AS_2

CONTROLLO

tecnica

Marzo 2017

Automazione e Strumentazione

Definition of Control System in Chemical and Petrochemical Plants requires specific know-how with the target

to optimize and improve existing systems and design new ones. When designing a system, it is necessary to

follow some basic steps like modelling the system, analyse such model, design the system/controller and finally,

implement it and test it. In order to bridge the gap between the strong and deep knowledge about classical

control techniques and the new process simulation features, Inprocess proposes a simulation-based course,

targeting process control engineers, where the right combination of theory and practical exercises is fulfilling

such professional needs. Training could be extended to Multivariable model predictive control (MPC) topics.

JoseMaria Ferrer

Josep-Anton Feliu

Incorporating Process Simulation

into Control Engineering

Control engineering

is the engineering discipline

that focuses on the modelling of a diverse range of

dynamic systems and the design of controllers that

will cause these systems to behave in the desired

manner. Although control engineering has diver-

sified applications that include science, finance

management, and even human behaviour, our

intention is to focus on its utilization in

Chem-

ical Engineering

as applied to the processing

industries. The field of control within Chemical

Engineering is often known as

Process Control

It deals primarily with the control of variables in a

petrochemical/chemical process in a plant.

Looking back at the control engineering history,

chemical engineers were slow in adapting the

benefits of existing control literature (developed

originally for other systems like amplifiers, ser-

vomechanisms or mechanical systems) to the

design of process control schemes applied to the

hydrocarbon and chemical processing industries.

Initially maybe due to the unfamiliar terminology,

but there was also the basic difference between

chemical processes and mechanical or pneumat-

ical systems which provoked this postponement

of process control theory and its industrial imple-

mentation. Hydrocarbon and chemical processes

are intended to operate normally at a constant set-

point, and process disturbances impacts are mini-

mized by the presence of large-capacity elements.

Opposite, such elements would tend to slow the

response when controlling mechanical systems.

Similarly, the effect of time delay or transport lag

is one of the major factors in process control but

it is rarely considered in references dealing with

mechanical systems. In the processing indus-

tries control systems, the presence of interacting

first-order elements and distributed disturbances

is much higher than the second-order elements

present in the control of mechanical and electrical

systems. The described differences made many

of the examples of design of control of servo-

mechanisms of little use to those chemical engi-

neers interested in controlling the processes in the

chemical and hydrocarbon industries

[1]

L’AUTORE

J. Ferrer, J. A. Feliu - Inpro-

cess Technology and Consulting

Group, S.L.

PROCESS SIMULATION FOR CHEMICAL AND PETROCHEMICAL PLANTS

Incorporare la simulazione di processo

nell’ingegnerizzazione del controllo

Definire sistemi di controllo di impianti chimici richiede un know-how molto particolare, teorico ed operativo, allo scopo di analizzare e

migliorare i sistemi esistenti e progettarne nuovi per soddisfare esigenze specifiche. Nella progettazione di un sistema, è necessario seguire

alcuni passi fondamentali come modellazione del sistema, analizzare tale modello, progettare il sistema di controllo e infine, attuare e veri-

ficare il controllo implementato. Al fine di colmare il divario tra la conoscenza classica delle tecniche di controllo e la moderna simulazione,

Inprocess propone dei corsi, alternando teoria ed esercizi pratici per coprire le diverse esigenze professionali e colmare eventuali lacune del

personale di ingegneria o operativo. I corsi possono estendersi al Controllo Predittivo Multivariabile (MPC).