Fun unda dame ment nta als of Dist istil illa lati tion on Colu Column mn Cont Control rol by Terry Tolliver Standards Certification Education & Training Publishing Conferences & Exhibits
ISA Automation Week 2011
PRES PR ESEN ENTE TER R – Te Terr rry y Tol Tolliliver ver
•
Terry is a retired Senior Fellow from Solutia/Monsanto Solutia/Monsanto and presently provides contract engineering at ConocoPhillips Wood River refinery. He has 40+ years of experience in process control, simulation, operations, troubleshooting and optimization.
•
Terry graduated from the Missouri University of Science and Technology with BS, MS & PhD ChE and was recently inducted into their Academy Academy of Chemical Engineers in 2009. He was inducted into into the CONTROL Automation Hall of Fame in 2002.
•
He has received several ISA awards including the Distinguished Society Service Award in 1997, the E. G. Baily Award in 1993 and the Excellence in Documentation award in 1987.
•
Terry has been an adjunct professor for Washington University from 2004-2008, a Lehigh University Biannual Lecturer from 1974-1986, an ISA Fellow in 1990, an AIChE Fellow in 2000 and a PE since 1974.
PRES PR ESEN ENTE TER R – Te Terr rry y Tol Tolliliver ver
•
Terry is a retired Senior Fellow from Solutia/Monsanto Solutia/Monsanto and presently provides contract engineering at ConocoPhillips Wood River refinery. He has 40+ years of experience in process control, simulation, operations, troubleshooting and optimization.
•
Terry graduated from the Missouri University of Science and Technology with BS, MS & PhD ChE and was recently inducted into their Academy Academy of Chemical Engineers in 2009. He was inducted into into the CONTROL Automation Hall of Fame in 2002.
•
He has received several ISA awards including the Distinguished Society Service Award in 1997, the E. G. Baily Award in 1993 and the Excellence in Documentation award in 1987.
•
Terry has been an adjunct professor for Washington University from 2004-2008, a Lehigh University Biannual Lecturer from 1974-1986, an ISA Fellow in 1990, an AIChE Fellow in 2000 and a PE since 1974.
DISTIL DIST ILL L A TION CONTRO CONTROL L TOPI TOPICS CS
• Levels of control • Classification and pairing of variables • Control objectives and constraints • Dynamic responses • Material and energy balances • Separation • Pressure control • Material balance control • Temperature control • References
DISTILLATION CONTROL
BASIC Inventory Control
–
Composition Control
–
SUBOPTIMIZING Feedforward Control
–
Two Point Composition Control
–
OPTIMIZING Floating Pressure
–
Maximum Profit
–
CLASSIFICATION and PAIRING of VARIABLES
CONTROLLED VARIABLES distillate composition bottom composition accumulator level sump level column pressure
P La Y
Y
X La Ls P
Ls
X
CLASSIFICATION and PAIRING of VARIABLES
MANIPULATED VARIABLES distillate flow bottom flow reflux flow reboiler duty condenser duty
Q c
D B
R
D
R Q r Q c Q r
B
CLASSIFICATION and PAIRING of VARIABLES
DISTURBANCE VARIABLES feed flow feed composition feed temperature reboiler heat supply condenser cooling supply and weather
W F Z q
F Z q
S W
S
CLASSIFICATION and PAIRING of VARIABLES
CONTROLLED VARIABLES
MANIPULATED VARIABLES
DISTURBANCE VARIABLES
distillate composition bottom composition accumulator level sump level column pressure
distillate flow bottom flow reflux flow reboiler duty condenser duty
feed flow feed composition feed temperature reboiler heat supply condenser cooling supply and weather
CONTROL OBJECTIVES
Total Operating Cost
$/F
Cost of Energy
Cost of Product Lost
RECOVERY
COLUMN CONSTRAINTS
Reboiler Flood Condenser
e t a r p u l i o B
Weep
Vessel Limit
Column Pressure
COLUMN INTERNALS
TRAYS – – – –
SIEVE TRAYS VALVE TRAYS BUBBLE CAP TRAYS DUAL FLOW TRAYS
PACKING – RANDOM PACKING – STRUCTURED PACKING – LIQUID & VAPOR DISTRIBUTORS
COLUMN DYNAMICS
RELATIVE RESPONSE TIMES VAPOR - FAST LIQUID - MEDIUM COMPOSITION - SLOW Response
time
MATERIAL & ENERGY BALANCES
MATERIAL BALANCE F = D+ B zF = yD + xB
D/F = (z-x)/(y-x)
ENERGY BALANCE hF + Qreb = hD + hB + Qcond
SEPARATION
TOTAL REFLUX n
= [y(1-x)]/ [x(1-y)]
NORMAL OPERATION S =f ( , N, NF, V/ F, z, E)
MATERIAL BALANCE and SEPARATION EFFECTS
1.0
y
Increasing S n o i t c a r F e l o M y e K t h g i L
Z
X Increasing S
0 0
D/F
1.0
MATERIAL BALANCE CONTROL
FC
FC LC
FC TC
FC LC FC
SEPARATION CONTROL
FC
FC LC
FC TC
NO T REC O M M EN DED
FC LC FC
PRESSURE CONTROL
VENT
PI
FC
FC LC
CONDENSER DUTY
Tp Qcond = UA(Tp-Tc ) COOLANT
Tc
VENT
CONDENSATE
“ BLOCK & BLEED” PRESSURE CONTROL
INERTS E V L A V D E E L B
VACUUM SOURCE BLOCK VALVE
PC
FC
FC LC
MATERIAL BALANCE CONTROL - TYPE 1
FC
FC LC
FC TC
FC LC FC
MATERIAL BALANCE CONTROL - TYPE 2
FC
FC
LC
FC TC
FC LC FC
MATERIAL BALANCE CONTROL - TYPE 3
FC
FC
LC
FC TC
FC LC FC
MATERIAL BALANCE CONTROL - TYPE 4
FC
FC
LC
FC TC
response
FC LC FC
time
PROCESS SIMULATION
STEADY STATE • • • •
PARAMETRIC CASES CONTROL STAGE LOCATION SENSITIVITY ANALYSIS DISTURBANCE ANALYSIS
DYNAMIC • •
STUDY CONTROL RESPONSE STARTUP AND SHUTDOWN
CONTROL STAGE LOCATION
Benzene-Toluene Column Temperature Profiles 18 17 16 15 14 13 12 11
r e b 10 m u N 9 e g a 8 t S
+1%D/F
7 6 5
-1%D/F
4 3 2 1 0 70.0
75.0
80.0
85.0
90.0
95.0
100.0
Temperature, DegC
105.0
110.0
115.0
120.0
TEMPERATURE SENSITIVITY
DISTILLATE PRODUCT
% t w , N O I T I S O P M O C
BOTTOM PRODUCT
CONTROL STAGE TEMPERATURE, degF
DISTURBANCE ANALYSIS
Benzene-Toluene Column Load Effects 17 16 15 14 13 12 11 10
r e b m u N y a r T
9 8 7 6 5 4 3 2 1 0 -5.0
-4.0
-3.0
-2.0
-1.0
0.0
Delta Tem per atur e, DegC
1.0
2.0
3.0
REFERENCES
