Raw mix virtual silo control

I have never heard of it, but imagine you work to produce a virtual batch of however many tonnes of raw mix. This would prevent the mix proportions being changed too frequently in response to random variations in mix composition. A better way of achieving the same thing would be to use statistical process control and control charts.

electron1539:

did any body have know how the virtual silo raw mix control system work 

Hello Electron1539,

The use of a 'virtual silo' is common to most automated raw mix control systems on the market. And, as Michael rightly pointed out, the 'virtual silo' is used to dampen out incremental changes to the corrective material feed rates. These adjustments are regularly calculated by the blending system software generally every 5 -10 minutes, based on aggregated cross-belt analyser analysis values.

The variables generally used to set up the 'virtual silo' are silo volume (in tonnes) and a property called 'elimination time' (in minutes/hours), which is the time given for the software to correct the silo contents to target.

For a given silo volume the elimination time controls the degree of dampening induced in the blending system by the 'virtual silo'.  For example, if the elimination time is increased, the control system will make smaller incremental changes to correctives weigh-feeder rates to achieve the raw meal targets because it has more time in which to achieve the raw meal targets.

Reducing the elimination time will have the opposite effect, because the targets then need to be achieved in a shorter time.

This is a very simplified description of how it works, but it is important to note that for any software-based blending system to work efficiently a cross-belt analyser is essential.

One such system is the "QCX Blend Expert" by FLS, another is the "OptimizeIT Raw Mix Preparation" by ABB.

Best regards,

Ted.

Hi,

 This is conventional, oe better say a premice in the calculation to adjust your ex_mill raw mix quality, you may consider you actual setting as a virtual bin (with composition as per your periodical control sample), then calculate the +/- adjustments you have to apply on weighfeeders. This is the one best way to obtain stable operations and can be computed according to plant and raw materials specificities, then installed as automatic on stream controller  software.