power plant training ppt
TRANSCRIPT
INDUSTRIAL TRAININGat
RELIANCE INFRASTRUCTUREEPC Division, Noida
onProject: “Design Of Feed Water
Control System” in Thermal Power Plant
Familiarization with Typical Thermal Power Plant
Feed Water & Steam Flow Diagram
Control & Instrumentation System in power plant
1.Furnace Safeguard and Supervisory System(FSSS).
2.Automatic Turbine Run-up System(ATRS).
3.Turbine Digital Electric Hydraulic control system(DEH) .
4.Distributed Control System(DCS).
a) Acquisition & Processing of process data.
b) Open loop and closed control.
c) Calculation and optimization of the plant performance.
d) Monitoring, signaling, operation and visualization of the process.
Feed Water Control
Feed Water Drum Level
Control
Single Element Drum Level
Control
Two Element Drum Level
Control
Three Element Drum Level
Control
Enhance Three Element Drum Level Control
DP Across Feed Regulating Valve
Control
I/P Processing Module &
selection scheme
Comparator
Controller
4-20 mA
I/P Converter
Set Point
Station
F.B. Unit
Transmitters
4-20 mA
O O O
Feed back
Indicator
A/M Station
.
Control Valve
Typical Loop Schematic
O O
TYPICAL AUTO CONTROL LOOP
+ -
Control strategy for feed water flow
Single element control Two element control Three element control
The parameters used in the control system, which are measured, are: -
a) Drum Level
b) Drum Pressure
c) Steam Flow
d) Feed Water Flow
Instruments required for measurement are: -
1. Electronic Transmitter for measuring :-
i. DP across flow nozzle for feed water flow
ii. DP across flow nozzle for steam flow
iii. DP for Drum Level
2. Temperature elements (Thermocouples) for
i. Feed Water Temperature
ii. Steam Temperature
3. Flow Nozzle for
i. FW Flow
ii. Steam Flow
INPUT AND OUTPUT SIGNALSThe inputs for the feed water control system are: -
• Feed water flow signal from DP Transmitter (4-20mA) - 1 no.
• Steam flow signal from DP Transmitter (4-20mA) - 1 no.
• Drum level signal from DP transmitters (4-20mA) - 1 no.
• Drum pressure signal from pressure transmitter (4-20mA) -1 no.
• Feed water temperature signal from thermocouple - 1 no.
• Steam temperature signal (4-20mA) - 1 no.
• Steam pressure signal (4-20mA) - 1 no.
The outputs of the Feed Water Control System are: -
• 4-20 mA output electrical signals for controlling the speed of BFP - 1no.
• 4-20 mA output (Single Element Controller ) for Low Load Feed Control
Valve – 1 no.
HARDWARE REQUIRED FOR FEED WATER CONTROL SYSTEM :-
• Controller for implementing the controls-1 no.• 4-20mA input cards for 6 signals• Thermocouple input cards for 2 signals• 4-20mA output cards for 2 signals.
Typical Architecture Of Control Strategy
Feed Water and Steam Flow Control Elements
CONCLUSION
Feed water level in boiler drum is controlled by singleelement control for low loads (< 30%) and by three elementcontrol for high loads (>30%). The change over of controlregimes from single element control to three elementcontrol is carried out automatically whenever the load(Steam Flow) exceeds 30% of Maximum Continuous Rating(MCR) and vice versa.
For the control process we use process variablesmeasuring instruments (e.g. flow nozzle, thermocouple, DPtransmitters), I/P card(s), process controllers, HumanMachine Interface (HMI), O/P card(s) and requisiteinstruments.