Pierre Latour discusses issues with realizing the full commercial potential of proper control system performance indicators and argues that his method, Clifftent, can help mitigate problems and maximize profit. He outlines how Clifftent uses calculus and statistics to determine the optimal setpoints and limits for process variables to locate the maximum expected profit. Latour claims that adopting Clifftent's performance-based licensing approach in the 1990s could have led to a healthier and more profitable industry today.

1. HPIN CONTROL
PIERRE R. LATOUR, GUEST COLUMNIST
clifftent@hotmail.com
APC for min maintenance or max profit?—Part 2
While I have promoted proper control system performance
indicators'""^'' since 1964, like Dr. Y. Zak Friedman,' 1 also am
,iware of some deeper problems with realizing its full commercial
potential.-*'"""*''^'^'^' Friedman once piiblically claimed Clifftcnt"^'^
w,is no panacea,"' without seeing ii in action. Moreover, he
LÍi.irged, without any basis, that C'liHtenr, a mathematical pro-
cedure, could lead to burning down a furnace. My experience is
proper deployment of CÜiflrent to operate the HPI would mitigate
Micb events''' because ii mandates caretul modeling ofthe financial
consequences of exceeding properly set limits like burning down
liirnace.s, so operators would be using better information and
models to make appropriate .sctpoint decisions for risky tradeoffs.
I >etermining .sucb effects rather than ignoring them is the main
idea of science, mathematics and engineering. I refrain from blam-
ing MVC^, I'll), IP. SQC. feed-forward, inferentials, six-sigma,
.statistics, talculu.s or tiialhematics for burning down furnact'.s.
I have published practical examples ol using Clifftent to calcu-
late APC benefits many times for real applications'"'''''*'"^^'^*' since
[be tow-MiIlur fuel oil example^'* in HP, December 1996. I bavc
.1 library ot commercial oil refmery, olefln, aromatics, polymer,
synluels, chemicals and gas processing applications now. Every
single one is a success because it determines a profit improvement
(.sometimes small) and bow to achieve it. I recently sbowed^^ how to
(¡uaiitify the value of Friedmans alkylation control approach."^''
As for how Clifftent works, 1 have published that
too^"''''^''^*^'*'^^''^* and will repeat it here. Every controlled vari-
-ible iCV) has a risky profit tradeoff. Calculus and statistics teach
integration ofthe product of a data frequency di.stribution with
its associated profit function gives its average (expected value)
profit. Repeated integrations witb incremented data means give
ihe average profit profile vs. data mean; a smooth hill (for any
sianilard deviation >Ü). It's easy to locate the hilltop max profit
.md corresponding optimum data mean. Thats how all HI'l
sctpoints, limits, targets and specs are set now, although witb less
rigor. That's also bow C.VIKPi profit meters can be built. ' 1 he
HPI received the panacea in 1996."'
A Canadian University ChE Department included deter-
mining dynamic system financial performance, ClifTtent, in
it.s process control course in September 2009. Hopefully this
rekindled academic interest in process control and research on
building Clifftent models for integrated alarm management,
process maintenance and safety. Once a set of candidate CKs
;ind related manipulated variables (Af Ks) are established and
I be pracess operation and économies are known, good process
control engineering practicc^'^'''''^'^'^'"^^'^'* calls for determining
tbe economic sensitivity of eacb CV, their Clifftents and a vari-
,nice reduction claim for each control system design, providing
ihf appropriate sctpoint determination method and benefit for
ihat variance reduction. 7 hen the process control engineer is in a
•>olid position to design, m;untain and improve the Instruments
and control system, the process operator is in a sound posiiuin to
use it and operating company management understands it.s role
and value. They finally have a chemical engineering method for
operation that is pragmatic, prudent and profitable.
ln hct, 1 claim had one or iwo computer-integrated manufaciur-
ing (CIM) solution suppliers adopted pcrtormancc-based licensing
when it was commercialized in the mid-199üs,^"'^'^'*'^^ the land-
scape of the APC, and (^IM business in the HPI today would he
healthier, more significant and more profitable lor those suppliers
and their operating company partners. And much misguided effort
and cxpcase would have heen avoided. fViedman wouid certainly not
he proposing in a 2009 HP editorial forgoing .ÍO'^íi of APC'.perfor-
mance, worth >$ü.3()/bbl crtidere-fined,to reduce AI'C. maintetiatice
cxjsts. It would not he pragmatic, prudent or profitable.
Dr Y. Zak Friedman's HPln Control editorials continue to
serve the HPI. 1 hope I can add to them on occasion. W*
LITERATURE CITED
'" l^tour. V. R.. "Why Invesi in PRt}CRSS CONIROL?". CONTROL Vol.
XV. xS. May 2002. pp. 41-46.
''' l^aiiiur. P R., "Why tune control loops? Wby mdte control loops?", ediio-
rial guest columnist, Hydrocarbon Processing, V8I. n9. September 2(102. pp.
'" McMahon.T K., (& P. R. Latour). "CLIFFTENT For Process Optimization."
CONTROL VI7. nl2. December 2004, p. 66.
'' l^tdur. P R., "Detisions about risk reduction." litter to Editor, Hydrocarhon
Processing, V80. n6, June 2001, p. 3').
^^ Latoiit. I'. R.. "Quantifying financial values", HP In Control Guest Columnist.
Hydrucarhm lhvcrssir,g.V%{i, n7. July 2001. pp. 13-t4.
'' ljtoiir. P. R., "Align alkybiion separaiiiin to economics." HPln Cx)ntrol
liditorial, Hydrociirbiiti Processing, VHS. i i ! , lanuary 2009. p. 98.
^'' Latour. ['. R.. "Process control: t'l.ll'i'TIÍN I siiows its more profitable than
ex|TecEed," Hydnittirhon froressing, V7'i, nl2. December 1')%. pp. 7S-H().
Repiibliühed in Kane. [.es. VA, Aduamrii Process Control ami Informniion
Sysifim for the l^ocess ¡ndustrirs. Gulf Piiblisliing, Co. I')')'>. pp. .ÍI-37.
^'' Ldoiir. P. R.. "CLIFHIHNT: Determining I-ull Financial Benefit from
Improved Dynamic Performance." PajierCOI, ihirJ Intcrnarioual Conference
on l-dundaiions of C)mpurer-Aided Process Operations. Snowbird, Utah.
)uly "i—IO, l')')8. Proceedings published in AlChK Symposium Series No.
320. V94. 1998. pp. 297-302.
^'' Baker. J. A. et ul. "The Rc]X)ri ofllie BP U.S. Refineries Independent Safety
Review Panel." January 2007.
^' Friedman, Y. Z., (& G. D. Martin. P R. Latour). "APC Survey," Exchange of
Ixiiters to the Fldiior, Hydrocarbon Prficessirig., V85. nlO. OttoUr 2006. pp.
45-46 and V85, n i l . November 2006. pp. 45-52.
'" l^tour. lî R.. "Align Olefin Operations to Lxonomics - Clifiicnt optimizes
scipoints." pn-senteil at 2007 Spring AlChF. Meetinj^ Ethylene Producers
Conference, Houston. Tex;«, April 2^. 2007. Published in t^onfcrcnce
Proceedir^s CD.
''' Fricdnian. Y. Z., "Alkylatioti prcKluci separation control," HPIn Conttol
editorial. Hydrocarbon Processing, V87, n9. September 2008, p. 178.
The author, president of CLIFFTENT Inc., is an independent conr.ulting chemic.il
engineei specializing in identifying, capturing and sustaining measurable financial
value from HPI dynamic process control, IT and CIM solutions (CLIFFTENT) using
performance-based shared risk-shared reward (SR2) technology licensing
HYDROCARBON PROCESSING NOVEMBER 2009 13

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