Method for controlling dividing-wall distillation column

Abstract

The invention discloses a method for controlling a dividing-wall distillation column. The method adopts four control loops, namely, an overhead distillate composition control loop which controls overhead reflux through overhead distillate component concentration; a siding distillate composition control loop which controls siding reflux through sliding distillate component concentration; a column bottom distillate composition control loop which controls column bottom thermal load through column bottom distillate component concentration; and a pre-distillation section top gas-phase composition control loop which controls a fractional liquid ratio of the interior of the dividing-wall distillation column through pre-distillation section top gas-phase component concentration. All the control loops are preferably a PID (proportion-integration-differentiation) control loop. The control method disclosed by the invention can realize stable control of the entire column when feeding flux or feeding component concentration changes, and further ensure the produce quality and ensure the energy consumption of the entire column to be within an optimum range.

Description

technical field [0001] The invention belongs to the field of chemical distillation process and automatic control, and relates to a control method for separating multi-component mixtures in a dividing wall rectification tower. Background technique [0002] With the increasingly tense energy sources and increasingly fierce market competition, energy conservation and consumption reduction have received more and more attention in the operation and management of the chemical industry. As a typical process intensification technology, the dividing wall distillation column has been widely concerned by the industry and researchers. [0003] Dividing wall distillation columns provide clean division of three-, four-, and higher-component mixtures within a single column. The dividing wall rectification column is a vertical partition wall installed inside the rectification column, which divides the rectification column into four parts: the upper and lower parts of the partit...

AI Technical Summary

Problems solved by technology

The four-point control model increases the use of the purity of the top and bottom products to adjust the impurity content of the side product. This model cannot ensure that the dividing wall distillation column operates near the optimal energy consumption, and cannot be used when the feed flow rate and feed composition fluctuate. Achieve smooth control

Although their conclusions show that MPC works better, the assumption that the heat input is fixed in the PID control model calls into question the correctness of their conclusions

Also, the selection of other variable groups and improved control adjustments are not evaluated in their paper

[0008] In the above few studies, although the research on the control of raw material composition and raw material flow fluctuations has been carried out, the problem of how to achieve stable control of the dividing wall distillation column and maintain the purity of the product has not been resolved when the raw material composition fluctuates on a large scale

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