Optimization of operating temperature for continuous glucose isomerase reactor system

Abstract

The optimal temperature control policy for an immobilized glucose isomerase reactor system was studied. This optimization study takes into consideration the enzyme deactivation during the continuous reactor operation. The kinetic parameters including reduced Michaelis-Menten constant (i?,,,), reduced maximum reaction rate (V,,,), equilibrium constant (&), and enzyme deactivation constant ( k d ) and their functional relationships to temperature were determined experimentally. The optimization problem was formulated in terms of maximization of fructose productivity as the objective function. The optimization problem was solved by making use of a maximum principle and the control vector iteration method. Approximately 8% improvement in terms of fructose productivity was achieved when the preprogrammed optimal temperature control policy was employed as compared with the reactor operation at an optimum constant temperature.

Optimal temperature policy for immobilized enzyme packed bed reactor performing reversible Michaelis–Menten kinetics using the disjoint policy

“…However, one limitation of this control variable is the narrow range within which enzymes remain active (Lee, 1992). In spite of this, many researchers have used two types of temperature operating policies utilizing the enzymatic isomerization of glucose to fructose as a model system (Abu-Reesh and Faqir, 1996;Faqir, 1998;Hass et al, 1974;Kim et al, 1982;Park et al, 1981;Straatsma et al, 1983). These operating policies are either a rising temperature policy with time to maintain a constant outlet conversion or a constant temperature pro®le that maximizes the average reactor productivity.…”

“…Most of the published works on determining the optimum temperature operating policy for continuous packed bed reactors performing reversible Michaelis±Menten kinetics use either Pontryagin's maximum principle or nonlinear programming methods (Faqir, 1998;Haas et al, 1974;Kim et al, 1982;Park et al, 1981;Straatsma et al, 1983;Vos and Luyben, 1993). The main disadvantages of these optimization methods are the tedious formulation and complex solution algorithms used to obtain the desired solution.…”

“…The ®rst one is the control of feed rate to the reactor in such a way that it decreases as function of time in order to compensate for the loss of enzyme activity. The second mode is the temperature and/or pH pro®le that is set according to a well-de®ned time pro®le (Faqir, 1998;Haas et al, 1974;Kim et al, 1982;Park et al, 1981;Straatsma et al, 1983;Vos and Luyben, 1993). Temperature is one of the most important variables due to its eect on the kinetic parameters, enzyme activity, and substrate protection factor.…”

“…These operating policies are either a rising temperature policy with time to maintain a constant outlet conversion or a constant temperature pro®le that maximizes the average reactor productivity. Park et al, (1981) studied the temperature control policy for the enzymatic isomerization of glucose to fructose using immobilized glucose isomerase in a continuous packed bed reactor. They found that the average productivity is improved by approximately 8% upon using the optimal increasing temperature policy of operation as compared to the optimum isothermal operation.…”

Optimal control policy for substrate inhibited kinetics with enzyme deactivation in an isothermal CSTR

“…Thus, it is possible to cease operation when the enzyme activity falls below a low level or to add fresh enzyme to make up for the activity loss (Verhoff and Schlager, 1981), or, one can manipulate the temperature or the pH of the reactor to achieve an overall optimal operation (Chou et al, 1967;Szepe and Levenspiel, 1968;Ogunge and Ray, 1971;Haas et al, 1974;Sadana, 1979;Park et a]., 1981). Although they produced definite improvements over the uncontrolled case, the above control schemes have various disadvantages.…”