Yokogawa EJX930A - Manual (Page 111)

A3-16
IM 01C25T02-01E
A3.6 Application Example
The following describes the temperature control system of a fixed bed-type reactor. In this case, there are
instances where the point showing the maximum temperature changes due to catalytic deterioration, raw
material flow, etc. Therefore, a large number of measurement points are provided, and the maximum value
obtained among these measurement points is input to the controller to control reactor temperature.
FA0310.ai
IS
PID
AI3
AI1
AI2
AI4 AO
Refrigerant
Raw material
Product
C
ata
lyti
c r
ea
cto
r
Figure A3.10 Temperature Control System of a Fixed Bed-type Reactor
IS
IN_1 4 OUT
PID
BKCAL_IN
OUT IN
AO
CAS_IN
BKCAL_OUT
AI1
OUT
AI1
OUT
AI
OUT
AI1
OUT
AI1 AI4
FA0311.ai
Figure A3.11 Example of Scheduling
AI1: Temperature 1, AI2: Temperature 2, AI3: Temperature 3, AI4: Temperature 4
IS: SELECT_TYPE = MAX
Basic operations and work sequence:
1. The IS block obtains values and status information from AI.
2. The block selects the AI information using the alternatives.
3. The block displays and outputs the information selected by SELECTED.