# CBE 491 /433 - PowerPoint PPT Presentation

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15 Oct 12 Model of Stirred Tank Heater. CBE 491 /433. Goal: set up models to simulate and see effect of tuning parameters 1 st principles (Chaps 3 – 6); transfer functions (just looked at this a bit) process simulators ( AspenPlus Dynamics; CBE 450/550 class).

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CBE 491 /433

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#### Presentation Transcript

15 Oct 12

Model of Stirred Tank Heater

CBE 491 /433

• Goal: set up models to simulate and see effect of tuning parameters

• 1st principles (Chaps 3 – 6);

• transfer functions (just looked at this a bit)

• process simulators (AspenPlus Dynamics; CBE 450/550 class)

Stirred Tank Heater (w/ PI Controller)

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energy balance on tank w/o control

PI controller equation

Stirred Tank Heater (w/ PI Controller)

Let:

ODE Solver (POLYMATH; MATLAB; MATHCAD; etc)

Polymath code:

step= if (t<1) then (0) else (1)

Ti = 0 + step * 10

ODE Solver: POLYMATH

Polymath code (stirred tank heater):

d(C) / d(t) = -1/tau*C + KT/tau*Ti + K1KT/tau*M

C(0) = 0

d(errsum) / d(t) = R – C

errsum(0) = 0

tau = 5 # min

KT = 0.5 # %TO/degC

K1KT = 0.8 # %TO/%CO

R = 0 # set point stays same

M = Kc*(R-C) + Kc/tauI*errsum

step = if (t<1) then (0) else (1)

Ti = 0 + step * 10 # step change disturbance

Kc = 1.3 # %CO/%TO

tauI = 10 # min

t(0) = 0

t(f) = 100 # min

• In Class Demo / Exercise:

• Polymath Demonstration

• Build model in Polymath (ODE solver)

• Solve; graph C vs t

• Explore:

• Try P-only controller

• Try different Kc/tauI sets

• Can you get underdamped response?

• What is response to step change in R(t); holding Ti at the SS value?

Model of Stirred Tank Heater

CBE 491 / 433

• Goal: set up models to simulate and see effect of tuning parameters

• 1st principles (Chaps 3 – 6);

• transfer functions (just looked at this a bit)

• process simulators (AspenPlus Dynamics; CBE 450/550 class)

Stirred Tank Heater (transfer function simulator)

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Transfer function simulator: Loop Pro Developer (Control Station)

• In Class Demo / Exercise:

• Build model in Loop Pro Developer (Custom Process)

• Turn on PI Controller and set Kc and tauI

• Explore:

• Change load (Ti) up by 10 to 60%; observe system response

• Change back to 50%; observe response

• Try P-only controller

• Try different Kc/tauI settings

• Can you get underdamped response?

• What is response to step change in R(t) to 60%?

Model of Stirred Tank Heater

CBE 491 / 433

• Goal: set up models to simulate and see effect of tuning parameters

• 1st principles (Chaps 3 – 6);

• transfer functions (just looked at this a bit)

• process simulators (AspenPlus Dynamics; CBE 450/550 class)

SAVE your Polymath and Loop Pro Developer Models !!