aat tech talk of adc concept video not tech talk topic

1. WELCOME TO
AAT TECH
TALK
NAME: B .Yogesh Kumar
Reddy
Department of ECE-b

2. TOPIC ON ...
Multiphase Flow Instrumentation and
Measurement Research in Brazil

3. Introduction...
In many industrial activities, the so-called multiphase flow is commonly found, which denotes the
simultaneous stream of two or more distinct substances. A typical example is oil-gas and/or oil-water
mixtures flowing through production pipelines in the petroleum industry. Flow behavior often
determines the efficiency and safety of plants and equipment where multiphase flow is present.
Therefore, monitoring of such flows and derived parameters is highly desired in many applications. In
the past, a number of measurement techniques and instruments have been developed and applied .
Multiphase flow instrumentation relies on a number of physical principles, including common
instrumentation and measurements that are based on electrical, sonic or radiation methods. This
paper shows three different sensors currently being developed in Brazil, which are based on electrical
measurements. They range from a simple phase concentration measurement up to multiphase flow
imaging. Each instrument offers a tailored solution with potential either for field applications or for
detailed multiphase flow investigation in pilot plant studies.

4.  Resonant Cavity Water-cut Sensor...
Resonant cavities are metallic devices where energy is stored in the electromagnetic
fields inside them. The resonance occurs when the average energy stored in the
electric field is equal to the average energy stored in the magnetic field, resulting in a
maximum concentration of energy inside the cavity. The geometry of the cavity, as well
as the dielectric characteristics of the material inside it, define its resonance frequency.
The resonance frequency is used as the measurement parameter, and it is related to
different measurement quantities, for instance, the water fraction in two-phase flows.
Measurements using water/oil and water/air stratified mixtures with fresh water and
seawater were performed in , showing that this technology presents adequate
accuracy for this application.

5. In , impedance matching networks for the resonant cavity sensor presented in were implemented
to of the measurements. The resonant cavity sensor consists of a PVC pipe inside a metallic
cylinder, as shown in detail in Fig. 1. The resonance frequency fr, considering the TE111
(transverse electric propagation mode in a circular waveguide), is given by
where k=5.69 m−1 is a constant dependent on the geometry of the cavity, c is the speed of the light
in vacuum, and εm is the effective permittivity of the mixture flowing inside the sensor's PVC
pipeline which is a function of the water fraction. In this case, as a function of the effective
permittivity, the resonance frequency is measured by an external circuit using the amplitude or
phase information of the transmission signal

6. Finally, the information is processed by a digital signal processing (DSP) stage and is associated with
the current water fraction. Fig. 1 shows the sensor (in detail) coupled to the circuit, which consists of a
phase locked-loop mechanism, where the resonance frequency is tracking according to the phase shift
caused by the water fraction flowing inside the PVC pipe. we can see the response curve of the
system, which relates the output voltage signal of the circuit to the percentage of water. This curve can
be identified and approximated by a fourth-degree polynomial equation.

7.  Electrical Capacitance Tomometry
In conventional volume-fraction measurement methods based on classical
electrical capacitance tomography (ECT), volume fraction values are
estimated by the cross-sectional images of permittivity distribution in two-
phase flow. A high-quality image is necessary to determine the volume fraction
precisely . Because reconstructing a high-quality image needs a complex and
time-consuming image reconstruction algorithm, it is difficult to meet the real-
time requirement of the on-line measurement Unlike the combining electrode
strategy applied to an ECT sensor, in the proposed method known as
electrical capacitance tomometry (ECTM), the number of grouped electrodes
is fixed, resulting in all measurements from just two electrodes . Thus, the
SNR remains the same as that of the two electrode sensor

8. Resonant cavity water cut meter coupled to
measurement circuit and the system response

9. A) COMBINING
CONFIGURATIONS FOR
AN ECTM SENSOR. THE
CIRCLED “1” AND “2”
DENOTE RESULTING
EXCITATION AND
MEASURING
ELECTRODES.
(B) SCHEMATIC
DIAGRAM OF THE
MEASUREMENT CHAIN.

10. • After carrying out N capacitance measurements, the Landweber Iteration method [6] is
used to estimate the normalized permittivity distribution (or normalized pixel values, gˆ(i))
and the water volume fraction is calculated by
• where Φ is the water volume fraction, M is the total number of pixels, gˆ(i) is the value of
the I'th pixel, and gˆ h (i) is the value of the I'th pixel when the sensor is filled with the
higher permittivity material (nominally 1)
• Thus, the SNR remains the same as that of the twoelectrode sensor. After measuring the
capacitance value (Fig. 2a), the electrodes are recombined, as shown in Configuration 2.
The same measurement procedure is carried out until the total number of non-combined
electrodes (N) rotations is implemented. For this work, the available number of
capacitance measurements is twelve

11.  Experimental Results
Experiments were carried out to evaluate the performance of the proposed method by using
static and dynamic stratified flow patterns. The ECTM sensor was built on a 76 mm
diameter polypropylene pipe. The twelve electrodes were fixed on the outer surface of the
pipe, each covered 28° along the circumference and 100 mm along the axial direction. At
each end of the electrodes, a 50 mm wide circular copper foil was fixed as grounded guard-
electrodes. Involving an external part of the sensor, a grounded shield was mounted to
protect the circuit from external electromagnetic fields. The ECTM system included a
500kHz sine wave generator, electrode control and DAQ modules. The NI PCI6259 DAQ
card was used to send switching control commands to the circuit and acquire the ac voltage
signal proportional to the capacitance. Fig. 3 shows the developed system

12. Overview of the ECTM system: (1) A sensor
with 12 electrodes, (2) Data acquisition, (3)
Electrode control module, and (4) Waveform
generator

13. 4. Static experimental results for stratified two-
phase oil-water mixture
5. ECTM sensor response in dynamic
experiments for air-water twophase flow.

14.  Wire-mesh Sensor...
Wire-mesh Sensor A technique similar to flow tomography is a wire mesh sensor . It
provides two-dimensional phase images of multiphase flow without the need to solve an
inverse problem. The sensor is a hybrid solution between invasive local measurement of
phase fraction and tomographic cross-sectional imaging. The sensor comprises of two sets
of wires stretched over the cross-section of a vessel or pipe. The planes of wires are
perpendicular to each other, thus forming a grid of electrodes. The associated electronics
measure an electrical property of the flowing media at each crossing point. Based on those
measurements and knowing a priori the electrical properties of the substances involved in
the flow, the sensor is thus able to determine instantaneous fluid distribution over the cross-
section. The first generation of wire-mesh sensors is based on conductivity measurements
[6], thus able to investigate electrically conducting fluids only. They are typically air-water
and steam-water systems, since it is only suitable to investigate flows where one phase is a
conductive medium

15. Typically the medium has electrical conductivity of at least 0.5 μS/cm. Wire-mesh sensors based
on capacitance (permittivity) measurements were introduced by Da Silva et al. due to the
importance of investigating the occurrence of non-conducting fluids, for instance, oil or organic
liquids, in several industry applications. The phase fraction distributions in a flow cross section,
such as in a pipe or another vessel, can be determined by discriminating fluids with different
permittivity values. However, this technique presents some limitations, and up to now investigated
flow phenomena could comprise only two substances, mainly gas-liquid or liquid-liquid but also
solid liquid flows In recent years, some efforts have been made to improve the range of application
by applying dual-modality. measuring techniques in which two different sensing techniques are
used to distinguish more than two substances. Therefore, a capacitive/conductive wire-mesh
sensor was proposed in by which signal excitation composed of two distinct frequencies is applied
to interrogate each crossing point of a mesh sensor. Each frequency is linked to either the
conductive or the capacitive part of the fluid's electrical property.

16. SCHEMATIC
REPRESENTATION OF A
WIRE-MESH SENSOR.
(B) PHOTOGRAPH OF A
TYPICAL LOW-
PRESSURE SENSOR.

17. 7. Visualization of wire-mesh sensor data for
superficial gas velocity of jG = 2.5 m/s and
different liquid superficial velocity range of 0.25
m/s to 2.50 m/s.

18.  Flow Measurement...
The measurements were conducted in a test facility of the Multiphase Flow Research
Center at Federal University of Technology - Paraná (NUEM/UTFPR). The facility
consisted of a horizontal acrylic pipe of 25.8 mm internal diameter and total length of
~9 m. Tap water was circulated in a closed loop with the help of a pump and a
gravitational separator/storage tank. Air was injected into the pipe through a
compressor to form a two-phase flow. Flow rates of both fluids were independently
measured. The wire-mesh sensor was located at 7.5 m from the pipe entrance.
Experiments were performed at gas superficial velocities of 2.5 m/s and at liquid
superficial velocity range of 0.25 m/s to 2.50 m/s. The wire-mesh sensor (with 12 × 12
wires) was set up to acquire images of the flow at 5,000 fps during 5 s.

19. . Axial slice images of flow experiment: (a)
Permittivity distribution. (b) Conductivity
distribution. (c) Fused image of phase
distribution

20. The transition of a few different flow regimes can be visualized in the
temporal evolution of the phase fraction values taken from the crossing
points along the central electrode. Thus, such an image provides a side
view of the flow on a horizontal plane cut through the pipe along its
vertical axis. The gaseous phase is represented by a dark color and the
liquid phase by a bright one. The horizontal axis represents the time of
5 s. show the system's capability, dynamic tests were also performed. A
multiphase flow loop at Federal University of Santa Catarina was
capable of providing gas-water flows at several flow regimes (bubble,
annular, slug, and stratified). This flow loop had a 3 in (7.62 cm) inner
diameter and a 5 m long test section. Air and water mixtures at different
conditions were monitored with the ECTM sensor. For each
experimental test, a reference water volume fraction was obtained by
means of a quick closing valve method. The estimated water volume
fraction is depicted
This Photo by Unknown author is licensed under CC BY-SA.

21.  Gas-Liquid-Liquid Three-phase Mixtures
Dual-modality wire-mesh sensors have been used to investigate three-phase gas-oil-water
flows, generating images of conductivity and permittivity distributions over a pipe cross
section . A pipe segment was filled with air, oil, and water and was shaken in such way to
produce waves on the stratified mixture. The agitation process was monitored by the wire-
mesh sensor (with 16 × 16 wires) installed in the middle of the pipe section. depicts axial
slice images which were produced by taking the values from electrode number 4, i.e.,
along a central chord of the pipe. show measured permittivity and conductivity,
respectively. To convert this pair of images into phase fraction distributions, appropriate
methods of data fusion must be employed, obtaining individual phase fraction of gas-oil-
water flow. In, a parameter model is fitted to the measured electrical parameters
distributions, which is then applied to obtain phase fraction from measured data. shows
the obtained fused image for the phase fractions.

22.  CONCLUSION
a short review is given of the Brazilian research landscape of multiphase
flow instrumentation. Three different sensor systems for multiphase flow
monitoring based on electrical measurements have been presented.
Hence, water content in oil-water flow can be correctly determined by a
microwave resonant cavity sensor. A second sensor based on multiple
capacitance measurements, known as an ECTM sensor, correctly
determines the void fraction of gas-liquid two-phase flow. Finally, a wire-
mesh sensor allows detailed images to be generated of flow behavior
based on impedance or complex permittivity measurements. Each of the
instrumentation presented can produce reliable data for future application
in research studies or industry

23. This Photo by Unknown author is licensed under CC BY-SA.