Transcript Boiler - Elearn.micet.unikl.edu.my

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.