High temperature heat and water recovery in steam injected gas turbines using an open absorption heat pump

The advantages of reinjecting steam from the heat recovery steam generator (HRSG) in the preceding gas turbine are increased power and electrical efficiency at low specific cost and a high operating flexibility. The discharge of the injected steam to the ambient has however two major drawbacks: (1) a relevant water consumption and (2) a large thermal loss related to the latent heat of steam. An open absorption heat pump cycle (HT-CBT) downstream of the HRSG can solve both problems, as it allows to recover the steam from the flue gas and use its condensation heat at elevated temperature. This paper presents a concept to efficiently integrate both technologies and assesses the potential of the absorption system for a steam injected gas turbine (STIG). Over a wide range of steam injection rates, the power output of the plant can be varied without the associated energetic penalty achieving improvements in the fuel efficiency of up to 26%.