Abstract: A combined cycle power plant comprises a gas turbine engine comprising a compressor to produce compressed gas, a combustor to produce combustion gas from compressed gas and fuel, and a turbine to receive combustion gas to produce rotational shaft power; a steam system generates steam from water using the combustion gas exiting the turbine; a first stage fuel-gas heater receives the fuel before entering the combustor and receive feedwater from the steam system to transfer heat from the feedwater to the fuel; and a second stage fuel-gas heater receives at least a portion of the fuel from the first stage fuel-gas heater to transfer heat to the fuel from a heat transfer medium before the fuel enters the combustor. A method comprises operating a gas turbine engine, operating a steam cycle, extracting compressed air for cooling the gas turbine engine, and transferring heat to fuel from the compressed air.

Abstract: A portable welder including a housing, a power supply contained within the housing, a welding cable having a proximal end and a distal end, the proximal end of the welding cable being electrically connected to the power supply, a welding electrode that extends from the distal end of the welding cable, and a control system that adjusts welding current delivered to the welding electrode from the power supply based on user input.