Reheat-Air Brayton Combined Cycle Power Conversion Design and Performance Under Nominal Ambient Conditions

Abstract

Modern large air Brayton gas turbines have compression ratios ranging from 15 to 40 resulting in compressor outlet temperatures ranging from 350 °C to 580 °C. Fluoride-salt-cooled, high-temperature reactors, molten salt reactors, and concentrating solar power can deliver heat at temperatures above these outlet temperatures. This article presents an approach to use these low-carbon energy sources with a reheat-air Brayton combined cycle (RACC) power conversion system that would use existing gas turbine technology modified to introduce external air heating and one or more stages of reheat, coupled to a heat recovery steam generator to produce bottoming power or process heat. Injection of fuel downstream of the last reheat stage is shown to enable the flexible production of additional peaking power. This article presents basic configuration options for RACC power conversion, two reference designs based upon existing Alstom and GE gas turbine compressors and performance of the reference designs under nominal ambient conditions. A companion article studies RACC start up, transients, and operation under off-nominal ambient conditions.