ACTIVE LEARNING PROCESS

Prepared By :BINI MOL THOMAS 13BEECG069VISHAL SALVI 13BEECG067HARSHAL M.H 13BEECG064

Guided By : Prof. C O Yadav

Branch: Electronics & Communication

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Boilers

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1. Describe the theory, construction, and applications of boilers

2. Describe the common type of boilers

3. Explain how to assess the performance and efficiency of a boiler

4. Describe methods to improve boiler efficiency

5.List energy efficiency opportunities

Objectives

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Introduction – Purpose?

Type of boilers

Boiler Assessment

Energy efficiency opportunities

Objectives

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What is a Boiler?

Introduction

• Vessel that heats water to become hot water or steam

• At atmospheric pressure water volume increases 1,600 times

• Hot water or steam used to transfer heat to a process

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Introduction

BURNERWATER

SOURCE

BRINE

SOFTENERSCHEMICAL FEED

FUELBLOW DOWN SEPARATOR

VENT

VENTEXHAUST GASSTEAM TO PROCESS

STACK DEAERATOR

PUMPS

Figure: Schematic overview of a boiler room

BOILER

ECO-NOMI-ZER

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Types of Boilers

1. Fire Tube Boiler

2. Water Tube Boiler

3. Packaged Boiler

4. Fluidized Bed (FBC) Boiler

5. Stoker Fired Boiler

6. Pulverized Fuel Boiler

7. Waste Heat Boiler

What Type of Boilers Are There?

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Type of Boilers

(Light Rail Transit Association)

1. Fire Tube Boiler

• Relatively small steam capacities (12,000 kg/hour)

• Low to medium steam pressures (18 kg/cm2)

• Operates with oil, gas or solid fuels

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Type of Boilers

2. Water Tube Boiler

(Your Dictionary.com)

• Used for high steam demand and pressure requirements

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

• Combustion efficiency enhanced by induced draft provisions

• Lower tolerance for water quality and needs water treatment plant

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Type of Boilers

(BIB Cochran, 2003)

3. Packaged Boiler

Oil Burner

To Chimney

• Comes in complete package

• Features• High heat transfer• Faster evaporation • Good convective

heat transfer• Good combustion

efficiency• High thermal

efficiency

• Classified based on number of passes

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Type of Boilers

4. Fluidized Bed Combustion (FBC) Boiler• Particles (e.g. sand) are

suspended in high velocity air stream: bubbling fluidized bed

• Combustion at 840° – 950° C

• Fuels: coal, washery rejects, rice husk, bagasse and agricultural wastes

• Benefits: compactness, fuel flexibility, higher combustion efficiency, reduced SOx & NOx

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Type of Boilers

5. Stoke Fired Boilers

a) Spreader stokers• Coal is first burnt in suspension then in

coal bed

• Flexibility to meet load fluctuations

• Favored in many industrial applications

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Type of Boilers

5. Stoke Fired Boilers

b) Chain-grate or traveling-grate stoker

(University of Missouri, 2004)

• Coal is burnt on moving steel grate

• Coal gate controls coal feeding rate

• Uniform coal size for complete combustion

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Type of Boilers

Tangential firing

6. Pulverized Fuel Boiler

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

• Combustion temperature at 1300 -1700 °C

• Benefits: varying coal quality coal, quick response to load changes and high pre-heat air temperatures

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Independence Steam Electric Station - Newark, AR

Operation: Unit 1 - January 1983/Unit 2 - December 1984Fuel: Low-sulfur coal mined near Gillette, Wyoming Capability: 1,678 megawatts

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Type of Boilers

Agriculture and Agri-Food Canada, 2001

7. Waste 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

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Assessment of a Boiler

1. Boiler performance• Causes of poor boiler performance

- Poor combustion- Heat transfer surface fouling- Poor operation and maintenance- Deteriorating fuel and water quality

• Heat balance: identify heat losses

• Boiler efficiency: determine deviation from best efficiency

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Assessment of a Boiler

Heat BalanceAn energy flow diagram describes geographically how energy is transformed from fuel into useful energy, heat and losses

StochiometricExcess AirUn burnt

FUEL INPUT STEAM OUTPUT

Stack Gas

Ash and Un-burnt parts of Fuel in Ash

Blow Down

Convection & Radiation

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Assessment of a Boiler

Heat BalanceBalancing total energy entering a boiler against the energy that leaves the boiler in different forms

Heat in Steam

BOILER

Heat loss due to dry flue gas

Heat loss due to steam in fuel gas

Heat loss due to moisture in fuel

Heat loss due to unburnts in residue

Heat loss due to moisture in air

Heat loss due to radiation & other unaccounted loss

12.7 %

8.1 %

1.7 %

0.3 %

2.4 %

1.0 %

73.8 %

100.0 %

Fuel

73.8 %

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Assessment of a Boiler

Heat BalanceGoal: improve energy efficiency by reducing avoidable lossesAvoidable losses include:

- Stack gas losses (excess air, stack gas temperature)

- Losses by unburnt fuel

- Blow down losses

- Condensate losses

- Convection and radiation

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Assessment of a Boiler

1. Boiler EfficiencyThermal efficiency: % of (heat) energy input that is effectively useful in the generated steam

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THANK YOU....