where f denotes an objective and s k , k ∈ S eq and s l , l ∈ S ineq denote further constraints on the process such as purity specifications. A solution of the optimization problem satisfies all MESH equations, all specifications and minimizes the objective. We start with an initial guess for the variables x opt (Step 0) and calculate all process variables (Step 1). Using all process variables, the remaining MESH equations, the specifications and the objective function can be evaluated (Step 2).Based on their values the optimizer will suggest new optimization variables (Step 3). As the process variables depend on the optimization variables, the map given in Equation ( ) has to be evaluated again (Step 1). This is repeated until all constraints are satisfied and optimality is reached. The steps of the algorithm can be summarized as follows: