Abstract
Three layer control structure is proposed for optimal control of continuous fermentation processes. The start-up optimization problems are solved as a first step for optimization layer building. A steady state optimization problem is solved by a decomposition method using prediction principle. A discrete minimum time optimal control problem with state delay is formulated and a decomposition method, based on an augmented Lagrange's function is proposed to solve it. The problem is decomposed in time domain by a new coordinating vector. The obtained algorithms are used for minimum time optimal control calculation of Baker's Yeast fermentation process.
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Abbreviations
- x(t) g/l:
-
biomass concentration
- s(t) g/l:
-
limiting substrate concentration
- x 0 g/l:
-
inlet biomass concentration
- s 0(t) g/l:
-
inlet substrate concentration
- D(t) h−1 :
-
dilution rate
- μ(t) h−1 :
-
specific growth rate
- Y g/g:
-
yield coefficient
- ɛ(t) h−1 :
-
specific limiting substrate consumption rate
- k D h−1 :
-
disappearing constant
- w 1, w 2 :
-
known constant or piece-wise disturbances
- μ m h−1 :
-
maximum specific growth rate
- k s g/l:
-
Michaelis-Menten's parameter
- τ h:
-
time delay
- x 0, s 0 g/l:
-
initial concentrations
- ¯x, ¯s, ¯D :
-
optimal steady state value
- V min , V max , v=x,s,d,Δt :
-
bounds of variables
- Δt h:
-
sampling period
- K :
-
number of steps in the optimization horison
- Js, J d :
-
performance indexes
- L s :
-
Lagrange's function
- L d :
-
Lagrange's functional
- λ 0 :
-
weighting coefficient for the amount of the limiting substrate throwing out of the fermentor
- λ 1, λ2 :
-
dual variables of Lagrange's function
- \(\alpha _s^1 ,{\text{ }}\alpha _{\lambda _1 }^1 ,{\text{ }}\alpha _{\lambda _2 }^1 \) :
-
steps in steady state coordination procedure
- \(\varepsilon _s ,{\text{ }}\varepsilon _{\lambda _1 } ,{\text{ }}\varepsilon _{\lambda _2 } \) :
-
errors values for steady state coordination process
- λ v , v=x, s :
-
conjugate variables of Lagrange's functional
- μ v , v=x,s :
-
penalty coefficients of augmented Lagrange's functional
- ϱ v , v=x, s :
-
interconnections of the time
- e v , v=x,s, D, λ x , λ s :
-
gradients of Lagrange's functional
- j, l :
-
indexes of calculation procedures
- ɛ :
-
values of errors in calculations
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The researches was supported by National Scientific Research Foundation under grants No NITN428/94 and No NITN440/94
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Tsoneva, R.G., Patarinska, T.D. Optimal control of continuous fermentation processes. Bioprocess Engineering 13, 189–196 (1995). https://doi.org/10.1007/BF00367253
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DOI: https://doi.org/10.1007/BF00367253