Chemical Engineering February 2012 - 46

Solids Processing
a change, in order to maintain the future
prediction-horizon period. This
is termed " realtime receding horizon
control " and is characteristic of model
predictive control.
Here, a number of loops are operating
in tandem (Figure 3). Manipulating
clinker feedrate and separator
speed controls product quality. These
same two parameters are also used,
together with air flow through the
mill, to drive separator feedrate (measured
as elevator power) toward a defined
high limit. Air flowrate through
the mill and exit water spray variables
control the temperature of exiting
material. Finally, a stabilizing loop
minimizes a function defined as " mill
condition " , calculated from the rate of
change of elevator and mill power. The
online particle-size analyzer measures
product quality in real time, providing
vital information that is used by the
model in combination with an array of
other process measurements.
The installed solution has pushed
the circuit into a new operating regime,
uncovering better control strategies
than had been identified through
manual operation. Significant benefits
have accrued, including the following:
* A 20% reduction in specific energy
consumption
* An improvement of 15% in one-day
strength levels (a primary performance
indicator)
* An increase in throughput in excess
of 15%
These savings are not individually attributable
to either the analyzer or the
control package but arise from symbiosis
between the two, which has unlocked
the full potential of each. The
payback time for the entire project is
estimated at just over one year, based
on energy savings alone.
Conclusions
The automation of process analysis
and its closer integration with plant
operation presents an opportunity for
improved control, reduced risk and financial
gain. For online particle-size
analysis proven automated systems
have developed to the point of widespread
availability, making this opportunity
financially and technically
feasible across a broad range of manufacturing
sectors. Options for investment
now range from fully integrated
turnkey solutions to sensor-only purchase
for in-house implementation.
Continuous, realtime analysis of a
critical variable, one that directly influences
product performance, provides a
platform for developing and implementing
the very best automated control
strategies for a given application.
Such strategies deliver multiple economic
benefits in the form of reduced
waste, increased throughput, enhanced
product quality, reduced manual input
and lower energy consumption. Automating
control realizes the full potential
of realtime analysis, extracting
maximum return from an investment
in process analytical technology.
■
Edited by Rebekkah Marshall
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References
1. Ferrari, A. and Pugh, D., Marble fillers made
to measure, Industrial Minerals, Aug 2008.
2. http://opcfoundation.org/Default.
aspx/02_news/02_news_display.
asp?id=740&MID=News
Authors
Jeff DeNigris joined Malvern
Instruments in 2005
as national sales manager,
process systems to focus on
supplying online, realtime
particle size analyzers to the
pharmaceutical, fine chemical,
mineral, toner and cement
markets (Address: ; Phone:
XXX-XXX-XXXX; Email: ).
He graduated in 1989 with
a B.S.M.E. degree from Widener
University, College of Engineering in Pennsylvania.
He has spent most of his career in the
manufacturing sector with top original equipment
manufacturers of capital equipment. Particular
focus was given to the plastics industry in
the sales and marketing of recycling and reclaim
systems, and to the design and implementation
of granulation and separation systems.
Contact The YGS Group
at 717.399.1900 x100 or
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www.theYGSgroup.com/reprints
The YGS Group is the authorized
provider of custom reprints from
Chemical Engineering.
Alberto Ferrari is the production
manager of Ferrari
Granulati S.A.S., a leading
producer of marble chips and
powders, situated in Grezzana
(Verona) Italy. He is a specialist
in the fields of information
technology and industrial
automation, working for five
years as R&D manager in
Dellas S.p.A., a producer of
diamond tools, before returning
to the family company in 1995. He continues
to work to improve the efficiency of milling and
sieving plants for calcium carbonate minerals.
44 CHEMICAL ENGINEERING WWW.CHE.COM FEBRUARY 2012
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