Optimum Operation of In-Plant Cogeneration Systems

Selecting the best way to run large in-plant cogeneration systems to meet site electricity and steam demands at minimum cost is a highly complex problem. With typical annual fuel bills of several tens of millions of dollars, even small percentage changes in operating efficiency can have a large cost effect. An advisory system which incorporates a detailed power plant simulation model and a mathematical optimization package can determine the optimum settings for control variables of the power plant and eliminate uncertainties associated with achieving the minimum cost operation. TENSA Services and their parent company, ICI PLC, have developed and applied systems to achieve these optimization objectives. Both on-line and off-line systems have been installed. These systems can solve the optimization problem quickly and in real time, yielding operating costs savings of two to six percent with short paybacks. An overview of these systems is presented. Their application is illustrated by a case study