Abstract: The maximum concentration of a middle component in a multi-component separation cascade is usually located in the middle of the cascade. Most separation cascades have their product and waste withdrawals at the two ends. The paper presents the results of a numerical study on obtaining higher concentration of a middle component in the product through an additional withdrawal flow in the middle of a square cascade while keeping usual withdrawals at the two ends. Parameters were first analyzed individually to estimate their bounds and to study their influences on the concentration of the target component. Based on the numerical simulation and optimization, a cascade with higher product concentration in the additional middle withdrawal was obtained with the original feed and product flow rates unchanged.