| Batch distillation is a common separation technology in chemical industry because of its simple equipments and flexible operation, which is widely used in fine chemical and pharmaceutical industry. In batch distillation, total reflux has the largest separation capacity, regardless of reflux ratio, so it is easy to operate. In order to make advantage of this characteristic, in this paper, we proposes a new mode of operation: constant total reflux batch distillation of dynamic accumulation, characterized by the mid-vessel in which liquid is transferred to the vessel above, in this way, the whole column maintains the state of total reflux.We first establish the mathematical model to verify this new operation, and compare with partial reflux under the same conditions. Simulation results show that by observing time-dependent profiles of top concentration we conclude that the new operation can keep a high top concentration for a long time. Comparing with the partial reflux, the new mode saves up to 15% operating time.In experimental studies, we design the setup of constant total reflux batch distillation of dynamic accumulation with three mid-vessels, applying water / acetic acid to study the new operation. Experiment results show that comparing with partial reflux batch distillation, constant total reflux operation saves about 10% operation time, meanwhile, acquires the highest purity of 85.6% (R = 4, 81.0%; R = 8, 84.7 %). Simulation and experiment prove that constant total reflux batch distillation of dynamic accumulation can obtain products of higher concentration and require shorter operation time. |
