24-09-2012, 04:02 PM
Modelling and Analysis of SGLC System
Modelling and Analysis.pptx (Size: 884.04 KB / Downloads: 28)
STEAM GENERATOR (SG)
Used to transfer the heat from the reactor cooling system to the secondary side of the tubes which contain feed water.
There are three types of steam generators : Vertical U-tube,Horizontal,Once through
In Taps 3,4 we use a vertical, mushroom shaped, recirculation type heat exchanger, with inverted U tubes for primary flow.
Steam Separator
to remove the water from the steam. This is done to ensure that the steam impinging on the turbine blades causes minimal erosion.
There are 23 separators in each SG in TAPS 3-4.
Separators in the SG work on the centrifugal principle
Steam coming out of the separator is 98% dry whereas the steam coming out of the drier is 99.75% dry.
Importance of SG level control
Poor control of the nuclear steam generator (SG) water level of pressurized Water Reactor can lead to frequent reactor shutdowns.
Conventional feed-water control schemes cannot provide satisfactory performance within the required wide operating range of 0 to 100% of the specified load.
A review of past PWR plant operation experiences indicates that unplanned reactor trips due to SG level control have been significant contributors to plant unavailability.
OBJECTIVE
The functions of the SGLC system are to:
Maintain required level of feed water so that continuous removal of heat from the reactor is ensured at all stages of the program.
Ensure the proper removal of decay heat during reactor setback/trip signals at very low levels of SG water.
Protect the turbine from moisture carry over by steam by ensuring turbine trip at very high level.
SG LEVEL MEASUREMENTS
SG level is measured by inferential, wet leg type method due to pressurised and containing vapours/fluids.
Each SG level is measured by 10 different pressure type level transmitters.
Out of these 3 are Narrow range (NR) level transmitters, 3 are Wide range (WR) level transmitters and 3 are Mid range (MR) transmitters.
1 transmitter is used for calculating density correction factor