The basic principles of electrical capacitance tomography (ECT) are to take multiple measurements at the periphery of a process vessel or pipeline and combine these to provide information on the electrical properties of the process volume.
ECT is applied to visualise multiphase unit processes to develop understanding; optimise performance and provide a basis of control.
The most common processes relate to multi-phase flows and fluidised beds.
An ITS electrical capacitance tomography system consists of:
- sensor array; these are sets of electrodes grouped in measurement channels. Each of which delivers a cross-sectional image. The electrodes can be set in 8, 12 or 24 electrode groups and these are most configured in circular array.The electrode array is held in place in a spool piece by the sensor body. Both can be made of robust materials to operate under challenging process conditions.
- instrument; ITS main ECT instrument platforms is the m3c which operates 1, 2 or 3 measurement planes.
- software; this provides three functions. Firstly it configures the instrument to fit the process conditions; secondly it analyses raw voltage measurements using inverse algorithms to provide a conductivity map; thirdly it has built in tools to allow analysis and export of tomographic data.
Electrical capacitance tomography was the second technology commercialised by ITS and many installations have been established around the world.
ECT platforms are often combined with ERT instruments to image multiphase flows in the petrochem sector.