Patent ID: 8481798
Filing Date: 2013-07-09
Classification: B01D,C07C

Abstract:
1. A process comprising separating a solute from a stream whose composition contains at least the solutes paraxylene (PX), orthoxylene (OX), metaxylene (MX), and ethylbenzene (EB), using a simulated moving bed comprising plural beds and having multiple input and output streams each with individual flow rates, a step time, multiple valve positions, and a pumparound and/or pusharound stream, said process including control of a value of a characteristic of said pumparound and/or pusharound stream, VPAc, to a desired value VPAf using model based control with predictive feedforward, controlling the characteristic value VRc of the recovery of the solute to a desired value VRf, using model based control with predictive feedforward, controlling the characteristic value VPc of the product purity to a desired value VPf, using model based control with predictive feedforward control, said process comprising the steps of at least one of (I), (II) and (III), including substep routines (a) through (d), (e) through (h), and (i) through (l), respectively: (I) (a) determining VPAc from information including at least one of on-line sampling and in-line sampling of the current concentrations of at least one of said solutes in said pumparound and/or pusharound streams at a specific time after a valve position change for at least one valve position within said one or more valve cycles; then (I) (b) comparing VPAc and VPAf; and (I) (c) adjusting at least one parameter selected from the step time and the flow rates of at least one stream in the process, according to a pre-determined model based algorithm, said algorithm relating a change in the current value of the characteristic to changes in said at least one parameter and VPAf; then after at least one step (a), step (b) and step (c), (I) (d) repeating at least one step (a), step (b), and step (c); and (II) (e) determining VRc from information including at least one of on-line sampling, in-line sampling, and at least one flow meter, of the current concentrations of at least one of said solutes in at least one stream in the process; then (II) (f) comparing VRc and VRf; then (II) (g) adjusting at least one parameter selected from the step time and the flow rates of at least one stream in the process, according to a predetermined algorithm, said algorithm relating a change in the current value of the characteristic to changes in said at least one parameter and VRf; then after at least one step (e), (f) and (g), (II) (h) repeating at least one step (e), step (f) and step (g); and (III) (i) determining VPc from including at least one of on-line sampling, in-line sampling, and offline sampling, of the current concentrations of at least one of said solutes in at least one stream in the process; then (III) (j) comparing VPc and VPf; then (III) (k) adjusting at least one parameter selected from VPAf, the step time, and the flow rates of at least one stream in the process, according to an algorithm, said algorithm relating a change in the current value of the characteristic to changes in said at least one parameter and VPf; then (III) (l) repeating at least one step (i), (j), (k).