Process Control

6. Terminology

• Process Dynamics
• Process Variables
  • measured
  • controlled
  • manipulated
  • perturbation
• Process Stability
• Open loop
• Closed loop
• Setpoint
• Error
• Feedback
• Feedforward

7. Instrument symbology

• Instruments
• Signals
  • Pneumatic (0.2 - 1.0 kgf/cm²)
  • Electronic (4-20 mA; ON-OFF)
  • Digital (software)
• Final control element
  • Control valve
  • Frequency variator
  • Stroke in alternating pumps
  • Tiristors
• Controller

Instrument tagging conventions

first letter: type of variable		other letters: instrument function
A	composition (analyzer)	A	alarm
B	flame	C	controller
D	density	E	sensor
E	voltage	G	gage
F	flow	I	indicator
H	hand, manual element	Q	totalizer, accumulator
I	electrical current	R	register
K	time	S	switch
L	level	T	transmitter
M	humidity	V	valve
P	pressure	Y	other functions
S	speed
T	temperature	2nd letter: modifier
W	weight, mass	D	differential
X	other instruments	F	ratio
Z	position

Process variable modifiers: "F" in the 2^nd position indicates "ratio": FFI is an indicator for a ratio of two flow rates; "D" in the 2^nd position indicates "differential": PDI is a differential pressure (delta p) indicator.

Function modifiers: as the last letter(s) of a "TAG" for alarms and switches: H, HH, L, LL

Combinations such as FRC PDIC FQIT FIT PDALL are frequently used.

8. Course contents

Objective

to understand, evaluate and design process control systems

Methodology

knowledge of visualization tools
basic theory
knowledge of tools for analysis
advanced theory

Planning and goals

Introduction	Objectives Basic concepts	WHAT TO STUDY?
Mathematical Modelling	Transient Phenomena Differential equations	HOW TO MODEL?
Process Simulation	Numerical Methods Programming	HOW TO SOLVE?
Control (time domain)	Conventional Control Advanced Control	HOW DOES IT WORK?
Control (Laplace/ frequency domains)	Stability Identification Properties	GENERALIZED CONCEPTS
Digital Control Systems	Industrial Application	HOW TO USE IT?