1. FLUIDISATION BED COMBUSTION (FBC) BOILERSBY
ISAAC JOHN
GUIDE
PROF : XYZ

2. INTRODUCTION Viable alternative Multiple benefits
compact boiler design, fuel flexibility,
higher combustion efficiency and reduced emission of pollutants SOx and NOx.
Fuels
coal, washery rejects, rice husk, bagasse & other agricultural wastes.
Capacity range- 0.5 T/hr to over 100 T/hr.

3. HISTORY: A NEW WAY TO BURN
0ne afternoon more than a decade ago, a British engineer named Douglas Elliott tapped a bit of coal, ground to crumbs in a kitchen blender, into a tin can mounted on the wall. Below the can was an ordinary small open fireplace – ordinary, that is, at a casual glance.
For instead of burning coals, a red- hot bed of sand gently undulated like simmering lava. As the coal trickled out of the can onto the glowing bed below, each crumb exploded into flame with a pop and a blue-white flare. It burned only about two pounds of coal an hour, but the little fireplace glowed fiercely, delivering much more warmth than its size suggested.

4. FLUIDISATION
The operation through which fine solids are transformed into a fluid like state through contact with either a gas or a liquid.
A process similar to liquefaction whereby a granular material is converted from a static solid-like state to a dynamic fluid-like state. This process occurs when a fluid (liquid or gas) is passed up through the granular material.

5. MECHANISM OF FLUIDISED BED COMBUSTION

6. TYPES OF FLUIDISED BED COMBUSTION BOILERS
There are three basic types of fluidized bed combustion boilers:
1.Atmospheric classic Fluidized Bed Combustion System (AFBC)
2.Atmospheric circulating (fast) Fluidized Bed Combustion system (CFBC)
3.Pressurized Fluidized Bed Combustion System (PFBC)

7. ATMOSPHERIC FLUIDISED BED COMBUSTION SYSTEM (AFBC)
Crushed coal size 1 – 10 mm
Velocity of fluidising air –
1.2 to 3.7 m /sec.
Narrow temperature range - 800oC to 850oC.
Unit Size-25MWe
Thermal Efficiency-30%

8. GENERAL ARRANGEMENTS OF AFBC BOILERS
AFBC boilers comprise of following systems:
Fuel feeding system
Under bed pneumatic feeding
Over bed feeding
ii) Air Distributor
iii) Bed & In-bed heat transfer surface
iv) Ash handling system
Bottom ash removal
Fly ash removal
Many of these are common to all types of FBC boilers

9. CIRCULATING FLUIDISED BED COMBUSTION SYSTEM (CFBC)
Crushed coal size 6 – 12 mm
Velocity of fluidising air –
3.7 to 9 m/sec
Solid recycle – 50 to 100 kg per kg of fuel burnt
Unit Size MWe
Thermal Efficiency-40%

10. PRESSURISED FLUIDISED BED COMBUSTION SYSTEM (PFBC)
Temperature – 860 C
Pressure bars
Flue gases expanded in gas turbine
Used for cogeneration
Unit Size-80MWe
Thermal Efficiency-40%

11. RETROFITTING OF FBC SYSTEMS TO CONVENTIONAL BOILERS
Retrofitting fluidized bed coal fired combustion systems to conventional boilers has been
Carried out successfully both in India and abroad.
The important aspects to be considered in retrofit projects are:
a) Water/steam circulation design
b) Furnace bottom-grate clearance
c) Type of particulate control device
d) Fan capacity
e) Availability of space.

12. COMPARISON BETWEEN STOKER AND FLUIDISED BED COMBUSTION
COMPARISON BETWEEN STOKER AND FLUIDISED BED COMBUSTION
S.No
STROKER
FBC 1
TRAVELLING/FIXED
GRATE
FLUIDISED BED WITH AIR BOX
SYSTEM 2
BED EVAPORATER IS
NOT APPLICABLE
BED EVAPORATER WILL BE
INTRODUCED 3
BED SUPER HEATER
IS NOT APPLICABLE
BED SUPER HEATER SHALL
BE INTRODUCED 4
ONLY OVER BED
FEEDING SYSTEM
UNDER/OVER BED FEEDING
SYSTEM IS POSSIBLE 5
BED ASH HOPPER
WITH SUBMERGE
BELT CONVEYOR
BED ASH DRAIN WITH
COOLER AND PNEUMATIC /
MECHANICAL CONVEYING 6
PRIMARY AIR SYSTEM
PRIMARY AIR SYSTEM IS
REQUIRED FOR FUEL
TRANSPORTION IN TO BED

13. ADVANTAGES OF FBC BOILERS
1. High Efficiency
2. Reduction in Boiler Size
3. Fuel Flexibility
4. Ability to Burn Low Grade Fuel
5. Ability to Burn Fines
6. Pollution Control
7. Easier Ash Removal – No Clinker Formation
8. No Slagging in the Furnace-No Soot Blowing
9. Provisions of Automatic Coal and Ash Handling System
10.High Efficiency of Power Generation

14. CONCLUSIONS
Decreasing electricity prices and improving environmental protection
Clean energy
More flexible than conventional plants
Reduced emissions and Improved combustion
Research and development is required in order to improve the FBC technology.

15. THANK YOU