Boiler - Elearn.micet.unikl.edu.my
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BOILER
Presented by:
Muhammad Azffar
Mohamad Hanif bin Yusof
Nor Aminah bt. Mohd Khalil
55201112096
55201112125
55201112073
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
Introduction
STEAM TO
PROCESS
VENT
EXHAUST GAS
STACK
DEAERATOR
PUMPS
ECONOMI-ZER
VENT
BOILER
BURNER
BLOW DOWN
SEPARATOR
WATER SOURCE
FUEL
BRINE
CHEMICAL FEED
SOFTENERS
Figure: Schematic overview of a boiler room
3
Type of boiler:
Fire tube boiler
Water Tube Boiler
Packaged Boiler
Fluidized Bed (FBC) Boiler
Stoker Fired Boiler
Pulverized Fuel Boiler
Fire Tube Boiler
•Hot gases from a fire
pass through one or more
tubes running through a
sealed container of water
•Relatively small steam
capacities (12,000
kg/hour)
•Operates with oil, gas or
solid fuels
Water Tube Boiler
• Used for high steam
demand and pressure
requirements.
•
Forced, induced and
balanced draft provisions
help to improve combustion
efficiency
• Less tolerance for water
quality calls for water
treatment plant.
Packaged Boiler
•require less fuel and
electric power to operate
•High thermal efficiency
•High heat transfer
•Faster evaporation
•Reduces operating cost
Fluidized Bed Combustion Boiler (FBC)
• Particles (e.g. sand) are
suspended in high velocity air
stream: bubbling fluidized bed
• Bed is where the coal or fuel
spreads
• Fuels: coal, washery rejects,
rice husk, bagasse and
agricultural wastes
• Benefits: compactness, fuel
flexibility, higher combustion
efficiency
Stoker Fired Boiler
•the smallest units among hard
coal fired boilers
•Coal is fed onto one end of a
moving steel grate
•A coal gate is used to control the
rate at which coal is fed into the
furnace by controlling the
thickness of the fuel bed
•Uniform coal size for complete
combustion
PULVERIZED FUEL BOILER
is an utility boiler that generates
thermal energy by burning
pulverized coal
Pulverized coal powder blown
with combustion air into boiler
through burner nozzles
Benefits: varying coal quality
coal, quick response to load
changes and high pre-heat air
temperatures
MAINTENANCE OF
BOILER OPERATION
ANNUAL MAINTENANCE & SHUTDOWN
Maintenance & shutdown usually done once in a year
Depends on when company want to do the shut down
Maintenance needed to ensure the boiler works efficiently
During shutdown or maintenance steam is not available for heating/ domestic
hot water
BOILER WATER TREATMENT
Primary goal is to control solid cause deposit in boiler & control gas that cause
corrosion
3 phases of water treatment in boiler system :
Blowdown
External treatment
Internal treatment
BLOWDOWN
Classified into surface and bottom blowdown
Surface blowdown is removed from the steam
drum at the top of the boiler
Bottom blowdown is removed from the mud
drum at the bottom of the boiler
Maintains the total dissolved solid in the system
EXTERNAL TREATMENT
Major techniques employed for external treatment:
Clarification process
Filtration process
Softening action
De-alkalization action
De-mineralization technique
Removes hard salts, minerals and oxygen before the water enters the boiler
In some cases the treatment done outside the boiler system
INTERNAL TREATMENT
Continue from external treatment to avoid catastrophic failure or any other
unfavourable effect
Maintains proper water chemistry by adding chemical additives to the boiler
water
Usage of natural & synthetic dispersant (lignosulphonates/maleic acrylate copolymer)
Softening chemicals (soda ash & sodium phosphate)
Eliminate oxides and dissolved oxygen present (ascorbic acid & hydrazine)
T YPE OF MAINTENANCE OPERATION
EQUIPMENTS
Normal Operating Water Level
Maintaining normal operating water level
Low water level is most common cause boiler failure
How to Prevent
Automatic boiler feed water regulator is designed to
maintain the proper water level in the boiler
The gage glass (sight glass) is a tube that indicates the
water level in the boiler.
The Fuel System
Failure to maintain the equipment in good working
order could result in higher fuel costs, the loss of heat
transfer or even a furnace explosion.