“ Start with the name of Allah who is the Most Beneficent and Most Merciful.”

In the respect of

Sir Kashif Hussain Mangi Sir Kashif Hussain Mangi

Ihsan Ali Wassan Ihsan Ali Wassan (14ch18)

DISCIPLINE:CHEMICAL ENGINEERINGCHEMICAL ENGINEERING

SUBJECT:UNIT OPERATION-II UNIT OPERATION-II

QUAID-E-AWAM UNIVERSITY OF ENGINEERING, SCIENCE & TECHNOLOGY

NAWABSHAH, SINDH PAKISTAN

Boiler & Its Boiler & Its TypesTypes

PRESENTATION OUTLINESPRESENTATION OUTLINES

What is a Boiler? What should characteristics of boiler? Sources of heat in boiler? Types of Boiler Conclusion

What is a Boiler?What is a Boiler?

• A closed vessel made up of steel to transfer heat produced by combustion of fuel to water and ultimately generate steam .

It may be defined as: A steam generator or boiler is usually a closed vessel

made of steel. Its function is to transfer the heat produced by the combustion of fuel to water and ultimately to generate steam.

What should characteristics of What should characteristics of boiler?boiler?

Generate maximum steam. Light in weight and not occupy large space. Proper safety regulations. Cheaper in cost. Easily accessible for inspection and repair.

Sources of heat in boiler?Sources of heat in boiler?

Wood Coal Diesel Natural Gas Nuclear Energy

Types of Boiler?Types of Boiler?

1. Water Tube Boiler2. Fire Tube Boiler3. Packaged Boiler4. Stoker Fired Boiler5. Pulverized Fuel Boiler6. Waste Heat Boiler7. Fluidized Bed (FBC) Boiler

Water Tube BoilerWater Tube BoilerThe water is contained inside the tubes(called water tubes) which are surrounded by flames and hot gases from outside.•Used for high steam demand and pressure requirements •Capacity range of 4,500 – 120,000 kg/hourExamples: Babcock and Wilcox boilerStirling boilerLa - Mont boiler Yarrow boiler and Loeffler boiler

Water Tube BoilerWater Tube Boiler

• Used for high steam demand and pressure requirements

• Capacity range of 4,500 – 120,000 kg/hour

Fire Tube BoilerFire Tube Boiler In fire tube steam boilers, the flames and hot gases produced by the combustion of fuel pass through the tubes(called multi tubes) which are surrounded by water.

The heat is conducted through the walls of the tube from the hot gases through the surrounding water.

Fire Tube BoilerFire Tube Boiler Relatively small steam capacities (12,000 kg/hour). Operates with oil, gas or solid fuels.

Examples: •Cochran boiler, •Lancashire boiler, •Cornish boiler•Locomotive boiler•Taper boiler•Vertical fire tube boiler

Stoker Fired BoilerStoker Fired Boiler

A. Spreader stokers

• Coal is first burnt in suspension then in coal bed

• Flexibility to meet load fluctuations

• Favored in many industrial applications

• Uses both suspension and grate burning

Packaged BoilerPackaged Boiler

• Comes in complete package• Features

• High heat transfer• Faster evaporation • Good convective heat

transfer• Good combustion efficiency• High thermal efficiency

Oil Burner

To Chimney

Stoker Fired BoilerStoker Fired Boiler

B. Chain-grate or traveling-grate stoker

• Coal is burnt on moving steel grate• Coal gate controls coal feeding rate• Uniform coal size for complete combustion

Pulverized Fuel BoilerPulverized Fuel Boiler Generate thermal energy by burning pulverized coal

(powdered coal) or coal dust. Its an other name is Utility Boiler.

Coal is pulverized to a fine powder, so that less than 2% is +300 microns, and 70-75% is below 75 microns.

Pulverized coal powder blown with combustion air into boiler through burner nozzles.

Combustion temperature at 1300 -1700 °C

Pulverized Fuel BoilerPulverized Fuel Boiler

Benefits: varying coal quality coal, quick

response to load changes and high pre-heat air temperatures.

Waste Heat BoilerWaste Heat Boiler

Used when waste heat available at medium/high temp.

Auxiliary fuel burners used if steam demand is more than the waste heat can generate.

Used in heat recovery from exhaust gases from gas turbines and diesel engines.

Fluidized Bed (FBC) Fluidized Bed (FBC) BoilerBoiler• Particles (e.g. sand) are suspended in high

velocity air stream: bubbling fluidized bed• Combustion at 840° – 950° C Fuels: • coal, rice husk, bagasse and agricultural wastes

Benefits: • compactness,• fuel flexibility, • higher combustion efficiency

Fluidized Bed (FBC) Fluidized Bed (FBC) BoilerBoiler Fluidized Bed Boiler is categorized as:

• Atmospheric Fluidized Bed Combustion (AFBC) Boiler

• Atmospheric Circulating Fluidized Bed Combustion (CFBC) Boiler

Atmospheric Fluidized Bed Combustion (AFBC) Boiler

• Most common FBC boiler that uses preheated atmospheric air as fluidization and combustion air

Atmospheric Circulating Fluidized Bed Combustion (CFBC) Boiler

• Solids lifted from bed, rise, return to bed

• Steam generation in convection section

Benefits: • more economical, • better space utilization

and• efficient combustion

Conclusion:Conclusion:

Boilers are most important part of Chemical Industry. 99 % boilers used in Pakistan Chemical Industries are water tube boilers because of their high efficiency and safety. So we should have clear understanding about the boilers.