Whilst the basics of the filtration and drying process are well understood, the actual performance of filters can be subject to a high level of variability.
ITS has been involved in the measurement and understand of different filtration and drying processes for over 10 years.
Electrical resistance tomography (ERT) was originally applied as a basis for determining presence of water in filter cakes, and has been applied from pilot scale through to full production in 36m3 filter driers. Depending on process conditions, ERT has able to operate to around 5% level of dryness. Data within this range provides a good basis for identifying drying trends and can help anticipate problem batches.
Lower levels of dryness can be measured using electrical capacitance tomography (ECT) which can measure less than 1% moisture levels. ITS has also developed an algorithm for applying ECT under wet conditions (which was not possible previously). This allows non-contact measurement of the drying of cakes (although is difficult to apply to the interior of filter vessels).
ITS has experience of a variety of sensor deployment strategies. It should also be noted that ERT systems can be deployed in ATEX environments should this be required. Cycle times from a few hours to several days have been measured, and continuous operation of instrumentation carried out over a number of months.