28-12-2012, 01:41 PM
BOILER
1BOILER.docx (Size: 1.26 MB / Downloads: 35)
Introduction:
• A boiler is used to generate steam at a desired pressure and temperature by transferring heat produced by burning fuel to water to change it to steam.
In RPSCL, steam is generated at a pressure of 167 bar and temperature of 540⁰C.
Principle of combustion:
• The mere fact that oxygen is brought into the presence of a combustion substance does not mean that combustion will automatically follow :
Fuel & Air require :
Temperature – ignition temperature must be reached before combustion can start.
Turbulence - necessary during mixing for air & fuel to be intimately mixed.
Time – time is required for complete burning to occur
• In a boiler, ignition is provided as the fuel and air are brought together so that there is a progressive burning of fuel and a flow of combustion products to the chimney. The mixing of air & fuel is carried out by the burner.
• Furnace Explosions result from the ignition of unburnt fuel and oxygen after they have accumulated in the boiler, and not in the burner itself as could be expected. Before the accumulation can explode, air & fuel must be present in certain ratios. When the ratio of the explosion has been reached an ignition source is necessary, e.g. hot metal, hot refractory, hot gases, stray zones of combustion.
Boiler Operations
The boiler operator is responsible for operating and maintaining the boiler in a safe and efficient manner through the use of sound engineering.
Most boiler accidents are caused by operator error and poor maintenance.
The boiler operation consist of:
FD fans
ID fans
PA fans
Dearators
Safety valves
Water level gauges
Air-preheater
Economizer
Super heater
Boiler Feed pump
Pressure reducing valve