Page 20 - Industrial Plants 2014

standard deviation of about 45 % compared to the
case with normal DCS control.
The implementation of APC allowed the plant to
operate with lower steam usage. As plant operators
gained confidence on the controller, additional
space was given to the steam ratio setpoint,
allowing a progressive reduction of the specific
steam usage.
The following trend (figure 9) shows the specific
steam usage over about one year, with an overall
reduction of about 15%. This resulted in large steam
savings, whose potential value can be estimated in
Fig. 7 - MPC stage, a number of settings and limits have been the range of 300 keuro/year.
controller service implemented on both DCS and P&C controller side. Further to this, the customer experienced additional
factor benefits in terms of reduction of operator’s activities
and daily tasks, which resulted in additional time
Results that could dedicated to other tasks.
Advanced controller is in operation since late 2010
and has led to significant benefits both on process
operability and economic returns (figure 7): Conclusions
In conclusion, final results prove that APC is a
SF= MPC Operation Time / Total time, Oct. 2012 [4] valuable technology supporting plant owner and
managers in the implementation of Watergy concept
The chart of figure 8 shows the pH control results [5]: this term is becoming more and more important
over a one week period with indication of the limits. for industries having to deal at the same time with
pH control with APC showed a reduction in variable crucial factors like environmental and operation

Fig. 8 - Results from pH
control over a 1 week
period (band = 0.3)

Fig. 9 - Specific steam
usage unit since MPC
activation

IndustrIal Plants - May 2014
16