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Fuel Oil and Fuel Firing System
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Transcript of Fuel Oil and Fuel Firing System
A presentation on
FUEL OIL & FUEL FIRING SYSTEM)
Fuel Oil
Three liquid fuels used in power plantsHeavy Fuel Oil (HFO)LSHS (Low Sulfur Heavy stock)Light Diesel Oil(LDO)
Oil firing is preceded byLowering viscosity and increasing flowability on heating for better combustion in given turn down ratio.(125oC)Droplet formation on atomization (by steam/ compressed air/ mechanical pressurization) Combustion initiation by High energy spark ignition
Method of firing
Down shot firingFront fired
Single wallOpposed wall
Corner fired Tangential tilted
(-30o to +30o)Fluidized bed combustion
For Anthracite (Low VM)Bituminous (High/ medium VM)
Bituminous (Medium VM)
Lignite, peat, garbage (For low CV, high ash, high Sulphur)
Coal for combustionAnthraciteSemi-anthraciteBituminousSemi-BituminousLignitePeat
High CV, low VM High CV, low VM Medium CV, medium VM Medium CV, medium VM Low CV, high VM, high TM Very low CV, high VM & TM
Combustion air arrangement in furnace
Fuel air is supplied around coal nozzles (at velocity of 30-35 m/sec).
Secondary air is supplied in adjacent tiers of sec. air dampers from wind box (Hot air from Secondary APH)
Overfire/ Tempering air is supplied at the top of the burner zone for NOx control.
Gas recirculation is adopted for steam temperature control in oil/ gas fired units.Furnace draft is maintained at -5 mmwc with Forced and Induced draft fans (balanced draft)
Tangential corner fired boilers
Suitable for sub bituminous and bituminous coalMore uniform heat absorption in furnace wallsInherent feature of low NOx formation due air deficit region at centreAir plenum near walls reduce slagging and prevent fireside corrosion.Arrangement of steam temperature control by tilting the coal burners (-30o to +30o)
Flame visualization in tangential corner fired boilers
Burner tilt (UP) Burner tilt (Horizontal) Burner tilt (Down)
Optimization ofOptimization of total air supplytotal air supply
Boi
ler l
oss %
CO2%
Variation of CO with O2 in flue gas
Fuel Firing System
Burners Coal Fuel oil Light oil Igniters (HFO) (LDO) a)Quantity, 24 12 4 4 C)Atomization (Steam) (Air)
Heat loss Vs Excess air
40
30
20
10
20 40 60 80 100 % of excess air
Excess air for minimum loss
PF firing 20%Oil firing 10%
FUEL OIL SYSTEM
• STORAGE TANK DATA
• Description HFO Tank LDO Tank • Capacity(m3/hr) 2000 1000 • Numbers 2 1 • Tank size 16IDX12H 12IDX10H
UNLOADING PUMPS
• Description • Wagon unloading pumps• Service HFO/LSHS LDO • No's (4+2) (2+1) • Type Twin Screw Twin Screw • Capacity (150+25) (25+10)
FUEL OIL CHARACTERISTICS
LDO /HFO ANALYSIS
Combustion airTheoretical air for complete combustion is known as stoichiometric air.Excess air for completion of combustion (20% at MCR i.e. 3.6% O2)
Total combustion is divided asPrimary air For drying & pulverized coal transportationSecondary air Additional air for combustionRatio of SA/ PA = 2:1 (Approx)
%21%
2
2
OOExcessAir
QUESTIONS