Capabilities of the internal heat recovery for increasing the efficiency of gas turbine power plants

The capabilities of the internal re-utilization of the exhaust thermal energy in gas turbine plants ('internal heat recovery') have been explored in this paper. Different conventional and unconventional techniques, as classical regeneration, steam injection, humid air regeneration and chemical recovery, have been examined through a unified approach, introducing a meaningful characteristics plane of the internal and recovery. Performances comparable to those of the gas-steam combined plants (external recovery) are achievable by the humid air regeneration, applied to simple cycle heavy-duty gas turbines, and by the chemical recovery, when methanol is used as primary fuel, applied to both heavy-duty and aeroderivative gas turbines. Higher efficiencies are conceptually achievable by more complex solutions based on the combined conventional regeneration and chemical recovery