关键词: 隔离壁精馏塔, 蒸馏, 塔器, 黑洞, 进料热状况, 四点控制, 优化设计

Abstract: While four-point control strategy (i.e.，the main compositions of the three products and the ratio between the two impurities in the intermediate product are controlled simultaneously) is used for the dividing-wall distillation column (DWDC)，the black-hole problem occurs and limits process flexibility and operability. In this paper，a philosophy was proposed to eliminate the black-hole problem with careful adjustment of the thermal conditions of feed and intermediate product. Through strong influence on the overall energy balance of the DWDC，these two variables affected the interlinking flows between prefractionator and main distillation column involved and could thus serve to coordinate their relationship. The dynamic responses were also improved after elimination of the black-hole problem. A simple rule was proposed to adjust the thermal conditions and three possible configurations could be obtained. The separation of a hypothetical ternary mixture，A，B，and C simulated with Aspen Plus，was chosen to evaluate the feasibility and effectiveness of the proposed philosophy. After steady-state analysis and closed-loop control studies，the results demonstrated that the black-hole problem could be completely removed through careful adjustment of the thermal conditions of feed and intermediate product. This philosophy brought the method of eliminating the black-hole problem to completion and enhanced the flexibility and operability of the DWDC.

Key words: dividing-wall distillation column, distillation, column, black-hole problem, feed thermal condition, four-point composition control, optimization