Control of Hydrocyclone Operation
In a beneficiation plant, during steady operation
the products from a hydrocyclone has a definite cut point. However due to
variations in the feed slurry characteristics and changes in the hydrocyclone
geometry, especially the diameter of the apex due to abrasion, the cut point
changes during operation. It is necessary to hold the performance at the
desired dsoc value for down stream operations.
The control strategy could be to monitor the
deviation of the cut point. The alteration in cut point was obviously due to
change in feed characteristics and additionally to changes in cyclone geometry
due to abrasion.
An important factor in designing control loops is
the instrumental and programmable time delays, the case of hydrocyclone
automation, the sources of time delays is given in Table1.
Each instrument has to have a separate time delay
factor which could be up to 3 seconds Programmable time delays introduced
during iteration could be greater than instrumental time delays.
Table1. Source of time delays in a hydrocyclone
circuit.
Fig. 1 shows the set up and instrumentation for
automatic control of a hydrocyclones.
The apex of the cyclone was fitted with a rubber
sleeve which could be pneumatically squeezed to alter its diameter. The vortex
finder was specially designed to travel up and down. The centrifugal pump was
fitted with a fiequency controller. The control strategy is illustrated in Fig.2.
Fig 1.Basic instrumentation for automatic control
of hydrocyclone
Fig2. Strategy for automatic control of d5Oc in
a hydrocyclone
Laboratory trials suggested that when a
hydrocyclone variable was subjected to a step change and the dsoc value
deviated, the operation of the hydrocyclone could be restored such that the
dsoc could be maintained to within ± 5 % of the calculated value. The
mathematical model used for calculations was derived to suit specific slurry
conditions. The conclusion was that such techniques could be developed for
automatic control of the cut point of hydrocyclones.
sinonine can also provide sand washing plant epc.
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