Design of intermediate heat exchanger for the HTGR-closed cycle gas turbine power generation system

High thermal efficiency can be achieved in a power generation system, which couples a high-temperature gas-cooled reactor(HTGR) with a closed cycle gas turbine(GT). There are three possible systems such as a direct cycle(DC), an indirect cycle(IDC) and an indirect gas-steam combined cycle(IDCC). An intermediate heat exchanger(IHX) is needed in the IDC or in the IDCC. However, the size of IHX is too large for a reasonable design and it has become one of the most important issues. Then, a design has been undertaken based on the experience of the IHX in the HTTR though as a material of heat transfer tubes, a Ni-Cr-W superalloy with the highest strength at temperature was adopted instead of Hastelloy XR used in the HTTR. First, by parametric design studies, the optimum design parameters have been examined for a heat duty of 150 MW. Then, the IHX of 315 MW has been designed specifically and its dimensions and structures were determined. The IHX was clarified to be capable of fabrication at least in the case of IDCC. The results of parametric studies are useful to make a rough estimate for the other cases and some examples are shown. (author)