Fine Particle Software - Experts in Particle Technology - Computer-Aided Design of Separator Networks

Computer-Aided Design of Separator Networks

Series connections of particle separators with or without recycles are used to improve the performance of separation plant beyond that achievable with a single separator. Examples include cut size reductions or improved thickening in underflow series or underflow recycles, sharper cuts by re-classification or recycles and improved washing in co-current or counter-current washing trains.

Multiple pass system

The mass balances in such separator networks can be quite complicated, involving not only total mass and volume balances but also mass balances of particle size distributions. The problem however lends itself to solution by iteration with a computer.

If more than one separation stage is used for a given task, many or an infinite number of possibilities exist for the settings and sizes of individual stages, which need some method for comparison between settings and optimisation.

This new program provides a highly visual and interactive way of drafting series arrangements and calculating mass balances within networks of hydraulic separators such as hydrocyclones, sedimenting centrifuges or hydroseparators, with a view to finding the best arrangement for a particular duty and the required duty for each stage.

Simple separator

In the current version, flowrates, solids concentrations and particle size distributions are considered, and the user may manually design and/or optimise the network. An on-screen pointer is manipulated by a pointing tool such as a mouse. Tools for drawing any network are available on a pictorial menu, and can be rotated and scaled before being placed on-screen:

separator (specified by the flow ratio and a log-normal grade efficiency)
sump (for joining streams)
feed line (specified by flowrate, solids concentration and particle size distribution of the solids; this is in turn specified either by cumulative % undersize, or by three parameters of a bounded log-normal distribution)
instrumentation (for on-screen display of data selected from the information pages of any component of the system, by it a pipe, separator, sump etc.)
clean liquid supply (for supplying dilution or washing liquid; specified by flowrate only)
flow splitter (for splitting flows, in partial recycles; specified by a flow ratio)
overall plant performance monitor (for evaluation of overall plant performance, must be connected to system underflow, information available includes overall efficiencies, cut sizes, sharpness' of cut and grade efficiency curves (all of these actual or reduced), and the overall flow ratio)

Other tools include:

pipe (for connecting the equipment in the above list)
text (for on-screen legends, plant titles, notes etc.)

When dropped on screen, each symbol has buttons (revealed by pointing the mouse at the symbol) for deleting, moving or annotating the item and for accessing a control panel which is a data page containing given and derived information such as flowrate, concentration and particle size distribution. The instrumentation and plant control symbols have, in addition, a button for connecting them to equipment and another for selecting the page of information to be displayed in the window.

When the network is drawn and connected and feed items are specified the program begins iterating and this can be observed on screen with suitable instrumentation windows connected to chosen items. The iteration can be temporarily paused. The start-up can be watched as if in real time when the network is connected, loaded from disk or by pressing the reset button. Changes to input data can be made at any time and the effect of such changes observed on screen. Systems already drawn can be saved to or loaded from disk, a hard-copy print can be made and a network can be zoomed in or out.