A pdf version of this page can be found on the
is a non-intrusive multiphase flow analysis system based
on electrical capacitance tomography (ECT). With a Tomoflow
R100 package including Flowan* software
- Image flows of fluid/fluid and fluid/solid mixtures,
- Measure the velocity at any point or over any zone
in the flow-field,
- Investigate the details of flow structures,
- Measure the flowrate of a dispersed phase as a function
of time and space,
- Measure the volume of moving structures within the
The Tomoflow R100 multiphase flow
analysis system consists of a capacitance measurement
unit, real-time data acquisition and image reconstruction
software, and off-line multiphase flow analysis software.
Data Acquisition - DAM200e
DAM200e is an electrical
capacitance tomography measurement unit made for
Tomoflow by Process Tomography Ltd***.
DAM200e allows measurements on two axially separated
planes with up to 12 electrodes on each, with
drive for up to 12 sets of guard electrodes. Image
capture rates can be set by the user up to the
approximate maximum rates given below.
- Number of sensor electrodes 6, 8 or 12
- 200 frames per second with 8 electrode twin-plane
- 100 frames per second with 12 electrode twin-plane
Image capture and reconstruction software
ECT32 is a comprehensive
on-line software suite for controlling and processing
data from Tomoflow and PTL ECT systems. The software
runs on the Windows operating systems. The images
can be shown on the screen in real-time, then
recorded and played back at user-defined speeds.
Data files can be used for flow analysis using
The IU2000 Image Utility software is an extensive
set of off-line tools for processing and viewing
captured ECT image data.
Matect software is a set of off-line Matlab utilities
for displaying and modifying sensitivity maps
and for generating images using these maps and
Makemap software suite calculates accurate sensitivity
maps for circular ECT sensors with either internal
or external electrodes.
Flowan* off-line Multiphase
Flow Analysis Software
Image flows of fluid/fluid and fluid/solid
Data from the Tomoflow R100 system
may be saved to file for off-line flow structure analysis
using Tomoflow’s Flowan multiphase flow analysis software.
Example results are given here for several flow conditions
in a 50mm diameter pipe. The sensor used is a twin-plane
unit with 3cm long electrodes axially separated by 10cm
driven guard electrodes. The sensor is shown in the
photograph mounted on a 50mm perspex pipe ready to be
mounted in the test rig.
Images of flows are shown as circular
maps with a grid of 32x32 pixels using a colour scale
from blue (pixel empty) to red (pixel full). The example
alongside shows the arrival of a slug front in a horizontal
flow of plastic pellets in air. In this case the leading
plane is on the right. Flowan automatically establishes
the direction of flow .
Each image plane can be divided into
a number of zones – arranged appropriately for the flow
conditions. The example alongside shows a typical 13 zone
Flowan can calculate a number of
average parameters for each zone, including average concentration
and average flowrate. The example shows average concentration
(left) over several 10s of seconds, compared with the
instantaneous images (middle & right).
For each zone of each image plane the
concentration may be plotted against time. The example below
shows the area-average concentration in zone 2 (left hand
zone highlighted in white) of plane 1 in red, and zone 2 of
plane 2 in green. The flow shown is an upward flow of plastic
pellets blown by air at about 2 m/s. The average flowrate
of plastic beads is 750kg/hr upwards.
The first half of the graph shows
upflow - an upward-going slug with concentration going
from near 0 to near 1 in a short space of time at plane
1 (red line) slightly before arrival at plane 2 (green
line). It can be seen that the rear of the slug is travelling
faster than the front. On the second half of the graph
the green line shows concentration events at plane 2
(upper) preceding their arrival at plane 1 (lower plane
- red line).
Comparison of high speed photography
with the image cross-sections shows that the downward going
‘rope’ of solids (left hand side of page) is on one side of
the pipe – which is not obvious from the side-on photography.
The diagram on the right hand side of page shows the arrival
of the slug front.
Measure the velocity at any point or over
any zone in the flow-field
The velocity at each point in time
within each zone is calculated by correlating the instantaneous
concentration of one plane with the same zone in the
other plane. The result is plotted as a second graph
with axes in cm/second on the right hand side of the
graph. The blue line shows positive velocities (in this
case upwards) and the mauve line shows downward velocities.
It can be seen in this case that the slug front is moving
at 100cm/s bur the tail is progressing at 300 cm/s.
Measure the flowrate of a dispersed phase
as a function of time and space
The flowrate within the cross section
can be found by integrating the product of the velocity and
the concentration at each point in time. This gives the flowrate
per zone, and all zones can then be summed to give total flowrate.
Total flowrate (cm3/second) as a rolling 1 second
average is shown as the mauve line in the example above. For
an average flowrate in this case of 750 tonnes per hour (about
350cm3/sec) the peak rate is over 3000cm3/sec
- almost 10 times the average rate. Such details can be critical
in controlling industrial processes.
Comparisons have been made for downward
gravity flows through the same 5cm diameter sensor, using
plastic beads, small spheres and coffee powder. The results
above show the drop of plastic beads from a funnel under gravity.
The concentrations at plane 1 and plane 2 are given here for
the central zone, together with the velocity (blue line) for
that zone. It can be seen that there is an initial plug of
beads which pass between the two planes, dispersing slightly
as it does so. The velocity is fairly constant since the beads
are dropping freely under gravity.
The next figure (above) shows the overall
flowrate in mauve (cm3 per second, right hand scale,
summed over all zones) for the same case of plastic beads
falling under gravity, this time shown with the concentrations
in the two planes within the zone at the left hand side of
the pipe. It can be seen that the concentration in this zone
is greater in the second plane (red) – confirming the results
earlier that the initial plug is dispersing towards the edges
of the pipe. Integrating the flowrate for the entire record
gives a total of 1464 cm3, compared to the actual
value of 1490 cm3 – an error of less than 2%.
A summary of test results (above) for
a range of flows indicates that Flowan calculates volumetric
flow, converted here to mass flow rate, within typically a
few percent of the true rate.
Measure the volume of moving structures
within the section
In addition to being able to integrate
the total flowrate, the volume of individual structures within
the flow may be calculated. For example in the slug flow shown
above, the volume of the upgoing slug between about 5.5 and
7 seconds is 3392 cm3, equivalent to a 2 metre
long plug of solids moving at about 200 cm/s over 1 second.
The downward flow, although lasting just as long from about
8 to 9.5 seconds, only contains 252 cm3.
Tomoflow Flowan* brings
a new level of sophistication to multiphase flow structure
research. Tomoflow Ltd can either supply Flowan*
software for use with existing PTL twin-plane ECT systems
or we can provide complete multiphase flow measurement systems.
us for further information, pricing and delivery:
*Tomoflow and Flowan are
marks of Tomoflow Ltd
**ECT32, Makemap, IU2000
and Matect are marks of Process
Tomography Ltd (PTL) was established in 1994 to exploit
the research and development market for electrical capacitance
tomography (ECT) imaging systems and is the world leading
supplier of ECT systems. PTL has been leading an EU-supported
"CRAFT" research project for the last two years with UMIST
and other partners, on the feasibility of using tomographic
techniques in multi-phase flow measurement.