An ODDISAY System: Process Design Optimization by Using MCD Algorithm Alam Nawaz, Moonyong Lee* Process Systems Design and Control (PSDC) Laboratory School of Chemical Engineering, Yeungnam University 214-1 Dae-dong, Gyeongsan 712-749, South Korea *corresponding author email: mynlee@ynu.ac.kr Motivation: The increase in computational capabilities has evolved optimization methodology & have a great impact on the application for the industrial use. Modified Coordinate Decent (MCD) methodology is presented in the ODDISAY system to process optimization problems. The MCD algorithm is coded in Visual Basic and exploited for optimization of two process design problems developed in the Aspen HysysTM simulator. This algorithm converges fast, easy handling of control parameters besides the simple implementation. In NG refrigeration process, high refrigerant flow rate and high overall system pressure are the physical cause of intensive energy requirement in base cases that were successfully reduced by the ODDISAY system. MCD Optimization Algorithm Knowledge Inspired Hybrid MCD Algorithm KSMR : One variable change feasible area change Avoid The Local Optimum Objective function : total compressor duty Optimizing variable : pressure of compressor feed Optimizing variable : flow rate of refrigerant feed Constraints : minimum temperature approach as 3’C Target minimize energy requirement ! KSMR Process Variables For Optimization Oddisay Program Composite Curve of Optimization Result The modification in coordinate decent methodology is made to solve the optimization problem encountered in NG liquefaction cycle. The box space search and sequential randomization of individual coordinate during search are the main modifications to the conventional coordinate decent methodology that give improved convergence performance. This work shows that it save the 30% of the compressor duty (minimize the total energy).