Kaibel divided-wall column (KDWC) permits separation of a four-component mixture into four pure fractions in a divided-wall column. This work studied separation of a four-component mixture of benzene

toluene

o-xylene and tri-methyl-benzene in a KDWC. The optimum economic design of the Kaibel divided-wall column was obtained. Then seventeen cases of various feed compositions were investigated for obtaining the steady state behavior of the KDWC. Xylene should be controlled at the top of the prefractionator

while toluene should be controlled at the bottom of the prefractionator; the content of heavy impurities was much larger than that of the light impurities in the two side streams; the intermediate component

toluene re-mixed in the prefractionator. At last

a control structure with five composition control loops was established. Simulation showed that it could handle ±10% disturbances of flow rate and feed composition

but the purity of xylene sometimes had small deviations.