Sketch the schematic layout of a gasturbinecombinedcycle GTC

Sketch the schematic layout of a gas-turbine-combined-cycle (GTCC) electricity generating plant. Identify the principal state points on the steam and gas paths, and clearly label the primary plant components. Gas turbine exhaust enters the heat-recovery steam generator (HRSG) of a GTCC plant at 650 C and leaves at 150 C. Liquid water enters the HRSG at 90 C and a pressure of 100 bar, and leaves as superheated steam at 500 C and a pressure of 100 bar. Determine: The mean equivalent temperature (T_ME)) of the gas turbine exhaust during the heat exchange process. The mean equivalent temperature (T_ME) of the water during the heat exchange process. The stream availability of the gas turbine exhaust at entry to the HRSG. The stream availability of the water at exit from the HRSG. The irreversibility of the heat exchange process. The ratio of gas mass flow\' rate, to water mass flow rate. Natural gas (CH_4) is burned in the GTCC at an air:fuel ratio (AFR) of 50:1. Calculate the corresponding relative air:fuel ratio, lambda, of the combustion process. Assuming a lower heating value (LHV) of 50 MJ.kg^-1 for the natural gas, and an air temperature of 800 K at entry to the combustor, estimate the adiabatic flame temperature of the combustion products.

Solution

Parallel flow: AMTD = 105 = (650+150)/2- (5 00+90)/2

Counter flow AMTD = 105, LMTD =98.22

Meq of he turbo exhaust (650+150)/2 =400

of water = 590/2 = 295

Availability: depends on the MTD between the two streams times the heat equivalent

Similarly the absorbing capacity of the water depends one the temp diff and the heat capacity,

for heat transfer these should match.