By Rob Lanham, General Manager, Ross Systems & Controls
Click here to download this complete article in PDF format.
The business of creating an efficient mixing or
blending system is a spectacular balancing act.
The throughput you require must be balanced
against batch size, agitator sizes, motor sizes, shear
and tip speeds, viscosity, the thermal capacity of your
product and heat-transfer media, energy costs, labor
costs… and a hundred other variables.With so many
equipment choices and tremendous competitive
pressure to optimize performance, the mixing
process itself has never been more complex. But in
most cases today, the most challenging balancing act
of all is still the specification of your process control
The process control system must balance your
need for accuracy, consistency, flexibility and reliability
against your need to control costs. This is why the
control is now much more than the interface
between the operator and the machine; it's a direct
interface between your process system and your bottom
line. Specify the process control equipment
intelligently, and your production line will hum.
Under-specify or over-specify the control system,
and you're in for an avalanche of costs and delays.
Years ago, the control system and process control
equipment were often little more than an afterthought
assigned to a local contractor (who knew
almost nothing about the process he was trying to
control) and an overworked in-house engineer.
Those days ended with the realization that the modern
control is far more than a fancy digital version of
an ON/OFF switch.
With the technology available today in sensors,
integrated PID control logic, intelligent valves and
central SCADA systems, every function in your processing
system can be automated to operate at a terrific
level of accuracy. But as accuracy increases, costs
increase, too — and at an even faster rate. And this is
where the most important balance of all becomes
apparent: the balance between the accuracy that can
be achieved and the accuracy needed.
Charles Ross and Son Company