This paper considers the selection of controlled variables for the unconstrained degrees of freedom, such that near-optimal operation is achieved with constant setpoints (“self-optimizing control”).… (More)

The “Petlyuk” or “dividing-wall” or “fully thermally coupled” distillation column is an interesting alternative to the conventional cascaded binary columns for separation of multi-component mixtures.… (More)

We show that the minimum energy requirement for separation of a multicomponent mixture in a three-product Petlyuk arrangement is equal to the minimum energy for the most difficult of the two… (More)

We consider separation of ideal multicomponent mixtures with constant relative volatilities and constant molar flows and at constant pressure. The exact analytical solution of minimum energy in a… (More)

In operation of a large LNG processing plant there will be uncertainties related to planning and realization of an optimal operation strategy. Results show the importance of including the whole… (More)

We address the problem of optimizing operation of a process where there are extra degrees of freedom, and where the optimum is not at some constraint. In practice, there are always unknown… (More)

For a four-component feed, Kaibel (1987) proposed a single dividing wall column (DWC) with two side-streams. We will show that an analytic minimal energy expression for the Kaibel-arrangement is… (More)

A simple and new procedure has been developed for the PI controller tuning of an unidentified process using closed-loop responses. The method requires only one step test in the closed-loop system to… (More)

The proposed method is similar to the Ziegler-Nichols (1942) tuning method, but it is faster to use and does not require the system to approach instability with sustained oscillations. The method… (More)

The Vmin diagram is introduced to effectively visualize how the minimum energy consumption is related to the feed-component distribution for all possible operating points in a two-product… (More)