Optimal efficiency as a design criterion for closed loop combined cycle industrial cogeneration

In comparison to conventional industrial cogeneration plants, the closed loop combined cycle cogeneration (CLCC) system has the advantage that it needs virtually no enhancement in steam handling capability of the existing plant, both in terms of steam pressure as well as volume flow rates. An optimal design procedure is introduced in this paper for the configuration of a CLCC system between existing steam headers of an industrial setup. While aiming primarily at maximization of generation efficiency for the CLCC configuration, the design approach simultaneously attempts to configure a suboptimal number of units for each item of cogeneration equipment. The suboptimal (integer) number of units is maintained within a specified suboptimal margin of the corresponding optimal (real) number of units that emerges from efficiency maximization. The design procedure relies heavily on a database including all available makes of cogeneration equipment. Consequently, the approach is very much market dependent, as illustrated adequately by a suitable case study.