CHEN 4460 – Process Synthesis, Simulation and Optimization Dr. Mario Richard Eden Department of Chemical Engineering Auburn University Lab Lecture No. 5 – Introducing LINGO October 16, 2012 Optimization Software

LINGO –Should be available on computers –If not, download zip file from class webpage –Program is started using C:\LINGO\LINGO.EXE

Optimization Software LINGO –To start entering a new optimization problem type: Model: –Enter the objective function by typing: min = ……;or max = ……; –Then enter the constraints. –Each line must end by a semi-colon ; –The final statement in the problem should be “end”

Optimization Example Hydrogen Sulfide Scrubbing –Two variable grades of MEA. –First grade consists of 80 weight% MEA and 20% weight water. Its cost is 80 cent/kg. –Second grade consists of 68 weight% MEA and 32 weight% water. Its cost is 60 cent/kg. –It is desired to mix the two grades so as to obtain an MEA solution that contains no more than 25 weight% water. –What is the optimal mixing ratio of the two grades which will minimize the cost of MEA solution (per kg)?

Optimization Example Hydrogen Sulfide Scrubbing (Cont’d) –Objective functionmin z = 80  x  x2 –Constraints Water content limitation0.20  x  x2 ≤ 0.25 Overall material balancex1 + x2 =1 Non-negativityx1 ≥ 0 x2 ≥ 0 Variables (Basis 1 kg solution) x1Amount of grade 1 (kg) x2Amount of grade 2 (kg) zCost of 1 kg solution (cents)

Optimization Example Solve using LINGO Press this to solve problem

Optimization Example Solve using LINGO Press this to switch to results