BOILER CONTROLS
Operational Philosophy,
Control Logics & Instruments
AT HOTEL SURYA PALACE, VADODARA
Hemendra Dholakia & Ansuman Sen Sharma
What is our
objective?
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Objective
Significance of various process
parameters in Boiler
Objectives of the principal boiler
control functions
Principles and design concepts of
important controls
Basics of Instruments used for
measuring process parameters
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Objective
Setting up and tuning of boiler control
loops
Safety control and start-up interlock
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Steam Generating System
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Steam Generator
The steam generator is a plant for energy
conversion and transfer
Conversion of Heat Energy from Chemical
energy of fuel
Transfer of Heat energy into water &
Steam
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Steam Generating System
PF Boiler
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GEN
IP LP
HP
Attemperator ID Fan
ESP
Economizer FD Fan & PA Fan
APH
Turbine Extraction
RH
SH-1 SH-2
Deaerator
LP Heater
Down comer
Riser
Riser
HP Heater
Boiler Feed Pump
FROM FUEL HANDLING Cond. Extraction Pump
SYSTEM
From Turbine
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Feed Water System:
Boiler Circulating Water & Steam System :
Fuel System :
Combustion Air System :
Flue Gas System :
Steam System :
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You cannot Manage what you
cannot Measure
(Accurately)
- Jack Welch, CEO, General Electric
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Parameters Measured:
Pressure
Temperature
Flow
Level
Gas composition
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Boiler Feed Water System:
PT
PT LT TE
LT
Economizer
SH-1 SH-2
TE
TE
TE Deaerator
LP Heater
Down comer
Riser
Riser
HP Heater
FT
PT
TE
TE
Boiler Feed Pump
Cond. Extraction Pump
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Air and Gas System
TE TE
AT
PT FT
ID Fan
ESP
FD Fan
APH
TE PT
PT
TE
PT 14
Three Questions:
How do we Measure?
Why do we measure?
How the control works?
Lets start by understanding the
fundamental of measurement with help of
Instrumentation
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P&ID
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Piping & Instrumentation Diagram
The P&ID is an important document establishing the
blueprint for every process.
P&ID drawings outline
the plants operation,
identify/describe the role of equipment,
show all the interconnecting pipe lines.
The instrumentation part provide the main
schematic of how plant processes are controlled to
facilitate a smooth and safe operation.
Symbolic presentation of the various equipment,
devices and control concepts that go into our plants.
Schematic presentation of functional relation of
piping, instrumentation and system equipment
components
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Piping & Instrumentation Diagram
understanding of P&ID interpretation is
important to virtually every discipline
involved in a process plant from process
engineering and detail design through
construction, commissioning/start-up,
operations and management.
P & ID talks through symbols, about
What is that device?
Where is it located?
Why is it there? ( especially
instrumentation)
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Piping & Instrumentation Diagram
A P&ID should typically include:
Instrumentation and designations
Mechanical equipment with names and numbers
All valves and their identifications
Process piping, sizes and identification
Miscellaneous - vents, drains, special fittings, sampling
lines, reducers and increasers etc.
Permanent start-up and flush lines
Flow directions
Interconnections references
Control inputs and outputs, interlocks
Annunciation inputs
Computer control system input
Vendor and contractor interfaces
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Piping & Instrumentation Diagram
Identification of components and subsystems
delivered by others
Intended physical sequence of the equipment
Equipment rating or capacity
Typical Exclusions are :
Instrument root valves
control relays
manual switches
primary instrument tubing and valves
pressure temperature and flow data
elbow, tees and similar standard fittings
extensive explanatory notes
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P& I Diagram Mechanical Equipment
Symbols
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P&I Diagram Process valve symbols
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P&I Diagram Line symbols
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P&I Diagram Line Connection symbols
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P&I Diagram Instrumentation symbols
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P&I Diagram Instrumentation symbols
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P&I Diagram Instrumentation symbols
Valve Actuator Types
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P&I Diagram Instrumentation symbols
Valve Failure Modes
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P&I Diagram Instrumentation symbols
Flow Measurement Devices Flow left to right
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P&I Diagram Instrumentation Tagging
The letters on the first line are in accordance with
ISA standard 5.1
legend
P&I Diagram Instrumentation Tagging
P First Letter stands for Pressure
D Second letter is a modifier for the first and
stands for Differential
I Third letter stands for Indicating
T Fourth letter stands for Transmitter
1703 is the loop number
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P&I Diagram Instrumentation Tagging
The ISA S5.1
recommended
tagging system
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Symbols in Piping & Instrumentation
Diagram
For every P&ID set there are Legend Sheets
Legend sheets also called lead sheets narrate
symbols used
Study of P&ID in conjunction with Legend
sheets develop understanding of the Plant
Example-PIDs-and-Lead-Sheets
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SUMMARY : P&I DIAGRAMS
Schematic presentation of functional relation of
piping, instrumentation and system equipment
components
For every discipline involved in a process plant from
process engineering and detail design through
construction, commissioning/start-up, operations and
management.
P & ID talks about
What is that device?
Where is it located?
Why is it there?
Standardized SYMBOLS form the language of the
diagram.
Legend Sheets or Lead Sheets explain symbols used
that develop understanding of the plant
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LOOP DIAGRAM AS PER SAMA STANDARD
Scientific Apparatus Makers Association (SAMA)
Functional control diagrams for the power industry are
often referred to as SAMA diagrams.
Symbols categorized as
Enclosure symbols
Signal continuation symbols
Signal processing symbols
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SAMA Enclosure Symbols
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SAMA Signal Continuation Symbols
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SAMA Signal Processing Symbols
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SAMA Loop Diagram
Measuring Device
(Transmitter) Continuously variable
signal
Proportional + Integral
Manually varied Automatic controller
set point
Auto/Manual transfer
Manually operated
Variable signal Generator Output Generator in
Manual Mode
Final Control Element
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ISA v/s SAMA Diagram
Transmitter
Controller
Auto/ Manual signal
selection/ operation
Final
Control
Element
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