Using Mechatronics for the Interpretation and Modelling of the Pressure Filter Cycle

Abstract

SUMMARYAn experimental apparatus combining the principles of mechatronics with a dead-end pressure leaf filter is described. The computer controlled and sequenced apparatus was used to monitor performance during the cake formation, gas dewatering and displacement washing phases of filter cycles. Data relating to cake properties and liquor transport rates were acquired through electrical resistance measurements and suitable transducers. The data illustrate the versatility and accuracy of the apparatus and they are used to compare with predictions given by existing theories, particularly for cake formation. Batch experimental results obtained with aqueous suspensions of calcite are shown to compare favourably with theoretical predictions for important design parameters such as cake height and cumulative volume of filtrate whereas data for more compressible talc systems tended to show more deviation. The work presented highlights the benefit of a mechatronics approach to experimentation and emphasises the importance of data acquisition and system control to future developments in filter design.

Using mechatronics technology to assess pressure filtration

“…Other examples of similar data have also been obtained and some aspects of accuracy and repeatability for parts of the apparatus have previously been described [11,18]. In brief, experimental data could be repeated with some confidence provided normal care was taken in preparing the feed suspensions.…”

“…[2][3][4][5][6][7][8][9][10][11]. Whilst this mode of filtration is relatively easy to perform in the laboratory it is not always employed in industrial scale filtrations.…”

The use of electrode probes in determinations of filter cake formation and batch filter scale-up

“…When the probes were connected the computer controlled the switching of the electrode pairs to allow reversing polarity resistance measurements. These were recorded and then converted through calibrations to give real time measures of transient cake thickness and porosity distribution (see also Tarleton andHancock (1997) &Holdich andSinclair (1992) for more details). Wherever possible experiments were repeated to ensure reproducibility.…”

“…By using small intrusive electrodes, rather than (for instance) the larger flush mounted variant or pressure transducers, the number of probes available to give measurements during filtration is substantially increased. Moreover, such electrode probes can offer significant advantages over many of the other techniques shown in Table 1 whereby measurements are taken relatively quickly and there is the potential for determinations of liquor and solute transport rates during all phases of a filter cycle including cake deliquoring and washing (Tarleton and Hancock (1997)). …”

Using statistical and artificial neural networks to predict the permeability of loosely packed granular materials

“…For the modelling and regression based techniques the data (total of 547 points) was obtained from previous studies [5,15,[51][52][53][54][55][56]. The results are compared with the predicted values from the particle size analysis data using analytical models (K-C and H-B).…”