๐Ÿ”ฅ 1. What is an EGB Boiler (Exhaust Gas Boiler)?
An EGB boiler โ€” also known as a Waste Heat Recovery Boiler โ€” is a heat exchanger that recovers heat energy from the exhaust gases of engines or generators.
Instead of letting hot exhaust go to the atmosphere, the EGB uses that heat to produce hot water or steam.
โš™๏ธ 2. Working Principle
Process Flow:
Exhaust Source: Hot flue gas from the generator or engine exhaust enters the EGB boiler inlet.
Heat Transfer: The gases pass through tubes surrounded by water inside the boiler shell.
Heat Absorption: Heat from the gas transfers through the tube walls, heating the water.
Steam or Hot Water Output: The heated water is either:
turns into steam for use in a process or heating system, or
becomes hot water stored in a tank or used directly.
Cooled Exhaust Outlet: The now-cooler exhaust gases leave the EGB through the outlet stack.
๐Ÿงฎ 3. Example Calculation (Simplified)
If a 1 MW gas generator produces exhaust gas at 450ยฐC and a flow of 5,000 kg/hr,
And if you cool it down to 180ยฐC, the recoverable heat is:
Q = 5000 ร— 1.0 ร— (450 - 180) = 1,350,000 kcal/hr โ‰ˆ 1.57 MW ๎€
If the boiler efficiency is 70%, you can recover about 1.1 MW of heat,
enough to produce roughly 1,700 kg/hr of steam at 7 bar.
๐Ÿ’ฐ 4. Profit / Benefits
Aspect
Advantage
Fuel Saving
Reduces fuel use for auxiliary boilers โ€” the waste heat is free energy.
Lower Operating Cost
Reduces diesel/gas consumption and maintenance.
Environmental
Cuts COโ‚‚ emissions by recovering waste heat.
Efficiency
Increases total plant efficiency from 35โ€“40% to up to 70%.
Reliability
Provides continuous hot water/steam when the generator is running.
Payback Period
Typically 1โ€“2 years, depending on usage and fuel cost.
๐Ÿงฐ 5. Mechanical Drawing (Simplified Schematic)
Hereโ€™s a simple layout of how an EGB boiler connects to a generator exhaust system:
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โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
     โ”‚       GAS GENERATOR          โ”‚
     โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ฌโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜
             โ”‚  Exhaust Gas (450ยฐC)
             โ–ผ
     โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”
     โ”‚      EXHAUST GAS BOILER      โ”‚
     โ”‚  (Water inside shell)        โ”‚
     โ”‚  โ”Œโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”  โ”‚
     โ”‚  โ”‚   Tube Bundle          โ”‚  โ”‚
     โ”‚  โ”‚ (Gas inside tubes)     โ”‚  โ”‚
     โ”‚  โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜  โ”‚
     โ”‚      โ†‘ Water in/out        โ”‚
     โ””โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”ฌโ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”€โ”˜
             โ”‚
             โ–ผ
      Hot Water or Steam Outlet
             โ”‚
             โ–ผ
      Process Use / Storage Tank

     Exhaust Out (โ‰ˆ180ยฐC)
             โ–ฒ
             โ”‚
          Chimney
๐Ÿงฉ 6. Key Components
Exhaust Gas Inlet/Outlet
Tube Bundle (Heat Transfer Tubes)
Water Drum / Steam Drum
Safety Valve & Pressure Gauge
Bypass Damper (Optional)
Economizer (Optional โ€“ extra stage)