The invention concerns a simulated moving bed adsorption separation device comprising a limited number of valves. According to the invention, the device comprises a column with a plurality of sectors Sk with 2 superimposed plates Pi with a single distribution network, each sector Sk comprising an external principal bypass line Lk connected to each plate Pi of Sk via a plate valve V.sub.i. Each line Lk comprises a flow limitation means and is connected to each of the fluid networks via a single valve.Further, the connectors of lines Lk onto the column are offset by at most 20.degree. inside Sk to limit the volume of lines Lk, and are offset by a mean angle in the range 70.degree. to 110.degree. between two neighbouring sectors Sk and Sk+1 so as not to weaken the column mechanically. The plates preferably comprise panels DMEi,j with parallel segments the direction of which varies from plate to plate or per group of 2 plates.The invention also concerns a separation process using said device, in particular to separate para-xylene or meta-xylene from an aromatic C8 cut.