10-04-2012, 01:28 PM
Boilers & Thermic Fluid Heaters
Boilers & Thermic Fluid Heaters.ppt (Size: 2.35 MB / Downloads: 115)
Introduction
What is a Boiler?
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
Types of Boilers
What Type of Boilers Are There?
Fire Tube Boiler
Water Tube Boiler
Packaged Boiler
Fluidized Bed (FBC) Boiler
Stoker Fired Boiler
Pulverized Fuel Boiler
Waste Heat Boiler
Thermic Fluid Heater (not a boiler!)
Type of Boilers
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
2. Water Tube Boiler
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
3. Packaged Boiler
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
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
Capacity range 0,5 T/hr to 100 T/hr
Fuels: coal, washery rejects, rice husk, bagasse and agricultural wastes
Benefits: compactness, fuel flexibility, higher combustion efficiency, reduced SOx & NOx
4a. Atmospheric Fluidized Bed Combustion (AFBC) Boiler
Most common FBC boiler that uses preheated atmospheric air as fluidization and combustion air
4b. Pressurized Fluidized Bed Combustion (PFBC) Boiler
Compressor supplies the forced draft and combustor is a pressure vessel
Used for cogeneration or combined cycle power generation
4c. 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