CFBC boilers operate at high temperatures of 850-900 degrees Celsius and velocities of 4-7 meters per second. They allow for the combustion of low-grade fuels like coal rejects, rice husk, and wood chips. In a CFBC boiler, fuel particles are suspended in a bubbling fluidized bed and burned using a mixture of air injected from below. Ash and partially burned fuel circulate and re-burn, improving efficiency. CFBC boilers have advantages like high fuel flexibility, reduced emissions, and simpler operation compared to traditional boilers.

1. CFBC BOILER

2. Presentation on basics of CFBC BOILER

3. What is CFBC?
• It stands for Circulating Fluidized Bed Combustion.
• Fuel particles are suspended in a hot , bubbly fluidy
bed of ash ( containing sand / limestone) through
which nozzles of air are provided for combustion.
• Operating at high flue gas velocities 4 to 7 m/sec.
• Used for low capacity of plant 100 MW , 200MW .
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4. Why CFBC ?
• Fast and intimate mining of gas and solids promotes rapid
heat transfer and chemical reaction within the bed.
• Fuel burnt in these boilers include coal , washery rejects ,
rice husk , wood chips and other agricultural wastes at
high efficiency .
• These boilers are burnt at 850 – 900 degree C.
• These boilers uses crushed coal 3-6 mm of size, so no
pulverize is required.
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5. Basic Flow Diagram Of CFBC
Boiler
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6. Plant Overview
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7. Parts Of CFBC Boiler
• FLUIDIZED BED
• CIRCULATION
• BED MATERIAL
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8. Fluidized Bed
 At bottom of the boiler furnace there is a bed inert material
 Air supply is from under the bed at high pressure . This lift the bed
material and coal particles . Then the coal combination takes place
This is fluidized bed.
 Combustion air is supplied in CFBC boiler at 2 levels
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9. •60% at bottom of combustor at high pressure to fluidized bed.
40% in freeboard to complete combustion.
•SA fan – preheating combustion air
•PA fan – preheating fluidized air

10. Circulation
• Fine particles of partly burned coal ,ash and bed material are
carried along with the flue gases to the upper areas of furnace
and then to cyclone.
• In cyclone heavy particles separate from the gases due to
centrifugal force and falls on the cyclone hoppers .
• This returns to the furnace for re-circulation. So the thermal
efficiency of plant increase.
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11. FBHE Fluidized bed heat exchanger
• It is 4 rooms structure containing –
 1 Evaporator
 2 Super heater A
 3 Super heater B
 4 Re heater
• Elimination of heat transfer bundle in combustor.
• Very low carbon in ash and limestone consumption.
• Better fuel flexibility due to provision for adjusting heat
absorption. 11

12. Features of CFBC
• Taller boiler structure
• Coal is crushed to a size of 3-6 mm of size depending on the rank of coal
• The fluidizing velocity in circulating beds ranges from 4-7 m/sec
• Combustion efficiency is 99.5%
• Combustion takes place at 850-900 degree c.
• There are no steam generators tubes immersed in the bed.
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13. Advantages
• High Efficiency
• Combustion efficiency 95%
• Overall operating efficiency 88%
• Fuel flexibility
• Ability to burn low grade fuel
• Pollution control
• Sox formation is minimized by adding limestone
• low combustion temperature eliminates Nox formation.
• Easier ash removal – no clinker formation.
• Simple operation , quick start up
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14. Advantages cont…
• No slag in furnace – no soot blowing
• High reliability and low maintenance cost .
• Auxiliary power reduction by eliminating the flue gas
de sulphurisation FGD .
• Can use different types of solids fuels.
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15. THANK
YOU