Power Plant Training Ppt 5a4b5n

INDUSTRIAL TRAINING at RELIANCE INFRASTRUCTURE EPC Division, Noida on Project: “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) b) c) d)

Acquisition & Processing of process data. Open loop and closed control. Calculation and optimization of the plant performance. 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

TYPICAL AUTO CONTROL LOOP Transmitters 4-20 mA

I/P Processing Module & selection scheme

Set Point Station

O

+

Feed back Indicator

Comparator

O Controller

. OOO

4-20 mA

A/M Station I/P Converter

F.B. Unit Control Valve

Typical Loop Schematic

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 SIGNALS The 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 single element control for low loads (< 30%) and by three element control for high loads (>30%). The change over of control regimes from single element control to three element control 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 variables measuring instruments (e.g. flow nozzle, thermocouple, DP transmitters), I/P card(s), process controllers, Human Machine Interface (HMI), O/P card(s) and requisite instruments.