🔥 Steam Generation in a Boiler

Boilers are the heart of many industries — from power plants to chemical factories. They convert the chemical energy of fuel into heat energy, which is then used to produce steam from feedwater. Steam is vital for power generation, heating, and industrial processes.

This Blog explains steam generation in a boiler step by step, using simple language for easy understanding.

Step-by-step Steam Generation Process.

1. Fuel Combustion in the Furnace

Fuel (coal, oil, gas, or biomass) is burned in the furnace.
The furnace design depends on the type of fuel used.
Burning fuel releases heat energy, which is transferred to water tubes.

2. Water Walls and Tube Circulation

Water tubes arranged around the furnace are called water walls.
Cold feedwater enters from the boiler drum into these tubes.
As tubes absorb heat, water circulates naturally due to density difference:

Circulation Force F = Rho Cw* H1 - Rho Hw* H2

Where:

(Rho Cw) = density of cold water
(Rho Hw) = density of hot water
H1 and H2 are the heights of water and steam respectively.
In some boilers, forced circulation pumps are used to improve flow.

3. Steam Formation in the Drum

Heated water returns to the steam drum.
Steam separates from water and collects at the top of the drum.
This is saturated steam, corresponding to drum pressure.
Steam is further heated in superheaters to produce superheated steam for turbines.

4. Economiser – Preheating Feedwater

Before entering the drum, feedwater passes through an economiser.
Economiser uses leftover heat from flue gases to preheat water.
This improves efficiency and reduces fuel consumption.

5. Air Heater – Preheating Combustion Air

Combustion requires oxygen from air.
Forced Draught (FD) fans supply air to the furnace.
Air is preheated in an air heater using hot flue gases.
Preheated air ensures better fuel burning and energy savings.

6. Flue Gas Cleaning and Exhaust

After transferring heat, flue gases pass through an Electrostatic Precipitator (ESP).
ESP removes dust particles before gases exit through the chimney.
Clean fuels like oil and gas may not require ESP.

7. Fuel and Ash Handling

Fuel is stored in a fuel storage yard and fed to the boiler as needed.
Ash from solid fuel combustion is collected at the bottom and ESP.
Ash is disposed of using an ash handling system.

📊 Boiler Components Involved in Steam Generation

Furnace: Burns fuel to release heat.
Water Walls: Tubes around furnace absorbing heat.
Steam Drum: Collects steam and water.
Economiser: Preheats feedwater using flue gas.
Air Heater: Preheats combustion air.
ESP & Chimney: Cleans and exhausts flue gas.
Fuel & Ash Handling Systems: Manage input and output of solid fuels.

🌍 Types of Boilers

Water Tube Boilers: Water flows inside tubes, heated by flue gas outside.
Fire Tube Boilers: Flue gas flows inside tubes, water surrounds them.
Waste Heat Recovery Boilers: Use waste heat instead of fuel combustion.

Boiler Basics

Pages

1/01/2026

Explain Steam Generation in a Boiler