PNNL-13501 - Pacific Northwest National Laboratory

Approach
Two flow loops, one that operates in the laminar flow
regime, and one that operates over a higher flow rate
range, were developed to provide a flexible system for
sensor evaluation. The laminar flow loop, shown in
Figure 1 was designed especially for evaluating
applications for ultrasonic doppler velocimetry and
pressure drop, a technique to provide rheological profiles
across the pipe. Based on conservation of linear
momentum for steady pressure-driven flow, the pressure
drop in the pipe provides the local shear rate distribution.
Figure 1. Laminar flow loop instrumented with an
ultrasonic doppler velocimetry sensing system for in-line
velocity and viscosity profile measurements
Evaluating the shear rate and the shear stress at points
along the pipe yields the shear stress shear rate relation,
which is equivalent to the shear viscosity shear rate
relationship. This information and attenuation profiles
can provide both rheological and concentration profiles of
the fluid flowing in the 5-cm- (2-in.-) diameter loop. A
Moyno pump provides flow rates of up to 40 L/min. The
flow rate range and piping configuration were designed to
provide fully developed laminar pipe flow and pressure
drop measurements (the theory and operation of the
sensing system are described in Powell et al. [2000]).
Laminar flow loop support instrumentation includes
measurement of temperature, flow rate, and pressure drop.
The second loop, shown in Figure 2, is powered by a
centrifugal pump that provides a flow rate from 114 to
568 L/min (30 to 150 gal/min). This flexible
configuration includes two pipelines, a 2.5-cm- (1-in.-)
diameter and 5-cm- (2-in.-) diameter. These lines can be
operated either singly or in parallel. The lines include
penetrations to permit integration of spool pieces housing
several existing ultrasonic sensors, shown in Figure 3.
These ultrasonic densimeters measure the density at the
sensor-fluid interface based on the amount of reflected
ultrasonic signal (Greenwood et al. 1999). In addition to
density, by making measurements at multiple orientations,
the sensors can be used to characterize sedimentation, the
presence of bubble layers, and detect density gradients.
Figure 2. Variable-flow rate, low-volume flow loop for
slurry process evaluation using multiple ultrasonic sensing
systems
Figure 3. a) Prototype ultrasonic densimeter spool piece,
b) Ultrasonic densimeter spool piece for deployment at
Hanford to support radioactive waste transfers
Instrumentation in each line to support loop operation
includes temperature measurement; Micromotion coriolus
mass flow meters to measure mass flow rate, density, and
temperature; and Controlotron clamp on ultrasonic flow
meters to measure volumetric flow and velocity. The
process sensors are integrated into a data acquisition
computer.
In addition to fluid evaluation during pipeline transport,
sensors such as the immersion densimeter (shown in
Figure 4a) and the concentration and particle sizing sensor
(shown in Figure 4b) can be installed into the fluid
a
b
Separations and Conversions 425