Design and Control of a Heat-Integrated Reactor /Column Process

The dynamics and control of a heat-integrated reactor/column system were studied. An exothermic reactor was the heat source, and a distillation column reboiler was the heat sink. Indirect and direct heat-integration schemes were studied. In the indirect heat-integration system, the reactor was cooled by generating steam, which was then used as the heating medium for the reboiler. In the direct heat-integration system, the reactor liquid was circulated directly through the distillation column reboiler. The indirect heat-integration system was found to have several advantages over the direct heat-integration system in terms of its dynamic performance. Both systems were operable for both large and small temperature differences between the reactor and the column base. Somewhat unexpectedly, the heat-integration system with a small temperature difference was found to be more controllable than a system with a larger temperature difference. However, the cost of the heat exchanger increased rapidly as the temperature difference decreased. The minimum economic temperature difference appears to be about 60 °F. Changing kinetic parameters, such as the activation energy, did not have a drastic effect on the overall dynamic performance of either the indirect or direct heat-integration systems.