472519 Study on the Distillation Sequence with Dividing Wall Column

Tuesday, November 15, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Zengzhi Du1, Jianhong Wang1, Chi Zhai1, Yunlu Zhang1, Zhexi Zhu1 and Wei Sun2, (1)College of Chemical Engineering, Beijing University of Chemical Technology, Beijng, China, (2)College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, China

Study on the Distillation Sequence with Dividing Wall Column

Zengzhi Dua, Jianhong Wanga, Chi Zhaia, Yunlu Zhanga, Zhexi Zhua, Wei Suna*,

a China Beijing Key Lab of Membrane Science and Technology, College of Chemical Engineering, Beijing University of Chemical Technology, 100029 Beijing, China

Abstract

As an important separation unit, distillation column is widely applied in petrochemical and other process industry. It is reported that there are over 40,000 distillation columns all over the world1. Despite its flexibility and widespread use, one important concern is its considerable energy consumption, as distillation can account for more than 50% of plant operating cost. Therefore a large number of researchers have been concentrated on energy-efficient distillations. For the separation of multi-component mixtures, distillation sequence is required in industry. Dividing wall column (DWC), as a thermally coupled distillation column, has been proposed and applied in distillation sequence2. It is an atypical distillation column with an internal, vertical partition wall, which effectively accommodates two conventional distillation columns into one shell, for separating a multi-component feed mixture into pure products. For three components separation process, there are two columns, two condensers and two reboilers in conventional distillation sequence, while only one DWC with a condenser and a reboiler can be achieved. Compared with conventional distillation column, about 30% energy and equipment investment cost can be saved by DWC3. Until now, it is reported that the number of applications of DWCs have exceeded 1004.

Distillation sequence has been well studied based on simple column series, by which an overall optimization at both process and equipment levels can be achieved. A distillation sequence with DWC will give more number of feasible sequences, which will increase computation load significantly. DWC may not be the best choice for all three component mixture separations in terms of its physical properties and feed composition. It will be more efficient to eliminate distillation sequences with unnecessary DWC.

In this paper, the influence of mixture and its component compositions on the operation of DWC is systematically investigated based on the simulation implemented by gPROMS on different mixture systems. The unnecessary DWC can be eliminated from distillation sequences. Then, the optimal distillation sequence with DWC can be efficiently identified.

Key Words: Dividing wall column; Distillation sequence; Simulation

Reference:

1. Kiss, A. A., Design, Control and Economics of Distillation. In Advanced Distillation Technologies, John Wiley & Sons, Ltd: 2013, 37-65.

2. Wright, RO., Fractionation apparatus, United States patent, US 2471134, 1949.

3. Triantafyllou, C., Smith, R., The design and optimisation of fully thermally coupled distillation columns: Process design, Chemical Engineering Research & Design, 1992, 70, 118-132.

4. Asprion, N.; Kaibel, G., Dividing wall columns: Fundamentals and recent advances. Chemical Engineering and Processing: Process Intensification, 2010, 49 (2), 139-146.


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