Practical Boiler Control and Instrumentation for Engineers and Technicians
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Transcript of Practical Boiler Control and Instrumentation for Engineers and Technicians
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Practical Boiler Control and Instrumentation for
Engineers and Technicians
Technology Training that Workswww.idc-online.com/slideshare
Performance objectives of Boiler Controls
Safety
Safety trip systems
Availability Performance
Burner safety
Regulatory
Reliable C & I
Secure software
Robust controls
Trouble shooting
Stable controls
Dynamic response
Operability
Efficiency
Testing Maintenance
Objectives of Boiler ControlsObjectives of Boiler Controls
Know the hazards
Figure 1.1 Key objectives and performance indicators for boiler control systems
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Elementary block diagram of boiler processes
Fuel in / Steam out!
Heating , Evaporation &
Superheating
Feed water Steam
Blow Down
Heat Transfer
Fuel
Air
Hot Gas
Ash removal
Mixing and heating
Radiant heat
Combustion furnace
Flue GasSteam/Water system
Combustion system
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Boiler process model expansion
Feed Water
DrumSat. Steam
S/H 1
Steam toUsers
Economiser
Atmosphere
Air HeaterWind box
Combustion in furnace
Water Circulation
WarmAir
Heat to Superheaters
Flue Gas Heat
F D Fan
I D Fan
Burners
Fuel feeders
S/H 2
Heat to evaporation
De-S/H
Figure 1.3 Expanded model for the boiler process
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Heat conversion in the boiler
Heat to raise water to boiling temperature
Heat to evaporation to convert to steam
Heat to superheat the steam
Heat from combustion of fuel
Heat to atmosphere
Temperature
Heat content
Output superheated steam: intensive energy supply
Feedwater
Heat recovery to incoming air and water
Figure 1.4Heat input requirements for steam generation at atmospheric pressure
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Interaction of variables in the boiler processes
Interaction of variables in the boiler processes
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Typical Horizontal Return Tube Fire-Tube Boiler
Figure 1.6 Early type of firetube boiler
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Typical 3 or 4 pass Horizontal (Scotch Marine) Fire Tube Boiler
Figure 1.7 Example of the firetube boiler
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Fundamentals of the water tube boiler circulation and its superheater
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Section through typical industrial boiler
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Atmospheric fluidized bed boiler
Figure 1.10Example of a fluidized bed boiler with gravimetric feeder for coal or waste material
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Boiler (Drum) level control function
Drum (Water inventory)
Feedwater supply rate
Steam flow
Level control
LT
PV(Process Variable)
MV ( Manipulated Variable)
Set Point
-+
+-
Ref section 1.6 of manualBoiler Control Functions
Figure 1.11Basic control function for drum level
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Furnace ID Fan extraction rate
Draft control
PT
PVMV
SP
+-
-+
Furnace pressure control function
FD air flow
Difference will integrate to change pressure over time
What determines this set point?Ref section 1.6 of manual
Boiler Control Functions
Figure 1.12Basic control function for furnace draft
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Outline of the combustion control function
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Outline of the pressure and load control functionRef section 1.6 of manualBoiler Control Functions
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De-superheater spray flow valve
TT
PV
MV
SP
+-
-
Steam temperature control function
Temperature control
Water flow to de-superhtr.
Heat flow to 1st stage
+Steam temp from 1st stage superhtr.
Heat flow to 2nd stage
2nd stage superheater.
Ref section 1.6 of manualBoiler Control Functions
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