1. Government Engineering College Valsad

2. Prepared By ( 1 ) Shyora Kanti G. Enrollment No. = 130 190 105 103
( 2 )Singh Vivekkumar V.
Enrollment No. =
( 3 ) Solanky Akshay N.
Enrollment No. =
Chem. 2nd year , 3rd sem

3. Chemical Engineering Department
Submitted To
Prof. M. G. Desai
Chemical Engineering Department
For the Subject
Fluid Flow Operation
( )

4. To Study about fludization bed for coal fired boiler
Topic
To Study about fludization bed for coal fired boiler

5. Introduction
The major portion of the coal available in india is of low quality, high ash content and low calorific value.
The traditional grate fuel firing systems have got limitations and are technology unaviale to meet the challengs future.
Fluized bed combustion has energed as aviable alternative and has significent advantages over conventional firing system and offers multiple benefit compact boiler design,

6. Fuel flexibility , higher combustion efficiency and reduced emission of noxious pollutants such as SOx and NOx.
The furls burnt in these boilers include coal, washery rejects, rice husk, bagasse and other agricultural wastes.
The fluidized bed boilers have a wide capacity range 0.5 T/hr to other 100 T/hr.

7. Mechanism
When an evenly distributed air or gas is passed upward through a finely divided bed of solid particles such as sand supported on a fine mesh the particles are undisturbed at low velocity.
As air velocity is gradually increased, a stage is reched when the individual particles are suspended in the air stream the bed is called fluidized.

8. At higher velocities bubbles disappear and particles are blown out of the bed these fore some amounts of particles have to be recirculated to maintain a stable system circulating fluidised bed.
If sand particles in a fluidized state is heated to the ignition temp. of coal and coal is injected continuously into the bed the coal will burn rapidly and bed attains a uniform temp.

9. The fludized bed combustion takes place at about 840 oC to 950 oC
The fludized bed combustion takes place at about 840 oC to 950 oC. Since this temp. is much below the ash fusion temp. melting of ash and associated problems are avoided.
Combustion process require the three T is that is time temp. and turbulence. In FBC turbulence is promoted by fluidisation. Improved mixing generates evenly distributed heat at lower temp. Residence time is many times greater than conventional grate firing thus an FBC system.

11. Since limestone is used as particle bed control of sulfur dioxide and and nitrogen oxide emissions chamber is achieved without any additional control equipment. This is one of the major advantages over conveutional boilers.

12. Features
Burning efficiency reaches 95 % - 99% high burning rate heat efficiency above 87% energy saving , high efficiency.
High flexiblity of fuel which can satisfy the burning of many kinds of fuels.
High automatic control makes boilers running safely and economically in long term.

13. Limestone can be added in bed material during burning process reacts with SO2 of flue formulates sulphate desuphuration an satisfy which can control formalation of NOx and really reach environment protection big adjusting range load can be adjusted rang 110% - 30%.
Adopt upper exhaust high temp. cyclone separat device high collection of bed material high heat transfer co efficient high ability of overload.

15. Advantages
High efficiency : FBC boilers can burn fuel with a combustion efficiency of over 95% irrespective of ash content. FBC boiler can operate with oveall efficiency of 84%.
Reduction in boiler size : High heat transfer rate over a small heat transfer area in the bed result in overall size reduction of the boiler.

16. Ability to burn fines : Coal containing fine below 6 mm can be burnt efficiency in FBC boiler which is very difficult to achieve in conventional firing system.
Low corrosion and erosion : The corrosion and erosion effects are less due to lower combustion temp. softness of ash and low particle velocity.
High Reliability : The absence of moving parts in the combustion zone results in a high degree of reliability and low maintenance costs.

17. Fast response to load fluctuations : In herent high thermal storage characteristics an easily absorb fluctuation in fuel feed rates. Response to changing load is comparable to that of oil fire boilers.

18. THANK YOU…