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Jan 2017

What We Learned From WCIPT8: Part One

The 8th World Congress on Industrial Process Tomography (WCIPT8) was a roaring success. The biyearly congress attracts both renowned academics and industry professionals to talk about the groundbreaking developments within electrical tomography. Here, is a roundup of the projects that have got us the most excited:

Electrical Impedance Spectroscopy Tomography for Blood Flow Visualization

The traditional method of monitoring blood flow is through X-ray imaging; which shortcomings include the health risk associated with radiation exposure, the expensive maintenance and running costs and the slow processing time. Therefore, a stronger alternative is needed.

Electrical Impedance Tomography (EIT) provides solutions to the problems with X-ray imaging; it’s non-nuclear, inexpensive and provides real time data. The drawback of EIT however, is that the spatial resolution is inferior. Hence, the aim of this study is to prime tomographic techniques to provide clarity when visualising blood flow.

To do this the researcher circulated swine blood through a tomographic sensor, whilst altering the flow rate and the conductivity frequency. Whilst initially having limited success recording accurate data on a single conductivity frequency; the researchers later found promising results when creating a composite tomogram from two separate frequencies. By devising a new algorithm, to blend multiple conductivity frequencies, the researchers were able to reconstruct the change of blood capacitance when the flow rate changes. By registering clear capacitance measurements the researchers have devised a novel method to visualising blood flow.

Detection of the Shape of Liquid Metals using Electrical Capacitance Tomography

Gas-liquid two-phase flow is vital throughout all metallurgical processes. Monitoring these processes however, is difficult due to the high temperature and high density of liquid metals. The aim of this project is to investigate whether Electrical Capacitance Tomography (ECT) can be used to monitor the level of liquid metal inside vessels. A potential obstacle to gathering the measurements is wetting, and the possibility that liquid metal stuck to the wall of the pipe will affect measurement accuracy.

The experiment was conducted using the eutectic alloy GaInSn, which at room temperature is liquid. To test the metal it was poured into a vessel, containing a 12 electrode ECT sensor, 5cm at a time, with a reference being taken on each occasion more GaInSn is added.

Throughout the experiment the level of wettability varied, from leaving virtually no residue to leaving much. The unpredictability of the wettability did little to disrupt the ECT sensor as it displayed accurate readings of the rising amount of liquid metal within the vessel. With this in mind, the researchers warn about the problems posed by wettability on surfaces in which the liquid metal is guaranteed to cover in full, and recommend precautions are taken to protect the surface. Nevertheless, these results prove that ECT applications can be used successfully in the detection of liquid metals.

Case Study of Granular Flow in Silo, Based on ECT and Optical Images

Industrial storage containers, such as silos, are integral to a wide range of industries. Silos have two primary functions: to store and discharge granular materials. A reliable speed and quantity of discharge is pivotal to ensure industrial operations run efficiently and without error.

The purpose of this study is to investigate whether Electrical Capacitance Tomography (ECT) can accurately estimate the flow boundaries during silo discharging; to do this an experiment was conducted. The researchers obtained a transparent silo that allows one to customise the gradient and funnel flow. Dry brown rice was the granular material chosen to pass through the silo due to its high dielectric properties. Additionally, a CMOS camera was used to record the granular flow as point of reference against the ECT measurements.

The results gathered displayed a strong correlation between the readings captured by the CMOS camera and the ECT sensor. The researchers also go on to praise the ECT system for being non-invasive, as it provided information that the CMOS camera is unable to; such as the shape of the flowing zone. These findings highlight the great advantages ECT can have upon industries that utilise silos and flow rate.

  • Grudzień, Z. Chaniecki, L. Babout (2016). Case study of granular flow in silo based on ECT and optical images. WCIPT8. Iguassu Falls, Brazil. 26th-29th September.
  • Sapkota, et al. (2016). Electrical impedance spectroscopy tomography for blood flow visualization. WCIPT8. Iguassu Falls, Brazil. 26th-29th September.
  • Wondrak, M. Zhang and M. Soleimani (2016). Detection of the shape of liquid metals using electrical capacitance tomography. WCIPT8. Iguassu Falls, Brazil. 26th-29th September.