Temperature control of a Kaibel, Agrawal and Sargent dividing-wall distillation columns

Abstract

Intensified multi-partition dividing wall distillation columns (DWCs) have attracted the attention of academy and industry as they present benefits in the capital and operating costs over traditional and single-partition distillations systems. This work investigates and compares the economic and dynamic performance of commonly used four-product DWCs, i.e., Kaibel, Agrawal, and Sargent columns, to separate an industrially relevant mixture of benzene, toluene, xylene, and heavies. Optimal economic designs were obtained considering product specifications and compared in terms of the total annual cost (TAC). Remarkably, the Sargent column requires 45 and 28 % less energy requirements compared with the Agrawal and Kaibel columns, respectively, which translated into significant TAC savings. A dynamic study is also presented, considering conventional and differential temperature control schemes. The three systems' controllability is adequate as the proposed differential temperature control schemes allowed obtaining stable product specifications, close to their design values after the considered feed and composition disturbances. Also, the single and multi-partition DWCs can effectively handle disturbances without using vapor splits as manipulated inputs.