM BURNERS/NOZZLES

TILTING TANGENTIAL FIRING SYSTEM: AIR & FUEL NOZZLES TILTS WIND BOX ASSEMBLY.

FUEL OIL FIRING SYSTEM: FUELS BURNER ARRANGEMENT COMBUSTION & DISTRIBUTION FURNACE PURGE BOILER LOW LOAD OPERATION BOILER LOAD ABOVE 30% FUEL AIR DAMPERS FUEL OIL ATOMISATION HFO RECIRCULATION

OIL FLOW CONTROL STEAM REQUIREMENT HFO BURNERS FUEL OIL PUMP IGNITORS FUEL OIL GUN ADVANCE/RETRACT MECHANISM STEAM SCAVENGING OF FUEL OIL GUNS HEAT TRACING OF HFO LINES HFO PUMPS & ACCESSORIES COAL FIRING SYSTEM: PULVERIZED COAL SYSTEM PULVERIZERS FEEDERS

PULVERIZED COAL DRYING COAL PIPING GRAVIMETRIC FEEDERS

AIR SYSTEM: AIR & GAS PATH SCANNER AIR FANS SEAL AIR FANS PRIMARY AIR/MILL SEAL AIR SYSTEM SECONDARY AIR SYSTEM/FORCED DRAUGHT FANS PRIMARY AIR FANS INDUCED DRAUGHT FANS AIR PREHEATERS (PRIMARY & SECONDARY) SOOT BLOWING SYSTEM (WATER WALL/LRSB/APH)