Power Plant Engineering: – Fluidized Bed Combustion

What is Boiler means?

Boiler is vessel, which always works under pressure.

As per ” The Indian Boilers ACT2007,

Boiler means any closed vessel or any shaped but closed, exceeding in mentioned capacity which is used expressly for generating stream under desired pressure and includes any mountings or other fitting attached to such vessel for improving efficiency, which is wholly or partly under pressure when steam is in the system.

The heated or vaporized fluid (includes water and gas) exits the boiler for use in various processes or heating application. I.e steam turbine, gas turbine……

What is Fluidized bed combustion (FBC)?

• Fluidized bed combustion (FBC) is combustion technology used to burn solid and also powder form of fuels.
• In its most basic form, fuel particles are suspended in a hot, bubbling fluidity bed of Ash and other particulate materials (sand, coal, limestone etc.) Through which jets of air are blown to provide the (O²)oxygen, which is required for combustion of fluid or gasification. The resultant fast and intimate mixing of gs and solids promotes rapid heat transfer and chemical reactions within the bed.
• There is Coal and limestone feed in for Combustion.
• From air preheater, preheated air forced to fluidizing air helps to burn fluid.
• So, steam is generating throughout the all systems.

Characteristics Of Fluidized Bed

• Fluidization depends largely on the particles size and the air velocity.
• In FBC, turbulence is promoted by fluidization in system.
• If sand particles or in form of powder in a Fluidized state is heated to the ignition temperatures of burning input as coal, the coal will burn rapidly as compared and bed attains or gains a uniform temperature.
• The Fluidized bed Combustion (FBC) takes pace at about 842°C to 952°C. Since this temperature is much below the required to Ash fusion temperature, melting of Ash ad associated problems are to be avoided.
• Limestone is generally used as particle bed, control of sulphur dioxide and also nitrogen oxide emissions in the combustion chamber.

Advantages:-

• There are two reasons for the rapid or quick increase of FBC (fluidized bed combustion) in combustors.
• The First is, the possibility of using fuels which are difficult to burn using other technologies and methods.
• The second reason during Combustion, a low emission of nitric oxides and the possibility of removing sulfur in a easy manner by using limestone as bed material.