IGCAR : Annual Report - Indira Gandhi Centre for Atomic Research

IGC
Annual Report 2007
investigated in these studies.
The need for devices to mitigate
entrainment was established
form these studies.
Efforts to finalize an optimum
configuration of the device that
would serve to eliminate
entrainment was carried
forward through a series of flow
visualization tests in the model
using water as the simulant.
The selection of the devices
employed for testing was,
governed by the philosophy to
reduce the height of the liquid
column above the outlet nozzle
for the onset of entrainment.
Pepper pot
Fig.1 Pepper pot assembly in model
Fig.2 Ring plate cylindrical
perforated shell
Fig.3 Minimum height required to avoid gas entrainment for different conditions
The efficacy of devices was this device was used in
proven with simple stiffener combination with a Ring
rings and porous plates, plate Cylindrical Perforated
wherein the height of liquid
column at which initiation of
Shell (RCPS) (Fig. 2). This
combination was found to be
entrainment occurs had very effective and the minimum
dropped considerably possible height of liquid
compared to the case without column without entrainment for
any device. However the nominal flow was 1320 mm
reference height of the liquid from the outlet nozzle
column based on the corresponding to 2050 mm in
operational requirements was prototype. The tests have
even lower. It was necessary to
test a combination of devices
confirmed the adequacy of the
configuration and the same is
like the stiffener ring in recommended for deployment
conjunction with porous plates in the reactor.
to reduce this liquid column
height. A series of test with 22
Fig. 3. shows the minimum
height required to avoid gas
different configurations were entrainment for different
conducted to reduce this combinations in model. The
height. The pepper pot effect of devices is not
configuration (Fig.1) was one considerable at low Froude No.
device which, when tested (upto 2.5) whereas for higher
produced very encouraging
results But to reduce the liquid
column height further to the
required levels the variations in
the geometry of the pepper pot
Froude No. the configuration
of devices plays an important
role in minimizing the gas
entrainment phenomenon at
lower heights of liquid column.
alone was not sufficient. Hence,
74 R&D FOR FBRs