ORNL-2106 - the Molten Salt Energy Technologies Web Site

ANP PROJECT PROGRESS REPORT
and in NaK systems at high temperatures. This
type of flowmeter does not require penetrations to
the process fluid, and it gives very accurate flow-
rate data.
The flow-sensing unit, shown in Fig. 1.3.2,
consists of an Inconel turbine, or rotor, supported
by ti tan ium carbide bearings, and flow-straightening
vanes of Inconel, which, in turn, support the turbine
bearings. The fluid enters the vanes and then
impinges on the turbine blades and causes the
turbine to rotate. The turbine contains, within its
body, a small cabalt vane, which has the unique
property of retaining its magnetic characteristics at
temperatures up to 2100OF. A permanent magnet
assembly is used outside the piping to establish a
uniform magnetic field perpendicular to the axis
of rotation of the turbine and the cobalt vane con-
tained therein. A pickup coil, with a large number
of turns, is mounted so that it intercepts the
magnetic lines of flux of the magnet. When the
TITANIUM CARBIDE SHAFTS
turbine is rotated by the fluid, the cobalt vane
rotates and cuts the lines of flux of the magnet;
this changing flux generates a voltage in the pickup
coil. Thus, the number of pulses per unit time is
a direct measure of the turbine speed, which, in
turn, is a linear measure of the flow rate. The
speed of the turbine (in counts, or pulses, per
second) can be measured quite readily by using
appropriate standard electronic equipment, such as
a linear rate meter or scaler. Since the turbine
speed is a linear function of the flow, the flow rate
(in gpm) can be plotted against counts (pulses) per
second. This device is not dependent upon pres-
sure, temperature, or specific gravity but is de-
pendent upon viscosity. The viscosity effect,
which causes turbine "drag," is not appreciable,
however, at viscosities below 5 cp. A water-
calibration curve of turbine speed vs flow rate is
presented in Fig. 1.3.3. Calibration of this type
of flowmeter with water is valid for the fused-salt
fuel mixtures.
-FLOW DIRECTION
RETAINER RING
UNCLASSIFIED
PUOTO 26t44
LINLET SIDE GUIDE AND BEARING ASSEMBLY
Fig. 1.3.2. ORNL-Designed Turbine-Type Flowmeter for Flow Measurements in the Range 25 to
50 gpm at Temperatures Up to 1600'F.
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