Adaptive Robust Generic Model Control of High‐Purity Internal Thermally Coupled Distillation Column

Abstract

The internal thermally coupled distillation column (ITCDIC) is a frontier in energy-saving distillation research. The process inside a high-purity ITCDIC is of great nonlinear dynamics, which trouble the conventional control schemes. A multivariable adaptive robust generic model control (ARGMC) is presented to solve the difficulties, where an ARX model is derived and a recursive least squares estimation (RLSE) method is introduced. The benzene/toluene system is studied as an illustrative example. The results of ARGMC are compared with the robust generic model control (RGMC) and traditional PID control in detail. The performances in both servo control and regulatory control confirm the accuracy and validity of ARGMC for the high-purity ITCDIC process.

Nonlinear-wave based analysis and modeling of heat integrated distillation column

“…The terminal concentrations by wave model, namelyŶ t 1 , andX t n are very close to the actual final concentrations of Y t 1 , and X t n which confirms the validity of the simplified wave model. For the same section of the column, for example, the rectifying section (stages [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], the moving distances of the profiles are quite different when Z f increases and decreases 2%, respectively. When Z f increases 2%, the moving distance is shorter (20.98-18.72, got from Table 3), which makes the deviation relatively small; On the contrary, when Z f decreases 2% the moving distance is longer (18.72-12.88) and it leads to a larger deviation.…”

“…There are two aspects that determine the whole process: the moving distances of the profiles depicted by the movement of the inflection points of S 1 and S 2 , and the wave velocities described by Eqs. (13) and (14). Different positions of the inflection points represent different steady states, and the wave velocities describe how the wave profiles move between different steady states.…”

“…According to Eqs. (11)- (14), the nonlinear wave model can be built. More detailed information could be found in our previous work [36].…”

“…A variety of methods have between developed to improve the energy efficiency of distillation columns, among which the heat integrated distillation technology has attracted a large number of researchers since it was proposed by Mah and coworkers in the form of secondary reflux and vaporization (SRV) [2][3][4][5][6][7][8][9][10]. Many follow-up studies have been carried out and its superiority in energy efficiency over conventional distillation has been proved [7,[11][12][13][14][15][16][17][18][19].…”

“…Once the operating conditions change, the structures and the parameters of the linear models would be invalid. A data-driven model would encounter plant/model mismatch inevitably especially in a high-purity HIDiC on account of the complex dynamics [4,14,25,26]. Process flow simulation by commercial software is accurate but not flexible for the design of online algorithm and control scheme.…”