Frequently Asked Questions
What is process tomography?
How do you fit sensors into the process?
Will it work with my process?
What's the resolution?
How much does it cost?
What is process tomography?
Process tomography is based on taking a number of measurements of a process from a sensor and combining these to provide information on the distribution of material within the volume of the sensor.
Elements of the technology are similar to medical tomography (CAT scanning) only electrical tomography is less expensive, faster and more flexible.
How do you fit sensors into the process?
Sensors have been fitted to autoclaves working at 280°C and 20 bar and also taken into processes operating at -28°C.
For an existing vessel, the most suitable technique is to us a baffle based probe. For pipelines a flange-based spool piece can be used.
For research vessels, sensor arrays can be emplaced using a cage or built into the vessel during its commissioning.
Will it work with my process?
Scale:
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Sensors can be made with diameters from 5mm up to 2m and lengths from 5cm to 4m.
Materials:
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Electrical tomography systems can work with a very wide range of materials ranging from air and non-conducting fluids (using capacitance techniques) to water and polar organic solvents (using resistance techniques). The most common materials which present significant challenges to the current technology are very highly conducting systems (such as molten steel). Resistance tomography systems for use in food and pharmaceutical environments are available and intrinsically safe systems are also available.
Operating Conditions:
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Tomography systems can be used in a wider range of temperatures, atmospheres and processes. Resistance tomography can be used in metal walled pipes and vessels in the presence of metal internals (such as down pipes and impeller shafts). However a substantial quantity of metal internals (such as metallic packaging) or highly conducting systems (such as concentrated acids and molten metals) can present a challenge.
What's the resolution?
This is a complex question as "resolution" means different things to different people:
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Temporal resolution is 30 milliseconds per frame for the standard measurement method. This can be reduced to less than 10 milliseconds for rapid data collection (although slightly reduced spatial resolution)
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Concentration resolution is better than 1% under normal operating conditions
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On-line spatial resolution is based on a 20x20 matrix yielding 5% of the vessel diameter for a circular sensor geometry
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Off-line spatial resolution is 2-3% using the ITS advanced tomography software toolsuite. Spatial resolution can be enhanced to better than 1% using tailored reconstruction techniques where an understanding of the process is used in conjunction with the tomography system
How much does it cost?
This depends on the complexity of the process, the process conditions and what you are trying to measure. Where ITS does not have prior experience in a particular application area we will usually carry out a free screening exercise to confirm the technology is appropriate, followed by a feasibility study.
