Chemical process optimization method

A method for producing at least two products from a production site to satisfy a given product demand for each of said products within a fixed time horizon in which the rate of product production required to satisfy such demand is correlated to energy consumption and varied in accordance with a predetermined schedule of production to minimize the cost of electrical energy consumed at said site, with the cost of such energy dependent upon a cost structure having multiple costs levels and wherein said predetermine schedule of production is formulated to correspond to a number of energy cost levels;

• comprising the steps of:
• formulating a process model for said production site which characterizes the operating characteristics of the production site as a functional relationship between the rate of production of each of said products from said site, including any hiatus in the production of such products, and the amount of energy consumed in the manufacture of each of said products over said time horizon with said functional relationship defining a linear or convex relationship;
• identifying the process constraints in the operating characteristics of the production site which determine the limitations and boundaries in the production of said products;
• selecting operating points which satisfy the process model without violating said process constraints;
• limiting the selection of said operating points to a matrix of discrete operating points which identify the feasible operating space of the process;
• computing any feasible operating point within the operating space as a convex combination of fractions of the operating points in the matrix of discrete operating points with each fraction representing a numerical value from zero to one inclusive;
• establishing an objective function which will minimize the cost of energy for the production of said products for all feasible operating points within the defined operating space;
• formulating a linear programming model based upon said objective function the solution of which will determine the minimum rate of energy use required to produce said products for any given process output level within said fixed time horizon;
• solving said linear programming model;
• and operating the said production site to produce the said products based on the solution of said linear programming model.