Methods and apparatus for optimizing combined cycle/combined process facilities

Methods (400) and systems (200) for operating combined cycle electrical generating plants (100) is provided. The method includes simulating (402) the electrical power plant performance, simulating (404) the steam utilizing process plant performance, parameterizing (406) plant equipment and plant performance using the power plant and process plant simulation results, and solving (408) parameterized simultaneous equations and constraints with an objective function to determine parameter settings that facilitate enhancing an efficiency of the combined cycle electrical generating/steam-utilizing process plant. The system includes a first process plant that generates a quantity of waste heat, a second process plant that utilizes heat as an input to at least one plant process wherein the second plant is in heat-transfer communication with the first process plant, and a computer operationally coupled to at least one of the first process plant and the second process plant wherein the computer is configured to monitor process parameters, simulate process plant performance, parameterize a plurality of overall plant equipment and overall plant performance, and solve parameterized simultaneous equations and constraints.