A general strategy for the optimum design of heat recovery steam generators

The optimization of the heat recovery steam generator (HRSG) is one of the key elements for increasing the efficiency of combined plants and can Occur at various levels of complexity with objectives sequentially defined. In the paper a general strategy for the optimum design of the HRSG is outlined. The optimization is organized at two levels: the first one enables to obtain the main operating parameters of the HRSG, while the second involves the detailed design of the component and the geometric parameters of the heat exchanger sections. The second level of the optimization is articulated in two different steps. The first step is aimed to the minimization of the pressure drop for a given heat flow. The second step leads to a reduction of the overall dimensions, maintaining the imposed performance of the HRSG in term of heat flux and pressure drop. The whole procedure is tested with reference to a case of existing HRSG structures; it shows the possibility of improving performance maintaining a constrained packaged size.