The dynamic model of a rectification heat exchanger using the concept of heat-integrated distillation column

Abstract

A dynamic model of the apparatus used for thermal rectification of mixtures was developed, where in a channel-type exchanger the thermal separation of substances is accompanied by diaphragm heat exchange. In the description of the channel-type exchanger applied in heat-integrated distillation columns, a new approach in mathematical modelling was used combining the model of thermal resistance (in the description of the diaphragm heat exchange) and the theoretical tray model (in the description of the mass transfer). In the literature, it wasn't presented yet the influence of industrial constraints (grow up of deposits on the heat transfer surface or hold up of liquid inside the channel of exchanger) on the heat-integrated distillation column behaviour in the dynamic state. Thus, the authors carried out the numerical simulations for the proposed dynamic model subjected to industrial constraints. The transient characteristics, obtained from the simulations, show that the channel-type exchanger is dynamically stable under industrial constraints. Moreover, the dynamic model confirmed that the distillate purity isn't strongly sensitive on the above constraints (the distillate purity deteriorates approximately by 1%). What's more, the transient characteristics show that the commonly used a proportional–integral–derivative controller can be applied in proposed technology under industrial constraints.