process control importance

1. 9/21/2023 1
Topics & LLOs of IPC course – class 1
 Topic1: Process Control System (PCS): Block diagram of PCS; Example
(Stirred tank heater system)
 Topic 2: Importance of Servo & Regulator problems
 Learning Objectives (LOs):
This class will develop students’ knowledge in/on…
LO1:process control system & its importance
 Lecture Level Outcomes(LLOs):
After completion of this class, students will be able to…
LLO1:draw & identify the blocks of PCS
LLO2: distinguish between servo & regulator problems
Course Discussion Topic1 (CDT) on IPC course

2. 9/21/2023 2
Process & its variables
Course Discussion Topic1 (CDT) on IPC course
Process control system block diagram

3. 9
Temperature control system implemented
with industrial components:
Sensor Regulator Aktuator

4. TC
TT
Sensor Controller
Actuator
Temperature
setpoint
Measurement
signal
Control
signal
Water temperature =
process variable
(TT = Temperature Transmitter)
(TC = Temperature Controller)
Piping & Instrumentation Diagram (P&ID)
for the temperature control system:
Room temperature = process disturbance
10

5. 10
Application of Process Control System (PCS):
STH system

6. Simulation model
13

7. t t
Max
limit
Min
limit
Without control or with
poor control
With good control
Setpoint, ySP
Process output, y
Less error!
(Smaller variance)
Control error,
e = ySP - y
Specifications about
control error
not satisfied!
Importance of control: Automatic control is making
process variables stay sufficiently near their setpoints
(references)
- automatically (i.e. without manual operations):
2

8. Common process variables
to be controlled to follow setpoints:
• Temperature (heat exchanger, reactor, room)
• Pressure (reactor, oil/water/gas-separator)
• Flow (gas or liquid flows in pipe)
• Level (tank)
• Position (ship, robot)
• Rotational speed (motor)
3

9. • Product quality
• Product economy
• Safety
• Environment protection
• Comfort
• Feasibility
• Automation
Areas where automatic control
can make large benefits:
4

10. So, how does the controller act?
t
It manipulates the process variable by changing
the control signal to the actuator
until the control error has become zero. So, it
continually improves, until the aim is reached:
Zero error.
In practice it is the mean error which will be
zero as there will always be some disturbances
making the error vary somewhat, see the figure
below.
Process variable
Setpoint
Control error
= Setpoint - Process variable
11

11. 9/21/2023 11
LLOs revisited
Course Discussion Topic1 (CDT) on IPC course
CDT1 - LECTURE LEVEL PRACTICE PROBLEMs/ QUESTIONs
(LLPs/ LLQs) to test the LLOs
 Lecture Level Outcomes(LLOs):
After completion of this class, students will be able to…
LLO1:draw & identify the blocks of PCS
LLO2: distinguish between servo & regulator problems
•LLQ1(on LLO1):
Identify the process variables involved in STH system and infer on the
role of TC, LC & FC in PCS of STH system. (CDLL – U)
LLQ2(on LLO2):
What is the role of servo & regulator problems in process control
applications?
(CDLL – U)