View
34
Download
0
Category
Tags:
Preview:
DESCRIPTION
CBE / MET 433. 15 Feb 12 (Chapter 3: Process Modeling). Models of Process Dynamics Empirical Dynamic Models: can frequently describe process dynamics, but are “data fits” over a specific range of operation. - PowerPoint PPT Presentation
Citation preview
1
CBE / MET 433
15 Feb 12(Chapter 3: Process Modeling)
Models of Process Dynamics• Empirical Dynamic Models: can frequently describe
process dynamics, but are “data fits” over a specific range of operation.
• Theoretical Dynamic Models: are based on theory and might be useful for extrapolating. Also can be useful for determining controller tuning. Accuracy depends upon model details.
2
Process Modeling: Stirred Tank Heater
3
Process Modeling: Stirred Tank Heater
4
5
6
7
8
9
10
Develop Block Diagram
Develop Block Diagram
13
T Sensor
Transducer
.var.var..
inputindeviationoutputindeviationFT
14
Develop System Block DiagramTransmitter
http://www.omega.com/thermocouples.html
TE selection guide
Type T TC
15
Develop System Block DiagramTransmitter
Transducer
16
Develop System Block DiagramTransmitter
Transducer
Valve
17
Develop System Block DiagramTransmitter
Transducer
Valve
Energy Transfer
18
Develop System Block DiagramTransmitter
Transducer
Valve
Energy Transfer Controller
19
Develop System Block DiagramTransmitter
Transducer
Valve
Energy Transfer Controller
Process
20
Feedback Block DiagramTransmitter
Transducer
Valve
Energy Transfer Controller
Process
21
Feedback Block Diagram
11s
11
sK
s+
+
si
sQ
sWVK
sMcK sM y-
sE+ sR
TK sC
sMor T
22
Feedback Block Diagram (simplified)
11s
1
sK
s+
+
si
sWVK
sMcK
-
sE+ sR
TK sC
23
Closed Loop Transfer Function (let R(s)=0)
11s
1
sK
s+
+
si
sWVK
sMcK
-
sE+ sR
TK sC
sKKKsKs
ss TcVi
11
1
TcVi KKK
sKs
ss
11
11
24
Closed Loop Transfer Function (let R(s)=0)
11s
1
sK
s+
+
si
sWVK
sMcK
-
sE+ sR
TK sC
TcV
i KKKsKs
ss
11
11
looptheinblocksallouputtoinputfrompathdirectonblocksall
ss
input
output
1
25
Open Loop vs Closed Loop
Transfer Function (R(s)=0)
11s
1
sK
s
++
si
sWVK
sMcK
-
sE+ sR
TK sC
TcVi KKK
sKs
ss
11
11
Open Loop:
Closed Loop:
11ss
s
i
TcV KKKKs
11
11
11
sKKKK
KKKK
TcV
TcV
1*
*
sK
*
* 1K tt
evse *
t
eAt 1
*1*
teAKt
26
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 1 2 3 4 5
time (t)
Y(t)
Open - loop
Closed - loop
t
time
AK *
A
27
Transfer Functions (Chap 3-5)
11s
1
sK
s
++
si
sWVK
sMcK
-
sE+ sR
TK sC
11
s
GL
Define:
For heated, stirred tank:
..FTG
)()(ss
i
VV KG
1
sKGP
cc KG
TT KG
11s
1
sK
s
++
si
sWVK
sMcK
-
sE+ sR
TK sC
LG
PGVGcG
TG
)()(sRs
28
29
11s
skgsW C
LG sTo
11s
skg
s sW C
sG sTo
11s
CsTi
C
iTG sTo
30
LG
sG sTo+
+
sW
sWsVG
sMcG
-
sE+ sR
TG sC
iTG
sTi
+
sRSPG
sT seto
31
LG
sG sTo+
+
sW
sWsVG
sMcG
-
sE+ sR
TG sC
iTG
sTi
+
)(sWsTo
)(sTsT
i
o
)(sT
sTseto
o
Recommended