Heat Recovery Design Considerations for Cogeneration Systems

The design and integration of the heat recovery section, which includes the steam generation, auxiliary firing, and steam turbine modules, is critical to the overall performance and economics of cogeneration, systems. In gas turbine topping cogeneration systems, over two-thirds of the energy is in the exhaust gases leaving the gas turbine. In bottoming cycles, where steam and/or electrical power are generated from heating process exhaust streams, the heat recovery design is of primary concern. John Zink Company, since 1929, has specialized in the development, design, and fabrication of energy efficient equipment for the industrial and commercial markets. The paper outlines the design, installation and performance of recently supplied gas turbine cogeneration heat recovery systems. It also describes; several bottoming cycle thermal system designs applied to incinerators, process heaters, refinery secondary reformers and FCC units. Overall parameters and general trends in the design and application of cogeneration thermal systems are presented. New equipment and system designs to reduce pollution and increase overall system efficiency are also reviewed